GB244413A - Method of making iron chromium alloys - Google Patents

Abstract

244,413. Penniman, W. B. B., and Shackelford, E. J. Dec. 11, 1924. [Convention date]. No Patent granted (Sealing fee not paid). Alloys.-A process for making low-carbon ironchromium alloys, which may be stainless iron or steel or ferro-chromium, comprises successively charging and reducing quantities of chromium ore in contact with a reception slag over a molten iron or steel bath, removing the slag, and supplying fresh slag material between the successive charges of ore mixture, decarburizing the molten alloy by means of an oxidizing slag, and finally deoxidizing the product. The temperature of the furnace is preferably varied with successive charges of ore mixture. A molten iron bath in a furnace, which is preferably electric, is covered with a reception slag of lime and fluorspar. A finely crushed mixture, free from dust, of ore, flux, and reducing agent which may be coke, petroleum coke, or anthracite, is fed to the surface of the bath, the slag which forms being removed when preferably about half the mixture has been added and reduced ; the remainder of the charge is then added and reduced and the slag removed as before.. After removal of the last smelting slag, a slag of lime and fluorspar is added and melted, whereupon chromium ore is added and the heating continued until the carbon content is sufficiently reduced. Deoxidizing material, which may be ferrosilicon or other alloy, is then added to the surface of the decarburizing slag, and when the desired result is attained the slag is removed and the metal is covered with powdered lime, after which it is tapped and cast. The Specification as open to inspection under Sect. 91 (3) (a) states also that ferrochromium made by other processes may be decarburized by the steps referred to above. This subject-matter does not appear in the Specification as accepted.