As is wrotten about ferrochromium in Encyclopedia Brittanica, alloy of chromium with 30 to 50 percent iron, used to incorporate chromium into steel.
It is produced in an electric furnace using chromium ore, iron or iron ore, and carbon, usually anthracite coal. In the intense heat the carbon reduces the metal oxides to the molten alloy, which is poured out into slabs. Chromium is added to iron and nickel in the form of ferrochromium (about 70 percent chromium) to produce alloys specially characterized by their high resistance to corrosion and oxidation. Used in small amounts, ferrochromium hardens steel. Stainless steels are alloys of chromium and iron in which the chromium content varies from 10 to 26 percent. Ferrochromium and other chromium alloys are used to fabricate many products. Most ores smelted with coke in an electric furnace produce metals that are saturated with carbon. For ferrochromium, the saturation point is approximately 9 percent, but actual carbon content varies with the condition of the ore and the composition of the slag. For example, ferrochromium used to be use with a lumpy, refractory ore and a slag containing approximately equal amounts of magnesia, alumina, silica. During ferrochromium production, boron oxide B2 O3 is added to the charge when melting the ferrochromium in the electric furnace.This boron oxide will be added in the form of dried chemical discards resulting from the production of boric acid and/or borax, the said discards containing 2% to 7% of boron oxide.