GB455042A - A process for dephosphorising and desulphurising steel - Google Patents

Abstract

In a process for the desulphurization or the simultaneous dephosphorization and desulphurization of steel, the molten steel is intermixed so as to obtain a mutual interpenetration with a very oxidizing fluid slag containing one or more free bases in large excess, the slag being so highly basic and oxidizing and being employed in such quantity that it maintains up to the end of the treatment its strongly basic and oxidizing character. The bases used are alkali or alkaline bases such as soda, potash, lime or baryta. The slags may be melted before use or may be added in the solid state to the steel, their fusion being effected wholly or partly by the heat of the steel itself. The intermixing of the steel and the slag may be produced by pouring the steel with great rapidity on the slag or in the basic converter in which the steel is first blown to reduce the phosphorus content, the slag so produced removed and then blown for a very short period with the strongly basic slag. Other methods of producing the intermixing of the steel and slag as described in U.S.A. Specification 2,015,692 may be used. The vessel in which the intermixing takes place is lined with neutral or basic materials. In an example, a steel containing 0,08 per cent of phosphorus and 0,05 of sulphur was poured into a molten slag containing 20 per cent of iron oxide, 64 of lime, 1 of silica, and 15 of fluorspar, the weight of slag being about 8 per cent of the weight of the steel. British Specification 405,633 also is referred to.