GB522561A - Improvements in or relating to materials for use in the production of chromium and alloys containing chromium - Google Patents

Abstract

522,561. Alloys ; chromium. UDY, M. J. Sept. 15, 1938, Nos. 5191, 5192, 5193, and 5194. Convention dates, Sept. 23, 1937, Jan. 22, 1938, July 23, 1938, and Sept. 7, 1938. Divided out of 520,331. [Class 82 (i)] A reaction mixture for use in the production of chromium or chromium alloys comprises an intimate mixture of calcium chromite and calcium chromate with a non-carbonaceous reducing-agent such as silicon aluminium, or magnesium, or alloys such' as ferrochromesilicon, or silicides such as calcium, magnesium, or aluminium silicides, including nickel silicide in the case where the final alloy is to contain nickel. High-carbon ferrochromium may be roasted with lime, with or without soda to obtain the chromite and chromate mixture ; or the roasting may be effected in two stages, lime and soda being added in the second stage only: Other oxidizing agents such as sodium chlorate, nitrate, or bichromate, manganese-dioxide, or chromium trioxide may be present. The chromium-iron ratio of the oxidized product may be improved, 11, desired, by the process described in Specification 437,008 to the point, if necessary, of the total exclusion of iron. The product is ground and mixed with the reducing-agent in finely-divided form, or the two materials are ground together, and the mixture may be employed in briquetted or loose form or in bags or metal containers for the direct production of iron-alloys, or may be added to a steel bath, with the intervention if necessary of an overlying slag ; or, if the iron has been selectively reduced and removed, chromium may be obtained. Specification 520,331 also is referred to.