Zinc-lead smelting

Production. Indium is recovered from fumes, dusts, slags, residues, and alloys from zinc or lead—zinc smelting. The source material itself, a reduction bullion, flue dust, or electrolytic slime intermediate, is leached with sulfuric or hydrochloric acid, the solutions are concentrated, if necessary, and cmde indium is recovered as 99+% metal. This impure indium is then refined to 99.99%, 99.999%, 99.9999%, or higher grades by a variety of classical chemical and electrochemical processes. 

Indium may be recovered from zinc ores by several patented processes. Usually it is recovered from residues obtained from zinc extraction. The residues, slags, fume, or dusts from zinc smelting or lead-zinc smelting are treated with a mineral acid. Other steps involved in recovery often vary, but mostly use solvent extraction and precipitation steps. In some processes, treatment with caustic soda yields indium hydroxide. The hydroxide is calcined to obtain oxide, which then is reduced with hydrogen at elevated temperatures to obtain the metal. Distillation or electrolysis are the final steps to... 

Naturally occurring cadmium compounds are limited to the rare minerals, greenockite [1317-58-4], CdS, and otavite (1), an oxycarbonate, but neither is an economically important source of cadmium metal or its compounds. Instead, cadmium compounds are more usually derived from metallic cadmium [7440-43-9] which is produced as a by-product of lead—zinc smelting or electrolysis (see Cadmium AND CADMIUM alloys). Typically, this cadmium metal is burnt as a vapor, to produce the brown-black cadmium oxide [1306-19-0], CdO, which then acts as a convenient starting material for most of the economically important compounds. 

Filzek PDB, Spurgeon DJ, Broil G, Svendsen C, Hankard PK, Kammenga JE, Donker MF1, Weeks JM. 2004. Pedological characterisation of sites along a transect from a primary cadmium/lead/zinc smelting works. Ecotoxicology 13 725-737. 

Source of SO2 M0S2 roasting and S burning Lead zinc smelting/roasting... 

The abundance of indium in the earth s cmst is probably about 0.1 ppm, similat to that of silver. It is found in trace amounts in many minerals, particulady in the sulfide ores of zinc and to a lesser extent in association with sulfides of copper, tin, and lead. Indium follows zinc through flotation concentration, and commercial recovery of the metal is achieved by treating residues, flue dusts, slags, and metallic intermediates in zinc smelting and associated lead (qv) and copper (qv) smelting (see Metallurgy, EXTRACTIVE Zinc and zinc alloys). 

In addition to domestic production of Frasch and recovered elemental sulfur, U.S. requirements for sulfur are met with by-product sulfuric acid from copper, lead, molybdenum, and zinc smelting operations as well as imports from Canada and Mexico. By-product sulfur is also recovered as sulfur dioxide and hydrogen sulfide (see Sulfurremoval and recovery). 

In the recovery of cadmium from fumes evolved in the Imperial Smelting process for the treatment of lead—zinc concentrates, cadmium is separated from arsenic using a cation-exchange resin such as Zeocarb 225 or Ambedite 120 (14,15). Cadmium is absorbed on the resin and eluted with a brine solution. The cadmium may then be recovered direcdy by galvanic precipitation. 

Zinc-lead slags Smelting of zinc and lead Stockpiled and used locally Bulk fill and some in pavement asphalt... 

In the most common hydrometallurgical process for zinc manufacturing, the ore is leached with sulfuric acid to extract the lead/zinc. These processes can operate at atmospheric pressure or as pressure leach circuits. Lead/zinc is recovered from solution by electrowinning, a process similar to electrolytic refining. The process most commonly used for low-grade deposits is heap leaching. Imperial smelting is also used for zinc ores. 

Plants readily accumulate lead from soils of low pH or low organic content however, uptake is significantly reduced after the application of lime or phosphate, which converts lead to hydroxides, carbonates, or phosphates of relatively low solubility (Demayo et al. 1982). Lead persists for lengthy periods in forest litter the estimated Tb 1/2 is 220 years (Turner et al. 1985). High levels of lead persisted for at least 6 years in litter, soil, amphibians, and mammals after zinc smelting was discontinued in Palmerton, Pennsylvania (Storm et al. 1994). Lead seems to be tightly bound by... 

ISP (Imperial Smelting Process)—a combined lead-zinc process in which oxidized concentrates are reduced with coke in a shaft furnace and the zinc vapor collected in a lead splash condenser. 

Thallium is manufactured commercially as a by-product from the roasting of pyrite ores, from sulfuric acid plants, and from the smelting of lead, zinc, and copper. The global... 

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