PROCESS FOR DECARBURIZING HIGH-Cr MOLTEN PIG IRON.

摘要

Molten stainless steel is mfd. by continuously subjecting Cr materials such as Cr ores or Cr pellets to melt reduction and decarbonisation in one vessel at high treating speeds. Process comprises melt redn. blowing an inert gas through a bottom-blown tuyere to form projections on the molten metal surface and blowing an inert gas against the projections through a side-blown tuyere to diffuse the molten metal into a Cr material-floating zone in the slag to accelerate the reduction of the Cr material with C contained in the molten metal. Alternatively blowing O2 for decarbonisation into the molten metal through a top-blown lance and O2 for secondary combustion into the slag to form a secondary combustion zone mainly in the slag, and vigorously stirring the slag by the side-blown gas gives heat produced by the secondary combustion to the Cr ores with high efficiency while keeping a second combustion ratio at 0.3 or more to assure high secondary combustion. After the melt reduction, discharging the slag and top-blowing O2 for decarbonisation diluted with an inert gas and blowing an inert gas through the bottom-blown tuyere stirs the molten metal vigorously.