Theoretical And Experimental Studies On In Situ Desulfurization Of Dolomite Alumina

As focus of the steel industry is changing from the scale to the current benefits of quality and variety,improving the quality and performance of steel becomesmore and more important.The performance and quality of steel is largely determined by the sulfur content,how to reduce the sulfur content in steel has attracted much attention from the metallurgical industry.Unlike other impurities that can be removed by oxidation in the converter steelmaking process,sulfur must be removed before entering the converter.Desulfurization outside the molten iron furnace is an effective method that has gained worldwide recognition from steel companies.Although metal magnesium has strong desulfurization ability and wide application,its preparation process is complex and high cost,magnesium desulfurization efficiency is low and the process is complex,so it is necessary to find a new desulfurizer and process to replace the traditional magnesium desulfurizer.This paper,the preparation of magnesium and hot metal desulphurization are combined,and Mg vapor produced by dolomite Al thermal reduction is directly used for hot metal desulphurization without condensation.Using dolomite as new desulfurizer can not only increase its application scope,but also replace the traditional hot metal desulphurization process of dolomite（magnesite,etc.）→metal Mg→passivation Mg particles→hot metal desulphurization.Compared with the traditional metal desulphurization process,the technological process is simplified,the cost is reduced and green metallurgy is realized to a certain extent.The following aspects have been made:the exploration of the heat decomposition of Dolomite,the kinetic analysis of thermodynamic calculation,desulfurization and Mg vapor generation,the experiment of Dolomite aluminum hot in situ desulfurization,and the contrast of Dolomide decerites and other desulfurizers experiment of.Get the conclusions shown below:The thermodynamics of carbon,silicon and aluminum reduction of dolomite and MgO is calculated by using HSC thermodynamic software.The results show that the reduction temperature of aluminothermic reduction of dolomite is low,and the reduction of dolomite can occur at 1533 K,and the existence of CaO can reduce the temperature of aluminothermic reduction of MgO and MgO Al₂O₃.The experiment of thermal decomposition of dolomite shows that the decomposition of dolomite can be divided into two stages,the corresponding temperatures are 743～863 K and 973～1093 K,mainly in the second stage,and the maximum decomposition rates of the first and second stages are about 550 K and 770 K respectively.The control steps are the diffusion of CO₃^2-and the escape of CO₂,which belong to two-dimensional interface reaction and three-dimensional phase interface reaction respectively.The desulfurization experiment shows that the desulfurization rate increases with the extension of reaction time,the increase of temperature,the increase of dolomite and Al addition and the increase of initial sulfur content.The optimal experimental conditions are as follows:the reaction temperature is 1623 K～1723 K,the addition amount of dolomite and Al is 1.1times and 1.3times of the theoretical value,the reaction time is 20 min～30 min,the final desulfurization rate is 90%,and the terminated sulfur content is lower than 50 ppm.CaO can not carry out deep desulphurization and MgO has the phenomenon of desulphurization.Magnesium has a certain solubility in hot metal,and the solubility increases with the increase of temperature.In the desulfurizer of dolomite and CaO/MgO,the more magnesium is formed with the increase of the amount of CaO;MgO occupies the dominant position of desulfurization,and CaO plays an auxiliary role.