Chromite reserve

Russia and the RepubHc of South Africa account for more than half the world s chromite ore production. Almost all of the world s known reserves of chromium are located in the southeastern region of the continent of Africa. South Africa has 84% and Zimbabwe 11% of these reserves. The United States is completely dependent on imports for all of its chromium (4). The chromite s constitution varies with the source of the ore, and this variance can be important to processing. Typical ores are from 20 to 26 wt % Cr, from 10 to 25 wt % Fe, from 5 to 15 wt % Mg, from 2 to 10 wt % Al, and between 0.5 and 5 wt % Si Other elements that may be present are Mn, Ca, Ti, Ni, and V. AH of these elements are normally reported as oxides iron is present as both Fe(II) andFe(III) (5,6). 

Chromium, 122 ppm of the earth s crustal rocks, is comparable in abundance with vanadium (136 ppm) and chlorine (126 ppm), but molybdenum and tungsten (both 1.2 ppm) are much rarer (cf. Ho 1.4 ppm, Tb 1.2 ppm), and the concentration in their ores is low. The only ore of chromium of any commercial importance is chromite, FeCr204, which is produced principally in southern Africa (where 96% of the known reserves are located), the former Soviet Union and the Philippines. Other less plentiful sources are crocoite, PbCr04, and chrome ochre, Cr203, while the gemstones emerald and ruby owe their colours to traces of chromium (pp. 107, 242). 

Most of the world s chromium reserves occur in large, layered mafic/ultramafic intrusions such as the 2.06 Gyr old Bushveld Complex in the Republic of South Africa, where nearly mono-mineralic layers of chromite appear to result from the mixing of primitive and evolved liquids that... 

The certain reserves of chromite were estimated in 1975 to be 2.8 10 t, the probable reserves to be 5.4 10 t. Of the certain reserves 74% are in South Africa and 20% in Zimbabwe. In South Africa the reserves are so large that the mining companies have not bothered to determine them accurately. Exhau.stion of the reserves in the near future is not to be expected. Important extracting countries outside Southern Africa are (in alphabetical order) Albania, Brazil, Finland, the former States of the USSR, India, Iran, Madagascar, the Philippines and Turkey. Table 3.3-2 gives the chromite extraction figures for 1992. 

About 75% of the world s reserve base of chromium ore lies in South Africa, and the bar chart illustrates the dominance of South Africa in world chromite output. 

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