LEAD-ZINC

Prior to about 1920, flotation procedures were rather crude and rested primarily on the observation that copper and lead-zinc ore pulps (crushed ore mixed with water) could be benefacted (improved in mineral content) by treatment with large amounts of fatty and oily materials. The mineral particles collected in the oily layer and thus could be separated from the gangue and the water. Since then, oil flotation has been largely replaced by froth or foam flotation. Here, only minor amounts of oil or surfactant are used and a froth is formed by agitating or bubbling air through the suspension. The oily froth or foam is concentrated in mineral particles and can be skimmed off as shown schematically in Fig. XIII-4. 

Silver occurs native and in ores such as argentite (Ag2S) and horn silver (AgCl) lead, lead-zinc, copper, gold, and copper-nickel ores are principal sources. Mexico, Canada, Peru, and the U.S. are the principal silver producers in the western hemisphere. 

Leaded tin bronze Leaded tin bronzes Leaded yellow brass Leaded zinc oxide Lead 2-ethylhexanoate... 

Flotation or froth flotation is a physicochemical property-based separation process. It is widely utilised in the area of mineral processing also known as ore dressing and mineral beneftciation for mineral concentration. In addition to the mining and metallurgical industries, flotation also finds appHcations in sewage treatment, water purification, bitumen recovery from tar sands, and coal desulfurization. Nearly one biUion tons of ore are treated by this process aimuaHy in the world. Phosphate rock, precious metals, lead, zinc, copper, molybdenum, and tin-containing ores as well as coal are treated routinely by this process some flotation plants treat 200,000 tons of ore per day (see Mineral recovery and processing). Various aspects of flotation theory and practice have been treated in books and reviews (1 9). 

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. 

Activators promote the reaction of the coUector with some minerals. For example, ordinarily xanthates do not bind to sphalerite, but pretreatment of the sphalerite using copper sulfate enables it to adsorb the xanthate. Thus it is possible to float the sphalerite from lead—zinc ores after the galena has been recovered. 

Mnnual bulletin. International Lead Zinc Study Group, London, 1993. 

D. Greninger, V. KoUonitsch, and C. H. Kline, Eead Chemicals International Lead Zinc Research Organization, Inc., New York, 1975, p. 173. 

E. C. Porter, Zinc Handbook Properties, Processing, and Use in Design, International Lead Zinc Research Organization, Marcel Dekker, New York, 1991. 

Lead—Zinc 90 Proceedings of a World Symposium on Metallurgy and Environmental Control," 119th TMS Annual Meeting Feb, 18—21, 1990, Warrington, Pa., TMS Lead, Zinc, and Tin Committee. 

Metal Copper Nickel Lead Zinc Silver... 

Ust-Kamenogorsky Lead—Zinc Plant, East Ka2akhstan, Russia... 

Catalytic Oxidation. Catalytic oxidation is used only for gaseous streams because combustion reactions take place on the surface of the catalyst which otherwise would be covered by soHd material. Common catalysts are palladium [7440-05-3] and platinum [7440-06-4]. Because of the catalytic boost, operating temperatures and residence times are much lower which reduce operating costs. Catalysts in any treatment system are susceptible to poisoning (masking of or interference with the active sites). Catalysts can be poisoned or deactivated by sulfur, bismuth [7440-69-9] phosphoms [7723-14-0] arsenic, antimony, mercury, lead, zinc, tin [7440-31-5] or halogens (notably chlorine) platinum catalysts can tolerate sulfur compounds, but can be poisoned by chlorine. 

Zinc minerals tend to be associated with those of other metals the most common ate zinc—lead or lead—zinc, depending upon the dominant metal, zinc— copper or copper—zinc, and base metal such as silver. Zinc does occur alone, most often in the northeastern district, and here, as elsewhere, recoverable amounts of cadmium (up to 0.5%) are present. Other minor metals recovered from zinc ores are indium, germanium, and thallium. 

Leaded Zinc Oxide. Oxides containing more than 5 wt % basic lead sulfate are classified as leaded and are made ia the American process from high lead materials, usually lead sulfide mineral, or by blending ziac oxide and basic lead sulfate. There is only one manufacturer ia the United States and the product contains 20—28 wt % basic lead sulfate. Leaded oxides are used only ia mbber ia the United States. 

H. E. Brown, Zinc Oxide, Properties and Applications, International Lead Zinc Organization, Inc., New York, 1976, pp. 56—59. 

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. 

M. Eamsworth, Cadmium Chemicals, International Lead Zinc Research Org., New York, 1980. 

R. A. Eppler and D. S. Carr, in Proceedings of the 3rd International Cadmium Conference, International, Lead Zinc Research Organization, New York, 1982,... 

Magmont Iron, Mo. Cominco American Incorporated lead—zinc ore, concentrated ... 

Includes copper-lead ore, gold ore, gold—sHver ore, lead—zinc ore, molybdenum ore, tungsten ore, zinc ore, fluorspar, flux ores, cleanup, ore shipped direcdy to smelters, and tailings. 

A U.S. Bureau of Mines survey covering 202 froth flotation plants in the United States showed that 198 million tons of material were treated by flotation in 1960 to recover 20 million tons of concentrates which contained approximately 1 billion in recoverable products. Most of the worlds copper, lead, zinc, molybdenum, and nickel are produced from ores that are concentrated first by flotation. In addition, flotation is commonly used for the recoveiy of fine coal and for the concentration of a wide range of mineral commodities including fluorspar, barite, glass sand, iron oxide, pyrite, manganese ore, clay, feldspar, mica, sponumene, bastnaesite, calcite, garnet, kyanite, and talc. 

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