Electrochemical Reduction Mechanism Of Zinc And Iron In Molten Salt

As a harmful substance in zinc metallurgy,ZnFe₂O₄ needs to destroy its crystal structure in order to recover zinc and iron.Most of the main treatment methods for ZnFe₂O₄ in the industry have the disadvantages of high energy consumption,large pollution,complicated process flow,and difficult residue treatment.In order to obtain zinc and iron elements directly,ZnFe₂O₄ is subjected to zinc-iron separation by molten salt electro-deoxidation,and the electrochemical reduction mechanism of ZnFe₂O₄ is studied.The thermodynamic analysis shows that the electrolytic reduction process of ZnFe₂O₄ is: ZnFe₂O₄ →FeO + ZnO →Fe + ZnO →Fe + Zn.And ZnFe₂O₄ is physically dissolved in NaCl-CaCl2 melts.The study of electrochemical reduction of ZnFe₂O₄ by electrochemical methods shows that the reduction process is a three-step process: The reduction ofFe³⁺ and Zn²⁺ is a quasi-reversible electrochemical reduction process controlled by diffusion on the Pt electrode,and a reversible and irreversible electrochemical reduction process controlled by diffusion on the Mo electrode.By studying the influence of electrolytic voltage,electrolytic temperature,electrolytic time and the influence of the intermediate product Ca₂Fe₂O₅ in the electro-deoxidation process,it is shown that under the condition of 800℃ electrolysis for 8h,with the gradual increase of voltage,the step-reduction process of ZnFe₂O₄ is: ZnFe₂O₄ →FeO + ZnO →Fe + ZnO →Fe + Zn.The intermediate Ca₂Fe₂O₅ is produced in the process of deoxidization,which has certain influence on fractional reduction and current change of ZnFe₂O₄ electro-deoxidation process.At the temperature of 800°C and a voltage of 1.8 V,full separation of zinc and iron can be achieved in melts for 8 hours of electrolysis.