Silver smelting

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). 

Many nonferrous metals can be extracted by reduction smelting, eg, copper, tin, nickel, cobalt, silver, antimony, and bismuth. Blast furnaces are sometimes used for the smelting of copper or tin, but flash and reverberatory furnaces are more common for metals other than lead. 

The washed slime is dried and melted to produce slag and metal. The slag is usually purified by selective reduction and smelted to produce antimonial lead. The metal is treated ia the molten state by selective oxidation for the removal of arsenic, antimony, and some of the lead. It is then transferred to a cupel furnace, where the oxidation is continued until only the silver—gold alloy (dorn) remains. The bismuth-rich cupel slags are cmshed, mixed with a small amount of sulfur, and reduced with carbon to a copper matte and impure bismuth metal the latter is transferred to the bismuth refining plant. 

The thermodynamics of copper smelting are discussed ia References 17 and 18. Silver and gold are quantitatively recovered with the copper throughout the smelting operations rather than being lost with the slag. 

Reich-schaum, m. (Metal.) the zinc crust, rich in silver, etc., formed in the Parkes process, -schlacke, /. rich slag, -schmelzen, n. smelting of precious metals. 

Cadmium (Cd) anode cells are at present manufactured based on nickel-cadmium, silver-cadmium, and mercury-cadmium couples. Thus wastewater streams from cadmium-based battery industries carry toxic metals cadmium, nickel, silver, and mercury, of which Cd is regarded the most hazardous. It is estimated that globally, manufacturing activities add about 3-10 times more Cd to the atmosphere than from natural resources such as forest fire and volcanic emissions. As a matter of fact, some studies have shown that NiCd batteries contribute almost 80% of cadmium to the environment,4,23 while the atmosphere is contaminated when cadmium is smelted and released as vapor into the atmosphere4 Consequently, terrestrial, aquatic, and atmospheric environments become contaminated with cadmium and remain reservoirs for human cadmium poisoning. 

Smelting and refining of gold, silver, copper, zinc, uranium, and lead ores... 

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