The metallurgical characteristics and reaction mechanism of hot metal desiliconization by using gaseous oxygen as a desiliconizing agent, which is injected into hot metal through submerged lance, are investigated and following results are obtained:
1) Desiliconizing reaction is controlled by the rate of oxygen supply until Si content reaches 0.10%, and efficiency of oxygen used for desiliconization is as high as 50-60%. Demanganization reaction is suppressed by the promotion of reduction of MnO with Fe during the floating process from fire spot up to surface. Decarburization reaction is also suppressed with the effect of ferrostatic pressure at fire spot with increasing the depth of submerged lance.
2) Hot metal temperature after treatment increases in proportion to the amount of desiliconization and thermal flexibility of total process increases extensively.
3) The reaction by gaseous oxygen injection starts from the formation of Fe-oxide at fire spot and succeeds to the oxidation of Si, Mn and C by Fe-oxide. But MnO is reduced by Fe during floating process.
4) Hot metal desiliconization technology by gaseous oxygen injection is applied to the stainless steel production process. The production of stainless steel with very low P content and the reduction of production cost of stainless steel are attained by this application.