The Applied Fundamental Research On The Removal Of Tramp Element Arsenic During Steelmaking Process

With the resources of high grade iron ore gradually depleted, the usage amont of low-grade iron ore is increasing year by year. Furthermore, in view of environmental protection and cost reduction, the usage of scrap is increasing significantly. All these facts lead to the percentage of residual element arsenic in steel going up in a large scale. Simultaneously, the user request lower arsenic contenr in steel. For lack of effective solution to dearsenication and theoretical research on dearsenication in molten steel, the iron and steel enterprise faced a technical problem on effective way to dearsenication at current stage. Therefore, how to tower the arsenic content in molten steel has attracted more and more attention to the metallurgical workersThe aim of the present study is to lower the arsenic content in steel, the way to dearsenication was systematatically studied in base molten steel. The study includes in four aspects. Firstly, the thermodynamic study of dearsencation in molten base steel was carried out. Secondly, the relation between dearsencating agent and dearsenication in molten steel was studied. Then the reaction mechanism of dearsenication in molten steel was investigated. Finally, the industrial trial of dearsenication in molten steel was carried out in the LF refine process.The result of thermodynamic study of dearsenciation in molten base steel show:The calcium in the molten steel can be used to dearsenication, only when the calcium content exceed the critical value; the effect of dearsenication can be influenced by the oxygen and surful content in molten steel, but the influence of oxygen content is the most obvious; the higher calcium content in molten steel, the lower equilibrium arsenic content in molten steel; the distribution of arsenic capacity in CaO-SiO2-Al2O3-10%MgO molten slag was studied.The investigation on the relation between dearsencating agent and dearsenication in molten steel show:the influence of different type, proportion and dosage of dearsenicating agent, the temperature, Surful and arsenic content in molten and the slag on dearsenication in molten steel were investigated systematically, then the utilization ratio of calcium alloy and the mass transfer corfficient of arsenic in molten steel were discussed. Three aspects should be considered ensure high efficiency of dearsenication; first was seclection of type of dearsenicating agent; second was the control of slag composition; third was the control of composition in molten steel.The study on the reaction mechanism of dearsenication in molten steel show: the state of product of dearsenication in molten steel and slag was studied by using experimental method; Simultaneously, the reaction mechanism of dearsenication, the relation between desulphurization and dearsenication and the kinetic model about dearsenicaion by calcium alloy were discussed and analyzed; this part of work was helpful to dearsenication in molten steel.The industrial test about dearsenication in molten steel show:the dearsenication in molten steel can be realized in the LF furnace, the surful and calcium content in molten was restrictive factor for dearsenication under industrial condition; the surful content in molten steel had to be recuded before dearsenication in LF furnace; the control level of surful and calcium in molten steel was put forward to ensure the effect of dearsenication.