Mining Practices With Objective Of Sustainability


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SUSTAINABLE DEVELOPMENT - Aims at meeting the needs of present generation without adversely affecting its availability for future

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Mining Practices With Objective Of Sustainability

  1. 1. Author: Partha Das Sharma (B.Tech – Hons., in Mining Engineering) 1 Website:
  2. 2. SUSTAINABLE DEVELOPMENT Aims at meeting the needs of present generation without adversely affecting its availability for future Rate of depletion of non-renewable resources should be judicious Minimum adverse impact to the environment Maintaining equilibrium in eco-system. 2
  4. 4. PROSPECTING & EXPLORATION It is the most important exercise, to be carried out very faithfully because entire fate of future lies upon this 4
  5. 5. PROSPECTING vs. EXPLORATION Prospecting is pre- Exploration is a mining stage dynamic process & operation mainly continues during confines to subsistence of mining establishing sufficient period. It is expected evidence of mineral it should lead ahead occurrence in respect of mining operation of shape, size, for consistent quantity, quality & updating the mineral economics reserve 5
  6. 6. It also should include Identification of various litho-units occurring in & around the proposed mining site Establishing sufficient evidence of mineral occurrence in respect of shape, size, quantity, quality & economics Correct assessment of geo-technical properties of rock mass including their toxic values. 6
  7. 7. CONCEPTUAL MINING PLAN Long-term Perspective view of mining Time frame for assessing the true potentiality of area Visualization and determination of ultimate pit limit Waste disposal management Post-mining land use Ensuing mining operation are part of it. 7
  8. 8. MINE DEVELOPMENT Mode of Mining Selection of method of mining Mechanized Semi-mechanized Opencast Manual Underground Conventional Mixed Non-conventional 8
  9. 9. OPEN CAST MINING Precise assessment of optimum stripping ratio for amenability by open pit mining Determination of ultimate pit limit precisely in advance Separate removal of top soil, mine-waste Advance removal of waste to avoid any possibility of interruption in work or ore dilution/contamination 9
  10. 10. OPEN CAST MINING continued…. Proper laying of mine faces for winning of different grades simultaneously to ensure judicious blending of ROM Aiming to mine up to optimum depth Minimum mineral loss / dilution Safe, secure & energy saving haul road 10
  11. 11. UNDERGROUND MINES 1. Selection & location proper mode of entry & exit i.e. Vertical shaft Inclined Shaft Decline/Ramp Auxiliary/staple/ventilation shaft System of winding & access 11
  12. 12. UNDERGROUND MINES continued 2. Selection of proper method of work in relation to- Optimum recovery Geotechnical properties of ore & wall rocks Adequate size of openings, blocks, pillars etc & long-term sustainability Complete width of ore body is to be worked Ensure least surface damage 12
  13. 13. MINERAL CONSERVATION Waste should not be allowed to mixed with non-saleable fraction. Ground selected for waste disposal is to be proven for mineral occurrence and should be away from ultimate pit limit. Separate stacking of sub-grade mineral Judicious blending by different combination In case of underground mine, subgrade mineral is to be brought to the surface. 13
  14. 14. BENIFICIATION OPERATION All attempts are to be made for up- gradation of low-grade mineral to make it saleable fraction. Beneficiation Investigation are to be carried out Regular analysis of ‘feed’, ‘product’ & ‘tailings’ 14
  15. 15. PLANT & MACHINARY Selection of matching machinery to the mine design parameters & local conditions. Optimum utilization Time & motion study Least waiting/idle time 15
  16. 16. PLANT & MACHINARY continue.. Energy saving & conformity to emission standards Attenuation of noise at the source itself Dust suppression at the source of generation Planned preventive maintenance Minimum re-handling 16
  17. 17. BLASTING Proper Blast design Optimum utilization of blast energy Desired fragmentation Neither under break nor over break Least ground vibration Least air blast Least fly rock Least nuisance attracting public annoyance Regular scientific investigation 17
  18. 18. SOLID WASTES GENERATED MINE WASTES MILL/PLANT WASTE Large in quantity Less in quantity Mostly inert Can be toxic Large in size- Solids Fine particles-Slurry Represents in-situ Altered Product 18
  19. 19. ENVIRONMENTAL PROBLEMS Leaching & wash off - heavy metals & toxic elements -acid mine drainage Dust pollution with toxic metals Phyto-accumulation of heavy metals Effect on vegetation & aquatic eco-system, Entry into food chain Effect on landscape 19
  20. 20. WASTE DUMP DESIGN Height, area & shape with regard to the area available, topography & vegetation. Avoid Proliferation of dumps. Surfaces should be stable & resist long term erosion. Peripheral dumping, with simultaneous afforestation. Toxic waste dumps to be contoured and/or sealed to minimize water penetration. Potentially acid forming material to be sealed by inactive waste that has a buffering capacity. 20
  21. 21. WASTE DUMP DESIGN Construction of drainage to handle heavy rainfalls. Topsoil scraped out from dumpsite in advance, to be preserved, spread over surface & re- vegetated. Provision of garland drains surrounding the dumps Provision of Retaining walls/Toe walls. Completed overall out-slopes do not exceed 20 degree Provision of benches/berms. 21
  22. 22. DUMP INSTABILITIES (Long-term instability) REASON SOLUTION Due to saturation Growth of with water & permanent reduction in vegetation over strength of dump surface & material due to establishment of water action. proper drainage. 22
  23. 23. DUMP INSTABILITIES (short-term instability) REASON SOLUTION Benches, of heights not Poor material more than 10 to 15 m, strength, improper with min. berm width of heights & slope 4 m. angles. Berm to have gentle Long unbroken slope, say 0.5%, slopes produce rill & towards high-wall side, gully erosion with toe wall along periphery of dump. 23
  24. 24. Estimated relationship between the angle of dump slope and soil erosion & efficiency of re- vegetation 24
  26. 26. Management of Waste Dumps (Physical Stability) ISSUES Steep slopes Unstable surfaces Erosion Drainage Dust Generation Hazardous waste Control 26
  27. 27. Management of Waste Dumps (Physical Stability) Control Methods Site selection Peripheral dumping, Retaining walls/Toe walls Internal drains & garland drain Gentle slopes & heights Berms, with rock-lined drains Cover & secure containment of hazardous waste, Cap with soil Settling ponds Vegetation along slopes Green barriers 27
  28. 28. Management of Waste Dumps (Chemical Stability) Issues Metal leaching Seepage Acid drainage Contaminants Effects on surface and groundwater Dump design 28
  29. 29. Management of Waste Dumps (Chemical Stability) Control Methods Analyze the samples Isolation of reactive material No deterioration in groundwater Cap/enclose toxic material with inert & impervious material Control surface drainage & runoff Collect and treat effluent Cap with topsoil & vegetate Effective water management Monitor 29
  30. 30. Management of Waste Dumps (Land-use) Control Methods Issues Marketing/reuse of waste Productivity Back-filling Visual impacts Avoid dump proliferation Restore to original or Design for minimum area accepted alternative use Re-contour Establish land drainage Establish vegetation Landscaping 30
  31. 31. Management of Waste Dumps (Biological Stability) Issues Control Methods Re-vegetation Soil Fertilization/stabilization Bio-diversity Planting leguminous plants Survival of vegetation Draught resistant species Phyto-accumulation of Selection of Phyto-resistant toxic & heavy metals species Entry of toxic & heavy Successful re-vegetation with indigenous plants metals into food chain Protection for animal grazing Development of self- Monitoring for soil quality sustaining plant Congenial environment for community wildlife, with fodder & water Forestry 31
  32. 32. TOP-SOIL MANAGEMENT Recovery is essential for rehabilitation work. Sooner it is reused the better the results will be. Soil Stacks: Low heights, Should not get washed off Leguminous plants are to be cultivated In areas of poor soils, nutrient levels is low Fertilizer application is soil cheaper than soil stabilizers Single application will suffice in all areas except those prone to high soil leaching - eg over tailings 32
  33. 33. TAILING IMPOUNDMENT Design requirements of dam & impoundment: Impoundment to be competent to support Not to be located in recharge zone, establishing hydraulic with aquifer Relatively impervious, otherwise an impervious layer/dyke to be provided at bottom Foundation soil of the dam and the dam it self be competent to support & relatively impervious, otherwise internal drainage to be provided in side the dam Dam should have stable slopes- downstream slopes 1:3 33
  34. 34. Design requirements of dam & impoundment Adequate drainage features to be provided As much as water must be re-cycled Conduits from decant towers passing below the dam be avoided A floating or moveable pump hose located on the shore is better for water reclamation At each stage, dam raising should be fast to stay ahead of the rising tailings in the pond. 34
  35. 35. 35
  36. 36. Management of Tailing Impoundment (Physical Stability) Control Methods Site capacity & impervious Issues Dam erected by competent rock Dam wall stability & foundation Spillway/Adequate freeboard –1m Dust generation Decant towers or floating pump Erosion & Sediment deposit Diversion of runoff to out side Dam drainage & Seepage Stage-wise raising to be fast Control on Phreatic line Tailing disposal Overtopping of dam Downstream Construction Earthquakes Final re-profile, Instrumentation Access and security Cap with soil & vegetate Plug intakes & decants 36
  37. 37. Management of Tailing Impoundment (Chemical Stability) Control Methods Issues Leaching tests Changes in tailings Non-reactive material in dam geochemistry wall Metal leaching Impervious layers- seepage Acid drainage Establish drainage within dam Mill reagents Control reactions Dam structure Divert run-off Groundwater- seepage effect Collect and treat effluent past the dam & from impoundment base Acceptable water quality in downstream Surface water management Monitor 37
  38. 38. Management of Tailing Impoundment (Land- use) Control Methods Issues Re-contour to mach Productivity surrounding landscape Visual impacts Provide soil capping Restore to accepted Provide sedimentation alternative use tank Establish vegetation 38
  39. 39. Management of Tailing Impoundment (Biological Stability) Control Methods Issues Re-vegetation Soil stabilization Bio-diversity Planting leguminous plants Survival of vegetation Indigenous species growth Draught resistant species Phyto-accumulation of Selection of species resistant to toxic & heavy metals phyto-accumulation & concentration of toxic elements Entry of toxic & heavy Protection of re-vegetated area metals into food chain against animal grazing Monitoring for soil quality & for phyto-accumulation 39
  40. 40. WATER QUALITY Quantitative & Qualitative studies, for Surface & Ground Water characteristics Available Site Water Sources Catchments area Water Management & upstream pollution sources Maximum & Lean Rainfall Runoff rate at Peak Rainfall Potable Water Supply Sources, Quality & Quantity Domestic & Process Waste Water discharge Discharge points, Quality & Quantity 40
  41. 41. WATER BALANCE AT SITE Lean season water availability Source tapped with competing users (River, Lake, Ground, Public supply) Changes observed in quality & quantity of ground water Present recharging & extraction details Quantum of surface waste water to be released with treatment details Quantum of quality of water in receiving body, before & after disposal of waste /effluent Quantum of waste/effluent water released on land & type of land 41
  42. 42. Water balance diagram Schematic diagram linking up flow of water to & from the facilities, Showing water supply source (s), Water discharge points), Evaporation areas & potential seepage points, with step wise indication of flow rates, in cum/day & quality, into & out of facility 42
  43. 43. Management of Water Quality (Physical Stability) Control Methods Issues Remove/restore unwanted Erosion, wash-off & structures, Fill in ditches sediment deposit Plug intakes & decants Blockage in natural flow Upgrade flood design Sewage & effluent Reinstall pre-mining drainage treatment plants & Dispose plants & plant sludge sludge Discharge of drainage Install check dams/settling pond Structural Safety & Develop re-charge flood capacity wells/holes Intrusion of sea water Re-vegetate Water balance, Install pre-mining water balance for mine area recharge 43
  44. 44. Management of Water Quality (Chemical Stability) Control Methods Issues Prevent/remove contamination of surface &groundwater with: -Acid drainage Contamination of -Leaching of toxic metals surface and /or Install new settling ponds groundwater Erect stopping or flood the pit Acid drainage Drainage - treat & discharge Leaching of toxic metals Install barriers/grout curtains Establish phyto-accumulant vegetation Monitor 44
  45. 45. Management of Water Quality (Land-use) Control Methods Issues Avoid interruption of water supply Interruption of water Establish erosion-resistant supply in catchment drainage area Restore drainage patterns or Productivity of land establish effective drainage alternatives Install retaining walls Sediment deposition Stabilize and maintain dam (Nalla sediments) or breach Return to appropriate Establish vegetation land use Establish effective rehabilitation 45
  46. 46. Management of Air Quality (Physical & Chemical Stability & Land-use) Control Methods Cap toxic & hazardous waste Issues Remove or prevent Wind Erosion contamination Effect on vegetation Land fill & capping Pollution of air with toxic Establish vegetation substance Contamination of surface Develop thick green barriers Productivity of land Monitor Establish erosion-resistant Structures Return to appropriate land use or establish alternatives 46
  47. 47. Monitoring of Water & Air Quality To demonstrate remedial/ restoration work is successful. To meet closure objectives & performance criteria. To compare results with earlier monitoring data. Monitoring for dry season, as per IBM/MoEF norms. Climactic data also to be coupled 47
  48. 48. RECLAMATION & REHABILITATION Creation of adequate green belt in and around mining lease area It gives a green curtain is to be set against all scars i.e. excavation, dumps etc and improves aesthetic sense of the area It effectively arrests all the dust generated from mines It effectively attenuate unpleasant noise Lessens the adverse effect of green house gas emission 48
  49. 49. RECLAMATION & REHABILITATION continued…. Incase of availability of mine waste, voids are to be filled back & efforts are to be made to bring them near original shape Incase of partial availability of waste, possibility of part reclamation is to be thought. Remaining voids can be converted as water reservoir 49
  50. 50. RECLAMATION & REHABILITATION continued…. Possibility of filling by fly ash or other waste material available nearby is also to be thought but a prior study thereof is also to be undertaken for any apprehended adverse impact on water regime In case of shallow excavations, quarry floor plantation is to be undertaken along with adequate drainage arrangement 50
  51. 51. RECLAMATION & REHABILITATION continued…. Incase of arid regions, converting the pits as water reservoir is best post mining land use. But its slope should be adequate & should also act as shield against drowning. Incase of hilly terrain dense plantation is to be undertaken on finalized bench. 51
  52. 52. Conclusion: Mankind should learn the correct way of enjoying the natural wealth from the Honeybee as they continue to collect Honey from the flowers without causing any detrimental impact or deformation to the nature’s beautiful gifts. 52