METHOD FOR PRETREATMENT OF MOLTEN IRON AND METHOD FOR REFINING

摘要

The present invention provides a pretreatment method and a refining method of molten iron, the methods allowing the refining to not use fluorite in both the processes of molten iron pretreatment and decarburization, minimizing the formation of slag for dephosphorization in the decarburization process, and increasing heat margin by adding a carbon source to the molten iron with great efficiency. The present invention is, in a molten iron pretreatment method wherein molten iron is desiliconized and dephosphorized by using a refining vessel capable of top and bottom blowing and injecting a flux mainly composed of a component consisting of one or more of burnt lime, limestone and iron oxide, the component containing at least iron oxide, into the molten iron, characterized by: injecting a carbon source into the molten iron during desiliconizing reaction and starting the carbon source injection prior to the commencement of said flux injection; preferably starting said flux injection after an ÄSiÜ concentration is lowered to 0.15 mass %; and still more preferably starting said flux injection after the completion of the carbon source injection.