OVERVIEW OF THE IMPACT OF MINING ON THE ... - IIED pubs

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2.4.4 Siltation Siltation is the process whereby fine solid particles build up on the bed of a river or lake and is the result of an excessive load of suspended solids in a river or rivers. Mining operations produce large quantities of dust and finely powdered rock, with much rock having been ground to particle sizes below 0.2 mm. Though the materials that are dumped after removal of the commodity being mined have fine particle size and reasonable physical characteristics that could permit plant growth and retain adequate amounts of water, these materials have been formed from hard unweathered material and so may not contain much of the finest clay material and lack organic or microbial activity. The result is that mine dumps may be very unstable, easily blown by wind when they are dry and eroded by heavy rain when wet. The action of rain and wind thus removes fine particles into nearby water systems, leading to a build up of suspended solids and ultimately siltation. 2.4.5 Water use Mining operations are major users of water, most notably for: 1. Cooling; 2. Underground operations, such as hydraulic drills; and 3. Processing, such as flotation and leaching. Larger mines also frequently use large quantities of water to supply nearby residential areas attached to the mines, such as mine housing units. In arid and semi-arid areas, the quantity of water used by a mining operation places it in direct competition for water with other water users, especially domestic, agriculture and the aquatic environment. This “competition” becomes heightened when the mining operation is also responsible for any deterioration in water quality as a result of effluent discharges. Typically, however, the authority responsible for granting the mining permit will also work in collaboration with the authority responsible for granting permits for water abstraction and effluent treatment and discharge. When this collaboration is effective, it ensures that the quantity of water used by the mining operation is within the allowable limits posed by the available water within the catchment concerned. If insufficient water is available in the catchment, and the social and economic opportunities offered by the mining operation are sufficiently attractive, additional water may be brought in from a neighbouring catchment. lviii
This process is carefully balanced to ensure that the prevailing principles of integrated water resource management (or integrated catchment management) are upheld. In certain mining operations, (e.g. the Witwatersrand gold mines), the mines may be located in a dolomitic area that is characterized by large volumes of ground water. This ground water normally has to be removed and discharged into surface streams and rivers so that the underground mining operation may proceed. In such cases, this apparent “additional” water may provide a useful source of water for other surface water users in the catchment. 2.5 Small-scale mining 2.5.1 Alluvial gold mining Alluvial gold mining has been carried out in many rivers across Mozambique, Tanzania, Zambia and Zimbabwe, mainly by small-scale operators using picks, shovels and panning dishes and sometimes sluice boxes. In Zimbabwe, mechanized mining was also applied in areas such as the Angwa River and the Ruenya River, both located in the Zambezi basin (Chiyanike, 1997). The numbers of small-scale gold miners fluctuate widely from year to year, often in response to the presence or absence of alternative employment. Given the large numbers of small-scale miners, there is substantial physical impact due to the extensive diggings and workings, for example: the upper reaches of the Ruhuhu River in Tanzania and the Mazowe River in Zimbabwe. The normal gold recovery process in Zimbabwe is the stamp mill and amalgam plate (Holloway, 1993) and subsequent recovery of the gold from the amalgam using mercury (Love, in preparation). Mercury is frequently lost in this process, causing significant contamination of the water systems. 2.5.2 Small-scale chrome mining Small-scale mining of chrome takes place along the length of the Great Dyke in Zimbabwe, especially in the Mutorashanga and Lalapansi areas, as well as southeast of the Mweza Range. The most important impact that these workings have is the stripping off of large quantities of soil, leading to enhanced erosion and increased sedimentation of nearby watercourses. 2.5.3 Gemstones and semi-precious stones lix
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AN OVERVIEW OF THE IMPACT OF MINING
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AN OVERVIEW OF THE IMPACT OF MINING
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exploited, the size of the facility
Page 7 and 8: 2.3.6 Stockpiling and transport of
Page 9 and 10: 4.1.6 Mining and mineral processing
Page 11 and 12: LIST OF FIGURES Figure 1.1: Compari
Page 13 and 14: Table 1.6: Minimum annual productio
Page 15 and 16: Table 3.26: Mining operations in th
Page 17 and 18: Table 4.22: Mining operations in th
Page 19 and 20: ACKNOWLEDGEMENTS Several enthusiast
Page 21 and 22: 1. INTRODUCTION AND BACKGROUND INFO
Page 23 and 24: Box 1.2). Each research team is req
Page 25 and 26: The MRC cannot be held responsible
Page 27 and 28: of amenity or deterioration in wate
Page 29 and 30: Typically, river flows in the count
Page 31 and 32: In simple terms, all of the propone
Page 33 and 34: shared by more than one country, es
Page 35 and 36: most appropriate technical or inves
Page 37 and 38: CAMEROUN GABON CENTRAL AFRICAN REPU
Page 39 and 40: 1.6.1 Data on the location, nature,
Page 41 and 42: 1997). In future studies, more atte
Page 43 and 44: Section 5 briefly reviews the water
Page 45 and 46: Mining methods vary widely and depe
Page 47 and 48: Removal and storage of ores and was
Page 49 and 50: These effects are usually ameliorat
Page 51 and 52: Water quality changes are widely co
Page 53 and 54: these substances are often mobilize
Page 55 and 56: The acidification of the water has
Page 57: and kinetic stability of the comple
Page 61 and 62: neutralize each other - this situat
Page 63 and 64: (Chenje, 2000). Despite the recent
Page 65 and 66: Swaziland Water Environment Tanzani
Page 67 and 68: Draft Environmental Management Bill
Page 69 and 70: siting of works plan for approval t
Page 71 and 72: The draft policy encourages develop
Page 73 and 74: provides a definition but one which
Page 75 and 76: 2.9.3.9 Zimbabwe Environmental Impa
Page 77 and 78: Sector Activity Industry °Chemical
Page 79 and 80: Cyanides and related compounds (CN)
Page 81 and 82: of Natural Resources and the South
Page 83 and 84: 3.1.1 Geology, topography and soils
Page 85 and 86: Air temperatures across the Zambezi
Page 87 and 88: or fuelwood production. Similar pat
Page 89 and 90: Zambia. Clearly, some water quality
Page 91 and 92: 3.2.1.6 Human impacts on water reso
Page 93 and 94: The Botswana segment of this area f
Page 95 and 96: 3.4.1.4 Surface water users The onl
Page 97 and 98: 3.5.1.2 Geology The Upper Karoo Bat
Page 99 and 100: 3.5.6 Implications for water qualit
Page 101 and 102: 3.6.4 Monitoring systems None. 3.6.
Page 103 and 104: 3.7.2 Mining and mineral processing
Page 105 and 106: 3.8.1.5 Water management systems Th
Page 107 and 108: 3.9.1.2 Geology This sub-catchment
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3.9.5 Water quality data None avail
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Z-87 Mulobezi Amethyst Operating Ve
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3.11.1.6 Human impacts on water res
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3.12.1.2 Geology This sub-catchment
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• Increased quantities of suspend
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Determinant Fischer’s Farm Raglan
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3.13.1.4 Surface water users There
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The Nampundwe pyrite mine poses a r
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Z-90 Chisuki Mica, Tin, Tantalite O
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along the major roads between Chiru
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3.16.1 General description 3.16.1.1
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Z-17 Jessie Gold Starting Very Smal
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Small intrusions of Greenstone form
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Several stretches of streams and ri
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3.18.1.5 Water management systems T
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3.18.6 Implications for water quali
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3.20 The Mazowe (Mozambique) sub-ca
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3.20.4 Monitoring systems This area
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Table 3.21: Mining operations in th
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The only settlements of any size ar
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3.23.4 Monitoring systems None. 3.2
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• Non-point impact from minefield
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This is Zones G1-G6, B1-B3, S1-S6,
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The catchment falls mainly under th
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The two lone water quality data poi
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• Non-point domestic effluent, ru
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Land use comprises the Siabuwa, Oma
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3.28 The Ume sub-catchment 3.28.1 G
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3.28.4 Monitoring systems None. 3.2
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3.29.1.4 Surface water users The Ci
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Thristle Etna Gold 6.7 Medium Tiger
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Sanyati, all may well contribute or
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3.30.1.5 Water management systems T
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This is Zone Z1 of Area C (ZSG, 198
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3.31.5 Water quality data Only one
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3.32.2 Mining and mineral processin
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Land use above the Zambezi Escarpme
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Extensive alluvial mining of gold t
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The major settlements are the metro
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• Urban run off, urban areas of C
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3.36.1.4 Surface water users The to
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3.37.1.1 Hydrology This is Zones M1
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The catchment falls under the Harar
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3.37.3 Alluvial mining Alluvial min
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widely intruded by Mashonaland Dole
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3.38.4 Monitoring systems ZINWA is
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4. THE LIMPOPO BASIN In order to pr
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Mountains. Most of the basin consis
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the City of Pretoria and the northe
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continues to flow in the deeper all
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Each basin state maintains its own
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Land use in the upper parts of the
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the Limpopo River some 100 kilometr
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None obtainable in time for this re
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4.4.2 Mining and mineral processing
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In the Botswana sector of the sub-c
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Table 4.9: Mining operations in the
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4.7.4 Monitoring systems ZINWA is c
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There is exploration for diamonds (
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There is exploration, mainly for di
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Hwange National Park (ZSG, 1998). A
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4.12.1.3 Pedology, agriculture and
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4.13 The Marico sub-catchment 4.13.
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• Major non-point impact of agric
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Several thermal springs are located
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• Disposal of large volumes of li
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D7-13 Premier Diamond - kimberlite
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Most of the clayey loam soils in th
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4.17 The Theuniskloof sub-catchment
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4.17.4 Monitoring systems The Depar
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4.18.1.4 Surface water users All of
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Water quality data for three sites
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supplies in the sub-catchment, the
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4.20.1.2 Geology Like the Mogalakwe
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• Minor non-point impact from non
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4.21 The Nzhelele sub-catchment 4.2
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4.22.1.3 Pedology, agriculture and
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Code Number Name of Mine Commodity
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5. THE OLIFANTS CATCHMENT In order
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Soil formations across the Olifants
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indices of per capita agricultural
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professional capacity within the me
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• Dark grey to blackish, mottled
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5.2.5 Water quality data No specifi
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Several towns (e.g. Witbank and Mid
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The following mining operations are
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5.3.6 Implications for water qualit
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5.4.1.3 Pedology, agriculture and l
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K 5.5 5 4.5 Cl 380 350 200 F 1.0 1.
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local geological formations. High c
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The South African Department of Wat
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pH 8.5 8.3 8.8 8.7 8.8 8.9 TDS 439
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Soils in the sub-catchment can be d
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No information is available on the
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In its upper reaches, the sub-catch
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The Phalaborwa Water Board has been
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m 3 /day) water abstractions, and m
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In the south-west of the sub-catchm
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• Minor non-point impact of agric
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(Figure 4.2). The tributaries of th
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5.9.1.6 Human impacts on water reso
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y the upper Klaserie River. Recent
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In Mozambique, the Mozambican Depar
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Acid mine drainage (AMD) represents
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• Antimony, cadmium and tin conta
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• Decreased light penetration to
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6.1.8 “Peripheral” or indirect
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Worldwide, the general public has e
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2. That copies of this report shoul
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Banks, D., P.L. Younger, R.T. Arnes
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CSIR (1993). An Environmental Impac
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Fuggle, R.F. & M.A. Rabie (1996). E
Page 355 and 356:
Love, D. & D.K. Hallbauer (2000). M
Page 357 and 358:
Pettersson, U.T. & J. Ingri (2000b)
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Turton, A.R. (1999b). Water scarcit
Page 361 and 362:
World Bank (1998). World Developmen
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