GB937507A - Process for the production of iron-chromium alloys - Google Patents

Abstract

Iron chromium alloys of controlled carbon content are obtained from ores of chromium oxide and iron oxide by a duplex process in which a part of the ore is completely reduced, preferably in an arc furnace, with carbonaceous reducing agent to yield a high carbon ferrochromium, while a further part is separately reduced using a restricted amount of carbonaceous reducing agent to produce low-carbon metallic iron and a chromium-bearing slag which is returned to the ferrochromium smelting stage. The ferrochromium and metallic iron are then mixed and refined, with the addition of other alloying constituents e.g. nickel if desired, to yield the required alloy. Prior to smelting the ore is calcined, e.g. in a rotary kiln, during which process partial reduction may be carried out; addition of fluxing components so that preferably the slags lie within the range 1.0-2.25 parts by weight of base (calculated as MgO and excluding iron oxide) to 1 part of silica is carried out either before or after calcining. In a modification of the process each smelting step may be preceded by its own calcining step the raw material for ferrochromium production being a chromium containing ore and that for the metallic iron production being an iron ore. In a further modification additional elements such as nickel may be added as oxide ores at the reduction stage. Any surplus metallic iron may be withdrawn from the process and used in the production of carbon steel. Specification 911,992 is referred to.