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(also ferrochrome), a ferroalloy containing approximately 70 percent Cr (Fe and impurities constituting the remainder). Chromium ores (52–58 percent Cr2O3) serve as the raw material in the production of ferrochromium.
High-carbon ferrochromium (6–8 percent C) is produced in ore-reducing furnaces, while the alloy’s refined grades, a category including medium-carbon (0.8–1.5 percent C), low-carbon (0.1–0.5 percent C), and carbon-free (0.01–0.06 percent C) ferrochromium, are produced in electric refining furnaces by the silicothermic method. Medium-carbon ferrochromium is also produced in special converters from the high-carbon grade, and carbon-free ferrochromium is also produced by mixing chromium-calcium and silicon-chromium melts in a ladle. Carbon-free ferrochromium is obtained in briquette form by the decarbonization of briquetted powders of the medium-carbon and high-carbon grades of ferrochromium in a vacuum furnace at 1380°C; if at the end of this process the furnace is filled with nitrogen, nitrided ferrochromium (approximately 6 percent N) is obtained. Ferrochromium is used for alloying steel, and foundry ferrochromium serves as an intermediate in the production of ferrochrome silicon.