GEMAS (Geochemical Mapping of Agricultural and Grazing Land Soil in Europe) ist ein Kooperationsprojekt zwischen der Expertengruppe „Geochemie“ der europäischen geologischen Dienste (EuroGeoSurveys) und Eurometeaux (Verbund der europäischen Metallindustrie). Insgesamt waren an der Durchführung des Projektes weltweit über 60 internationale Organisationen und Institutionen beteiligt. In den Jahren 2008 und 2009 wurden in 33 europäischen Ländern auf einer Fläche von 5 600 000 km² insgesamt 2219 Ackerproben (Ackerlandböden, 0 – 20 cm, Ap-Proben) und 2127 Grünlandproben (Weidelandböden, 0 – 10 cm, Gr-Proben) entnommen. In den Proben wurden 52 Elemente im Königswasseraufschluss, 41 Elemente als Gesamtgehalte sowie TC und TOC bestimmt. Ergänzend wurde in den Ap-Proben zusätzlich 57 Elemente in der mobilen Metallionenfraktion (MMI®) sowie die Bleiisotopenverhältnisse untersucht. Alle analytischen Untersuchungen unterlagen einer strengen externen Qualitätssicherung. Damit liegt erstmals ein qualitätsgesicherter und harmonisierter geochemischer Datensatz für die europäischen Landwirtschaftsböden mit einer Belegungsdichte von einer Probe pro 2 500 km² vor, der eine Darstellung der Elementgehalte und deren Bioverfügbarkeit im kontinentalen (europäischen) Maßstab ermöglicht. Die Downloaddateien zeigen die flächenhafte Verteilung der mit verschiedenen Analysenmetoden bestimmten Elementgehalte in Form von farbigen Isoflächenkarten mit jeweils 7 und 72 Klassen.
Computer länger zu nutzen, entlastet die Umwelt und senkt die Kosten, denn der größte Teil des Energie- und Ressourcenverbrauchs und der Umweltbelastung entsteht während der Herstellung der Computer und die Kosten für die Anschaffung sind entscheidend für die Gesamtkosten. Deshalb sollten Computer in der öffentlichen Verwaltung deutlich länger genutzt werden als bisher. Dadurch werden zudem wertvolle Ressourcen wie Silber, Gold, Palladium, Tantal, Gallium und Seltene Erden sorgsamer genutzt. Eine Broschüre gibt den Entscheidungsträgerinnen und Entscheidungsträgern in der Verwaltung Hinweise, wie sie durch die kluge Auswahl der richtigen Produkte und die gezielte Verlängerung der Nutzungsdauer Kosten sparen, die Umweltbelastung verringern und den Verwaltungsaufwand senken können. Veröffentlicht in Broschüren.
Zum Start der CeBIT: Neue Broschüre mit Verbraucher-Tipps Die Informations- und Kommunikationstechnik (IKT) ist das Rückgrat einer modernen Volkswirtschaft. Aber: Die Digitalisierung der Haushalte und Büros sowie das Internet verursachen einen erheblichen Strom- und Materialverbrauch. Allein in Deutschland sind rund zehn Kraftwerke nötig, um den Strombedarf der ITK in unseren modernen Haushalten zu decken. Ob Digitalkamera, Notebook, Spielkonsole, Handy oder Plasma-Fernseher, die ITK verursachte im Jahr 2007 rund 33 Millionen Tonnen des Klimagases Kohlendioxid (CO2) und damit mehr als der gesamte deutsche Luftverkehr. „Die Informations- und Kommunikationstechnik ist ein Wachstumsmarkt - und zwar auch beim Ausstoß klimaschädlicher Gase. Deshalb ist Klimaschutz hier besonders wichtig”, sagt Dr. Thomas Holzmann, Vizepräsident des Umweltbundesamtes (UBA). Zum Start der Computermesse CeBIT in Hannover am 3. März 2009 informiert das UBA in einer kostenlosen Verbraucher-Broschüre über Tipps und Kniffe beim Kauf energiesparender Computer, dem grünen Surfen und der umweltgerechten Aufrüstung alter Geräte. Computer mit gleicher Rechenleistung und Ausstattung verbrauchen leider oft unterschiedlich viel Energie. Wie bei Autos gibt es sowohl große Schlucker als auch Energiesparer. „Nicht nur Gigabyte und Pixel-Zahl sind beim Computerkauf entscheidend – auch auf den Energieverbrauch kommt es an. Jede Neuanschaffung legt den Energieverbrauch oft über Jahre fest. Wer beim Kauf genau hinschaut, wird belohnt”, erklärt Holzmann. Ein sehr effizienter Computer spart gegenüber einem ineffizienten Gerät zwischen 50 und 70 Prozent Strom. Dabei müssen sparsame Geräte nicht teurer sein als ineffiziente. Verbraucherinnen und Verbraucher sollten auch darauf achten, dass die neuen Geräte ihren individuellen Anforderungen entsprechen. Größer, schneller, stärker – kaum jemand will technisch zurückbleiben, wenn die neuen Geräte auf den Markt kommen. Aber: Was für die tatsächliche Nutzung überdimensioniert ist, braucht mehr Strom als nötig und ist meist teurer in der Anschaffung. „Und wer einen Rechner nur für Textverarbeitung und das Surfen nutzt, braucht sicher keinen Videoschnittplatz”, so der UBA -Vizepräsident. „Grüne” Informationstechnik hört übrigens nicht beim Energiesparen auf. Auch der Aufwand zur Herstellung der Geräte ist enorm: Für die Produktion eines einzigen PC samt Monitor sind rund 1.500 Liter Wasser und 23 Kilo verschiedener Chemikalien nötig. In den elektronischen Bauteilen stecken zudem seltene Metalle wie Gold, Silber, Tantal oder Platin, deren Förderung die Umwelt und die natürlichen Ressourcen belastet. PCs, Handys oder Laptops enthalten zudem Blei, Quecksilber und Cadmium und andere Stoffe, die die Gesundheit schädigen können. Alte Elektrogeräte gehören daher nicht in den Hausmüll, sondern sind getrennt zu sammeln und zu verwerten. Für die Verbraucherinnen und Verbraucher ist das völlig kostenlos: Sie können die Geräte bei den Sammelstellen der Städte und Gemeinden zurückgeben. Unter dem Motto „Nachhaltigkeit in einer digitalen Welt” informiert vom 3. bis 8. März 2009 die Green IT World auf der Messe CeBIT in Hannover. Das Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit ( BMU ), der Bundesverband Informationswirtschaft, Telekommunikation und neue Medien (BITKOM) und das Umweltbundesamt (UBA) präsentieren gemeinsam mit zahlreichen Unternehmen ökologisch und ökonomisch erfolgreiche IT-Innovationen – von Strom sparenden Notebooks über energieeffiziente Rechenzentren bis hin zu modernsten Videokonferenz-Lösungen. Eine gedruckte Fassung gibt es kostenlos beim Umweltbundesamt c/o GVP, Postfach 30 0361, 53183 Bonn oder telefonisch zum Ortstarif unter (03018) 305 3355 Besuchen Sie uns auf der CeBIT in Hannover in Halle 8, der „Green IT World”. Dessau-Roßlau, 02.03.2009
Die EU-Kommission legte am 26. Mai 2014 eine überarbeitete Liste kritischer Rohstoffe vor. Die Liste von 2014 umfasst 13 der 14 Stoffe aus der vorherigen Liste aus dem Jahr 2011 (Tantal wurde aufgrund eines geringeren Versorgungsrisikos herausgenommen). Außerdem sind sechs neue Rohstoffe hinzugekommen, nämlich Borate, Chrom, Kokskohle, Magnesit, Phosphatgestein und Silicium. Die Zahl der von der Europäischen Kommission als kritisch eingestuften Rohstoffe liegt also nunmehr bei 20. Bei den anderen 14 Rohstoffen handelt es sich um: Antimon, Beryllium, Flussspat, Gallium, Germanium, Graphit, Indium, Kobalt, Magnesium, Niob, Metalle der Platingruppe, schwere seltene Erden, leichte seltene Erden und Wolfram. Die Liste soll dabei helfen, einen Anreiz für die Erzeugung kritischer Rohstoffe in Europa zu schaffen und die Aufnahme neuer Abbau- und Recyclingtätigkeiten zu fördern. Darüber hinaus wird die Liste von der Kommission dazu verwendet, den vorrangigen Bedarf und entsprechende Maßnahmen zu ermitteln.
Systemraum: Erzgewinnung Tantalit bis Metallpulver in regionalen Lagern Geographischer Bezug: Weltmix Zeitlicher Bezug: 2000-2004 Weitere Informationen: Tantalgewinnung zu 10% aus Zinn-Schlacken, zu 60% aus Erzen; hier wird Gewinnung aus Tantalit/Pegmatit-Erzen betrachtet Die Bereitstellung von Investionsgütern wird in dem Datensatz nicht berücksichtigt. Allgemeine Informationen zur Förderung und Herstellung: Art der Förderung: Tagebau/Untertagebau Roherz-Förderung: Australien 61,4% Brasilien 18,1% Mosambik 5,8% Äthiopien 5,1% im Jahr 2006 Rohmetall-Herstellung: Daten proprietär Abraum: k.A.t/t Fördermenge: 1384t Ta-Gehalt Reserven: 43000t Ta-Gehalt Statische Reichweite: 31,1a
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 tantalum powder production, capacitor-grade (CN, RoW): After the production of tantalum concentrate (30% Ta2O5), it is digested at high temperature through the use of hydrofluoric and sulfuric acid. The produced Ta solution is filtered - thus removing the insoluble minerals – and then undergoes liquid-liquid separation (solvent extraction) using methyl isobutyl ketone (MIBK) to separate niobium from tantalum. The MIBK in tantalum is stripped from the solution and tantalum is precipitated as hydroxide by adding ammonia (NH3). Then, the hydroxide is calcined in a furnace to produce pure tantalum oxide. The pure tantalum oxide is later reduced to pure tantalum powder by bringing the pure tantalum oxide in contact with magnesium vapour, in a multiple hearth furnace or rotary kiln. The stoichiometric equation is the following: Ta2O5 + 5Mg -> 5MgO + 2Ta. The unreacted magnesium is assumed to be recovered. Sulfuric acid and ultrapure water are then utilized to remove the magnesium oxide, producing magnesium sulfate which is removed from the solution and therefore serves as a by-product that can be further processed.
Sondermetalle wie Neodym und weitere Seltenerdmetalle, Indium oder Tantal werden in Deutschland heute nicht oder nur in sehr eingeschränktem Maße aus Post-Consumer-Abfällen zurückgewonnen. Dies liegt zum Teil daran, dass viele der Produkte, die solche Metalle enthalten, noch nicht lange auf dem Markt sind, so dass sowohl der Aufbau von großtechnischen Recyclingverfahren noch nicht erfolgt ist als auch die Rücklaufmengen noch zu gering sind. Für die Rückgewinnung von Edelmetallen aus Abfällen gibt es zwar seit vielen Jahren bewährte Verfahren, eine Herausforderung stellt jedoch ihre effiziente Erfassung und Separation auch aus gering konzentrierten Abfallströmen aus einer Vielzahl kleiner Anfallstellen dar. Die Konzentration bzw. die Menge an Edel- und Sondermetallen in Altprodukten oder Bauteilen ist zudem häufig so gering, dass ihre Erfassung oder Separation aus den Abfallströmen aktuell nicht wirtschaftlich ist. Die Untersuchung befasste sich schwerpunktmäßig mit den Abfallströmen NdFeB-Magnete, Fahrzeug- elektronik, edelmetallhaltige Umweltkatalysatoren, cer- und lanthanhaltige Abfallströme, seltenerdmetallhaltige Leuchtstoffe, indiumhaltige LCD-Schichten und Tantalkondensatoren. Für diese Abfallströme wurde untersucht, wie neuartige Logistikkonzepte und Ansätze zur intelligenten Organisation sowie zur Gestaltung von Material- und Informationsflüssen das Recycling verbessern können. Es wurden technische, organisatorische und rechtliche Möglichkeiten zur längerfristigen Zwischenlagerung solcher Abfälle, bis großtechnische Recyclingverfahren verfügbar sind, konkretisiert und geprüft. Schließlich wurden Wege zur Abschätzung eines ökologisch optimalen Rückgewinnungsgrades erarbeitet und Maßnahmenvorschläge zur Erzielung von mehr Recycling entwickelt und bewertet. Quelle: Forschungsbericht
Sondermetalle wie Neodym und weitere Seltenerdmetalle, Indium oder Tantal werden in Deutschland heute nicht oder nur in sehr eingeschränktem Maße aus Post-Consumer-Abfällen zurückgewonnen. Dies liegt zum Teil daran, dass viele der Produkte, die solche Metalle enthalten, noch nicht lange auf dem Markt sind, so dass sowohl der Aufbau von großtechnischen Recyclingverfahren noch nicht erfolgt ist als auch die Rücklaufmengen noch zu gering sind. Für die Rückgewinnung von Edelmetallen aus Abfällen gibt es zwar seit vielen Jahren bewährte Verfahren, eine Herausforderung stellt jedoch ihre effiziente Erfassung und Separation auch aus gering konzentrierten Abfallströmen aus einer Vielzahl kleiner Anfallstellen dar. Die Konzentration bzw. die Menge an Edel- und Sondermetallen in Altprodukten oder Bauteilen ist zudem häufig so gering, dass ihre Erfassung oder Separation aus den Abfallströmen aktuell nicht wirtschaftlich ist. Die Untersuchung befasste sich schwerpunktmäßig mit den Abfallströmen NdFeB-Magnete, Fahrzeugelektronik, edelmetallhaltige Umweltkatalysatoren, cer- und lanthanhaltige Abfallströme, seltenerdmetallhaltige Leuchtstoffe, indiumhaltige LCD-Schichten und Tantalkondensatoren. Für diese Abfallströme wurde untersucht, wie neuartige Logistikkonzepte und Ansätze zur intelligenten Organisation sowie zur Gestaltung von Material- und Informationsflüssen das Recycling verbessern können. Es wurden technische, organisatorische und rechtliche Möglichkeiten zur längerfristigen Zwischenlagerung solcher Abfälle, bis großtechnische Recyclingverfahren verfügbar sind, konkretisiert und geprüft. Schließlich wurden Wege zur Abschätzung eines ökologisch optimalen Rückgewinnungsgrades erarbeitet und Maßnahmenvorschläge zur Erzielung von mehr Recycling entwickelt und bewertet. Quelle: Forschungsbericht
Das Projekt "Teilvorhaben 1: Konzeptentwicklung und Planung einer Pilotanlage für das Recycling von Tantal" wird vom Umweltbundesamt gefördert und von Fraunhofer-Institut für Silicatforschung (ISC), Projektgruppe für Wertstoffkreisläufe und Ressourcenstrategie (IWKS) durchgeführt. Das Übergangsmetall Tantal ist ein Element mit zahlreichen Anwendungsmöglichkeiten in der modernen Technik. Sein sehr hoher Schmelzpunkt von ca. 3000 °C und seine Korrosionsbeständigkeit machen es zu einem begehrten Werkstoff in der chemischen Industrie und der Medizintechnik. Das Hauptanwendungsgebiet liegt jedoch im Bereich Elektronik. Als namensgebender Bestandteil in Tantal-Kondensatoren ermöglicht das Übergangsmetall durch seine besonderen elektrischen Eigenschaften die Konstruktion von Bauteilen, die bei geringem Volumen eine sehr hohe elektrische Kapazität besitzen. Der Einsatz von Tantal-Kondensatoren erlaubt deshalb die Miniaturisierung von Elektrogeräten. Allerdings erfolgt die Förderung von Tantal zu erheblichen Teilen aus der politisch instabilen 'Große-Seen-Region' in Afrika und der Tantal-Abbau wird hier teilweise zur Finanzierung von kriegerischen Auseinandersetzungen genutzt. Deshalb wird dieses Tantal von der US-Börsenaufsichtsbehörde SEC als konfliktfördernd eingestuft. Um unbedenkliches Tantal verwenden zu können, muss entsprechend zertifiziertes - wie z.B. durch die OECD und die Conflict-Free Sourcing Initiative - erworben werden. Außerdem liegt die Recyclingquote von Tantal aus Altgeräten bei unter einem Prozent, da es auf dem herkömmlichen Kupferrecyclingweg verloren geht. Das Projekt IRETA, 'Entwicklung und Bewertung innovativer Recyclingwege zur Rückgewinnung von Tantal aus Elektronikabfällen', das mit rund 700.000 Euro im Rahmen der 'KMU-Innovationsoffensive Ressourcen- und Energieeffizienz' des BMBF gefördert wird, erforscht deshalb Recyclingwege, bei denen vollkommen neue Prozesswege im Zusammenhang mit Tantal zur Anwendung kommen. Dadurch soll eine Sekundärproduktion aufgebaut werden, die den Importbedarf von Tantal entsprechend senken wird. Dies bringt ökonomische Vorteile für die Industrie und trägt entscheidend zur Versorgungssicherheit Deutschlands bei. Der geplante Recyclingweg startet damit, dass die Tantal-Kondensatoren über eine optische Erkennungssoftware auf den Platinen von Elektroaltgeräten identifiziert und anschließend vollautomatisch demontiert werden. Anschließend folgt eine mechanische Aufbereitung der Kondensatoren zu einem Pulver. Mit drei verschiedenen innovativen Recyclingwegen, die auf chemischem Transport, funktionalisierten Nanopartikeln und elektrochemischer Abscheidung basieren, wird das Tantal aus diesem Pulver in Reinform wiedergewonnen. Eine vergleichende Bewertung der Recyclingwege unter ökonomischen und ökologischen Aspekten soll Aufschluss darüber geben, welcher dieser drei Prozesse für den Aufbau einer Pilotanlage infrage kommt.
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