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INTERNATIONAL LABOUR
ORGANIZATION
Sectoral Activities Programme
SAP 2.76/WP.130
SECTORAL ACTIVITIES PROGRAMME
Industrial Activities Branch
Working Paper
Small-scale gold mining:
Examples from Bolivia, Philippines & Zimbabwe
Edited by Norman S. Jennings
3. The Button gold mine, Zimbabwe
John Hollaway (6)
Abstract
The Button Mine is a small underground gold operation that has been worked as a sequence of pits over
the past five years. It is typical of many hundreds of small-scale mines in Zimbabwe, producing about 240
tonnes of ore a year and recovering about 1 kilogram a year of gold from this ore. Despite the mine being
legally registered, it operates largely outside the formal sector.
The mine employs between three and seven workers, including one experienced miner with a blasting
licence. These employees live and work under crude, often unhealthy, conditions.
The nearby Shamva Mining Centre (7) of the Intermediate Technology Development Group (ITDG)
provides some training and provides the Button Mine with drilling and blasting services. Its mill is used to
recover the gold from the ore. There is evidence that the mine has significant resources at fairly shallow
depth but no attempt has been made to develop the deposit beyond the artisanal stage.
This study concludes that the operation is representative of a large number of such mines in Zimbabwe
which have considerable potential, but are seen by the current claim holders as an unattractive investment
because of the considerable capital needed. Technology does not present a real constraint; the necessary
equipment and skills are available locally; nor are there legal obstacles. The Zimbabwe mining law is
probably the simplest in Africa for the acquisition of full, transferable mineral title. Rather it is the shortage
of risk capital and entrepreneurial skills that inhibit the development of small-scale mining.
In the past, the white community largely supplied these essentials, but since Independence in 1980 this
source has dwindled. Although two NGOs are working in this area (ITDG and the Foundation for Small
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Mines), they have limited resources and the speculative nature of small-scale mining does not sit
comfortably with the nature of development assistance. There is a need, therefore, to draw the attention
of the new business and professional elites that have arisen to the opportunities for growth that small-scale
mines like the Button Mine present. If this is done, there will be numerous new employment opportunities
in small mines -- in a healthier, safer and more prosperous environments than in the present crude
operations.
Introduction
Zimbabwe has probably the most diverse mining sector in Africa, both in terms of mines and the range of
minerals produced. In 1997 over 35 metals and minerals were produced, and over the years several
thousand deposits have been exploited. However, consistent output is normally recorded from about four
hundred regular mining operations.
The Button Mine is typical of the more than 5,000 small-scale mines in Zimbabwe (8). The mine is situated
in the hills of the Mazowe river valley about 100 km north of Harare (figure 1). The owner, Mr O.T.
Manjengwa, mines via an adit and treats ore at a custom mill, The Shamva Mining Centre (SMC) is 12
km away. The level of technology used is very low and, as a consequence, the three adjacent blocks of
claims in which the mine has been developed (an area of 200x1,500 metres) are pockmarked with pits,
adits and trenches.
Figure 1. Button mine location
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The owner has had no training in mining, being employed for a number of years in a department store in
Bulawayo. He left this employment about 14 years ago and with his savings bought a business in the
Wedza area, about 70 km east of Harare. Here he prospered as a butchery and bottle store owner.
Wedza is a mining area, and many of his customers were miners who proffered gold rather than cash as
payment for goods. He became a gold buyer for local miners using a claim block registered in his name as
the ostensible source of the bullion, and so acquired an interest in gold mining. He acquired the three
Button Mine claims in 1986 and began to mine outcrops and other mineralized areas found by trenching.
His wife was actively involved in the Button Mine, but after her death in 1994 he delegated the operation
to a daughter, Charity, to whom he intends to leave the mine. Mr Manjengwa now concentrates on his
other business interests.
The mine is also typical of its type in Zimbabwe in that it cannot be considered very successful. Although,
on paper at least, profitability should be adequate, the operation is poorly funded. Activities are
conducted on a day-to-day basis and the employees are living in poverty.
This is significant because the environment for small-scale mines in this country is probably the most
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favourable in Africa. The mining law gives full transferable rights to claimholders, technology is available
locally from a number of sources, including the Shamva Mining Centre nearby, and gold is purchased at
the prevailing international price and exchange rate by the Government. This study explores the reasons
behind this failure to exploit these opportunities, and suggests how they might be overcome.
The physical and geological environment
The predominant feature in the district is the Mazowe river, which is up to 100 metres wide during the
rainy season. During the dry season a system of weirs ensures that much of the length of the river remains
full. The river winds in a generally north-easterly direction towards the Mozambique border (9). The river
valley is about 2 km wide in the area of the mine and is enclosed by two ranges of hills which rise steeply
to about 300 metres above the flood plain. The Button mine is about 1 km from the river, on the north
side of the southern range.
Vegetation in the area varies with the type of soil and rock and with the altitude. The hills on which the
mine is located are composed of greenstone (a geological term for any altered igneous rock) on which the
principal vegetation is the mfuti tree (brachystegia boehmii) and other brachystegia species. Rainfall is
largely between November and April and is typically 700-900 mm a year.
The country around the Button Mine consists of Archaean granite-greenstone terrain. The gold geology is
hydrothermal -- i.e. the gold and other minerals originated from silica-rich solutions that were forced into
fractures and weak (sheared) zones in the greenstone rocks from the intruding granite masses. As a result,
the gold is found in quartz reefs and siliceous shear zones.
Mining activity in the area predated the arrival of the Europeans by hundreds of years. It appears to have
begun in about AD 800 and continued to the 18th century. Portuguese traders and explorers were active
in the region in the 16th and 17th centuries before being driven out. The next Europeans arrived in the
1890s, attracted by the reports of gold, and a number of mines started, nearly all being sited on ancient
workings.
The main gold mine in the area is the Shamva operation of Lonrho Mining (Zimbabwe) Ltd., with an
annual output of about 600 kg of gold. It is situated on the main (tarred) road to Harare, about 17 km
from Button Mine. Administratively, the Button Mine falls under Murewa district but the village of Shamva
is the source of supplies, postal and health services.
The mining operation
The three current claim blocks are identified for convenience as "New Button Mine". The earlier workings
("Old Button Mine") extend NE for about 500 metres. There are many excavations, consisting principally
of a number of short adits into the hillside, following rich "ore shoots" down, typically at an angle of about
45. In addition, there are several open pits that were probably developed in zones of steep-dipping
stringers and flat quartz veins.
Many of these structures are gold-bearing, including quartz reefs 10-20 cm wide, quartz stringers of
varying degrees of fineness and alteration zones where the greenstone has been permeated with silica.
These mineralized features tend to run in parallel in an east-north-east strike (i.e. roughly in line with the
hillside), dipping at about 50 although, as indicated, flat quartz veins can be seen cutting across this trend.
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Historical
The records show that the claims were worked between 1934 and 1937, producing 49 kg of gold from
4,851 tonnes of ore, a recovery of 10.1 gm/t. The claims were repegged in 1975 but the narrow nature of
the payshoots meant that the waste:ore ratio was high. In addition, the gold in the unoxidized zones (which
begin about 15 metres down) was said to be refractory, giving recoveries of only about 30%. The mine
closed in 1976.
The present mine
The claims were repegged in 1986 by Mr Manjengwa. Trenching revealed several areas of mineralization,
some of which were followed up. Currently an ore shoot is being mined down in a 10 metre long incline
that follows the dip of the mineralized zones. The ore is drilled and blasted, hand sorted and the selected
material trucked to the Shamva Mining Centre (SMC) about 11.5 km away (10). No stoping is undertaken
as the operation is too shallow for bulk mining, although the miner is experienced, with a blasting licence,
and is probably competent to supervise a stoping operation (11).
Output
The amount of gold produced has varied. In 1996 it was 1.25 kg, in 1997, 600 grams and in January March 1998 it was approaching 1 kg. Ms Manjengwa does not know how much was produced before
she took over, but from the Shamva Mining Centre records it appears to be typically about 1 kg a year
from about 160 tonnes of ore -- equivalent to a grade of about 7 gm/t. The sorting ratio at the mine is
about 1:0.5 ore:waste, so the amount actually mined is of the order of 240 tonnes annually. Each tonne of
"waste" will usually contain about 1 gm of gold, so the average grade of unsorted ore will be around 5
gm/t, which coincides with an estimate made by the Government's regional geologist in 1987 (12).
Labour
The labour force is composed only of adult males. It has consisted of up to six unskilled labourers and
one miner, but recently only two labourers and the miner have been working the mine, each receiving a
wage (see below). The miner is in his forties, has a blasting licence and has worked in larger gold mines.
He left school after four years of primary education. The labourers are young men who each have two or
three years of secondary education.
The contribution of small gold mines to national output
The modest output of the Button Mine is fairly typical of small gold mines in Zimbabwe. Table 1 shows
data for gold mines in the Shamva area.
Table 1. Gold mines and production in the Shamva area
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Gold output
Number of
kg/yr
Mines
Per cent of all mines
Gold output
Per cent of total
kg/yr
>1 500
2
300-1 500
9
150-300
4
50-150
8
25-50
15
5-25
28
<5
76
Source: Geological Survey Bulletin.
1.4
6.4
2.8
5.6
10.6
19.7
53.5
gold output
47 525
6 840
774
726
531
361
116
83.6
12.0
1.4
1.3
0.9
0.6
0.2
The same pattern applies at the national level. Table 2 shows the number and distribution of gold mines
for a typical year.
Table 2. Gold mines and production, Zimbabwe, 1984
Output
Number of producers
Per cent of total gold output
kg/yr
>300
150-300
60-150
30-60
15-30
<15
Source: Report of Secretary for Mines, 1984.
13
10
15
13
11
475
63
16
10
4
2
5
This data was amplified by Campbell and Pitfield (13). Figure 2 is derived from this paper and shows there
is a natural distribution of mine numbers against output. The Button Mine would fall outside the lower
production limit of the graph, but it is estimated that there have been over 4,000 gold mines in total in
Zimbabwe, and the extrapolated line to the 10 kg cumulative figure would seem to bear this order of
magnitude out. If this is the case, then mines like the Button Mine are probably producing 2-4 tonnes of
gold a year, or 8-16% of the national total of 25 tonnes.
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The future of the mine
There are many pits and short adits on the property and the Bulletin has reported that the narrowness of
the payshoots made bulk mining (i.e. stoping) unattractive. Once below the oxidized zone, however, the
ore is reported to be well-mineralized , with pyrite, galena and sphalerite. Evidently the sulphide minerals
present make the ore refractory. One "Old Button Mine" section that was mined at some depth -- the
"Jackson Reef" -- reportedly gave a recovery of only 30%.
This combination of narrow, complex mineralization and refractory sulphides is a daunting one for any
major investor proposing to bulk mine below the oxidized zone and probably accounts for the lack of
interest by larger mining companies. According to Ms Manjengwa, interest has been shown by Msasa
Mines (the local subsidiary of Australia's Delta Gold Ltd), the Canadian junior Trillion Resources and by
Lonrho Mining (Zimbabwe) Ltd. An assessment by Lonrho of these claims after tributing them and drilling
three diamond drill holes led to the decision to allow an option to purchase the lease to lapse. This
assessment may be taken as typical. This being the case, the Button mine is likely to continue to be
operated as a small-scale mine, wining gold only from the shallow oxidized zone. This zone is necessarily
limited, but the slow rate of mining and the proliferation of pay shoots should keep the mine in operation
for the next 20 years or so. Experience suggests that when the mine closes (and much depends on the
price of gold) the workers will seek employment on other mines in the area. Failing this they will seek
work on mines further afield, usually by moving to towns in other mining areas where they can get news of
local mine developments. The least popular choice, but one which many will have to take, is to return to
subsistence agriculture.
There remains the alternative of developing the mine at depth underground along the lines of the Mont
d'Or "smallworking" nearby. The reasons why this has not happened and how such development might be
encouraged are addressed below.
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Organization and legal status
The Button Mine is a formally registered mine (its three claims have the numbers 14,918, 14,919 and
14,935). These figures show the large number of claims extant in Zimbabwe. Mr Manjengwa, bought
them for the equivalent of a few hundred US dollars in 1986 from the previous owner.
Most mining codes in Africa either forbid or make conditional the transfer of the mining title of small
mines. Zimbabwe, however, inherited a very liberal mining law from colonial times, almost certainly
created primarily because of the unspoken hope that the "mother lode" of the ancient alluvial
conglomerates of the Witwatersrand still remained there.
As a result a "free access", "finders keepers", "use it or lose it" law, based on claims, was adopted for the
country, with very simple systems for the acquisition, maintenance and transfer of mining title -- one that
did not distinguish between sizes and types of mines. Such a system ensures that a good discovery by a
prospector is relatively quickly sold, usually passing through several hands, until it becomes the property
of an organization with the resources to develop it. Appendix 1 summarizes the simple procedures
involved.
The success of this system can be compared with that in Tanzania, a country with an identical gold
geology and very similar potential to Zimbabwe, but with a two-tier system that separates small-scale
mines from larger ones. At the time of writing Tanzania has no medium or large formal gold mines
(although three are being developed), and the 4-5 tonnes of gold produced annually all comes from
unsophisticated, often illegal diggings. Small-scale miners are the usual discoverers of hydrothermal gold in
Africa and all three of the mines being developed (Bulyanhulu, Golden Pride and Golden Ridge) originally
had small-scale miners on them.
Co-operatives have been generally found to be unsuccessful in Zimbabwe when dealing with gold and
precious stones, as the mutual suspicion engendered by fears of other members hiding nuggets or gems
usually causes them to break up after a short time (14). There are, by contrast, successful and
long-standing co-operatives mining chromite and cassiterite in Zimbabwe.
Geological constraints
The hard rock environment of primary gold presents a problem to the small-scale miner, who is generally
has no access to drills and explosives. In addition, hydrothermal gold deposits are usually steep-dipping.
These factors impose the following constraints on the operators of mines like the Button Mine:
--they have to mine underground;
--the effort required to mine and crush the rock means that they can afford to mine only the richest
sections of the reef, using a series of pits;
--similarly, they can afford to extract the gold only from the richest rocks brought to surface;
--most importantly, they are limited to the depth they can work not only because of bad air and
water inflow, but because their mining method (narrow pits) is uneconomic and self-limiting.
Collaboration with larger mines
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Prior to the establishment of the Shamva Mining Centre (SMC) in 1989 the Button Mine used the
services of the Mont d'Or mine about 7 km away for custom milling. The Mont d'Or mine is considered a
"smallworking" in the Zimbabwean context, having been worked down to below 150 metres depth and
with a milling capacity of about 12 tonnes a day. The owner of this operation, Mr Ivan Willis, also
provided some technical assistance to the small-scale miners in the area and allowed them to use his
magazine for storing their explosives.
The SMC provides extension services as well as custom milling facilities. The most important of these for
Button Mine is the availability of a compressor and jack-hammer to drill the holes for blasting. The
alternative is to use a hammer and long chisel, rotating the latter slightly after each hammer-blow. This
very slow and tiring process requires two or three days work to drill a 50 cm hole. The SMC also
provides training in various aspects of mining. Ms Charity Manjengwa has attended courses given by the
centre which she described as "very useful".
Opportunities for collaboration beyond the level provided by the SMC are limited. The major Shamva
Mine, 19 km away, has been operating since 1910 and is over 1,500 metres deep. It treats about 30,000
tonnes of ore a month at a grade of little over 3 gm/t using cyanidation. Its operations are therefore
several orders of magnitude above those of the Button Mine, at technical and mechanization levels which
have little relevance to the problems facing the latter. The Button Mine, however, uses the fire assay
service at the laboratory of Shamva Mine when necessary, for a charge of Z$45 (US$2) a sample.
The Shamva Mine is also one of the 80 mines in the country that has a "proto team" -- a team of miners
trained in the use of self-contained breathing apparatus and first aid, who are available on call-out to
recover persons from hazardous mining situations. In the past, the Shamva proto team has rescued smallscale miners trapped by falls of ground, often with accompanying injuries. However, they are specifically
prohibited from putting their own lives in danger in order to recover bodies.
Equipment availability
While the Button Mine has only hand tools, it qualifies, as a registered mining location, for access to the
Plant Hire Scheme of the Ministry of Mines. Mining and metallurgical equipment is held at three depots in
Harare, Bulawayo and Gweru. Mining equipment, ranging from wheelbarrows to trucks, compressors,
rock drills, hoists and head frames, may be obtained on a lease-hire-buy arrangement without interest.
Metallurgical equipment, for example stamp mills, ball mills and flotation cells, is also available. Any
specific item of equipment which is required, and agreed to by the Chief Government Mining Engineer
(CGME), may be acquired for a specific mining project.
Payment is spread over three years, charged at 30 days in arrears. Failure to pay within 60 days results in
the loss of both equipment and accumulated credit. Ownership of the equipment is transferred to the
operator on completion of the payments. The Button Mine, however, has never used this service because
of the limited use for it on the mine and the cost of transporting equipment.
Working arrangements
At the time of writing (August 1998) the labourers receive Z$500 a month and the miner Z$700 a month,
together with primitive accommodation and basic food. To put these figures in context, the official
minimum wage in the mining industry currently Z$1,019 a month. The wage scales in the industry are
negotiated annually between the mine owners, the Associated Mineworkers' Union of Zimbabwe and the
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Government. When these rates were agreed (October 1997), the minimum wage in mining was equivalent
to about US$85 a month. However, the rapid devaluation of the Zimbabwe dollar since then has meant
that it is now equivalent to about US$50 a month.
The minimum wage applies to workers on any registered mining location -- i.e. a mining claim block or
equivalent -- regardless of the size of mine. However, there are two legal ways of regularizing the pay
situation for small-scale miners. One is to request a special dispensation from the National Employment
Council (NEC) which administers the implementation of negotiated wage rates. This has become fairly
common amongst the "larger" small mines, but it requires the submission of much financial data. The
second is to negotiate a contract with the workers based on a gwaza, or task basis -- so much per tonne
of rock brought to surface, for instance. There is, however, no evidence that small-scale miners have used
either of these options to regularize their employees' situation.
Employment regulations make specific provision for "smallworker" operations. A smallworker is defined
as the employer at a mine where the total number of non-managerial employees is 40 or less.
Smallworkers are exempt from some of the provisions of the agreement, but are still subjected to the
minimum wage requirement. The Mont d'Or smallworking of Mr Willis is what the negotiators had in mind
when this section was agreed.
When challenged on wage rates, the response of small-scale miners is to say that:
--they cannot afford to pay higher salaries and provide better conditions of employment;
--they use the minimum rates negotiated for "Agricultural and plantation workers", not miners.
The wage rates for agricultural workers are very low, about Z$550 a month plus housing and food
provided, although these are usually of a higher standard than seen among small-scale miners.
The workers at the Button Mine do not have a written contract, but their terms of employment include:
--provision of basic foodstuffs (Ms Manjengwa supplies maize meal, meat, cooking oil, salt and
some vegetables);
--a 44-hour week (8 hours, Monday to Friday and 4 hours on Saturday);
--double time at week-ends and overtime.
In practice, small-scale miners almost never work overtime in a formal sense; they will work over a
week-end in exchange for the equivalent time off during the week. There is usually no paid leave; workers
often take unpaid time off for 1-3 months to assist with planting and reaping at their traditional homes
during the rainy season. No safety clothing is provided, and the only such item in use at Button Mine is a
hard hat, the personal property of the miner.
A number of returns and levies are required by the Government from any registered mine. Monthly labour
and production returns are required by the Ministry of Mines; the Department of Taxes requires returns of
wages paid, even when the labour force is paid below the taxable limit (as the workers at the Button Mine
are); the mine owner is supposed to pay 0.125% of the wages monthly to the NEC to cover the costs of
administering the labour agreement; the Government has a national pension scheme that levies employers
3% of wages; and there are also levies for a state training fund (1% of the wage bill), for national
development (5% of the PAYE deduction), 2.7 % of wages for the Workmen's Insurance Compensation
Fund, and 0.15% of turnover for a standards association. In practice, however, mines such as the Button
Mine fall outside the formal mining sector. Partly because of lack of resources in the ministries concerned
and partly for political reasons, the many small-scale mine owners in Zimbabwe are not normally forced
into complying with the regulations and taxes that affect larger mines.
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Equipment used
With the provision of drilling and blasting services by the SMC, only hand tools -- picks and shovels -are used at the mine. The area, on the side of a hill, is dry and so there is no requirement for a pump. All
operations are by hand, including bringing the broken ore to surface, sorting it and loading the 7-tonne
tipper truck to take it to the mining centre.
Gold sale arrangements
The Gold Trade Act of 1964 prohibits the private holding of "unwrought" (i.e. as-mined) gold. Gold
produced by a mine during any one month must be sold to a registered dealer or to the Reserve Bank
within 14 days of the end of the month. Until 1989 the purchasing of gold was largely undertaken by a
commercial bank, Barclays. It has over 40 branches, each being licensed in terms of the Act as a gold
dealer and so able to buy gold produced from any registered mining location.
Payment for gold produced by small mines, including mines such as the Button Mine, is normally made in
two instalments. Payment of 50% of the estimated value of the gold is made within 48 hours. The balance
of the amount due is paid within a week, after the completion of refining of the "lodgement" by the
Reserve Bank's gold refinery, Fidelity Refiners. Bullion payments, which involve a fair amount of clerical
work because of the number of producers (over 350 at any one time) are handled by the Chamber of
Mines on behalf of the Reserve Bank.
Prior to 1988, gold was refined on a toll basis at the Rand Refinery in South Africa. Following the
commissioning of the Fidelity refinery it became mandatory for locally produced gold to be refined there.
The creation of the refinery was initiated by the Ministry of Mines, but the Reserve Bank argued
successfully that as the sole legal holder of mined gold in Zimbabwe, it should operate the plant as a
subsidiary.
The original Gold Trade Act was promulgated in 1940 and it is probably true to say that there has been a
black market in gold in Zimbabwe ever since that time. The premium appears to have varied from 4% to
over 25%, depending on economic and political circumstances. Indeed, from conversations with
small-scale miners during the feasibility work on the SMC in 1987, it seems likely that the reason for the
slow acceptance of the Centre as against other local custom mills in the area -- there were at least three
-- was the perception that its association with government would prevent the sale of the miner's gold on
the black market. This is not an idle fear; the penalties for illegally trading in gold are severe and there is a
special police detachment -- the Gold Squad -- tasked with enforcing the Gold Trade Act.
The official gold buying system worked well enough until about 1989 when new alluvial gold discoveries,
accompanied by increasing poverty following droughts, lead to an explosion in illegal, artisanal gold
production. Much of this was from new and widespread discoveries of alluvial gold resources, when local
miners found that the major river systems possessed rubble horizons on their bedrock associated with
considerable mineral enrichment. At the same time, Barclays Bank withdrew from the purchasing of gold
and closed its laboratories, bringing a "perceived need" (15) for small-scale miners to travel to Harare or
Bulawayo (where there is a branch of the Reserve Bank) to deposit their gold. A further obstacle was
introduced in 1994 when Fidelity Refiners, facing a rush of small deposits, refused to treat lodgements
containing less than 50 grams of pure gold. (Further details of gold buying arrangements are in Appendix
3).
Black market buyers are active in all the gold areas of Zimbabwe and, indeed, the casual visitor to small
scale mines is in some danger of being mistaken for one. Although it was not possible to determine the
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extent to which the Button Mine's output was being sold through this channel, it may be taken that at least
some of it was.
Compared with gold selling arrangements in other parts of Africa, the small-scale miners in Zimbabwe
receive a high proportion of the value their production.
In Tanzania a levy (royalty) of 3% of the value of the gold is charged by the Central Bank. This is in fact
an export tax, but it is normally charged when the deposit is lodged with the Bank. In Burkina Faso the
Comptoir Burkinabé de Métaux Précieux deducts approximately 10% for its purchasing and marketing
services. Neither country credits the producer with the silver content of the bullion as in Zimbabwe.
In Zimbabwe the refinery makes a deduction of 0.15% of the weighed and assayed value of the bullion
lodged, and levies a refining charge on the balance which is currently equivalent to another 0.15% of the
value. These are conventional order-of charges for bullion delivered to gold refineries, similar rates being
charged by the Rand Refinery. Against this, however, must be weighed the unwillingness of Fidelity
Refiners to handle small lodgements.
In 1995 the gold buying system was liberalized and gold trading licences were issued to a number of
Zimbabwean businessmen who have partly supplanted the black market dealers. They usually charge a
fee of about 1% of the assessed value of the gold for purchasing and transporting the small-scale miner's
bullion.
The revenue from the output of a mine like the Button Mine (about 1 kg a year), will have fallen from
about US$13,000 to about US$10,000 over the past three years following the declining gold price. But
since the Zimbabwe dollar has devalued by about 50% in the same period, revenue per kilogram of gold
in local currency has increased from about Z$130,000 to about Z$160,000.
Ore treatment: The Shamva Mining Centre
The technology used at the SMC and other custom mills is simple and well-established, as might be
expected. In general, the crushing of the ore at such operations is by stamp mills, in part because of their
simplicity and robustness and their ability to treat small batches, but also because they do not need a
separate crushing unit to reduce the ore to a treatable size. However, a major reason for the preference is
their longevity. Although stamp milling went out of favour with larger mines over 50 years ago, the
superseded mills were bought by smallworkers and small-scale miners and most of them are still in use.
The SMC began using a small stamp mill, but found after three or four years that it was inadequate for the
demand. A locally made jaw crusher and ball mill are now used, with a capacity of about 20 tonnes a
day. The miner provides the labour for operating the plant during the time that his ore is being fed through
it, under the supervision of the SMC manager.
The crushed ore is milled in water to give a "pulp" of about 30% by weight of solids. The "free" gold (i.e.
that which is not trapped inside particles of ore, or is in association with sulphur-containing minerals) is
normally recovered on a shaking table or a locally made centrifugal concentrator. These produce a
concentrate of free gold together with the heavy minerals in the ore, such as magnetite and iron sulphides.
This gold is extracted by milling it with steel balls and mercury in an "amalgam barrel". This process also
liberates some of the gold trapped in sulphides.
The amalgam barrel is discharged over an amalgam plate -- a copper plate which has been rubbed with
mercury. Gold and gold-amalgam from the amalgam barrel passing in contact with it adhere to this
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surface. Gold is recovered by scraping off the amalgam from the plate and retorting it to volatilize the
mercury. The latter is recovered in a water-cooled condenser, and the gold is left behind in the retort as a
porous lump.
The miner pays for the use of the plant and takes away his amalgam gold. Currently the plant hire rate is
Z$95 an hour, or about Z$60 a tonne (about US$4). No other arrangement is acceptable to the
small-scale miner. Without exception, attempts to introduce systems that pay for the contained gold in ore
before treatment have foundered over arguments as to how much gold was present. Indeed, the SMC
used to charge by the tonne (10 wheelbarrows) until disputes over this measurement made it necessary to
work on a hourly basis.
The tailings from the shaking table or centrifugal concentrator are piped to channels, where the coarser
particles (`sands') settle out and are shovelled out to dry. The fine 'slime' portions are allowed to settle in
a slimes dam. After drying the sands have their residual gold content partially recovered by the
percolation of a cyanide solution through them. Slimes do not allow the passage of solution and the gold
remaining in this fraction (which is normally fairly low grade, about 1-2 gm/t) requires agitation in a mixing
tank, using a stirring device or compressed air. However, once dry, it is possible to mix some of the
slimes back with the sands for cyanidation by percolation. Gold is recovered from the cyanide leach by
passing the filtered and clarified solution over zinc shavings or over carbon particles. This gold is the
property of the SMC and accounts for most of its revenue. Between 1989 and 1994 the average
amalgam gold recovery for the small-scale miners was equivalent to about 5 gm/t and the SMC's cyanide
gold recovery was about 1 gm/t.
Relations with authority
The formal structure of the Zimbabwe mining industry is built around the revised Mines and Minerals Act
(Chapter 21.05) of 1996. The function of the Ministry of Mines is to administer the Act and its attendant
regulations:
--Mining (General) Regulations, 1977, Rhodesia Government Notice No. 247 of 1977;
--Mining (Management and Safety) Regulations, 1990, Statutory Instrument 109 of 1990;
--Mining (Health and Sanitation) Regulations, as amended Statutory Instrument 182 of 1995;
--Explosives Regulations, 1989, Statutory Instrument 72 of 1986.
As far as the average small to medium-size mine is concerned, technical support is encountered most
frequently through the services of the regional representatives of the Ministry, who are sited in five centres
(Harare, Bulawayo, Gweru, Masvingo and Kadoma). These services are nominally very comprehensive,
but have suffered from the erosion of the budgetary allocations to the Ministry, which are currently only
about a third in hard currency terms of the level in 1981.
The key regulatory authority is the Chief Government Mining Engineer's (CGME's) office and its regional
offshoots, which have the responsibility for administering the regulations. In addition, the CGME's
department provides free survey, ventilation and sampling facilities and also administers the Mine
Manager's Diploma examinations and the Mine Surveyor's Certificate of Competency examination. There
are positions for eight graduate mining engineers, seven mining technicians and 20 survey technicians in the
department, the last two categories being largely diplomates of the Bulawayo School of Mines. The total
number of positions in the department is 128.
In theory, the responsible owner or manager of a mine must sign a form acknowledging responsibility for
the observance of the regulations, and in the past inspections were normally carried out by the regional
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Government Mining Engineer every three months. In practice, however, small-scale miners operate in
contravention (or at least in ignorance) of these requirements. Moreover, the lack of transport has meant
that inspections of even major mines have become increasingly infrequent.
The Button Mine has been inspected only once in the past four years, when members of the CGME's
department visited it while on their way to the scene of an accident at another mine. Because of the limited
underground development at the mine and the competent nature of the rock, no recommendations were
made during this visit. The mine has also been visited on at least one occasion by staff from the Geological
Survey and some advice given. This department has a total establishment is 62, with geological mapping
undertaken by a team of nine field geologists. There are regional offices in Harare, Gweru and Bulawayo.
Eight geologists are involved in these offices, together with two economic geologists.
The Button Mine has also benefited from geological advice provided through the SMC, most recently
when a geologist took a party of women miners around the operation. In the past, the Button Mine has
used the services of the Government Metallurgical Laboratory (GML) which provides an important free
metallurgical and assay facility to the industry. Its main function is to test the recovery of all potentially
valuable minerals which exist in Zimbabwe. Understandably, the evaluation of gold prospects and
pegmatite minerals has been particularly important.
There are a number of other Government agencies that are supposed to visit the site, including the
Ministry of Health, which jointly administers the Mining (Health and Sanitation) Regulations, and the local
Rural Council, which levies rates on property owners and claim holders to cover road upkeep, etc. no
such visits appear to have occurred in the past four or five years.
Technical, financial and administrative constraints
Constraints to the growth of the Button Mine are analysed in detail below. The main problem facing the
mine is financial. Technical know-how is available through the SMC, from the Ministry of Mines and
(perhaps most importantly of all) from the successful activities of smallworkers in the area. There are no
administrative constraints at present, although any significant growth in the operation will bring it into the
tax- and levy-paying domain of larger mines.
The evidence from, for example, the Lonrho investigation, is that the reef structures are modest, but
consistent at depth, providing the argument for installing a proper shaft and developing stopes. Lonrho
detected a barren mineral intrusion (dyke) below about 85 metres, but this would still leave ample
resources for a small mine the size of the Button Mine to develop above it. The technology involved in this
development is described in Appendix 2.
Such progress is costly. To sink a shaft and equip it at the Button Mine, together with the development
required to block out two stopes, would cost about US$60,000, equivalent to all the gold the mine has
produced in total during the past four years.
This money will be very difficult to raise. Banks will lend money on the strength of proven (i.e.
blocked-out) ore reserves, but not on the basis of a couple of drill core intersections and a rather negative
report from a company like Lonrho. Some assistance can be gained from the plant hire section of the
Ministry of Mines, but this unit is currently servicing about 80 account holders and there is very little
relevant equipment currently available.
In the past four years a donor-funded organisation in Harare, the Foundation for Small Mines, has used
Austrian aid money to try to bridge this gap. Ms. Manjengwa has been given their address details and
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encouraged to contact them.
Safety and health
There have been no accidents notified at the Button Mine since Mr Manjengwa began mining there six
years ago, and the SMC noted in 1995 that it has recorded no fatal accidents amongst its users since it
started in 1988. However, it is quite possible that there have been injuries from unrecorded accidents.
The principal causes of deaths in all mining in Zimbabwe in 1997 are shown in table 3.
Table 3. Mine fatalities in Zimbabwe, 1997
Cause of Accident
Falls of ground
Machinery; vehicles
Shaft accidents
Gassing
Electrocution
Explosives
Miscellaneous
Total
Source: CGME's office.
No. of deaths
%
13
13
11
5
2
4
5
53
25
25
20
9
4
8
9
100
This pattern has been consistent for many years. Thus for the period 1982-91 falls of ground,
machinery/vehicles and shaft accidents were the top three causes of fatalities in Zimbabwe' mines.
The Button Mine is a shallow underground operation in competent rock, there is no machinery in use
except when the SMC's compressor is employed, it has no shaft, uses explosives intermittently and in
fairly well ventilated conditions and has no electricity. Its workers are therefore less exposed to most of
the hazards that exist in larger mines. Nonetheless, small-scale mining has a well established reputation for
a disproportionately high number of fatalities. This has arisen principally from the deaths caused by such
miners re-entering closed mines illegally to win gold from the pillars, and from alluvial miners burrowing
into uncompacted river banks. However, many such deaths are believed to go unreported. One estimate
from the CGME's office is that there could be about two fatalities a month among such miners, of which
only about a quarter appear in the official statistics.
Injuries to miners tend to arise from the same causes as fatalities, except that lashing operations -- moving
broken rock -- are a major source of minor lost-time accidents, replacing shaft accidents as the third
most common cause of accidents.
In the event of an accident the nearest source of first aid is at the SMC, 12 km away. From there the first
aid facilities at Shamva Mine can be used (17 km). However, the nearest hospital with facilities for dealing
with serious injuries is at Bindura, about 60 km away.
Apart from occupational hazards, the health of the miners in the area is not satisfactory. The miners at the
Button Mine report that they suffer from malaria in the wet season. Water-borne diseases are endemic;
the water supply for the mine is drawn from a (usually) perennial stream about 300 metres away, without
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filtration. Bilharzia (schistomosiasis) as well as enteric infections are common. Cholera has become
established in the eastern part of Zimbabwe, following the arrival of migrants from Mozambique and is a
potential threat to those, like the miners at the Button Mine, who depend on a local open water supply.
Normal health problems are usually treated at the Government clinic at Shamva town, about 18 km away.
The most important occupational health threat to the miners arises from the silica dust they inhale. In larger
mines, underground workers and those in dusty surface areas, such as crusher sections, undergo an
annual respiratory check-up, including a chest x-ray. Workers who show deterioration in their respiratory
capacity, or a lung shadow, must be withdrawn from work in such areas (16).
This is not a minor precaution. The incidence of incipient silicosis among gold miners in Zimbabwe is so
great that some mine managers of smaller mines have complained that they are running our of work in
non-dusty areas for those at risk. The control of silicosis and other respiratory diseases caused by dust is
administered through the Pneumoconiosis Act (Chapter 15:08, revised 1996) and pensions for those
partially incapacitated by such diseases are paid from the Workmen's Compensation Insurance Fund.
Typically, in any year, 30-50 mineworkers are pensioned or compensated by the Fund on behalf of the
Pneumoconiosis Bureau. It appears, however, that none of these come from the small-scale mining
sector.
Environment
In common with most small-scale mines, the environmental problems arising from the activities at the
Button Mine are mainly connected to health hazards arising from the unplanned nature of mining
communities. Other problems arise from the unprotected nature of the workings -- pits and trenches are
not fenced or walled, let alone filled in, and livestock occasionally falls in to such excavations. The Button
Mine staff said there had never been any human accidents arising from these hazards.
The SMC provides a retort for recovering mercury and amalgam gold so none is lost to the environment.
The retort is one of the standard type commercially available in Zimbabwe for the equivalent of about
US$20.
The cyanide used at the SMC for treating tailings is in closed circuit, and checks on the streams in the
area show no evidence of cyanide loss. The antidotes prescribed in terms of the mining regulations are on
hand in the SMC plant.
Discussion
As noted above the Button Mine is typical of its type in Zimbabwe in that it cannot be considered very
successful. The mine has remained a near-surface digging, despite the potential for deeper mining, and
there have been no attempts at exploiting this opportunity.
The annual output from the Button Mine is about 1 kg of gold from about 240 tonnes of ore mined and
160 tonnes transported and milled. In 1997 this amount of gold would have realized about Z$150,000 at
the then exchange rates and gold prices. Table 4 sets out the direct costs involved.
Indirect costs that are not considered here include those of travel to and from the mine (which is done by
bus at about Z$6 a passenger) and the owner's costs. Nonetheless, the annual net revenue from the mine
should, in theory, be at least Z$50,000 annually, or about US$4,000 at 1997 exchange rates.
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Table 4. Button Mine direct production costs
Cost item and unit
Labour
2 workers for 12 months
1 miner for 12 months
Food for 3 employees for 12 months
Compressor hire (10 days/year)
Transport 160 t to SMC (7 tonne truck)
Milling charges at SMC (tonne equivalents)
Miscellaneous (inspection certs., hand tools, etc.)
Total
Cost/unit (Z$)
500
700
200
650
700
60
1 000
Units
24
12
36
10
23
160
1
Total (Z$)
12 000
8 400
7 200
6 500
16 100
9 600
1 000
60 800
The trap in which the Button Mine finds itself in is a common one -- that the cost of developing to the next
stage, with some mechanization, leading to a supply of cheap ore from stoping (see Appendix 2) will cost
much more than these modest returns can provide. The Button Mine is probably capable of supporting a
10 tpd operation for a number of years. The Lonrho inspection suggested a potential of three payable 1
metre wide reefs above the dyke at about 80 metres depth, equal to about 15,000 tonnes of ore.
However, as noted above, even this limited development will require a capital expenditure of about
US$60,000, or perhaps 15 years of normal profits.
These constraints account for a feature of small-scale mine owners noted elsewhere by the author -- in
Tanzania, for example. Faced with a limited income from a resource whose more profitable development
is out of the question, mine owners invest their revenue from mining outside the sector, in less capitalintensive areas or in more robust assets. Mr Manjengwa, for instance, has expanded his trading
businesses and has built a house with 16 bedrooms in Bindura since he acquired the Button Mine.
There is a need therefore for more financial encouragement to small-scale miners who possess resources
with development potential. The SMC is unique of its kind, but of its 220 or so users, only two have
indicated that they are actively trying to expand their mines to a more economic size, despite the fact that
Zimbabwe is one of the few countries in Africa where such transformations are not hindered by legal and
technical constraints.
The Button Mine is not unique it its potential to grow into a larger operation (albeit still a small mine by
any standards); probably 10-20% of the users of the SMC will fall into this category. There is thus no
shortage of opportunities; rather it is the shortage of risk capital and entrepreneurial skills that inhibit
development of small mines in Zimbabwe.
There is a need to draw the attention of the new business and professional elite that has arisen in the
country to the opportunities for growth that small-scale mines like the Button Mine present. Mr
Manjengwa, the claim holder, is clearly one of these. If this is done, then there will be numerous new
employment opportunities in small mines, but in a healthier, safer and more prosperous environment than
at present.
Conclusions
The Button Mine is typical of small-scale mines in Zimbabwe, producing about 1 kg a year of gold from
shallow underground workings. It employs a handful of workers who live and work under primitive, often
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unhealthy, conditions and, despite being legally registered, the mine operates largely outside the formal
sector.
The mine uses the services of the Shamva Mining Centre to drill and blast and to recover the gold from
the ore, relegating the mineworker's activities to hoisting, sorting, loading and operating the SMC mill. No
significant resources have been put into the mine and it therefore has remained undeveloped, despite the
evidence that there are significant amounts of ore at modest depths.
The Button Mine is representative of a large number of such mines in Zimbabwe -- certainly several
hundred -- whose workers would benefit from the development of the operations towards their full
potential. There is a case for encouraging the NGOs active in this area, such as the Shamva Centre and
the Foundation for Small Mines, to assist local entrepreneurs and businessmen in assessing and exploiting
these opportunities, leading to increased employment in a healthier, safer and more prosperous
environment.
For further information, please contact the Sectoral Activities Department (SECTOR) at Tel: +41.22.799.7513, Fax:
+41.22.799.7296 or email: [email protected]
Disclaimer | Copyright © 1998 International Labour Organization (ILO) | [email protected]
This page was created by CG. It was approved by NJ. It was last updated on Monday, 20 October 1999
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