Study Of Smelting Of Lead Sulfide Mixed With Iron-sinking Residuals And The Behavior Of Arsenic

The direct smelting method has been widely used in lead smelting process because of its simple smelting process,short process,low energy consumption,high productivity,high efficiency of equipment bed and good utilization of waste heat.The Kivcet is the most successful direct method in the lead smelting process,which has the characteristics of strong adaptability to raw materials in addition to the above advantages.Iron-sinking residuals produced by the purification in the process of zinc hydrometallurgy contain a variety of valuable metals,high metal recycling value.However,the disposal process of iron-sinking residuals is relatively complex,energy consumption,serious pollution,which serious restricts the sustainable development of the zinc smelting.Therefore,how to scientifically and rationally deal with the heavy iron slag is an urgent problem to be solved.Based on the above situation,this paper puts forward the process of using the Kivcet to deal with the iron-sinking residuals,and using the high temperature oxidation and reduction smelting to efficiently recover the valuable metals in iron-sinking residuals.However,the basic theoretical research on the lead process of lead sulphide concentrate collocation iron-sinking residuals is almost blank,especially the research on the behavior of zinc ferrite and arsenic.In order to explore the suitable technological conditions of the new process,the decomposition mechanism,phase tranformation of zinc ferrite were detected.On the basis of this,the process of the oxidation and reduction smelting of lead sulfide mixed with iron-sinking residuals and the behavior of arsenic were optimized.In order to investigate the behavior of arsenic in the whole smelting process,the change rule and distribution characteristics of arsenic were studied.The researches show that when the temperature is within the range of 500°C-1000°C,lead sulfide and zinc sulfide can be oxidized to lead oxide,zinc oxide or lead sulfate or zinc sulfate,and the trend of producing lead sulfate or zinc sulfate is stronger than lead oxide or zinc oxide.Lead sulfate is more easily reduced to elemental lead than lead oxide.When the temperature is within the range of 600°C-1000°C,zinc ferrite can be reduced to Fe₃O₄,ZnO,FeO and Fe.When the reduction temperature is 800°C,C/ZnFe₂O₄=1/4,reduction time,80 min,the decomposition rate of zinc ferrite is about 94%.The carbothermal reduction process of zinc ferric was controlled by the interface chemical reaction,and the activation energy was 24.65kJ/mol.When the reduction temperature of 1250°C,CaO/SiO₂=0.4,FeO/SiO₂=1.0,the mass ratio of lead sulfide concentrate and iron-sinking residuals oxidation production,4:1,the crude lead grade and direct recovery rate of lead reached 97.76%and 97.76%respectively.The arsenic is in the form of FeAsS and As₂S₃ in lead sulfide concentrates,and it is mainly in the form of arsenite in its calcine.arsenic mainly exists in the form of As₂O₃ in the calcine of iron-sinking residuals.50.24%of the elemental arsenic enters the crude lead,and arsenic in the reduction slag is mainly in the form of arsenate,accounting for 12.3%of the total arsenic.Arsenic in ash is mainly in the form of As₂O₃,which accounts for 37.46%of total arsenic.It can be seen from the above that it is feasible that smelting of lead sulfide mixed with iron-sinking residuals.The behavior of arsenic provides a basis for the control of arsenic contamination and the harmless treatment of arsenic.