technologyComment of gold mine operation and refining (SE): OPEN PIT MINING: The ore is mined in four steps: drilling, blasting, loading and hauling. In the case of a surface mine, a pattern of holes is drilled in the pit and filled with explosives. The explosives are detonated in order to break up the ground so large shovels or front-end loaders can load it into haul trucks. ORE AND WASTE HAULAGE: The haul trucks transport the ore to various areas for processing. The grade and type of ore determine the processing method used. Higher-grade ores are taken to a mill. Lower grade ores are taken to leach pads. Some ores may be stockpiled for later processing. HEAP LEACHING: The ore is crushed or placed directly on lined leach pads where a dilute cyanide solution is applied to the surface of the heap. The solution percolates down through the ore, where it leaches the gold and flows to a central collection location. The solution is recovered in this closed system. The pregnant leach solution is fed to electrowinning cells and undergoes the same steps as described below from Electro-winning. ORE PROCESSING: Milling: The ore is fed into a series of grinding mills where steel balls grind the ore to a fine slurry or powder. Oxidization and leaching: Some types of ore require further processing before gold is recovered. In this case, the slurry is pressure-oxidized in an autoclave before going to the leaching tanks or a dry powder is fed through a roaster in which it is oxidized using heat before being sent to the leaching tanks as a slurry. The slurry is thickened and runs through a series of leaching tanks. The gold in the slurry adheres to carbon in the tanks. Stripping: The carbon is then moved into a stripping vessel where the gold is removed from the carbon by pumping a hot caustic solution through the carbon. The carbon is later recycled. Electro-winning: The gold-bearing solution is pumped through electro-winning cells or through a zinc precipitation circuit where the gold is recovered from the solution. Smelting: The gold is then melted in a furnace at about 1’064°C and poured into moulds, creating doré bars. Doré bars are unrefined gold bullion bars containing between 60% and 95% gold. References: Newmont (2004) How gold is mined. Newmont. Retrieved from http://www.newmont.com/en/gold/howmined/index.asp technologyComment of gold production (US): OPEN PIT MINING: The ore is mined in four steps: drilling, blasting, loading and hauling. In the case of a surface mine, a pattern of holes is drilled in the pit and filled with explosives. The explosives are detonated in order to break up the ground so large shovels or front-end loaders can load it into haul trucks. UNDERGROUND MINING: Some ore bodies are more economically mined underground. In this case, a tunnel called an adit or a shaft is dug into the earth. Sort tunnels leading from the adit or shaft, called stopes, are dug to access the ore. The surface containing the ore, called a face, is drilled and loaded with explosives. Following blasting, the broken ore is loaded onto electric trucks and taken to the surface. Once mining is completed in a particular stope, it is backfilled with a cement compound. BENEFICIATION: Bald Mountain Mines: The ore treatment method is based on conventional heap leaching technology followed by carbon absorption. The loaded carbon is stripped and refined in the newly commissioned refinery on site. Water is supplied by wells located on the mine property. Grid power was brought to Bald Mountain Mine in 1996. For this purpose, one 27-kilometre 69 KVA power line was constructed from the Alligator Ridge Mine substation to the grid. Golden Sunlight Mines: The ore treatment plant is based on conventional carbon-in-pulp technology, with the addition of a Sand Tailings Retreatment (STR) gold recovery plant to recover gold that would otherwise be lost to tailings. The STR circuit removes the heavier gold bearing pyrite from the sand portion of the tailings by gravity separation. The gold is refined into doré at the mine. Tailing from the mill is discharged to an impoundment area where the solids are allowed to settle so the water can be reused. A cyanide recovery/destruction process was commissioned in 1998. It eliminates the hazard posed to wildlife at the tailings impoundment by lowering cyanide concentrations below 20 mg/l. Fresh water for ore processing, dust suppression, and fire control is supplied from the Jefferson Slough, which is an old natural channel of the Jefferson River. Ore processing also uses water pumped from the tailings impoundment. Pit water is treated in a facility located in the mill complex prior to disposal or for use in dust control. Drinking water is made available by filtering fresh water through an on-site treatment plant. Electric power is provided from a substation at the south property boundary. North-Western Energy supplies electricity the substation. Small diesel generators are used for emergency lighting. A natural gas pipeline supplies gas for heating buildings, a crusher, air scrubber, boiler, carbon reactivation kiln, and refining furnaces. Cortez Mine: Three different metallurgical processes are employed for the recovery of gold. The process used for a particular ore is determined based on grade and metallurgical character of that ore. Lower grade oxide ore is heap leached, while higher-grade non-refractory ore is treated in a conventional mill using cyanidation and a carbon-in-leach (“CIL”) process. When carbonaceous ore is processed by Barrick, it is first dry ground, and then oxidized in a circulating fluid bed roaster, followed by CIL recovery. In 2002 a new leach pad and process plant was commissioned; this plant is capable of processing 164 million tonnes of heap leach ore over the life of the asset. Heap leach ore production is hauled directly to heap leach pads for gold recovery. Water for process use is supplied from the open pit dewatering system. Approximately 90 litres per second of the pit dewatering volume is diverted for plant use. Electric power is supplied by Sierra Pacific Power Company (“SPPC”) through a 73 kilometre, 120 kV transmission line. A long-term agreement is in place with SPPC to provide power through the regulated power system. The average power requirement of the mine is about 160 GWh/year. REFINING: Wohlwill electrolysis. It is assumed that the gold doré-bars from both mines undergo the treatment of Wohlwill electrolysis. This process uses an electrolyte containing 2.5 mol/l of HCl and 2 mol/l of HAuCl4 acid. Electrolysis is carried out with agitation at 65 – 75 °C. The raw gold is intro-duced as cast anode plates. The cathodes, on which the pure gold is deposited, were for many years made of fine gold of 0.25 mm thickness. These have now largely been replaced by sheet titanium or tantalum cathodes, from which the thick layer of fine gold can be peeled off. In a typical electrolysis cell, gold anodes weighing 12 kg and having dimensions 280×230×12 mm (0.138 m2 surface) are used. Opposite to them are conductively connected cathode plates, arranged by two or three on a support rail. One cell normally contains five or six cathode units and four or five anodes. The maximum cell voltage [V] is 1.5 V and the maximum anodic current density [A] 1500 A/m2. The South African Rand refinery gives a specific gold production rate of 0.2 kg per hour Wohlwill electrolysis. Assuming a current efficiency of 95% the energy consumption is [V] x [A] / 0.2 [kg/h] = 1.63 kWh per kg gold refined. No emissions are assumed because of the purity and the high value of the material processed. The resulting sludge contains the PGM present in the electric scrap and is sold for further processing. OTHER MINES: Information about the technology used in the remaining mines is described in the References. WATER EMISSIONS: Water effluents are discharged into rivers. References: Auerswald D. A. and Radcliffe P. H. (2005) Process technology development at Rand Refinery. In: Minerals Engineering, 18(8), pp. 748-753, Online-Version under: http://dx.doi.org/10.1016/j.mineng.2005.03.011. Newmont (2004) How gold is mined. Newmont. Retrieved from http://www.newmont.com/en/gold/howmined/index.asp Renner H., Schlamp G., Hollmann D., Lüschow H. M., Rothaut J., Knödler A., Hecht C., Schlott M., Drieselmann R., Peter C. and Schiele R. (2002) Gold, Gold Alloys, and Gold Compounds. In: Ullmann's Encyclopedia of Industrial Chemistry. Online version, posting date: September 15, 2000 Edition. Wiley-Interscience, Online-Version under: http://dx.doi.org/10.1002/14356007.a12_ 499. Barrick (2006b) Environment: Performance Tables from http://www.barrick. com/Default.aspx?SectionID=8906c4bd-4ee4-4f15-bf1b-565e357c01e1& LanguageId=1 Newmont (2005b) Now & Beyond: Sustainability Reports. Newmont Mining Corporation. Retrieved from http://www.newmont.com/en/social/reporting/ index.asp technologyComment of gold production (CA): OPEN PIT MINING: The ore is mined in four steps: drilling, blasting, loading and hauling. In the case of a surface mine, a pattern of holes is drilled in the pit and filled with explosives. The explosives are detonated in order to break up the ground so large shovels or front-end loaders can load it into haul trucks. UNDERGROUND MINING: Some ore bodies are more economically mined underground. In this case, a tunnel called an adit or a shaft is dug into the earth. Sort tunnels leading from the adit or shaft, called stopes, are dug to access the ore. The surface containing the ore, called a face, is drilled and loaded with explosives. Following blasting, the broken ore is loaded onto electric trucks and taken to the surface. Once mining is completed in a particular stope, it is backfilled with a cement compound. ORE AND WASTE HAULAGE: The haul trucks transport the ore to various areas for processing. The grade and type of ore determine the processing method used. Higher-grade ores are taken to a mill. Lower grade ores are taken to leach pads. Some ores may be stockpiled for later processing. BENEFICIATION: In the Porcupine Mines, gold is recovered using a combination of gravity concentration, milling and cyanidation techniques. The milling process consists of primary crushing, secondary crushing, rod/ball mill grinding, gravity concentration, cyanide leaching, carbon-in-pulp gold recovery, stripping, electrowinning and refining. In the Campbell Mine, the ore from the mine, after crushing and grinding, is processed by gravity separation, flotation, pressure oxidation, cyanidation and carbon-in-pulp process followed by electro-winning and gold refining to doré on site. The Musselwhite Mine uses gravity separation, carbon in pulp, electro¬winning and gold refining to doré on site. REFINING: Wohlwill electrolysis. It is assumed that the gold doré-bars from both mines undergo the treatment of Wohlwill electrolysis. This process uses an electrolyte containing 2.5 mol/l of HCl and 2 mol/l of HAuCl4 acid. Electrolysis is carried out with agitation at 65 – 75 °C. The raw gold is intro-duced as cast anode plates. The cathodes, on which the pure gold is deposited, were for many years made of fine gold of 0.25 mm thickness. These have now largely been replaced by sheet titanium or tantalum cathodes, from which the thick layer of fine gold can be peeled off. In a typical electrolysis cell, gold anodes weighing 12 kg and having dimensions 280×230×12 mm (0.138 m2 surface) are used. Opposite to them are conductively connected cathode plates, arranged by two or three on a support rail. One cell normally contains five or six cathode units and four or five anodes. The maximum cell voltage [V] is 1.5 V and the maximum anodic current density [A] 1500 A/m2. The South African Rand refinery gives a specific gold production rate of 0.2 kg per hour Wohlwill electrolysis. Assuming a current efficiency of 95% the energy consumption is [V] x [A] / 0.2 [kg/h] = 1.63 kWh per kg gold refined. No emissions are assumed because of the purity and the high value of the material processed. The resulting sludge contains the PGM present in the electric scrap and is sold for further processing. WATER EMISSIONS: Effluents are discharged into the ocean. REFERENCES: Newmont (2004) How gold is mined. Newmont. Retrieved from http://www.newmont.com/en/gold/howmined/index.asp Renner H., Schlamp G., Hollmann D., Lüschow H. M., Rothaut J., Knödler A., Hecht C., Schlott M., Drieselmann R., Peter C. and Schiele R. (2002) Gold, Gold Alloys, and Gold Compounds. In: Ullmann's Encyclopedia of Industrial Chemistry. Online version, posting date: September 15, 2000 Edition. Wiley-Interscience, Online-Version under: http://dx.doi.org/10.1002/14356007.a12_ 499. Auerswald D. A. and Radcliffe P. H. (2005) Process technology development at Rand Refinery. In: Minerals Engineering, 18(8), pp. 748-753, Online-Version under: http://dx.doi.org/10.1016/j.mineng.2005.03.011. technologyComment of gold production (AU): OPEN PIT MINING: The ore is mined in four steps: drilling, blasting, loading and hauling. In the case of a surface mine, a pattern of holes is drilled in the pit and filled with explosives. The explosives are detonated in order to break up the ground so large shovels or front-end loaders can load it into haul trucks. UNDERGROUND MINING: Some ore bodies are more economically mined underground. In this case, a tunnel called an adit or a shaft is dug into the earth. Sort tunnels leading from the adit or shaft, called stopes, are dug to access the ore. The surface containing the ore, called a face, is drilled and loaded with explosives. Following blasting, the broken ore is loaded onto electric trucks and taken to the surface. Once mining is completed in a particular stope, it is backfilled with a cement compound. ORE AND WASTE HAULAGE: The haul trucks transport the ore to various areas for processing. The grade and type of ore determine the processing method used. Higher-grade ores are taken to a mill. Lower grade ores are taken to leach pads. Some ores may be stockpiled for later processing. LEACHING: The ore is crushed or placed directly on lined leach pads where a dilute cyanide solution is applied to the surface of the heap. The solution percolates down through the ore, where it leaches the gold and flows to a central collection location. The solution is recovered in this closed system. The pregnant leach solution is fed to electrowinning cells and undergoes the same steps as described below from Electro-winning. ORE PROCESSING: Milling: The ore is fed into a series of grinding mills where steel balls grind the ore to a fine slurry or powder. Oxidization and leaching: Some types of ore require further processing before gold is recovered. In this case, the slurry is pressure-oxidized in an autoclave before going to the leaching tanks or a dry powder is fed through a roaster in which it is oxidized using heat before being sent to the leaching tanks as a slurry. The slurry is thickened and runs through a series of leaching tanks. The gold in the slurry adheres to carbon in the tanks. Stripping: The carbon is then moved into a stripping vessel where the gold is removed from the carbon by pumping a hot caustic solution through the carbon. The carbon is later recycled. Electro-winning: The gold-bearing solution is pumped through electro-winning cells or through a zinc precipitation circuit where the gold is recovered from the solution. Smelting: The gold is then melted in a furnace at about 1’064°C and poured into moulds, creating doré bars. Doré bars are unrefined gold bullion bars containing between 60% and 95% gold. REFINING: Wohlwill electrolysis. It is assumed that the gold doré-bars from both mines undergo the treatment of Wohlwill electrolysis. This process uses an electrolyte containing 2.5 mol/l of HCl and 2 mol/l of HAuCl4 acid. Electrolysis is carried out with agitation at 65 – 75 °C. The raw gold is intro-duced as cast anode plates. The cathodes, on which the pure gold is deposited, were for many years made of fine gold of 0.25 mm thickness. These have now largely been replaced by sheet titanium or tantalum cathodes, from which the thick layer of fine gold can be peeled off. In a typical electrolysis cell, gold anodes weighing 12 kg and having dimensions 280×230×12 mm (0.138 m2 surface) are used. Opposite to them are conductively connected cathode plates, arranged by two or three on a support rail. One cell normally contains five or six cathode units and four or five anodes. The maximum cell voltage [V] is 1.5 V and the maximum anodic current density [A] 1500 A/m2. The South African Rand refinery gives a specific gold production rate of 0.2 kg per hour Wohlwill electrolysis. Assuming a current efficiency of 95% the energy consumption is [V] x [A] / 0.2 [kg/h] = 1.63 kWh per kg gold refined. No emissions are assumed because of the purity and the high value of the material processed. The resulting sludge contains the PGM present in the electric scrap and is sold for further processing. WATER EMISSIONS: Water effluents are discharged into rivers. REFERENCES: Newmont (2004) How gold is mined. Newmont. Retrieved from http://www.newmont.com/en/gold/howmined/index.asp Renner H., Schlamp G., Hollmann D., Lüschow H. M., Rothaut J., Knödler A., Hecht C., Schlott M., Drieselmann R., Peter C. and Schiele R. (2002) Gold, Gold Alloys, and Gold Compounds. In: Ullmann's Encyclopedia of Industrial Chemistry. Online version, posting date: September 15, 2000 Edition. Wiley-Interscience, Online-Version under: http://dx.doi.org/10.1002/14356007.a12_ 499. Auerswald D. A. and Radcliffe P. H. (2005) Process technology development at Rand Refinery. In: Minerals Engineering, 18(8), pp. 748-753, Online-Version under: http://dx.doi.org/10.1016/j.mineng.2005.03.011. technologyComment of gold production (TZ): The mining of ore from open pit and underground mines is considered. technologyComment of gold refinery operation (ZA): REFINING: The refinery, which provides a same day refining service, employs the widely used Miller Chlorination Process to upgrade the gold bullion it receives from mines to at least 99.50% fine gold, the minimum standard required for gold sold on the world bullion markets. It also employs the world’s leading silver refining technology. To further refine gold and silver to 99.99% the cost-effective once-through Wohlwill electrolytic refining process is used. MILLER CHLORINATION PROCESS: This is a pyrometallurgical process whereby gold dore is heated in furnace crucibles. The process is able to separate gold from impurities by using chlorine gas which is added to the crucibles once the gold is molten. Chlorine gas does not react with gold but will combine with silver and base metals to form chlorides. Once the chlorides have formed they float to the surface as slag or escape as volatile gases. The surface melt and the fumes containing the impurities are collected and further refined to extract the gold and silver. This process can take up to 90 minutes produces gold which is at least 99.5% pure with silver being the main remaining component. This gold can be cast into bars as 99.5% gold purity meets the minimum London Good Delivery. However some customers such as jewellers and other industrial end users require gold that is almost 100% pure, so further refining is necessary. In this case, gold using the Miller process is cast into anodes which are then sent to an electrolytic plant. The final product is 99.99% pure gold sponge that can then be melted to produce various end products suited to the needs of the customer. WOHLWILL PROCESS - The electrolytic method of gold refining was first developed by Dr. Emil Wohlwill of Norddeutsche Affinerie in Hamburg in 1874. Dr. Wohlwill’s process is based on the solubility of gold but the insolubility of silver in an electrolyte solution of gold chloride (AuCl3) in hydrochloric acid. Figure below provide the overview of the refining process (source Rand Refinery Brochure) imageUrlTagReplace7f46a8e2-2df0-4cf4-99a8-2878640be562 Emissions includes also HCl to air: 7.48e-03 Calculated from rand refinery scrubber and baghouse emmission values Metal concentrators, Emmision report 2016 http://www.environmentalconsultants.co.za/wp-content/uploads/2016/11/Appendix-D1.pdf technologyComment of gold refinery operation (RoW): REFINING: The refinery, which provides a same day refining service, employs the widely used Miller Chlorination Process to upgrade the gold bullion it receives from mines to at least 99.50% fine gold, the minimum standard required for gold sold on the world bullion markets. It also employs the world’s leading silver refining technology. To further refine gold and silver to 99.99% the cost-effective once-through Wohlwill electrolytic refining process is used. MILLER CHLORINATION PROCESS: This is a pyrometallurgical process whereby gold dore is heated in furnace crucibles. The process is able to separate gold from impurities by using chlorine gas which is added to the crucibles once the gold is molten. Chlorine gas does not react with gold but will combine with silver and base metals to form chlorides. Once the chlorides have formed they float to the surface as slag or escape as volatile gases. The surface melt and the fumes containing the impurities are collected and further refined to extract the gold and silver. This process can take up to 90 minutes produces gold which is at least 99.5% pure with silver being the main remaining component. This gold can be cast into bars as 99.5% gold purity meets the minimum London Good Delivery. However some customers such as jewellers and other industrial end users require gold that is almost 100% pure, so further refining is necessary. In this case, gold using the Miller process is cast into anodes which are then sent to an electrolytic plant. The final product is 99.99% pure gold sponge that can then be melted to produce various end products suited to the needs of the customer. WOHLWILL PROCESS - The electrolytic method of gold refining was first developed by Dr. Emil Wohlwill of Norddeutsche Affinerie in Hamburg in 1874. Dr. Wohlwill’s process is based on the solubility of gold but the insolubility of silver in an electrolyte solution of gold chloride (AuCl3) in hydrochloric acid. Figure below provide the overview of the refining process (source Rand Refinery Brochure) imageUrlTagReplace7f46a8e2-2df0-4cf4-99a8-2878640be562 Emissions includes also HCl to air: 7.48e-03 Calculated from rand refinery scrubber and baghouse emmission values Metal concentrators, Emmision report 2016 http://www.environmentalconsultants.co.za/wp-content/uploads/2016/11/Appendix-D1.pdf technologyComment of gold-silver mine operation with refinery (PG): OPEN PIT MINING: The ore is mined in four steps: drilling, blasting, loading and hauling. In the case of a surface mine, a pattern of holes is drilled in the pit and filled with explosives. The explosives are detonated in order to break up the ground so large shovels or front-end loaders can load it into haul trucks. ORE AND WASTE HAULAGE: The haul trucks transport the ore to various areas for processing. The grade and type of ore determine the processing method used. Higher-grade ores are taken to a mill. Lower grade ores are taken to leach pads. Some ores may be stockpiled for later processing. HEAP LEACHING: The recovery processes of the Misima Mine are cyanide leach and carbon in pulp (CIP). The ore is crushed or placed directly on lined leach pads where a dilute cyanide solution is applied to the surface of the heap. The solution percolates down through the ore, where it leaches the gold and flows to a central collection location. The solution is recovered in this closed system. The pregnant leach solution is fed to electrowinning cells and undergoes the same steps as described below from Electro-winning. ORE PROCESSING: Milling: The ore is fed into a series of grinding mills where steel balls grind the ore to a fine slurry or powder. Oxidization and leaching: The recovery process in the Porgera Mine is pressure oxidation and cyanide leach. The slurry is pressure-oxidized in an autoclave before going to the leaching tanks or a dry powder is fed through a roaster in which it is oxidized using heat before being sent to the leaching tanks as a slurry. The slurry is thickened and runs through a series of leaching tanks. The gold in the slurry adheres to carbon in the tanks. Stripping: The carbon is then moved into a stripping vessel where the gold is removed from the carbon by pumping a hot caustic solution through the carbon. The carbon is later recycled. Electro-winning: The gold-bearing solution is pumped through electro-winning cells or through a zinc precipitation circuit where the gold is recovered from the solution. Smelting: The gold is then melted in a furnace at about 1’064°C and poured into moulds, creating doré bars. Doré bars are unrefined gold bullion bars containing between 60% and 95% gold. WATER SUPPLY: For Misima Mine, process water is supplied from pit dewatering bores and in-pit water. Potable water is sourced from boreholes in the coastal limestone. For Porgera Mine, the main water supply of the mine is the Waile Creek Dam, located approximately 7 kilometres from the mine. The reservoir has a capacity of approximately 717, 000 m3 of water. Water for the grinding circuit is also extracted from Kogai Creek, which is located adjacent to the grinding circuit. The mine operates four water treatment plants for potable water and five sewage treatment plants. ENERGY SUPPLY: For Misima Mine, electricity is produced by the mine on site or with own power generators, from diesel and heavy fuel oil. For Porgera Mine, electricity is produced by the mine on site. Assumed with Mobius / Wohlwill electrolysis. Porgera's principal source of power is supplied by a 73-kilometre transmission line from the gas fired and PJV-owned Hides Power Station. The station has a total output of 62 megawatts (“MW”). A back up diesel power station is located at the mine and has an output of 13MW. The average power requirement of the mine is about 60 MW. For both Misima and Porgera Mines, an 18 MW diesel fired power station supplies electrical power. Diesel was used in the station due to the unavailability of previously supplied heavy fuel oil. technologyComment of gold-silver mine operation with refinery (CA-QC): One of the modelled mine is an open-pit mine and the two others are underground. technologyComment of gold-silver mine operation with refinery (RoW): The mining of ore from open pit mines is considered. technologyComment of platinum group metal, extraction and refinery operations (ZA): The ores from the different ore bodies are processed in concentrators where a PGM concentrate is produced with a tailing by product. The PGM base metal concentrate product from the different concentrators processing the different ores are blended during the smelting phase to balance the sulphur content in the final matte product. Smelter operators also carry out toll smelting from third part concentrators. The smelter product is send to the Base metal refinery where the PGMs are separated from the Base Metals. Precious metal refinery is carried out on PGM concentrate from the Base metal refinery to split the PGMs into individual metal products. Water analyses measurements for Anglo Platinum obtained from literature (Slatter et.al, 2009). Mudd, G., 2010. Platinum group metals: a unique case study in the sustainability of mineral resources, in: The 4th International Platinum Conference, Platinum in Transition “Boom or Bust.” Water share between MC and EC from Mudd (2010). Mudd, G., 2010. Platinum group metals: a unique case study in the sustainability of mineral resources, in: The 4th International Platinum Conference, Platinum in Transition “Boom or Bust.” technologyComment of primary zinc production from concentrate (RoW): The technological representativeness of this dataset is considered to be high as smelting methods for zinc are consistent in all regions. Refined zinc produced pyro-metallurgically represents less than 5% of global zinc production and less than 2% of this dataset. Electrometallurgical Smelting The main unit processes for electrometallurgical zinc smelting are roasting, leaching, purification, electrolysis, and melting. In both electrometallurgical and pyro-metallurgical zinc production routes, the first step is to remove the sulfur from the concentrate. Roasting or sintering achieves this. The concentrate is heated in a furnace with operating temperature above 900 °C (exothermic, autogenous process) to convert the zinc sulfide to calcine (zinc oxide). Simultaneously, sulfur reacts with oxygen to produce sulfur dioxide, which is subsequently converted to sulfuric acid in acid plants, usually located with zinc-smelting facilities. During the leaching process, the calcine is dissolved in dilute sulfuric acid solution (re-circulated back from the electrolysis cells) to produce aqueous zinc sulfate solution. The iron impurities dissolve as well and are precipitated out as jarosite or goethite in the presence of calcine and possibly ammonia. Jarosite and goethite are usually disposed of in tailing ponds. Adding zinc dust to the zinc sulfate solution facilitates purification. The purification of leachate leads to precipitation of cadmium, copper, and cobalt as metals. In electrolysis, the purified solution is electrolyzed between lead alloy anodes and aluminum cathodes. The high-purity zinc deposited on aluminum cathodes is stripped off, dried, melted, and cast into SHG zinc ingots (99.99 % zinc). Pyro-metallurgical Smelting The pyro-metallurgical smelting process is based on the reduction of zinc and lead oxides into metal with carbon in an imperial smelting furnace. The sinter, along with pre-heated coke, is charged from the top of the furnace and injected from below with pre-heated air. This ensures that temperature in the center of the furnace remains in the range of 1000-1500 °C. The coke is converted to carbon monoxide, and zinc and lead oxides are reduced to metallic zinc and lead. The liquid lead bullion is collected at the bottom of the furnace along with other metal impurities (copper, silver, and gold). Zinc in vapor form is collected from the top of the furnace along with other gases. Zinc vapor is then condensed into liquid zinc. The lead and cadmium impurities in zinc bullion are removed through a distillation process. The imperial smelting process is an energy-intensive process and produces zinc of lower purity than the electrometallurgical process. technologyComment of processing of anode slime from electrorefining of copper, anode (GLO): Based on typical current technology. Anode slime treatment by pressure leaching and top blown rotary converter. Production of Silver by Möbius Electrolysis, Gold by Wohlwill electrolysis, copper telluride cement and crude selenium to further processing. technologyComment of silver-gold mine operation with refinery (CL): OPEN PIT MINING: The ore is mined in four steps: drilling, blasting, loading and hauling. In the case of a surface mine, a pattern of holes is drilled in the pit and filled with explosives. The explosives are detonated in order to break up the ground so large shovels or front-end loaders can load it into haul trucks. BENEFICIATION: The processing plant consists of primary crushing, a pre-crushing circuit, (semi autogenous ball mill crushing) grinding, leaching, filtering and washing, Merrill-Crowe plant and doré refinery. The Merrill-Crowe metal recovery circuit is better than a carbon-in-pulp system for the high-grade silver material. Tailings are filtered to recover excess water as well as residual cyanide and metals. A dry tailings disposal system was preferred to a conventional wet tailings impoundment because of site-specific environmental considerations. technologyComment of silver-gold mine operation with refinery (RoW): Refinement is estimated with electrolysis-data. technologyComment of treatment of precious metal from electronics scrap, in anode slime, precious metal extraction (SE, RoW): Anode slime treatment by pressure leaching and top blown rotary converter. Production of Silver by Möbius Electrolysis, Gold by Wohlwill electrolysis, Palladium to further processing
technologyComment of gold mine operation and refining (SE): OPEN PIT MINING: The ore is mined in four steps: drilling, blasting, loading and hauling. In the case of a surface mine, a pattern of holes is drilled in the pit and filled with explosives. The explosives are detonated in order to break up the ground so large shovels or front-end loaders can load it into haul trucks. ORE AND WASTE HAULAGE: The haul trucks transport the ore to various areas for processing. The grade and type of ore determine the processing method used. Higher-grade ores are taken to a mill. Lower grade ores are taken to leach pads. Some ores may be stockpiled for later processing. HEAP LEACHING: The ore is crushed or placed directly on lined leach pads where a dilute cyanide solution is applied to the surface of the heap. The solution percolates down through the ore, where it leaches the gold and flows to a central collection location. The solution is recovered in this closed system. The pregnant leach solution is fed to electrowinning cells and undergoes the same steps as described below from Electro-winning. ORE PROCESSING: Milling: The ore is fed into a series of grinding mills where steel balls grind the ore to a fine slurry or powder. Oxidization and leaching: Some types of ore require further processing before gold is recovered. In this case, the slurry is pressure-oxidized in an autoclave before going to the leaching tanks or a dry powder is fed through a roaster in which it is oxidized using heat before being sent to the leaching tanks as a slurry. The slurry is thickened and runs through a series of leaching tanks. The gold in the slurry adheres to carbon in the tanks. Stripping: The carbon is then moved into a stripping vessel where the gold is removed from the carbon by pumping a hot caustic solution through the carbon. The carbon is later recycled. Electro-winning: The gold-bearing solution is pumped through electro-winning cells or through a zinc precipitation circuit where the gold is recovered from the solution. Smelting: The gold is then melted in a furnace at about 1’064°C and poured into moulds, creating doré bars. Doré bars are unrefined gold bullion bars containing between 60% and 95% gold. References: Newmont (2004) How gold is mined. Newmont. Retrieved from http://www.newmont.com/en/gold/howmined/index.asp technologyComment of gold-silver mine operation with refinery (PG): OPEN PIT MINING: The ore is mined in four steps: drilling, blasting, loading and hauling. In the case of a surface mine, a pattern of holes is drilled in the pit and filled with explosives. The explosives are detonated in order to break up the ground so large shovels or front-end loaders can load it into haul trucks. ORE AND WASTE HAULAGE: The haul trucks transport the ore to various areas for processing. The grade and type of ore determine the processing method used. Higher-grade ores are taken to a mill. Lower grade ores are taken to leach pads. Some ores may be stockpiled for later processing. HEAP LEACHING: The recovery processes of the Misima Mine are cyanide leach and carbon in pulp (CIP). The ore is crushed or placed directly on lined leach pads where a dilute cyanide solution is applied to the surface of the heap. The solution percolates down through the ore, where it leaches the gold and flows to a central collection location. The solution is recovered in this closed system. The pregnant leach solution is fed to electrowinning cells and undergoes the same steps as described below from Electro-winning. ORE PROCESSING: Milling: The ore is fed into a series of grinding mills where steel balls grind the ore to a fine slurry or powder. Oxidization and leaching: The recovery process in the Porgera Mine is pressure oxidation and cyanide leach. The slurry is pressure-oxidized in an autoclave before going to the leaching tanks or a dry powder is fed through a roaster in which it is oxidized using heat before being sent to the leaching tanks as a slurry. The slurry is thickened and runs through a series of leaching tanks. The gold in the slurry adheres to carbon in the tanks. Stripping: The carbon is then moved into a stripping vessel where the gold is removed from the carbon by pumping a hot caustic solution through the carbon. The carbon is later recycled. Electro-winning: The gold-bearing solution is pumped through electro-winning cells or through a zinc precipitation circuit where the gold is recovered from the solution. Smelting: The gold is then melted in a furnace at about 1’064°C and poured into moulds, creating doré bars. Doré bars are unrefined gold bullion bars containing between 60% and 95% gold. WATER SUPPLY: For Misima Mine, process water is supplied from pit dewatering bores and in-pit water. Potable water is sourced from boreholes in the coastal limestone. For Porgera Mine, the main water supply of the mine is the Waile Creek Dam, located approximately 7 kilometres from the mine. The reservoir has a capacity of approximately 717, 000 m3 of water. Water for the grinding circuit is also extracted from Kogai Creek, which is located adjacent to the grinding circuit. The mine operates four water treatment plants for potable water and five sewage treatment plants. ENERGY SUPPLY: For Misima Mine, electricity is produced by the mine on site or with own power generators, from diesel and heavy fuel oil. For Porgera Mine, electricity is produced by the mine on site. Assumed with Mobius / Wohlwill electrolysis. Porgera's principal source of power is supplied by a 73-kilometre transmission line from the gas fired and PJV-owned Hides Power Station. The station has a total output of 62 megawatts (“MW”). A back up diesel power station is located at the mine and has an output of 13MW. The average power requirement of the mine is about 60 MW. For both Misima and Porgera Mines, an 18 MW diesel fired power station supplies electrical power. Diesel was used in the station due to the unavailability of previously supplied heavy fuel oil. technologyComment of gold-silver mine operation with refinery (CA-QC): One of the modelled mine is an open-pit mine and the two others are underground. technologyComment of gold-silver mine operation with refinery (RoW): The mining of ore from open pit mines is considered. technologyComment of primary zinc production from concentrate (RoW): The technological representativeness of this dataset is considered to be high as smelting methods for zinc are consistent in all regions. Refined zinc produced pyro-metallurgically represents less than 5% of global zinc production and less than 2% of this dataset. Electrometallurgical Smelting The main unit processes for electrometallurgical zinc smelting are roasting, leaching, purification, electrolysis, and melting. In both electrometallurgical and pyro-metallurgical zinc production routes, the first step is to remove the sulfur from the concentrate. Roasting or sintering achieves this. The concentrate is heated in a furnace with operating temperature above 900 °C (exothermic, autogenous process) to convert the zinc sulfide to calcine (zinc oxide). Simultaneously, sulfur reacts with oxygen to produce sulfur dioxide, which is subsequently converted to sulfuric acid in acid plants, usually located with zinc-smelting facilities. During the leaching process, the calcine is dissolved in dilute sulfuric acid solution (re-circulated back from the electrolysis cells) to produce aqueous zinc sulfate solution. The iron impurities dissolve as well and are precipitated out as jarosite or goethite in the presence of calcine and possibly ammonia. Jarosite and goethite are usually disposed of in tailing ponds. Adding zinc dust to the zinc sulfate solution facilitates purification. The purification of leachate leads to precipitation of cadmium, copper, and cobalt as metals. In electrolysis, the purified solution is electrolyzed between lead alloy anodes and aluminum cathodes. The high-purity zinc deposited on aluminum cathodes is stripped off, dried, melted, and cast into SHG zinc ingots (99.99 % zinc). Pyro-metallurgical Smelting The pyro-metallurgical smelting process is based on the reduction of zinc and lead oxides into metal with carbon in an imperial smelting furnace. The sinter, along with pre-heated coke, is charged from the top of the furnace and injected from below with pre-heated air. This ensures that temperature in the center of the furnace remains in the range of 1000-1500 °C. The coke is converted to carbon monoxide, and zinc and lead oxides are reduced to metallic zinc and lead. The liquid lead bullion is collected at the bottom of the furnace along with other metal impurities (copper, silver, and gold). Zinc in vapor form is collected from the top of the furnace along with other gases. Zinc vapor is then condensed into liquid zinc. The lead and cadmium impurities in zinc bullion are removed through a distillation process. The imperial smelting process is an energy-intensive process and produces zinc of lower purity than the electrometallurgical process. technologyComment of processing of anode slime from electrorefining of copper, anode (GLO): Based on typical current technology. Anode slime treatment by pressure leaching and top blown rotary converter. Production of Silver by Möbius Electrolysis, Gold by Wohlwill electrolysis, copper telluride cement and crude selenium to further processing. technologyComment of silver-gold mine operation with refinery (CL): OPEN PIT MINING: The ore is mined in four steps: drilling, blasting, loading and hauling. In the case of a surface mine, a pattern of holes is drilled in the pit and filled with explosives. The explosives are detonated in order to break up the ground so large shovels or front-end loaders can load it into haul trucks. BENEFICIATION: The processing plant consists of primary crushing, a pre-crushing circuit, (semi autogenous ball mill crushing) grinding, leaching, filtering and washing, Merrill-Crowe plant and doré refinery. The Merrill-Crowe metal recovery circuit is better than a carbon-in-pulp system for the high-grade silver material. Tailings are filtered to recover excess water as well as residual cyanide and metals. A dry tailings disposal system was preferred to a conventional wet tailings impoundment because of site-specific environmental considerations. technologyComment of silver-gold mine operation with refinery (RoW): Refinement is estimated with electrolysis-data. technologyComment of treatment of crust from Parkes process for lead production (GLO): Processing of Parkes desilvering crust by hot pressing, dezincing (vacuum distillation), cupellation of lead and moebius electrolysis (electrowinning) technologyComment of treatment of precious metal from electronics scrap, in anode slime, precious metal extraction (SE, RoW): Anode slime treatment by pressure leaching and top blown rotary converter. Production of Silver by Möbius Electrolysis, Gold by Wohlwill electrolysis, Palladium to further processing technologyComment of treatment of waste x-ray film (GLO): None
technologyComment of barite production (CA-QC, RER, RoW): Barite is mined both in open pit and underground mines. About 60 to 120 kg of Barite can be yielded from one cubic meter of ore. The ore is transported via lorry (usually less than 5km) to a washing installation. Subsequently, it is separated from the water and grinded wet or dry. Between 65% and 85% of barite contained in the ore can be extracted. This dataset includes resource extraction and processing of the material. technologyComment of niobium mine operation and beneficiation, from pyrochlore ore (BR, RoW): Open-pit mining is applied and hydraulic excavators are used to extract the ore with different grades, which is transported to stockpiles awaiting homogenization through earth-moving equipment in order to attain the same concentration. Conveyor belts (3.5 km) are utilized to transport the homogenized ore to the concentration unit. Initially, the ore passes through a jaw crusher and moves to the ball mills, where the pyrochlore grains (1 mm average diameter) are reduced to diameters less than 0.104 mm. In the ball mills, recycled water is added in order to i) granulate the concentrate and ii) remove the gas from the sintering unit. The granulated ore undergoes i) magnetic separation, where magnetite is removed and is sold as a coproduct and ii) desliming in order to remove fractions smaller than 5μm by utilizing cyclones. Then the ore enters the flotation process - last stage of the beneficiation process – where the pyrochlore particles come into contact with flotation chemicals (hydrochloric & fluorosilic acid, triethylamene and lime), thereby removing the solid fractions and producing pyrochlore concentrate and barite as a coproduct which is also sold. The produced concentrate contains 55% Nb2O5 and 11% water and moves to the sintering unit, via tubes or is transported in bags while the separated and unused minerals enter the tailings dam. In the sintering unit, the pyrochlore concentrate undergoes pelletizing, sintering, crushing and classification. These units not only accumulate the material but are also responsible for removing sulfur and water from the concentrate. Then the concentrate enters the dephosphorization unit, where phosphorus and lead are removed from the concentrate. The removal of sulphur and phosphorus have to be executed because of the local pyrochlore ore composition. Then the concentrate undergoes a carbothermic reduction by using charcoal and petroleum coke, producing a refined concentrate, 63% Nb2O5 and tailings with high lead content that are disposed in the tailings dam again.
technologyComment of bulk lead-zinc concentrate to generic markets for zinc concentrate and lead concentrate (GLO): No comment present technologyComment of gold-silver mine operation and beneficiation (CA-QC): The ore is mined in an underground mine and transported by trucks to the mill for further processing. The ore is then fed into a series of grinding mills where steel balls grind the ore. Then follows the steps of flotation of copper and zinc, concentrate handling, cyanide destruction and backfilling of the tailings, refining of gold by electro-winning and melting in furnace to produce the gold and silver ingots. 20% of the tailings produce are sent underground to be used as backfill; sulfidic tailing is managed on site in tailings ponds. technologyComment of metalliferous hydroxide sludge to market for zinc concentrate (GLO): No comment present technologyComment of silver mine operation with extraction (PE): The exploitation methods include overhand cut and fill and bench and fill, both mechanized. The ore is transported by rail using locomotives and mining cars to the loading areas and to the concentration plant. The barren material is recirculated as backfill to the pits, and the excess material is transported to the barren material deposit located on the surface. The metallurgical process consists in two circuits: Circuit 1 consists of primary crushing, milling, and ore flotation, obtaining lead-silver, zinc-silver, and pyrite concentrates; while Circuit 2 consists of primary crushing, milling, and ore flotation, obtaining lead-silver, zinc-silver, and pyrite concentrates. The pyrite concentrates from both circuits are sent to the cyanidation plant. The solution obtained is treated using the Merrill-Crowe process, and the precipitate obtained is dried and smelted to finally obtain high-purity silver bars. technologyComment of zinc mine operation (GLO): The technological representativeness of this dataset is considered to be high as mining and concentration methods for zinc are consistent in all regions. Mining The mining of zinc ore includes underground and open cast mining processes. Within the global zinc industry, about 80% of zinc ore comes from underground mines and 20% from open pit or combination mines. - Underground Mining: Access is via vertical shafts or inclined roadways. There are usually two access routes (one for mining personnel and materials, and one for the ore) for safety and for ease of ventilation (fresh air comes in one and is then exhausted out of the other). These are permanent structures and therefore require strong roof supports (often including "bolts" into the rock to tie the layers together for strength). Once at the correct depth has been reached, horizontal tunnels are driven to reach the ore deposit. These are often temporary, so the support requirements are less substantial. Transport for personnel and materials can be by train, truck or conveyor belts. The largest share of the consumed fuels is diesel followed by electricity. Other major inputs include explosives and water. - Open Pit Mining: Hard-rock surface mining usually includes drilling, blasting, or a combination of both processes, and then lifting of the broken ore either into trucks or onto conveyors for transportation to the processing plant. This lifting is usually by excavator (electric or hydraulic; with shovel or backhoe configuration) or front-end loader. Benefication (Comminution and Flotation) Zinc ore is milled and mixed with water to recover a fine concentrate by gravity and elutriation techniques, creating a slurry. The separation process of the metal from the slurry is realized through the addition of various floatation chemicals.
This production mix is fully based on the related exploitation of copper ore. technologyComment of copper mine operation and beneficiation, sulfide ore (CA, CL, CN, RU, US, RoW): Based on typical current technology. Mining is done 70% open pit and 30% underground, followed by joint beneficiation of copper and molybdenite trough flotation, where considerable amounts of agents are added. Overburden is disposed separate to sulfidic tailings near the mining site. No dewatering (or other pre-treatment) of the tailings of is assumed as this is considered a treatment activity that occurs only at selective sites and is therefore modelled separately. technologyComment of molybdenite mine operation (GLO): imageUrlTagReplacead2d66f4-3a0d-4ae6-a5ca-e63fd821a4fc Mining. Sulphidic copper ores are mined only 30% underground, the major part is mined in large open cut operations. The ore mined in 1900 in the U.S. had a high content of 3.4% and was mined entirely underground. Open pit mining permits the use of very large equipment. Resulting economies of scale enable the exploitation of lower grade disseminated (porphyry) ores – the ores now mainly mined. The major emissions are due to mineral born pollutants in the effluents. Open cut mining generates large quantities of dust, which contains elevated contents of metals and sulphur. Rain percolates through overburden and accounts to metal emissions to groundwater. Overburden is deposed close to the mine. No overburden is refilled. imageUrlTagReplace47e24476-56f3-4016-9151-88908e3e0072 Beneficiation. After mining, the ore is first ground. In a next step it is subjected to gravity concentration to separate the metal-bearing particles from the unwanted minerals. After this first concentration step, flotation is carried out to remove the gangue from the sulphidic minerals. For neutralisation lime is added. In the flotation several organic chemicals ( such as collectors (xanthate or aerofloat) and frothing reagent (eg. Methyl Isobutyl Carbinol)) are used as collector, frother, activator, depressor and flocculant. Sometimes cyanide is used as depressant for pyrite. Tailings usually are led to tailings heaps or ponds. As a result, copper concentrates containing around 30% Cu are produced. Molybdenite concentrate are further ground and purified. It leaves the process as co-product with a concentration of 90 – 95 % Molybdenum disulphide. The concentrated ore is fed to the metallurgy, which is assumed to be on-site. Ore handling and processing produce large amounts of dust, containing PM10 and several metals from the ore itself. Flotation produces effluents containing several organic agents used. Some of these chemicals evaporate and account for VOC emissions to air. Namely xanthates decompose hydrolytically to release carbon disulphide. Tailings effluent contains additional sulphuric acid from acid rock drainage. Tailings are deposed as piles and in ponds. In the sulphidic tailings occurs acid rock drainage (ARD) over a long period of time. Reserves and resources: Molybdenum and Copper are coexisting in porphyry deposits of the copper-molybdenum type, as molybdenite (MoS2) and chalcopyrite (CuFeS2). About half of the world-wide produced molybdenum is a co-product of the primary copper industry while for another substantial part copper is the co-product. Hence almost all of the molybdenum is produced in a process similar to the copper primary production. Molybdenum secondary production – mainly from spent petroleum catalysts – is not remarkable, and no secondary production is considered in this study. It's estimated that 30% of the molybdenum is re-used in the form of the molybdenum content steel alloys which are recycled to the foundries. Secondary production of copper from scrap plays an important role. The resources of primary copper are limited, a continuous depletion within 60 years is estimated. Land-based resources of copper are estimated to be 1.6 billion tons , and resources in deep-sea nodules are estimated to be 700 million tons. A detailed overview over the global refinery production and a statistic on US use and production of copper is available in the online version of the USGS “Mineral Commodity Summary”. The world-wide mine estimated reserves by country are listed in Tab. 1. Exploitable reserves of recoverable copper were estimated at about 100 million tons in 1935; new discoveries raised this to 212 million tons in 1960. Reserves grew again sharply to 340 million metric tons (MMT) in 1984, but since then they have declined slowly to 321 MMT in 1990 and 310 MMT in 1994. Estimates vary according to prices and assumptions. Total potential resources have increased somewhat over the same period, from 500 MMT to around 590 MMT. As a matter of interest, cumulative global production of copper between 1970 and 1996 was 216 MMT. With the actual mine production of around 13.5 MMT/a, the reserves would last 36 years and the reserve base 70 years. Reserves of molybdenite in the market economy countries have been estimated in a survey evaluating identified ore bodies, i.e., those which have been explored as well as those which have been exploited. The results indicate the following amounts of recoverable molybdenum: United States, 4100 kt; Chile, 1770 kt; Canada, 928 kt; Mexico, 306 kt; Peru, 288 kt; other countries, 356 kt. Ore bodies producing primarily molybdenum contain 55 % of the reserves identified; only 29 % of these ore bodies were being exploited at the time of the survey (January 1985). Operations producing molybdenum as a byproduct contained the remaining 45 % of reserves and 67 % of them were producing molybdenite. The estimated total recoverable molybdenum from primary and byproduct reserves is listed in Tab. 2. References: Krauss et al. (1999), Sebenik et al. (1997), USGS (2003), Ayres et al. (2002).
technologyComment of chromite ore concentrate production (RoW): Mining is done 21% open pit and 79% underground, followed by a benefication of the ore trough classification. Overburden and tailings are disposed near the mining site. MINING: Chromite ores are usually mined underground. An estimated share of 71% underground mining has been reported for activities in the mine production in 1994. This represents 78% of the total production. Of a surveyed part of 52% of the total world production, 69% of the chromite originated from stratiform deposits. Emissions and waste: The major emissions are due to mineral born pollutants in the effluents. Open cut mining generates large quantities of dust, which contains elevated contents of metals. Rain percolates through overburden and leads to metal emissions to groundwater. Overburden is deposed close to the mine. BENEFICIATION: After mining, the ore is first crushed in several stages with jaw and / or cone crushers, and then subsequently ground with rod and or ball mills and finally screened for classification. In a second step the classified material is subjected to gravity concentration to separate the metal-bearing particles from the unwanted minerals. For this drum separators and de-watering screens for lumps are used and cone separators and a high-gradient magnetic separator for fine material. No flotation is done. The separated gangue is disposed in tailings ponds, the concentrated ore is fed to the metallurgy, which is on-site. Chromite yields vary in a range from 65% to 85%. There's no treatment of wastewater. Emissions and waste: Ore handling and processing produce large amounts of dust, containing PM10 and several metals from the ore itself. Tailings are deposed as piles and in ponds. Since the tailings are not sulphidic, no acid rock drainage (ARD) occurs. In the tailings material the most significant contents are Cr and Ni, which occur as insoluble compounds and are considered not to cause any negative effects. References: Adelhardt W. and Antrekowitsch H. (1998) Stoffmengenflüsse und Energie-bedarf bei der Gewinnung ausgewählter mineralischer Rohstoffe; Teilstudie Chrom. In: Geologisches Jahrbuch, Vol. Sonderhefte SH 3. Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover. ISBN 3-510-95831-4. IPPC (2002) Integrated Pollution Prevention and Control (IPPC); Draft Refer-ence Document on Best Available Techniques for Management of Tailings and Waste-Rock in Mining Activities. European Commission. Retrieved at 01.03.2003 from http://www.jrc.es/pub/english.cgi/0/733169 technologyComment of chromite ore concentrate production (KZ): Mining is done both open pit and underground, followed by a benefication of the ore trough classification. Overburden and tailings are disposed near the mining site. MINING: Chromite ores are usually mined underground. An estimated share of 93% underground mining has been reported for activities in the mine production in Donskoy mine operation site (leader in chromite ore production in Kazakhstan), while the remaining 7% is open pit (Kaplunov et al. 2018). Emissions and waste: The major emissions are due to mineral born pollutants in the effluents. Open cut mining generates large quantities of dust, which contains elevated contents of metals. Rain percolates through overburden and leads to metal emissions to groundwater. Overburden is deposed close to the mine. BENEFICIATION: After mining, the ore is first crushed in several stages with jaw and / or cone crushers, and then subsequently ground with rod and or ball mills and finally screened for classification. In a second step the classified material is subjected to gravity concentration to separate the metal-bearing particles from the unwanted minerals. For this drum separators and de-watering screens for lumps are used and cone separators and a high-gradient magnetic separator for fine material. No flotation is done. The separated gangue is disposed in tailings ponds, the concentrated ore is fed to the metallurgy, which is on-site. Chromite yields vary in a range from 65% to 85%. There's no treatment of wastewater. Emissions and waste: Ore handling and processing produce large amounts of dust, containing PM10 and several metals from the ore itself. Tailings are deposed as piles and in ponds. Since the tailings are not sulphidic, no acid rock drainage (ARD) occurs. In the tailings material the most significant contents are Cr and Ni, which occur as insoluble compounds and are considered not to cause any negative effects. References: Adelhardt W. and Antrekowitsch H. (1998) Stoffmengenflüsse und Energie-bedarf bei der Gewinnung ausgewählter mineralischer Rohstoffe; Teilstudie Chrom. In: Geologisches Jahrbuch, Vol. Sonderhefte SH 3. Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover. ISBN 3-510-95831-4. IPPC (2002) Integrated Pollution Prevention and Control (IPPC); Draft Refer-ence Document on Best Available Techniques for Management of Tailings and Waste-Rock in Mining Activities. European Commission. Retrieved at 01.03.2003 from http://www.jrc.es/pub/english.cgi/0/733169 Kaplunov, D., Bekbergenov, D., & Djangulova, G. (2018). Particularities of solving the problem of sustainable development of chromite underground mining at deep horizons by means of combined geotechnology. In E3S Web of Conferences (Vol. 56, p. 01015). EDP Sciences.
technologyComment of manganese concentrate production (GLO): Mining is done 70% open pit and 30% underground, followed by a beneficiation of the ore trough classification. Overburden and tailings are non-sulphidic , they are disposed near the mining site. MINING: Manganese ores are usually mined in open pits. It's been estimated a share of 70% surface mining activities in the mine production in 1994. The deposits are of various nature and therefore the average manganese concentration differs greatly, from Asia with 24%wt to Australia with 48.5%wt and a world-wide average of 35.7%wt manganese content in the ore. Emissions and waste: The major emissions are due to mineral born pollutants in the effluents. Open cut mining generates large quantities of dust, which contains elevated contents of metals. Rain percolate through overburden and accounts to metal emissions to groundwater. Overburden is deposed close to the mine. BENEFICIATION: After mining, the ore is first crushed in several stages with jaw and / or cone crushers, and then subsequently ground with rod and or ball mills and finally screened for classification. In a second step the classified material it is subjected to gravity concentration to separate the metal-bearing particles from the unwanted minerals. For this drum separators and de-watering screens for lumps are used and cone separators and a high-gradient magnetic separator for fine material. No flotation is done. Recovery of Manganese vary in a range from 65% to 75%. Emissions and waste: Ore handling and processing produce large amounts of dust, containing PM10 and several metals from the ore itself. Tailings are deposed as piles and in ponds. Since the tailings are not sulphidic, no acid rock drainage (ARD) occurs. References: Adelhardt W. and Saiger H. (1999) Stoffmengenflüsse und Energiebedarf bei der Gewinnung ausgewählter mineralischer Rohstoffe; Teilstudie Mangan. In: Geo-logisches Jahrbuch, Vol. Sonderhefte SH 8. Bundesanstalt für Geowissen-schaften und Rohstoffe, Hannover. ISBN 3-510-95830-6.
technologyComment of heavy mineral sand quarry operation (AU, RoW): There are two ways for mining zircon sand: dry & wet mining with the choice of mining depending on the structure of the geological deposit. During wet mining, floating dredges and a floating concentrator are utilized in an enclosed pond, where the concentrator moves behind the dredges. Wet mining is the preferred technique for large continuous deposits with amounts of clay. For all other types of HMS deposits (hard-ground deposits, discontinuous deposits and small tonnage high-grade deposits), dry mining is the most preferred mining process. Dry mining utilizes earth-moving machinery (loaders, excavators, scrapes) for the purposes of sand excavation and transportation to the concentrator. The mining unit plants used in dry mining are mobile in order to minimize the transport distance of the sand. After the transportation of the HMS to the respective concentrator, wet gravity separations techniques (spirals) are usually applied for the production of the heavy mineral concentrate (HMC), although some hard-rock sites use bulk froth flotation to extract the heavy minerals from the sand. The produced slurry from dry and wet mining is then fed to the concentrator, where the HMC (90-96% heavy minerals) is produced along with the tailings that are backfilled in the mined areas. The HMC is transported to a mineral separation plant (MSP), where the HMC is subjected to scrubbing, drying and is separated by magnetic, electrostatic and gravity separation, producing zircon sand, ilmenite and rutile, with the last two considered as byproducts. technologyComment of ilmenite - magnetite mine operation (GLO): No comment present
technologyComment of mercury production (GLO): Data approximated with data from lime mining, crushing and milling plus estimation of the additional furnace operation step, based on information in literature and own assumptions. technologyComment of treatment of used fluorescent lamp (GLO): Dry dismantling technology of fluorescent lamps – with cutting, blowing, crushing and air exhaust cleaning steps.
technologyComment of cobalt production (GLO): Cobalt, as a co-product of nickel and copper production, is obtained using a wide range of technologies. The initial life cycle stage covers the mining of the ore through underground or open cast methods. The ore is further processed in beneficiation to produce a concentrate and/or raffinate solution. Metal selection and further concentration is initiated in primary extraction, which may involve calcining, smelting, high pressure leaching, and other processes. The final product is obtained through further refining, which may involve processes such as re-leaching, selective solvent / solution extraction, selective precipitation, electrowinning, and other treatments. Transport is reported separately and consists of only the internal movements of materials / intermediates, and not the movement of final product. Due to its intrinsic value, cobalt has a high recycling rate. However, much of this recycling takes place downstream through the recycling of alloy scrap into new alloy, or goes into the cobalt chemical sector as an intermediate requiring additional refinement. Secondary production, ie production from the recycling of cobalt-containing wastes, is considered in this study in so far as it occurs as part of the participating companies’ production. This was shown to be of very limited significance (less than 1% of cobalt inputs). The secondary materials used for producing cobalt are modelled as entering the system free of environmental burden. technologyComment of copper mine operation and beneficiation, sulfide ore (AU, CA, CL, CN, ID, KZ, RU, US, ZM, RoW): Based on typical current technology. Mining is done 70% open pit and 30% underground, followed by joint beneficiation of copper and molybdenite trough flotation, where considerable amounts of agents are added. Overburden is disposed separate to sulfidic tailings near the mining site. No dewatering (or other pre-treatment) of the tailings of is assumed as this is considered a treatment activity that occurs only at selective sites and is therefore modelled separately. technologyComment of gold-silver mine operation and beneficiation (CA-QC): The ore is mined in an underground mine and transported by trucks to the mill for further processing. The ore is then fed into a series of grinding mills where steel balls grind the ore. Then follows the steps of flotation of copper and zinc, concentrate handling, cyanide destruction and backfilling of the tailings, refining of gold by electro-winning and melting in furnace to produce the gold and silver ingots. 20% of the tailings produce are sent underground to be used as backfill; sulfidic tailing is managed on site in tailings ponds. technologyComment of molybdenite mine operation (GLO): imageUrlTagReplacead2d66f4-3a0d-4ae6-a5ca-e63fd821a4fc Mining. Sulphidic copper ores are mined only 30% underground, the major part is mined in large open cut operations. The ore mined in 1900 in the U.S. had a high content of 3.4% and was mined entirely underground. Open pit mining permits the use of very large equipment. Resulting economies of scale enable the exploitation of lower grade disseminated (porphyry) ores – the ores now mainly mined. The major emissions are due to mineral born pollutants in the effluents. Open cut mining generates large quantities of dust, which contains elevated contents of metals and sulphur. Rain percolates through overburden and accounts to metal emissions to groundwater. Overburden is deposed close to the mine. No overburden is refilled. imageUrlTagReplace47e24476-56f3-4016-9151-88908e3e0072 Beneficiation. After mining, the ore is first ground. In a next step it is subjected to gravity concentration to separate the metal-bearing particles from the unwanted minerals. After this first concentration step, flotation is carried out to remove the gangue from the sulphidic minerals. For neutralisation lime is added. In the flotation several organic chemicals ( such as collectors (xanthate or aerofloat) and frothing reagent (eg. Methyl Isobutyl Carbinol)) are used as collector, frother, activator, depressor and flocculant. Sometimes cyanide is used as depressant for pyrite. Tailings usually are led to tailings heaps or ponds. As a result, copper concentrates containing around 30% Cu are produced. Molybdenite concentrate are further ground and purified. It leaves the process as co-product with a concentration of 90 – 95 % Molybdenum disulphide. The concentrated ore is fed to the metallurgy, which is assumed to be on-site. Ore handling and processing produce large amounts of dust, containing PM10 and several metals from the ore itself. Flotation produces effluents containing several organic agents used. Some of these chemicals evaporate and account for VOC emissions to air. Namely xanthates decompose hydrolytically to release carbon disulphide. Tailings effluent contains additional sulphuric acid from acid rock drainage. Tailings are deposed as piles and in ponds. In the sulphidic tailings occurs acid rock drainage (ARD) over a long period of time. Reserves and resources: Molybdenum and Copper are coexisting in porphyry deposits of the copper-molybdenum type, as molybdenite (MoS2) and chalcopyrite (CuFeS2). About half of the world-wide produced molybdenum is a co-product of the primary copper industry while for another substantial part copper is the co-product. Hence almost all of the molybdenum is produced in a process similar to the copper primary production. Molybdenum secondary production – mainly from spent petroleum catalysts – is not remarkable, and no secondary production is considered in this study. It's estimated that 30% of the molybdenum is re-used in the form of the molybdenum content steel alloys which are recycled to the foundries. Secondary production of copper from scrap plays an important role. The resources of primary copper are limited, a continuous depletion within 60 years is estimated. Land-based resources of copper are estimated to be 1.6 billion tons , and resources in deep-sea nodules are estimated to be 700 million tons. A detailed overview over the global refinery production and a statistic on US use and production of copper is available in the online version of the USGS “Mineral Commodity Summary”. The world-wide mine estimated reserves by country are listed in Tab. 1. Exploitable reserves of recoverable copper were estimated at about 100 million tons in 1935; new discoveries raised this to 212 million tons in 1960. Reserves grew again sharply to 340 million metric tons (MMT) in 1984, but since then they have declined slowly to 321 MMT in 1990 and 310 MMT in 1994. Estimates vary according to prices and assumptions. Total potential resources have increased somewhat over the same period, from 500 MMT to around 590 MMT. As a matter of interest, cumulative global production of copper between 1970 and 1996 was 216 MMT. With the actual mine production of around 13.5 MMT/a, the reserves would last 36 years and the reserve base 70 years. Reserves of molybdenite in the market economy countries have been estimated in a survey evaluating identified ore bodies, i.e., those which have been explored as well as those which have been exploited. The results indicate the following amounts of recoverable molybdenum: United States, 4100 kt; Chile, 1770 kt; Canada, 928 kt; Mexico, 306 kt; Peru, 288 kt; other countries, 356 kt. Ore bodies producing primarily molybdenum contain 55 % of the reserves identified; only 29 % of these ore bodies were being exploited at the time of the survey (January 1985). Operations producing molybdenum as a byproduct contained the remaining 45 % of reserves and 67 % of them were producing molybdenite. The estimated total recoverable molybdenum from primary and byproduct reserves is listed in Tab. 2. References: Krauss et al. (1999), Sebenik et al. (1997), USGS (2003), Ayres et al. (2002). technologyComment of primary zinc production from concentrate (RoW): The technological representativeness of this dataset is considered to be high as smelting methods for zinc are consistent in all regions. Refined zinc produced pyro-metallurgically represents less than 5% of global zinc production and less than 2% of this dataset. Electrometallurgical Smelting The main unit processes for electrometallurgical zinc smelting are roasting, leaching, purification, electrolysis, and melting. In both electrometallurgical and pyro-metallurgical zinc production routes, the first step is to remove the sulfur from the concentrate. Roasting or sintering achieves this. The concentrate is heated in a furnace with operating temperature above 900 °C (exothermic, autogenous process) to convert the zinc sulfide to calcine (zinc oxide). Simultaneously, sulfur reacts with oxygen to produce sulfur dioxide, which is subsequently converted to sulfuric acid in acid plants, usually located with zinc-smelting facilities. During the leaching process, the calcine is dissolved in dilute sulfuric acid solution (re-circulated back from the electrolysis cells) to produce aqueous zinc sulfate solution. The iron impurities dissolve as well and are precipitated out as jarosite or goethite in the presence of calcine and possibly ammonia. Jarosite and goethite are usually disposed of in tailing ponds. Adding zinc dust to the zinc sulfate solution facilitates purification. The purification of leachate leads to precipitation of cadmium, copper, and cobalt as metals. In electrolysis, the purified solution is electrolyzed between lead alloy anodes and aluminum cathodes. The high-purity zinc deposited on aluminum cathodes is stripped off, dried, melted, and cast into SHG zinc ingots (99.99 % zinc). Pyro-metallurgical Smelting The pyro-metallurgical smelting process is based on the reduction of zinc and lead oxides into metal with carbon in an imperial smelting furnace. The sinter, along with pre-heated coke, is charged from the top of the furnace and injected from below with pre-heated air. This ensures that temperature in the center of the furnace remains in the range of 1000-1500 °C. The coke is converted to carbon monoxide, and zinc and lead oxides are reduced to metallic zinc and lead. The liquid lead bullion is collected at the bottom of the furnace along with other metal impurities (copper, silver, and gold). Zinc in vapor form is collected from the top of the furnace along with other gases. Zinc vapor is then condensed into liquid zinc. The lead and cadmium impurities in zinc bullion are removed through a distillation process. The imperial smelting process is an energy-intensive process and produces zinc of lower purity than the electrometallurgical process. technologyComment of smelting and refining of nickel concentrate, 16% Ni (GLO): Extrapolated from a typical technology for smelting and refining of nickel ore. MINING: 95% of sulphidic nickel ores are mined underground in depths between 200m and 1800m, the ore is transferred to the beneficiation. Widening of the tunnels is mainly done by blasting. The overburden – material, which does not contain PGM-bearing ore – is deposed off-site and is partially refilled into the tunnels. Emissions: The major emissions are due to mineral born pollutants in the effluents. The underground mining operations generate roughly 80 % of the dust emissions from open pit operations, since the major dust sources do not take place underground. Rain percolate through overburden and accounts to metal emissions to groundwater. Waste: Overburden is deposed close to the mine. Acid rock drainage occurs over a long period of time. BENEFICIATION: After mining, the ore is first ground. In a next step it is subjected to gravity concentration to separate the metallic particles from the PGM-bearing minerals. After this first concentration step, flotation is carried out to remove the gangue from the sulphidic minerals. For neutralisation lime is added. In the flotation several organic chemicals are used as collector, frother, activator, depressor and flocculant. Sometimes cyanide is used as depressant for pyrite. Tailings usually are led to tailing heaps or ponds. As a result, nickel concentrates containing 7 - 25% Ni are produced. Emissions: Ore handling and processing produce large amounts of dust, containing PM10 and several metals from the ore itself. Flotation produce effluents containing several organic agents used. Some of these chemicals evaporate and account for VOC emissions to air. Namely xanthates decompose hydrolytically to release carbon disulphide. Tailings effluent contains additional sulphuric acid from acid rock drainage. Waste: Tailings are deposed as piles and in ponds. Acid rock drainage occurs over a long period of time. METALLURGY AND REFINING: There are many different process possibilities to win the metal. The chosen process depends on the composition of the ore, the local costs of energy carrier and the local legislation. Basically two different types can be distinguished: the hydrometallurgical and the pyrometallurgical process, which paired up with the refining processes, make up five major production routes (See Tab.1). All this routes are covered, aggregated according to their market share in 1994. imageUrlTagReplace00ebef53-ae97-400f-a602-7405e896cb76 Pyrometallurgy. The pyrometallurgical treatment of nickel concentrates includes three types of unit operation: roasting, smelting, and converting. In the roasting step sulphur is driven off as sulphur dioxide and part of the iron is oxidised. In smelting, the roaster product is melted with a siliceous flux which combines with the oxidised iron to produce two immiscible phases, a liquid silicate slag which can be discarded, and a solution of molten sulphides which contains the metal values. In the converting operation on the sulphide melt, more sulphur is driven off as sulphur dioxide, and the remaining iron is oxidised and fluxed for removal as silicate slag, leaving a high-grade nickel – copper sulphide matte. In several modern operations the roasting step has been eliminated, and the nickel sulphide concentrate is treated directly in the smelter. Hydrometallurgy: Several hydrometallurgical processes are in commercial operation for the treatment of nickel – copper mattes to produce separate nickel and copper products. In addition, the hydrometal-lurgical process developed by Sherritt Gordon in the early 1950s for the direct treatment of nickel sulphide concentrates, as an alternative to smelting, is still commercially viable and competitive, despite very significant improvements in the economics and energy efficiency of nickel smelting technology. In a typical hydrometallurgical process, the concentrate or matte is first leached in a sulphate or chloride solution to dissolve nickel, cobalt, and some of the copper, while the sulphide is oxidised to insoluble elemental sulphur or soluble sulphate. Frequently, leaching is carried out in a two-stage countercurrent system so that the matte can be used to partially purify the solution, for example, by precipitating copper by cementation. In this way a nickel – copper matte can be treated in a two-stage leach process to produce a copper-free nickel sulphate or nickel chloride solution, and a leach residue enriched in copper. Refining: In many applications, high-purity nickel is essential and Class I nickel products, which include electrolytic cathode, carbonyl powder, and hydrogen-reduced powder, are made by a variety of refining processes. The carbonyl refining process uses the property of nickel to form volatile nickel-carbonyl compounds from which elemental nickel subsides to form granules. Electrolytic nickel refineries treat cast raw nickel anodes in a electrolyte. Under current the anode dissolves and pure nickel deposits on the cathode. This electrorefining process is obsolete because of high energy demand and the necessity of building the crude nickel anode by reduction with coke. It is still practised in Russia. Most refineries recover electrolytic nickel by direct electrowinning from purified solutions produced by the leaching of nickel or nickel – copper mattes. Some companies recover refined nickel powder from purified ammoniacal solution by reduction with hydrogen. Emissions: In all of the metallurgical steps, sulphur dioxide is emitted to air. Recovery of sulphur dioxide is only economic for high concentrated off-gas. Given that In the beneficiation step, considerable amounts of lime are added to the ore for pH-stabilisation, lime forms later flux in the metallurgical step, and decomposes into CO2 to form calcite. Dust carry over from the roasting, smelting and converting processes. Particulate emissions to the air consist of metals and thus are often returned to the leaching process after treatment. Chlorine is used in some leaching stages and is produced during the subsequent electrolysis of chloride solution. The chlorine evolved is collected and re-used in the leach stage. The presence of chlorine in wastewater can lead to the formation of organic chlorine compounds (AOX) if solvents etc. are also present in a mixed wastewater. VOCs can be emitted from the solvent extraction stages. A variety of solvents are used an they contain various complexing agents to form complexes with the desired metal that are soluble in the organic layer. Metals and their compounds and substances in suspension are the main pollutants emitted to water. The metals concerned are Cu, Ni, Co, As and Cr. Other significant substances are chlorides and sulphates. Wastewater from wet gas cleaning (if used) of the different metallurgical stages are the most important sources. The leaching stages are usually operated on a closed circuit and drainage systems, and are therefore regarded as minor sources. In the refining step, the combustion of sulphur leads to emissions of SO2. Nitrogen oxides are produced in significant amounts during acid digestion using nitric acid. Chlorine and HCl can be formed during a number of digestion, electrolytic and purification processes. Chlorine is used extensively in the Miller process and in the dissolution stages using hydrochloric acid and chlorine mixtrues respectively. Dust and metals are generally emitted from incinerators and furnaces. VOC can be emitted from solvent extraction processes, while organic compounds, namely dioxins, can be emitted from smelting stages resulting from the poor combustion of oil and plastic in the feed material. All these emissions are subject to abatement technologies and controlling. Large quantities of effluents contain amounts of metals and organic substances. Waste: Regarding the metallurgical step, several co-products, residues and wastes, which are listed in the European Waste Catalogue, are generated. Some of the process specific residues can be reused or recovered in preliminary process steps (e. g. dross, filter dust) or construction (e. g. cleaned slag). Residues also arise from the treatment of liquid effluents, the main residue being gypsum waste and metal hydroxides from the wastewater neutralisation plant. These residuals have to be disposed, usually in lined ponds. In the refining step, quantities of solid residuals are also generated, which are mostly recycled within the process or sent to other specialists to recover any precious metals. Final residues generally comprise hydroxide filter cakes (ironhydroxide, 60% water, cat I industrial waste). References: Kerfoot D. G. E. (1997) Nickel. In: Ullmann's encyclopedia of industrial chemis-try (ed. Anonymous). 5th edition on CD-ROM Edition. Wiley & Sons, London. technologyComment of zinc mine operation (GLO): The technological representativeness of this dataset is considered to be high as mining and concentration methods for zinc are consistent in all regions. Mining The mining of zinc ore includes underground and open cast mining processes. Within the global zinc industry, about 80% of zinc ore comes from underground mines and 20% from open pit or combination mines. - Underground Mining: Access is via vertical shafts or inclined roadways. There are usually two access routes (one for mining personnel and materials, and one for the ore) for safety and for ease of ventilation (fresh air comes in one and is then exhausted out of the other). These are permanent structures and therefore require strong roof supports (often including "bolts" into the rock to tie the layers together for strength). Once at the correct depth has been reached, horizontal tunnels are driven to reach the ore deposit. These are often temporary, so the support requirements are less substantial. Transport for personnel and materials can be by train, truck or conveyor belts. The largest share of the consumed fuels is diesel followed by electricity. Other major inputs include explosives and water. - Open Pit Mining: Hard-rock surface mining usually includes drilling, blasting, or a combination of both processes, and then lifting of the broken ore either into trucks or onto conveyors for transportation to the processing plant. This lifting is usually by excavator (electric or hydraulic; with shovel or backhoe configuration) or front-end loader. Benefication (Comminution and Flotation) Zinc ore is milled and mixed with water to recover a fine concentrate by gravity and elutriation techniques, creating a slurry. The separation process of the metal from the slurry is realized through the addition of various floatation chemicals.