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UNIDO/IS.330/BeJC^l
25 July 198*1
UNITED NATIONS
INDUSTRIAL DEVELOPMENT ORGANIZATION
ORIGINAL:
ENGLISH
4
J
[ GZUIDELINES
FOR THE ESTABLISHMENT OF SOLAR SALT FACILITIES
FROM SEAWATER, UNDERGROUND BRINES AND SALTED LAKES *
by
M. G. Venkatesh Mannar (1982) * *
H. L. Bradley (Edited and Revised December 1983 ) **
Industrial and Technological Information Bank (TNTIB)
Industrial Information Section
UNIDO Technology Programme
* £ )
t
*
The views expressed in this paper are those of the authors and do not
necessarily reflect the views of the secretariat of UNIDO. This document has
been reproduced without formal editing.
#*
V,84 887^7
UNIDO consultants
FOREWORD
The
Industrial
(INTIB)
came
in
industrial
four
INTIB has
moment,
into
become
20
and T e c h n o l o g i c a l
existence
in
sectors.
Since
a permanent
sectors.
facilitate
the
of
developing
countries.
In
animal
view
consumption
resource
in m o s t
prepared
under
It
assistance
identifying
production
of
and
of
INTIB
is h o p e d
to p l a n n e r s
the
the
most
according
Its
f or
decision
of
this
operation
this
the
is t o
makers
for h u m a n
of this
at
in
and
natural
document
has
been
of UNIDO.
document
promoters
in
suitable
technology
to
local
their
salt
Bank
inception,
main objective
countries,
that
and
successful
availability
programme
pilot
of UNIDO covering,
importance
the
a UNIDO
its
technology
developing
the
as
activity
industrial
choice
1977
Information
will
be
developing
fo r
solar
conditions.
of
countries
salt
in
- 11 -
C O N T E N T S
CHAPTER
I
II
PA3E
IMPORTANCE OF SALT
STATUS OF THE SOLAR SALT
1
11
INDUSTRY IN THE WORLD
HI
THE CHEMISTRY OF SOIAK SALT
30
MANIFACTURE
IV
EVALUATION OF POTENTIAL SOIAR
59
SALT SITES
V
SMALL AND MEDIUM SCALE
80
PRODUCTION OF SALT
VI
MODERNISATION AND MECHANISATION
OF THE SOIAR SALT INDUSTRY
APPENDIX
I
II
BIBLIOGRAPHY
SOURCES OF INFORMATION ON THE
SOIAR SALT INDUSTRY
III
CONFERENCES ON SOIAR SALT AND
ALLIET TOPICS
149
CHAPTER - I
IMPORTANCE OF SALT
The story of salt is the story of mankind.
Salt has played a predominant part in the development of
man's activities, trade, politics and culture from pre­
historic times.
One reason for its overwhelming Influence
is that it is the source for Sodium and Chlorine, two of
the twelve dominant elements in the human body.
These two
elements have important functions in the metabolism of the
body.
Lack of these elements leads to decay and death.
The other reason is that the science of chemistry has used
this Inexpensive and abundantly available commodity as an
important raw material in today's industry.
Directly or
in the form of derivatives, salt finds application in more
than 14,000 ways.
The word salt has become sy m nymous with
Sodium Chloride and will be considered equivalent in this
publication.
Salt for human consumption:
Salt is a principal constituent of extracellular
body fluids i.e. fluids outside the cells as in the tissues,
blood serum and saliva.
Its concentration varies with the
type of fluid being almost the same In blood serum,
cerebral ard spinal fluids, but less In tissue fluids,
sweat and gastric juices.
It becomes part of the human
body even In the embryo stage since the foetus floats In a
saline solution.
The amount of salt Increases during the
period of growth and reaches 230 grams in the body of an
adult.
In the physiological system, salt functions as
sodium Ion and chloride Ion.
Sodium controls muscular
movement Including that of the heart muscles, the perlstalllc
movement of the digestive tract and the transmission of
messages by nerve cells.
The chloride ion ■'roduces hydro­
chloric acid required for digestion.
A principal function
of salt is to regulate pressure and the exchange of fluids
between the lntra cellular fluid and the extracellular
fluid.
For normal health, the salt concentration in the
body can vary only within narrow limits.
of the system has to be replaced.
sweating.
Salt that goes out
Salt is xost mainly through
It Is also passed out through urine but the amount
Is so regulated by the kidneys that the salt remaining In the
system Is maintained at the necessary level.
Salt In the
gastric Juices and the digested food is mostly reabsorbed
in the intestines., except in cases of frequent loose motions
which result in salt depletion.
Salt loss is high in the
tropical summer under conditions of heavy manual work when
excessive sweating takes place.
Such loss of salt through
sweating and other processes has to be made good by intake
of fresh salt with food.
The early man who subsisted on a
meat diet had no need to add salt to his food as meat contains
an adequate amount.
Even today, certain Eskimo tribes living
on seal meat or the Masai tribesmen of Kenya who drink the
blood of cat le, do not need salt.
cereals became his staple food.
When man took to agriculture,
These contain more potassium
salts than sodium salts and hence addition cf salt to the diet
became important.
The rice eating population of the world
requires more salt than others because rice is very deficient
in salt.
In the tropics, where most of the population Is rice
eating, the condition is further aggravated by sweating.
temperate
5 kg/year.
In
climate the annual human requirement of salt is about
In the tropics this is higher.
Chronic inadequacy of salt produces loss of weight,
loss of appetite, inertia, nausea and muscular cramps.
Acute
salt depletion as in gascroenterites, results in dehydration
and reduction of blood volume, interfering with the supply
of oxygen and other elements to the tissues.
When this
happens, the body, in an attempt to maintain the normal
balance in the fluids, releases vital substances from within
the cells, causing damage to health and hazard to lli'e.
Excessive heat, like the summer in deserts, results in salt
depletion and causes heat strokes especially among children.
On the other hand, excess of sodium in salt and
in other foods, can contribute to hypertension, heart, liver
and lddney diseases.
In» such conditions, water (required to
maintain sodium at the proper concentration in blood)
accumulates in the tissues leading to oedema.
Patients are
then advised to be on a low sodium diet.
Salt for animal consumption:
Salt is as important for the health of animals
as for that of human beings.
It is a part of an animal's
body fluid ir. almost the same concentration as in humans.
Experiments Indicate that insufficient salt stunts the growth
of young animals and in the case of fully grown ones produces
lassitude, lowered production of milk, loss of weight and
nervous diseases leading at times to death.
Since fodder
and plant life have little salt, domestic animals have to
be given salt with their feed.
Herbivorous animals in the
wild get their salt from salt licks.
The carnivorous animals
get it from the flesh and blood of the herbivorous ones.
In
today's modern farms, salt is also used as a vehicle for
mineral supplements that are essential for good health of
livestock.
History
and
culture
of
salt:
The primary use of salt for man, ever since he
took to agriculture, is as an essential item of diet both
for him and his cattle.
Salt has also been used from pre­
historic times for flavouring, pickling, preserving, curing
meat and fish, and in tanning.
In view of such widespread
importance, it has become part of our culture and civilisa­
tion.
As one writer points out 'Prom cells in our brains
and bones to customs that spice our languages, salt penetrates
every aspect of our existence'.
'Worth his salt’, ’above
salt’, 'old salt', 'loyal to one's salt', ’the salt of life',
'salary', are expressions and words used every day which
originate from salt.
Salt has been held as a symbol of
divinity, of purity, of welcome and hospitality, of wit and
wisdom in different cultures.
In Sanskrit the word
'lavanya' expressing grace, beauty and charm, is derived
from the word for salt 'lavar.a '.
Salt has been equally Important in trade and
politics.
It was used as currency in many earlier cultures.
Some primitive tribes gave gold, weight for weight, to
purchase salt.
The Hanseatic league developed initially on
the salt trade.
Salt trade was a monopoly of the state in
many countries.
The salt tax, among other things, provoked
the French into revolution.
The same salt tax was a principal
issue in Mahatma Gandhi's civil disobedience movement against
British control of India.
Salt for industrial consumption:
With the advent of industrial civilisation, the
uses and importance of salt have multiplied.
Today only 6%
of the world's annual salt production is directly used for
human consumption, the balance being consumed mainly by chemical
industries.
It is one of the Big Five among the chemicals
which form the base of the chemical industry, the other four
being sulphur, coal, limestone and petroleum.
-7-
The chlor-alkali industry Is the largest
industrial consumer of salt.
Chlor-alkalis consist of
chlorine, caustic soda (sodium hydroxide) and sola ash
(sodium carbonate).
Chlorine is used in the production
of vinyl chloride resins which form the base for a variety
of plastic products, in the paper industry, for water and
sewage treatment, in laundry and textile bleaching, in the
synthesis of numerous organic and Inorganic chemicals
including hydrochloric acid and in the manufacture of insec­
ticides.
Caustic soda and hydrogen gas are the co-products
formed during manufacture of chlorine.
Caustic soda is used
in the manufacture of chemicals, paper t pulp, soaps and
detergents and in vegetable oil refining, rubber reclaiming
and petroleum refining.
It is also used to digest bauxite
in the manufacture of aluminium metal.
Caustic soda is so
Important that its consumption is taken as an index of the
industrial activity of a country.
in the manufacture of ammonia.
Hydrogen is used mainly
Soda ash (sodium carbonate)
is used in glass making, in the manufacture of chemicals,
soaps and detergents.
In recent years the discovery of very
large resources of trona (naturally occurlng soda ash) has
led to a decreased demand of salt manufacture of soda ash.
I
-8-
A small quantity of salt is used in the production
of other chemicals such as metallic sodium, sodium sulphate,
sodium nitrite and nitrate, sodium chlorate, sodium cyanide
and sodium bisulphate.
Salt finds application in food industries such
as canning, baking, processing of flour and other foods,
meat packing, fish curing, dairying and food flavouring.
Salt
is used in animal nutrition as a vehicle for supplementary
minerals which are added in controlled doses.
The leather industry consumes salt for tanning.
Salt is used in de-icing of roads & highways.
Salt is used
as a flux in the production of high purity aluminium alloys,
as a flotation agent in ore enrichment and in soil stabilisers
and pond sealants.
Salt is also used directly in the manufac­
ture of pulp and paper.
Salt, alum and acetic acid are used
to separate emulsified latex in the production of synthetic
rubber.
The petroleum industry uses salt in drilling mud when
underground salt formations are anticipated.
In the textile
and dyeing industry it is used to salt out the dyestuff.
Salt
is used to regenerate cation exchange water softeners for
1
domestic and municipal purposes.
Figure 1.1 Indicates the
various uses of salt.
As the frontiers of the chemical Industry grow,
new applications for salt and Its derivatives are constantly
being discovered.
role In the future.
Salt will be playing an even more Important
-10-
SODIUM
C HLO R ID E
PROCESSED
SOAP MANUFACTURE,
OIL REFINING,
ION EXCHANGE,
HEAT TREATING SALTS.
SOIL STABILIZERS,
FLOTATION «GENTS
R SEWAGE AND
_ _
V
INSECTTEIDE CONCEN- g g ü JJS
•«wahs
S
®
sani : At ION
MAGNESIA t M A G N ESIUM
c h e m ic a l s
(POTASSIUM
FIG .1.1. USES
ME T A L
SALTS
OF SODIUM CHLORIDE
-11-
CHAPTER - II
STATUS OF THE SOLAR SALT INDUSTRY IN THE WORLD
The production of common salt is one of the
most ar.clent and widely distributed industries in tne world.
Salt is produced by mining of solid rock deposits and by the
evaporation of sea water, lake, playa and underground brines.
The latter method accounts for over 50Î of world salt production
today.
The distribution of world salt production in 1980
was as follows:
Name of Continent
Total sait production
(ail types (million
tonnes)
Europe
73-6
North America
56.2
Asia
36.5
South America
6.0
Oceania
5.9
Africa
3.3
181.5
Country-wise production during the years 1978-80
is given in Table 2.1.
Some countries depend entirely on
rock salt, some on solar salt.
There are a few countries
where both forms are produced.
Figure 2.1 gives the location
of solar salt operations in the world.
While the process for
solar evaporation of brines is the same the world over, manu­
facturing techniques and product quality vary considerably.
The demand for salt increases with growth of
population as well as the development of industries.
Apart
from consumption for human use, heavy chemical industries
chiefly chlorine, caustic soda and soda ash require salt as
raw material.
In the developed countries, industrial require­
ments of salt are several times the edible consumption.
In
the USA for Instance, over 95? of the total production of
approximately 41 million tonnes is used for non-edible purposes.
In the developing countries the trend towards Increased
industrial demand for salt has become apparent only during
the past decade.
A brief review of the status of the salt Industry
in the world is presented below:
EUROPE:
Poland, East & West Germany, Czechoslovakia,
Hungary and Holland mine rock salt.
France & Italy have
-AJ-
facilities for both rock and solar salt production.
As
is to be expected in these developed countries, the solar
salt operations are large and are run on a completely mechanised
basis Incorporating scientific techniques of layout design,
brine density and biclogical control.
Countries like the
USSR, Bulgaria and Rumania have a relatively small proportion
of solar salt operations.
Solar salt Is produced in the USSR*
from the waters of the Black Sea and the Sea of Azov.
Greece,
Spain 4 depend almost entirely on solar salt making although
they have rock salt deposits also.
The size of salt works in
these countries ranges from large mechanised works to small
units.
In the hinterland of Spain, there ara salt springs
where salt Is produced on almost a cottage scale by boiling of
brine.
Saline lagoons are also a source of brine in Spain.
Portugal produces rock salt and solar salt in almost equal
amounts.
NORTH
AMERICA:
Canada does not produce any solar salt.
Even in
the USA, only 5% of the production is accounted for by solar
salt.
Indeed, most of the salt obtained by evaporation of
brine from the Great Salt Lake (to recover potassium and
magnesium salts) is flushed back into the lake.
Solar salt
is manufactured mostly along the California Coast by about a
dozen operations and around the Great Salt Lake in Utah,
production in the USA has been almost static during the last
decade oecauss of a reduction in demand
owing to the
closure of several synthetic soda ash plants following the
discovery of natural deposits.
American salt works are note­
worthy for the large number of varieties produced for
different applications.
CENTRAL & SOUTH AMERICA:
In Mexico, solar salt operations play an important
role although there are rock salt deposits.
The 6 million
tonnes per year operation of Exportadora de Sal in the Baja
California desert is considered the largest solar salt
operation in the world today.
There also exist in Mexico
several small and medium sized solar operations managed by
individuals or co-operatives.
Small quantities of solar salt
are produced in the central American countries like Costa
Rica, Nicaragua and Panama bordering the sea.
In south
America, Brazil is the largest producer of salt, the major
portion of which is solar.
Venezuela is building a very
large solar salt works which is expected to become the world's
-15-
second largest salt producer.
In Uruguay, solar salt
production has been attempted but abandoned.
solar salt Industry.
Chile has no
In Argentina and Peru, all the solar
salt is produced from brine wells.
In Cuba, salt is produced
elmost entirely by solar evaporation of sea water.
In this
country there is potential for increasing production because
of favourable climatic conditions and availability of land.
Bahamas & Netherlands Antilles have lately emerged as large
scale producers of solar salt from sea water.
However, in
recent years the Bahamian operations have suffered production
set backs due to heavy rainfall.
ASIA:
In Asia, the Kiddle Eastern countries like Syria,
Iraq and Iran depend mostly upon rock & playa salt.
Turkey
is an exception and concentrates on solar salt making.
Production methods are traditional.
However, a few modern
solar salt operations are now being developed in Turkey,
Iraq and Iran.
Israel produces a small quantity of solar
salt from the Dead Sea.
In the Indian subcontinent, Pakistan
has extensive deposits of rock salt but also produces some
solar salt.
In India, almost all the salt is produced by
Tc
solar evaporation cf sea water, underground springs and
inland lake brines.
Here salt works range from
to large sized operations.
very
Salt works are operated
small
by
private and government owned companies, co-operatives and
individuals.
Solar salt is the only form of salt produced
in Sri Lanka, Bangladesh and Thailand where the
salt works is mostly small.
size of
In Indonesia, the government has a
monopoly on salt production and the state owned salt company
produces salt in half a dozen locations.
The production
methods adopted in Kampuchea and other south east Asian
countries where small holdings predominate, are primitive
and the salt is not very pure.
Salt making has had a very
important role in China from ancient times.
In spite of rock
salt resources, about 75i of the production is solar salt from
sea water.
of China.
Salt farms are worked in every coastal province
In the Philipines and Taiwan salt is produced
entirely by solar evaporation of sea water in small and medium
sized operations.
In Japan, the pressure on availability of
land has encouraged the development of sophisticated ion
exchange technique for recovery of salt directly from sea
water,
Direct evaporation methods using a combination of
solar and artificial evaporation are also employed.
However,
the production by these methods is small and Japan today
is the world's largest importer cf salt.
OCCEANIA:
Australia has enormous reserves of rock salt
as well as facilities for solar salt manufacture.
The main
locations where solar salt is manufactured are the South
Australian and West Australian coasts.
Five companies
opaiu..xng along the West Australian coast together produce
nearly 8 million tonnes in highly mechanised operations.
of this production is exported to Japan.
Most
In terms of design
and layout the Australian salt works can be considered to he
the most modern, producing an exceedingly pure product.
their profitability
However,
has been low owing to low price realisation.
New Zealand produces a small quantity of solar salt to meet
domestic requirements despite unfavourable weather conditions.
Recently rock salt deposits have been discovered in the
Antartic region.
AFRICA:
In contrast vO Australia, the techniques in the
African countries are conventional and in some areas, ancient.
Solar salt is produced only in certain countries while others
depend on rock salt and other salt sources.
In the former
category are Egypt, Libya and Ethiopia.
In Egypt, there
exist small and medium sized salt pans.
In Libya and
Ethiopia there are several small operations.
Ethiopia
produces salt along the Red Sea coast and exports it.
There
is very good potential for improvement of production in this
country if modern techniques are adopted and transport and
port facilities are improved.
In general the Red Sea area
is well suited for solar salt production from the point of
view of salinity, climate and topography and deserves detailed
investigation.
Mozambique is a country with a long coastline
but very little salt is produced as climatic conditions are
not favourable.
In Tanzania conditions of humidity and rainfall
are not conducive for solar salt manufacture.
Nevertheless,, a
small quantity of salt is manufactured from sea water and the
major portion by solar evaporation of playa and lake brines
In Somalia small quantities of solar salt are being produced
for local consumption.Mauritius
are used for solar salt production.
small shallow paved ponds
Niger produces playa
salt by solar evaporation almost as a cottage industry.
forms the mainstay of its economy.
in brine marshes are out
This
In Zambia plants growing
and squeezed in water to get a weak
brine solution which is heated in pots to recover sa]t.
In
Mauritania salt is made by solar evaporation of brine from
inland lakes.
Although South Africa has a long coastline
and has a solar evaporation plant, the major portion is from
solar evaporation of playa salt brine after the rains.
In
Namibia there is natural solar evaporation of sea water which
gets trapped in tidal basins.
In most of West Africa condi­
tions for solar salt production are unsatisfactory because of
the humid climate and low salt concentration of sea water
owing to dilution by large rivers.
However, in countries such
as Ghana, Guinea, Senegal and Togo solar salt production is
feasible.
The North African countries have by far the most
favourable conditions in Africa for solar salt manufacture.
These include Algeria, Morrocco, Tuijfia and Egypt.
In Algeria
most of the salt is produced from salt lakes although there is
g>od potential for sea salt production also.
There is tremendous potential for increasing
output and improving the quality of the salt produced in the
African, Asian and South American countries.
In several
countries, simple machines for the harvesting and handling of
salt could be introduced.
Improved techniques can be adopted
for designing the concentrating and crystallising ponds and
quality control procedures introduced for production of high
purity salt.
The recovery of chemicals like Bromine, Magnesium
-20-
and Potassium salts from bittern could be the next step.
A major portion of the world output of salt
(more than 80Z) is consumed in the country in which it is
produced.
Since bulk salt for industrial use has a relatively
low value, transportation costs usually form a large part of
the delivered cost.
trade.
This is a disadvantage in international
Japan is a major industrial country that depends
largely on salt imports of nearly 10 million tonnes per year
from Australia, Mexico and mainland China to meet the require­
ments of its chemical industyy.
Other salt importing countries
are Australia, Bahamas, Canada, Mainland China, Mexico,
Netherlands and Spain.
There is however, fairly widespread
international trade in refined grades of salt for table use.
The U.S.Department of Mines had made the following
forecasts for growth in world demand for salt:
Production in 1980
165 million tonnes
2000 Forecast range
Low
High
282.8 million tonnes
452.1 million tonnes
Probable Demand
1990
2000
253-6 million tonnes
364.5 million tonnes
3-7 %
-21-
In the developing countries the demand growth
rate is expected to be faster (k.2t) than in countries like
the USA (2.OX).
This is because many countries in various
stages of economic development are expanding industries
that consume salt as raw material.
Most countries produce
salt only at 70 - 80? of the full rated capacity since the
production of salt by solar evaporation is subject to weather
fluctuations.
To meet anticipated increases in demand, salt
producers in many countries will have to increase productivity
of existing operations, increase the capacity of existing
plants or construct new facilities.
Today production economics
and quality considerations indicate that the size of solar
salt operations has to be progressively increased from a
cottage level of 500 tonnes/year to atleast a small scale
level of 2000 to 3000 tonnes/year.
The fact that solar salt
production utilises the abundant and inexhaustable resources
of the sun and the sea should encourage such a growth.
-22-
TABLE - 2.1
COUNTRYWISE
PRODUCTION
OF
SALT*
(Thousand metric tons)
Country
2
1978
1979p
el636
441
6465
6895
46
19S06
North America:
Bahamas
Canada
Costa Rica
Dominican Republic
35
38
El Salvador6
Guatemala
3685
3 7044
40
38
38
27
27
27
11
310
e 32
15
632
6 32
50
50
50
5647
e5636
600C
Antilles6
400
400
400
Nicaragua
el 8
6 18
20
15
19
19
13352
13537
10734
25619
25
28092
25
25949
25
1
701
1
663
3 31
^627
Honduras
Leeward and
a
Windward Islands'"
Mexico
Netherlands
Panama
United States including
Puerto Rico:
Rock salt
Other salt:
United States
Puerto P.icoe
South America:
Argentina:
Rock salt
Other salt
•
Source: US Bureau of Mines Minerals Year Book (short tonnes
have been converted into metric tonnes
(thousand metric tonnes)
2
1978
1979p
1980*
2733
2806
3000
395
591
500
178
575
176
459
173
445
493
158
*51
e155
500
3244
50
6*
68
1
322
156
1
381
208
3
J411
200
87
86
3122
Czechoslovakia
258
272
Denmark
325
381
273
382
H59
574
3301
1105
1191
31115
865
3867
1805
4504
31277
34424
2694
53
3004
55
3091
56
Country
Brazil
Chile
Colombia:
Rock salt
Other salt
Peru
Venezuela
Europe :
Albanlae
Austria:
Pock salt
Evaporated salt
Salt In brine
Bulgaria
Prance:
Rock salt
Brine salt
Marine salt
Salt in solution
German Democratic
Republic:
Rock salt
Marine salt
-24(thousand metric tonnes)
Country
2
1978
1979p
1980e
Germany, Federal
Republic of:
Marketable :
Rock salt
Marine salt &
other salt
6860
8978
7909
5824
6143
6091
134
155
3 (4)
Iceland
®(4 )
155
®(4 )
Italy:
Rock salt 4
brine salt
3729
4499
1181
Malta
1213
1
el
1273
1
Netherlands
2945
3959
J3471
Rock salt
1438
1461
1091
Other salt
2964
2977
2273
327
149
408
409
e150
127
1661
3083
1654
1655
3076
3073
Rock salt
1418
1420
1455
Marine salt & other
evaporated salt5
1280
1263
1355
392
392
3369
14527
rl4327
14527
Greece
Marine salt
1
4005
Poland:
Portugal:
Rock salt
, .-ine salt
Romania:
Rock salt
Other salt
Spain:
Switzerland
U.3.S.R.e
-25(thousand metric tonnes)
Country
2
1978
1979F
1980
131*
176*
*2*6
1593
1600
2000
3000
United Kingdom:
Rock salt
Brine salt
6
Other salt^
3919
*32*
Yugoslavia:
Rock salt
85
21
137
193
193
—
172
165
173
50
50
50
e (*)
756
e (*)
617
(*)
700
10
r15
r15
e50
93
50
91
50
620
e12
10
20
12
630
30
Mauritania6
5
1
5
1
5
1
Marutius
6
6
35
28
6
102
28
227
227
1
Karine salt
Salt from brine
21
3378
Africa:
Algeria
Angolae
Benin
Egypt
Ethiopia^:
Rock salt
Marine salt
Ghana
50
Kenya:
Crude
20
612
Refined
Libya
15
30
Madagascar
Mali6
Morocco
Mozambique
e
Namibia (marine salt )6
Niger6
Senegal
1*0
' r3
61*0
Sierra Leone6
182
182
10
1§5
28
227
3
1*0
182
-26-
( thcu$3nd n s t n c
Country^
1978
t onnss)
1979P
19806
re27
30
330
491
540
3568
Sudan
72
82
Tanzania
20
37
1
82
36
1
^437
Somalia
South Africa
Republic of:
Tunisia
426
61
440
Uganda6
1
1
1
Afghanistan
81
20
Bangaladesh
787
Burma
305
675
258
5
700
19571
14801
341
367
317316
3724
6
37
5
6710
5
7046
35
235
r700
708
7273
656
r700
600
82
r100
122
107
91
110
1075
30
1093
1091
25
30
12
r26
30
545
545
19
19
573
20
Togo
326?
China:
Mainland
Taiwan
Cyprus
--
India:
Rock salt
Marine salt
Indonesia
_
e s
Iran
Iraqe
Israel
q
Japan^
Jordan
Kampuchea6
Korea, North6
Kuwait
-27-
(thousand metric tonnes)
Country
2
1978
1979p
1980*
18
20
Lebanon*
15
12
r10
12
Mongolia*
15
15
15
414
513
500
227
193
2CÔ
Philippines
226
354
Sri Lanka
150
339
122
127
r*109
75
62
Laose
Pakistan:
Rock salt
7
Other salt
Syria
Thailand:
Rock salt
Other salt*
Turkey
Vietnam*
12
164
11
164
12
164
951
1133
1091
‘532
518
Yemen Arab Republic
27
r527
64
Yemen, People’s
Democratic Republic of*
75
75
80
5778
5812
35326
65
70
73
r 167279
172214
165098
65
Oceania:
Australia (marine salt
and brine salt)
New Zealand
TOTAL
-26-
eEstinated
Preliminary
rRevised
Pable includes data available through June 17, 1961
2
Salt is produced in many ether countries, but quantities
are relatively insignificant and reliable production
data are not available
^Reported figure
Less than 1/2 unit
^Includes production the Canary Islands (Spain’s provinces
of Las Palmes and Santa Cruz de Tenerife) totalling
17,434 short tons in 1977, 15,766 ~shcrt tons In 1976,
6,665 short tons in 1579 (1976 and i960 not available)
Data captioned 'Brine salt' for the United Kingdom are tne
quantities of salt obtained from the evaporation of brines
that captioned 'Other salt' are the salt content of brines
used for purposes other than production of salt by evapora
tion.
7
Year ending June 30 of that stated
8
9
Year beginning March 31 of that stated
Includes Ryukhy Islands
•
LOCATIO N OF SOLAR SALT
IN THE W O R LD .
O PER A TIO N S
CHAPTER -
THE
Salt
from t h e
CHEMISTRY OF
III
SOLAR
SALT
MANUFACTURE
sea:
The oceans are the m o s t prolific
chloride accounting
The
reserves
tonnes.
source
in
^art
seawater.
in
from
of
SOdiun
%orld
Chloride,
Magnesiun
and
Of these th e more
Table
Bromine.
3.1
iiqportant
of Magnesiun
from
lists 60 elements
is
found
the amounts present.
injportant o n e s a r e :
CONCENTRATIONS
PER MILLION)
Chlorine
19000
Sodiun
10500
Sulphur
885
Chlciun
400
Potassiun
380
Bromi ne
65
These elements exist
Magnesiun,
(PARTS
1360
Magnesiun
Sodiun,
65%
vor 1 d a r e
their concentration and
ELEMENT
ions -
50 m i l l i o n b i l l i o n
element including gold and uraniun
in seawater.
seawater giving
sodiun
production today.
the seas are an
Bromine produced in th e
Almost every
in t r a c e s
of
the seas are estimated at
for Potassium,
Metal and 68%
found
for over 50%
source of
in t h e
Potassiun,
i o n i c states.
Chlorine and
Five
Sulphate -
CONCENTRATION AND AMOUNTS OF THE ELEMENTS IN SEA WATER
ELEMENT
Chlorine
Sodium
Magnesium
Sulphur
Calcium
Potassium
Bromine
Carbon
Strontium
Boron
Silicon
Fluorine
Argon
Nitrogen
Lithium
Rubidium
Phosphorous
Iodine
Barium
Indium
Zinc
Iron
Aluminium
Molybdenum
Selenium
Tin
Copper
Arsenic
Uranium
Nickel
Vanadium
Joncentration
mg/litre
19, 000.0
10, 500.0
1 , 360.0
885.0
400.0
380.0
65.0
28.0
8.0
4.6
3.0
1.3
C.6
0.5
0.17
0.12
0.07
Amount of
element in
seawater
(tonnes/
cubic mile)
10Î
89.5
49.5
6.4
4.2
1.9
1.8
306,000
132,000
38,000
23,000
10g
io5
lo£
lo2
10b
2.1
X
X
1.4
X
0.6
0.6
X
0.1
0.04
12,000
X
X
X
X
X
6 , 100
2,000
X
2,800
2,400
800
570
330
930
X
780
260
X
280
140
94
47
47
47
47
19
14
14
14
14
9
9
0.002
0.002
X
14,000
0.06
0.004
0.003
0.003
0.003
0.003
29.3
16.3
7,100
4,700
0.03
0.02
0.01
0.01
0.01
0.01
Total
amount
in the
oceans
(tonnes)
X
X
190
X
110
93
X
X
47
31
X
16
X
16
16
X
16
6
5
5
5
5
3
3
X
X
X
X
X
X
X
X
X
X
1015
1°15
1015
l°ll
10 9
10 9
10 9
10 9
10 9
10 9
1° I
1° I
1° \
109
109
109
109
109
109
109
109
1°9
109
109
109
1°9
109
НГ
I
ч
Silver
Lanthanum
Krypton
Neon
Cadmium
Tungsten
Xenon
Germanium
Chromium
Thorium
Scandium
Lead
Mercury
Gallium
Bismuth
Niobium
Thallium
Helium
Gold
Protactinium
Radium
Radon
.002
0.001
0.0005
0.0005
0.0005
0.000*4
0.0003
0.0003
0.0003
0.0003
0.0001
0.0001
0.0001
0.0001
0.00007
0.00005
0.00005
0.0000*)
0.000C3
0.00003
0.00003
0.00002
0.00001
0.00001
0.000005
0 .00000*1
2 * 10ll0
1 x 10 10_15
0.6 x 10 3
9
5
2
2
2
2
1
1
1
1
0.5
0.5
0.5
0.5
0.3
0.2
0.2
0.2
0.1
0.1
0.1
0.1
0.05
0.05
0.03
0.02
c
1 x 10“2
5 x 10"'
3 x 10"^
3 X
1.5 X
0.8 X
0.8 X
0.8 ’ x
0.6 X
5 X
5 X
5 X
5 X
150 X
150 X
150 X
150 X
110 X
78 X
78 X
62 X
*16 X
D6 X
D6 X
31 X
15 X
15 X
8 X
6 X
3000
150
1 X
c^cr\a\o>cr\o\cr\cr\a\cr\CT\cr\cno\c7\(TiCD ooaj co'~o vo vo' û 'ûvû
Manganese
Titanium
Antimony
Cobalt
Caesium
Cerium
Yttrium
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
-33-
daninate to
such
an extent that
considered
as
solutes
salts.
as
seawater
a q u i n a r y system.
is
sometimes
It i s c o n v e n i e n t
The major ch«nicals
to study the
found in o n e litre of
seawater are
Percentage of
t o t a l wt. o f
dissolved salts
Cbncentration
( g m / l i tre)
Dissolved salts
(in o r d e r o f
p r e c i p i t a t i o n)
Calciun Carbonate
(CaCo3 )
0.12
0.34
Calciun Sulphate
(CaSo4 )
1.26
3.61
27.21
77.74
1.66
4.74
0.86
2.46
3.81
10.88
0.08
0.23
Sodiun Chloride
(NaCl)
Magnesiun
(MgSo4 )
Sulphate
Potassiun
(KC1)
Chloride
Magnesiun
Chloride
(MgCl2 )
Magnesiun
(M g B r 2 )
Bromide
Sodiun
constituting 80%
seawater.
salts
One
giving
it
variable within
Chloride also
by
weight
litre of
of the
c a l l e d Halite,
total salts dissolved
seawater contains
a specific g ravity of
a
small
range.
dominates,
in
3 5 gins o f d i s s o l v e d
1.034.
* This
value
is
The
salinity of
factors i n c l u d i n g location,
river discharges.
in t h e
mid sea.
stratified
in the
vary,
and,
upon a number of
tenperature and dilution by
is l o w e r a t s e a s h o r e s a n d e s t u a r i e s t h a n
features like t h e partly
layers in bays with constricted outlets as
Australian coast result in h i ^ i e r salinity.
fact about
the relative
consistently
season,
Geographical
surface
south
remarkable
It
seawater depends
the
s e a w a t e r is t h a t t h o u g h
proportion of the
same
through all
salinity may
dissolved elements is
e v e r y w h e r e in t h e world,
geologists believe,
A
in all seasons
times.
FOr the manufacture of salt and its byproducts by
the solar evaporation of seawater, a knowledge of both the
canposition of seawater and its phase chemistry is necessary.
Considerable research has been done in this connection by the
Italian scientist, Usiglio.
His experiments on the separation
of salts by the evaporation of sea brine have been performed at
2 5*C which is normal for a temperate climate.
The ruling
tenperatures over salt pans in the tropics are generally
between 30*C and 35*C.
Some work has been done at these higher
tenperatures by forschart (1940).
The cone lus ions are broadly
the same because the pattern of phase relationship remains the
same.
The actual values depend upon local conditions and
results will not be absolutely identical at any two locations.
-3 5 -
In
tion
is
studying the phase chemistry,
given on the
* Be
( D e g r e e Baune)
*
Table
density
for
(gms/ml) .
solutions
Baume
145 -
3.2
brine concentra­
scale w h i c h is d e f i n e d as
145
--------------------------------------------------specific gravity of the b r i n e a t 15.6*C
gives t h e c o n v e r s i o n figures
Table
from 'Be to
3.3 g i v e s t h e t e m p e r a t u r e c o r r e c t i o n s
w h ose d e n s i t y is measured a t different
temperatures.
The order of
separation of
the dissolved salts
d e p e n d s o n t h e i r r e l a t i v e s o l v b i l i t y wfriich i s
Calcium
Carbonate being
The highly
the least soluble,
soluble magnesium
Salt
CaC03
C a S 0 4 .2H20
salts are
given bela*.
separates out
separated
last.
S o l u b i l i t y a t 30* C
1 0 0 g m o f water)
—
0.2
NaCx
3 6 .3
KC1
37.0
MgSo4 .7H20
40.8
Mg Cl 2
56..0
MgBr2
104.0
first.
(gm in
I
-3 6 -
TABLE - 3.2
RELATION BETWEEN BRINE DENSITY IN GMS/KL
AND DEGREES BAUME
Density
oBe
gm/litre
1.020
1.021
1.022
1.023
1 .021*
1.025
1.026
1.027
1.026
1.029
1.030
1.031
1.032
1.033
1.C31*
1.035
1.036
1.037
1.038
1.039
1.0H0
1.01*1
1.01*2
1 .01*3
1.04U
1.01*5
1.0H6
1.01*7
1.01*8
1.01*9
1.050
1.051
1.052
1.053
1.05H
1.055
1.056
1.057
1.058
1.059
1.060
l
Density
o3e
gm/litre
2.8
3.0
3-1
3.3
3.K
3.6
3.7
3-8
i*.0
i*.l
1*. 2
1*.1*
1*. 5
1*.7
i*.8
K.9
5.0
5.1
5.3
5.H
5.5
5.7
5.8
6.0
6.1
6.2
6.1*
6.5
6.7
6.8
6.9
7.0
7.2
7.3
7.5
7.6
7.7
7.9
8.0
8.1
8.2
1.061
1.062
1.063
1.061*
1.065
1.066
1.067
1.068
1.069
1.070
1.071
1.072
1.073
1.071*
1.075
1.076
1.077
1.078
1.079
1.080
1.081
1.082
1.C83
1.081*
1.085
1.086
1.087
1.088
1.089
1.090
1.091
1.092
1.093
1.091*
1.095'
1.096
1.097
1.098
1.099
1.100
1.101
8.
8.5
8.7
8.6
8.9
9.0
9-2
9-3
9.1*
9-5
9.6
9-7
9-9
10.0
10.1
10.2
10.3
10.5
10.6
10.7
10.8
11.0
11.1
11.2
11.3
11.5
11.6
11.7
11.8
11.9
12.0
12.1
12.3
12. **
12.5
12.6
12.7
12.8
13.0
13.1
13.2
-3 7 -
TABLE - 3-2 (CONTD)
RELATION BETWEEN BRINE DENSITY IN OMS/KL
AND DEGREES BAUME
Density
gm/litre
1.102
1.103
1.104
1.105
1.106
1.107
1.108
1.109
1.110
1.111
1.112
1.113
1.114
1.115
1.116
1.117
1.118
1.119
1.120
1.121
1.122
1.123
1.124
1.125
1.126
1.127
1.128
1.12S
1.130
1.131
1.132
1.133
1.134
1.135
1.136
1.137
1.138
1.139
1.140
°Be
13-4
13-5
13- 6
13. 7
13.8
14.0
14.2
14.3
1*. 4
14.5
14.6
14.7
14.9
15-0
15-1
15-2
15.3
15-4
15-5
15.6
15-7
15.8
15.9
16.0
16. 2
16.3
16.4
16.5
16.6
16.7
16.8
16.9
17.0
17.1
17.3
17.4
17.5
17.6
17.7
Density
gm/litre
1.141
1.142
1.143
1.144
1.145
1.146
1.147
1.148
1.149
1.150
1.151
1.152
1.153
1.154
: .155
1.156
1.157
1.158
1.159
1.160
1.161
1.162
1.163
1.164
1.165
1.166
1.167
1.166
1.169
1.170
1.171
1.172
1.173
1.174
1.175
1.176:
1.177
1.178
°Be
17. 8
17. 9
18. 0
18. 1
18. 2
18 .3
18. 5
18. 6
18. 7
18.8
is. 0
19- 1
19. 2
19. 3
is. K
19- 5
is. 6
19. 7
19. 8
19- 9
20. 0
20. 2
20. 3
20. 4
20. 5
20. 6
20. 7
20. 8
20. 9
21. 0
21. 1
21. 2
21. 3
21.
21. 5
21. 6
21. 7
21. 8
TABLE - 3.3
DENSITY OF CONCENTRATED SEA WATER - CORRECTION FOR
TEMPERATURE
TOTAL CORRECTION TO 20°C. DENSITY IN GM/ML
Density range, gm/ml at 20°C
Temp
n
C
21
22 •
23
2*1
25
26
Subtract
correction
from
measured
density
1.05 1.10
.002
.002
.001
.001
.001
.001
.001
.001
—
—
1.10 1.15
1.15 1.20
1.20 1.25
1.25
i.3o
.002
.002
.002
.002
.001
.001
.001
.001
.001
—
.003
.003
.002
.002
.002
.002
.001
.001
.001
.001
.003
.003
.003
.003
.002
.002
.002
.001
.001
.001
.003
.003
.003
.002
.002
.002
.002
.001
.001
—
.003
.003
.002
.002
.002
.002
.001
.001
.001
--
.001
.001
.002
.002
.002
.001
.001
.001
.002
.003
.003
.001
.001
.002
.002
.003
.003
.001
.001
.002
.002
.003
.003
.001
.001
.002
.002
.003
_ _
Add
correction
to measured
density
.001
.001
.001
.002
.002
38-
10
11
12
13
Vi
15
16
17
18
19
20
1.00 1.05
TABLE - 3.3 (CONTD)
DENSITY OF CONCENTRATED SEA WATER - CORRECTION FOR
TEMPERATURE
TOTAL CORRECTION TO 20°C DENSITY IN GM/ML
Density range, gm/ml at 20°C1*
Temp
°C
1.05 1.10
.003
.003
.00*4
.00M
.00*1
.005
.005
.006
.006
.003
.003
. 00*4
.00'4
.005
.006
.007
.007
.007
1.10 1.15
1.15
1.20
1.20 1.25
.00^
.oou
.005
.005
.006
.006
.007
.007
.008
.OO4»
.005
.005
.006
.006
.007
.007
.008
.008
.00*4
.005
.005
.006
.006
.007
.007
.008
.008
1.25
1.30
.00*4
.00*4
.005
.006
.006
.007
.007
.008
.008
39-
27
28
29
30
31
32
33
3“
35
1.00 1.05
-4 0 -
The concentrations at which the m o r e c o m m o n o f
salts
the
p r e c i p i t a t e are:
O r i g i n a l sea water
remaining
(percentage of
weight)
100.00
Salt b e g i n n i n g
to precipitate
Conposition of
salt
Calcite
CaCo3
32.22
Gypsun
c a s o 4 .2 H 2o
12.13
Halite
NaCl
2.45
Astrakainite
N a S o 4 .Mg S o 4 .4 H 20
2. 18
lesomi te
MgSo4 .7H20
1.96
Kainite
MgSo4 .KC1.3H20
1.63
Hexahy? rite
Mg S o 4 .6 H 20
1.22
Kieserite
MgSo4 .H20
1.18
C&rnallite
KCl.MgCl2
0.93
Bi s c h o f i t e
MgCl2 .6H20
Table
various salts
at different concentrations.
sents graphically
of sea
water.
is p l o t t e d
3.4 giv e s t h e a m o u n t s of
the deposition of
. 6 H 20
precipitation of the
Figure
salts during
3.1 r e p r e ­
concentration
Here t h e extent o f d e p o s i t i o n o f d i f f e r e n t s a l t s
against the brine concentration expressed
in
*Be.
-4 1 TABLE - 3-4
SEPARATION OF SALTS ON PROGRESSIVE EVAPORATION
OF SEA WATER
°Be ct
21°C
Volume
on evapo­
ration In
litres
3-5
7.1
11.5
in .00
16.75
20.60
22.00
25-00
26.25
27.00
28.25
30.10
32.П0
35.00
1.000
0.5330
0.3160
0.2П50
0.3900
0 .1ПП5
Iron
Oxide
Calcium
Gypsum
Carbonate CaSo^
Fe2°3
CaC0„
3
e
#9
„
0.003
0 .06П2
Traces
Traces
0.0530
0.1310
0.1120
3.261П
О.ООП9
0.0130
0.0262
• •
• *
• *
0.5600
0.5620
0 .18П0
0 .06П 0
0 . 0990
0.1П76
0,0700
9.6500
7.8960
0.0302
o.oinn
2.62П0
0.017П
0.0230
0.0162
• .
2.2720
•*
l.nono
0.025П
0.5382
1.7П 88
27.107П
0 .62П2
2.5885
1.85*5
29.6959
2 .4787
Total separated
0.0030 0.1172
Remainder in
solution i.e.,
0.0162 litres
Total content
in one litre
Magnesium
sulphate
m9
0.1600
0.0508
0.0950
Common
Salt
0.0030 0.1172
1 .7П88
42TABLE - 3.** (COKTD)
SEPARATI OK OF SALTS OK PROGRESSIVE EVAPORATION
OF SEA WATER
°Be at
21°C
Magnesium
Chloride
Mgci2
Sodium
Bromide
NaB2
Potassium
Chloride
KCL
3.5
7.1
0.0672
Traces
11.5
1*1.00
Traces
0.6130
0.5620
0.18*10
0.1600
3.32*10
16.75
20.60
22.00
25.00
0.0078
26.25
27. Q0
0.0356
28.25
30.10
0.0*13**
0.0156
32.*10
35.00
Total
separated
Remainder
In soln.
1 .e.
0.0162
litres
Total
content in
one litre
Total
sepa­
rated
Cumulative Total
Sepa­
rated
In
solution
0.000
0.0672
38.HH72
38.3800
38.3800
38.3800
37.7670
37.0060
37.0210
36.9610
33.5370
0.0672
0.0672
0.6802
1.2*122
1.*1262
1.5862
*1.9102
0.0728
9.8*162
8.108H
1*. 756*1
22.86*18
0.0358
2.7066
0.02*10
0.0518
2.3722
25.571H
27.9** **6
10.5026
0.027*1
0.0620
2.0316
29-9762
8.*i709
0.1532
0.22 2*»
29-9762
3.16*10
0.3300
0.5339
8.11709
3-3172
0.852*1
0.5339
38,-111171
23.6903
15.762*1
12.8756
i
A»
u
i
F IG . 3 .1 . DEPOSITION
OF
SALTS O U R IN G
C O N C E N TR A TIO N
OF S E A
WATER.
-4 4 -
As indicated by this graph, the evaporation process
is conveniently divided into four distinct phases.
The first
phe.se is from 3* Be to 13* Be when most of the carbonates
precipitate as salts of iron, magnesium and calcium.
Miile
iron carbonate and magnesian carbonate crystallise completely
by 13* Be, calcium carbonate crystallises up to 90S, the
ronaining 10S precipitating by 15* Be in the next phase.
These
carbonates have little practical value.
The second phase, extending from 13* Be to 25-4*
Be, centres round gypsum.
This crystallises as needle shaped
crystals of CaSo4 .2H20 from 13* Be to 16.4* Be and there­
after as anhydrite CaSo4 . 85% of the calciun sulphate
present is precipitated in this phase.
The precipitation of
the remaining 15% is spread over the third and fourth phases in
decreasing amooits, right uitil evaporation is complete.
Gypsun is used in the production of cement and plaster of
paris.
It is also of immediate value in a solar salt works
since its crystals are used to pave the pond floors thus
preventing leakage of brine into the soil.
The third phase extends between 25.6* Be and 30*
Be.
Common salt (NaCl) precipitates out in this phase.
Crys­
tallisation starts at 25.6* Be and its rate rapidly increases
in the initial stages.
72% of the total amount is precipitated
by 29* Be and 79% by 30* Be.
At higher levels of salinity the
J
-45-
crystallisation slows down considerably and is complete only
with the completion of evaporation.
The concentration at vhich
sodium chloride starts to crystalline is known as the salting
point and the mother liquor at this point is called the pickle.
At the end of the phase, when the concentration is 30* Be, the
liquor is called bittern because of its characteristic bitter
taste.
Sodiun chloride is formed as cubic crystals.
colorless, odourless and has a characteristic taste.
It is
It has a
specific gravity of 2.165 and a molecular weight of 58.45.
Its
solubility in water varies only slit^itly with tenperature.
Though salt is the predominant precipitate in the
third phase it is not pure because gypsum is also precipitated,
especially in the earlier stages.
At the higher concentrations
near 30* Be, some bromides, potassium chloride and magnesian
sulphate from the fourth phase appear.
The technique of salt
manufacture involves fractional crystallisation of the salts to
obtain sodiun chloride in the purest form possible.
According to typical standards adopted in
developing countries, the purity required is 99.5% for grade I
industrial salt, 98.5% for grade II industrial salt, 96.0% for
edible common salt, 99.6% for dairy salt, and 97.0% for table
-4 6 -
salt.
In advanced countries the specifications are more
stringent, the minimum purity prescribed for table salt being
99.5* .
Figure 3.2 shows the considerable shrinkage in the
volume of brine that takes place during salt nanufacture.
The
volume is 19% of the original at the beginning of phase I when
gypsum starts crystallising, 9% at the salting point when salt
crystallises and 3% when phase III ends and bittern is formed.
The relation of vapor pressure of brine vs vapor
pressur® of fresh water is dependent upon fresh water tempera­
ture and Mg++ concentration.
The relative rate of brine
evaporation is dependent upon this vapour pressure of brine vs
vapour pressure of water and the percent relative hunidity.
Figure 3.3 is nomogram for calculating evaporation rate ratio
between brine and evaporation of fresh water in evaporation pan
given fresh water tenperature, Be of brine and ambient hjgrometry.
This phenomenon is discussed in detail in Chapter IV.
Figure 3.4 plots relationship of Mg++ with Be of normal sea
water brine.
Figure 3.5 shows the results of measurements in
reduction of evaporation rate with increase in brine density at
different locations.
If the rate is taken as* 1 at salting
point, it drops dawn to 0.6 or lower at the end of phase III.
The evaporation of bittern to produce typroducts is known to
salt makers to he a tediously slow process.
I
▲
1
A
-4 7 -
F IG .3 .2 .
R E D U C T IO N IN THE VOLUME
IN C R E A S E IN D E N 5ITY.
OF
BRINE
W ITH
FRESH WATER TEMPERATURE ,*C
Ч|
5*
I
8
5
I
I
I
I
»
8
«
$
i
-*______ J
I
I
I
I
I
I
m 5
Ж
¡s
я
i«
Я
S 3
п
за
-Í о
о»
8
я
о
m
с*
я <
я
?
гл
$
la
la
ì
jp
ж
Ж
(/>
*
8
i
.1
8
..., i
j-
— »----------L _ l
g /!*«♦♦
Be
FIG М
ВШ Г lég *♦ V5. BAUME
(SOW CE H L BRADLEY, 1983 )
TOTAL
EVAPORATION
(mm/VEAR)
-50-
F IG .3 5 .
EFFECT OF D ENSITY UPON EVAPORATION
R ATE.
-5 1 -
F i g u r e 3.6
deposited
demonstrates the percent of
in crystallisers
crystalliser
in
brine.
will b e used
This
For
be
determined
F i g u r e 3.7.
vs
Be d r a i n e d a s b i t t e r n f r o m t h e
relation to the original
in
Chapter
See
Figure
3.8
A nixnber o f
magnesium and
either
or as double crystals
metastable conditions.
weather conditions.
salt
Normally
complex.
tonnes
an adequate
o r in
by
potassiun
These conditions are
market nearby and the
year.
A brief account of
sodium chloride and
out
r e c o v e r y o f typro ducts o f potassium,
of salt per
precipitating
evapora­
sulphates of
in equilibriun
scale,
the chemistry
salts,
solar
producing more than
The r e c o v e r y p r o cesses are
If t h e b i t t e r n i s c o n c e n t r a t e d
out
s e a water brine.
bitterns are n o t utilised
operations must b e on a large
100,000
b y u s e of
potassiun chloride separate
and b r o m i n e becomes economical.
that there should be
pond
The p h a s e c h e m i s t r y i s a l s o a f f e c t e d
under certain conditions,
magnesiun
given
IV relating t o the
potassium and
singly
approximation can
for conposition o f
the b i t t e r n is conplex.
salt in
IV.
Be o f b r i n e a t a n y
The c h e mistry of p h a s e
tion of
content of
a given saline area a rough
of the
salt
is now given:
by
evaporation with­
a mixture of
magnesium sulphate separates
the remanent
out.
this
OF ORIGINAL VOLUME
FIG 3 6
BRINE RECOVERY FROM CRYSTALLISERS
----2г9
T
30
T
si
!
32
BAUME
(SOURCE L. ROOT, 1 9 6 4 )
PERCENTAGE OF TOTAL AREA
-53-
FIG 3 7 ESTIMATING BAUME RELATED TO POND AREA
(SOURCE GAR RETT RESEARCH,1969)
m
4
PE R C E N T
-54-
FIG .3B
COMPOSITION OF SEAWATER BRINES
(SOURCE - PL ANCK, *958)
-5 5 -
- - iCtlCn
further
ìS k l * o S
evaporated
chloride
Other
and
ìTù a c u
Bejond
38*
magnesium
I.
T h e ino t h e r l i q u o r i s
when a mixture of sodium chloride,
carnallite called mixed
potassium salts
are kainite,
Sax t
II i s o b t a i n e d .
p r e c i p i t a t i n g b e t w e e n 3 6*
schoenite,
Be,
salt
glasserite,
chloride with a
Be a n d
sulphate and
the mother liquor consists
p o t a s s i on
38*
Be
langbeinite.
predominantly of
small proportion o f bromides.
This
is c r y s t a l l i s e d a s bischofite.
Underground
brines:
The
salinity of
than that of seawater
Underground
oceans
brine
s o n e t Lives a s
is considered
deposits.
There are
underground
similar
to be
seawater cut o f f
The
covered by
also brines
formed
by the
by periods
flow o f
salt
The composition of
underground brines
deposits.
varies
co m p o s i t i o n of b r i n e s close to sea c o a s t s is
to seawater
evaporated
to the same concentration
Sometimes the calcimi
In o t h e r cases the
o f seawater.
from
further geological
v o t e r amongst weak
minor variations.
hi^ver.
much a s e i g h t times.
by early geological changes and concentrated
of sunlight befo r e being
widely.
underground brines is much higher
with
sulphate content is
KCl:NaCl ratio is h i £ i e r t h a n that
In c e r t a i n i n l a n d
underground brines,
potassiun
-5 6 -
a n d m a g n e s i un
salts are totally
absent and
sodium
s u l p h a t e is
the o n l y constituent other than sodium chloride.
Underground brines occur
very shallow levels
metres.
of 3 metres to depths
Underground
Salt
process
from inland
As
tion
of salt
lake.
Salt
the earth
such
off
the
lakes are
from
of
an
found particularly
been derived
subject
waters a r e characterised
earlier
chemistry
by
An
alternative
era.
such
in
Salt
semi
a portion of
arid
areas of
The s a l t s o f
sea being cut
s o l a r heat.
by t h e
method of
In s u c h
presence of calcium
formation is
said
to
a depression over rock salt deposits
lakes could
igneous rock
cases,
will b e
in
formation of the
evaporation.
to concentration by
water collected
In
brines the conposi-
by geological u p h e a v a l s i n t h e p a s t and
from sedi m e n t a r y o r
areas.
underground
low rainfall and h i g h
and magnesium.
be
sea brine.
lakes depends upon the history of
from t h e o c e a n
cases,
similar to
lakes:
lakes m a y have
their being
s i n k i n g b o r a g e 116
to the surface and svbjecting it to an
in t h e c a s e o f
with
from
of more than 200
sources are tapped by
and punping t he brine
evaporation
at varying d e p t h s
also derive
their salinity
of the surrounding drainage
neither the canposition nor the phase
similar to sea
water.
-5 7 -
Salt
lakes can be broadly
1)
sulphate
2)
carbonate type
classified as
type
3) b i t t e r n t y p e
4)
In all
have
types
derived
sodiun
Sulphate typ e l a k e s
their s a lts from
rodcs and contain
sodiun carbonate
surrounding
Sanbhar Lake in
Carbonate type
sulphate.
type
sodium chloride is present.
sodiun sulphate.
type.
chloride
in addition to
Searle* s Lak e
one
such
chloride
sulphate
lake.
lake
different
in the U S A is a
of this
Salt L a k e o f t h e
'teble 3.5
sodiun
c a r b o n a t e lake.
magnesium than
similar in conposition to
sodium.
The Dead
USA is
They
Sea
is
a sodiun
sea brine of an
gives t h e c o m p o s i t i o n of
lakes.
Lake
sandy,
sodiun chloride and
free but contain calciun.
The Great
identical density,
is an example
lakes are alkaline lakes which contain
Bittern type lakes contain more
are often
India
salty or
brines may also
mud c a ked
form
over playas which
floors o f d e s e r t basins.
are the
TABLE - 3.5
COMPOSITION OF DIFFERENT LAKE BRINES (X BY WEIGHT)
Great Salt
Lake USA
ELEMENT
Searles
Lake USA
(dry lake)
Dead Sea
Israel
Andhoql
Lake
Afghanis­
tan
3.13
11.76
1.07
Sea
Water
Sodium (Na)
7.00
Potassium (K)
0.50
1.93
0.52
Trace
0.0*1
Magnesium (Mg)
0.70
—
2.93
0.90
0.13
Calcium (Ca)
0.03
—
1.13
0.02
0.0«
15.**3
18.56
1.93
0.38
—
0.007
Chloride (Clj)
Bromine (Br)
1*1.20
—
10.9
12.26
—
Lithum (LI)
0.003
—
—
—
Trace
Boron (B)
%
Sulphate (So^)
0.003
0.01
—
—
Trace
5.12
0.07
2.96
0.26
2.39
—
0.007
Trace
Carbonate (Co^)
1.75
—
-5 9 -
CHAPTER - IV
EVALUATION OF POTENTIAL
SOLAR SALT SITES
Although a country may have a long coastline or inland
lake shore line, not all locations along the coast or lake
shore become automatically suitable for manufacture of solar
salt.
There are a number of factors to be considered before
setting up a solar salt plant.
The effects of these factors
may have to be studied for periods ranging from three months
to a few years.
Sometimes any one of the factors may turn
out to be critical.
However, for a solar salt works to be
technically and economically viable, all the important
factors must be at least reasonably favourable.
(i)
(ii)
(iii)
(iv)
(v)
Availability of low cost land and its topography
Use of Landsat imagery to evaluate potential
sites
Accessibility to the market and competitive
factors
Soil conditions
Procedure for determining solar salt making
capability of a site
(vi)
Availability of seawater/brine and its salinity
(vii)
Susceptibility of the area to storms, flooding,
and runoff
(viii)
Availability of infrastructure facilities such
as electric power, fresh water, and labour.
Ideally, the location should be a flat or gently sloping
block of impervious clay land unfit for agriculture, with
A
É
-6 0 -
auwcaa
«.A
ww ak/uuuan t
. . . . . A.
A.
.
v^uanl x c ic a
. £
ui
. . . J.* 1 . . A , . J
iu iu x iu t c u
. . . ____ A . _____ t
«_______ * 1
acawa L C I/ S UU5UÌ1
or lake brine, with provision for tidal intake during high
tides in the case of seawater, with little or no rainfall,
with a hot dry breeze blowing all year round, with a rail­
head or deep seaport nearby.
are rare.
However, such ideal locations
The coast of West Australia and of the Baja
California desert in Mexico, where salt is manufactured all
the year round and exported by ship to Japan, come closest
to these ideal conditions.
Usually some compromises have to
be made in the above factors and a decision taken based on
the overall techno-economic feasibility of the specific site.
(i)
Availability of Land and its Topography
Flat land closest to the sea, lake, or underground
sources of brine, unfit for agricultural or other purposes is
preferred for locating a salt works.
Land that can be used
for agricultural or other purposes is generally too expensive
to make a salt project economically viable.
The land chosen
should be flat or very gently sloping (not greater than 3u
to 40 cms per kilometre) in one direction so that it is
possible to hold the brine in ponds at different stages and
obtain an even cover with shallow depths and at the same
time allow the brine to flow from one pond, to another with
the minimum of pump stations.
To determine the area avail­
able, a traverse survey is conducted starting from one point
on the boundary and proceeding along the boundary measuring
distances and angles until the starting point is reached
-6 1 -
agdin.
The area within the traverse is planimetered,
Simul­
taneously, the levels within the area are determined within a
specified grid of say 60 H x 60 M.
This grid will vary
depending on variations in topography, existing lake or pond
areas, etc.
Points of equal levels are joined to form
contour lines.
The contour map will then determine the brine
holding capacity of the land at different levels and will
yield the data required to design the brine circuit.
Photo-
grammetric elevations are often taken from aerial photographs
at a grid of 60 H x 120 M that are suitable for site evalua­
tion purposes.
If insufficient flat lands are available, consideration
can be given to practicality and cost of constructing ponds
on elevation contours (terraced).
(ii)
Use of Landsat Imagery to Evaluate Potential Sites
Satellite imagery is an invaluable tool to select and
evaluate sites for solar salt production.
Large scale images
covering thousands of square miles can be reviewed in a
matter of minutes to select and compare sites for further
study.
Magnified and processed images in black and white
and false color provide more detailed data on site conditions
for evaluating the feasibility of pond construction at
selected locations.
Solar evaporation pond site selection is usually carried
out on a regional or country-wide basis to determine the
location of suitable land areas in proximity to transportation
*
-62-
and shipping facilities.
After initial site selection,
evaluations to obtain detailed data on geological and
hydrological factors affecting pond design and engineering
are made from field inspection.
Image processing
Images obtained by Landsat remote sensing are extremely
useful for both studies.
The unprocessed image area for a
single frame covers about 13,000 square miles.
An image is
obtainable in usable form for site selection procedures with
a scale of about 1:250,000.
The image can be rapidly scanned
to locate sizeable areas with tonal variations signifying
flat ground or low lying swampy areas potentially suitable
for solar pond construction.
landsat sensors obtain images
in four or more separate bands or wave lengths.
Site
screening and selection studies can be based on tonal varia­
tions for a single band that provides indications of soil
moisture and surrounding terrain characteristics.
A band 5
image generally gives the best display of geological .
ures,
soil moisture, and the location of the land-water interface.
Bands 4, 5, and 7 are composited to yield an image in
false color for detailed site evaluation prior to field
studies.
The variations in color and tone, on the image show
the health and distribution of vegetation, moisture content
of the soil, depth of water adjacent to the area, and site
geomorphology.
It is often helpful to enlarge or magnify
the image by photographic processing to a scale of either
-6 3 -
1:20,000 or 1:50,000 for detailed site evaluations.
Single
bands can be used jointly or separately with multi-spectral
false color to provide data on soil moisture and geomorphology.
The 4, 5, and 7 band combination provides usable
data at the least cost for both site selection and evaluation.
The enlarged imagery scales recommended for site evalua­
tion studies are commonly used as a base for topographic
mapping.
If topographic maps are available for a selected
site, a clear overlay of the map should be prepared to match
the scale of the image enlargement.
When field investigations
are implemented, features on the image cam be directly
referred to topographic map features and elevations.
It is
helpful to obtain images for a particular site during the
wet and the dry season.
Our efforts to obtain useful seasonal
data depend on not having local or seasonal cloud cover in
the area of interest at the times the. satellite image sensors
are turned on.
Sensor description and comparisons
As previously noted, Landsat images are available in
four separate bands.
The four bands designated 4, 5, 6, and
7 occur in two visible and two invisible portions of the
spectrum, ranging from green through red to near infrared.
The various sensing bands and their wave lengths are as
follows for Landsat 1 through 3:
Band Number
4
5
6
7
Wave Length in Micrometers
0.5
0.6
0.7
0.8
to
to
to
to
0.6
0.7
0.8
1.1
visible visible invisible
invisible
green
red
- near infrared
- near infrared
-6 4 -
Sub-scene images of each individual wave length from a
Landsat Multispectral Scanner (MSS) range
in tonal variation
from white through grey to black, depending upon the wave
length reflected from the object.
As stated succinctly in
Petroleum Engineer International, "these images are invaluable
to the geologist because of their synoptic aspects— a single
scene surveys a wide variety of terrain, geology and landform
types under near optimum viewing conditions that enhance or
emphasize the relationships of surface features."
Vegetation
shows up best in the near infrared and water is best indicated
in the green band.
On false color composites, using bands
4, 5, and 7, healthy vegetation appears in red and clear deep
water in black.
In a sparsely covered area typically selected
for additional study, false color variations, appearing as
red, green, and black, are used to identify or infer geologi­
cal and hydrological features impacting on pond construction
and operation.
Interpretations of favorable and unfavorable
siting characteristics are all subject to field confirmation.
Table 4.1 following is revised from a publication by
David J. Barr to illustrate the possible use of Landsat
imagery for interpreting technical and environmental solar
evaporation siting factors.
Application to site interpretation
Landsat imagery b ■'ve been used for siting studies in a
number of countries with varying terrains.
A suitable site
was located for solar ponds near a proposed petrochemical
*
TABLE 4.1
SITING FACTORS AND SENSOR USE
Siting Factor
Imagery
Satellite
Topography
I-F
Site Size
M
Existing Land Use
D
Existing Bodies of Water
D
Extent of Vegetative Cover
D
Diseased (affected) Vegetation
I-F
Regional Geology
I-F
Local Geology and Soils
I-F
Local Erosion
I-F
Deposition-Siltation
I-F
Soil Moisture Condition
I-F
Regional Hydrology
Local Hydrology
Pollutional Discharges
I
I-F
I
Lagoon Leaks
I-F
Discharge Dispersion
I-F
Flooding Potential
I-F
Key:
M
I
I-F
D
=
=
=
=
Measure
Infer with high confidence
Infer subject to field check
Detect
-6 6 -
complex on the Arabian Gulf in Saudi Arabia.
Standard aerial
photography was not available due to government regulations.
A Landsat image was readily available in band 5 and three
flat sabkha or swamp areas were identified about 15 miles
f_om the proposed complex.
The satellite image was taken
during the wet season, which assured that the areas were not
normally subject to flooding by Arabian Gulf storm tides or
seasonal surface water discharge.
One of the areas selected
for soil borings ana permeability tests had variations similar
o the tonal signature at two saline deposits about 60 miles
away.
The available literature indicated that this salt
deposit was both limited in size and thin.
Field investiga­
tions confirmed the image interpretation, revealing a large
20 square mile salt deposit.
Later drilling showed the
mineable salt thickness exceeded 25 feet.
At the other two
Saudi Arabian sites, testing showed permeability coefficients
ranging from poor to fair and a recommendation was tendered
to exploit the sabkha salt deposit.
Selection and evaluation was made of sites in Haiti and
the Dominican Republic.
A number of band 5 images for
coastal areas in both countries were obtained and examined.
Some of the preferred locations were too small to provide
the requisite salt tonnage.
Other areas had excessive water
depths behind barrier beaches with drainage patterns indi­
cat _.iv high surface water runoff.
A total of three sites
were selected for further investigation and magnified false
color images were obtained for detailed studies.
Inspection
-6 7 -
of false color image at one of the three sites selected for
detailed evaluation revealed an extensive drainage system
that was not apparent on the band 5 image or topographic map.
Through a subsequent inquiry, we found that an agricultural
land reclamation program would eventually incorporate part
of the area needed for solar ponds.
This consideration
nullified the need for additional evaluations.
Standard aerial photography and topographic maps were
available for the remaining two sites.
At the only Haitian
site, imagery studies confirmed with a field check indicated
a potential for inundation of proposed concentration and
crystallizer pond locations from storm tides and the possi­
bility of breaching the landward side of the crystallizer
dikes from flash flooding due to seasonal precipitation in
the mountainous interior.
Problems at the third site located in the Dominican
Republic differed significantly.
Comparison of the Landsat
imagery and air photos with available geologic maps showed
that the mapped boundary of a water bearing karstic limestone
was not correctly located.
After adjustment of the land
area, the facility was downsized by about 40 percent.
A
further interpretation of vegetation patterns and tonal
variations suggestive of soil moisture indicated the karstic
limestone dipped gently seaward below the site with groundwater rising near the surface through the overlying soil and
rock.
This local hydrologic condition was confirmed by
field observations of underwater springs offshore and seeps
and springs along the beach bordering one side of the site.
-68-
(iii)
Accessibility to Market
Salt is a low value commodity.
In transportation to the
market the freight element becomes an important factor.
Therefore in order to be competitive, the salt works should
be located close to the market or to a large seaport or rail­
head that will enable the salt to be shipped in bulk quan­
tities.
In some cases, this becomes the overriding factor
in determining the location of the salt works. Potential
long term freight rate and fuel cost changes must be evaluated.
(iv)
Soil Conditions
Brine in a salt works is held in large ponds with earth
bottoms and allowed to concentrate by solar evaporation.
The characteristics of the top one metre layer of the soil
determine the capacity of the land to hold and evaporate
brine at different stages of concentration.
A prime indi­
cator of the nature of the soil is its composition expressed
in terms of percentages of gravel, sand, silt, and clay.
This composition is determined by mechanical analysis.
Obviously, a gravelly or sandy soil through which water
seeps through quickly is not suitable whereas a clay soil
which is impervious is suitable.
It is recommended that
insitu percolation tests be made where percolation rates are
questionable.
However, too clayey a soil will be weak under
wet conditions and will impede proper harvesting of the salt.
Also clay soil tends to crack under dry conditions.
a soil the presence of fine sand imparts a desirable
In such
i
-69-
characteristic viz., increased bearing strength.
Ideally the
soil should comprise of a good mixture of sand, silt, and
clay with sand content not exceeding about 40 percent (as
fine sand) and the balance being accounted for by silt and
clay, clay being more than silt.
In order of preference,
clayey soils, clay loam, and silty clay are suitable for
establishment of a salt works.
Such a soil would fall under
the groups ML, CL, MH, CH of the Unified Soil Classification.
In a d d i t i o n
properties
of
the
to
the mechanical
soil
are
analysis,
certain
index
to b e measured:
Name of Property
Desirable Range
Proctor compaction
a) Max dry density
b) Optimum water content
1.5 to 2 gm per cc
16 to 25 percent
2)
^'oid ratio
0.6 to 1
3)
Permeability
3 ems to 7 ems per year
4)
Compressibility
_
a) at 1.5 kg per cm
b) at 3 kg per cm2
1)
1 to 2 percent
2 to 4 percent
The bearing capacity of the soil is to be determined
from the point of view of assessing its strength and suit­
ability for construction of roads and embankments. A bearing
2
capacity of at least 1 kg per cm is required. If lower, it
should be improved by addition of sand and gravel on the top
of transport roads and by addition of sand* during the prepar­
ation of erystalliser floors.
The consistency limits of the soil should also be
determined as these data are useful in the compaction of
erystalliser floors and in the construction of embankments
I
-7 0 -
to achieve the desired strength.
These consist of the liquid
limit, plastic limit, plasticity index, and shrinkage limits.
These limits are easily determined by simple laboratory tests.
The procedures are described in any standard book on soil
mechanics.
The ideal ranges for these consistency limits
are 40 percent to 60 percent for liquid limit, 15 to 30
percent for plastic limit, and 15 percent to 40 percent for
plasticity index.
In such soils the plasticity limit is
generally much greater than the shrinkage limit which shows
that the soils are mostly fine grained plastic soils.
Field
inspection
Thorough site inspections are required for many purposes:
(v)
1)
Signs of sub-surface fresh water flow
2)
Potholes or sinkholes
3)
Location of seepage areas
4)
Consistence of soil conditions
5)
Evaluate vegetation for potential seepage or
infiltration
6)
Geological classification and evaluation
7)
Areas suitable and unsuitable for dike and
crystalliser pump station construction,etc.
Procedure for Determining Solar Salt Making Capability
of a Site
Meteorological studies
The meteorological measurements recorded at the area
serve to measure the factors affecting the salt making
capability of the area.
If the data is not readily available,
-7 1 -
u ic
iv x x u n x u ^
lucucuxwrxu^xwox
xiiowx uiwriiwa o x c
ocw
u y auu
recorded for at least one year and more if highly fluctuating:
Instrument
Parameter
Wet and dry bulb
temperature and humidity
7 day relative humidity
recorder
Maximum and minimum air
temperature
M a x i m u m and m inimum air
thermometer
Wind direction
Wind vane
Wind speed
Anemometer - totalizing
Rainfall
Rain gauge
Evaporation
Open pan evaporimeter (1)(2)
Radiation
Solarimeter
(1)
This includes floating min - max water temperature,
stilling well, and hook gauge.
(2)
This is a 10" x 48" diameter galvanized class "A"
weather pan.
Procedures are well established and documented for
recording pertinent weather data.
Good judgement is required
when extrapolating historical data from a weather station to
apply to a prospective solar salt site.
The weather can vary
drastically within a few miles and serious mistakes have been
made in attempting to extrapolate data from one area to
another.
Evaporation
The starting point for determining salt production
begins with the measurement of fresh water that evaporates
per 24 hour period measured in millimeters from a 48”
-7 2 -
diameter/ 10" high galvanized pan placed on 2" x 4 " supports
at ground level called a standard U.S. Class "A" evaporation
pan.
There are also other standard pans.
In most cases evaporation data for a site being evaluated
does not exist.
Until a weather station cam be provided and
at least a year of recordings made, an approximation can be
calculated from wind speed by use of one of several formulas.
A plot of the findings of 6 different authors of evaporation
per day, versus wind speed in M/sec was assembled by Salin
du Midi.
From experience the Penman B formula E = 0.14
(1 + 0.88V)
or Sutton's formula correlates pond evapor­
ation of fresh water and wind speed.
Wind records more
frequently are available than evaporation records, i.e.,
airports and large farming operations (see
F ig u r e
4.1).
Penman confirmed that in areas having wind movement in
excess of 1.34 M/S fresh water lake evaporation was approxi­
mately equal to fresh watez pan evaporation.
Below 1.34 M/S
an appreciably lower ratio existed between ponds and evapor­
ation pans.
Evaporation factor
The evaporation factor is necessary to establish the
ratio of the evaporation of brine to fresh, water for a site.
It is greatly affected by the vapour pressure (which in
^ E = evaporation fresh water in mm/day, V = wind speed
average/24 hours as meters/3ec., D = difference in vapour
pressure between air and fresh water.
-7 3 -
FIG .41
e v a p o r a t io n
OM m e s H w a t e r
(SOURCE SALIN DU M I D I . I 9 6 9 )
-7 4 -
turn
is
influenced
therefore,
the
by Mg++ content of
higher
the evaporation
the
salinity
the brine.
F i g . 3.4 )
( Mg+ + c o n t e n t )
the
lower
factor.
Salin du Midi published data that they had gathered to
demonstrate the relationship between temperature of fresh
water, relative humidity, and of vapour pressure of brine
(vapour pressure of fresh water vs. temperature is known)
and presented a formula for calculating the evaporation
factor using a derivation of Sutton's formula.
These data
have been plotted into a nomograph, Fig. 3.3 , for ease of
use and accuracy by Dale Krmse, Ph.D., P.E., University of
Florida.
Relative humidity
Relative humidity data taken over a one year period will
provide fairly reliable data but should be recorded on a 24
hour basis.
Very seldom such data exists at a new site,
however, there may be readings taken at a nearby airport at
7 A.M., 1 P.M., and 3 P.M.
The daily mean relative humidity
will approximate the average of the 7 A.M. and 1 P.M.
readings.
The 3 P.M. reading should be discarded in deter­
mining the mean.
This relationship should be verified for
a site by using a recording relative humidity meter over a
period of several weeks.
Caution is needed in using published
relative humidity data as the observer may not have realized
the importance of taking relative humidity at the specified
time of day and in his accuracy of measurements.
The average
-7 5 -
of
the
7 A.M.
Kingston,
relative
and
and
humidity
is
By
factor
7 A.M.
use of
1955-1971 was
and
1 P.M.
having
28°C
temperature,
relative humidity
brine
28.2
With
ation
Be'
of
(28.5
3.391 m e t e r s
becomes
74
24 h o u r
percent
readings was
and
the
73 p e r c e n t
agreement.
the nomograph,
site
at Palisadoes Airport,
the average monthly
between
reasonable
for a
readings,
the mean of
average of the
which
1 P.M.
3 .3 , t h e e v a p o r a t i o n
Fig.
fresh water evaporating
of
76 p e r c e n t ,
g / 1 m g + + ) is r e a d a t
evaporation
1.87 meters
fresh water
(3.391
and
average
0.55
the
pan
percent.
brine
evapor­
salt p r o d uction
in m a n y
x 0.55).
Rainfall
Excessive
sites
must
rainfall
impractical.
be
In
remembered
to brine,
i.e.,
minus
rainfall
times
of
(gross
= net
deducting
the
rainfall)
essential,
study of
evaporation
evaporates
Errors
from gross
evaporation
high
the net
at
a rate
evaporation x evaporation
rainfall
ation minus
Careful
calculating
evaporation.
by
an e r r o n e o u s l y
solar
that rainfall
multiplying
to
makes
factor,
x evaporation
net brine
rainfall
have
been made
and
(gross
factor.
This
fop
the
Average
monthly
2)
Maximum
1 day
site
3)
Variations
rainfall
and
2 day
in r a i n f a l l
rainfall
per month
then
evapor­
evaporation.
patterns
at
calculates
i.e.,
1)
equal
factor)
evaporation
i.e.,
it
per month
is
-7 6 -
4)
Determine
if
and velocity
there
during
suitability of
Determine
6)
Evaluate
7)
-
350
365
Brine
=
0.188
M
deposited.
floating
saturated brine
to
net
=
rainfall
are pos s i b l e
1.678
M.
the
salt
remove
reducing
prystaiiisers.
(3.391
Then deduct
harvested,
for
M
x
time
and refilled
(1.678
evaporation.
illustrates
salt recovery
29.0
Be'
When
of
the
salt
dumping
(bittern)
Saturated brine
point
and
in
evaporation becomes
be drained,
operation.
shrinkage,
to
harvest
floors
in
Salt deposited
this
ponds
harvest
is
x
losses
scale
saleable.
in
losses
1.609
harvesting,
are
from
271
g/1
3,314
M
x
M
206
206
NaCl
so
g/1
ton/ha
x
that
is
in
1 0 ^ ].
106
washing,
then applied
the
NaCl
recovered
then becomes
[10,000
brine
76 p e r c e n t o f
contains
brine
from original
'
At
decants
i n tifcystaiiisers
at
percent
parallel
salt
to crystal U s e r s .
is r e c o v e r e d .
76
(evaluate
for catastrophic
net brine
3.6
crystallisers
if
if
rainfall
will
recovery
fed
rainfall,
and period
salt
Venezuela
1.609)
Figure
brine
chances
Determine
crystalliser
x
direction
automatic
and
frequency
eliminating
At Araya,
0.55)
wind
surf a c e w e a k brine)
5)
or
and after
using
in crystal U s e r s
top
is a p a t t e r n o f
to
stockpile
arrive
at
-7 7 -
Series
operation
Tests
have
been
recorded
indicating
that
approximately
10 p e r c e n t m o r e s a l t is p r o d u c e d in crystal U s e r s
them
of
in
27.6
series
Be'
parallel
from
(vi)
3 ponds
brine
of
0.55
of
28.2
to
Be'.
0.60
or
salinity
in a d e q u a t e
is a n
The
of
a
tion
a chemical
and
different
diluted
study of
times
at
the
the
during
locations
3.5°
If
there
for
is
past
history
determine
operations
what
the
Baume
has
to
of
be
the b e h a v i o u r
will
cost.
the project.
This
become
has
a
in
in
improved
its
of
sea
seawater
year.
to
estuaries
2.7
entering
through
necessary and
on
the
the
these
coast
to
values,
is
sea­
it
calls
salt works
extent
economic
is
Its
inquiries
and whether
to w h a t
at
3 percent).
system.
local
varia­
undiluted
the
this
influx of
percent
sea m o u t h
works,
tidal
to
of
the
season
seawater
due
The output of
bearing
and
Sometimes
content
the
salt
along
concentration
studied
availability
the m a n u f a c t u r i n g
case
of
brine
of
is
Baume
series.
and
dilution below
investigation.
upon
operating
salinity variation
(NaCl
appreciable
serious
dependent
Be
brine
In the
close
water
‘o
average
Salinity
intake
the
Generally
3 to
and
analysis
fresh water.
is
lower
factor
greater
throughout
factor.
involves
evaporation
9 percent
quantities
important
a
(lower m g + + ) c o m p a r e d
Brine Availability
The
to maintain
by operating
to
dredging
and
viability
at
of
-78-
(vii)
Fusceptibility
of
the Area
to Storms,
Flooding,
and
Runoff
a r e a m a y become flooded due to accumulation of storm
The
water
area
discharging
surrounding
extent of
ment
storm water
from
aft e r year.
data a
the
Other
level
Therefore,
be
have been
the
other
factors
to
in the
salt works
year
catchment
area
the
extent
and
in
the
can be
into the
the
of
avoided
co-related
of water
channel
may
sea
to
or
lake
since
the
area.
designed
With
this
to d i v e r t
or an
adjoining
area.
factors
influence
cases,
solar
found
marshy
of
to
numbers,
township
be
and
ecological
l o c a t i o n of
lands
salt and
a
as
chemicals based
on
homes
in
for
these
Availability
of
rare
pumping,
facilities
for
the workers
locating
a
is
skilled
for
in
birds.
areas
power
considered
solar
identified
salt works
to b y ecologists.
basic
the
to be w i n t e r
development
sufficient
and
due
salinity
through
In c e r t a i n
water
area
embank­
be
several other
that
being objected
in
the
boundary
should
determined
for p r o d u c t i o n o f
bitterns,
type of
Factors
considerations
salt works.
the
The
areas
purpose,
directly
passing
There may
labour
ir
large catchment
rainy months.
Inundation of
the
suitable boundary
river without
ideal
this
approximately
storm water
(viii)
determine
adjoining
removes
rise
usually
especially during
the
For
corresponding
from the
required.
completely
must be
it
it
flooding will
protection
this
into
and
fresh
are
salt works.
-7 9 -
From these
the
factors
quite
tive
up
affecting
demanding.
effects
observations,
the
However,
can be
it w i l l
location of
by
careful
be
a
solar
and
that
salt plant
analysis
considerably reduced
in l o c a t i o n s p r e v i o u s l y
appreciated
their
restric­
salt works
considered unfavourable.
are
set
-80-
CHAPTER
- V
SMALL AND MEDIUM SCALE
Design
and
layout
Today
o f the
one end
using
types o f brines
from the m o s t p r i m i t i v e
of the
labour
scale salt is
other end there are very large
mechanised
design and
The
r a n u f a c t urine
cost,
tive
adopt
scientific
is
aim
plants
f or
employing
small
to medium sized
methods of quality control and
labour.
financial
from an e m p l o y m e n t view
solar salt
point.
nanufacture
agriculture-type operation and mechanisation
and e c o n o m i c problems.
employment
in
solar
salt
works
a selec­
The degree of
nust b e carefully considered n o t o n l y
social
fully
is to o u t l i n e
mechanisation
developing countries
the
quality product at minimum
mechanisation without displacing
but
At
produced and handled
of the guide
a high
At
inits
quality control and
-actices
operations that will produce
a r a n g e of
to the m o s t advanced.
solar salt
naterial
completely by machines.
by adopting
wit h no quality control.
of production and
so t h a t t h e
solar evaporation of
manufactured in cottage
intensive methods
m o d e r n methods
SALT
salt w o r k s :
salt is m a n u f a c t u r e d b y
seawater and other
techniques
PRODUCTION OF
from the
In m a n y
is
is
a traditional
likely
Often in these countries
is c o m p l ementary
with
to
raise
— o JL”
agriculture.
Nevertheless with the growing
quantities and
applications
a h i gher purity of salt
in all d e v e l o p i n g
gradual
shift
in siz e of
scale.
Also,
existing
more
productive
terns
of its
considerably,
Chapter
total
from c ottage
salt works
of a
salt
frequently
works could be
outp u t a n d i t s area.
depending
upon the
Production
several
IV a n d c o u l d b e a r y w h e r e b e t w e e n
evaporation and
salt,
can
scale to
a
small
be made
of
and harvesting.
size
exceptional cases,
with
there has to b e
by the application of n e w techniques
evaporation control
The
solar
for larger
for i n d u s t r i a l a n d t a b l e
countries,
operation
demand
and
250
the yield could be
yields
in
vary
factors outlined
in
10 tonne sA^ectare o f
tonnes/hectare.
vhere the feed brine
considered
In c e r t a i n
is almost saturated
e v e n higher.
-8 2 -
Yield
potential
The
net brine
of
the
yield potential
evaporation rate,
See Chapter
IV
The
of
the aren depends
upon the
intake brine salinity and
seepage.
for c a l c u l a t i o n procedure.
Ratio of crystallisers
ponds
area;
to evaporating
ratio of
is d e t e r m i n e d
as
ponds:
crystalliser ponds
to concentrating
follows:
Integrated average evaporation r a t e o f b r i n e
i n t h e d e n s i t y r a n g e o f 3* B e t o 2 5 . 5 * Be
6 0 0 nun/year
Integrated average evaporation r a t e o f b r i n e
i n t h e d e n s i t y r a n g e 2 5 . 5 * B e t o 30* Be
400 mm/year
Weight percentage of water
b e t w e e n 3* B e a n d 2 5 . 5 * B e
90
Weight percentage of
b e t w e e n 25.5* Be a n d
evaporated
water evaporated
30* Be
6.7
I f Aj i s t h e c o n c e n t r a t i n g a r e a a n d A 2 t h e c r y s t a l l i s e r
a r e a t h e n t h e a r e a r a t i o is g i v e n by
90
A1 x 6 0 0
a 2 x 400
90
A1
a 2
Pond
layout
based
area.
6.7
design
The
6.7
x 400
x 600
60
9
677
I
guidelines:
laycut of
ponds
and brine
flov
largely on the elevation contours and
The c o n c e n t r a t i n g
ponds
a r e trade
as
circuit are
topography of the
large
as
is
-83-
consistent with maintaining
venting the
forration of dead areas o r 6hort circuiting.
a r e normally
weirs and
the desired pond d e pth a n d p r e ­
worked
gates
in
series.
nust be
To b u i l d
In t h e c a s e o f
reservoir area
may b e restricted
maximum
advantage
of
tidal
concentrating area are
up a g r a d e d d e n s i t y ,
provided to enable control
b e t w e e n ponds.
inflow.
2 or
the concentrating
gypsum
ponds)
is a t about
6*
raised
t o 24*
Be.
is arranged
tance,
flow p a t h
as b rine
is m a d e
expenditure
incurred
the
ponds
to travel
the
in
zig
the
size
ponds
longer d i s ­
in
of the r e s e rvoirs
the partition bunds
zagging t h e brine.
containing brines of widely
infiltration of
adjacent
different
to each other
the weaker b r ine
pond containing t h e concentrated brine.
topography of
over a
for c o n s t r u c t i n g
densities are not normally located
because of possible
increase in
a balance ha s to b e struck between th e
advantage accruing
Concentrating
in a
mixing o f b r i n e of
the progressive
In d e c i d i n g o n
ponds,
and
spreading the b r i n e
evaporates more quickly than
and concentrating
to b e
area (including the
of the brine in the concentrating
in motion
stagnant condition.
by
prevents
thus helping
so t h a t is
3 parts to take
Be a n d t h e c o n c e n t r a t i o n i s t o b e
This is achieved
n u m b e r o f coirpar t m e n t s w h i c h
The
the
smaller t h a n t h o s e i n t h e r e s e r v o i r
The b r i n e e n t e r i n g
density.
flow
The c o m p a r t m e n t s i n t h e
area.
different densities,
of
seawater the division of
to o n l y
These
However,
l a n d d o e s n o t p e r m i t this,
into the
%*ien t h e
they a r e separated
-
fran
each
Figures
salt
other by
5.1,
5.2 a n d
5.3
well
-
compacted
give several
embankments.
layouts
of several
solar
works.
In
is
strong,
84
the case of
small
and median
sufficient to restrict depth to about 60
voirs,
about
30
ems
However,
function is to
b u i l d u p of
salinity
These are o nly
and
thumb
ponds.
shallow
it
and to
2 0 - 4 0 ems
reservoirs should b e d e e p since
store and maintain a
supply to the concentrating
salt w o r k s
eras i n t h e r e s e r ­
in t h e c o n c e n t r a t i n g ponds
in the crystallisers.
their main
sired
steady
Large depths
depths may
rules based o n
brine
slow d o w n the
result
i n d r y i n g up.
working experience.
Other general
guidelines are
a)
The brine
flow s h o u l d t a k e
b)
The brine
flow
maximum advantage o f
gravity.
the
prevailing
wind
during the
should be
in the d i r e c t i o n of
operating season as
far as
possible.
c)
be
W h e r e d u s t storms
flanked o n t h e
a b s o r b and
The
located at as h i g h
area.
the crystal lisers m u s t
by concentrating
ponds to
s e t t l e t h e dust.
d)
drainage.
landward side
occur,
crystallisers
an elevation as
and
salt
stackyard m u s t be
possible to facilitate guick
T h 1? c r y s t a l l i s e r s m u s t n o t
adjoin a weak brine
F I G . 5.1. PR O C ESS
FLOW
SHEET
FOR
A SOLAR
SALT
WORKS.
F I 6 . 5 . 2 . TYPIC AL
LAYOUT
OF A SOLAR
SALT
W ORKS.
- V
COI
I
—
"
OPiN Otre*
■
UNDtPOPOUND PIPÌ
e)
have
In a l l p o n d s
the shortest
the orientation m ust b e
dimensions in the
direction
of the
such
as to
prevailing
wind.
f)
through the
The orientation must
most
g)
porous o r low
The
the
lowest
ideal
the crystallisers at
brine
from
point as
layout
a v a i l a b l e land,
ponds are located
intermixing
close
the other
as c l o s e t o t he
possible.
the
reservoirs
to the brine
extreme
in between.
one end
lying area.
crystal lisers m u s t b e
stackyard and despatch
In an
route the weakest brines
end.
avoiding
located on
intake
point and
The concentrating
This ensures
to the other
are
smooth
f low of
the p o s s i b i l i t y o f
of brines at different concentrations.
S l u i c e gates:
Where
gravity,
tide
conditions permit
sluice gat e s a r e t o b e
sluice gates
prevent
tidal
that allow
water
water
from t h e reservoirs
are preferred
located on the
that maximum
tidal
provided.
(see Figure
of
tidal
Normally automatic
from returning
5.4) .
water
of b rine by
to enter during
The g a t e s
rain creek feeding b r ine
intake
intake
during low
should be
to thp salt
is possible.
nixnber o f g a t e s i s f i x e d b a s e d o n t h e h e i g h t
tide but
The
works,
size
of the normal
so
and
-89-
FIG 3 .4
TY P IC A L
TW O
WAY C O N T R O L
GATES
-9 0 tide,
bed
level
h i g h tides.
of
the reservoirs and
The o b j e ctive is to o b t a i n t h e
the reservoirs as close to the high
Provision can be
their
pressure and period of
supports
that during
in
tide as possible.
made to operate t h e
so
maximum level
gates o n bot h sides of
t h e rains,
these gates may
operate as
flood gates d i s c h a r g i n g r a i n v a t e r a c c u m u l a t e d i n t h e
reservoirs
and preventing
reservoirs.
seasonal
C&re
tidal w a t e r
from entering
the
nust b e taken to determine th e m onthly o r
variations in tidal
action
as they
can vary
drastically be c a u s e o f local conditions.
Estimation of pimping capacity required and punp specifications:
In s e v e r a l
maximum
intake
sea salt
of brine by
tide.
plants the design
But even
in
nust permit
such a r e a s it is
rare that the b r i n e c a n travel through t h e system and r e a c h t h e
crystallisers by
g r a v i t y alone.
to supple m e n t o r t a k e t he
Suppose the
only
10,000
required
per
are therefore required
place o f ti dal
expected
year.
gates.
output of
The v o l u m e of
to p r o d u c e o n e ton n e o f
Providing
salt
is 6 0
a
sea salt works
3*
from
100-150 cubic metres.
the annual
requi~ement
is
Be b r i n e
cubic metres.
for s e e p a g e a n d r e c o v e r y l o s s e s t h e . a c t u a l
ment varies
figure,
tonnes
Pumps
Assuming
of seavater is
1.5
require­
the higher
million
cubic
-91-
metres.
If t h i s q u a n t i t y h a s
to be
punped
in
100 days the
d a i l y p u n p i n g r e q u i r e m e n t is 1 5,000
cttoic m e t r e s .
that
a day,
is
the punps o p e r a t e
20
f o r 15 h o u r s
cttoic m e t r e s / m i n u t e .
Two p u n p s
Assuming
the punping capacity
of 10,000
litreq/min are
required.
Even though
during
provision is made
for punping of b r i n e
a conparat ively short s e a s o n t h e r e s e rvoirs should b e
designed
to p r o v i d e
a
steady
supply
of
seawater to the salt
works
in t h e
event o f failure of p u n p s or
water
inflow
due
In
t o tides.
the concentrating
taken of the contours
additional
fluctuation in s e a
of t h e land
relift punping within
area,
advantage
available
should be
to minimise
t h e b r i n e circuit.
Wiile permanent type punping stations should b e
provided
punps
for b r i n e
intake
for t e m p o r a r y
for d r a i n a g e o f
few p o r t a b l e
recommended.
transfer operations b e t w e e n ponds
Axial
high
volume
centrifugal
fL o w o r c e n t r i f ugal
iron construction are commonly
a punping
d o not
need
or
ponds.
Low head
of
a
with diesel engines o n trolleys a r e recommended t o be
available
cast
and t r a n s f e r ponds,
station
priming.
is shown in
Mixed
flow
used.
Figure
and
mixed
A
5.5.
other
punps are
flow p u n p s o f
typical
Axial
elevation
flow punps
centrifugal
punps
Figure 5.b
ELEVATION
OF A PUM PING
STATION
MICROCOPY RESOLUTION TEST CHART
N A T lO N A l
HURÍ ЛИ ГН
S T A N D A R D M í t t MF N M f
i
iAn s i
. in r i r ; o
íf ',r
î A M M A R O '.
M ARM AI
í ;h a
¡
-ю
tO tn .i
.’ i
-9 3 need
priming.
Priming can be d one by
pump suctions or
shows
an
tions
where
coupled
The
intake
by using vacuum
brine punp
available,
enclosed
inpellers s h o u l d b e
of open o r
caused by
cast
2% n i c k e l c a s t
iron with a
While
salting
is
must have
lifting
frequently
provision
salting.
5.6
sta­
punps can b e directly
sguirrel cage motors.
Pumps
are usually
made of
iron casing and suction
concentrated brines above
a problem.
the
semi-open construction to
Punps
for periodical
impeller to clean
o ut t h e salt.
should
be made of bronze
preferably
Figure
For permanent
far. c o o l e d
prevent clogging
footvalves on
priming punps.
installation.
pow e r s u p p l y is
with totally
fitting
20*
Be,
for s u c h a p p l i c a t i o n s
flushing
of
the casing
Fbr t h a s e p u n p s t h e
with
flare.
and
inpeller
stainless steel
shaft.
Design
of c r y s t a l l i s e r area:
The crystallisers where the deposition of
takes
place a r e t h e
important part of
than
8%
the
of the salt
prqportion
most
productive and therefore the most
salt works.
works a rea
in t h e c a s e o f
underground or
g i v e n b e l ow:
salt
lake brines.
crystalliser area required
is
salt
They
constitute not
for s e a s a l t
works based
works and
less
a lii^ier
on-richer
An approxinate estimate o f
for d i f f e r e n t
feed brine salinities
Fig. 5-6 (a) Intake brine pump installation - front view
/ f
Fig
5-6 (b) Intake brine pump installation - rear view
-9 5 -
Crystalliser a r e a as
as percentage of
total area
Salt c o n t e n t o f feed
b r i n e (% N a C l )
3
8
6
16
10
24
15
40
20
70
25
90
Since t h e crystalliserc a r e
concentrated
be
brine
iiqpervious.
uniform
in
in the salt works,
a nd e v e n in level.
dated a n d n e a t l y imintained.
mise
is a l i g n e d
evaporation.
the degree
on
the
very
incidence of
limit
large.
in h a r v e s t i n g
rain during
is done
the wind to maxi­
and handling o pera­
followed vhich
in t u r n depends
the manufacturing
season.
If
iranual l y t h e c r y s t a l l i s e r s c a n n o t b e
siue
about 100
would be
H x 3 0 N.
30 M
x
15 M a n d t h e u p p e r
If t h e h a r v e s t i n g
sani-mechanically
or mechanically
running
tc several hectares,
sometimes
are well consoli­
The sh o r t e r dimension o f the
of feeding
A minimum
would b e
The beds
in shape,
The s ize o f t h e c r y s t a l l i s e r s d e p e n d s u p o n
method
the harvesting
in t h i s a r e a h a s t o
in the d i r e c t i o n o f
of mechanisation
tions and the
soil
with the most
The crystallisers a r e rectangular
sire
crystalliser
fed
is done
t h e c r y s t a l l i s e r s a r e larger,
tfenual h a r v e s t i i n g
-9 6 -
involves removal
veying
of
is a r d u o u s a n d needs
a d h e r i n g t o it.
employment
and
However,
tonnes per
mechanical
a salt
Standard
year).
A
harvesting which
transferring
skill to collect
the salt without
in many c o m t r i e s
%orks h a s
it is
to be
a source
sufficiently large
it to
procedure
variety of techniques
consists of
different depending
support is
been
used.
salt
floor
on many
Salt
the salt and
solid,
as
little as
Vtiere r a i n m e l t s t h e
is d e p o s i t e d
salt
f l o o r is
f l o o r s thiclciess i s
1 to
equipment
2"
salt
vfriere
floor has
floor e a c h r a i n y s e a s o n
e a c h year.
and economical.
a
factors b e s i d e weather,
procedure that most ealinas h a v e
feasible
for
a conveyor.
permit,
i . e . , ground support, h arvest a n d hauling
ground
exist
(about
for h a r v e s t i n g
preferred b e l o w t h e n e w c r o p salt.
widely
scooping
a truck/trailer through
Where weather conditions
be
and con­
justify investment in mechanical harvesting machines
40,000
the
shovels
should not be disrupted.
Normlly
to
and
it to t h e n e a r e s t t r a n s p o r t r o a d s i n b a s k e t s o r sacks.
Th e work
mud
of the salt w i t h p i cks
Following
found
a thin
is an outline of
f r o m e x p e r i e n c e to
-9 7 -
1.
ALGAL
SPLIT
W here rainfall does not
floor o v e r t h e c r y s t a l l i s e r b o t t o m ,
prevent
salt
from adhering
create an algal
minimizes
filling
P.P.M.
is
20-30
and d i r t
a p r o v e n t e c h n i q u e to
from
is
a d d e d a n d vrtiile
the rate of
During t h e r a i n y season
a b o u t 0.7
a
slime o f algae
season is ove r t h i s b r i n e is
salina and crystallisers are
brine.
This
the crystallisers.
Be b r i n e
phosphate at
W h e n the rainy
to the
saturated
salt
to the crystalliser bott o m is to
cm of 10-12
to t h e brine.
returned
voids
rode
add diammoniun
created.
a
slime o n t o p of t h e c rystalliser bottom.
pickup of
After harvest
permit maintaining
This procedure has
charged
the advantage
with
to plug
off
in s u b s u r f a c e a n d r e duce s e e p a g e in n e w l y constructed
crystallisers.
2.
SALT
SPLIT
A
salt
unsaturate 1 b r i n e
surface
a
12"
This breaks
will
has been
made,
second,
by
the
over
(bond)
3-meter wide
then,
the
over the
etc.,
to the
salt
splits.
floor.
No
floor by
pulled by
adding
floor.
1/2"
or
a
farm tractor.
so t h a t t h e n e w salt
on repeated harvests,
s u r f a c e until
salt
salt
and then dragging over the
up sharp edges of crystals
stick
formed
on
to t h e surface,
H beam
not
dragged
split is mad e
After the
the beam
so o f pew
first split
is not
salt h a s
w e a k 1-rine i s n e e d e d
for
3.
DRAINAGE
W h e n t h e salt
depth has
th e crystalliser is drained.
shallow
drains
Cat 120
6).
of a grader
and additional
cake
so that
the grader
3 days on a 20 ha
equipment can travel
is
To
used
is e x c a v a t e d
between
from end to end
The
drainage provided near
crystalliser to
o n salt bed.
to expedite drainage
inparove d r a i n a g e ,
(as a
operation.
gate when fine d r i f t salt h a s b e e n deposited.
is u s u a l l y
4.
the blade
is complete,
This is performed i n s e v e r a l h o u r s
time
wide
t h e d e s i r e d depth,
Before draining
are prepared using
draining then proceeds
drain
reached
often
Drainage
firm u p salt
During harvest,
w h e r e needed.
a swale about 4
in a
meters
crystalliser bottom
gates.
SCARIFYING
In
advance of
(with scarifying teeth,
tires)
in o n e
the harvestor
a Cat
side shifting blade,
operation scarifies the
salt
at the same t i m e t h e b l a d e o f t h e g r a d e r
salt
left b e h i n d
harvester and
on t h e salt
floor by
120 6
and
16
or equal
x 24
wide
to be harvested and
is angled to pick up
the previous pass of
places it on top of t he salt
making
the
a windrow.
This operation assures that the harvester
is
at
t he salt drastically
full capacity.
reduces
Scarifying
(loosening)
the w e a r and tear on harvestors.
always operating
-zy-
5.
HAPVESTING
It
to
cut t h e n e w c r o p s a l t
pulling
tired
trade
floor w h i c h r e q u i r e s
or equal.
life reasons.
salt
harvesting
operation
each
year
floor or
for s h o r t p e r i o d
Scarify salt w i t h g r a d e r a
path
of the crystalliser.
width
end
loader to be
A
rubber tire
This
the
length of
a
6‘ -
8'
as
a Cat 966C)
requires
10 -
12 m e ters
will depend o n
front e n d loader t r a v e l i n g at
scarified
salt
and
windrow o n top of n e w c r o p of salt
the crystalliser.
passes depending o n size of
of
used.
cross direction to path scarified picks up
it into
clay.
fir m e a r t h e n base)
2.
front
as
mechanical
Drain crystalliser.
3.
deposits
soft such
1.
wide the length
vbere there
plants where amortization of
is c o s t l y a n d
(salt
effort should
always b e done
for e c o n o m i c a l
for small solar salt
for l o w o u t p u t
rubber
rubber tires and
f l oor a n d c r y s t a l l i s e r b o t t o m is
equipment
of
Every
h.p.
is
for maintenance cost and
This c a n n o t
guidelines
When salt
a low cost 70
a harvestor moulted on
mounted harvestors
Some
size
is n o t d e s i r a b l e t o t r y
farm t r a c t o r c a n pull t h e harvestor.
equipment
is n o
D-6
which loosens u p t he salt,
made to u t i l i z e
avoid
it
from t h e sa l t
the harvestor with costly
scarified,
be
has been proven that
This will
bucket.
require
for a 3 4 4
2 passes and moves
M
2 or
bucket
3
(such
a b o u t 2 4 0 M/hr.
-100-
4.
An
trucks or trailers
loader trailers
from the
are end or
tractor either singly o r
and
can be built
axle
in ary
equal o r
windrow.
These 10
side dump
by
and
avoid
- 15 t o n paya
farm
Such t r a i l e r s a r e s i m p L e
local
fabricators.
bushings a r e recommended a s suitable
20 KM/hr.
loader t h e n loads
trailers pulled by
in tandem.
country
t h e same
Bronze
for l o w speed
t h e corrosion problems
of ball or
15
-
roller
bearings.
Operations
alternate shifts
to
2,
3 and
4 can be performed on
minimize equipment requirements.
Loading
contract trucks on
number
and trucking
is o f t e n
a second shift
feasible using
vhen trucks are normally not
used.
The
salina
equipment
performing
rubber tire
to move
e a r t h work,
front end
bulk salt,
lifting,
loader
is b a s i c a l l y e a r
load hqppers,
etc.
- not
just
and
the highly
costly annual
Construction
corrosive
action of
salt
in
for harvesting.
Conventional specialized harvestors a r e generally
t h e time
and
idle m o s t of
requires
maintenance.
of
the
salt
works;
Emba nkments:
The
ring
channel
salt
works
to protect
it
is b o u n d e d b y
from storm
an embankment and a
«ter
flowing
in
from the
out dump
-101-
ad joining
board
of
area.
c a t c h m e n t areas.
The
top
w i dth and side
of 5 M
is
lake
peak
slopes
or river.
the boundary
The
width and
rainfall
height
slope to d r a i n
recorded
and
on
the height
of
about 60
in t h e a r e a
wave
concentrating ponds
bunds.
of w a t e r to be
cms.
action
a
If
road a minimum
top
excessive
a n e a r b y creek,
designed with suffi­
water accumulated
for a
24 hour
by a
period.
bunds separating different
need
not be of
as great a
stored providing
also
serve
as
restricted
free board
to about
inspection roads
5 metres
embankments are
for a
is required,
lined w i t h
in
there
loose
boulders.
Embankments are constructed
adjoining b o r r o w areas,
typical
cross
in Figure
sections
are
shown
ring
Their heig h t can be fixed based
minimum top vddth o f
is
off
Their top width c a n b e
e x c e p t w h e r e they
which case
bund.
water into
ring channel m u s t b e
as th e boundary
3 metres
the embankment m ust be
embankment perimeter runs a
The internal partition
reservoirs
of
to act as an in s p e c t i o n
to divert catchment storm
cient bed
free
is required.
Along
channel
a
flood level r e c o r d e d in the
provide the required strength to the
embankment
width
embankment must have
1 M a b o v e t h e h icjiest
sufficient to
the
The
from e a rth
from
enbankment and borrow pit
5.7,
2 to 3H
-102-
I
c) B oundary
SM
em bankm ent
1
\ '///////>^^F7777
.Side slo p e 1:2
G ro u n d le v e l
b)
In te rn al
embankment
(cu m
road)
3M
Side s lo p e 1*2
V Ground le ve l
c)
In tern al
em bankm ent
F I G . 5 . 7 . T Y P IC A L
EARTH
(N on
vehicu lar)
EMBANKMENT
CROSS SE CTION
-103-
W h e r e labour
structed
h_nd
manually in layers of 15
drawn
rollers
onbankment.
used
is cheap,
to provide
embankments may
- 20
cms a n d conpacted
available
bulldozers c a n be
to scrape o ff adjacent earth on both
tion required
slopes
is
thorny
bushes
sides to
form the
r u n o v e r i t t o c o n p a c t it.
is d e t e r m i n e d b y
A
The conpac-
the soil bea r i n g capacity.
cheap and effective
to p r e m o t e s h r u b
way of protecting
growth along
the
sides.
the bund w i t h paddy
anbankment
Certain
like proscopis g r o w q u i c k l y in s a l i n e
Sometimes dressing
by
the requisite strength to the
Wiere equipment is
embankment a n d t h e n to
be con­
soils.
grass mixed w i t h mud
is
also helpful.
Are a s w h e r e top
sand
occurs
over an
impervious
layer b e l o w resulting in h eavy percolation,
can be
used by
impervious wall to
seal
forming
wells
In
to the
digging
5.9).
trench of
off cross percolation
Shallow open
close
a key
clay
from the
However,
pond
(Figure
5.8).
and b o r e w e l l s ;
areas where concentrated
surface u p to a d e pth
shallow
and an
productively
open wells
of
about
%#ien t h e b r i n e s a r e
brines are available
o f 8 H,
10 -
these are tapped
15 M d i a
(Figure
available lover down and
by
- 104-
FIG 5 . $ . PRE VENTION O F C R O S S
EMBANKMENT.
SEEPAGE
AC ROSS
- io s -
FIG . 5 . $ . T Y P I C A L CROSS
B R IN E W E L L .
S E C T IO N
OF
AN
OPEN
“lun-
whe n the b r ine t a ble tends
to fall
to sink borewells. • This c o nsists
e i t h e r by
The
25
using
diameter
cms.
in drilling
a hand auger or by
to
sink
casing
borewell.
in
pipe
can be
However,
required
High
to
weak and tends
used
Density
Figure
3 0 0 M.
it
water strata
is reached.
the
portions where cross seepage
feed t h e borewell,
Polyethylene.
to collapse,
for th e upper portions o f
slotted casing pipes are
C h s i n g pi.-*es a r e o f c a s t i r o n ,
Polyvinyl
Chloride o r
A borewell cross section is
shown
5.10.
vary
in d e p t h
from about
20 M t o o v e r
water table should not d r o p b e l o w 8 M
The
continuous
pumping
operate,
there
necessary
to
exceed
to
s u p p o r t t h e s i d e walls.
until th e
in the lower
Borewells
are
using a pneumatic drill.
casing pipes to
The drilling should continue
used.
a hole vertically
W h e r e t h e e a r t h is firm n o c a s i n g p i p e i s p r o v i d e d .
is necessary
is
it is a d v i s a b l e
of t h e b o r e is n o r m a l l y i n t h e r a nge of 15
But lower d o w n w h e r e t h e soil is
Solid
i n simmer,
if ordinary
centrifugal
water tables are
pumps
even
under
are to
10 M b e l o w g r o u n d level, it is
lower the pimps to a
level where suction d oes not
8 M or to u s e special deep well submersible punps which
lowered
i n t o t h e w a t e r strata.
-107-
wrXV/
W7A V A V A
Im p e rv io u s
S E C ilO N THROUGH A G R A V E L - P A C K E D W E L L .
D e p t h of w e ll
CROSS
f o r m o tio n
«w
Im p e rv io u s fo rm o tio n
CROSS SECTION OF A TY P IC A L
S O IL.
F I G . 5.10. T Y P I C A L
BOREW ELL
GRAVITY W E L L
CROSS
---------------- ►
IN HOMOGENEOUS
SECTIO N D E T A IL S .
-108-
Prospecting for good locations
for borewells
is
still
largely based on hjdrographic studies a n d systematic
trial
bore
t e s t i n g t o i d e n t i f y t h e w a t e r strata.
resistivity
very
m e t h o d s c a n n o n ly u s e d
often yield erroneous
n o t useful.
The
and borewells
widely
not
normally
the
output of
closely
be
of
a single
Salt
scope
of
Following
Hand
of
is
into
is
coupled
to
various equipnent
wash
Except,
in c a s e s w h ere
a series
to a
of
wells
s i n g l e punp.
plant o r
for
transporting
direct to stackpile.
salt as
The
does not permit detailed explanation and
various
types of equipment a nd
procedures.
an ou t l i n e for guidance.
Operation
1 0 - 2 0 kg,
(some
of t he many
rinsed while
t o u n l o a d i n g dodc.
variations)
Ifervested u n d e r b r i n e ,
placed i n t o b a s k e t s h o l d ­
in t h e b a s k e t a n d p l a c e d d i r e c t l y
flat s h a l l o w d r a f t b o a t s
pushed
100 metres a p a r t may have
wel 1 i s i n s u f f i c i e n t ,
1.
ing
very crucial
from C r y s t a l l i s e r ;
the manual
description
is
The s p a c i n g b e t w e e n b o r e w e l l s shou l d
are combined and
is h a r v e s t e d
a boreviell
less t h a n 100 metres.
There
ic
freshwater prospecting
for saline b r i n e s and are
proper location of
outputs.
spaced
Transport
figures
located as close as
varying
for
Electrical
(+ 3 0
cm deep
by
1.5
M
X
3 M) a n d
-109-
2.
salt b e d and
of
Crystalliser is drained,
lifted into wheelbarrows and transported
crystalliser where
3.
it is d u m p
loaded
into dump
ffarvested b y h a n d i n t o 5 0
on workers head
4.
drain then
shovel placed until
w h o walk
to edge
of
and transported.
Machine Transport
(loaded directly
trucks.
kg b a s k e t s a n d
placed
crystalliser.
I fervested b y h a n d o r s h o v e l ,
sacked
to edge
in
small p i l e s t o
by harve s t o r into
transport)
In m o s t a ll c a s e s
the new crop salt or
stalliser
Loaded
so as not
into end or
agricultural tractor.
tons
floor
eauipnent travel
to
above
damage the cry­
floor.
1.
an
a salt
transport
capacity
side
dump
Hiese var y i n si z e
pulling one to several units
trailers pulled by
from 4 to 15 M
at
speeds
of
10-25
k m /hr.
2.
Loaded
into bottom dump
trailers
in c a p a c i t y p u l l e d
by truck tractor
large
tractor pulling one to
earth moving
Speeds
vary
from 25
3.
boats,
single or
where boats
ing and
by
ton
a 5 t h vfteel o r
several
Cutter type
in tandem,
floating dredges
units.
pulled
by
a
loading into small
power b o a t
to the dock
into a h o p p e r for reclaim­
washing.
Locomotives pulling bottom dump
portable track above t he salt t hat is moved
proceeds
to 100
km/hr.
are dumped mechanically
4.
on
to 75
fastened
15
over t he crystalliser.
cars traveling
:s the harvestor
-110-
Salt. W a s h
Plants
T h e r e a r e roan/ v a r i a t i o n s o f
be
designed to
ments.
meet th e local conditions a n d q u a l i t y require­
The writer strongly
conclusions be
recommends
the p a p e r presented by
posiixn a n d
the practical
wash
salt
plant d e s i g n
clusters
before any
made as to what system b e used
b e made of
and
wash plants and should
Masuzawa
use of h is
(see t h e
following pages).
in a w a s h p l a n t is e s s e n t i a l
the washer
should dissintegrate this material
the
This
fier,
fed
Aikens
etc.
Figure
series.
flawed
5.11 s h o w s s u c h
The
is m i x e d
Banks
S/S m e s h conveyor
of 20-24
and
finish
a
for
a baric o f
is
but
from
screw
classi­
The crude s a l t
is
with saturated
slurry which is punped
the above devices in
The s a l t t h e n passes o n t o
f u r t h e r i m p u r i t y removal.
sea w a t e r s p r a y s
to displace
is used to
the M g + + removal.
Since the specific gravity of
certain
weed
and remove
B e s p r a y s o.i t h i s c o n v e y o r a r e u s e d
generally
or
in conventional log
a layout.
several of
wash liquor overflows.
slow moving
Mg++
tarfle w h e r e i t
into one or
silt,
lump breakers,
from th e crystallieers to form
or gravity
a
r a t e r i a l is d i s i n t e g r a t e d
into an agitated
brine
If t h e r e is clay,
spiral washers,
Breaking up
to expose impurities
maximum quality.
washers,
5th Salt Sym-
into crystalliser
to achieve
salt.
a careful study
at the
findings
design or
types
similar,
salt,
gypsun
of rock contamination such as coral
t h e a b o v e wrashing t r e a t m e n t
very costly
for
power,
or
and
limestone
is b o t h n o t effective,
maintenance a n d capital investment.
SAL? FROM
C R Y S TA L U S IN G
.A R E A
SATURATED
B R IN E TANK
FRESH SATURATED
B R IN E FR O M
C R Y S T A L L IS E R
PONDS.
2 0 * /. SLURRY TO
S TÀC KYA6Ó
AGI TATE 0
S LUR RY TANK
I
I
B R IN E
RETURN TO
C R Y S T A L L IS E R
PONDS.
W A S H IN G &
OEW ATERING
SCREEN.
W A S H C O SALT
STORAGE
Figure 5.11
LAYOUT
OF THE SALT
WASHERY
—
V. 7—
F e v i e w and
interpretation of portions
of Masuzawa
paper
Salt crystallises i n t o hcp p e r shaped crystals
(upside
down
pyramids)
regular
cti>es; t h e
and partly
liquor
In
This
There are also
cavities
which
is shown in th e
determined
quantitatively
World
Salt
by
and
tesuzawa.
inside m i n u t e
Tests h a v e b e e n conducted
the amount of
impurities which
within t h e crystal
Following
salt
works
(but d o
not
include
Yugoslavia which are
is
salt
produced
t h e range
from
gms of
Italy,
from brine
organic content) .
Sola r s a l t
1
So4 , clay
foil o w i n g d r a w i n g
the method of washing.
Greece and
a high
K,
inpurities within t h e crystals as g m s /1 0 0
from m a n y
having
Ca,
by washing and vhich remain
of
in percent of
Turkey,
i m p u r i t i e s o f Mg,
in t h e crystal structure.
irrespective
upon themselves to become
impurities within t h e crystals
can be removed
salt
grow
so d oing voids a r e developed that trap mother
containing
organics.
the brine
majority being hoppers.
The hopper crystals
enlarged.
on the bottom of
Vacuum refined
water
0.2-0.9
p o t a s s i un
0.009-0.011
magnesiun
0.007-0.013
0.008-0.012
c a l c i un
0 .009-0.011
0.005-0.012
sulfate
0.015-0.018
0.014-0.018
Symposium,
1978.
0.10-0.13
.
0.0 2 - 0 . 0 1 5
-113-
Cavities a r e easily
crystals
what
by
microscope.
i6 seen
crystal.
during
detected within individual
Fallowing is
in t he microscope
of
a sketch
solid transparent
t h e r e is an o p a q u e
layer that
ffesuzawa o f
a thin slice across a
It i s i n t e r e s t i n g t o n o t e t h a t
the daytime
by
salt
for t h e s a l t d e p o s i t e d
layer and at night a
was a b out
1/3
of the
0.24 m m total
deposited.
T h e thickness
between
of
of
layer that was
0.0 3 - 0 . 7 mm.
the 0.24 m m
crystals
indicated
that
entrapped the
Mexican s a l t h a d
deposited p e r day
made u p
opaque
of entirely
t h e n i g h t time
or
opaque
(had
a cavity
is t h e o r i z e d
it
may be caused
by
of 0.21
Salt
(maximum cavi t y situation)
deposit
that w h ere large
layer
ranged
88% of c a v i t y layer.
also
maximisn M g w i t h i n t h e c r y s t a l
It
cavities)
percentage
created
cavities and
from mother
liquor.
of cavities exist
excessive organ i c s suspended in t h e brine.
-114-
It w a s
found
that
the Mg within crystals
tional
to the percentage
was
of cavities and
directly
to the
propor­
Mg content o f
t h e brine.
Tests
ing
indicated
low Mg p r o d u c e d about
and about
1/8
of
Another
produced
from brine hav­
1/4 o f t h e c a v i t i e s a s n o r m a l b r i n e
t h e Mg or roughly
could be obtained
deposited by
that salt
0.003%
Mg.
Low Mg
by dissolving u p deposited salt
brine
from salt
f u r t h e r e v a p o r a t i o n o f b i t t e r n a n d p i c k l e ponds.
measurement
of cavities
from bot h the density a n d
the water
content.
cavity
2 .1 1 ; c m 3 d e n s i t y a n d w a t e r c o n t e n t o f 2 .2 % d o w n t o
at
Maximum
is
% cavity
is at
2.16
and minimum
0 %, r e s p e c t i v e l y .
The
Mg
w i thin crystals
(not r e n o v a b l e by
will b e r oughly
in the same relation
cavities,
0.008
i.e.,
It i s n o t
brine
tion.
salt
0.04%
fr 0 . 1 4 %
in t h e
Mg).
o t h e r uses.
stackpile
the stackpile.
and operation.
is
Ihis
produced
it is
for petrochemical
simple
for 0.44%
to m e e t a 0.04%
follows t h a t
The r e m i n d e r
It
and 0.03
possible t h a t salt
can be w a s h e d w e l l enough
It, t h e r e f o r e ,
Mg
for s a l t h a v i n g
of th e salt
Mg
washing)
equal
Mg.
from 28-29
Be
specifica­
advisable to separate
use
(less t h a n
will b e .suitable
to s e p a r a t e low
Mg
is based o n a n efficient
produced
wash
for
salt
in
plant design
-
Control
of C a t
Of
0.01%
on
plant.
depends
broken
Ca
many"
regardless
deposited
wash
115-
upon
samples
the Ca
o f t h e total
Ca.
within crystals
The r emainder
the crystal
surfaces which
Hie success
in removal
t he d e g r e e in which
open in handling at the
of
from the salt
wash
slurry in
ing
from crystallisers.
t h e Ca
Insoluble
impurity
to
Mg,
plant.
m m in
removed
in the
and insoltbles
size
and c a n b e
of the
fine s olar salt
to
espect reduc­
after washing.
success in
removing
insolubles in the
hydrocyclone
will depend o n the specific gravity a n d size
the
and
impurity
the degree to which
broken down While punping salt
the most part
out
the wind blown
in t h e h y d r o c y c l o n e .
dust c a n b e r e m o v e d
by
cavities can b e as high
biological balance,
the hopper crystals
dust particles are very
2.1
as
however,
0.14%.
R>r
fine and
the organics
insolibles
In p o n d
systsns
and clay
within the
tha t a r e in
t h e o r g a n i c s h a v e b e e n l a r g e l y c o n s uned a n d
converted
to halophilic bacteria before
thus,
inportance of successful hydrobiology control
salina.
can be
vhich c a n b e separated
The majority of
washing,
of
slurry to t h e hydrocyclone.
a specific gravity less than
the
are
impurities:
The degree of
have
vas
shaped crystals
It i s r e a s o n a b l e
0.04%
Ca
Ca as
sulfate and
less than
about
of the
a hydrocyclone because
vast difference between calciun
received
Ca,
the hopper
S O 4 2H 2 O p a r t i c l e s a r e a b o u t 0 . 1
removed
can be
was
fed
to crystallisers;
of the
_ n C-
A
ing
crude salt
punp
and
very
to break
gypsun,
dewater.
struct
up
is
salt
a
clusters,
S/S
should be
Figure
This
is a v i t a l l y
a
of
be
above any
rain
and
water.
up of water
available to c o n ­
for hoppers and
(except
on precast concrete supports
to be
widely
a l o w of 10%
from p l a n t t o p l a n t
to as high
flood
adapted.
The h y d r o c y : l o n e
16% w h e n p r o p e r l y
designed
process
and operated.
as possible.
potential,
The
base
top
of
the stackyard
well conpacted,
given a gentle gradient to effectively
A
as 30%.
washery and s t a d c p i l e is located as c l o s e t o
crystallisers
levelled
M g ++ and to
important consideration before deciding upon
about
The
the
losses vary
plant d e s i g n to be
loss
silt
5.12).
a range reported
has
mix­
inpeller
remove
for b e l t c o n v e y o r s y s t e m s
timber mounted
with
wash
is
simply
open
to
to remove
from wood w i t h concrete
Wish plant
the
a hydrocyclone
woven wire mesh
The e n t i r e s t r ucture
stackers)
fed t o a n
preferred where timber
the was h plant
sunps.
(see
with saturated b r i n e as
and
It
effective w a s h p l ant consists of
ditch should b e around the area
into the
salt.
should
properly
drain out
to prevent b a c k ­
-117-
FEED
C
R
Y
5
CHANNEL
A
T
BITTER N
L
L
1
S
E
R
1
S
E
R
1
S
E
R
CHANNEL
ROAD
B ITTER N
C
R
Y
S
T
CHANNEL
A
FEED
C
R
Y
S
T
L
L
CHANNEL
A
BI1f T E R N
L
L
CH ANN E L
ROAD
Figure 5.12 L A Y O U T
OF
CRYSTAL U S E R
ARE A
Salt
stored
of
in t he
in h e a p s exceeding
open
even up to
100
sive
it
in h e i g h t c a n b e
without any covering to
cms.
After the
t he heap.
If t h e h e a p s a r e
(where available)
or w i t h
safely
a rainfall
the top crust
the rainwater
slides o f f t h e
small and r a i n is exces­
is n e c e s s a r y t o pro t e c t t h e s a l t
covering
withstand
f i r s t shower,
of t h e h e a p h a r d e n s a n d therafter,
surface of
8 M
low
with p a l m y r a h leaf
density polyethylene
covers.
CPE RATION OF
THE SALT WOHCS :
At
sea water
or
the commencement of
is d r a w n
by punping.
into the reservoirs
The preferred d e p t h
maintained
b e t w e e n 20 cm and
depends on
pond b o t t o m elevation.
reservoirs
untxl
60
it r e a c h e s a
and
the volume
of
either by
of brine
cm.
The variation
The b r i n e remains
about
the brine gets
a density
of
ponds in t h e c o n c e n t r a t i n g area.
20
cms in t h e
carbonate
16*
of
Be a n d
calcium
charge
6*
Be
reduced
is t r a n s f e r r e d
s e t t l e s down.
transferred
sulphate
to
Between
The brine
to
is
6*
Be.
t o a l m o s t 60%
The b r i n e
the first series
cms
Be a n d
initially
10*
ponds
and
Be calciun
further concentrated to
$rps u m ponds.
in t h e b r i n e
6*
In t h e c o n c e n t r a t i n g
is m a i n t a i n e d b e t w e e n 40
final stages.
in the
inpuritius settle down at t h e
at
the depth
about
p o n d s is
largely
of t h e o r i g i n a l q u a n t i t y d r a w n i n t o t h e r e s e rvoirs.
of
season,
tidal action
in the
concentration of
During this period the suspended
bottom
the manufacturing
Here the
separates out
and
bulk of t h e
settles down
as
-119-
long
needle
ponds
shaped crystals.
The brine
intil i t r e a c h e s 24.5*
point with
stages
respect
in t h e salt
to
sodiun
retained
chloride.
Density
i n *Be
(0-40) .
deep storage pickle
ponds before
is b e c a u s e g y p s u n h a s
salting
point
than otherwise.
gypsun
Hie pickle
are cleared of
of
operation.
pond
small
all slush and well
about one tonne are
to
of
form.
of
t h e pond.
20
to 40
saturated brine and
a
the crystal­
with
thin
with
a
for this rolling
water
so as
to
upon the type of
fed
layer of
This layer is uniformly d r a g g e d
The crystallizers are
mich
compacted with the
suitable
filled
of as
the crystalliser.
Cfcst i r o n d r u m r o l l e r s
These rollers c a n b e
quantity
If
times mo r e gypsun
After t h e crystallisers a r e r o l l e d t h e y a r e
allowed
Others
passed through
will a i d d e p o s i t i o n
increase the weight u p to 3 tonnes depending
soil.
4).
fed with s a t u r a t e d b r i n e ,
addition of s and a n d rolled.
weight
Be X
use
undersaturated or h a s rapidly
it c a n d e p o s i t s e v e r a l
Before b e i n g
dead
operators
to supersaturate.
as p o s s i b l e b e f o r e t h e b r i n e e n ters
lisers
Some
filling the crystallisers.
a tendency
brine enters the crystalliser
reached
a simple
gravity.
T h e b r i n e c l o s e t o s a t u r a t i o n is
This
at different
by using
(roughly % o f s a t u ration equals
use specific
in these
vihich i s a l m o s t t h e s a t u r a t i o n
pond system is measured
glass hydrometer calibrated
a salometer
Be,
is
with
salt
a
is
ever the bed
then charged to a depth of
ems t h r o u g h t h e b r i n e supp l y channels.
As d e s c r i b e d
-120-
earlier,
the crystallisers are charged
entering the first
of
the
series
at
p ond a t 25.6*
30*
Be
added
(see F i g u r e
as an anti-caking
the heap before the
from 2 m m t o 15 m m
ing
technique.
salt
has
solar
done
few
to a
to crushing w e t
or with
additives are
ing.
Caking
reduced
nesium
tains
sodium
by
continues in
for sale.
crystals
industrial
size
salt
may
of
range
the help
added
in size
0.5
have
adding up
carbonate and
to b e
1.5%
free
tricalciun
the crystals
to
1 mm.
drier.
This
the
is
Figure
dried.
layers in the
of a rotary
0 .0 1 % p o t a s s i u m i o d i d e ,
thisulphete as
mm
5.13.
This c an be
open sun
for a
If r e q u i r e d ,
production after grind­
moisture absorption
to
operat­
R>r e d i b l e purposes,
for specialty salt
caused by
salt,
mills a s s h o w n in
by s p r e ading t h e s a l t in t h i n
hours
Drainage
salt
without crushing.
to be ground
pond
cyanide
which depends on the conditions and
done using roll crushers or pin
Prior
last
5 p p m sodium ferro
agent.
In t h e c a s e o f
can be despatched
the brine
5.12).
m a t e r i a l is o f f e r e d
After washing,
series,
Be a n d l e a v i n g t h e
Before stad c i n g about
can be
in
flowing
in
table
agents,
phosphate.
salt
is
such as
Iodised salt
mag­
con­
0 .0 1 % c a l c i u m h y d r o x i d e a n d 0 .1 %
stabilisers when
free
flawing a g e n t s are
used.
The material
despatch as shown
in
is p a d t e d
Figure
5.14.
in
5 0 / 7 5 / 1 0 0 kg
In t h e c a s e
of
bags
for
bulk trans
-
121
-
i
Fig. 5-13 Crushing of salt
Fig. 5.14 Despatch of salt in bags
Crystallìsers
Manual
collection
ready
of
salt
for harvest
In
crystallìsers
J
-123-
Transport of salt from crystallisers to
stackyard
Stacking of salt
I
I
-124-
port by
road
despatched
available
the material
is d i r e c t l y
to t h e destinations.
in 1 / 2
for p a c k a g i n g
Brine Handling
loaded
R>r t a b l e salt,
k g / ' 1 kg
Techniques
procedures,
procedures
machines are
p o l y e t h y l e n e bags.
Certain basic principles exist
handling
into trucks and
but each
nust b e established
salina
related
is u n i q u e
to brine
and
to best suit the
specific
local condi—
t ions.
Outline
1.
of Basic
Capacity
obtain
of
Principles
intake
the needed
highest
gate3 or punps
sea watei
evaporation rates
need
to be
adequate to
d u r i n g m o n t h s of h i g h e s t Be
(yearly
and
averages should n o t be
used).
2.
Provisions
are generlly
(run-back) b r i n e
as
’ ring an d after rainy periods.
counter current
would be returned
f i r s t pond,
This
excessive
flow.
The
t o t h e sea.
first pond
Second
if b e l c w
pond
would
t o drain-back
This
is
laicwn
s e a w a t e r Be
flow into
etc.
requires
dures to
advisable to be able
judgement and well
established
operating proce­
avoid o v e r reacting c a u s i n g b a r e g r o u n d
panping
costs to refurbish the pond
to
system
exist and
after the
-125-
run-back .
Double acting plywood gates are practical to use for
this purpose
3.
A
form
(see
Figure
should be prepared
r a n g e s o n \#iich a c t u a l
evaluate
4.
5.4).
conditions
weekly
measurements a r e recorded to
of salt recovery
from crystal U s e r s
5.
Decant
equipment and
6.
Value
for
feeding crystallisers) .
7.
Hydrobiology
8.
Sealing
and design of
of
ponds
level and gravity
and possible a c t i o n needed.
Procedure and results
discarded
showing desired
at
29 -
from bittern
(brine
3 0 Be) .
procedure.
deep
storage
solar pond
of pickle
(saturated brine
systan.
with algae deposits and
iiqpregnating s u b
soils.
9.
In m o s t
situations
centrators than
pond
system
it
is
crystalliser
far
less expensive
ponds roughly
should be designed
to provide
to build con­
1:30,
an e x c e s s supply
pickle over t he basic crystalliser requirements.
several
be
techniques to maximize
discussed
Ratio
further.
various
the brine handling
technique
flow b r i n e c o u nter
currents
for
improving
effective
solar h eat
of
There ar e
factors.
to C rystallisers
To determine this consideration
vision
the
crytalliser production that will
These d e p e n d on
of Concentration
therefore,
to be
used,
nust b e
such
given to
as ability to
during a n d a f t e r h e a v y rains,
decanting pickle
absorption
pond and
pro­
crystallisers,
by algal g r o w t h a n d t he d e v e l ­
- 126 -
opment of
red c o l o r e d b r i n e from h a l o p h i l i c bacteria,
dry storage
for pickle,
variations of
does
intake
vary b e t w e e n
Marrett
Research
Pond
Figure
Layout
It
able
son.
With a 2.5
and
that the pickle
of brine contained
d r a i n high
reasons,
Be b r i n e b a c k
i.e. , o n e
orated
again.
brine up to
to above
pond
25.6
1 metre depth
It
is g e n e r a l l y
toward the end
the bittern stage
evaporation factor
secondly,
de­
and re­
made is to
for two
is reduced in
the brine m ust b e
Be b e f o r e c r y s t a l l i s i n g
in
of the dry
into the concentrating area
and,
30
would need t o b e
One error that h a s b e e n
is that the
the concentrator system
plus an
crystalliser depth and
t h e c r y s t a l l i s e r area.
from crystallisers.
cap­
in t h e crystal-
pond containing
30 cm average
season to force as muc h
pond area be
from rainfall dur i n g t h e w e t s e a ­
sirable to lover crystalliser depths
moved
typical salinas
o f pickle normally stored,
meter dry pickle
of
for a
ty
Operation
in volume
season,
501
Ibis ratio can and
Based o n d a t a p t b l i s h e d
cm rainfall after decanting t h e pickle
area about
seasonal
Be rel a t e d t o area.
the volume
ior g a i n
a t end of dry
15:1.
etc.
3.7 w a s p r e p a r e d
plus t h e v o l u m e
allowance
from bittern,
seepage,
is r e c o m m e n d e d
of holding
lisers,
gravity,
7:1 a n d
labelled estimating
Pickle
salt recovery
use of
will t a k e
evap­
place
i
%
\
i
-127-
Withdrawal
bottom
well
(sump)
the bottom.
remain
is
M o d e s t a m o u n t s of
otherwise
through
by p u m p
The
of 24.5
- 25
pond
should b e
front a
to d r a w off the m ost saturated b rine
in t h e u p p e r strata.
removal
■
fran the pidcle
rainfall will be
slaw
to mix
and
Vhere el e v a t i o n s p ermit pickle
a gate operated culvert through
with suction as
low as
end concentrator pond
to assure
from
always h a v i n g
t h e dyke,
practical.
should
a 25.6
normally
- 26
have
a Be
Be t o feed
crystallisers.
As
low
Be b r i n e
previously
to such
reported provi s i o n
is needed t o add
facilities to prevent o r remove salt
tuild
up.
W here soil
conditions have
appreciable seepage
10~6 o r m o r e s h a l l o w pidcle ponds of 30 - 60 cm a r e r e ­
quired,
can be
mtil
deposited
In
given
with
algae seal
is o b t ained o r
o n t h e bottom.
laying out pidcle
to d i v i d i n g t h e a r e a i n t o
the
exits
arrangement
is
to have
dyke.
the
for t h e
same
ponds
This
consideration should be
two parallel
at t h e end opposite t h e
diagonal
a permanent salt cake
ponds, o b v i o u s l y
inlets.^
A suitable
a roughly rectangular area
allow
for p r o x i m i t y
of
divided
t h e two
by
a
inlets and
outlets.
-X
-128-
Tnere are a
parallel pickle
use one pickle
the
valuable
There a r e t i m e s
pond to be
saturated
to
allowed
An
nate years
to
while
important
for having
fill crystallisers w h i l e
saturate before using
additional
reasons
vihen i t i s n e c e s s a r y t o
alternate crystalliser is b e i n g filled
b r i n e and
the
ponds.
nunber of
with
unsaturated
in cry stallisers.
feature is that
o n e p i d d l e pjond i s b e i n g
in alter­
fed t o cry s tallisers
alternate c a n b e drained and depending o n condition of the
bottom
crop
or
if
can be h a r v e s t e d
it c a n b e
with
it h a s a
scarified
salt
floor b e low
even though
with
sea w a t e r o r w e a k
high
agricultural
the
in Ca
type
b r ine to dissolve
the brine to fill crystallisers.
so doing
the new
resultant pickle
Sea
is
low
on t he
reconstituted
content.
to drain off
the
factor can be
In
low
adapted by
Figure
voter
providing
result
in t h e
filled
and saturate
preferred as
by
in M g ++ w h i c h p r o d i c e s
output/ha.
the brine
a
3 -
3.3 t h e
prolonged
evaporation this
"pre-crystallisers"
p i c k l e t o f e e d c r y s t a l U s e r s.
would
Otherwise
De­
from t he salt
4 g/l
the
Mg++
difference
in the
seen.
locations having
fresh
salt
voter is
saturated brine will have
By u s i n g n o m o g r a m
evaporation
dity and
ability
SO4 .
t h e new
equipment,
a higher purity salt and hi^ier crystalliser
pending
crop
periods
of high
huni-
procedure can be
to p r o dice
Without d oing this
crystalliser that might
not be
low
Mg+ +
a thin cake
suitable
for
129
-
lew
cost mechanical harvesting.
reduce
Mgt+ a n d
Decant
System
CaS04
-
The
in the salt
additional
to decant rainfall
fran
the s u r f a c e o f b r i n e in c r y s t a l l i s e r s
This
is
pond
levels
change
is to
produced.
S o l a r salt operators attempt
impractical to d o
advantage
a nd p i c k l e ponds.
with weir boards at
from wind action,
rainfall,
gates because
and by
build-up
of salt on t h e boards.
A method of
successfully used as
after a rain
vhich
is
to 4.0
of decant b o x
by
two
ing
12.7
from
is
1M.
cm
1M
P\£
by
two
requires 6.9
float
A hock
is
the brine.
With a A
7.5 M 3 / m i n
used
from
of gate about
pipes or
lip of t h e decant
The opening
g a t e is
imbedded to prevent coll a p s i n g
above the brine
side
in t h e b r i n e
flexible rubber connectors hav­
wire internally
A 10
to
During or
The d i s c h a r g e t h r o u g h t h e
pipes using
structure.
on o t h e r
the
Figure 5.15.
the surface of
in u s e
t he gate or
in
s o t h a t a u t o n a t i c a l ly t h e
Rubber Compary).
when not
level
illustrated
cm below
S/S spiral
(Gates
floating decants was devised and
the decants are lowered
is d e s i g n e d
2.5
using
suspend t he decant
a timber
H of
3.75
from
to
45
extended
out
from
cm between b r i n e and
M ^ / m i n .is o b t a i n e d
two
gate
structures.
cm r a i n in 24 h o u r s o n a 10 h a c r y s t a l l i s e r
M3/min
removal.
An
attanpt
is m a d e
to place the
-130-
SECTION
LOm (TYP)
,|
SCH. 40 *PVC
1
:-V
;
• .•
i »-
y
.
— « I P ' I:u
j
___ - ___ J
f—
1
-----------------------------
i
k*M .1
j
•o
■rr n
l
\
L--. .
( =; !
BASIN
-
1
2.C7 em(TTP)
----------------------- ■
i
B
} l ____________
■
J
I...
— M il'll 1
1
(
l
ft
"*•1
r
----------------------
PLAN
I
1
FKJ 5 B FLOATMG DECANT TO REMOVE RAINWATER
'1 —
■I
■ • • ' ■: ’
A
-131-
decant
effluent back
essentially
wind
fresh
vater
direction and
needed.
density
ponds
into the pond
system
is decanted.
velocity
To design
and variations
Baume r e a d i n g s a r e t a k e n h o u r l y
approaches
a bank
after the initial
1 5 - 2 0 * Be
decants
of decants can b e
a decant system
during
storms
is
from decants a n d as
are
lifted.
provided through
For large
a
bulb head
wall.
Salt
Recovery
In
relative
From
localities having
humidity
be
in
additional
the max i m u m
accomplished.
Be
By u s e
calculated.
a
long dry
bittern discarded
ther concentrated
reaching
Bittern
In a
Figure
3.3 t h e
for example,
0.4,
land u t i l i z a t i o n w o u l d b e
( 3 2 Be) .
increased
b i t t e r n as
The
from 8 6%
increase salt
■ alt recovery.
recovery
to 95%
fur­
until
having
Be c a n
freshwater
and assume sat­
at an evaporation fact o r of
p o i n t of
from brine w o u l d t h e n b e
o r roughly 10%
discarding at
32
Be
3 0 Be.
operators
salt recovery.
would
salt
compared to
Some
76%
maximum
bittern can b e brought u p to near the salting
M g S 04
is
crystallising can be
t e n p e r a t u r e o f 20* C a n d r e l a t i v e h u m i d i t y 7 0 % ,
isfactory
low
to crystallise salt
effective
of nomogram
locality
from crystallisers
ponds
at w h ich
season and
d i s c a r d b i t t e r n at
In t h i s c a s e
reocovery
Wien the
29
Be w h i c h
is a
a bittern salt recovery system
from
76%
t o 95%
maximum desired
or a
25%
greater
Be is r e a c h e d b i t t e r n
-132-
is dra i n e d
than
from
such
dissolved using
the
systen.
The
time used about
o u t p u t of
service
years.
of
and
Pond
program.
mat
for s e a l i n g p u r p o s e s
This
documented
a
to perform
if percolation
J o n e s et
reduce
rate by
a
monitor­
development of
an algal
is
Inter­
a problem.
in Figure
degrees
amounts
of fertilizer
the growth
of
thusly reduced
trometer.
soils and
tom .
that have
factor of
algae.
(0.7 p p m )
The
from 96%
Colloidal
been corrected by
a
to
as
particals
two
ribbery
measured
plugs
10.
problems of
adding trace
light transnission
to 55-70%
algal
also deposits
for o n e
5.16,
A one m m depo­
New salinas historically have seepage
varying
part
a biological
<al. w e r e p l o t t e d
the percolation
recent
regular employee or by
service can maximize
of d a t a of
in
that the services
demonstrated h o w a l g a e deposits r e d u c e seepage.
can
a total
for h y d r o b i o l o g i c a l t e c h n i ­
It is r e c c m m e n d e d
outside technical persons
ing
sit
of
Sealing
salina has been well
See b i b l i o g r a p h y .
pretation
out
t o n s p e r year.
a m a r i n e b i o l o g i s t e i t h e r as
time
in C a l i f o r n i a a t o n e
for b i t t e r n s a l t r e c o v e r y
Salinas
to a
is s c a r i f i e d ,
water and returned to
operations
The technology a n d n e e d
cal
t h e salt
weak b r i n e o r sea
100 h a
of
ponds,
L e s l i e Salt
500,000
Hydrobiology
pond or
years
to enhance
of pond b r i n e
by
voids
is
a light spec­
in sa n t y
like blanket on the
silty
pond b o t ­
-133-
( 1 ) ORIGINAL MATERIAL PERCOLATION
(2 ) ORIGINAL MATERIAL PLUS ALGAL MAT
«(2)
PERMEABILITY RANGE OF MATERIAL
(I)
A
B
C
D
E
SOIL& SHELL
ARAYA RED SOIL
ARAYA CALICHI
ARAYA CLAY
PLASTIC a AY
(SOURCE: JONES * ol )
Figure 5.16
REDUCTION IN PEROOLATION BY DEPOSITING ALGAL MATERIAL
-134-
This technical
the
microorganism
a n c e to avoid
sity
brine
population to some reasonable degree of b a l ­
or minimize
of brine)
service can establish and control
development of mucliage
in t h e saline.
The result o f h i g h
is r e d u c e d e v a p o r a t i o n rates,
fine salt and
lower quality.
d u c t i o n of h a l o f i l i c b a c t e r i a
scale
costly
only
to
find
(red c o l o r of brine)
dye
to
maximun
to brine
program
dye
should be
o f t h e saline in question.
gathered
of pond brine in areas of
nitrogen
production
et
al.) .
tailored to the
Data should be
low,
intermediate
to include:
1.
Total
2.
Identification and estimation
n i t r o g e n a n d p h o s p h o r u s c o n t e n t o.
of the
sources o f
and p h o s p h o r u s contributors.
3.
transmission
Oxygen,
salinity,
Ph and percent
of
licfit
of brine.
4.
organic
ponds
in crystallisers
(Jones
particular needs
and high salinity
evaporation.
from halofilic bacteria grown
n a t u r a l l y is a l m o s t a s e f f e c t i v e a s
monthly
pro­
in final
maximize crystalliser
that the red color
The monitoring
viscosity
It h a s b e e n e s t a b l i s h e d t h a t
addition of
has been used commercially to
visco­
increased production of
ponds and crystallisers contributes
Large
(high
Identification of
dissolved
and particulate
natter in brine.
5.
Depth and
identification of b o t t o m deposits.
6.
Gt>lor o f b r i n e .
-135-
7.
Correlation of
The
minimum basic
1.
A high
w i t h 10X, 4 0 X ,
data with salina operation.
equipment neede
is:
quality conpound binocular microscope
a n d 100X objectives,
equipped
with a n
integral
photographic camera.
2.
Light spectometer to measure turbidity of
3.
Centrifuge
4.
Burettes,
5.
V a c u u m punp
brine.
6.
Low
7.
BOD bottles,
reagents.
t e m p e r a t u r e d r y i n g oven.
Portable oxygen
metre
for u s e
in salina o r
lab­
oratory.
Figure
living organisms
in
5.17
plots
the total
a salina having
p o p u l a t i o n at v a r i o u s
salinity
In r a n y s a l i n a s t h e
of
balance causing
kinds
and a m o u n t s of
a balanced
of brine
microorganism
(Davis).
microorganism
an accumulation of highly
population is
viscous by
out
prodict
of coccochloris a nd organic suspension that seriously supresses
evaporation.
tion
time
sity
brine
to
L
By
operating crystallisers
of b r ine
in s e r i e s t h e r e t e n ­
is rediced an d consequently t h e h i g h
is p u r g e d .
At
operate crystallisers
visco­
one salina the operating practice was
in parallel and
X
discard b i t t e r n at
27
S A L IN IT Y
F iq u re
IN B t
5.17
TOTAL BIOMASS VS. SALINITY FOR PROPERLY FUNCTIONING SAUN A
(SOURCE * OAVIS)
-137Be1
* because of high
salt
from b rine
adopted
and
was onl y 50%
to r e d u c e
shrinp).
another
brine
The
did not
Project
period
small
resultant recovery
3.6).
nutrients
A program
population
ountry
These a r e
artimia
typically
(brine
was in bal a n c e a t
and this problem
of
viscous
PROJECT
COST,
PRODUCTION COST AND
PROFITABILITY;
Cost:
of
the
construction of
two t o three
project area
buildings
equipment are
sories
was
exist.
the
salt
is possible.
and civil w o rks
purchased.
is c l a s s i f i e d
a r e erected,
under
The
capital
Earthwork
ii)
Buildings
and
iii)
Plant and
equipment
v)
of the
During t h i s p e r ­
Simultane­
machinezy
and
Miscellaneous a c c e s ­
investment in t h e proj­
five heads:
i)
iv)
is s p r e a d o v e r a
is progressively developed.
procured and installed.
are also
works
years d e p e n d i n g u p o n t h e length
season w h e n development work
ously,
of
(from b i r d droppings)
shell p o p u l a t i o n and
in t h e same
The
ect
(Figure
the input of
microorganism
salina
ESTIMATION OF
iod,
The
to increase the consumers of organics.
c e r t a i n grasses,
dry
viscosity brine.
civil works
Miscellaneousaccessories
Preliminary and
pre-operative
expenses
-138-
Details
of
capital
i n v e s t m e n t u n d e 1* e a c h h e a d a r e
discussed belov:
(i)
Earthwork
This
classified
Earthwork
item
covers
all
land development operations
u n d e r t h r e e si4> h e a d s :
a)
Concentrating a rea earthwork
b)
Crystalliser area earthwork
c)
Miscellaneous earthvork a n d roads
in t h e c o n c e n t r a t i n g
area consists principally
boundary
enbankments,
drains.
Embankment construction consists of
tion
of earth
tances
2
with lead and
over which
metres,
consists
of
vision has
sub
ping
of
in the
the
of
roads
works,
rates
for additional
and
crystalliser ponds
lead
and m i s c e l l a n e o u s
is c o n f u t e d .
lift and
dis­
50 metr e s a nd
Here,
cost keeping
in t r a n s p o r t i n g t h e earth.
the volume
in the area
within
forma­
vertical
inqport n e t e r i a l .
earthwork,
gen­
pro­
in view
Under the
gravel t o p ­
enbankments, a n d transport roads
crystalliser area are provided.
salt
lead
levelling of
some roads, b o u n d a r y
specifications
ing
conveyed)
cut a n d fill a n d
distances involved
of
is
water
cutting and
(horiaontal a n d
of
Earthwork in the crystalliser area
formation and
to be made
heading
enbankments and storm
lift
the earth
respectively.
erally involving
longer
internal
and
of earthwork
The
Based on the design
with lead an d
unit cost
for e a r t h w o r k
of
lift
is b a s e d o n p r e v a i l ­
under different conditions
for d i f f e r e n t t y p e s of
soils.
1
-139-
(ii)
Buildings
A
typical
list of buildings
for a
salt w o r k s would
be:
a)
Site office
and
laboratory
b)
I n t a k e b r i n e p u n p i n g s t a t i o n A > o r e % e l 1 ptnnp
houses
c)
relift punping
d)
workshop and stores shed
e)
workers
Space e s t M a t e s
ments
of
the
cost
rest shed
buildings a r e b ased u p o n t h e requ i r e ­
salt w o r k s w h e n
struction costs
cenent
for t h e
station
it r e a c h e s
for s t a n d a r d h e i g h t
concrete or
asbestos
of naterials and
cement
full
buildings
local
wage rates.
for th e
following
structures:
a)
S l u i c e gates,
b r i n e transfer weirs,
culverts a n d
Plant
pipes,
syphons
b)
Sumps for punping
c)
Ftesh
stations
water s u m p and overhead t a n k s a nd d i s ­
tribution
(iii)
Con­
with reinforced
sheet roofs depend o n
Provision should also be made
civil
prodiction.
lines
in the o f f i c e a r e a
and equipnent
The
a)
following
itans
are provided
I n t a k e b r i n e puitps c o u p l e d
diesel drives
under t h i s head:
with motors o r
-140-
to)
Suction and delivery
piping and sluice
valves
c)
Relift punps
of
intake b r i n e p u nps
smaller c a p a c i t y c o u p l e d
engines,
d)
similar to
to motors or
piping and valves
Vacuum priming punps
for i n t a k e b r i n e a n d
relift punps where required
e)
Electrification equipment and distribution
lines
(iv)
f)
Vfeshery e q u i p m e n t
g)
Crushing mill
h)
Mditive
and drier
mixing and packaging
equipment
Miscellaneous Accessories
Details
of
investment
under
this head a r e g i v e n
below:
a)
Vehicles
b)
Furniture
c)
Laboratory
Laboratory tables,
chenicals,
ance,
drainage
charts,
fittings,
vater
laboratory
d)
and bench
cupboards,
furnace and hot
sieving
distilled
miscellaneous
grinder
vooden racks a n d
muffle,
vacuum pump,
supply,
and
ovens,
equipment and accessories
plates,
machine an d sieves,
flame
photometer,
plant,
Vbrkshop equipment
welding
electric bal­
sink and
vater
reference bock s
soil testing
equipment and
grinder,
glassware and
equipment,
fittings.
- Lathe,
set,
tools
flexible shaft
set and access-
-141-
sories,
electrical
s h o p racks,
elsewhere
drilling machine,
miscellaneous
work­
equipment not
specified.
Garage
storage tank an d
equipment - Hashing
metering pump,
punp c o n n e ctions and
miscellaneous and
level,
equipment,
chain pulley blocks,
e)
gauge,
testing
oil
storage
diesel oil
pressure
tanks,
s u n d r y items.
Tractors
g)
Survey a n d
and
trailers
meteorological
levelling staffs and
Stevenson's
screen,
r a i n gauge,
evaperimeter,
h)
coiqpressor a n d a i r
fittings,
f)
compass,
ramp,
theodolite,
thermohygrograph,
Staff
canteen and accessories,
rainfall
hydrometers,
amenities
toilet
-
equipment
facilities
Dunpy
double
recorder and
miscellaneous
Hresh
-
fittings.
water trailers,
for s taff a n d
workers.
(v)
Preliminary
and pre-operative
Under this head the
expenses
following items are normally
included:
a)
Registration and
b)
Financial i n stitutions inspection charges
c)
Mortgage
d)
L e g a 1 cha r g e s
e)
Salaries and administrative
charges,
conpany
formation expenses
if any
charges during
construction
f)
I
Travel and conveyance during construction
-142-
P r o & i c t i o n cost:
The
of
production
itens
of
expenditure that constitute the cost
of salt can b e broadly grouped
under the
follow­
ing heads:
I.
FIXED EXPENSES:
Staff salaries
General
administrative
expenses
Rent,
rates,
and taxes
teintenance and service
expenses
Earthwork repairs
II.
VARIABLE
EXPENSES :
Brine punping a n d distribution
Harvesting
and handling
hashing and storage
Packing
and
During t h e construction period,
incurred
on
supervision,
forwarding
all
expenditure
general administration and conveyance
is allo c a t e d t o c a p i t a l a c c o u n t u n d e r p r e l i m i n a r y a n d
tive
expenses.
under
production
On c e prodiction commences,
expenses
for another y e a r or two
works
are
given below:
may continue
full rated capacity of
may b e reached after three o r
Details
these are covered
even t h o u g h construction
and th e
preopera­
t h e salt
four years.
of expenditure under each head of
account
-143-
(i)
Staff salaries - This item
t e s
for a
small b a t c h
shift operators.
sized salt
(ii)
works
General
phone,
presented in
the operation of
Rents,
The
within
policy
tures
The lands
produced
plant and
is
of all
It
the assets.
and
leased
maintenance,
The
- This
years.
item
equipment,
general
p a r t s replacanent,
naintenance required
to ensure
to be
provides for
civil struc­
in which the
extremely corrosive,
is e s s e n t i a l
a royalty
leases are granted
as long as 99
includes cost of
Buildings n e e d
the coun­
of area leased and
plant a n d
is
to most solar
to country and
Since the environment
operate
painting
equipment.
office
tele­
from p r o v i n c e t o province.
levied.
painting and other
equipment
maintenance
in connec­
postage,
from country
varies
which could b e
foundations.
of
to median
includes all
to t h e g o v e r n m e n t o f
varies
thenselves,
naintenance
for upkeep
of the
belong
of rental
salt
lubrication,
small
like
insurance,
Maintenance and service expenses
and
a
and conveyance expenses.
varying periods
routine
for
staff and
Figure 5.18.
a ground rent per hectare
p er tonne of
(iv)
chart
salt works
rates and taxes -
countries
Normally
the
printing,
projects generally
try.
for
organisation
stationery and
(iii)
of supervisory and technical
a general and fixed nature incurred
staff travelling
salt
is
salaries and prerequisi­
administration expenses - This head
expenditure of
tion with
An
covers
the
periodic
longevity
frequently white
washed
F ig u re
5.18
O RG A N ISA TIO N
WORKS.
CHART
FOR S M A L L
TO
M ED IU M
S IZE D SALT
-145-
si nee e ven
addition,
by
cement p l a s t e r is s u b j e c t
painting has
an anti-corrosive
nance cost per
to be done
epoxy
to
with
paint.
saline corrosion.
a good
Plant
year could b e as h i g h as
primer
In
followed
and equipment m a i n t e ­
8
- 10%
of the
value o f
t h e equipment.
(v)
Earthwork
repairs
channels and roads
t h e rains,
of the
soil
sion and
is high.
formation of
to be
p o t holes.
The
year.
(vi)
tric
Brine
All e a r t h
to
usually
and sand content
Gravel topped
par e v e n t t h e
formation o f
carried out round t he
expenditure
and
could
lubricants
the b r ine intake
vary
is
made based on
f r o m 5%
to
10%
of
- The
composition of
elec­
for o p e r a t i n g m o t o r s a n d
and
relift punps
is c o v ered
o f account.
Harvesting
and handling
- The
maintenance a n d conpaction,
covered
sides.
pimping and distribution
road
silt
year after
of th e earthwork.
to drive
the nearest
the
for t h i s i t e m o f
site conditions
under this h e a d
(vii)
is
the
every
embarkments,
embankments are sibject to e r o ­
ruts along
power/diesel o i l and
engines
liser
in a r e a s w h e r e
repari work
the capital cost
comprising of
maintenance
frequently checked
Provision
the prevailing
fields
will require
especially
roads have
- Salt
and transport to
under t his head.
cost
salt
of
annual crystal-
extraction,
transfer to
the washery/stadeyard is
-146-
(viii)
ery,
Washing
and storage
washing losses,
- The cost of operating the wash-
storage and h e a p covering
expenses fall
u n d e r this head.
I lx)
Packing
crushing and
loading
and
forwarding - U n d e r this head
additive
mixing
(where applicable),
trucks/railwagons/ships
c h a r g e d o n t h e assets.
packing and
is provided.
In addition to the a b ove
normally
the cost cf
expenses,
The
depreciation is
following depreciation
rates a r e typical:
Earthwork
40
years
Buildings and civilvorks
25
years
Plant equipnent and punps
15 y e a r s
Portable
equipment, haulage,
harvest,
5 years
etc.
P r o f x t a b i l i ty:
Based
of the
on
the prevailing market
product that c a n b e realised
This
is d o n e b y
lies
within w h ich t h e salt produced
the
landed
cost
determining the
a
schedule
mally
made
at
ex-factory
the value
is estinated.
'e c o n o m i c m a r k e t i n g
z one'
that
is conpetitive in terms o f
in t h e market.
Based
dule,
factors,
on the ex-factory
of revenues can b e
price and p r o d u c t i o n sche­
w o r k e d out.
constant price without providing
so t h a t t h e e s t i r a t i o n
of the p rofitability is
lhese are n o r ­
for escalation
in real terms,
-147-
i.e.,
after adjusting
of any differential
assunption,
for the effect
of
inflation.
changes in price indices
since the profitability worked
t h a n t h e est irate b a s e d o n
is
flie a b s e n s e
a conservative
out would b e
lower
a progressive rise in revenues and
costs.
Based
on the year-wise
expenditure t he gross
depreciation,
cable
flew
may b e
discounted cash
a DCF rate of
inflows and
consideration of
After deducting
flow c a n b e
worked
out.
In
taxes/incentives appli­
t h e time
flow
(DCF)
project.
method is used to
This i n v o l v e s the
return at which
outflows are
value
of
the present values
equated.
money
Due t o the
DCF returns are gen­
lower t h a n t h e conventional r e t u r n o n in v e s t m e n t of
projects with
of
out.
revenue and
tax pay a b l e t o government,
special
profitability of the
of net annual
vary
cf
incorporated.
calculation of
erally
operating c a s h
c a l c u l a t i o n any
The
assess the
worked
th e p r o f i t b e f o r e tax,
profit after tax and
the cash
profit is
schedule
a
long gestation period.
from country
DCF return expected may
t o coixitry d e p e n d i n g o n t h e
opportunity cost
investment.
The
establish the
following
viability of
financial
data
a project:
1)
Capital outlay
2)
Share capital
are then worked o ut to
-148-
3)
Maximum
long term
45
Maximum debt
5)
Repayment period
6)
DCF r ate
equity ratio
development
of
raw
developing
material
addition,
u s e of
viability of the
of
long
project,
a basic incbstry
use and
skills.
a y a r d stick
in t h e l a r g e r c o n t e x t
for t h e pr o d u c t i o n
for
for
i n several c a s e s the
the project must be viewed
of daily
term debt
DCF method as
this incbstry provides
local
for
of return
In a d d i t i o n t o t h e
measuring the
debt
industrial
of
a vital
application.
In
employment and encourages the
-
149 -
C H A P T E R - VI
MODERNISATION AND
The
bale
it u s i n g
formed is
without
solar heat
scooped
in shallow
out using shovels
further processing.
a
low
quality
as
product
out.
edible
its
by
suitable
this method
some
ble
salt h a s b e e n to
or
The
scraping
salt
salt
evap­
t h a t is
planks a n d
sold
method of production and
salts other t h a n NaCl
or as preservative
prescribed
chemical
for
in villages.
It
for t a b l e s a l t a n d
industry
on account of
The s i z e o f t h e f a rms tha t c a n b e controlled
is a
support neither
Today
INDUSTRY
This c r u d e s a l t is suitable o n l y
f o r u s e in any
inpurities.
pans.
since the
cannot achieve the specifications
is not
making
SALT
This has been the method practiced
It i s a n i n e f f i c i e n t
are not separated
consumption
SOLAR
from creeks or backwaters into a pond and
for centuries.
yields
THE
traditional method of
out b r i n e
orate
MECHANISATION OF
few h e c t a r e s a n d
a modern chemical
a number of
countries
extent p u r e l y
to meet
such
small s i z e d farms
can
industry or an export trade.
follow
the traditional method to
limited local requirements
for edi­
purposes.
With
the aduencement of
science and technolo$r,
several refinements h a v e be e n developed in order to produce
a
-150-
high
purity
hand
with
salt
Above
Modernisation c a n go hand in
employed u p to
t h a t level,
more economical.
countries depending
For
cost.
nanual labour being
o f production.
becomes
at minimum
a particular level
mechanisation of
This l e v e l
is different
upon the prevailing wage
operations
for different
a n d p r i c e levels.
a developing country there l a bour is cheap,
this
l e vel is
in t h e r e g i o n o f 4 0 , 0 0 0 tonnes p e r annum.
Modernisation is ap p l i c a b l e in
operation of
a
ing
c o n c e n t r a t i n g ponds,
systems,
storage
and
transport.
these aspects
Layout:
salt w o r k s viz.,
layout,
stages of
is n o w recovnted
(see
maximise production.
optimum pond depths
of
layout area a r e now
№thenatical
models and
for s o l a r p o n d systuns
maintained at different
concentration and prescribe procedures
for brine
at different times
electrically
To control tidal intakd o f brine,
o p e r a t e d tidal g a t e s a r e b e i n g used.
t i d e t h e b r i n e p u i ^ s a r e a u t o m a t i c a l ly s w i t c h e d o n
— w
of the
o n p r e v a i l i n g w e a t h e r c o n d i t i o n s a n d o t h e r inputs.
Brine intake systems:
a
punp­
Figure 6.1).
to be
transfer and concentration control
year based
o f brine,
crystallisers, harvesting,
computer programmes have been developed
to specify
intake
The salient developments in each of
Scientific design methods
available to
every phase o f
continuous
inflow
into reservoirs.
Where tidal
During low
to maintain
inflow
is
m
FIG. 6.1/. SEAWATER
INTAKE SYSTEM
USING
FLEXIBLE
PIPES-
-152-
inadequate,
sea
using
the
sea bed
salt
flexible h i g h density
and
brine close
sand
works are resorting
connected
to the surface
(Figure 6.1).
undiluted sea
priming
used
to
and
This
water.
consune
advantage
very
in using
in the
diesel
used
a concrete
of the
system
little
sea
intake
to
open,
power
as shown
as prime
plastic materials
(HOPE)
poly
and
vinyl
fibreglass
non-corrosive and
block
to draw
minimise intake
ensures
these axial
movers,
preferred since t hey a r e cooled
These are
front t h e
of
continuous drawal of
Large turbine type punps that require n o
can be erected
engines
pimping
polyethylene pipes resting on
are being
for i n t a k e b r i n e a n d r e l i f t p u n p i n g
added
New
to direct
is
that they
F i g u r e 6.3.
Among
marine type engines are
the o l d e r m e t a l l i c piping.
( P VC), h i g h d e n s i t y
reinforced plastics
often less
punps
An
by t h e i n t a k e b r i n e itself.
are replacing
chloride
(Figure 6.2).
flow
in
increasingly
(FFP).
polyethylene
These are
expensive than cast iron or steel
pipes.
Concentrating
depth
ponds:
It
is now
in the concentrating
ponds fairly h i g h
p e r m a n e n t b u f f e r o f b r i n e is
Several salt
works in
concentrating
pond
breakage
as
shewn
to receive only
well
so that
a
c reated w i t h i n t h e salt works.
advanced countries
pond depth of
embankments are
the practice to maintain the
neintain reservoir and
2 t o 3 metres.
protected
in F i g u r e 6.4.
direct rainfall
The concentrating
with boulders
Thus a
to prevent
salt w o r k s is d e s igned
tfiich cart b e
allowed to
V
r
r
y
-15 3-
Fig. 6.3
Large capacity pumping station with overhead crane
*
Fig.
6.4
Internal embankments lined with boulders
É
Fig. 6.5
Large crystallisers with series feeding
arrangement
-155-
overflow.
and
The
increased
that
salinity within the
year after
a r e two
hectares
each
are
still
as
inpervious as
charge
itate
strength and
possible.
the crystallisers deep
reaches
fresh brine.
the brine
29*
Be
fully.
like n a p h t h o l g r e e n B
and
increases pr o d u c t i o n by
our
of
15 -
salt
it.
This
10
t o 15
Harvesting
equipnent
is
formed
to ensure
practice
to
facil­
Wien the concen­
two o r t h r e e t imes b e f o r e
the brine w i t h chemi­
absorption
20%.
improves evaporation
ems
is p r o p ­
e m s ) so as t o
Also
algae halophilic bacteria in t he brine
to
soil
is r e p l e n i s h e d w i t h
Colouring
dye h e l p s
large size of
crystalliser beds
o f salt.
The p rocess is r e p e a t e d
is d i s c h a r g e d
the
20 - 4 0
the crystalliser
cals
tain
(say
of
The
also cannon
ininterrupted crystallisation
tration
made
when required
to make
It i s
vorks brines
storage.
in F i g u r e 6. 5 ) .
erly conpacted and treated ch«ideally
sufficient bearing
in
Crystallisers a r e n o w
(as shown
is thus preserved
In s e v eral s a l t
to t h ree years old
Crystalliser area:
many
year.
salt works
of radiation
the growth of
inparts
rate.
Thus
for h a r vesting
is a v a i l a b l e i n d i f f e r e n t
a
cer­
a pink col­
thick
layer
mechanically.
shapes and
sizes.
They c a n b e independently driven,
pushed o r pulled,
mounted
on
wheels
Most
off
salt
tracks,
of the m
the
rollers,
operate on
caterpillars,
a canmon
c r y s t a l l i s e r p o n d by
principle
floats.
of-scooping the salt
inserting a blade
layer a n d transporting it t h r o u g h
or
underneath the
a d r a g c o n v e y s r/t r u c k
-156-
m o vi ng
alongside
liser.
Figures
Where the
the harvesting machine inside the crystal6.6 a n d
c r y s t alliser beds
inside the
pond
F i g u r e 6.8.
the
to
six w e e k s
at
work
and ground
thickness
plying of
vehicles
salt
to the nearest
road as
shown
in
The harvesting operations a r e restricted t o about
nachines
mate
do not permit
of harvesters.
a series of portable belt convenors a r e used to
transfer the harvested
four
6.7 s h o w d i f f e r e n t t y p e s
the end of
for nearly 14
the
- 16
conditions permit a
of one or more
the most preferred
season during which
hours per
permanent
years h a r v e s t
form of harvesting
is
day.
salt
time
ttiere c l i ­
floor of
naintained.
since the salt
a
This is
floor pro­
vides the n e cessary ground bearing capacity t o support heavy
harvesting
tion
e q u i p n e n t a n d t h e r e is
of t he s a l t
w ith c l a y o r sand.
rainfall
is high,
In
ponds
with h i g h
by
lining
the
little chance of
maintenance of
a
seepage rates,
f loors w i t h low
However,
salt
contamina­
in areas
floor is
Where
n o t possible.
percolation is b e i n g arrested
density polyethylene
(LDPE)
s h e e t s.
Salt
washing:
trucks
to the
subjected
works
removes
thorough
(Figure
and
dunped i n t o
6.101.
Hydrocyclones are
The
of t h e insolvble
salts
is t r a n s p o r t e d b y
a b out 50 -
thorough
and screw
a'lso u s e d
in
some
scrubbing w i t h brine
inpurities,
70%
trailers or
a pit and
agitation in agitators
( F i g u r e 6.9).
most
magnesiun
tashery there it is
to a
classifiers
salt
Hie harvested salt
a good
of the calciun
portion of the
salts.
Tbday
Fig
Fig
6.6
6.7
1000 t onnes/hour salt h a r v e s t e r w o r k i i n g on salt
floor with truck transfer
200 tonnes/hour salt harvester on clay floor
with truck transfer
Fig
6.8
Fig. 6.9
200 tonnes/hour salt ha r v e s t e r on clay floor with
conveyor belt transfer
Mechanical salt washery with screw classifier
and woven wire belt
-159-
Fig. 6.10 Mechanical salt washery with dewatering screen
and centrifuges
Fig. 6.11 Linear stacking of salt
TT
—f —
•m
-160-
s o l a r salt
works
99.7%
with calcium and
NaCl
are able to supply
sulphate content below
Storage
of
salt:
The traditional practice of
is n o w b e i n g re p l a c e d
large
heaps.
The
exposed
the
is
loss
heaps
rainfall
used
per
reduced
(Figures 6.11
when
the s maller is
salt
is
As
is
a result,
stored
The
in
of more
subjected to a
Both linear a n d r a d i a l
a n d 6.12).
of salt in
metres in quantities
even when the heap
o f 1 2 0 G mm.
the heap,
to rainfall.
l e s s t h a n 8%,
in excess of 8
tonnes,
of
unit quantity
to
covering salt
by mechanised s t a c k i n g
larger the size
with hei g h t
than 5000
magnesium contents b e l o w 0.05% an d
0.1%.
heaps
the area
salt h a v i n g a p u r i t y o f
total
stack yards are
stacking belt conveyors move
o n rails.
Destacking:
vAieel
Stored salt over a p e riod of
excavator
mechanically
type destackers h ave
remove
Refining of salt:
is diss o l v e d
all
inpurities.
effect
powder.
and
vacuum
The
cooled
grain.
ing
in
t h e salt
fresh water.
made
The
high
salt
in
crystallises as
flowing a f t e r t r e a t m e n t
A
remove
multiple
a
fine
in r o t a r y kilns
purity product of
agents.
A
evaporated
is t hen filtered a n d d r i e d
free
to
solar salt
T h e b r i n e is p u r i f i e d t o
pan evaporators.
a very
Bucket
now been developed
works t h e c r u d e
The b r i n e is t h e n
to achieve
It is
hardens.
from t h e heaps.
In c e r t a i n s a l t
slurry
time
uniform
with anti-cak-
Fig. 6.12 Radial salt stacker
*
Pig. 6.13 Jetty for direct loading of salt into ships
-162-
However,
alternative salt
in view
refining
recrystallisation have
stage
washing and
fluid
bed
Varieties
of
rising
methods that d o not
be e n developed.
scrvbbing process
drying
the
salt
applications.
a high degree of
mineralised salt
softener
salt,
deficiency
Transport:
A major
in
the physical
vary to suit
salt,
fortify salt
are
et c .
different
i o d i s e d salt,
compressed
trace
water
A process has been
with iron to reduce iron
large
salt
s o m e a r e a 8.
rate of
as
recent
solar salt
develop­
loading achieved by
in
bulk
t h e s e salt
30,000 tonnes per day h a s h e l p e d t h e m c a p ­
Japanese and
In a d d i t i o n
all
to direct ship loading facilities
The high
ruining u p to
m i s sion of
in a l l cases,
salt blocks,
feature of
is t h e i r a c c e s s
ture the
salt.
to
Wiile t h e chemical c o m p o ­
the varieties
enriched dough
several varieties
anemia.
( F i g u r e 6.13) .
works
of
for cattle,
recently developed
ments
in producing
additives used
Some
a multi­
In t h e advanced cointies
is t h e same
properties and the
involve
screening.
for d i f f e r e n t applica t i o n s .
sition of
These
by centrifuging,
sophistication h a s been achieved
of salt
involve
followed
and
of salt:
fuel c o s t s several
South Korean markets
to t he normal
a
slurry
methods
through
for industrial
of transport,
pipelines
trans­
is b e i n g a d o p t e d
Artificial
humidity,
of
solar
methods:
sandy
salt
High
cost of
land,
low
soil a r e inhibiting factors
and the Japanese have
to overcome these handicaps.
effect
vacuum
method
initial concentration is effected
dewn
a
evaporates to
series of
in the
developed
niques
flew
temperature,
special tech­
c o n c e n t r a t e brine.
slopes resulting
making th e seawater
in partial
is collected,
where
elongated bamboo poles which
evaporation.
brine
is
obtained
removed
fed
down
in the
and
the
form of
salt
high
degree
and
salt
ical
slurry
of sea
is
centrifuged
from
from which
A recently
from
causes further
is reached,
Salt
the
is
inpurities a r e then
developed technique
voter in chambers partitioned
arranged.
fed t o e vaporating
and
Salt c o m e s
t h e n dried.
fields a n d replaced them
making
a height
By
by
this process a
o f initial concentration is achieved a n d t h e con­
external heating.
is
a
membranes alternately
centrated b rine
with
evaporation.
conpression evaporators.
is dried.
is t h e e l e c t r o d i a l y s i s
ion exchange
punped up to
then the required concentration
into thermo
multiple
In a n o t h e r
The resultant b r i n e
it d r i p s
manufacture
One method uses
by
high
an
indistry.
agricultural
by
type
crystallisers provided
out in the
form of
a
slurry
This process h a s eliminated
factories and converted salt
of operation to a
R e s e a r c h is a l s o b e i n g c o n d u c t e d
desalination processes and recover
salt
to
purely
chem­
inproving
as a byproduct.
-164-
Bittern
salts:
tftiere s a l t
production
is
of bittern
recovered
this
On
a
medium
bitterns
are of
of the order of 50,000
is
level t h e bitterns
and magnesian
fields
and
scale,
is n o w
inadequate
tonnes or
for any
form t h e b a s i s
sometimes of
size
a
and the
less,
the
f u r t h e r use.
for r e c o v e r y
potash on
production of t h e
commercially
median
amount
Above
of bromine
commercial
following salts
scale.
from
feasible:
Magnesium sulphate
M a g n e s i a n chloride, m a g n e s i a n
magnesian tri silicate
hydroxide
and
Bromine and bromo compounds
Plaster of
Paris
(from gypsun)
Research is b eing c onducted o n t h e
other compounds
sea
water.
on a
The solar salt indistry
development of
try.
including uraniun
a b a sic chemical
The proper
therefore assunes
commercial
forms t h e
industry
planning and development
crucial
importance.
production of
in a
scale from
nucleus
for t h e
developing coun­
of this
indistry
- 165 --
APPENDIX I
BIBLIOGRAPHY
APPENDIX II
SOURCES OP INFORMATION ON THE
SOLAR SALT INDUSTRY
APPENDIX III
CONFERENCES ON SOLAR SALT AND
ALLIED TOPICS
- 166 -
APPENDIX
CHAPTER
Is
IMPORTANCE
OF
I -
BIBLIOGRAPHY
SALT
1.
Kaufinann, D . W . , 'S o d i o n C h l o r i d e ' , A C S M o n o g r a p h
145, R s i n h o l d P u b l i s h i n g Q>rp. , N e w Y o r k , 1960.
2.
K o s t i d c , D e n n i s S. , ' S a l t ' , M i n e r a l s F a c t s a n d
Problems, 1980 Edition, Bulletin 671, Bureau o f
Mines, U n i t e d S t a t e s D e p a r t m e n t o f t h e Interior,
W a s h i n g t o n , D.C. , 1 9 8 1 .
3.
W o o d , F.O. , ' S a l t & s a l t p r o d u c t i o n ' . T h e N e w E n c y ­
c l o p a e d i a Britannica, tocropaedia, 1 5 t h Edition,
V o l . 16, p p 1 9 2 - 1 9 5 , E n c y c l o p a e d i a B r i t a n n i c a I n c . ,
(hie a g o , 1 9 7 9 .
4.
'A H i s t o r y o f S a l t ' ,
I l l i n o i s , 1951.
5.
W i l k i n s o n , W i l l i a n B-, ' R o m a n c e s a n d
S a l t ’, Ithaca, N e w Y o r k , 1969.
6 .
Young, Gordon,
'Salt:
T h e e s s e n c e o f Life' ,
tfetional G e o g r a p h i c M a g a z i n e , V o l . 1 5 2 , N o . 3,
National Geographic Society, Washington, D.C.,
1977.
7.
’S a l t : A N e w V i l l a n ? ' ,
M i r c h 15, 1 9 8 2 .
8.
'Salt i n y o u r die t ' , S a l t R e s e a r c h & I n d u s t r y , Vol.
4, N o . 4, O c t o b e r 1 9 6 7 , C b n t r a l S a l t L Ftorine C h e m icals R e s e a r c h I n stitute, India.
CHAPTER
II:
STATUS OF
THE
SOLAR
M o r t o n Salt Coiqpaiy, Chicago,
Time,
SALT
'Handbook
N e w York,
Vol.
119,
INDUSTRY
of World
1969.
Notes on
No.
11,
IN T H E W O R L D
1.
Lefond, S.D.,
Ple n u n Press,
Salt
Resources',
2.
United Nations Industrial Dev e l o p m e n t Organisation,
V i e n n a , ' M o d e r n i s a t i o n a n d t e c h a n i s a t i o n o f Salt
Industries based o n sea water in developing coun­
t r i e s ' , P r o c e e d i n g s o f E x p e r t G r o u p M s e t i n g , Rome,
p p 2 5-29, S e p t o n b e r 1 9 6 8 .
3.
'The
kill
4.
K o s t i c k , D. S. , ' S a l t ' , P r e p r i n t f r o m t h e 1 9 8 0 B u r ­
eau of M i n e s & M i n e r a l s Y e a r Book, U n i t e d S t a t e s
D e p a r t m e n t o f t h e Interior, 1981.
E c o n o m i c s o f Salt', Third E d i t i o n 1979,
I nformation S e r v i c e s Limited, London.
Ros-
- 167 -
CHAPTER
111:
CHEMISTRY OF SOLAP
SALT MANUFACTURE
1.
R i l e y , J . P . & S o r r o w , G. , ' C h e m i c a l
V o l . 2, A c a d e m i c P r e s s , 1 9 6 5 .
2.
V e r Plank, W.E. , 'Salt in California', California
D e p a r t m e n t o f Nat u r a l Resources, Div. Mines, B u l l e ­
t i n No. 175, 1958.
3.
Kaufmann,
4.
f t r o , J o h n L. , ' M n e r a l Ite s o u r c e s
E l s e v i e r Publications, Amsterdam,
5.
F L e d e l n e n n , H.W. , fit D i a m o n d H.W. , ' S o l a r S a l t ' ,
Encyclopaedia of M a r i n e Resources, p p 594-597, V a n
N o s t r a n d - Reinhold, N e w Yo r k , 1969.
6.
B o n y t h o n C.W., 'Factors d e t e r m i n i n g t h e r a t e o f
s o lar e v a poration i n t h e p r o d u c t i o n o f salt' , P r o ­
ceedings of the Second World Salt Symposium, C l eve­
l a n d , C h i o , US A , 1 9 6 4 .
7.
Febvre,
'The p r o & i c t i o n o f sea salt i n
S o c i e t e I n d i s t r i e l l e fit C a n m e r c i e l e d e s
Midi, Paris, France, 1962.
CHAPTER
IV;
D.W.,
EVALUATION OF
op
Oceanography',
cit.
POTENTIAL
SOLAR
o f t h e Sea',
Holland, 1964.
SALT
India' ,
Selins du
SITES
1.
B r a d l e y , H.L. & Langill,
‘N e w D i m e n s i o n s f o r S o l a r
E v a p o r a t i o n Aialysis* , VI tbrld Salt Symposium, № y
1983.
2.
G a r r e t t , D. E . , ’F a c t o r s i n t h e d e s i g n o f s o l a r s a l t
plants', p a r t s I ( II, P r o c e e d i n g s o f t h e Second
W o r l d S a l t S y m p o s i u m , V o l . 2, S e c t i o n 4, C l e v e l a n d ,
Chio, USA, 1964.
3.
Bonython,
4.
forth tenual, U n i t e d States D e p a r t m e n t o f t h e
Interior, B ureau o f Reclamation, F i r s t R e v i s e d
t i o n , 1963.
C . W . , o p cit.
5.
Lambe, W.T. , 'Soil T e s t i n g f o r
W i l e y (> S o n s , N e w Y o r k , 1 9 5 1 .
C H A P T E R V:
SMALL AND
1.
B i a t t , R.B. , ' hfcnuf a c t u r e o f c o m m o n s a l t b y s e r i e s
f e e d i n g system', Salt R e s e a r c h a n d Industry, Vol.
II, N o . 7, p p 9 - 1 2 , 1 9 7 5 .
MEDIUM
SCALE
Engineers',
Edi­
PRODUCTION
OF
John
SALT
- 168 -
2.
Block, M.R., etc., 'Solar e v a p o r a t i o n of salt
b r ines', I n d u s t r i a l & E n g i n e e r i n g Chemi s t r y , Vol.
43, p p 1 5 4 4 - 5 3 , 1 9 5 1 .
3.
Bonython, C.W., 'Factors determining the rate of
s o l a r e v a p o r a t i o n in t h e p r o d u c t i o n of s a l t ’ . W o r l d
S a l t S y m p o s i u m #2, p p 1 5 2 - 1 6 7 , 1 9 6 4 .
4.
Bradley, H.L., 'Maniobra
agua', 1/15/81.
5.
Davis,
salt'.
6.
Davis, J.S., 'Biological communities
e n r i c h e d s a l i n a ' , A q . B u i . 4 : 2 3 , 42,
7.
F e r g u s o n , J., 'The r a t e o f n a t u r a l e v a p o r a t i o n f r o m
shallow ponds', Australian Journal of Scientific
R e s e a r c h , S e r i e s A, V o l . 5, p p 3 1 5 - 3 3 0 , 1 9 5 2 .
8.
d e F l e r s , P. , ' S o l a r
S ymposium, p p 51-61,
9.
d e F l e r s , P . , 'A n e w p r o c e s s
salt', W o r l d Salt Symposium,
10.
F r e e , K . W . , 'T h e p r o d u c t i o n o f s o l a r s a l t ' , T r a n s ­
a c t i o n s I n s t n . C h e m . E n g . , V o l . 36, p p 1 1 5 - 1 2 2 ,
1958.
11.
G a r r e t t , D . E . , ' F a c t o r s in t h e d e s i g n o f s o l a r s a l t
p l a n t s , P a r t II, O p t i m u m o p e r a t i o n o f s o l a r p o n d s ' ,
W o r l d S a l t S y m p o s i u m , p p 176-187, 1969.
12.
G a l l o n e , P ., ' E x t r a c t i o n o f s o d i u m c h l o r i d e f r o m
sea w a t e r ' , T r a n s l a t i o n of U l l m a n n E n c y c o l p a d i e der
t e c h n i s c h e n Chem., 4th E d i t i o n , p p 1-20.
13.
G a r r e t t , D . E . , ' F a c t o r s in t h e d e s i g n o f s o l a r s a l t
p l a n t s , P a r t II, O p t i m u m o p e r a t i o n o f s o l a r p o n d s
a n d P a r t I, P o n d l a y o u t a n d c o n s t r u c t i o n ' , W o r l d
S a l t S y m p o s i u m , p p 1 6 8 - 1 7 5 , 1970.
14.
Gibs o n , U.I., a nd S i n g e r R . D . , 'Small W e l l s M a n ­
ual', A g e n c y for I n t e r n a t i o n a l D e v e l o p m e n t , USA,
1969.
15.
G u r u n u t h & S o n s , ’D e t a i l e d P r o j e c t R e p o r t o n t h e
d e v e l o p m e n t of a large salt w o r k s in B a l a s o r e D i s ­
t r i c t , O r i s s a , India, 1981.
J.S.,
World
Solmuera
y
Salina
Cumer-
'Importance of m i c r o o r g a n i s m s in solar
S a l t S y m p o s i u m , 4 t h , V o l . 2, 1 9 7 4 .
of a n u t r i e n t
1978.
salt production',
1959.
World
for was h i n g
1969.
of
Salt
solar
-169-
16.
H a r b e c k , G . E . , 'The e f f e c t of s a l i n i t y o n e v a p o r a ­
tion', G e o l o g i c a l S u r v e y P r o f e s s i o n a l P a p e r 272-A,
p p 1-6, 1955.
17.
H a r b e c k , G . E . , 'A p r a c t i c a l f i e l d t e c h n i q u e f o r
measuring reservoir evaporation utilising masst r a n s f e r theory', U.S. G e o l o g i c a l P r o f e s s i o n a l
P a p e r s , p p 1 0 1 - 1 0 5 , 1962.
18.
Hughes, G.H., 'Analysis of techniques u sed to
m e a s u r e e v a p o r a t i o n f r o m S a l t o n sea, C a l i f o r n i a ' ,
G e o l o g i c a l Survey Professional P a per 272-H,
p p 151-176, 1967.
19.
J a c a b s o n , R . N . , a nd Ore, F., 'Solar p o n d M o d e l l i n g ' ,
Proceedings of the Fourth W o rld Salt Symposium,
H o u s t o n , T e x a s , U S A , V o l . II, 1 9 7 3 .
20.
21 .
22.
Jones, A.G., etc.,
f i e l d ' , p p 1-16.
'Biotechnology
solar
salt
K a l l e r u d , M.J . , 'Advances in s o l a r s a l t - s o l a r
e v a p o r a t i o n i n m u l t i c o m p o n e n t p r o c e s s ', W o r l d
S y m p o s i u m , p p 41-46, 1964.
Salt
Kohler, M . A . , 'Lake an d p a n e v a p o r a t i o n (Lake
H e f n e r ) ', G e o l o g i c a l S u r v e y P r o f e s s i o n a l P a p e r
p p 1 2 7 - 1 5 6 , 1952.
269,
23.
Masuzawa, T . , 'Impurities contained inside the
c r y s t a l s o f s o l a r a n d v a c u u m e v a p o r a t e d s h i t s ',
W o r l d S a l t Sympo s i u m , p p 463-473, 1979.
24.
M c A r t h u r , J . N . , 'An a p p r o a c h t o p r o c e s s a n d q u a l i t y
c o n t r o l r e l e v a n t t o s o l a r s a l t f i e l d o p e r a t i o n s in
the northwest of western A u s t r a l i a ’, W o r l d Salt
S y m p o s i u m , p p 3 2 6 - 3 3 4 , 1979.
25.
Mehta, M.J., 'Design & Layout of salt works',
P r o c e e d i n g s o f t h e T r a i n i n g C o u r s e in S a l t
Technology, Salt Department, G o v e r n m e n t of India,
1981.
26.
Meyers, D.M., and Bonython, C.W., 'The t h e o r y of
r e c o vering salt from sea w a t e r b y solar evaporation',
J o u r n a l A p p l . C h e m . 8, p p 2 0 7 - 2 1 9 , 1 9 5 8 .
27.
Penmann, H.L., 'Natural e v a p o r a t i o n from
water, b a r e soil and grass', Proc. Royal
1948(A) 193, p p 120-145.
open
Soc.
- 170 -
28.
Rands, D.G., 'The e f f e c t of m a g n e s i u m o n t h e solar
evaporation process', World Salt Symposium, pp
359-363, 1979.
29.
Rohw e r , C., ' E v a p o r a t i o n f r o m s a l t s o l u t i o n s and
f r o m o i l c o v e r e d w a t e r s u r f a c e s ' . J o u r n a l o f A g.
R e s e a r c h U S A , V o l . 46, p p 7 1 5 - 7 2 9 , 1 9 8 3 .
30.
Rothbaum, H.P., 'Vapor pr e s s u r e of sea w a t e r
concentrates'. Chemical & Engineering Chemistry,
V o l . 3, N o . 1, p p 5 0 - 5 2 .
31.
Sammy, Nathan, 'Biological systems in north-western
A u s t r a l i a n solar salt fields'. W o r l d Salt Symposium,
1983.
32.
S c h n e i d e r , J. a n d M u n t e r , H . A . , ' S a l t w o r k s —
nat u r a l l a b oratories for m i c r o b i o l o g y and
g e o c h e m i c a l i n v e s t i g a t i o n s d u r i n g e v a p o r a t i o n of
s e a w a t e r ’ , W o r l d S a l t S y m p o s i u m , p p 1-20, 1979.
33.
Sutton, O . G . , 'Wind S t r u c t u r e a n d e v a p o r a t i o n
t u r b u l e n t a t mosphere', Proc. R o y a l Society,
p p 701-722, 1934.
34.
S u t t o n , W . G . , ' On t h e e q u a t i o n o f d i f f u s i o n i n a
t u r b u l e n t me d i a ' , Proc. Royal S ociety, 1943.
35.
Union
36.
V e r Pl a n c k , W.E., 'Salt in C a l i f o r n i a ' ,
C a lif., Div. N a t u r a l R e s o u r c e s B u l l e t i n
p p 1-168, 1957.
37.
'Design of small canal
t h e I n t e r i o r , 1983.
C H A P T E R VI:
MODERNISATION AND MECHANISATION
SALT INDUSTRY
Salinera
de
España,
'Memoria',
structures',
Ensal,
U.S.
OF T H E
in
a
1979.
State
175,
Dept,
of
of
SOLAR
1.
M a j e e t h i a , K.M., Thacker, B.G., Gohil, M . M . , and
Rao, K . S . , ' M e c h a n i c a l E q u i p m e n t for D e v e l o p m e n t of
S a l t I n d u s t r y ’, P r o c e e d i n g s of the I n t e r n a t i o n a l
S y m p o s i u m for Salt & Mar i n e Chemicals, Bhavnagar,
India, 1982.
2.
G e n t y , P i e r r e , ' V a rious T y p e s of M e c h a n i c a l
H a r vesters for Small and M e d i u m Size Salt Works',
P r o c eedings of the International S y m p o s i u m for Salt
an d M a r i n e C h e m i c a l s , B h a v n a g a r , India, 1982.
3.
Japan Consulting
Ja p a n , 1976.
Institute,
'Bittern
Industry
in
Garrett, D.E., 'Factors in the d e s i g n o f S o l a r Salt
plants - Part IV - By-product chemical Recovery,
P r o c e e d i n g s of the T h i r d S y m p o s i u m o n Salt, T he
N o r t h e r n O hio Geological Societv, Clevel a n d , Ohio,
USA, 1970.
W e i n b e r g e r , A.J. et al., 'Saline W a t e r C o n v e r s i o n
and its by-products'. Chemical E n g ineering Progress,
V o l . 60, N o . 1 1, 1 9 6 0 .
Kawate Hideo, Seto Toshiki, Takiguci M i t s h u h i k o and
M i y a s i K u t s u h i k o , 'Salt f r o m sea w a t e r b y Ion
Exchange Electrodialyses p r o c e s s ' , P r o c e e d i n g s of
the International Symposium for salt and m a r i n e
c h e m i c a l s , B h a v n a g a r , India, 1982.
T a l l m a d g e , J . A . , Butt, J.B. a n d S o l o m o n , H . J . ,
' M i n e r a l s f r o m sea salt', I n d u s t r i a l & E n g i n e e r i n g
C h e m i s t r y , V o l . 56, N o . 7, 1 9 6 4 .
Gurunath, M.M., Venkatesh Mannar, M.G. and
Diamond, H . W . , 'Fortification of salt w i t h iron',
P r o c e edings of the Fou r t h World Salt Symposium,
H o u s t o n , T e x a s , U S A , V o l . 2, 1 9 7 3 .
D a v i s , J o s e p h S., ' I m p o r t a n c e o f M i c r o - o r g a n i s m s
solar salt production', Proceedings of the W o rld
S y m p o s i u m , H o u s t o n , T e x a s , U S A , V o l . 2, 1 9 7 3 .
in
Salt
d e F l e r s , P . , d e S a b o u l i n , B ., a n d C l a i n , J . ,
'Harvest of solar salt at S a l i n e de G i r a u d ' ,
P r o c e e d i n g s of the F o u r t h W o r l d Salt Symposium,
H o u s t o n , T e x a s , U S A , V o l . 2, 1 9 7 3 .
Rocha, M., Regato, E . , an d A l m e i d a , F., ' E v o l u t i o n
of H a r v e s t i n g M e t h o d s a n d M e c h a n i s a t i o n in S m a l l
salt works', Proceedings of the F i f t h World Salt
S y m p o s i u m , H a m b u r g , G e r m a n y , V o l . 2, 1 9 7 8 .
- 172 -
APPENDIX
SOURCES
OF
INFORMATION
-
II
ON THE
SOLAR
SALT
INDUSTRY
1.
S a l t I n s t i t u t e , 206, N o r t h W a s h i n g t o n
S t r e e t , A l e x a n d r i a , V i r g i n i a 22314 U S A
2.
S o l a r Lobby, 1001, C o n n e c t i c u t Avenue,
N W F i f t h Floor, W à s h i n g t o n DC 20034 U S A
3.
UNIDO, Vien n a International Centre,
B o x 300, A - 1 4 0 0 , V i e n n a , A u s t r i a
Jj.
Central Sale & Marine Chemicals Research
I n s t i t u t e , B h a v n a g a r 364 002, India.
5.
E u r o p e a n Committee for the Study of Salt,
11 Bis, A v . V i c t o r Hugo, 75116 Paris,
France.
6.
J a p a n C o n s u l t i n g Institute, Nikkat su
International Building, 1-Chome, Yurakucho,
Chiyoda-ku, Tokyo, Japan.
7.
Chemicals
Industry,
Canberra,
8.
B u r e a u of M i n e s (Non M e t a l l i c M i n e r a l s
Section) U.S.Department of the Interior,
2401, E S t r e e t , NW, W a s h i n g t o n , DC 2 0 2 4 1
USA.
P.O.
Section, Office of Secondary
Government of Australia,
Australia.
- 173 -
APPENDIX
CONFERENCES
ON
SOLAR
-
III
SALT
& ALLIED
TOPICS
1.
World Salt Symposia:
Held once In 5 years.
F i v e h e l d so far.
(Last h e l d in 1978 In Hamburg,
West Germany)
Next in Toronto, Canada In May
1983For Information contact Northern Ohio
Ge o l o g i c a l Society, C/o. D e p a r t m e n t of Geology,
Case Western Reserve University, Cleveland,
О Н 1Й106, USA.
2.
International Symp o s i u m on Salt & Marine
C h e m i c a l s h e l d o n c e s o f a r i n M a r c h 198 2 in
Bhavnagar, India.
F or information contact
Central Salt & Marine Chemicals Research
Institute, Bhavnagar, India.
TRAINING
PROGRAMMES
T r a i n i n g p r o g r a m m e s c an n o r m a l l y be fixed
o n a G o v e r n m e n t to G o v e r n m e n t b a s i s w i t h t h e
assistance of the UNIDO.
F o r instance, the
Government of India has trained sponsored
candidates from several foreign governments.
F o r i n f o r m a t i o n w r i t e to the Salt C ommissioner,
G o v e r n m e n t o f India, J a i p u r , Rajasthan, India.
Private Companies do not normally offer
training p rogrammes.