Deposits of ore

Deposits of ores containing palladium, as well as other metals, are found in Siberia and the Ural Mountains of Russia, Canada, and South Africa, as well as in South America. 

Metal complexation (and fixation) in soils and sedimentary basins Deposition of ore metals (reducing agents)... 

The majority of the ore tonnage treated by hydrometallurgical means is processed at atmospheric pressure because of the obvious economic advantage. In the case of the secondary recovery of additional copper values from mine waste dumps, mined-out ore bodies, and marginal deposits of ores with complex mineralization, the only economic process has to be at ambient pressure. 

The annual production of metals normally present at trace levels in the biosphere which are in common use in our society is given in Table 1. These quantities are a measure of the rates at which localized deposits of ores of these metals are being mobilized and made available for dispersal. The annual world production of aluminium is substantially higher (13.7 million tonnes in 1974) than for any of the elements in the Table, while the production of iron is of a higher order of magnitude (equivalent to 710 million tonnes of steel in 1974). 

The element is found in niobite (or columbite), niobite-tantalite, parochlore, and euxenite. Large deposits of niobium have been found associated with carbonatites (carbon-silicate rocks), as a constituent of parochlore. Extensive ore reserves are found in Canada, Brazil, Nigeria, Zaire, and in Russia. 

A member of the platinum group, ruthenium occurs native with other members of the group in ores found in the Ural mountains and in North and South America. It is also found along with other platinum metals in small but commercial quantities in pentlandite of the Sudbury, Ontario, nickel-mining region, and in pyroxinite deposits of South Africa. 

Discovered in 1803 by Wollaston, Palladium is found with platinum and other metals of the platinum group in placer deposits of Russia, South America, North America, Ethiopia, and Australia. It is also found associated with the nickel-copper deposits of South Africa and Ontario. Palladium s separation from the platinum metals depends upon the type of ore in which it is found. 

The ores of most importance are fluorspar, CaF2 fluorapatite, Ca (P0 2Fj cryoHte [15096-52-3], Na AlF. Fluorspar is the primary commercial source of fluoiine. Twenty-six percent of the world s high quaHty deposits of fluorspar are ia North America. Most of that is ia Mexico. United States production ia 1987—1991 was 314,500 metric tons, most of which occurred ia the Illinois-Kentucky area. Imported fluorspar ia 1990—1991 represented about 82% of U.S. consumption 31% of U.S. fluorspar imports were from Mexico and 29% from China compared to 66% from Mexico ia the 1973—1978 period. The majority of the fluorine ia the earth s cmst is ia phosphate rock ia the form of fluorapatite which has an average fluorine concentration of 3.5%. Recovery of these fluorine values as by-product fluorosiHcic acid from phosphate production has grown steadily, partially because of environmental requirements (see Phosphoric acid and THE phosphates). 

In the United States, the first ironworks was built at Jamestown, Virginia, in 1619. The Hammersmith furnace in Saugus, Massachusetts, built in 1645, operated until 1675. This early American ironworks has been restored and is called the Saugus Iron Works. Iron blast furnaces appeared in many locahties where there were deposits of iron ore. Small bodies of iron ore in New Jersey, Connecticut, Massachusetts, Pennsylvania, and New York formed the basis of many small colonial furnaces. 

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. 

Unconformity-Related Deposits. Deposits of the unconformity-related type occur spatially close to significant unconformities. These deposits usually developed during the period about 1800—800 million years ago in intracratonic basins. Deposits also developed during Phanerozoic time. Examples of unconformity-related deposits include the ore bodies at Cluff Lake, Key Lake, and Rabbit Lake in northern Saskatchewan, Canada, and those in the Alligator Rivers area in northern AustraHa (12). 

Vein Deposits. The vein deposits of uranium are those in which uranium minerals fill cavities such as cracks, fissures, pore spaces, breccias, and stockworks. The dimensions of the openings have a wide range, from the narrow pitchblende-fiHed cracks, faults, and fissures in some of the ore bodies in Europe, Canada, and AustraHa to the massive veins of pitchblende at Jachymov, Czech RepubHc (15). 

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