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Francis Cottard
BRGM / Environment & Process Division

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  1. 1. 1st MINEO Workshop 25-27 October 2001, GBA, Vienna, AustriaPOTENTIAL ENVIRONMENTAL IMPACTS OF MINING A SHORT ILLUSTRATED REVIEW BY Francis Cottard BRGM / Environment & Process Division 1
  2. 2. POTENTIAL ENVIRONMENTAL IMPACTS OF MINING CONTENT 1) INTRODUCTION nature of mining sources & mining life cycle MINING METALS 2) SET OF EXAMPLES CONCENTRATING METALS REMOVING IMPURITIES 3) OTHERS ASPECTS ancient mining & abandoned mines socio-economic impacts & public safety positive impacts 4) CONCLUSIONS how science & technology can help ? 2
  3. 3. INTRODUCTION Some facts on the nature of mining sourcesP Mining has been an integral part of the development of civilizationP Early mining operations have left a historical legacy of negative environmental impacts that affect our perception of miningP A mine is a waste management project = A new paradigm to meet the global objectives for sustainable development in the 21st century 95% of the material excavated from a mine are waste materials generally left at the surface Some large operations handle more material and generate more waste than many entire industriesP Major impacts are resulting of negative changes in geochemistry over time, when a material ’s environment changes (e.g.: from a reducing environment to an oxidizing one…) 3
  4. 4. INTRODUCTION (2) Some facts on the nature of mining sourcesPThis long- term nature of mining impacts requires that predictive tools, design performance, monitoring, be effective for many decades.P Potential Environmental Impacts are greatly influenced by geological factors : - deposit size - host rocks lithology & wall rock alteration - nature of ore & trace element geochemistry - ore & gangue mineralogy and zonation - secondary mineralogy - topography, physiography & climate - hydrology - mining & milling methods employed - ... 4
  5. 5. Simplified Mining process and global Impacts on water Rainfalls Waste rocks Leaching Mine water discharge Ore processing Tailing dams Smelting Extraction SeepageModified Water wellspathways 5
  6. 6. Mining Life Cycle PROCESS WASTE MEDIA AND HAZARD MINERAL DEPOSIT NATURAL LEACHING LAND DISUSED Land degradation MINES Land fragmentation Open pit or Soil disruption underground mining Soil contamination WASTE Erosion ROCKS ORE Mining metals WATERLeaching Milling DUSTS Groundwater table alteration Spring and borehole yield EFFLUENTS River or surface water diversion Turbidity Contamination of rivers TAILINGS Acid Rock Drainage (ARD)METALS IN CONCENTRATES LEACHATE PONDS TailingsSOLUTION SLAGS Concentrating metals 6
  7. 7. Mining Life Cycle (2) PROCESS WASTE MEDIA AND HAZARD METALS IN CONCENTRATES SOLUTION SULPHURIC AIR Smelting ACID Carbon oxides (pyrometallurgy) Sulphur oxides Solvent Nitrogen oxides extraction Methane AIR Electro- CFOs BLISTER METAL EMISSIONS winning Dusts (radioactive, toxic or nuisance) Refining SLAGS METALS IN CATHODES WIRE BARS DUSTS ACTIVITIES GENERATE Fabrication Heat Noise SCRAP Vibration METALS PRODUCTS METALS Removing impurities 7Modified from warhurst 1999
  8. 8. Main Surface Components of a Mine Site in Activity Tailings dams Overburden dump Waste dumps Open pitRailway Processing plant 8
  9. 9. Mining metals (1)Physical disturbance to the landscape Sibai copper mine ( Russia ) 9
  10. 10. Mining metals (2) Waste Rock disposalActive dumps Old dumps Uchaly copper mine ( Urals / Russia ) 10
  11. 11. Mining metals (3)Erosion of waste rocks dumps Tentative of revegetation Sibai copper mine (Russia) 11
  12. 12. Mining metals (4) Erosion and sedimentation process lake River bed Tailings redepositionRosia Poieni mine(Rumania) Aveyron river La Baume Pb / Zn ancient mine (France) 12
  13. 13. Mining metals (5) Acidic and metals-bearing soils and water Rosia Montana gold mine (Rumania)Assarel copper mine(Bulgaria) 13
  14. 14. Concentrating Metals (1)Accumulation of Tailings containing residual chemicals deposition of gray unoxidized sulfidic tailings Pyrite-rich tailings impoundment in Russia 14
  15. 15. Concentrating Metals (2) Erosion of Tailing Dumps by Wind and Water Sulfidic tailings 8 % AsMechanical erosiondispersiondissolutionsedimentation... ENGUIALES Tungsten mine ( France ) 15
  16. 16. Concentrating Metals (3) Production of Acid Mine Drainage Rosia Poieni ( Rumania )Plant tailings Acidic water pH= 2.5 tailings Acidic water Karabash area ( Russia ) 16
  17. 17. Concentrating Metals (4) Effects of Acid Drainage Overburden dumps Rosia Poieni ( Rumania ) River bed destruction Surface water quality degradationCalimani Mine (Rumania) 17
  18. 18. Concentrating Metals (5)Gold Cyanide Heap Leaching Gold heap leaching Pilot test 18
  19. 19. Mining and Concentrating Metals (6) Cumulative Impacts Hillsides devegetation Soils erosion Slag disposal Tailings deposition Acidic water generation Karabash mining area (Russia) 19
  20. 20. Removing impurities (1)Smelter stack emissions and release to air SO² Pb ? Hg? Cd Karabash copper smelter (Russia) 20
  21. 21. Removing impurities (2) Metals and dissolved pollutants from slags disposal and release to water slags Metallurgical slags Precipitation of salts 0.8 g/l Cu 1.6 g/l Zn Drainage ditchLa Lucette Sb smelter( France ) Zn smelting plant (Russia) 21
  22. 22. Potential variations of impacts after a mine closure Potential variations in impacts from hazardous mine waste after a metal mine is closedSource: BGS 22
  23. 23. Socio-economic impacts and ancient mining Abandoned facilities at the surface Sentein Pb,Zn, Ag ancient mine (France) 23
  24. 24. Socio-economic impacts and old mining sites Physical stability subsidence Slope failure Lorraine (France) 24
  25. 25. Socio-economic impacts and public safety bioaccumulation in the food chain Waste rock piles Mine effluentCarnoulés (France) 25 Uchaly (Russia)
  26. 26. Positive impacts: metals empower us 26
  27. 27. Conclusions (1) Providing metals and raw materials for the futureThe demands for both minerals and metals are expected to increase in the decades ahead (world population growth and rising standards of living…) New challenges and balanced approaches for mineral supply and environmental protection needed Society ’s expectations and the future of the mining industry require that the long-term environmental impacts of mining be adequately addressed 27
  28. 28. Conclusions (2)Protecting the environment and human health PREVENTION is the keyQ dumping sites and tailing dams management and reclamationP water management and treatmentP reduction of acid rock drainageP control of dust and gaseous emissionsP recyclingP ... 28
  29. 29. Conclusions (3) How Science and technology can help ? The example of MINEO PROJECTDevelopping more efficient and cost-effective tools basedon Earth Observation Methods for handling mining-relatedenvironmental impacts and risks at regional scales P identification, characterization and mapping of surface physical and chemical disturbances: landscape patterns = surficial indicators of processes P detailed mapping in a risk assessment perspective of sources of pollution, migration pathways, endpoints and population / ecosystems potentially at risk P definition of contamination model and monitoring programme ... 29