Study On Low Cost Converter Steelmaking With High Silicon And High Phosphorus Hot Metal Produced By COREX Technology

This paper focuses on slag consumption,steel materials consumption and slag splashing of high[Si]and[P]content hot metal which produced by COREX furnace steelmaking process of 120 t converter.The approach of low cost steelmaking is proposed through the research about fresh slag reduction technology of high-quality low phosphorus steel,the fresh slag reduction technology of formal deformed steelmaking dephosphorization,the technology of reducing iron consumption in converter billowing process,converter steel melt oxidation controlling at blowing end point,and reasonable splashing slag to extend service life of converter.The approach of low cost steelmaking includes suitable slagging system,slag recycling and all-limestone steelmaking.Under condition of different grades of steel,the reasonable scrap ratio is defined and the consumption of steel materials is reduced.This paper provide theoretical and practical guidance for enterprises to reduce converter steelmaking cost.The influence of molten iron condition,slag composition and blowing end point control on dephosphorization in converter process was studied.A reasonable amount of fresh slag material adding was put forward for high-quality low phosphorus steel.In this way,the consumption of fresh slag material was decreased.The consumption of lime is reduced from 43.37kg/t steel to 38.34kg/t·steel by means of final slag remaining.The influence of return slag recycling on the process of converter slag-making and dephosphorization was also studied.The effect of return slag recycling on the reduction of converter slag-making material consumption was clarified.On the basis of meeting the dephosphorization requirements,the tonnage of steel further reduces lime consumption by 2?5kg/t steel.In order to meet the requirement of middle-quality deformed steelmaking dephosphorization,the research on low cost steelmaking was carried out.The possibility of using full limestone and raw dolomite to make slag for terminal point w[P]=0.030%steel and its influence on converter cost were proved.When the addition amount of limestone is 37kg/t·steel,the addition amount of raw dolomite is 18kg/t·steel,the tests can meet terminal point w[P]=0.030%.(The cost of slag-making material is 4.15 yuan/t.steel,which is 3.69 yuan/t·steel lower than that of using lime and dolomite as slag-making material).On this basis,16kg/t steel return slag is added,and the cost of slag-making material is reduced by 4.39 yuan/t steel.Theoretical calculation and field test proved the quality in continuous operation for slag on middle-quality deformed steelmaking dephosphorization.When blowing end point[P]=0.030%,end point temperature=]660oC,leaving almost 5 t final slag,final slag basicity R=2.45 or higher,increasing amount of final slag is advantaged to the dephosphorization between steel and slag.But after 5 continuous steelmaking with final slag remaining,furnace is need to make fresh slag again.This article reveals the different condition's influence of the molten iron to scrap adding.In low temperature,low[Si]%and low[C]%condition,furnace should reduce the amount of scrap steel;when molten iron w[Si]=0.2%,w[C]=4.2%,hot metal temperature is 1300?,22.5 t scrap steel is suitable.The influence of smelting with less slag on reducing steel consumption is also analyzed.When the molten iron w[Si]=0.3-0.5%,the iron consumption is reduced by smelting with less slag 2.06 kg/t.When the molten iron w[Si]=0.5-0.7%,the iron consumption is reduced by smelting with less slag 1.84 kg/t.To meet the needs of high quality low carbon and low phosphorus steel production,the operation technology of improving the service life of the converter lining and the reasonable slag splashing system are clarified by studying the corrosion mechanism of the converter lining,.Different slag splashing systems are adopted to protect furnace slag splashing according to different end components of steel.The theoretical addition amount of dolomite required was defined,and the theoretical addition amount model of dolomite in slag splashing process was established.