Smelter

The element is commercially obtained from the dusts of smelters processing zinc ores, as well as recovered from combustion by-products of certain coals. A large reserve of the elements for future uses in insured in coal sources. 

Smelling salts Smell receptors Smelters Smelting... 

Water Groundwater can be treated in anaerobic bioreactors that encourage the growth of sulfate reducing bacteria, where the metals are reduced to insoluble sulfides, and concentrated in the sludge. For example, such a system is in use to decontaminate a zinc smelter site in the Netherlands (95). 

The principal producers of aluminum trifluoride in North America are Alcan, Alcoa, and AUiedSignal. It is also produced in other countries, eg, France, Mexico, Norway, Italy, Tunisia, and Japan. Total worldwide production of aluminum trifluoride in 1990 was 400,000 metric tons and the price was 1100/t. In 1993, because of excess recovery of fluorine values, use of energy efficient smelters, and the worldwide economic climate, the price was down to 750/t. 

Sintering. The charge for sintering is prepared by blending selected concentrates, smelter by-products, returned sinter, flue dust, and when required, additional fuel such as coke bree2e. The blend is then peUeti2ed in preparation for sintering. 

If antimony and arsenic are present ia the feed, copper and iron react to form the respective antimonides and arsenides known as speiss (specific gravity 6.0). If it is preferred to remove copper ia a speiss layer, the sulfur ia the siater must be reduced and the addition of scrap iron may be necessary to encourage speiss formation. Matte and speiss are usually sent to a copper smelter for recovery of the metals. 

As of 1992, eight smelters used the Imperial smelting process (Fig. 4), but none within the United States. The essential reactions taking place for smelting are... 

Owing to the cycHc nature of the TBRC operation, waste heat recovery from the off-gases is not practical and the SO2 content of the gas varies with the converter cycle. In order to supply a relatively uniform flow and strength SO2 gas to a sulfuric acid plant, a system has been installed at RonnskAr whereby the SO2 from fluctuating smelter gases is partially absorbed in water. During smelter gas intermption, SO2 is stripped with air and the concentrated gas deflvered to the acid plant. 

The continuous softening process used by The Broken Hill Associated Smelters Pty., Ltd. is particularly suitable for lead buUion of fairly uniform impurity content. The copper-drossed blast furnace buUion continuously flows in the feed end of a reverberatory furnace at 420°C, and the softened lead leaves the opposite end at 750°C. Oxidation and agitation is provided by compressed air blown through pipes extending down through the arch of the furnace into the bath. 

The cmsts from the Parkes process are then treated to recover the 2inc contained in the dross for reuse in desi1veri2ing This is done by distillation (qv) and more commonly by vacuum technology. A continuous adaptation of the Parkes process is carried out at The Broken Hill Associated Smelters Pty. (Port Pide, AustraUa). The chemistry of this operation is the same as that for batch desi1veri2ing (22,23). 

The principal U.S. lead producers, ASARCO Inc. and The Doe Run Co., account for 75% of domestic mine production and 100% of primary lead production. Both companies employ sintering/blast furnace operations at their smelters and pyrometaHurgical methods in their refineries. Domestic mine production in 1992 accounted for over 90% of the U.S. primary lead production the balance originated from the smelting of imported ores and concentrates. 

Total consumption of lead in the United States in 1993 reached 1,318,800 t. Of this, 766,000 t (58%) is allocated to battery use suppHed as either a mixed oxide or as metal. Approximately 95% of batteries are recycled and the lead recovered. In 1993, 908,000 t of lead came from secondary smelters and refiners compared to 350,000 t originating in primary mines and smelters (39). Approximately 51,000 t of lead was consumed in U.S. production of all oxides and chemicals appHcable to all industries other than batteries. Estimates include 8000 t for plastics, 6000 t for gasoline additives, 2000 t for mbber, and 30,000 t for ceramics, glass, and electronics. Lead is not used to any extent in dispersive appHcations such as coatings. 

Location Reserve base Economic Total reserves Ore-grade fraction, % Mine capacity Refinery and smelter capacity Mine production... 

World Mluminum Mining Refiney, and Smelter Capacity Handbook 1985—1996, AustraHan Mineral Economics, Ltd., Sydney, 1989. 

Copper. Domestic mine production of copper metal in 1994 was over 1,800,000 t. Whereas U.S. copper production increased in the 1980s and 1990s, world supply declined in 1994. There are eight primary and five secondary smelters, nine electrolytic and six fire refiners, and fifteen solvent extraction—electro winning (SX—EW) plants. Almost 540,000 t/yr of old scrap copper and alloy are recycled in the United States accounting for - 24% of total U.S. consumption (11). New scrap accounted for 825,000 t of contained copper. Almost 80% of the new scrap was consumed by brass mills. The ratio of new-to-old scrap is about 60 40% representing 38% of U.S. supply. 

Nickel. Around 56,000 t of nickel were recycled from scrap in 1994. This is just over one-third of the consumption of the metal. The only mining and smelter in the United States was idle in 1994, although INMETCO (EUwood City, Peimsylvania) was a primary consumer of recyclable metal in the production of stainless steel. Almost one-half of all nickel went into the production of stainless steels with an additional 29% in superaHoys and... 

Air. Studies have shown that 2500 years ago lead pollution caused by Greek and Roman silver smelters was a significant problem (4). Based on analysis of lake sediments and Greenland s ice, it was found that lead contamination from smelters in southern and central Europe was carried throughout the northern hemisphere. As long ago as the thirteenth century, air pollution has been linked to the burning of coal (4). The main concern was the smell from the sulfur in the coal and the effects of the soot. It was not until many years later that the effects of air pollution on people s health were discovered. 

Ancient Silver Smelters Polluted the Hemisphere", The Record, Sept. 23, 1994, p. A-23 and P. Brimblecombe, "Attitudes and Responses Towards Air Pollution in Medieval England," H/rPo// Contr. Assoc. (Oct. 1976). 

Hydrometallurgical Processes. Recovery of sulfur in the processing of nonferrous metal sulfides has been in the form of SO2 and/or H2SO4 when smelter (pyrometallurgical) operations are employed. However, there have been accounts of processes, mainly hydrometallurgical, in which sulfur is recovered in the elemental form (see Metallurgy, extractive). 

Sulfuric acid is the most important sulfur-containing intermediate product. More than 85% of the sulfur consumed in the world is either converted to sulfuric acid or produced direcdy as such (see Sulfuric acid and sulfur trioxide). Worldwide, well over half of the sulfuric acid is used in the manufacture of phosphatic fertilizers and ammonium sulfate for fertilizers. The sulfur source may be voluntary elemental, such as from the Frasch process recovered elemental from natural gas or petroleum or sulfur dioxide from smelter operations. 

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