GB492740A - Improvements in and relating to the dephosphorising and/or desulphurising of steel - Google Patents

Abstract

In the manufacture of steel by Bessemer process, the silicon content of the steel is increased sufficiently to furnish extra heat by oxidation of the additional silicon, the blow commenced and in the case of a basic converter under a slag which removes a portion of the phosphorus in the metal, the blow stopped when there is still more phosphorus left than is required in the final steel, the slag poured and prior to a second short blow dephosphorizing and/or desulphurizing materials added, these materials being melted by the extra heat to form a second slag. In the basic process the metal to be treated contains not less than 0,5 per cent of silicon, preferably between 0,5-1,0, and less than 0,7 of manganese, and the first blow is stopped when the phosphorous content is above 0,08 per cent. The steel may be desulphurized with soda before treatment in the converter. In an example, the first slag is produced by an addition of lime, and the second by the addition of a mixture of lime, fluorspar, mill scale and a small amount of gravel. Specifications 19053/04, [Class 72], and 474,224 are referred to.