Study On Slagging With Dolomite In Converter Steelmaking

In recent years,because of the overcapacity and the low profitability of steel,the iron and steel industry overall depressed.To reduce the cost of production became an important task.Slag-forming material was one of the main cost of converter steelmaking.The use of low cost slag former and slagging method had become the focus of attention of the steelmaking plant.Combining with the production conditions of a converter steelmaking plant,the experiment of dolomite dissolution in converter slag was carried out,and clarified the dissolution mechanism of dolomite;Through thermodynamic calculation and experimental research,analysis and comparison of the effects of dephosphorization of three kinds of methods of slagging with dolomite;Calculation of material balance and heat balance of converter steelmaking,industrial test of dolomite slagging and slag-remaining operation was carried out.The conclusions were as follows:?1?The dissolution mechanism of dolomite and doloma was different,when doloma dissolution,SiO₂ and FeO react dissolution reaction through its pores;when dolomite dissolution,the first occurs in dolomite was cracking pulverization,and then into slag,dissolution reaction happens again,due to the effect of decomposed CO₂ mixing,further promote the dissolution reaction.?2?Dolomite was found to decompose into CaO,MgO and CO₂ in one step at the converter steelmaking temperature.?3?In the early and mid converter steelmaking,low temperature was helpful for dephosphorization;higher basicity improves dephosphorization,when basicity was 1.8or more,it affected little;the area of high content?FeO?,the higher the more favorable dephosphorization,the area of low content of?FeO?was on the contrary.?MgO?content had no effect on the dephosphorization.?4?Use slag-remaining operation,the more remaining slag,the higher basicity of early slag,the more content of?FeO?and?MgO?,the more helpful to dephosphorization.but the early slag temperature slightly higher,and it was not conducive to dephosphorization.But raised temperature appropriately in the early was helpful to the dissolution of slag former,accelerate the speed of slagging,and this was beneficial for dephosphorization.Comprehensive comparison,the effect of dephosphorization of double slag and remaining full slag was similar to double slag and remaining half slag was worse,which was slightly better than single slag.?5?Using dolomite slagging,the phosphorus content in end point liquid steel was126 ppm,resulfurization was 71 ppm,slightly better than using doloma slagging.At same time final slag iron oxide has decreased,improved the metal yield,increase the basicity and MgO and viscosity was proper which was conducive to the maintenance of lining;slag former cost reduced 2.98 yuan per ton of steel.?6?The most suitable double slag and slag-remaining process of dolomite was a large amount of remaining slag even the whole stay,slag-remaining time was about30%,appropriate basicity of final slag and?FeO?content.