GB831251A - Improvements relating to processes for refining phosphorus-containing pig iron - Google Patents

Abstract

831,251. Refining iron. PHOENIXRHEINROHR AKTIENGESELLSCHAFT VEREINIGTE HUTTON-UND ROHRENWERKE. Sept. 10, 1957 [March 12, 1957], No. 28543/57. Class 72 A process for refining phosphorus-containing pig iron in a basic line converter, is characterized in that a charge of pig iron with added lime is bottom blown in a first stage with the converter in an upright position until part of its carbon content is burnt and a slag prepared, the converter being then rotated until the metal and slag are clear of the tuyeres and, in a second stage, oxygen blown on to the surface of the charge until the phosphorus content is reduced to less than 0.1%, the converter being then turned back to the upright position in which, in a third stage, the charge is bottom blown until the desired carbon content is reached. After the third stage, the slag may be changed and this followed by further stages of blowing on to the surface in the tilted position and from the bottom in the vertical position. In an example, pig iron with 3.6% carbon and 1.75% phosphorus with the usual contents of manganese, silicon and sulphur was blown with oxygen enriched air according to the first stage of the invention until the carbon content reached 0.7% after 7¢ minutes. Blowing for 15 minutes with an oxygen lance in the second stage reduced the phosphorus content from 1.4% to 0.07% while the carbon content was reduced to 0.3%. In the third stage the charge was bottom blown for ¢ minute and the carbon content reduced to 0.15% and phosphorus to 0.04%. After forming a new slag and blowing again in the tilted position the carbon content was reduced to 0.1% and the phosphorus content to 0.02%.