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Heap leach op and water footprint


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HeapLeach y Huella Hídrica
presentado en Congreso Heap Leaching, Lima 2016

Published in: Engineering
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Heap leach op and water footprint

  1. 1. Heap Leaching and Water Footprint Augusto Chung Ching, Rio Alto Mining Oswaldo Tovar, Ingeniería de Recursos SRL
  2. 2. Overview • Understand importance of water • Definition of Water footprint • Types of water • Water balance • Benchmark • Challenges • Proposal • Conclusions
  3. 3. Heap Leach & Water Footprint • Understand your water in the mining industry: • Communicating water use is fundamental to maintaining social license to operate • Water accounting is to focus on reducing your own consumption • Water storage in heaps (iceberg) • Solution inventory (water and dissolved metals) • Permanent vs On-off pad • Water problems with communities and regulators • We license, take water, use, storage, recirculate as much as possible, evaporate, treat, return to body water
  4. 4. Water Footprint • Water footprint is the volume of fresh water used to produce a product summed over the various steps of the supply chain • Water footprint goes on to: – Quantity of the volume – Consider the type of water used – Consider when and where the water is used
  5. 5. Examples of Water Footprint for… • 1 cup of coffee, 150 liters of water • 1 kg refined sugar, 1500 liters • 1 kg of tomatoes, 180 liters • 1 sheet of A4 paper, 10 liters • 1 kg of meat, 15,500 liters • 1 kg of cotton, 11,000 liters • Treatment of 1 ton of Cu ore, 1050 liters • Treatment of 1 ton of Au ore, 1250 liters
  6. 6. Type of Water used • Green water = rain water • Blue water = surface water, river, lakes, underground water • Gray water = retreated water, polluted water
  7. 7. Green Water Green Water (rain) Impoundment Incorporated into the heap or process Evaporated
  8. 8. Blue Water Blue Water (river, lake, Underground) Evaporated volume Returned to another catchment area or the sea Incorporated to heap or process
  9. 9. Gray Water Gray Water (volume of polluted water) Bypassed Treated and/or released into the water body Consumed (incorporated to heap or process)
  10. 10. Water Footprint • Measures fresh water appropriation • Actual, locally specific values • Always referring to full supply-chain • Focus on reducing own water footprint
  11. 11. Ground and surface water rain Runoff at field level Non-production related evapotranspiration Soil and vegetation HEAP process Rivers, lakes abstraction Return flow farms Production-related evapotranspiration Water-contained In products GREEN WF evaporation Water contained in products Water to other catchment BLUE WF GRAY WF Catchment area
  12. 12. Evapotranspiration • Evaporation is the process where liquid water is converted into vapor water – Evaporation is predominant when crop is small and water loss is primarily by soil evaporation, or under high frequency wetting when soil evaporation and evaporation of free water from plant surfaces can be high • Evapotranspiration is vaporization of liquid water and plants / vapor removal from the atmosphere – ET is an energy controlled process requiring the conversion of available radiation energy (sunshine) and sensible energy (heat contained in the air) into latent energy (energy stored in water vapor)
  13. 13. Some Global water footprint • China, 2900 liters / person / day • India, 3000 liters / person / day • Indonesia, 3100 liters / person / day • Germany, 3900 liters / person / day • Saudi Arabia, 5100 liters / person / day • Australia, 6300 liters / person / day • USA, 7800 liters / person / day • Mongolia, 1000 liters / person / day
  14. 14. Water Footprint • ISO 14046:2012 “amount of all water flows –controlled and uncontrolled-consumed, used, evaporated, or contaminated to produce an output unit in” m3/lb.Cu: for Cu leaching m3/oz.Au: for Au leaching m3/ton.Concentrate: for crush-mill-flotation Perú included this KPI in production statistics since 2005
  15. 15. Benchmark • We have to get agree for a common reference: – m3/input (m3/tpd) – m3/output – m3/area – m3/workforce • Rates of consumption in: USA (copper mines in Arizona) Source: Department of Mines and Mineral Resources of Arizona m3/ton Cu fino 198 544 223 54 200 393 47
  16. 16. Benchmark • Chile’ consumption Source: Ministerio de Obras Públicas, Dirección General de Aguas, División de Estudios y Planificación
  17. 17. Benchmark • Perú’ consumption Source: Ministerio de Energía y Minas. Datos de Agosto 2010
  18. 18. Challenges • Maximize recovery/revenues • Minimize water usage in the whole process by zero discharge. • Which means: – Eliminate unnecessary inputs – Ability to predict ionic concentrations en all flows to avoid incrustations – Ability to recycle 100% – Identify sources of contamination in the process
  19. 19. Proposal Commitment to optimization Philosophy of Water Management (“In Source Reduction”) Comprehensive Survey (ionic) Alternatives Analysis and Comparison Decision Making Output: 1. Block diagram and mass balance 2. Table of metallurgical parameters and simulation criteria for each case 3. Alternatives studied and simulated in Matlab-Simulink 4. PFDs 5. OPEX & CAPEX for decision making 6. Risks and Opportunities for decision making 7. Execution plan and schedule for next stages
  20. 20. Conclusions • Standardization is pending task • Operations in desert (Chile, Nevada) are benchmark. Let’s support them and then rely on their experience • Space for improvement in data management. • We need to internalize that water is a common economic resource. • This is not an only water/hydraulic problem. We have to understand about metallurgic, kinetics, catalyst, cycles and optimize not only recovery but also water usage.
  21. 21. Q & A
  22. 22. Questions & Answers