EUROPEAN COMMISSION
DIRECTORATE-GENERAL JRC
JOINT RESEARCH CENTRE
Institute for Prospective Technological Studies
Sustainability in Industry, Energy and Transport
European IPPC Bureau
Additional Information
submitted during the information exchange on
Large Volume Inorganic Chemicals – Solid and Others Industry
June 2005
Edificio EXPO, c/ Inca Garcilaso s/n, E-41092 Sevilla - Spain
Telephone: direct line (+34-95) 4488-284, switchboard 4488-318. Fax: 4488-426.
Internet: http://eippcb.jrc.es; Email: [email protected]
Additional Information submitted during the information
exchange on Large Volume Inorganic Chemicals – Solid and
Others Industry
INTRODUCTION ..................................................................................................................................VII
1
SELECTED ILLUSTRATIVE LVIC-S INDUSTRY PRODUCTS ..............................................1
1.1
Aluminium chlorides ..................................................................................................................1
1.1.1
Polyaluminium chloride ...................................................................................................1
1.1.1.1
General information..................................................................................................1
1.1.1.2
Process description ...................................................................................................2
1.1.1.2.1
Aluminium hydroxy chloride............................................................................2
1.1.1.2.2
Aluminium hydroxy chloride sulphate .............................................................2
1.1.1.3
Current consumption and emission levels ................................................................3
1.1.1.3.1
Aluminium hydroxy chloride............................................................................3
1.1.1.3.2
Aluminium hydroxy chloride sulphate .............................................................3
1.1.2
Aluminium chloride (solution) .........................................................................................4
1.1.2.1
General information..................................................................................................4
1.1.2.2
Process description ...................................................................................................4
1.1.2.3
Current consumption and emission levels ................................................................5
1.2
Aluminium sulphate....................................................................................................................6
1.2.1
General information..........................................................................................................6
1.2.1.1
Introduction ..............................................................................................................6
1.2.1.2
Information on aluminium sulphate – inorganic coagulants.....................................6
1.2.2
Process description ...........................................................................................................7
1.2.3
Current consumption and emission levels ........................................................................8
1.2.3.1
Consumption of raw materials ..................................................................................8
1.2.3.2
Major environmental impacts ...................................................................................8
1.3
Chromium compounds..............................................................................................................11
1.4
Ferric chloride...........................................................................................................................12
1.4.1
General information........................................................................................................12
1.4.1.1
Introduction – ferric chloride (FeCl3) .....................................................................12
1.4.1.2
Background information on ferric chloride (FeCl3)................................................12
1.4.2
Process description .........................................................................................................13
1.4.2.1
Ferric chloride solution (scrap iron + chlorine) ......................................................13
1.4.2.2
Ferric chloride solution (scrap iron + hydrochloric acid + chlorine) ......................13
1.4.2.3
Ferric chloride solution (spent FeCl2 liquor + chlorine) .........................................14
1.4.2.4
Ferric chloride solution (iron ore + hydrochloric acid)...........................................14
1.4.2.5
Ferric chloride solution (iron ore + hydrochloric acid + oxidation) .......................15
1.4.3
Current consumption and emission levels ......................................................................16
1.4.4
Special features and limiting factors...............................................................................16
1.4.5
Techniques to consider in the determination of BAT .....................................................17
1.4.6
Emerging techniques ......................................................................................................17
1.5
Potassium carbonate .................................................................................................................18
1.6
Sodium sulphate .......................................................................................................................19
1.6.1
General information........................................................................................................19
1.6.1.1
Introduction ............................................................................................................19
1.6.1.2
Basic data on sodium sulphate production..............................................................19
1.6.2
Industrial processes used ................................................................................................21
1.6.2.1
Fibres process (Na2SO4 production from the viscose-fibre process) ......................21
1.6.2.2
MESSO process (from Glauber’s salt) ...................................................................22
1.6.2.3
Chromium process ..................................................................................................23
1.6.2.4
Mannheim furnace process (hydrochloric acid)......................................................24
1.6.2.5
Methionine process.................................................................................................25
1.6.2.6
Formic acid process ................................................................................................27
1.6.3
Current emission and energy consumption levels ..........................................................28
1.6.4
Techniques to consider in the determination of BAT .....................................................29
1.7
Zinc chloride.............................................................................................................................31
1.8
Zinc sulphate.............................................................................................................................32
1.9
Sodium bisulphate ....................................................................................................................33
2
PURIFICATION OF NON-FERTILISER GRADE WET PHOSPHORIC ACID (PARTIAL
INFORMATION) .............................................................................................................................. 1
2.1
Inorganic Phosphates – Introduction .......................................................................................... 1
2.2
Purification of non-fertiliser grade wet phosphoric acid – the options....................................... 3
REFERENCES........................................................................................................................................... 5
GLOSSARY OF TERMS AND ABBREVIATIONS .............................................................................. 9
List of figures
Figure 1.1:
Figure 1.2:
Figure 1.3:
Figure 1.4:
Figure 1.5:
Figure 1.6:
Figure 1.7:
Figure 1.8:
Figure 1.9:
Figure 1.10:
Figure 1.11:
Figure 1.12:
Figure 1.13:
Figure 1.14:
Figure 1.15:
Figure 1.16:
Process flow diagram – manufacture of aluminium hydroxy chloride...................................2
Process flow diagram – manufacture of aluminium hydroxy chloride sulphate ....................3
Process flow diagram – manufacture of aluminium chloride solution ...................................4
Process flow diagram of aluminium sulphate production ......................................................8
A chromium chemical complex ...........................................................................................11
Process diagram - production of FeCl3 based on scrap iron and chlorine ............................13
Process diagram - production of FeCl3 based on scrap iron, HCl and chlorine...................14
Process diagram - production of FeCl3 based on iron ore and hydrochloric acid.................15
Process diagram – production of FeCl3 based on iron ore and HCl and oxidation ..............16
Flow scheme of sodium sulphate production from the viscose-fibre process ......................22
Flow scheme of sodium sulphate production by the Messo process ....................................23
Flow scheme of the production of sodium sulphate from the chromium process ................24
Flow scheme of the production of Na2SO4 by the Mannheim furnace process....................25
Flow scheme of the production of sodium sulphate from the methionine process...............27
Flow scheme of sodium sulphate production in the formic acid process .............................28
Technological network of zinc chemical compounds ..........................................................31
List of tables
Table 1.1:
Table 1.2:
Table 1.3:
Table 1.4:
Table 1.5:
Table 1.6:
Table 1.7:
Table 1.8:
Table 1.9:
Table 1.10:
Table 1.11:
Table 1.12:
Table 1.13:
Typical consumption and emission values – aluminium hydroxy chloride ........................... 3
Typical consumption and emission values – aluminium hydroxy chloride sulphate ............. 3
Typical consumption and emission values – aluminium chloride solution............................ 5
Major applications of aluminium sulphate ............................................................................ 7
Typical energy consumption and emission values for liquid aluminium sulphate ................ 9
Typical energy consumption and emission values for solid aluminium sulphate .................. 9
Location and capacities of FeCl3 plants in the EU............................................................... 12
Consumption and emission values in the production of ferrous chloride ............................ 16
Sodium sulphate production in Europe................................................................................ 20
Sodium sulphate production – emissions to air (aggregated data: min – max).................... 28
Sodium sulphate production – emissions to water (aggregated data: min – max) ............... 29
Sodium sulphate production – solid residues (aggregated data: min –max) ........................ 29
Sodium sulphate production - energy consumption (aggregated data: min - max).............. 29
Introduction
INTRODUCTION
The information contained in this document was submitted as part of the information exchange
on BAT for the production of Large Volume Inorganic Chemicals – Solid and Others (LVIC-S).
However, it was either submitted very late in the process or insufficient information is available
to draw BAT conclusions for the nine ‘selected illustrative’ LVIC-S industry products included
in this document (see the content list).
In order not to lose this partial information, it is made available here.
It must be stressed, however, that this document has not been fully peer reviewed and the
information within is not validated nor endorsed by the TWG on LVIC-S or by the European
Commission, it is meant for information, only.
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
1 SELECTED ILLUSTRATIVE LVIC-S INDUSTRY PRODUCTS
1.1
Aluminium chlorides
In principle, the information contained in this section relates to aluminium chlorides, which are
used as inorganic coagulants. Aluminium chloride is also extensively utilised in its anhydrous
form. In 1984 approx. 30000 tonnes was produced in the US and approx. 50000 tonnes in
Western Europe [48, W. Buchner et al, 1989].
Anhydrous aluminium chloride is mainly used as a catalyst in organic chemistry, essentially as
an alkylation catalyst, either in fine chemistry, or in the production of commodity organics like
ethylbenzene in competition with e.g. solid catalysts. Its significance in the petrochemical
industry has strongly decreased with the advent of zeolite-based catalysts [6, CEFIC, 2002].
It can be produced by two process routes:
From aluminium
This process is based on the reaction of gaseous chlorine injected into a molten aluminium bath
at a typical temperature of 800 °C. The equation of the reaction is:
2 Al + 3 Cl2 F 2 AlCl3
The chlorine conversion is very rapid and complete. Aluminium chloride leaves the reactor as a
vapour, which is condensed to a solid on a cooled surface. The solid aluminium chloride is
conditioned by crushing and sieving, then stored in bulk or packaged and finally shipped.
Air emissions from the vent in the aluminium chloride condensation reactor and from the
conditioning, handling and storage systems contain chlorine, hydrochloric acid and aluminium
chloride. Emissions to water are essentially from the vents scrubbers, and include hydrochloric
acid and dissolved/suspended aluminium compounds. Waste generation is very small and
includes essentially aluminium hydroxide sludge recovered from waste water treatment.
From aluminium oxide
This process, which is no longer used in Europe, is based on the carbo-chlorination of
aluminium oxide according to the following reaction:
2 Al2O3 + 3 C + 6 Cl2
F 3 CO2 + 4 AlCl3
In addition to the environmental issues of the aluminium process, generic CO, SOx and NOx air
emissions occur, while the formation of some chlorinated organics is possible [6, CEFIC, 2002].
1.1.1
1.1.1.1
Polyaluminium chloride
General information
Product Name :
CAS number :
Polyaluminium chloride
1327-41-9 (Aluminium hydroxy chloride) and
39290-78-3 (Aluminium hydroxy chloride sulphate)
Polyaluminium chloride is a very common aluminium salt, the major uses of which are:
Use
Water Treatment
Paper Additive
Application
As a coagulant for drinking, industrial waste and municipal waste water
As a retention and fixing agent, and a sizing additive
1
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
Due to different types of polyaluminium chloride (PAC) with different aluminium contents, all
tonnage related data are normalised to one common PAC with a content of 9 % aluminium and
are calculated on this basis. About 520000 tonnes of PAC were produced in Europe in 2002 at
about 17 locations [89, CEFIC-INCOPA, 2004].
1.1.1.2
Process description
1.1.1.2.1
Aluminium hydroxy chloride
Aluminium hydroxy chloride is formed directly by the digestion of aluminium hydroxide and
hydrochloric acid in an under-stoichiometric reaction. The reaction is carried out at a
temperature between 140 and 160 °C and pressure between 3 and 5 bars. After the reaction,
insoluble aluminium hydroxide is removed by filtration and is used again at the beginning of the
process. The clear liquid is conditioned with water to become the finished product of a well
defined quality.
Al(OH)3 + HCl F Alx(OH)yClz + H2O
The process diagram of the manufacture of aluminium hydroxy chloride is given in Figure 1.1.
Al(OH)3
Reaction
Filtration
PAC
HCl
Unreacted
Al(OH)3
Figure 1.1: Process flow diagram – manufacture of aluminium hydroxy chloride
[89, CEFIC-INCOPA, 2004]
1.1.1.2.2
Aluminium hydroxy chloride sulphate
Aluminium hydroxy chloride sulphate is formed by the digestion of aluminium hydroxide with
hydrochloric acid and sulphuric acid. The reaction is carried out at a temperature between
105 and 115 °C. The reaction solution is partially neutralised by CaCO3 slurry to remove
excessive sulphate by forming gypsum (CaSO4.2 H2O). The mother liquor is separated from the
gypsum by filtration. The gypsum is washed and the washing water is used to condition the
product.
Al(OH)3 + HCl + H2SO4 + CaCO3
F
Alp(OH)qClr(SO4)s + H2O + CaSO4 + CO2
The process diagram of the manufacture of aluminium hydroxy chloride sulphate is given in
Figure 1.2.
2
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
Al(OH) 3
H 2SO 4
CaCO 3
Reaction
Neutralisation
HCl
Washing
water
Filtration
Conditioning
Water
Mother
liquor
PAC
CaSO 4 *2H 2 O
Figure 1.2: Process flow diagram – manufacture of aluminium hydroxy chloride sulphate
[89, CEFIC-INCOPA, 2004]
1.1.1.3
Current consumption and emission levels
1.1.1.3.1
Aluminium hydroxy chloride
Typical consumption and emission values are given in Table 1.1.
Consumption of energy and water
Energy consumption kWh/t product
600
Water consumption m3/t product
1.5
Emissions to air
Chemical
Emission kg/t product
Emission concentration limit
HCl
0.01
500 mg/Nm3
Emissions to water
Chemical
Emission kg/t product
Comments
HCl
0.8
Water is mostly recycled
Waste to land
Chemical
Waste kg/t product
Comments
Al(OH)3
12
Mostly recycled
Table 1.1: Typical consumption and emission values – aluminium hydroxy chloride
[89, CEFIC-INCOPA, 2004]
1.1.1.3.2
Aluminium hydroxy chloride sulphate
Typical consumption and emission values are given in Table 1.2
Consumption of energy and water
Energy consumption kWh/t product
200
Water consumption m3/t product
15
Emissions to air
Chemical
Emission kg/t product
Emission concentration limit
HCl
0.2
500 mg/Nm3
Emissions to water
Chemical
Emission kg/t product
Comments
HCl
35
Scrubber water
CaSO4
3800
Water with gypsum
Waste to land
Chemical
Waste kg/t product
Comments
Gypsum, Al(OH)3
1.5
Table 1.2: Typical consumption and emission values – aluminium hydroxy chloride sulphate
[89, CEFIC-INCOPA, 2004]
3
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
There are no special features or limiting factors to be mentioned [89, CEFIC-INCOPA, 2004].
There is a wide range of air and water emissions. This depends on the type of gas scrubber.
Some scrubbers can recycle water by concentrating hydrochloric acid and re-using it in the
process. Therefore, waste water emission from scrubber water is minimised.
1.1.2
Aluminium chloride (solution)
1.1.2.1
General information
Product Name :
CAS number :
Aluminium chloride solution
Not established for aluminium chloride solution
Aluminium chloride is a very common aluminium salt, the major uses of which are:
Use
Water treatment
Application
As a coagulant for drinking, industrial waste and municipal waste water
About 25000 tonnes of aluminium chloride (as inorganic coagulant) were produced in 2002 at
three locations.
1.1.2.2
Process description
Aluminium chloride solution is formed directly by the digestion of aluminium hydroxide and
hydrochloric acid in a stoichiometric reaction. The reaction is carried out at a temperature
between 100 and 110 °C. After the reaction, insoluble aluminium hydroxide is removed by
filtration and is used again at the beginning of the process. The clear liquid is conditioned with
water to become the finished product of a well defined quality.
Al(OH)3 + 3HCl
F
AlCl3 + 3H2O
The process flow diagram for the manufacture of aluminium chloride solution is given in
Figure 1.3.
Al(OH)3
Reaction
Filtration
HCl
Unreacted Al(OH)3
Figure 1.3: Process flow diagram – manufacture of aluminium chloride solution
[89, CEFIC-INCOPA, 2004]
4
AlCl3
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
1.1.2.3
Current consumption and emission levels
Typical consumption and emission values are given in Table 1.3.
Consumption of energy and water
Energy consumption kWh/t product
Water consumption m3/t product
Emissions to air
Emission kg/t product
Chemical
HCl
0.02
Emissions to water
Chemical
Emission kg/t product
HCl
0.1
Waste to land
Chemical
Waste kg/t product
Al(OH)3
0.1
100
3
Emission concentration limit
10 mg/Nm3
Comments
Comments
Undissolved raw material
Table 1.3: Typical consumption and emission values – aluminium chloride solution
[89, CEFIC-INCOPA, 2004]
There are no special features or limiting factors to be mentioned [89, CEFIC-INCOPA, 2004].
There is a wide range of air and water emissions. This depends on the type of gas scrubber.
Some scrubbers can recycle water by concentrating hydrochloric acid and re-using it in the
process. Therefore, waste water emission from scrubber water is minimised.
5
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
1.2
1.2.1
Aluminium sulphate
General information
1.2.1.1
Introduction
With a worldwide production of 2.9 million tonnes in 1982, aluminium sulphate is the most
important aluminium compound after aluminium oxide and hydroxide, these latter compounds
are already covered in the Non-Ferrous Metals BREF.
The most important producers are the US (with 1.1 million tonnes in 1984 on the basis of 17 %
Al2O3, Western Europe (with 0.9 million tonnes per year) and Japan (with 0.8 million tonnes per
year on the basis of 14 % Al2O3) [48, W. Buchner et al, 1989].
Aluminium sulphate is a substance essentially used in water treatment as a flocculating agent
and in the paper industry. Aluminium sulphate is also the starting material for other aluminium
compounds [13, EIPPCB, 2000]. The commercial product is either a solid hydrated salt, whose
formula is typically Al2(SO4)3.13 to 15 H2O. It is shipped in flakes, powder or blocks, or as an
8 % (as Al2O3) solution in water [6, CEFIC, 2002].
Aluminium sulphate is industrially produced by the reaction of aluminium hydroxide (or other
aluminium raw materials such as bauxite or kaolin) with sulphuric acid. In Europe, the largest
part of aluminium sulphate is produced by the reaction of sulphuric acid with wet or dry
aluminium hydroxide according to the following reaction:
2Al(OH)3 + 3 H2SO4
F
Al2(SO4)3 + 6H2O
This reaction is the common trunk of all processes, and it is typically carried out in a stirred
batch reactor at a temperature of 110 – 120 °C and under atmospheric pressure. The resulting
solution is treated differently according to the shipment mode:
•
•
for shipment as a solution, the Al2O3 concentration of the mixture leaving the reactor is
simply adjusted, and the resulting solution is clarified (by filtration). This process only
generates minor air and water emissions
for shipment as a solid, the mixture leaving the reactor is sent either to a crystalliser, a flaker
or a solidification box according to the shape required. Further treatments may include
crushing, milling, sieving before packaging. This process generates almost clean waste
water from the concentration steps and air emissions containing particulate from solid
handling.
Other feedstocks e.g. bauxite or clays, are industrially used, but as they are not as pure as
aluminium hydroxide, their processing either leads to a less pure aluminium sulphate (e.g.
containing soluble iron sulphate or suspended solids) or generates solid wastes. Also, spent
aluminium salts solutions (e.g. from aluminium surface treatment activities) can be a source of
small amounts of aluminium sulphate used for the local markets [6, CEFIC, 2002].
1.2.1.2
Information on aluminium sulphate – inorganic coagulants
The substances covered are all based on aluminium sulphate in a solid or liquid pure form or
containing additives, mainly iron, in the form of iron sulphate. In both the solid and liquid form,
the categories can be split into three groups:
•
•
•
6
iron free
low iron
iron blends.
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
Solid products have a concentration of between 7 – 9.3 % Al with a typical concentration of
9.1 % equivalent to 14 crystal water. Concentration in liquid products is 3.5 – 4.5 % Al. The
iron content in the substances can typically vary between 0 – 3 % as Fe.
Solid products are produced in every fraction from fine powder up to blocks of about 10 kg.
Product Name :
Derivatives:
Aluminium sulphate Al2(SO4)3
Low iron aluminium sulphate, iron containing aluminium sulphate,
aluminium basic sulphate.
As illustrated in Table 1.4, aluminium sulphate is a very common product that is used in the
following major areas:
Use
Drinking water treatment
Sewage water treatment
Paper industry
Other applications
Share
~ 30 %
~ 10 %
~ 40 %
~ 20 %
Application
Coagulant for purification
Coagulant for purification and phosphorus removal
Coagulant for water purification and paper sizing
Pigment production, cement industry, detergent, fire
extinguishers, etc.
Table 1.4: Major applications of aluminium sulphate
[50, CEFIC-INCOPA, 2004]
Due to its low value and high production volumes, aluminium sulphate is produced in most
European countries to cover the local demand. The number of production units within Europe is
about 65 plants. From these, about 15 units are outside the EU-15. The total capacity is at the
level of 1.2 million tonnes calculated as solid equivalents of 9.1 % Al. The capacity utilisation is
on average 50 %, which would bring the total European market to about 600000 tonnes, i.e.
20 – 25 % of the total world market [50, CEFIC-INCOPA, 2004].
1.2.2
Process description
Aluminium sulphate comes directly from the digestion of aluminium containing raw materials
with sulphuric acid.
2Al(OH)3 + 3H2SO4 F Al2(SO4)3 + 6H2O
The most common aluminium raw material is by far aluminium hydroxide, a product
originating from the Bayer process, where bauxite is used as a raw material for the production
of pure aluminium hydroxide or oxide. For the production of iron containing aluminium
sulphate products, bauxite is also used as a source for aluminium raw material.
The digestion with sulphuric acid normally takes place at atmospheric pressure and at a
temperature between 110 – 120 ºC. In some cases pressure digestion is also used with a
temperature up to about 170 °C. The heat necessary for the process comes from the exothermic
reaction. The normal Al-concentration in the digester is in the ratio of 7 – 9 %, which means
that the boiling temperature is around 120 °C and the crystallisation temperature 105 – 110 °C.
A small amount of steam is sometimes used to avoid crystallisation and prolong the reaction.
Otherwise the energy consumption of the process is limited to pumps and agitators.
After digestion, the product is either diluted with water for a liquid product or, in a solidification
unit, cooled directly or indirectly with air or water to a solid form, which is then ground and
screened to the required particle size. Dust coming from this process is handled by filters or
scrubbers. This dust is commonly recycled through a dilution step in the production of
aluminium sulphate solution.
7
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
The use of alternatives to aluminium hydroxide, like bauxite, will create a waste coming out of
the process mainly consisting of an insoluble silica rest. This is, however, less than when
bauxite is used for the production of aluminium hydroxide [50, CEFIC-INCOPA, 2004].
In the production of aluminium sulphate products containing iron, the iron either comes directly
from the raw material (bauxite), or is separately added to the reactor, or is mixed with the final
product.
The process flow diagram of aluminium sulphate production is given in Figure 1.4.
H2SO4
Al (OH)3
Reaction
Liquid
production
Dilution
Water
Solid
production
Crystallisation
Cooling
(water or air)
Dust to
process
Rest
Filtration
Screening
Grinding
Storage
Storage
Gas
cleaning
Figure 1.4: Process flow diagram of aluminium sulphate production
[50, CEFIC-INCOPA, 2004]
If air is used in direct contact with the product, the air is cleaned in a gas cleaning system. All
dust that is separated is returned to the process [50, CEFIC-INCOPA, 2004].
1.2.3
1.2.3.1
Current consumption and emission levels
Consumption of raw materials
Consumption figures for solid aluminium sulphate are about: 50 % sulphuric acid, 30 %
aluminium hydroxide, and 20 % water. The consumption figures for liquid products are about:
20 – 25 % sulphuric acid, 12 – 15 aluminium hydroxide and 60 – 65 % water. The reaction is
almost complete, the yield of the raw materials being nearly 100 % [50, CEFIC-INCOPA,
2004].
1.2.3.2
Major environmental impacts
Typical energy and water consumption figures and emissions values for liquid aluminium
sulphate are given in Table 1.5.
8
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
Energy consumption
kWh/tonne product
<300
<40
Electricity
Other energy (estimated LPG)
Water consumption
Water consumption (m3/tonne product)
Cooling water (kWh/tonne product)
Emissions to air
Type of emission
H2SO4
Particles
Al and its compounds
Carbon dioxide
Emissions to water
Type of emission
Waste to land:
Type of waste
Filter cake (active waste)
Comments
0.7 – 1.4
(kg/tonne product)
<0.01
<0.002
<0.0002
<10
Comments
(kg/tonne product)
Comments
The process operates in a
closed system
(kg/tonne product)
<0.7
Comments
Emissions of the product
Emissions of raw materials
Table 1.5: Typical energy consumption and emission values for liquid aluminium sulphate
[50, CEFIC-INCOPA, 2004]
If bauxite is used as a raw material for liquid aluminium sulphate, this generates a waste to land
at the plant. Otherwise, there is no significant difference between iron free and low iron or iron
containing aluminium sulphate regarding consumption figures, and waste and emissions levels.
Typical energy and water consumption figures and emissions values for solid aluminium
sulphate are given in Table 1.6.
Electricity
Other energy
Energy consumption
kWh/tonne product Comments
<50
Minor energy may be used for preventing
crystallisation in the process
Water consumption
Water consumption (m3/tonne product)
0.26 – 0.46
Cooling water (kWh/tonne product)
Emissions to air
Type of emission
(kg/tonne product)
Comments
Dust
<0.01
H2SO4
<0.003
Carbon dioxide
<0.005
Al and its compounds <0.01
Emissions to water
Type of emission
(kg/tonne product)
Comments
The process operates in a closed system
Waste to land
Type of waste
(kg/tonne product)
Comments
Al sulphate
<0.01
Table 1.6: Typical energy consumption and emission values for solid aluminium sulphate
[50, CEFIC-INCOPA, 2004]
There are no significant differences in consumption figures, emissions and waste if it is iron
free, low iron or iron containing aluminium sulphate.
9
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
The following are special features and limiting factors relating to the production of aluminium
sulphate [50, CEFIC-INCOPA, 2004]:
•
•
•
•
10
the digestion process of aluminium hydroxide with sulphuric acid gives a yield of
practically 100 %, which means that the only emission from the production is some steam
coming from the reactor
as the process is exothermic, the energy consumption is negligible
grinding, screening and bagging the solid form of aluminium sulphate creates dust, but this
is taken care of by filters or scrubbers and is recycled back into the process, or sold as a fine
powder
only in the case of using bauxite as a raw material in liquid production, will there be a waste
stream coming from the process in the form of insoluble silica, which is, however, less than
when the same amount of bauxite is used for the production of aluminium hydroxide.
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
1.3
Chromium compounds
The following chromium compounds are economically important [48, W. Buchner et al, 1989]:
•
•
•
•
•
dichromates and chromates – (basic intermediate, fireworks, dyes, chromate pigments)
chromium(VI) oxide (chromic anhydride) – (metal alloys, refractory bricks, dyes)
chromium(III) oxide (the green pigment in glass, porcelain, and oil paint)
basic chromium(III) sulphate (chrome tanning agents)
chromium(VI) and(III) compounds and chromium(IV) oxide (pigments: ceramics, textiles,
magnetic pigment).
Production pathways to the important chromium compounds lead from chromium ore via the
commercially most important chromium (VI) compound sodium dichromate (dihydrate)
Na2Cr2O7.2H2O, to which the capacities of chromium chemicals are usually referred.
A chromium chemical complex is illustrated in Figure 1.5 below [85, EIPPCB, 2004].
Chromium ore (chromite Cr2O 3.FeO)
8000 TPY
Sodium dichromate
plant (Na2Cr 2O 7)
5000 TPY (1 kiln)
+ dolomite + soda ash + sulphuric acid + fuel oil
Chromium waste
(chromium mud and sodium sulphate)
5000 TPY
550 TPY
Basic chromium
sulphate Cr(SO 4)OH
plant 1000 TPY
1000 TPY
Sodium chromate
(Na2CrO 4)
plant 1000 TPY
1000 TPY
Potassium
dichromate K 2Cr 2O 7
plant 1000 TPY
1000 TPY
Chromic acid
anhydride (CrO 3)
plant 700 TPY
700 TPY
4450 TPY
650 TPY
Leather tanning,
alloys, catalysts
Chromate pigments,
chromium dyes
3800 TPY
1400 TPY
Engraving chemicals,
fireworks, dyes
2400 TPY
1200 TPY
Chrom. metal alloys,
refractory brick, dyes
1200 TPY
700 TPY
Sodium
dichromate
for salecommodity
producttanning,
dyeing
Optional chromic
acid plant
500 TPY
500 TPY
Timber preservation,
catalysts production
Note: Other chromium compounds may be manufactured at the
request such as (NH 4)2 Cr2O 7, ZnCrO 4, PbCrO 4, BaCrO 4.
Figure 1.5: A chromium chemical complex
[EIPPCB, 2004 #85], based on [BIPROKWAS, 1985-1995 #79]
No further information submitted.
11
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on LVIC-S or by the European Commission, it is meant for information, only
1.4
1.4.1
1.4.1.1
Ferric chloride
General information
Introduction – ferric chloride (FeCl3)
Of the halides of iron, only iron(II) chloride (ferrous chloride FeCl2) and iron(III) chloride
(ferric chloride FeCl3) have become commercially important [87, Ullmann's, 2001]. Ferric
chloride is muchP more important industrially than ferrous chloride.
Anhydrous iron(III) chloride (FeCl3) is industrially produced by a high temperature reaction
of dry chlorine with scrap iron (direct chlorination). Ferric chloride is also aP by-product of
some metallurgical and chemical processes, such as the chlorinating decomposition of ironbearing oxide ores. Its ready availability and cheap feedstock (iron and chlorine) have made
iron(III) chloride, especially its aqueous solution, a significant raw material for many
industries, in particular for water treatment and for the production of iron oxides or other
iron compounds – refer to the BREF on Ferrous Metals Processing Industry (FMP).
1.4.1.2
Background information on ferric chloride (FeCl3)
Product Name:
Chemical Formula
CAS number:
Ferric chloride 40 %
FeCl3
7705-08-0 (Ferric chloride solution 40 %)
Ferric chloride can be used in different applications.
A. Principal uses include:
•
•
•
•
•
•
•
turbidity reduction
colour elimination
coagulation
sludge reduction
filter conditioning
arsenic removal
metal etching.
B. Waste water treatment:
•
•
•
•
phosphate precipitation and removal
sedimentation
dewatering
sulphide based odour elimination.
The major EU ferric chloride capacities are listed in Table 1.7:
Location of the FeCl3 plants in the EU
Area 1: Benelux, Germany, Austria and Switzerland
Area 2: Italy, France, Spain, Portugal
Area 3: Nordic countries (Finland, Denmark,
Sweden, Norway), UK, Ireland, Slovenia, Hungary
Total
Number of sites
10
14
6
Capacity
550000
500000
250000
30
1300000
Table 1.7: Location and capacities of FeCl3 plants in the EU
[CEFIC-INCOPA, 2004 #112]
12
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
1.4.2
Process description
Ferric chloride can be manufactured according to the following five major process routes:
1.4.2.1
Ferric chloride solution (scrap iron + chlorine)
1.
Reactions:
Fe + 2 FeCl3
3 FeCl2
2.
3 FeCl2 + 3/2 Cl2 (g)
3 FeCl3
The scrap iron is added to a dissolving tank with a solution of ferric chloride and converted into
a ferrous chloride solution.
In the second step, the ferrous chloride solution is oxidised in a chlorination tower using Cl2 (g).
The product is divided, about 2/3 is recycled to the first stage, and about 1/3 is withdrawn as a
final FeCl3 product.
A process flow diagram illustrating the production of FeCl3 based on scrap iron and chlorine is
given in Figure 1.6 below:
W ater
Scrap iron
2/3 FeCl3 (recycled)
RE AC TO R
(Ferrous C hloride (FeC l 2 ))
Sludge
FILT R ATIO N
C l 2 (g)
CH LO R IN ATIO N
1/3 Ferric C hloride (FeC l 3 )
Figure 1.6: Process diagram - production of FeCl3 based on scrap iron and chlorine
[CEFIC-INCOPA, 2004 #112]
1.4.2.2
Ferric chloride solution (scrap iron + hydrochloric acid + chlorine)
Reactions:
1.
2.
Fe + 2HCl
FeCl2 + ½ Cl2 (g)
FeCl2 + H2
FeCl3
FeCl2 is produced by the reaction of scrap iron with hydrochloric acid at a temperature of
>80 °C, hydrogen being released to the atmosphere.
This solution is also converted into ferric chloride by using Cl2 (g) in a chlorination tower.
13
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
A process flow diagram illustrating the production of FeCl3 based on scrap iron, hydrochloric
acid and chlorine is given in Figure 1.7 below:
Water
HCl
Scrap
iron
H2
Reactor
(Ferrous Chloride (FeCl2)
Spent liquor
Cl2(g)
Filtration
Sludge
Chlorination
FeCl3
Figure 1.7: Process diagram - production of FeCl3 based on scrap iron, HCl and chlorine
[CEFIC-INCOPA, 2004 #112]
1.4.2.3
Ferric chloride solution (spent FeCl2 liquor + chlorine)
Reaction:
FeCl2 + ½ Cl2 (g)
FeCl3
The spent liquor (FeCl2 + free HCl) recovered from different industries (for example: steel
industry, galvanising industry, wire industry, …) can be added to a reactor with iron to
neutralise free HCl (in case when the concentration of free HCl >1 %), and then oxidised to
ferric chloride by chlorine (see Figure 1.7 above) or, alternatively, directly converted into ferric
chloride by chlorination if the concentration of free HCl <1 % (see Figure 1.7 above).
A combination of processes described in Sections 1.4.2.1 and 1.4.2.2 above may also be used to
produce ferric chloride solution at a fixed concentration from spent acid (pickle liquor) of
varying concentrations.
1.4.2.4
Ferric chloride solution (iron ore + hydrochloric acid)
Reaction:
Fe2O3 + 6HCl
2FeCl3 + 3H2O
FeCl3 is prepared by the dissolution of iron ore (hematite containing Fe >70 %) in hydrochloric
acid (HCl >33 %). The reaction takes place at the temperature of 80 – 120 °C and under ambient
pressure, reaction time being 1 – 2 h.
A process flow diagram illustrating the production of FeCl3 based on iron ore and hydrochloric
acid is given in Figure 1.8 below:
14
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
Iron ore
HCl
REACTOR
Sludge
FILTRATION
FeCl3
Figure 1.8: Process diagram - production of FeCl3 based on iron ore and hydrochloric acid
[CEFIC-INCOPA, 2004 #112]
1.4.2.5
Ferric chloride solution (iron ore + hydrochloric acid + oxidation)
Reactions:
Dissolution of iron ore in hydrochloric acid:
Fe3O4 (Fe2O3 + FeO) + 8HCl
2FeCl3 + FeCl2 + 4H2O
Oxidation of ferrous chloride using chlorine, hydrogen peroxide, or sodium chlorate:
or
or
FeCl2 + ½ Cl2
FeCl2 + HCl + ½ H2O2
FeCl2 + ½ NaOCl3
FeCl3
FeCl3 + H2O
FeCl3 + ½ NaOCl
The iron ore (magnetite: 2/3 Fe2O3 + 1/3 FeO) is dissolved in a reactor with hydrochloric acid
(HCl >33 %) at the temperature of >80 °C, to obtain a mixture of ferric chloride and ferrous
chloride. In turn, this solution can be totally oxidised to form FeCl3 using Cl2 (g) or NaClO3 or
H2O2 as oxidants.
In the different processes (Sections 1.4.2.1, 1.4.2.2, 1.4.2.3, 1.4.2.5), chlorine – as the oxidation
agent – can be replaced with oxygen together with hydrochloric acid. In some cases, it then
gives a more diluted FeCl3 solution.
A process flow diagram illustrating the production of FeCl3 based on iron ore, hydrochloric acid
and oxidation is given in Figure 1.9 below:
15
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
Iron ore
HCl
REACTOR
2/3 FeCl 3 , 1/3 FeCl2
Sludge
FILTR ATION
Chlorination
tow er
Cl2 (g)
Oxydising
reactor
H 2 O 2 or NaClO 3
FeCl 3
Figure 1.9: Process diagram – production of FeCl3 based on iron ore and HCl and oxidation
[CEFIC-INCOPA, 2004 #112]
1.4.3
Current consumption and emission levels
Consumption and emission values in the production of ferrous chloride are given in Table 1.8:
Energy and water consumption
Energy consumption GJ/t product
0.012 to 0.3
Water consumption m3/t product
0.25 to 13
Emissions to air
Emission kg/t product
CO2
2 to 12
Hydrogen
0.73 to 13
Hydrogen chloride
0.0007 to 0.01
Emissions to water
Emission kg/t product
Iron
0.05 to 5
Zinc
0.005 to 1.5
Heavy metals
<0.0005 to 0.6
Waste to land
Waste kg/t product
Solid waste
5 to 35
Table 1.8: Consumption and emission values in the production of ferrous chloride
[CEFIC-INCOPA, 2004 #112]
1.4.4
Special features and limiting factors
There are no special features to be mentioned.
16
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on LVIC-S or by the European Commission, it is meant for information, only
1.4.5
Techniques to consider in the determination of BAT
Ferric chloride can be made by a variety of processes. This leads to a wide range of
environmental performances.
The process based on the use of spent acid (pickle liquor) and the process using iron ore are the
most common technologies.
In the case of ferric chloride, the variety of equipment used is limited as the processes are
generally simple. Therefore, within a particular process, the type and the technology of a
particular item of equipment (i.e a filter) can greatly affect the overall performance of the
process from an environmental point of view.
1.4.6
Emerging techniques
As filtration is used in almost every process, the equipment that minimises emissions to water
can be considered and, if possible, included in a new plant set-up.
The manufacturing of ferric chloride is exothermic, therefore heat recovery options can be
examined and, if possible, included in a new process scheme.
Emissions to air can be controlled via a scrubbing technique.
An area for future research and development would be the recycling of the hydrogen.
17
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
1.5
Potassium carbonate
Potassium carbonate (K2CO3) finds its major application in the speciality glass industry e.g. in
television screens where it performs better than glass made with soda ash [6, CEFIC, 2002].
Potassium carbonate is produced by reacting potassium hydroxide with carbon dioxide, as
follows:
2KOH + CO2
F
K2CO3 + H2O
It is shipped both as an aqueous solution, or it is crystallised and shipped as crystals.
Air emissions are due to the handling of solid materials. Water emissions are due to the water
evaporated during the crystallisation step. Waste generation is negligible [6, CEFIC, 2002].
Potassium carbonate (potash) was formerly produced by the ashing of wood and other raw
materials from plants. Since the middle of the XIX century, the saline residues from the rock
salt industry and salt deposits have been the raw materials used for the production of potassium
carbonate. Currently, the most important process is the carbonation of electrolytically produced
potassium hydroxide as described by the reaction above [48, W. Buchner et al, 1989].
Potassium hydroxide solutions (50 % KOH) are saturated with CO2, the solution is partially
eveporated and the potassium carbonate hydrate K2CO3.1.5 H2O which precipitates is separated
off. After drying, the product is either marketed as potash hydrate or is calcined in a rotary kiln
at temperatures of 250 to 350 ºC. Anhydrous potassium carbonate is also produced using a fluid
bed process, in which KOH is reacted with CO2 gas countercurrently in a fluidised bed reactor.
In Russia, potassium carbonate is also produced from deposits of alkali aluminosilicates (e.g.
nepheline) together with aluminium oxide, cement and sodium carbonate.
The main applications of potassium carbonate include [48, W. Buchner et al, 1989]:
•
•
•
•
•
•
•
glass manufacture (special glasses, crystal glass, CRT-tubes for TV)
soaps, detergents
enamels
food industry
pigment manufacture
other downstream K compounds (potassium hydrogen carbonate, potassium silicate)
synthesis of many organic chemicals and pharmaceutical products.
Since no information was submitted on potassium carbonate, therefore, the ‘Techniques to
consider in the determination of BAT’ relevant to the production of potassium carbonate could
not have been analysed in this document.
No further information provided.
18
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on LVIC-S or by the European Commission, it is meant for information, only
1.6
1.6.1
Sodium sulphate
General information
The production of natural sodium sulphate (like the production of natural NaCl or CaSO4) is
based on the extraction of a mineral with high content of sodium sulphate and its recovery in a
high purity grade through successive crystallisation/separation stages. This type of extractive
industry is not classified by the IPPC Directive and, therefore, it is not included in this
document. There are four producers of natural sodium sulphate in the EU-15, all of them located
in Spain and their emission values have not been included in this section.
1.6.1.1
Introduction
The world production of sodium sulphate (anhydrous or as Glauber’s salt – sodium sulphate
decahydrate Na2SO4.10H2O) was reported to be at the level of 4.2 million tonnes per year in
1985, out of which almost 50 % was produced from natural deposits [48, W. Buchner et al,
1989]. The production of pure sodium sulphate or Glauber’s salt from natural minerals such as
thenardite Na2SO4 or glauberite Na2SO4.CaSO4 is still important in Spain, Canada, the US,
Russia and China. Other production processes of sodium sulphate from salt lakes, salt brines
and potassium salt deposits (in this latter case via reaction of kieserite MgSO4.H2O with sodium
chloride NaCl), and in particular, sodium sulphate by-produced in large quantities in various
chemical and metallurgical processes are increasing [48, W. Buchner et al, 1989].
Sodium sulphate is a solid salt having wide range of applications in miscellaneous industrial
sectors like detergents, glass production or cellulose fibres [6, CEFIC, 2002]. Half of the
production is extracted from natural deposits while the remaining part is a by-product of other
industrial chemical processes, usually resulting from the neutralisation of excess sulphuric acid.
Therefore, the production of sodium sulphate may, in some places, exceed the commercial
demand, and processes have been developed to address this issue, using e.g. an electrochemical
decomposition route.
The direct production processes based on the reaction of solid sodium chloride with sulphuric
acid or sulphur dioxide/oxygen have become less important [EIPPCB, 2004-2005 #85].
Chemical processes like viscose-fibre spinning, ascorbic acid synthesis or sodium dichromate
production, deliver aqueous solutions of sodium sulphate which are, if necessary, concentrated,
and then directed to a crystallisation system which produces either directly anhydrous sodium
sulphate crystals or Glauber salt crystals (sodium sulphate decahydrate Na2SO4.10H2O) that are
further dehydrated. Electrolysis and electrodialysis processes intended to decompose sodium
sulphate into sulphuric acid and sodium hydroxide solutions, have been largely developed, but
their operational cost (e.g. the consumption of electricity) is an obstacle to their implementation.
Dust emissions to the atmosphere are the result of handling the solids. Water emissions include
dissolved salts.The generation of wastes is not an issue.
Organic contamination of air, water and wastes is to be considered, depending on the organic
process generating the sodium sulphate solution [6, CEFIC, 2002].
1.6.1.2
Basic data on sodium sulphate production
Sodium sulphate is a non toxic, hygroscopic white powder. It derives from natural deposits or is
recovered as a by-product from various industrial processes. Natural sodium sulphate is
extracted from sodium sulphate-rich brines or lakes, while the most common industrial sources
are the production of man-made fibres, hydrochloric acid, chromium chemicals, formic acid,
desulphurisation of flue-gases or lead battery recycling [64, CEFIC-SSPA, 2004].
19
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on LVIC-S or by the European Commission, it is meant for information, only
A major outlet for sodium sulphate is the detergent and cleaning agent industry, where their
free-flowing and preventive anti-caking properties are highly appreciated. Other significant end
uses are in the glass, textile, food and pharmaceutical industries.
The estimated world production of sodium sulphate is 6 million tonnes per year. Total capacity
is probably around 9 million tonnes. European production amounts to slightly more than
2 million tonnes and about half of the European production is from mining operations (natural
sodium sulphate). In Europe, approx. 40 producers of sodium sulphate can currently be
identified. Amongst them, four companies are located in Spain and produce natural sodium
sulphate by mining operations. The total European production of sodium sulphate is at the level
of approx. 2100 kt – see Table 1.9, however, no data have been submitted on the production
amounts originating from each of the mentioned process routes.
Sodium sulphate producing
countries/locations in Europe
FRANCE
Commentry, Roussillon, Loos
BELGIUM
Tessenderlo, Lommel
THE NETHERLANDS
Delfzijl
SPAIN
Toledo, Burgos, Madrid, Burgos,
Torrelavega, Almeria
PORTUGAL
Valongo-Porto
UNITED KINGDOM
Eaglescliffe, Dalry
GERMANY
Obernburg, Kelheim, Düsseldorf, Marl,
Milden Hütte, Schwedt
AUSTRIA
BMG, Lenzing, Glanzstoff Austria
ITALY
Bergamo, La Porto, Tonno
GREECE
Piraeus
FINLAND
Valkeakoski, Lappeenranta
SWEDEN
Perstorp
SWITZERLAND
Pratteln
POLAND
Alwernia, Gorzow
TURKEY
Alkim, Sisecam, Kaprasama
CZECH REPUBLIC
Lovosice
SLOVAKIA
Senica
SERBIA
Loznica
BULGARIA
Svistov
Origin/Estimated combined
production for Europe
Number
of plants
3
Methionine (2), Mannheim (1)
2
Mannheim (1), Viscose (1)
1
Messo (from Glauber’s salt) (1)
6
Natural (4), Viscose (1), Unknown origin (1)
1
Rayon (1)
2
Sodium dichromate (1), Ascorbic acid (1)
6
Rayon (2), Desulphurisation (1), Low grade – ex fibres
(1), Battery (1), Flue-gas desulphurisation (1)
3
Battery (1), Rayon (2)
3
Unknown origin (1), Pigments (2)
1
Natural (1)
2
Rayon (1), Unknown origin (1)
1
Formic acid (1)
1
Battery recycling
2
Sodium dichromate (1), Rayon (1)
3
Natural (1), Chromecake (2)
1
Rayon (1)
1
Rayon (1)
1
Rayon (1)
1
Rayon (1)
TOTAL EUROPE
41
Approx. 2100 kt
Notes: 1. Data estimation for non-CEFIC-SSPA Members, 2. For ‘natural’ production in Spain yearly capacities
were estimated instead of typical production volumes.
Table 1.9: Sodium sulphate production in Europe
[64, CEFIC-SSPA, 2004]
20
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on LVIC-S or by the European Commission, it is meant for information, only
According to most sources, the total sodium sulphate consumption in Europe is estimated at
1.6 million tonnes. Industry experts feel that overall consumption will remain stable or will
slightly decline over the next five years, with detergents remaining the dominant market.
In recent years, the capital investment in sodium sulphate production in Europe has decreased.
Some productions have been stopped among others in Italy, some plants have been
debottlenecked, but no new plants have been built.
1.6.2
Industrial processes used
Sodium sulphate is produced either from the mining of natural sodium sulphate or as a byproduct from various kinds of processes. As previously mentioned, mining process is not
included in this section.
The six major production processes covered are sodium sulphate as a by-product from:
•
•
•
•
•
•
fibres (rayon/viscose)
Messo process (from ‘Glauber’s salt’, the same as fibres)
chromium
Mannheim furnaces (HCl is considered the main product) [64, CEFIC-SSPA, 2004]
methionine
formic acid.
Of the above processes, the production of fibres is the dominating route for the production of
sodium sulphate as by-product in the EU.
Example plants most characteristic to the sodium sulphate recovery and production are:
•
•
•
viscose process – sodium sulphate plant in Lenzing, Austria
Mannheim furnace process – sodium sulphate plant of the Tessenderlo Group, Belgium
chromium process – sodium sulphate plant Elementis Chromium, Eaglescliffe, UK.
There is much less information available on the other process routes (ascorbic acid,
desulphurisation, battery recycling).
The starting materials for sodium sulphate depend on the main process, but in common to all
processes the production of sodium sulphate starts with Glauber’s salt (sodium sulphate
decahydrate Na2SO4.10H2O) or sodium sulphate in solution, which has to be separated from the
main product by, or followed by, crystallisation and drying. The different process steps can be
applied in a numerous of ways and with a large variety of equipment, which depend mainly on
the main production process used.
The different processes for producing sodium sulphate as a by-product, the variations within
each process and the varying raw materials, yield sodium sulphate with different purity, particle
size and contents of impurities.
1.6.2.1
Fibres process (Na2SO4 production from the viscose-fibre process)
Fibres are produced by spinning viscose in a sulphuric acid precipitation bath in which the
following reaction takes place – refer to the BREF for the Manufacture of Polymers (POL):
2 Cell–OCS2Na + H2SO4
2 Cell–OH + 2CS2 + Na2SO4
(Cell = cellulose)
21
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
A flow scheme of the production sodium sulphate from the viscose-fibre process is given in
Figure 1.10.
Fibre production process
Spinbath crystallization
NaOH
Steam
Water
Calcination
melting, dehydration
Vapour
Condensate
Water
Water
Centrifuge
Air
Steam/gas/
brine
Dryer / cooler
Filter
Exhaust air
Sieve
Na2SO4 product storage
Figure 1.10: Flow scheme of sodium sulphate production from the viscose-fibre process
[64, CEFIC-SSPA, 2004]
The raw material for the production of sodium sulphate is Glauber´s salt coming from spinbath
crystallisation as a by-product of the viscose fibre process according to the equation above.
The principle of the crystallisation process is to cool the spinbath from the production fibre to
<20 °C, causing Glauber's salt, Na2SO4.10 H2O, to crystallise. Glauber's salt is recovered by
centrifuging and is then calcined to form anhydrous sodium sulphate (thenardite). Glauber's salt
"melts" in its own water at 32.38 °C, forming a saturated solution of sodium sulphate that
contains anhydrous sodium sulphate as a solid phase in the melter. To neutralise the adherent
acid from the spinbath, caustic soda (NaOH) is added to control the pH. To remove the water,
evaporative crystallisation (dehydration) of the saturated sodium sulphate solution obtained on
melting Glauber's salt is used.
The consumption of energy is reduced by using multistage evaporation, in which the vapour
was employed as a heating steam for the following stage within the calcination and/or for other
heating purposes in the fibre process.
The separated solid sodium sulphate from the centrifuge is washed with water to improve its
quality and is dried by hot air, which is heated up with steam or natural gas and can hereafter be
cooled with dry cold air in a cooler.
The exhaust air is treated by a filter, and the residue is incorporated in the final product. The
final product is screened by sieves and stored in silos and bagged or shipped as bulk.
1.6.2.2
MESSO process (from Glauber’s salt)
In the Messo process, brine saturated with sodium sulphate is cooled in a number of steps. Due
to the cooling, the sodium sulphate crystallises as Glauber’s salt, and is a form of sodium
sulphate complexed with water molecules. The crystals are separated from the mother liquid
using centrifuges.
22
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on LVIC-S or by the European Commission, it is meant for information, only
To change the sodium sulphate into the anhydrous thenardite form, the separated crystals must
be suspended and heated with steam in a remelting vessel. Thus, the water leaves the sodium
sulphate crystals. The crystals are separated from the mother liquid using centrifuges. The
separated crystals are dried in a flash dryer and stored in different silos.
For reasons of efficiency, the mother liquid from the sodium sulphate centrifuges is cooled and
the additional crystallised Glauber’s salt is also brought to the remelting vessel. The primary
mother liquid and part of the secondary mother liquid are purged to effluent. Steam is produced
on the site using natural gas. The dryers are heated directly with natural gas.
A flow scheme of sodium sulphate production by the Messo process is shown in Figure 1.11.
Steam
Salt purge
Cooling
Purge
Remelting
Natural gas
Drying
Sodium sulphate
Recovery
Purge
Figure 1.11: Flow scheme of sodium sulphate production by the Messo process
[64, CEFIC-SSPA, 2004]
1.6.2.3
Chromium process
Crude sodium sulphate, a by-product from the sodium dichromate plant containing sexivalent
chromium compounds (Cr+6), is dissolved and transferred into treatment tanks. At this stage, the
solution is acidified in order to facilitate the chemical reduction of the solution using sulphur
dioxide. After reduction, the pH is raised leaving an insoluble species of chromium suspended
in a solution of sodium sulphate. This is filtered and the resulting solids are recycled back to the
primary process of the production of sodium dichromate. The purified sodium sulphate solution
goes forward subsequently into a crystalliser, centrifuge, dryer and classifier to form pure
sodium sulphate crystals. A flow scheme of the production of sodium sulphate from the
chromium process is given in Figure 1.12.
23
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
C austic s oda
S ulphur diox ide
C rude S odium
s ulphate from
evaporation plant
S ulphuric ac id
D is solv er
T reatm ent
tank s
C rystalliser
F ilter
C entrifuge
P rec ipitated s olids
Fine m aternal
returned to proc ess
Liquor rec yc led
to crys talliser
C las sifier
E x haus t gas es
P ure sodium
S ulphate to s ilos
A ir
D ryer
C yc lone
F uel
A ir
Figure 1.12: Flow scheme of the production of sodium sulphate from the chromium process
[64, CEFIC-SSPA, 2004]
1.6.2.4
Mannheim furnace process (hydrochloric acid)
As mentioned in Section 1.6.1, direct production processes based on the reaction of solid
sodium chloride with sulphuric acid or sulphur dioxide/oxygen, have become less important, as
– apart from the natural product – a by-product sodium sulphate from other processes is readily
available. However, in some locations synthetic sodium sulphate may be by-produced by the
Mannheim furnace process jointly with hydrochloric acid [64, CEFIC-SSPA, 2004].
Approximately two tonnes of 100 % Na2SO4 are produced per one tonne of 100 % HCl,
equivalent to approximately three tonnes of HCl solution which is in fact obtained in the
process. Hydrochloric acid is widely applicable in various industries, including the chemical,
tannery, textile, ceramic and pharmaceutical industries.
In the Mannheim furnace process, sulphuric acid reacts with sodium chloride producing sodium
sulphate and a 32 % hydrochloric acid solution obtained through absorption. Combustion gases,
obtained as intermediate products, are used to heat up the combustion air.
Producing sodium sulphate, that is free of sulphuric acid and hydrochloric acid, requires
equivalent amounts of acid (approx. 0.73 t of 100 % H2SO4 per tonne of Na2SO4) and salt
(approx. 0.83 t of 100 % NaCl per tonne of Na2SO4). The salt is measured out by means of a
screw, the quantity of acid is measured by flow. Based on raw material analyses, the quantity
ratio of the materials is then controlled by an operator.
The reaction between sulphuric acid and sodium chloride requires a long reaction time and a
high temperature. This is achieved in a muffle furnace with a hearth which is heated with
burners to approx. 600 °C. The air volume/oil ratio is kept constant. To prevent any problem of
exhaust gas after the HCl absorption, the air is not blown into the process.
24
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on LVIC-S or by the European Commission, it is meant for information, only
The hot air produced in the upper part of the Mannheim furnace (combustion chamber) is not in
contact with the lower part of the Mannheim furnace (reaction chamber). Indirect heating takes
place through a special wall. The HCl gases coming from the reaction in the lower part of the
furnace do not come into contact with the combustion gases in the upper part of the furnace. The
first stage of the reaction produces acidic sodium sulphate, or sodium hydrogen sulphate, which
then reacts with sodium chloride during the second stage to generate the end-product, sodium
sulphate.
Mechanical rakes rotate in the muffle furnace, pushing the sulphuric acid and sodium chloride
to the centre of the furnace and the produced sulphate to the outer edge. The hot, acidic, and
partly caked sodium sulphate is transferred through a conveyor belt to the subsequent treatment
operations of: grinding, cooling, stabilisation, and sieving.
The final product is of homogeneous quality, stored in a closed warehouse and sold in bulk form
or packed into 25 kg bags or 1000 kg big bags.
The basic chemical reaction governing the process is:
2NaCl + H2SO4 -
Na2SO4 + 2HCl
A flow scheme of the production of Na2SO4 by the Mannheim furnace process is given in
Figure 1.13.
S u lp h u ric a c id
S o d iu m c h lo r id e
W ATER
HCl
FUR N ACES
A B S O R P T IO N
N E U T R A L IS A T IO N
& C O N D IT IO N IN G
S o d iu m s u lp h a t e
H y d r o c h lo r ic a c id
Figure 1.13: Flow scheme of the production of Na2SO4 by the Mannheim furnace process
[64, CEFIC-SSPA, 2004]
1.6.2.5
Methionine process
Methionine synthesis leading to sodium sulphate production involves:
•
•
saponification with caustic soda
neutralisation with sulphuric acid.
25
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on LVIC-S or by the European Commission, it is meant for information, only
Sodium sulphate is recovered from the solution called “mother liquor” by concentration and
water evaporation in a multi-effects evaporator. With temperature increase and concentration,
sodium sulphate solubility decreases and leads to the precipitation of the sodium salt while
methionine remains in solution.
The solid phase is separated from the solution by decantation then filtration on a centrifuge in
which the cake is washed by water.
At the outlet of the centrifuge, sodium sulphate is dried in a hot air stream heated by steam.
Then the solid is separated from the gaseous phase by cyclone and sent by pneumatic transport
to the bulk storage silos from which it is loaded in bulk onto trucks to deliver to customers.
Downstream the dryer, airflow is cleaned in a scrubber supplied with process water to remove
thefine particles. During the drying, the humidity of sodium sulphate and the organic sulphur
compounds dissolved in the water, are transferred to the air. Before being released to the
atmosphere, the airflow is deodorised by contact with bleach in air-mix equipment in which a
chemical oxidation of the organic compounds is carried out.
Part of the production is purified in order to obtain a white coloured solid without odours.
The process treatment is performed in three steps:
•
•
•
humidification and spraying with sodium chlorate (NaClO3)
oxidation by calcination in a rotary kiln
cooling by air in a rotary mixer.
The off-gases from the calcination have to be purified before they can be released to the
atmosphere. In the first step, the solid particles are kept by a cyclone and recycled into the
process. The gaseous effluent is sent to a scrubber fed with water in order to eliminate residual
dust. The liquid waste only contains sulphate and chloride in such a low concentration that it
can be released to the environment.
A flow scheme of the production of sodium sulphate from the methionine process is given in
Figure 1.14.
26
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
Sodium
Calcination
on rotary kiln
Liquid
waste
Purified
sodium sulphate
Figure 1.14: Flow scheme of the production of sodium sulphate from the methionine process
[64, CEFIC-SSPA, 2004]
1.6.2.6
Formic acid process
In the formic acid process, sodium formate is chemically reacted with sulphuric acid in the
presence of formic acid. The solution from the reactor, containing formic acid and sodium
sulphate, is fed to a centrifuge where sodium sulphate crystals are separated from the solution.
The mother liquor is pumped into an evaporator where an additional amount of sodium sulphate
is crystallised. This step is followed by another centrifuging step.
The sodium sulphate crystals are sent to a multi-coil dryer heated by steam, followed by cooling
and sieving before the material is packed into bags or stored in bulk silos.
27
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on LVIC-S or by the European Commission, it is meant for information, only
The basic chemical equation governing this process is:
2Na – COOH + H2SO4
2HCOOH + Na2SO4
A flow scheme of the production of sodium sulphate in the formic acid process is given in
Figure 1.15.
Sodium formate
Sulphuric acid
Combustion gases
Reactor
Cooling water
Centrifuge
Evaporator
Formic acid
Condensate
Steam
Drier
Combustion gases
Air
Cooling water
Cooler
Cooling water
Sieve
Na
2
SO
4
Figure 1.15: Flow scheme of sodium sulphate production in the formic acid process
[64, CEFIC-SSPA, 2004]
1.6.3
Current emission and energy consumption levels
The current levels of emissions to air and water, as well as of emissions of solid residues and
energy consumption levels are briefly summarised in the following Tables. Aspects of key
environmental issues are also addressed.
Emissions to air are given in Table 1.10.
Process
Volume Cl2
exhaust gas
m3/t Na2SO4 kg/t
HCl
kg/t
All SSPA
except
natural
131 – 5000 0 – 0.0007 0 – 0.063
*No data available for some processes
SOx
NOx
NH3 CO2
Dust
kg/t
kg/t
kg/t
kg/t
0 – 1.1 0 – 0.46 0
kg/t
0 – 24 * 0.0003 – 0.66
Table 1.10: Sodium sulphate production – emissions to air (aggregated data: min – max)
[64, CEFIC-SSPA, 2004]
28
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on LVIC-S or by the European Commission, it is meant for information, only
Emissions to water are given in Table 1.11.
Volume of
Clwaste water
m3/t Na2SO4
kg/t
Process
All SSPA
except natural
0–5
kg/t
kg/t
kg/t
ppm
Suspended
matter
mg/l
0
0
0
0 – 60 *
0–5*
NO3- NH4+ F-
SO42kg/t
0 – 1.1 0.00006 – 20.0
COD
*No data available for some processes
Table 1.11: Sodium sulphate production – emissions to water (aggregated data: min – max)
[64, CEFIC-SSPA, 2004]
Emissions of solid residues are given in Table 1.12.
Solid waste
tonne/tonne Na2SO4
All SSPA
0 – 0.002
except natural
in total
Process
Nature of
residue
Contaminated salts
Various solid waste
Metals
Destination/
Re-use
Landfill
Landfill/Incineration
Recycling
Table 1.12: Sodium sulphate production – solid residues (aggregated data: min –max)
[64, CEFIC-SSPA, 2004]
Energy consumption in the production of sodium sulphate is given in Table 1.13.
Process
Electricity
kWh/t Na2SO4
All SSPA except natural
0.17 – 237
Others (coal, fuel, gas,
hydrogen, etc.)
kWh/t Na2SO4
0 – 1540
Total energy
consumption
kWh/t Na2SO4
120 – 1660
Table 1.13: Sodium sulphate production - energy consumption (aggregated data: min - max)
[64, CEFIC-SSPA, 2004]
Production of sodium sulphate as a by-product has a positive impact on the environment. All the
processes described in this section are treating a stream from its primary process and turning it
into a useful product (or by-product). It is a classic example of sustainable development where a
potential waste from one industry has useful applications in other fields.
1.6.4
Techniques to consider in the determination of BAT
Apart from being produced from naturally occurring sources (mining), sodium sulphate is
produced as a by-product from different chemical processes such as rayon production,
chromium chemicals, hydrochloric acid, methionine, and formic acid. As the sodium sulphate
derived from these chemical processes could be considered as a by-product, the six main
processes described in Section 1.6.2 have been taken into account when analysing techniques to
consider in the determination of BAT for the production of sodium sulphate. This is because all
of them – except the Mannheim furnace process, dedicated for the co-production of HCl as a
main product and sodium sulphate as a co-product – are, in principle, recovery processes and
their application in the industrial practice reduces the impact of several other industries on the
environment [64, CEFIC-SSPA, 2004], [EIPPCB, 2004-2005 #85].
29
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on LVIC-S or by the European Commission, it is meant for information, only
The production of sodium sulphate should itself be considered as a pollution control process, as
the waste stream would otherwise go to effluent [64, CEFIC-SSPA, 2004]. The quantity of the
sodium sulphate by-product depends on the production capabilities of the primary product and,
in principle, all these processes use Glauber’s salt as the raw material. The calcination of
Glauber’s salt, followed by the crystallisation and drying of the sodium sulphate always
depends on the individual layout and technical arrangements of the installations, as well as
linkages to various sources of energy. Pollution of the environment during the production of
sodium sulphate from Glauber’s salt is very low.
It should be noted, however, that the six main process routes for Na2SO4 production which have
been formerly described as ‘Techniques to consider in the determination of BAT’ in the LVIC-S
BREF section on sodium sulphate, have, in principle (with some exception regarding the
Mannheim process), the same environmental benefit (i.e. they use a by-product Na2SO4 which
otherwise would have to be discharged to waste waters). This means that they reduce the
environmental impact of the industries in which Na2SO4 is formed as a waste (or by-product)
stream.
They are, therefore, techniques to consider in the determination of BAT for the industries in
which Na2SO4 is formed as a waste stream. They do not reduce the emission and energy
consumption levels of the Na2SO4 production processes themselves (as given in the ‘Current
emission and energy consumption levels’ Section above) and, therefore, they are NOT
techniques to consider in the determination of BAT for the production of sodium sulphate.
As no clear BAT conclusions could be drawn for the production of sodium sulphate, it was
considered reasonable to remove the six ‘Techniques to consider in the determination of BAT’
from the BAT Reference Document on LVIC-S, and to move the whole section on sodium
sulphate from the BREF on LVIC-S to this “Additional Information submitted during the
information exchange on Large Volume Inorganic Chemicals – Solid and Others Industry”
document, which is associated with and closely related to the BREF on LVIC-S.
30
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on LVIC-S or by the European Commission, it is meant for information, only
1.7
Zinc chloride
Zinc chloride (ZnCl2) is one of several important members of the Zn-family of inorganic
compounds. The technological network of zinc chemical compounds, illustrating the linkages
among the Zn-family members (ZnCl2, ZnO and ZnSO4 among them) and major applications of
the Zn-based final products is shown in Figure 1.16, [83, UNIDO, 1988].
Zinc chloride is produced and shipped either as a 47 % solution in water or as an anhydrous
solid salt. Among its uses, wood preservation, electric batteries and minor applications in fibres
treatment, etc. should be mentioned [6, CEFIC, 2002].
Zinc chloride is produced by the reaction of a hydrochloric acid solution with zinc metal, zinc
scraps or zinc oxide. If needed, the solution leaving the reactor is freed from its heavy metals
contaminants by chemical reactions with an alkali or an alkali plus oxidant which results in their
precipitation under the form of hydroxide and are removed by filtration. When solid zinc
chloride is needed, this is obtained by further evaporation and cooling of the solution, until zinc
chloride crystallises [6, CEFIC, 2002].
Air dust emissions are due to the handling of the zinc chloride crystals and may include
particles. Water streams arise from the evaporation, and have traces of contaminants.
Generation of solid wastes is negligible [6, CEFIC, 2002].
H3PO4
Paint primer
Zn (H2PO4)2
Stearic acid
HCI
NaOH
ZnCl2
HNO3
Zn (OH)2
Redphosphor
Zn5P2
(O2)
Pure ZnO
Cadmium salts
H2S
Electrolysis
ZnSO4
H2O2
H2SO4
Rat poison
(C) and heat
O2
ZnO
Zn
H2SO4
Intermediate
Filler in rubber
Galvanising
Cellulose
Disinfectant
Textile
Textile
Catalyst
Ore Conc.
Zn
Ore Conc.
ZnCO3
Dryer
Stabiliser
Zn(NO3)2
CO2
Heat
C36H70O4Zn
ZnO2
Filler
Glass
Pigment
Enamel
Alloys
Coating
Medicine
Cosmetics
Herbicide
Galvanisation
Pigment
Disinfectant
Figure 1.16: Technological network of zinc chemical compounds
Based on [83, UNIDO, 1988]
No further information provided.
31
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on LVIC-S or by the European Commission, it is meant for information, only
1.8
Zinc sulphate
As submitted by CEFIC in April 2005
32
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on LVIC-S or by the European Commission, it is meant for information, only
1.9
Sodium bisulphate
As submitted by CEFIC in April 2005
33
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on LVIC-S or by the European Commission, it is meant for information, only
2 PURIFICATION OF NON-FERTILISER GRADE WET
PHOSPHORIC ACID (PARTIAL INFORMATION)
2.1
Inorganic Phosphates – Introduction
In order to bridge the information to Section 2.2 “Purification of non-fertiliser-grade wet
phosphoric acid – the options” below, it was considered reasonable to present here first key
information included in the introduction to Inorganic Phosphates, Chapter 6 of the BREF on
LVIC-S, as follows.
The application of inorganic phosphates as fertiliser is addressed in the BREF on Large Volume
Inorganic Chemicals – Ammonia, Acids and Fertilisers (LVIC – AAF), whereas the BREF on
Large Volume Inorganic Chemicals – Solid and others (LVIC-S) covers the production of
inorganic phosphates (refer to Chapter 6 of the BREF on LVIC-S).
In general terms, all inorganic phosphates can be seen as indirectly derived from phosphate
rock, Ca5(PO4)3F. The process from phosphate rock to final product may schematically be seen
to involve four major steps:
•
•
•
•
dissolution of phosphate from the rock to yield phosphoric acid
purification of phosphoric acid to a varying degree of purity
neutralisation of phosphoric acid by reaction with sodium, calcium, ammonium and/or
other ions to produce the required inorganic phosphate
dehydration, drying or calcination plus optional finishing to give a product in the required
form (eg. dry powder).
These steps may be carried out in one location, but quite commonly intermediate products are
used as the starting material for downstream steps. Therefore, when comparing several
production routes to manufacture a given inorganic phosphate product it is important to consider
the different strategies, process boundaries and starting points of the production.
Although strong mineral acids, such as sulphuric, hydrochloric and nitric acid are used for the
dissolution of the phosphate from the rock, by far the most commonly used is sulphuric acid.
Unpurified (merchant grade), usually called “green”, phosphoric acid is a market commodity
used by many producers as the starting point for further processing.
Invariably, the resulting phosphoric acid stream contains impurities originating from the
phosphate rock, including a number of metals and fluoride. For most applications, these
impurities need to be removed from the acid to obtain a certain level of purity of the product.
The required level of purity is largely determined by the final use of the phosphoric acid
product.
In some cases, the purification takes place in a dedicated plant by employing solvent extraction,
this leading to the production of a high quality phosphoric acid. Optionally, additional
techniques (for removal of arsenic, sulphate or fluoride) may be applied.
Depending on the required degree of purity of the final product, this can provide a feedstock for
the production of detergent, animal feed or human food phosphates.
Consequently, the purification of ‘green’ phosphoric acid may be quite shallow (e.g. ‘green’
acid pretreatment, virtually by desulphation only) or deep (concentration, desulphation, fluoride
and arsenic removal, and the purification of the ‘green’ acid by solvent extraction in a number
of steps – not necessarily in this order).
1
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
In other cases (for instance in some of the sites producing detergent phosphates), the
purification (starting from unpurified “green”, merchant commodity phosphoric acid) takes
place in the same process as the production of a given inorganic phosphate.
Phosphoric acids of various degrees of purity are available as global merchant commodities or,
in some cases, can be produced at the same site where both acid purification installations and
inorganic phosphate production plants are situated. Operators will purchase purified acid of the
degree of purity required for the range of inorganic phosphates they are manufacturing, or will
purify phosphoric acid onsite to the degree of purity required in downstream operations.
Depending on the purity of the acid used, some sites can manufacture inorganic phosphates for
different applications (detergent, animal feed, food).
A high purity phosphoric acid may also be obtained by the thermal route. White phosphorus,
derived by thermal reduction from phosphate rock or other phosphate sources, is combusted in
air, followed by the absorption of phosphorus pentoxide (P2O5) in water (refer to the BREF on
LVIC-AAF).
In general, this process route is seldom used in Western Europe for the production of detergentgrade STPP or for the production of inorganic feed phosphates, as the phosphoric acid produced
from elemental phosphorus is of a high purity, not required for detergent or animal feed
applications.
Some inorganic phosphate products have a range of uses which require different levels of
purity: for example STPP, which is used in detergents and cleaning products, but also as a
human food and pharmaceutical ingredient which requires higher grades of purity.
In some cases, the same installation can be used to manufacture an inorganic phosphate product
for various purposes; different quality grades being achieved by using different quality
feedstocks (phosphoric acid or phosphate rock of different levels or purity) and/or by additional
purification steps operated optionally within the production process.
The purification of phosphoric acid has not been described in the BREF on LVIC-AAF as, for
most fertiliser production processes, such a step is not necessary.
Also, data and information on the purification of phosphoric acid have not been submitted
during information exchange on the BREF on LVIC-S and, therefore, detailed information on
consumption and emission levels from the phosphoric acid purification step is not available.
As the description of processes and unit operations applied in the purification of non fertiliser
grade wet phosphoric acid was not covered in detail either in the BREF on LVIC-AAF or in the
BREF on LVIC-S, there is, therefore, a clear information gap in this area between the two large
volume inorganic chemical industry BREFs.
In order not to loose partial information from the BREF on LVIC-S (Chapter 6), it was
considered important to include in this document one of the “Techniques to consider in the
determination of BAT” (deleted from the BREF on LVIC-S upon the recommendation of the
TWG on LVIC-S), as it may be of value in future for the revision of one of the LVIC BREFs
and information exchange on the routes available for the purification of “green” phosphoric
acid, either by a chemical process or a physical process (solvent extraction).
It should be noted that as the purification of the phosphoric acid, typically (but not always) takes
place upstream of the site of the inorganic phosphates plants, therefore, in most cases (but not
always), the main environmental benefits are outside of the scope of the feed phosphates sector.
2
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on LVIC-S or by the European Commission, it is meant for information, only
2.2
Purification of non-fertiliser grade wet phosphoric acid –
the options
Description
Since, in most cases, the purified non-fertiliser-grade wet phosphoric acid is selected for the
production of inorganic phosphates, the techniques available for the purification of “green”
phosphoric acid (to remove sulphate, arsenic, fluoride and other impurities) need to be analysed
and compared in detail from the technical, economical, and environmental point of view in
order to reduce the impact of the production of feed-phosphates on the environment in the
whole chain of operations, starting from the intermediate phosphoric acid product and ending at
the final food-grade phosphate product.
Such a comparison needs to be carried out for two typical cases A and B pertaining to the plant
location, and for two alternative process routes X and Y available to achieve the different degree
(depth) of purification of “green” phosphoric acid:
•
•
A. Phosphoric acid purification at the wet phosphoric acid production site, typically (but not
always) outside of the inorganic phosphates production site
B. Phosphoric acid purification at the inorganic phosphates production site (in some cases it
may also be the site of the phosphoric acid plant),
and
•
•
X. Desulphation (adding lime), neutralisation (adding NaOH/Na2CO3) and purification by
precipitation, involving various techniques available for chemical purification of the wet
phosphoric acid, dependent on the required degree of acid quality
Y. Concentration, desulphation, and very deep purification of the wet phosphoric acid by
solvent extraction, involving more elaborate physico-chemical techniques.
Wet process phosphoric acid is purified by numerous methods and to a wide variety of
standards depending on the further application of the acid.
The most basic method, and the one which all suppliers of merchant-grade acid carry out before
shipment, is clarification, by settling or other mechanical means, to remove suspended solids. In
case the acid is used for the production of fertilisers no further treatment is usually applied.
Chemical purification methods can be employed if the acid is to be used for specific purposes,
not requiring a high quality. Active carbon treatment is the usual means of removing organic
impurities. Fluorine is removed by adding reactive silica and distilling off silicon tetrafluoride.
Phosphate rock or lime may be added to the impure acid to remove excess sulphate. Metals ions
can be selectively precipitated by various chemicals. By adding a Na2S solution to the acid,
arsenic can be precipitated as arsenic sulphide. Removal of other cationic impurities, especially
Fe, Al, Mg and Ca, can be achieved by neutralising the acid with sodium carbonate or caustic
soda. The phosphoric acid in this process is converted to a phosphate salt solution.
More elaborate techniques involving (organic) solvent treatment are used to obtain purer acid
such as that required for animal feed supplements (mainly cadmium removal) and especially the
food industry. Liquid/liquid extraction processes are most commonly used. Processes are
operated for the separation of single components (e.g. uranium and cadmium) as well as of
practically all impurities in wet phosphoric acid. The quality of such purified acid nearly equals
that of thermally produced acid. Besides liquid/liquid extraction processes, precipitation
processes are also being employed.
3
This document has not been fully peer reviewed and the information within is not validated nor endorsed by the TWG
on LVIC-S or by the European Commission, it is meant for information, only
Achieved environmental benefits
The selection of both the location (option A vs. B) and the route for the purification of nonfertiliser grade wet phosphoric acid (option X vs. Y) may benefit in the minimisation of the
impact of the production of inorganic phosphates on the environment.
Optimum solutions can be selected with regard to the usage of raw materials, energy sources,
the recycling of by-products, and waste utilisation, including the advantage of the economy of
scale in order to reduce the impact of the production of inorganic phosphates on the
environment in the whole chain of operations, starting from the intermediate phosphoric acid
product and ending at the final feed, food, and detergent-grade phosphate product.
Cross-media effects
To be analysed in detail for the location (option A vs. B) and the route for the purification of
non-fertiliser grade wet phosphoric acid (option X vs. Y).
Operational data
No detailed data available, as typically (but not always) the purification of the acid takes place
upstream of the inorganic phosphate process. Moreover, specific data and information on more
elaborate techniques for the purification of wet phosphoric acid are, to a certain degree, subject
to confidentiality.
Applicability
To varying degrees, applicable to the plants producing feed, food and detergent-grade
phosphates by the phosphoric acid route, depending on the long-term strategies set for the
supply of phosphoric acid and the manufacture of final feed phosphate products.
Driving force for implementation
Reduced impact on the environment in the whole chain of operations, beginning with the
intermediate phosphoric acid product and ending with feed, food and detergent-grade phosphate
product. Reduction of the manufacturing cost. Product quality improvement.
Example plants
Food and detergent-grade phosphate plant in Huelva, Spain (based on purified wet phosphoric
acid). Food and detergent-grade phosphate plant in Engis, Belgium (based on purified wet
phosphoric acid). Feed-grade phosphate plants in the EU based on the supplies of purified wet
phosphoric acid from outside of the feed phosphate production sites.
Reference literature
[65, CEFIC-IFP, 2004], [84, A. Davister, 1981], [85, EIPPCB, 2004-2005], [93, CEFIC-CEEP,
2004], [101, RIZA, 2000], [102, UNIDO, 1980].
4
References
REFERENCES
6
CEFIC (2002). "IPPC BAT Reference Document, Best Available Techniques for
Producing Large Volume Solid Inorganic Chemicals - Generic Part".
8
CEFIC (2004). "CEFIC Chemistry Sectors".
9
CEFIC (2004). "The European chemical industry in a worldwide perspective - Facts and
Figures 2004".
11
The Council of the EU (1996). "Council Directive 96/61/EC of 24 September 1996
concerning integrated pollution prevention and control".
12
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EPER".
13
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14
EIPPCB, S., Spain (2003). "Meeting Report of 23 September 2003 - Record of the
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20
CEFIC-TDMA (2004). "Process BREF Titanium Dioxide Background Document".
21
The Council of the EU (1992). "Council Directive 92/112/EEC on procedures for
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22
Euratom (1996). "European Directive 96/29/EEC".
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24
Tioxide Group Ltd (1995). "Synopsis "Making Better Choices - How Tioxide uses Life
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25
D.G. Heath (1996). ""A Life Cycle inventory comparison of process and feedstock
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26
EIPPCB (2003). "Mission Report - Visits of two sites in the UK for the production of
TiO2 according to chloride route - Greatham and sulphate route - Grimsby".
27
N.L. Glinka (1981). "Problems and Exercises in General Chemistry".
28
UNIDO (1982). "A Programme for the Industrial Development Decade for Africa".
31
R. N. Shreve (1945). "The Chemical Process Industries", Chemical Engineering Series.
33
CEFIC-ESAPA (2004). "IPPCB BAT Reference Document Large Volume Solid
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39
S. Leszczynski et al (1978). "Soda i produkty towarzyszace".
40
CEFIC-ESAPA (2003). "IPPCB BAT Reference Document Large Volume Solid
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5
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41
Solvay S.A. (2003). "Process BREF for Soda Ash - Presentation".
42
UBA-Germany (2001). "German Notes on BAT for the production of LVSIC
Titanium Dioxide".
43
UBA - Germany (2001). "German Notes on BAT for the production of LVSIC Sodium Silicate".
44
UBA - Germany (2001). "German Notes on BAT for the production of LVSIC Sodium Perborate".
45
UBA - Germany (2001). "German Notes on BAT for the production of LVSIC - Soda".
46
CEFIC-TDMA (2001). "Process BREF Titanium Dioxide Background Document".
47
InfoMil (2002). "Dutch Notes on BAT for the Carbon Black industry", ISBN 90-7632307-0.
48
W. Buchner et al (1989). "Industrial Inorganic Chemistry", 3-527-26629-1.
49
CEFIC-ASASP (2002). "BREF Working Group - Synthetic Amorphous Silica".
50
CEFIC-INCOPA (2004). "Mini-Process BREF for Aluminium Sulphate".
53
EIPPCB (2004). "Mission Report - Visit of Soda Ash production plant site in
Torrelavega, Santander, Cantabria, Spain".
54
EIPPCB (2004). "Mission Report - Carbon Black - Visits of two sites in Botlek and
Rozenburg, Rotterdam area, the Netherlands".
56
InfoMil (2004). "Dutch Fact sheet on Magnesium compounds".
57
CEFIC-PEROXYGENES (2004). "Process BREF - Sodium Percarbonate".
58
CEFIC ZEAD-ZEODET (2004). "Mini-BREF Synthetic Zeolites for LVIC-S".
59
CEFIC-TDMA (2004). "Mini-Process BREF for Copperas and Related Products".
60
UBA-Austria (2004). "Mini BREF Calcium Carbide".
61
Entec UK Limited (2004). "Mini-BREF for Sodium Sulphite and related products".
62
CEFIC-ZOPA (2004). "Mini-BREF Zinc Oxide Production".
63
CEFIC-PEROXYGENES PERBORATE Sub Group (2004). "Process BREF Sodium
Perborate".
64
CEFIC-SSPA (2004). "Mini-BREF Sodium Sulphate Production".
65
CEFIC-IFP (2004). "BRF LVIC-S Inorganic Feed Phosphates".
66
CEFIC-Sodium Chlorate (2004). "Mini-process BREF for Sodium Chlorate".
67
InfoMil - Dutch Authorities (2004). "Factsheet on Production of Silicon Carbide".
68
Norwegian Pollution Control Authority (2003). "BAT for Al fluoride production".
6
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References
69
Environment Agency (1999). "Processes Subject to Integrated Pollution Control Inorganic Chemicals", S2 4.04.
70
Environment Agency (1999). "Processes Subject to Integrated Pollution Control Inorganic Acids and Halogens", S2 4.03.
71
CITEPA (1997). "Best Available Techniques for the Chemical industry in Europe Workshop on 14-16 May 1997 in Paris".
73
G.V. Ellis (1979). "Energy Conservation in a Large Chemical Company", Proceedings
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75
J. A. Lee (1985). "The Environment, Public Health and Human Ecology - a World Bank
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76
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78
World Bank (1991). "Environmental Assessment Sourcebook - Volume III", World
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79
BIPROKWAS (1985-1995). "Bid Letters for Inorganic Chemicals", 511.171-TR-XYZ.
82
UNIDO (1988). "Study on the Manufacture of Industrial Chemicals in the Member
States of SADCC - Part II Inorganic Industry", DP/RAF/86/013.
83
UNIDO (1988). "Study on the Manufacture of Industrial Chemicals in the Member
States of SADCC - Part IV, Annex XII - Utilization of Chemical Metals, Minerals and
Wastes", DP/RAF/86/013.
84
A. Davister, G. M. (1981). "From Wet Crude Phosphoric Acid to High Purity
Products", Proceedings No. 201.
85
EIPPCB, C., MS, (2004). "Process BREFs, Mini-BREFs, Presentations, Papers, Notes
and Documents concerning the BREF on LVIC-S".
86
The Council of the EU (2004). "Council Directive 2004/8/EC of 11 February 2004 on
the promotion of cogeneration based on a useful heat demand in the internal energy
market".
87
Ullmann's (2001). "Ullmann's Encyclopedia of Industrial Chemistry".
88
UBA - Germany (2004). "Mini-BREF on the Production of Carbon Disulphide".
89
CEFIC-INCOPA (2004). "Mini-Process BREFs for Polyaluminium Chloride,
Aluminium Chloride".
90
CEFIC-INCOPA (2004). "Mini-Process BREF Ferrous Chloride".
91
Takuji Miyata (1983). “Soda ash production in Japan and the new Asahi process",
Chemistry and Industry, pp. 4.
92
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Ref: UC 4011.
93
CEFIC-CEEP (2004). "CEEP STPP BREF (BAT)".
94
CEFIC-SOLVAY S.A. (2004). "Process BREF for Precipitated Calcium Carbonate".
7
References
95
CEFIC-Brunner Mond (2004). "Process BREF for Calcium Chloride".
96
CEFIC-ELOA (2004). "BAT Notes for the Production of Lead Oxide".
97
The Council of the EU (2004). "Regulation (EC) No 648/2004 of the European
Parliament and the Council of 31 March 2004 on detergents".
98
CEFIC (2003). "CEFIC Note No. 295 - Criteria for the selection between LVIC and
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99
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100
Environment Agency (2004). "Guidance for the Inorganic Chemicals sector IPPC
S4.03", Draft 1.1.
101
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102
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No. 13.
8
Glossary
GLOSSARY OF TERMS AND ABBREVIATIONS
Abbreviations commonly used in this document
BAT
BL
BOD
BREF
CAS
CFC
CHP
COD
DBM
DC
DCP
ELV
EMS
EOP
EPER
ESP
EURO
FCCR
FSA
GDP
GHG
HEPA
HHV
HM
HP
IPPC
LCA
LHV
LP
LPG
LVIC-S
MAP
MCP
MDCP
MSP
NA
NeR
PAHs
PI
PCC
ROI
R&TD
SCR
SNCR
Best Available Techniques
Battery Limits
Biochemical oxygen demand: the quantity of dissolved oxygen required by
micro-organisms in order to decompose organic matter. The unit of
measurement is mg O2/l. In Europe, BOD is usually measured after 3 (BOD3), 5
(BOD5) or 7 (BOD7) days.
BAT reference document
Chemical Abstract Service
Chlorofluorocarbon
Co-generation of Heat and Power
Chemical oxygen demand: the amount of potassium dichromate, expressed as
oxygen, required to chemically oxidize at ca. 150 °C substances contained in
waste water.
Dead Burned Magnesia
Direct Current
Dicalcium Phosphate
Emission limit values: the mass, expressed in terms of certain specific
parameters, concentration and/or level of an emission, which may not be
exceeded during one or more periods of time.
Environmental Management System
End-of-pipe
European Pollutant Emission Register
Electrostatic precipitator
European currency unit
Fluid Catalytic Cracker Residue
Fluosilicic Acid
Gross Domestic Product
Greenhouse gases
High-efficiency Particulate Arresters
High Heating Value
Heavy Metals
High Pressure
Integrated Pollution Prevention and Control
Life Cycle Assessment
Low Heating Value
Low Pressure
Liquefied Petroleum Gas
Large Volume Inorganic Chemicals – Solid and Others
Monoamonium Phosphate
Monocalcium Phosphate
Monodicalcium Phosphate
Monosodium Phosphate
New Asahi soda ash process
Netherlands emission Regulations
Polyaromatic hydrocarbons
Process-integrated
Precipitated Calcium Carbonate
Return on Investment
Research and Technical Development
Selective Catalytic Reduction
Selective Non-Catalytic Reduction
9
Glossary
SS
STPP
TOE
VOC
WR
WWTP
Suspended Solids (content) (in water)
Sodium Tripolyphosphate
Tonne of Oil Equivalent
Volatile Organic Compounds
Weight Ratio
Waste water Treatment Plant
Abbreviations used for the organisations and countries quoted in this document
ASASP
BSI
CEEP
CEES
CEFIC
CITEPA
EA
EC
EIPPCB
EFMA
EFPA
ELOA
ENTEC
EPPAA
ESAPA
EU
EU-15
EU-25
HT
ICBA
INCOPA
IEF
InfoMil
IFP
IPTS
ISO
NGOs
SFT
SSPA
TDMA
TWG
UNIDO
US EPA
UBA
UBA-Austria
US
VROM
ZEAD
ZEODET
ZOPA
10
Association of Synthetic Amorphous Silica Producers
British Standard Institute
Centre Européen d’Etudes des Polyphosphates
Centre Européen d’Etudes des Silicates
European Chemical Industry Council
Centre Interprofessionnel Technique D’Etudes de la Pollution Atmospherique
Environment Agency
European Commission
European Integrated Pollution Prevention and Control Bureau
European Fertilisers Manufacturers Association
European Food Phosphate Producers Association
European Lead Oxide Association
Entec UK Limited
European Pure Phosphoric Acid Producers Association
European Soda Ash Producers Association
European Union
European Union (15 Member States)
European Union (25 Member States, including 10 new Member States)
Huntsman Tioxide
International Carbon Black Association
Inorganic Coagulants Producers Association
Information Exchange Forum (informal consultation body in the framework of
the IPPC Directive)
The Dutch Information Centre for Environmental Licensing
Inorganic Feed Phosphates
Institute for Prospective Technological Studies
International Standards Organisation
Non-Governmental Organisations
Norwegian Pollution Control Authority
Sodium Sulphate Producers Association
Titanium Dioxide Manufacturers Association
Technical Working Groups
United Nations Industrial Development Organization
U.S. Environmental Protection Agency
Umweltbundesamt (Federal Environmental Agency - Germany)
Umweltbundesamt (Federal Environment Agency - Austria)
United States of America
Dutch Ministry of Housing, Spatial Planning and Environment
Zeolite Adsorbents
Association of Detergent Zeolite Producers
Zinc Oxide Producers Association
Glossary
Abbreviations of units of measure
bar
°C
g
h
J
K
kg
kPa
kt
kWh
l
m
m2
m3
mg
Nm3
pH
ppb
ppm
ppmv
s
t
vol-%
W
bar (1 bar = 100 kPa, 1.013 bar = 1 atm)
degree Celsius
gram
hour
Joule
Kelvin (0 °C = 273.15 K)
kilogram (1 kg = 1000 g)
kilo Pascal
thousand tonnes
kilowatt-hour (1 kWh = 3600 kJ = 3.6 MJ)
litre
metre
square metre
cubic metre
milligram (1 mg = 10-3 gram)
Normalised m3 (gas, 273 K, 101.3 kPa)
scale for measuring acidity or alkalinity
parts per billion
parts per million
parts per million (by weight)
second
metric tonne (1000 kg or 106 gram)
percentage by volume
Watt (1 W = 1 J/s)
Prefixes
n
b
m
c
k
M
G
nano 10-9
micro 10-6
milli 10-3
centi 10-2
kilo 103
mega 106
giga 109
Chemical formula commonly used in this document
(refer also to Annex 1 – Basic classes of inorganic compounds)
Al
AlCl3
AlF3
AlNaO2
Al2O3
Al(OH)3
Al2(SO4)3
Alx(OH)yClz
Alx(OH)yClz(SO4)q
As
Ba
BaCl2
B
C
Ca
Aluminium
Aluminium chloride
Aluminium fluoride
Sodium aluminate
Aluminium oxide
Aluminium hydroxide
Aluminium sulphate
Aluminium hydroxy chloride
Aluminium hydroxy chloride sulphate
Arsenic
Barium
Barium chloride
Boron
Carbon
Calcium
11
Glossary
Ca2+
CaC2
CaCl2
CaF2
CaCO3
CaCO3.MgCO3
CaO
Ca(OH)2
CaHPO4
Ca3(PO4)2
CaSO3
CaSO4
Cd
CH4
CxHy
C2H6
C2H4
C2H2
ClCl2
ClOClO3CNCo
CO
CO2
CO32-COS
Cr
Cr3+/Cr6+
CrO
CS2
Cu
CuO
CuSO4
F
FFe
Fe2+
Fe3+
FeCl2
FeCl3
FeClSO4
FeO
Fe2O3
FeO.TiO2
FeSO4
FeSO4.H2O
FeSO4.7H2O
Fe2(SO4)3
H2
HCl
HClO
HCN
HCOOH
HCO3Hg
12
Calcium ion
Calcium carbide
Calcium chloride
Calcium fluoride (flourspar)
Calcium carbonate (limestone)
Dolomite
Calcium oxide
Calcium hydroxide
Dicalcium phosphate
Calcium phosphate
Calcium sulphite
Calcium sulphate
Cadmium
Methane
Hydrocarbons
Ethane
Ethene
Acetylene
Chloride
Chlorine
Hypochlorite
Chlorate
Cyanide
Cobalt
Carbon monoxide
Carbon dioxide
Carbonate
Carbonyl sulphide
Chromium
Chromic ions
Chromium oxide
Carbon disulphide
Copper
Copper oxide
Copper sulphate
Fluorine
Fluoride
Iron
Ferrous ion
Ferric ion
Ferrous chloride
Ferric chloride
Iron chloro sulphate
Iron (II) oxide
Iron (III) oxide
Ilmenite
Ferrous sulphate
Ferrous sulphate monohydrate
Ferrous sulphate heptahydrate (copperas)
Ferric sulphate
Hydrogen
Hydrogen chloride
Hypochlorous acid
Hydrogen cyanide
Formica acid
Bicarbonate
Mercury
Glossary
HF
H2O
H2O2
HNO2
HNO3
H3PO4
H2S
H2SO4
H2SiF6
K
KCl
KClO3
K2CO3
KOH
Mg
Mg2+
MgCl2
MgCO3
MgO
Mg(OH)2
MgSO4
Mn
Na
Na+
NaBO3.H2O
Na2B4O7.5H2O
NaCl
NaClO
NaClO3
Na2CO3
Na2CO3.1.5H2O2
Na2Cr2O7
NaHCO3
NaH2PO4
Na2HPO4
NaNO2
NaNO3
Na2O
NaOH
NaHSO3
Na2SO3
NaHSO4
Na2SO4
Na2SO4. 10H2O
Na2S2O3
Na2S2O5
Na5P3O10
Na2S
Nax(AlO2)y(SiO2)z
N2
NH3
NH4+
NH4OH
NH4Cl
NH4HCO3
(NH4)2CO3
NH4HSO4
Hydrogen fluoride
Water
Hydrogen peroxide
Nitrous acid
Nitric acid
Phosphoric acid
Hydrogen sulphide
Sulphuric acid
Flousilicic acid
Potassium
Potassium chloride
Potassium chlorate
Potassium carbonate
Potassium hydroxide
Magnesium
Magnesium ion
Magnesium chloride
Magnesium carbonate
Magnesium oxide
Magnesium hydroxide
Magnesium sulphate
Manganese
Sodium
Sodium ion
Sodium perborate monohydrate
Borax
Sodium chloride
Sodium hypochlorite
Sodium chlorate
Sodium carbonate
Sodium percarbonate
Sodium dichromate
Sodium bicarbonate
Monosodium phosphate
Disodium phosphate
Sodium nitrite
Sodium nitrate
Sodium oxide
Sodium hydroxide
Sodium hydrogensulphite (sodium bisulphite)
Sodium sulphite
Sodium hydrogensulphate (sodium bisulphate)
Sodium sulphate
Sodium sulphate decahydrate (Glauber’s salt)
Sodium thiosulphate
Sodium metabisulphite
Sodium tripolyphosphate
Sodium sulphide
Zeolite
Nitrogen
Ammonia
Ammonium ion
Ammonium hydroxide
Ammonium chloride
Ammonium bicarbonate
Ammonium carbonate
Ammonium bisulphate
13
Glossary
(NH4)2SO4
Ni
NO
NO2
NO3NOx
O2
OClOHP
P2O5
Pb
PbO
Pb3O4
R-NH2
S
S2SO2
SO3
S2O32SO32SO42SOx
Si
SiC
SiO2
n(SiO2).Na2O
Ti
TiO2
TiO(OH)2
TiOSO4
TiCl4
V
VOCl
W
Zn
ZnCl2
ZnCO3
ZnO
ZnS
ZnSO4
14
Ammonium sulphate
Nickel
Nitrogen monoxide
Nitrogen dioxide
Nitrate
Nitrogen oxides
Oxygen
Hypochlorite
Hydroxide
Phosphorus
Phosphorus pentoxide
Lead
Lead oxide (litharge)
Lead oxide (red lead)
Amine
Sulphur
Sulphide
Sulphur dioxide
Sulphur trioxide
Thiosulphate
Sulphite
Sulphate
Sulphur oxides
Silicon
Silicon carbide
Silica
Sodium silicate
Titanium
Titanium dioxide
Titanyl hydroxide
Titanyl sulphate
Titanium tetrachloride
Vanadium
Vanadium oxychloride
Tungsten
Zinc
Zinc chloride
Zinc carbonate
Zinc oxide
Zinc sulphide
Zinc sulphate