Zink ist ein für Pflanze, Tier und Mensch essentielles Spurenelement, welches jedoch bei extrem hohen Gehalten auf Pflanzen und Mikroorganismen toxisch wirken kann. Die Zn-Konzentration in der oberen kontinentalen Erdkruste (Clarkewert) beträgt 52 mg/kg, sie kann aber in Abhängigkeit vom Gesteinstyp stark schwanken. Die mittleren Zn-Gehalte (Median) der sächsischen Hauptgesteinstypen liegen zwischen 11 bis 140 mg/kg, der regionale Clarke des Erzgebirges beträgt ca. 79 mg/kg. Sphalerit (Zinkblende) führende polymetallische La-gerstätten können lokal zu zusätzlichen geogenen Zn-Anreicherungen in den Böden führen. Anthropogene Zn-Einträge erfolgen vor allem durch die Eisen- und Buntmetallurgie bzw. durch die Zn-verarbeitenden Industrien (Farben, Legierungen, Galvanik) und durch Großfeuerungsanlagen. Im Bereich von Ballungsgebieten sind Zn-Anreicherungen relativ häufig zu beobachten. Anthropogene Zn-Einträge sind in der Landwirtschaft durch die Verwendung von organischen und mineralischen Düngemitteln möglich. Für unbelastete Böden gelten Zn-Gehalte von 10 bis 80 mg/kg als normal. Die regionale Verbreitung der Zn-Gehalte in den sächsischen Böden wird vor allem durch die geogene Prägung der Substrate bestimmt; niedrige bis mittlere Gehalte sind über den periglaziären Sanden und Lehmen im Norden und den Lössböden in Mittelsachsen (10 bis 50 mg/kg) sowie den Verwitterungsböden über den Festgesteinen des Erzgebirges/Vogtlandes (50 bis 150 mg/kg) zu erwarten. Innerhalb der Grundgebirgseinheiten treten über den polymetallischen Lagerstätten des Erzgebirges, in Abhängigkeit von der Intensität der Vererzung, deutliche positive Zn-Anomalien auf (Freiberg, Annaberg-Buchholz - Marienberg, Aue - Schwarzenberg). Böden über Substraten mit extrem niedrigen Zn-Gehalten (Granit von Eibenstock, Orthogneise der Erzgebirgs-Zentralzone, Osterzgebirgischer Eruptivkomplex, kretazische Sandsteine) treten als negative Zn-Anomalien im Kartenbild in Erscheinung. Verstärkte Zn-Akkumulationen sind in den Auenböden des Muldensystems festzustellen. Auf Grund der höheren geogenen Grundgehalte im Wassereinzugsgebiet, dem Auftreten Zn-führender polymetallischer Vererzungen und insbesondere der Bergbau- und Hüttentätigkeit im Freiberger Raum, kommt es vor allem in den Auenböden der Freiberger und Vereinigten Mulde zu hohen Zn-Konzentrationen (Mediangehalte 370 bzw. 240 mg/kg). Für die Wirkungspfade Boden-Mensch sowie Boden-Pflanze wurden keine Prüf- und Maßnahmenwerte für Gesamtgehalte in der Bundes-Bodenschutz- und Altlastenverordnung (BBodSchV) festgeschrieben, da Zn bei der Gefahrenbeurteilung nur von geringer Bedeutung ist.
Ab Dezember 2011 ist Cadmium in Schmuck, Legierungen zum Löten und in PVC in der EU verboten. Die neuen Rechtsvorschriften verbieten Cadmium in jeder Art von Schmuck, nur alte Schmuckstücke sind hiervon ausgenommen. Das Verbot gilt überdies für alle Kunststoffe und für Legierungen zum Verlöten unterschiedlicher Metalle. Das Cadmiumverbot fügt sich in die REACH-Strategie der EU für einen sichereren Einsatz von Chemikalien. Nicht nur sind durch das Cadmiumverbot Verbraucherinnen und Verbraucher in der EU besser geschützt, auch die Umwelt wird weniger stark belastet. Das Verbot wird über eine Änderungsverordnung zur REACH-Verordnung umgesetzt. Die neuen Vorschriften verbieten Cadmium in jeder Art von Kunststoff und unterstützen gleichzeitig die Verwendung von Recycling-PVC in zahlreichen Bauprodukten. Da PVC ein wertvolles Material ist, das mehrfach wiedergewonnen werden kann, ist für eine Reihe von Bauprodukten die Wiederverwendung von PVC-Abfall mit niedrigem Cadmiumgehalt ohne Gefahr für Gesundheit oder Umwelt erlaubt. Das neue Verbot wird in Anhang XVII der REACH-Verordnung aufgenommen (Verordnung (EG) Nr. 1907/2006 zur Registrierung, Bewertung, Zulassung und Beschränkung chemischer Stoffe).
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
The project "KartAL III - Mapping of the Anthropogenic Stock III", commissioned by the Federal Environment Agency, focuses on the recovery options and expected material flows of seven metals and its alloys. In order to significantly improve the circular economy through urban mining in Germany, the potentials, approaches and success factors of relevant stakeholders identified in the project were compiled in a guide. Veröffentlicht in Leitfäden und Handbücher.
"Rare earths are to China what oil is to the Middle East," stated Deng Xiaoping in 1992 (Wang 2007). China accounts for 97 percent of global rare earth production, and as such the world is more dependent on it than it is on oil from the Middle East. That situation is significant because rare earths, although usually used only in small amounts, are of great strategic relevance. They are not only key components of many military technologies, including guided missiles and radar; they are also to be found in many high-tech products which we use in our daily lives – primarily electronic devices such as computer hard disks, plasma screens and MP3 players. They also make alloys harder, and are used to grind precision lenses. Veröffentlicht in Texte | 31/2011.
Mittels Urban Mining, der Gewinnung von Sekundärrohstoffen aus langlebigen Gütern wie Infrastrukturen, Bauwerken, Industriegütern und Haushaltsgeräten, werden Primärrohstoffe eingespart und Umweltbelastungen über die gesamte Wertschöpfungskette robust reduziert. Das im Auftrag von Umweltbundesamt und BMUV durchgeführte Vorhaben „KartAL III - Kartierung des Anthropogenen Lagers III“ fokussiert die Verwertungswege und erwarteten Stoffströme von sieben Metallen bzw. ihren Legierungen und neun mineralischen Baustoffen. Für beide Materialgruppen werden wachsende Potenziale und Stellgrößen aufgezeigt, um die Kreislaufwirtschaft durch Urban Mining in Deutschland nennenswert zu verbessern. Die wesentlichen Ergebnisse und Handlungsansätze des Projekts sind in Leitfäden zusammengestellt. Veröffentlicht in Texte | 47/2022.
Das im Auftrag des Umweltbundesamtes durchgeführte Vorhaben „KartAL III - Kartierung des Anthropogenen Lagers III“ fokussiert die Verwertungswege und erwarteten Stoffströme von sieben Metallen und ihren Legierungen. Um die Kreislaufwirtschaft durch Urban Mining in Deutschland nennenswert zu verbessern, werden die im Projekt identifizierten Potenziale, Stellgrößen und Handlungsansätze in einem Leitfaden überblicksartig zusammengestellt. Veröffentlicht in Leitfäden und Handbücher.
„Rare earths are to China what oil is to the Middle East,” verkündete Deng Xiaoping 1992 (Wang 2007). Mit einem Marktanteil von 97 Prozent der globalen Produktion ist die Welt heute abhängiger von den Seltenen Erden Chinas als vom Öl des Mittleren Ostens. Diese Entwicklung ist von Bedeutung, da Seltene Erden, obwohl sie meist nur in kleinen Mengen verwendet werden, von größter strategischer Relevanz sind. Sie sind nicht nur wichtiger Bestandteil vieler Militärtechnologien, wie Lenkraketen und Radar, sondern stecken auch in vielen Hochtechnologien unseres täglichen Lebens; v.a. in Elektronikgeräten, wie Festplatten, Plasmabildschirmen und MP3-Spielern. Ebenso machen sie Legierungen härter und schleifen Präzisionslinsen. Veröffentlicht in Texte | 26/2011.
Nickel gilt für manche Tiere, Pflanzen und Mikroorganismen als essentielles Spurenelement; für den Menschen ist dies nicht sicher nachgewiesen. Die Ni-Konzentration in der oberen kontinentalen Kruste (Totalgehalte) beträgt 19 mg/kg, kann aber in den unterschiedlichen Gesteinstypen stark schwanken. Die mittleren Ni-Gehalte (Median) der sächsischen Hauptgesteinstypen variieren von 1 bis 1 900 mg/kg, der regionale Clarke des Erzgebirges/Vogtlandes beträgt 23 mg/kg. Für unbelastete Böden gelten Ni-Gehalte von 5 bis 50 mg/kg als normal. Zusätzliche geogene Ni-Anreicherungen in Böden sind vor allem im Bereich der Ni-Verwitterungslagerstätten (Haupterzmineral Garnierit) über Serpentiniten im Granulitgebirge und dessen Schiefermantel anzutreffen, die jedoch nur geringe Flächen einnehmen. Bei den Ganglagerstätten besitzen die Vererzungen der Quarz-Arsenid-Assoziation ("Bi-Co-Ni-Ag-U-Formation") eine nur geringe umweltgeochemische Relevanz. Auch ein Einfluss der Ni-Mineralisation von Sohland/Spree ist im vorliegenden Maßstab nicht erkennbar. Anthropogene Ni-Einträge erfolgen vor allem durch die Eisenmetallurgie bzw. durch Ni-verarbeitende Industrien (Legierungen, Apparatebau, Lacke, Kunststoffe) und durch die Verbrennung fossiler Energieträger. Weitere nennenswerte Ni-Einträge sind vor allem mit den Abwässern in aquatische Ökosysteme möglich (z. B. Klärschlamm). Die regionale Verbreitung erhöhter Ni-Gehalte in den sächsischen Böden wird vor allem durch die geogene Spezialisierung der Substrate bestimmt. Aufgrund der erhöhten Ni-Gehalte der Serpentinite (1 900 mg/kg), der tertiären Basalte (120 mg/kg), Amphibolite und Gabbros (110 mg/kg) und der devonischen Diabase (80 mg/kg) kommt es entsprechend der Verbreitung dieser Substrate, teils zu flächenhaften, teils zu punktförmigen anomal hohen Ni-Gehalten im Oberboden. Durch Einschaltungen von Metabasiten in die Phyllit- und Glimmerschieferfolgen, sowie wegen der schwach erhöhten Ni-Gehalte in diesen Gesteinen selbst (30 bis 40 mg/kg), treten das Vogtland und das Westerzgebirge als Gebiete erhöhter Ni-Gehalte im Kartenbild deutlich in Erscheinung. Analog zum Cr, kommen über den Substraten der sauren Magmatite und Metamorphite, der Sandsteine der Elbtalkreide sowie der periglaziären Decksedimente die niedrigsten Ni-Gehalte in den Böden vor. Bei den Auenböden lassen sich hinsichtlich der Ni-Gehalte deutliche Beziehungen zum geologischen Bau der Gewässereinzugsgebiete erkennen. Während in den Auenböden der Weißen Elster, des Muldensystems und der Elbe (Einzugsgebiet Erzgebirge, Vogtland) mittlere und z. T. schwach erhöhte Gehalte auftreten, sind die Auenböden u. a. der Schwarzen Elster und Spree (Einzugsgebiet Lausitz) relativ Ni-arm. Dazu tragen sicher auch die geringere Besiedlungsdichte und die niedrigere Dichte von Industriestandorten in der Lau-sitz bei. Problematisch ist die Umrechnung von Ni-Totalgehalten in Ni-Königswassergehalte (KW). Praktische Erfahrungen bei den Bodenuntersuchungen zeigen, dass die KW-Gehalte gegenüber den Totalgehalten in Abhängigkeit von der Bindungsform in den Substraten um ca. 10 bis 30 % niedriger sind. Die in der Bundes-Bodenschutz- und Altlastenverordnung (BBodSchV) festgelegten Prüfwerte für den Wirkungspfad Boden-Mensch (KW-Gehalte) werden in Sachsen nur z. T über den Diabasen und den kleinräumig auftretenden Serpentiniten überschritten. Gefährdungen können aber hier weitgehend ausgeschlossen werden, da das Ni silikatisch gebunden vorliegt und eine Freisetzung nicht zu befürchten ist. Der Ni-Transfer Boden-Pflanze auf Grünlandflächen ist unbedeutend; der Maßnahmenwert von 1 900 mg/kg wird nicht erreicht.
Helm, Dieter Science of the Total Environment 299 (2002), 1-3, 247 - 249 The German Environmental Specimen Bank found that students suffering from diseases of the thyroid or the immune system had increased palladium urinary values compared to healthy individuals. Since the immunotoxic features of palladium are well known, there may be a causal relationship. Sources of palladium were identified as dental alloys, the chemical industry, oil- or coal-driven power plants and the consumption of meat products. doi:10.1016/S0048-9697(02)00274-7g
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