CONTROL OF PHOSPHORUS CONTENT OF MOLTEN STEEL IN CONVERTER

摘要

PURPOSE:To control freely phosphorus content in molten steel to the desired level by a method wherein in the operation of a pure oxygen up-blow converter the amount of iron oxide coolant, which is used to obtain the desired phosphorus content, is calculated from an estimate expression for the phosphorus content in the molten steel at the end of blow smelting obtained from the analysis of prior date value, and the calculated amount of the iron oxide coolant is thrown into the converter. CONSTITUTION:In the operation of a pure oxygen up-blow converter, expected amounts of iron oxide coolant and CaO thrown into the converter are determined by static model, etc. before blow smelting. The desired end- point value of C, the desired end-point value of the molten steel temperature and the measured value of P in molten iron are input into a computer. An expected value of phosphorus amount in molten steel at the end of blow smelting is calculated from an estimate expression of phosphorus content at the end of blow smelting obtained from the operation data in the past. In this case, the amount of iron oxide coolant thrown into the converter and the amount of C in the molten steel at the end of blow smelting are set up as substitutes for the temperature of the molten steel, the amounts of CaO and FeO in slag, which are main factors for dephosphorization. The values of P,C and temperature and the amount of CaO thrown into the converter are established by basing on the expected value of P, and are input together with the amount of P of molten iron into the computer to determine the amount of iron oxide coolant thrown into the converter. The molten steel having the desired phosphorus content can be obtained by throwing the determined amount of iron oxide into the converter.