Study On The Related Technology Of Low-cost Of Converter Steelmaking And Model Development

Concerning the problems of high-consumption of slag and high-Fe content in slag during a 100-ton converter steelmaking process,the countermeasure of the reutilization of final slag and reduction of(T.Fe)in the slag was proposed for the steel grades with the requirement in different phosphorus contents by utilization of final slag technology,decreasing(T.Fe)content in final slag,optimal slag and development of steelmaking cost model.Meanwhile,the models of the addition of optimal slag at the appropriate time and cost control were developed,which can provide theoretical basis for lowering the cost of converter steelmaking in industrial application and practice.The results show that the activities of components in slag have a small influence on liquid steel composition and dephosphorization when the(P2O5)content in slag is controlled within 3%.Limited conditions of sustainable reutilization of final slag was identified with simulation of FactSage7.0.For 100-ton converter,phosphorus content of steel could be lowered less than 0.020%with sustainable reutilization of final slag,when the remaining slag is less than 3-ton,R(CaO/SiO2)is greater than 2.5 and(P2O5)content is smaller than 3%.It is beneficial to realize sustainable reutilization of final slag with high(P2O5)content under the condition that R(CaO/SiO2)is greater than 3.5,the oxygen content in liquid steel at final point is greater than 0.05%and the(FeO)content is greater than 20%.The reason why the granulated iron content in final slag was high was clarified.The countermeasures,such as control of(SiO2)content in slag and increase in tapping temperature,were put forward.Granulated iron of slag could be decreased from 8.1%to 0.5%,the cost of converter steelmaking was decreased by 18.24 yuan/t.The relation of(T.Fe)content with the intensity of bottom blowing,amounts of iron-containing scraps,adding time decarburization speeds and final carbon content was revealed.The target that[C]>0.06%with(T.Fe)?15%and[C]>0.1%with(T.Fe)?12.5%could be realized.For[P]?0.025%in liquid steel,the(T.Fe)content could be decreased to a value less than 14%,and the cost was reduced by 3.5 yuan/t.The effect of composition and consumption of slag on dephosphorization was analyzed based on theoretical calculation.Optimal slag technology was put forward and tested.Through using solid steel slag,the rational matching of different slag material and adopting measures to promote the balance of steel and slag,consumption of new slag material was reduced to 40 kg/t.decreasing the cost 6.29 yuan/t.The phosphorus content of steel can satisfy the requirements of steel,realizing stable production.Through controlling the amounts and charging time of slag,the structure of slag was optimized immediately,decreasing the cost of slag.For[P]?0.015%of 100-ton convertor,the consumption of slag could be decreased from 81.85 kg/t to 69.99 kg/t.Predicting model of composition of liquid steel and slag during smelting process was developed.Predicting model of phosphorus content was developed based on the slag composition of prediction model and the molten pool temperature.Under the condition of the carbon content of steel is more than 0.08%,the predictions of carbon during smelting process and final phosphorus content is within 0.014%,the carbon content can be controlled within ±0.02%and 30 ppm of the actual value,respectively.The steelmaking cost model was developed based on the decreasing(T.Fe)of final slag technology with utilization of final slag technology and optimal slag technology.Maximum cost deviations of models prediction and actual value was 20 yuan and relative deviation was less than 0.6%,playing an active role in guiding the cost control of converter steelmaking.