Steel-making Operations By Substituting Dolomites For Some Light-burned Dolomites In Converter

Under the depression environment of iron-steel industry,most of iron-steel plants are considering how to reduce production costs,but also to ensure the quality of the product,The use of low-cost alternative high-cost flux become the trend of reducing cost,Under this background,this paper carried out the research of using light burned dolomite instead of slagging.Based on the basic theory of thermodynamics,the paper analyzes the mechanism of the decomposition of raw dolomite in converter.The decomposition process of raw dolomite in the furnace is described by the shrinking core model.the feasibility of the replacement of light burned dolomite raw slag is proved.At the same time,combined with the production field of smelting data,The interaction between CO₂ and C,Si,Mn,P,Fe（l）and other elements in the decomposition of raw dolomite was studied.The result show that,CO₂ produced by decomposition of raw dolomite can be used as a weak agent to participate in the oxidation reaction of C,Si,Mn,P,Fe（l）and other elements in the Fe solution.For two different compositions of iron,In P_CO =0.1 P⁰、P_CO2= 0.9P⁰,P_CO=0.5P⁰、P_CO2= 0.5P⁰ and P_CO=0.9P⁰、P_CO2= 0.1P⁰ three atmospheres,CO₂ and C,⊿G that CO₂ react with C and Si is less than zero.In P_CO=0.1 P⁰、P_CO2= 0.9P⁰ and P_CO=0.5P⁰、P_CO2=0.5P⁰ two atmospheres,⊿G of CO₂ and Mn,Fe（l）reaction is less than zero.In P_CO=0.9P⁰,P_CO2=0.1P⁰ atmospheres,⊿ G of CO₂ and Fe（l）reaction are greater than zero.The liquid iron of [Mn]=0.25%,reaction is less than zero.While in [Mn]=0.05% liquid iron,reaction increases as the temperature gradually increased to greater than zero.In P_CO =0.1 P⁰,P_CO2= 0.9P⁰ atmospheres,⊿G of CO₂ and P reaction is less than zero.In P_CO =0.5P⁰,P_CO2= 0.5P⁰,P_CO =0.9P⁰,P_CO2= 0.1P⁰ and P CO₂ atmospheres,⊿G of CO₂ and P reaction is greater than zero.The composition of CO₂-CO atmosphere affects the oxidation sequence of C,Si and CO₂ in the Fe liquid,In high concentration CO₂,CO concentration is low,the preferential oxidation of CO₂,C at low CO₂ concentration,the higher concentration of CO,CO₂,Si preferential oxidation.Converter steelmaking using raw dolomite,material balance and heat balance calculation are carried out,and ensure that the replacement ratio of light burned and dolomite is 1:1.93,and The cooling effect of dolomite and scrap-steel is 1:1.56.The result of industrial test showed that,using substituting dolomites for some light-burned dolomites,dephosphorus ratio is between 87% and 92%.Cost analysis shows,using substituting dolomites for some light-burned dolomites,the highest reduced cost is 10.23 Yuan per ton,Cost reduction is Significant.