Tac dong moi truong 3


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Tac dong moi truong 3

  1. 1. Potential Environmental Problems A. Mining operation itself – Disposal of a large amount of rock and waste – Noise – Dust Beneficiation Smelting and refining
  2. 2. From Underground Mining Subsidence – Block/caving – Room and pillar – Salt mining
  3. 3. Subsidence in rancher’s field
  4. 4. Subsidence from Pb-Zn mining
  5. 5. From Underground Acid Mine Drainage – FeS minerals in coal – Sulphide deposits – Acidic streams can pick up heavy elements and transport them
  6. 6. Rock that has acid forming material
  7. 7. Drainage
  8. 8. Acid and open pitsBerkley Pit
  9. 9. Other problems with open pits Very large holes Pit slopes steep and not stable. Cannot be maintained May fill with water Strip coal mines –loss of top soil in past – Now smoothed out and top soil added
  10. 10. Disposal of Waste Rock More problematic for open pit than underground Waste rock piles have steep angle of repose and thus may not be stable Bingham in its hay day produced 400,000 tons of waste rock per DAY!
  11. 11. Tailings ponds From concentrating usually have high pH – At Bingham acid waters mixed with tailings water to neutralize Different metals have different problems
  12. 12. Problems with Smelting/Roasting Air: SO2 and CO2 and particulate matter Noranda Quebec used to have the highest single point source of SO2 in the world. It may have been surpassed. CN (Au); NaOH and F (Al); solvents (electrotwinning); heavy metals; oil and grease
  13. 13. Environmental Impact Environmental impact – From mineral exploration and testing – From mineral mining – From mineral resources refining – From mining waste disposal
  14. 14. Environment Impact of Mineral Development The impact depends upon many factors: – Mining procedures – Hydrologic conditions – Climate factors – Types of rocks and soils – Topography Also population: NIMBY
  15. 15. Impact of Mineral Exploration and Testing Mineral exploration and testing – Surface mapping, geochemical, geophysical, and remote-sensing data collection – Test drilling Impact – Generally minimal impact – More planning and care needed for sensitive areas (arid, wetlands, and permafrost areas)
  16. 16. Impact of Mineral Extraction and Processing (1)General impact Direct impact on land, water, air, and biological environment Indirect impact on the environment: Topographic effect, transportation of materials, etc. Impact on social environment: Increased demands for housing and services
  17. 17. Impact of Mineral Extraction and Processing (2) Impact from mining operations – Land disturbances;Berk eley Pit.km e.g., z – Waste from mines: 40% of the mining area for waste disposal, mining waste 40% of all solid wastes; e.g., , – Special mining, e.g., chemical leaching from gold mining; e.g., – Mining acid drainage, during mining and post-mining; e.g., New World district Chico placer.kmz ASARCO tailings.kmz Golden Sunlight.kmz
  18. 18. Mclaren tailings.kmz
  19. 19. Impact of Mineral Extraction and Processing (4) Water pollution – Trace elements leaching out into water, such as Cd, Co, Cu, Pb, Mo, Zn – Flooding of abandoned mines, oxidation of sulfide ores = sulfuric acid – Acid mine drainage from tailings
  20. 20. Pollution of water from mining
  21. 21. Minimizing the Impact of Mining (1) Knowledge and technology transfer: developed countries to developing countries Environmental Regulations: Forbid bad mining practices, Clean Air Act, and on- and offsite treatment of wastes Land reclamation: About 50% of land used in mining industry reclaimed Use of new biotechnology in mining: Bio-oxidation, bioleaching, biosorption, genetic engineering
  22. 22. Minimizing the Impact of Mining (2)Figure 14.14
  23. 23. Recycling Mineral Resources (1) Why recycle? Consider the impact of the wastes – Toxic to humans – Dangerous to natural ecosystems – Degradation of air, water, and soil – Use of land for disposal – Aesthetically undesirable
  24. 24. Recycling Mineral Resources (2) Waste contains recyclable materials Saves energy, money, land, raw mineral resources from more mining Saves energy and money when recycling instead of refining raw ore materials Recycling has been proven to be profitable and workable
  25. 25. Recycling Mineral Resources (3) Most-recycled metals: Iron and steel, 90% by weight One-third as much energy needed to produce steel from recycled scrap as from original ore More than $40 billion produced from recycled metals in 1998 Other recycled metals: Lead (63%), aluminum (38%), and copper (36%)
  26. 26. Life cycle of a metal resource
  27. 27. Minerals and Sustainability Sustainability: long-term strategy for consuming the resources Find an alternative material for the metal, e.g., glass fiber cable for copper wires Use raw materials more efficiently More R&D on innovative substitutes or ways to keep the R/C ratio, a solution to the depletion of nonrenewable resources
  28. 28. Applied and Critical Thinking Topics Considering the fact that mineral resources are nonrenewable, do you believe that technology will eventually help to meet the growing demand for mineral resources? If yes, explain. Biotechnology shows the potential for cleaner minerals extraction and waste disposal. Will biotechnology bring about any environmental problems? What types of environmental impact would occur if we increasingly extract more mineral resources from the seafloor?