Development of Slag Minimum Refining Process by Desiliconization of Hot Metal

New process "SMP" (Slag Minimum Refining Process) which consists of hot metal desiliconization stage in hot metal containner and dephospharization and decarbarization stage in LD converter has been studied in order to reduce the consumption of refining fluxes and slag volume yield in conventional LD process. After experimental studies which have been carried out in KR equipment and conventional LD converter to estimate the feasibility of this new process, it was cleared that hot metal desiliconization treatment can be done with simple equipment by using proper desiliconization agent and flux and its proper adding method. By this new process, CaO consumption for dephosphorization in LD converter and slag volume can be reduced drastically with decreasing Si content in hot metal and that CaO consumption and slag volume required is 18 kg/t.s, 42 kg/t.s at Si=0.15% by low carbon rimmed steel. As a result of it, linning life of refractory can be extended and the amount of metal and heat loss can be decreased and it makes the LD refining very stable. Based on the results obtained by the above experiments, a practical equipment of hot metal desiliconization treatment has been installed and came in use in October 1979. and now is in a stable operation.