There are three main types of chromite in nature: high-chromium chromite, high-iron chromite and high-aluminum chromite used as refractory minerals. The application of chromite products is more interchangeable than in the past with improved processing technologies. At one time only raw “lump” chromite was used in smelters to produce ferrochrome for stainless steel production. With the reduction of lump chromite quality, fine grained chromite is being processed (agglomerated and pelletized, or directly reduced in plasma arc furnaces) to produce higher quality ferrochrome.
The production of stainless steel and similar specialty steel products is not possible without the use of the mineral chromite, the world’s principal source of chromium metal. The world chromite market consumes approximately 22 million tonnes of chromite per year (2016), 90% of which is consumed as ferrochrome dedicated to stainless steel production. By 2017 world chromite consumption is expected to increase to about 22.3 million tonnes per annum, following the recent global recession. Since 2000 chromite consumption has grown at a rate of about 5.4% per year until 2007. This growth was driven principally by Chinese consumption, accounting for almost one-third of world demand. The production of ferro-chrome requires about 2.4-2.5 tonnes of chromite per tonne of ferrochrome, and the production of standard grade stainless steel requires about 0.66 tonnes of chromite per tonne of stainless steel.
Minor chromite production/consumption is dedicated to the refractory and foundry chromite markets (4%) and the chemical chromium business (2-3%). The demand for refractory grade chromite has continued to decrease since 1970 with the introduction of new smelting methods and the health concern over hexavalent chromium. Foundry grade chromite consumption has steadily increased with its replacement of radioactive zircon and the demand for high quality metal castings. The use of chemical grade chromium continues to grow steadily with its use in leather tanning and electroplating. World consumption of these three chromite products totals less than 1.2 million tonnes per year.
World consumption of foundry grade chromite (FGR) totaled about 600,000 tonnes in 2016, most of which was sourced from South Africa. Chromite is preferred over silica sand and other foundry products due to the quality of castings and its non-radioactive composition. Besides stringent chemical compositional character, the size, shape and acid consumption rate are critical for this type of premium chromite product. Typically foundry grade sand must have a chemical composition exceeding 44% chromium oxide, no more than 27% iron and less than 4% silica. Ninety percent of the chromite sand must range from 0.39 to 0.70 millimeters in size. The product must have low magnesium and aluminum contents and an AFS number (American Foundrymen Society) average grain size distribution number not less than AFS-GFN # 51. Typically, less than 60% of chromite mined and processed is recovered as foundry grade chromite (67% of spiral product). The cost of producing foundry grade chromite is considerably greater than the cost of producing sintered metallurgical grade chromite. High quality chromite foundry sand is replacing/substituting for zircon (priced ~ $1,000/tonne). Some of the New Caledonia chromite deposits appear to meet foundry grade chromite specifications at the early prospect stage.