Ore processing

Osmium occurs in iridosule and in platinum-bearing river sands of the Urals, North America, and South America. It is also found in the nickel-bearing ores of Sudbury, Ontario region along with other platinum metals. While the quantity of platinum metals in these ores is very small, the large tonnages of nickel ores processed make commercial recovery possible. 

A similar reaction occurs when polyacrylamide is mixed with glyoxilic acid [298-12-4], C2H2O2, at pH about 8. This reaction produces a polymer with the CONHCH(OH)COOH fiinctionahty, which has found appHcation in phosphate ore processing (53). 

The concentration of most metals in the earth s cmst is very low, and even for abundant elements such as aluminum and iron, extraction from common rock is not economically feasible. An ore is a metallic deposit from which the metal can be economically extracted. The amount of valuable metal in the ore is the tenor, or ore grade, usually given as the wt % of metal or oxide. Eor precious metals, the tenor is given in grams per metric ton or troy ounces per avoirdupois short ton (2000 pounds). The tenor and the type of metallic compounds are the main characteristics of an ore. The economic feasibihty of ore processing, however, depends also on the nature, location, and size of the deposit the availabihty and cost of a suitable extraction process and the market price of the metal. 

Mill Tailings. Recovery efficiency in ore processing is not 100%. Accumulated mill tailings contain tens of thousands of metric tons of uranium. Whereas improved techniques have been employed to recover some of this uranium, the recovery rate is still generally low, approximately 35—50%, owing to metallurgical problems and economic considerations (33). 

J. W. Clegg and D. D. Foley, Uranium Ore Processing Addison-Wesley Pubhshing Co., Reading, Mass., 1958. 

Ore Processing. Vanadium is recovered domestically as a principal mine product, as a coproduct or by-product from uranium—vanadium ores, and from ferrophosphoms as a by-product in the production of elemental phosphoms. In Canada, it is recovered from cmde-oil residues and in the Repubhc of South Africa as a by-product of titaniferous magnetite. Whatever the source, however, the first stage in ore processing is the production of an oxide concentrate. 

J. B. Rosenbaum, Vanadium Ore Processing, Meeting of High Temperature Metal Committee, preprint A71-52, AIME, New York, 1971,14 pp. 

Eor example, beryUium occurs at the bottom of a displacement series with NTA allowing this metal to be recovered as the hydroxide by pH adjustment of an ore processing solution all of the interfering metals remain sequestered by chelation (14). Additionally, because other metals present caimot displace iron in an iron—EHPG chelate, the chelate can be used in highly calcareous soils to supply iron as a trace nutrient in agriculture (15). 

Various techniques are available to separate the different types of particles that may be present in a sohd mixture. The choice depends on the physicochemical nature of the sohds and on site-specific considerations (for example, wet versus diy methods). A key consideration is the extent of the liberation of the individual particles to be separated. Particles attached to each other obviously cannot be separated by direct mechanical means except after the attachment has been broken. In ore processing, the mineral values are generally liberated by size reduction (see Sec. 20). Rarely is liberation complete at any one size, and a physical-separation flow sheet wih incorporate a sequence of operations that often are designed first to rejec t as much... 

A flow sheet for one iron ore process is shown in Fig. 20-56. For the grinding of softer copper ore the rod mill might be eliminated, both coarse-crushing and baU-milhng ranges being extended to fill the gap. 

Sulfur Dioxide, Spray Towers Flue gases and offgases from sulfuric acid plants contain less than 0.5 percent SO9 smelter gases like those from ore processing plants may contain 8 percent. The high-concentration streams are suitable for the manufacture of sulfuric acid. The low concentrations usually are regarded as contaminants to be destroyed or recovered as elemental siilfur by, for example, the Claus process. 

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