Process for the manufacture of unalloyed and alloyed steels having the low content of phosphorus and sulphur customary in special steels

摘要

Iron of high phosphorus content is prerefined by treatment with the iron-rich slag resulting from the first stage of blowing, e.g. by pouring into the slag contained in a ladle, whereby the iron content of the slag is reduced to below 15%. The iron is then transferred to a converter containing the slag of iron content greater than 15% from the second stage of blowing, where it is blown with oxygen, slag formers being added, until the phosphorus content is below 0.15%, the carbon content being greater than 1.3%. The slag is then removed, for use in the pre-refining stage, a new slag rich in iron formed, and the bath again blown until the desired carbon content is obtained. Ore scrap, iron nodules or sponge, or appropriate iron alloys may be used as coolants.