Die US-Umweltorganisation Blacksmith Institute und die Umweltorganisation Green Cross Schweiz legen mit dem Umweltgiftbericht 2008 eine Liste der zehn weltweit gefährlichsten Umweltgifte vor. Mit ihrem Bericht wollen die Organisationen die Öffentlichkeit auf die schwerwiegenden Folgen durch Umweltgifte auf die menschliche Gesundheit aufmerksam machen. Laut Bericht sind die zehn gefährlichsten Umweltgiftquellen weltweit: Goldabbau; Kontaminierte Oberflächengewässer; Kontaminiertes Grundwasser; Luftschadstoffe in Innenräumen; Metallschmelzen und –verarbeitung; Industrieller Bergbau; Radioaktive Abfälle und Abfälle aus dem Uranbergbau; Ungeklärte Abwässer; Städtische Luftverschmutzung; Recycling von Bleibatterien
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 primary lead production from concentrate (GLO): There are two basic pyrometallurgical processes available for the production of lead from lead or mixed lead-zinc-sulphide concentrates: sinter oxidation / blast furnace reduction route or Direct Smelting Reduction Processes. Both processes are followed by a refining step to produce the final product with the required purity, and may also be used for concentrates mixed with secondary raw materials. SINTER OXIDATION / BLAST FURNACE REDUCTION: The sinter oxidation / blast furnace reduction involves two steps: 1) A sintering oxidative roast to remove sulphur with production of PbO; and 2) Blast furnace reduction of the sinter product. The objective of sintering lead concentrates is to remove as much sulphur as possible from the galena and the accompanying iron, zinc, and copper sulphides, while producing lump agglomerate with appropriate properties for subsequent reduction in the blast furnace (a type of a shaft furnace). As raw material feed, lead concentrates are blended with recycled sinter fines, secondary material and other process materials and pelletised in rotating drums. Pellets are fed onto sinter machine and ignited. The burning pellets are conveyed over a series of wind-boxes through which air is blown. Sulphur is oxidised to sulphur dioxide and the reaction generates enough heat to fuse and agglomerate the pellets. Sinter is charged to the blast furnace with metallurgical coke. Air and/or oxygen enriched air is injected and reacts with the coke to produce carbon monoxide. This generates sufficient heat to melt the charge. The gangue content of the furnace charge combines with the added fluxes or reagents to form a slag. For smelting bulk lead-zinc-concentrates and secondary material, frequently the Imperial Smelting Furnace is used. Here, hot sinter and pre-heated coke as well as hot briquettes are charged. Hot air is injected. The reduction of the metal oxides not only produces lead and slag but also zinc, which is volatile at the furnace operating temperature and passes out of the ISF with the furnace off-gases. The gases also contain some cadmium and lead. The furnace gases pass through a splash condenser in which a shower of molten lead quenches them and the metals are absorbed into the liquid lead, the zinc is refined by distillation. DIRECT SMELTING REDUCTION: The Direct Smelting Reduction Process does not carry out the sintering stage separately. Lead sulphide concentrates and secondary materials are charged directly to a furnace and are then melted and oxidised. Sulphur dioxide is formed and is collected, cleaned and converted to sulphuric acid. Carbon (coke or gas) and fluxing agents are added to the molten charge and lead oxide is reduced to lead, a slag is formed. Some zinc and cadmium are “fumed” off in the furnace, their oxides are captured in the abatement plant and recovered. Several processes are used for direct smelting of lead concentrates and some secondary material to produce crude lead and slag. Bath smelting processes are used: the ISA Smelt/Ausmelt furnaces (sometimes in combination with blast furnaces), Kaldo (TBRC) and QSL integrated processes are used in EU and Worldwide. The Kivcet integrated process is also used and is a flash smelting process. The ISA Smelt/Ausmelt furnaces and the QSL take moist, pelletised feed and the Kaldo and Kivcet use dried feed. REFINING: Lead bullion may contain varying amounts of copper, silver, bismuth, antimony, arsenic and tin. Lead recovered from secondary sources may contain similar impurities, but generally antimony and calcium dominate. There are two methods of refining crude lead: electrolytic refining and pyrometallurgical refining. Electrolytic refining uses anodes of de-copperised lead bullion and starter cathodes of pure lead. This is a high-cost process and is used infrequently. A pyrometallurgical refinery consists of a series of kettles, which are indirectly heated by oil or gas. Over a series of separation processes impurities and metal values are separated from the lead bouillon. Overall waste: The production of metals is related to the generation of several by-products, residues and wastes, which are also listed in the European Waste Catalogue (Council Decision 94/3/EEC). The ISF or direct smelting furnaces also are significant sources of solid slag. This slag has been subjected to high temperatures and generally contains low levels of leachable metals, consequently it may be used in construction. Solid residues also arise as the result of the treatment of liquid effluents. The main waste stream is gypsum waste (CaSO4) and metal hydroxides that are produced at the wastewater neutralisation plant. These wastes are considered to be a cross-media effect of these treatment techniques but many are recycled to pyrometallurgical process to recover the metals. Dust or sludge from the treatment of gases are used as raw materials for the production of other metals such as Ge, Ga, In and As, etc or can be returned to the smelter or into the leach circuit for the recovery of lead and zinc. Hg/Se residues arise at the pre-treatment of mercury or selenium streams from the gas cleaning stage. This solid waste stream amounts to approximately 40 - 120 t/y in a typical plant. Hg and Se can be recovered from these residues depending on the market for these metals. Overall emissions: The main emissions to air from zinc and lead production are sulphur dioxide, other sulphur compounds and acid mists; nitrogen oxides and other nitrogen compounds, metals and their compounds; dust; VOC and dioxins. Other pollutants are considered to be of negligible importance for the industry, partly because they are not present in the production process and partly because they are immediately neutralised (e.g. chlorine) or occur in very low concentrations. Emissions are to a large extent bound to dust (except cadmium, arsenic and mercury that can be present in the vapour phase). Metals and their compounds and materials in suspension are the main pollutants emitted to water. The metals concerned are Zn, Cd, Pb, Hg, Se, Cu, Ni, As, Co and Cr. Other significant substances are fluorides, chlorides and sulphates. Wastewater from the gas cleaning of the smelter and fluid-bed roasting stages are the most important sources. References: Sutherland C. A., Milner E. F., Kerby R. C., Teindl H. and Melin A. (1997) Lead. In: Ullmann's encyclopedia of industrial chemistry (ed. Anonymous). 5th edition on CD-ROM Edition. Wiley & Sons, London. IPPC (2001) Integrated Pollution Prevention and Control (IPPC); Reference Document on Best Available Techniques in the Non Ferrous Metals Industries. European Commission. Retrieved from http://www.jrc.es/pub/english.cgi/ 0/733169 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 treatment of electronics scrap, metals recovery in copper smelter (SE, RoW): Conversion of Copper in a Kaldo Converter and treatment in converter aisle. technologyComment of treatment of scrap lead acid battery, remelting (RoW): The referred operation uses a shaft furnace with post combustion, which is the usual technology for secondary smelters. technologyComment of treatment of scrap lead acid battery, remelting (RER): The referred operation uses a shaft furnace with post combustion, which is the usual technology for secondary smelters. Typically this technology produces 5000 t / a sulphuric acid (15% concentration), 25’000 t lead bullion (98% Pb), 1200 t / a slags (1% Pb) and 3000 t / a raw lead matte (10% Pb) to be shipped to primary smelters. Overall Pb yield is typically 98.8% at the plant level and 99.8% after reworking the matte. The operation treats junk batteries and plates but also lead cable sheathing, drosses and sludges, leaded glass and balancing weights. From this feed it manufactures mainly antimonial lead up to 10% Sb, calcium-aluminium lead alloys with or without tin and soft lead with low and high copper content. All these products are the result of a refining and alloying step to meet the compliance with the designations desired. The following by products are reused in the process: fine dust, slag, and sulfuric acid. References: Quirijnen L. (1999) How to implement efficient local lead-acid battery recycling. In: Journal of Power Sources, 78(1-2), pp. 267-269.
technologyComment of manganese production (RER): The metal is won by electrolysis (25%) and electrothermic processes (75%). ELECTROLYSIS OF AQUEOUS MANGANESE SALTS The production of manganese metal by the electrolysis of aqueous manganese salts requires at first a milling of the manganese ore. Milling increases the active surface and ensures sufficient reactivity in both the reduction and the subsequent leaching steps. After milling the manganese ore is fed to a rotary kiln where the reduction and calcination takes place. This process is carried out at about 850 - 1000 ºC in a reducing atmosphere. As a reducing agent, several carbon sources can be used e.g. anthracite, coal, charcoal and hydrocarbon oil or natural gas. The cal-cined ore needs to be cooled below 100 ºC to avoid a further re-oxidation. The subsequent leaching process is carried out with recycled electrolyte, mainly sulphuric acid. After leaching and filtration the iron content is removed from the solution by oxidative precipitation and the nickel and cobalt are removed by sulphide precipitation. The purified electrolyte is then treated with SO2 in order to ensure plating of γ-Mn during electrolysis. Electrolysis is carried out in diaphragm cells. The cathode is normally made of stainless steel or titanium. For the anode lead-calcium or lead-silver alloy can be used. After an appropriate reaction time the cathodes are removed from the electrolysis bath. The manganese that is deposited on the cathode starter-sheet is stripped off mechanically and then washed and dried. The metal is crushed to produce metal flakes or powder or granulated, depending on the end use. ELECTROTHERMAL DECOMPOSITION OF MANGANESE ORES The electrothermal process is the second important process to produce manganese metal in an industrial scale. The electrothermal process takes place as a multistage process. In the first stage manganese ore is smelted with only a small amount of reductant in order to reduce mostly the iron oxide. This produces a low-grade ferro-manganese and a slag that is rich in Mn-oxide. The slag is then smelted in the second stage with silicon to produce silicomanganese. The molten silicomanganese can be treated with liquid slag from the fist stage to obtain relatively pure manganese metal. For the last step a ladle or shaking ladle can be used. The manganese metal produced by the electrothermal process contains up to 98% of Mn. Overall emissions and waste: Emissions to air consist of dust and fume emissions from smelting, hard metal and carbide production; Other emissions to air are ammonia (NH3), acid fume (HCl), hydrogen fluoride (HF), VOC and heavy metals. Effluents are composed of overflow water from wet scrubbing systems, wastewater from slag and metal granulation, and blow down from cooling water cycles. Waste includes dust, fume, sludge and slag. References: Wellbeloved D. B., Craven P. M. and Waudby J. W. (1997) Manganese and Manganese Alloys. In: Ullmann's encyclopedia of industrial chemistry (ed. Anonymous). 5th edition on CD-ROM Edition. Wiley & Sons, London. IPPC (2001) Integrated Pollution Prevention and Control (IPPC); Reference Document on Best Available Techniques in the Non Ferrous Metals Industries. European Commission. Retrieved from http://www.jrc.es/pub/english.cgi/ 0/733169 technologyComment of manganese production (RoW): The metal is won by electrolysis (assumption: 25%) and electrothermic processes (assumption: 75%). No detailed information available, mainly based on rough estimates. technologyComment of treatment of non-Fe-Co-metals, from used Li-ion battery, hydrometallurgical processing (GLO): The technique SX-EW is used mainly for oxide ores and supergene sulphide ores (i.e. ores not containing iron). It is assumed to be used for the treatment of the non-Fe-Co-metals fraction. The process includes a leaching stage followed by cementation or electro-winning. A general description of the process steps is given below. In the dump leaching step, copper is recovered from large quantities (millions of tonnes) of strip oxide ores with a very low grade. Dilute sulphuric acid is trickled through the material. Once the process starts it continues naturally if water and air are circulated through the heap. The time required is typically measured in years. Sulphur dioxide is emitted during such operations. Soluble copper is then recovered from drainage tunnels and ponds. Copper recovery rates vary from 30% to 70%. Cconsiderable amounts of sulphuric acid and leaching agents emit into water and air. No figures are currently available on the dimension of such emissions. After the solvent-solvent extraction, considerable amounts of leaching residues remain, which consist of undissolved minerals and the remainders of leaching chemicals. In the solution cleaning step occur precipitation of impurities and filtration or selective enrichment of copper by solvent extraction or ion exchange. The solvent extraction process comprises two steps: selective extraction of copper from an aqueous leach solution into an organic phase (extraction circuit) and the re-extraction or stripping of the copper into dilute sulphuric acid to give a solution suitable for electro winning (stripping circuit). In the separation step occurs precipitation of copper metal or copper compounds such as Cu2O, CuS, CuCl, CuI, CuCN, or CuSO4 • 5 H2O (crystallisation) Waste: Like in the pyrometallurgical step, considerable quantities of solid residuals are 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 (iron hydroxide, 60% water, cat I industrial waste).
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 platinum group metal mine operation, ore with high palladium content (RU): imageUrlTagReplace6250302f-4c86-4605-a56f-03197a7811f2 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 processing of nickel-rich materials (GLO): Based on typical current technology. 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 smelting and refining of nickel concentrate, 7% Ni (CN): The nickel concentrate (6.78% beneficiated - product of the mining and beneficiation processes) undergoes drying, melting in flash furnace and converting to produce high nickel matte. The nickel matte undergoes grinding-floating separation and is refined through anode plate casting and electrolysis in order to produce electrolytic nickel 99.98% pure. Deng, S. Y., & Gong, X. Z. (2018). Life Cycle Assessment of Nickel Production in China. Materials Science Forum, 913, 1004-1010. doi:10.4028/www.scientific.net/MSF.913.1004 technologyComment of treatment of metal part of electronics scrap, in copper, anode, by electrolytic refining (SE, RoW): Production of cathode copper by electrolytic refining.
technologyComment of electrolysis of lithium chloride (GLO): Lithium chloride electrolysis is the only process to produce lithium metal. Lithium metal is produced by the electrolysis of molten lithium chloride, whose melting point of 614 °C is lowered by addition of potassium chloride. The lithium chloride – potassium chloride eutectic, with 44.3 % lithium chloride, melts at 352 °C. The salt mixtures used in industry contain 45 – 55 % lithium chloride, which allows electrolysis to be carried out at 400 – 460 °C. 2 LiCL → 2 Li + Cl2 The electrolytic cells most commonly employed resemble the Downs cell used for the produc-tion of sodium, although the American lithium electrolytic cell and other special cells may be used. Wietelmann, U., Bauer, R.: Lithium and Lithium Compounds. Published online: 2000. In: Ullmann's Encyclopedia of Industrial Chemistry, Seventh Edition, 2004 Electronic Release (ed. Fiedler E., Grossmann G., Kersebohm D., Weiss G. and Witte C.). 7 th Electronic Release Edition. Wiley InterScience, New York, Online-Version under: http://www.mrw.interscience.wiley.com/emrw/9783527306732/home
Das Projekt "Sanduntersuchung BW/w" wird vom Umweltbundesamt gefördert und von IfG - Institut für Gießereitechnik gGmbH durchgeführt. Vermeidung und Verwertung von Giessereireststoffen
Das Projekt "Behaviour of actinides and other radionuclides that are difficult to measure, in melting of steel" wird vom Umweltbundesamt gefördert und von Kraftwerk Union AG durchgeführt. Objective: various types of contaminated piping, valves, heat exchangers and vessels are removed from nuclear facilities in the course of decommissioning. Depending on their origin, these components are contaminated with various radio nuclides, e.g. alpha-emitters, pure beta-emitters, and gamma-emitters. Unrestricted or otherwise non-hazardous reuse of these components is possible if the residual activity concentrations are below the limits authorised. To achieve this goal, decontamination processes have to be used in general. In many cases, chemical decontamination of large components with complex surface geometry cannot be performed economically. Recycling can be achieved in many cases using melting processes. Thus the non-hazardous reuse of beta-, gamma-contaminated material which accumulated in the course of repairs and refittings of nuclear power plants has been demonstrated by the contractor in co-operation with Siempelkamp Giesserei GmbH und Co, Krefeld. The aim of this research programme is to extend the melt decontamination process to materials which are contaminated with actinides and radio nuclides that are difficult to measure. The distribution of these radio nuclides in the metal and the slag will be determined and direct measuring techniques or representative sampling techniques will be developed. General information: b.1. Literature review related to radio nuclide deposition on components, chemical separation procedures for iron and nickel, basic radio nuclide data and evaluation of authorised activity limits. B.2. Sampling of material and test melts at laboratory scale using well known activity quantities and accompanied by an appropriate measurement programme for original material, metal, slag and off-gas. B.3. Development of direct measuring techniques for alpha emitters in melt and slag, taking into account the alpha-energy of the emitting nuclides and the sample geometry. B.4. Development of measuring techniques for pure beta-emitters, such as c-14 and sr-90, expected to be found in metal and off-gas, and in slag, respectively. B.5. Development of a sampling technique and simple chemical separation procedures for nuclides decaying by electron capture, such as fe-55 and ni-59, emitting weak x-rays which cannot be measured directly. B.6. Large-scale melt in a commercial foundry of alpha-contaminated material to demonstrate the transferability of the laboratory results to industrial scale. B.7. Evaluation of results from both laboratory tests and large-scale tests with respect to alpha-activity distribution in metal, slag and off-gas, the most suitable measuring technique and costs. Achievements: the research work carried out confirmed the expected homogeneous distribution of the radio nuclides selected for the experiments (iron-55 and nickel-63) in the metal ingot, as was already known from the behaviour of cobalt-60. Cobalt-60 radio nuclide may be used as an indicator nuclide for iron-55 and nickel-63 which are both ...
Das Projekt "Raising the Lifetime of Functional Materials for Concentrated Solar Power Technology (RAISELIFE)" wird vom Umweltbundesamt gefördert und von Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) durchgeführt. RAISELIFE is a project funded by the European Union's Horizon 2020 research and innovation programme coordinated by Deutsches Zentrum für Luft- und Raumfahrt at Cologne, Germany. RAISELIFE addresses the challenges of materials for CSP technology focusing on the 2020 targets stated in the Materials Roadmap (SEC(2011)1609). For this purpose the project brings together a broad consortium formed of leading industry partners, SMEs, and research institutes in the concentrated solar thermal and materials science sector. The project scope has been significantly shaped by the leading Engineering, Procurement and Construction (EPC) of ST technology BSII. This unique constellation permits a direct transfer of the results obtained in RAISELIFE to new commercial CSP plants within less than 5 years. This project focuses on raising the lifetime of five key functional materials for concentrated solar power (CSP) technologies: 1) protective and anti-soiling coatings for primary reflectors, 2) very high-reflective surfaces for heliostats, 3) high-temperature secondary reflectors, 4) receiver coatings, and 5) corrosion-resistant high-temperature metals and coatings for molten salts. At DFI new coatings for different applications will be developed. On the one hand new high absorptivity diffusion coatings based on manganese and chromium will be applied on different steels and nickel-based alloys as material for receivers. The formed black oxide scales must exhibit high absorptivity, low emissivity, and good resistance against corrosion and thermal shock. The coated materials will be tested in different laboratories of the project partners for high temperature and water-based corrosion. On the other hand the solar energy has to be transferred to a medium such as steam of molten salts. Therefore diffusion coatings for the inside of the absorber tubes on the base of chromium and nickel will be applied on the same materials. The coatings will be investigated in static and dynamic molten salt conditions at different temperatures and impurity levels in order to understand the corrosion and failure mechanisms precisely.
Das Projekt "Untersuchungen zum Schmelzen von radioaktivem Altmetall in einem kontrollierten Bereich" wird vom Umweltbundesamt gefördert und von Noell durchgeführt. Objective: the melting of radioactive metal waste has several advantages in comparison with other procedures, i.e.: reduction of the waste volume to be disposed of, safe enclosure of the radio nuclide in the metal matrix safe and exact determination of the radioactive inventory and, under certain conditions, harmless reuse of the metal. The aim of the investigations is the testing of the melting procedure on various types of waste metal, with surface contamination up to 500 bq/cm2 and specific activity up to 200 bq/g, under permanent operation conditions and in a controlled area. General information: b.1. Investigations on the distribution of radio nuclides in melt, slag, furnace liner and filter dust. B.2. Investigations on secondary waste, in function of the processed material, and on behaviour of the filter system. B.3. Investigations on committed doses and activity release as consequences of the melting work. B.4. Overall evaluation of the melting technique and comparison with alternative techniques (decontamination, compaction, direct disposal.). Achievements: the melting of 200 t of various highly contaminated steel wastes (200 bq/g and 500 bq/cm(2)) was not completed because the melting plant was prematurely decommissioned by the Kernforschungszentrum Karlsruhe, for economic reasons. In the work completed, however, it was found that cobalt-60 and other iron like nuclides remained, as expected, almost completely in the ingot, whereas caesium-137 and europium-152 were concentrated in the slag. In spite of the short operation time, it was shown that long term operation of the melting plant would be possible without significant radiation exposure to the workforce.
Das Projekt "Neues kontinuierliches Schmelz- und Raffinationsverfahren fuer Kupfer" wird vom Umweltbundesamt gefördert und von Norddeutsche Affinerie durchgeführt. Objective: The rising costs of energy and labour together with stringent environmental protection requirements have led to the development of new methods for non-ferrous metal extraction, in which there is a trend towards continuous production plants with a high specific output. Contimelt is a new two-stage process for melting and refining copper. Compared to the traditional batch wise operated reverberatory refining furnace, Contimelt represents a continuous operation with a high melting/refining rate, saving energy and man-hours and allowing close environmental control. General Information: Contimelt consists of two processing stages: the anode shaft furnace, in which the Cu-feed material (blister copper, anode scrap, copper scrap) is melted and refined, and the poling furnace, in which copper is poled (deoxidized) in a continuous flow. The molter copper is cast to anodes to be electrolytic ally refined in the tank house. ANODE SHAFT FURNACE (ASF). The anode shaft furnace consists of a small hearth furnace with a mounted shaft. The hot off-gases flow through the feed material in the shaft and heat it up in a counter current flow. As a result energy is saved in comparison with the conventional method. The firing system is divided into 3 burner sections (one of which is a pure oxygen-burner). The sections function independently of each other. By having one or more burners out of operation each area in the furnace can, as required, be heated to a different level. The melting rate of the anode shaft furnace lies in the region of 50-100 t/h according to the ease of melting the charge and the oxygen enrichment.. The slag tapping opening is in the superheating area of the hearth furnace through which the slag is skimmed. The copper is tapped continuously and flows via a launder into the drum-type poling furnace. POLING AND CASTING FURNACE (PCF). The copper with a high oxygen content melted in the anode shaft furnace is deoxidized from 6000 g/t or even 9000 g/t to less than 1000 g/t of oxygen in the poling furnace. The poling furnace has a holding capacity of up to 80 tonnes of copper. The off-gas with a high proportion of unburnt gases is then after burnt in a La-Mont boiler. Two tuyeres using natural gas operate under the bath to pole the copper. The tuyeres and the tap hole are situated so that poling and casting is continuous. The volume of poling gas that can be employed per tuyere is about 250 Nm3/h natural gas. The poled copper flows through a launder to two anode casting wheels. OFF-GAS SYSTEM. For off-gas handling from the ASF and the PCF three ventilators with a total 140,000 m3/h suction rate are available, of which one is installed behind the waste heat boiler and the other two behind the filter. A waste heat boiler and air preheater system is used to cool the combined off-gases of the ASF and PCF. The off-gases are finally ducted through a fresh air cooler, in which the off-gas temperature is further reduced by 80 to 100 deg C., and ...