GB197733A - Improvements in and relating to the manufacture of ferrochromium alloys - Google Patents

Abstract

197,733. Wild, R., and Wild, A. H. Feb. 16, 1922. Alloys.-In a process for the production of alloys containing iron and chromium, such as ferro-chrome or unstainable iron or steel of the type in which molten alloy containing oxidizable impurities is subjected to an oxidizing blow, the blow is performed in the presence of an element, such as manganese, which is more readily oxidizable than chromium, for the purpose of reducing the loss of chromium during the blow. In the case of alloys of the' type of unstainable iron or steel, the proportion of manganese is not less than about 2 per cent, or not less than about two-thirds of the oxidizable impurities; in the case of ferro-chrome, the proportion of manganese may be lower. The manganese may be introduced during the manufacture of the crude alloy by effecting the reduction in the presence of manganese or of a reducible compound thereof, or by using silico-manganese as the reducing-agent; or the manganese may be added, for example as ferro-manganese, to the already prepared alloy. The reduction of the chromium compound may be effected in a molten bath of carbon-free or low-carbon iron or steel, or ferro-chrome may be added to the molten iron or steel, the product in either case being blown under the above-described conditions; or ferro-chrome blown under these conditions may be added to iron or steel. The reduction-mixture may be used in the form of briquettes. The blast may be delivered to the metal through a wrought-iron pipe covered with fire-clay and it may carry in reagents such as chromite, or lime.