Application Of Liquid Silver In Related Research On FeO Electrolytic Reduction In Molten Slag

Today the environmental protection and energy saving problem have become increasingly prominent,the disadvantages of traditional metallurgical technology is becoming obvious.A new technology of metal extraction——“reduction with controlled oxygen flow” was developed for environmental protection,however the fundamental research related to this technology is relatively lacking,one of the reasons is that it is difficult to find a suitable electrode.Liquid Ag has a good electrical conductivity,strong oxidation resistance.Iron almost doesn't dissolve in the liquid Ag.Based on these characteristics,the application of liquid silver in related research of FeO electrolytic reduction in molten slag was studied in this paper so as to provide reference for expanding the scope of application of Ag in metallurgy and development of future technique on the reduction with controlled oxygen flow.Firstly,the MgO-partially stabilized zirconia was used to constitute a cell with controlled oxygen flow.By using the linear scanning curves,the composition of CaO-SiO₂-Al₂O₃-MgO-FeO slag system in favor of electrolytic reduction of extraction of iron was determined.And based on this composition,the activity of Fe O in the slag was measured using a new device constitute by zirconia solid electrolyte tube containing liquid Ag.The results showed that the open circuit potential value decreased with the increase of the content of FeO in the molten slag,and corresponding activity of FeO increased.The measured values of the activity of FeO were between the calculated values from the thermodynamic software FactSage and from the regular ion solution model.The results also showed that slag activity showed positive deviation relative to ideal solution.Using liquid silver and iron rod as the working electrode,respectively,the open circuit potential,linear scanning voltammetry and cyclic voltammetry were used to study the electrochemical behavior of FeO in CaO-SiO₂-Al₂O₃-MgO-FeO molten slag.It was found that the cyclic voltammetry curves were unstable and in poor reproducibility when the Ir wire was inserted into the liquid silver as the working electrode.So the liquid silver didn't suitable as material for a working electrode for high temperature electrochemical behavior analysis of molten slag.Using MgO or Y₂O₃ stabilized zirconia tube as a separation membrane between anode and cathode,investigations were carried out on extraction of metal iron from 5.2%CaO-42.3%SiO₂-8.1%Al₂O₃-14.4%MgO-10%FeO?wB?molten slag contained in the iron crucible as a cathode with applied voltage of 1.5V?or 2V?in the temperatures of 1623,1673,1723 K,respectively.The results showed that the higher temperature favoured the precipitation of iron dendrites.And the higher the temperature,the more iron dendrites formed.The precipitation of iron dendrites in the iron crucible were related to the resistance of the slag between anode and cathode.If the zirconia tube was closer to the wall of the iron crucible,it would more easy to precipitate iron dendrites.The corrosion of zirconia solid electrolyte tube is mainly through the way of slag penetration,also accompanied by a small amount of solution of ZrO₂.No obvious new phase formation was found at the interface between slag and zirconia.Between the temperature of 1623 to 1723 K,the lower the temperature,more serious the corrosion of zirconia tube would be.This may be because that the content of unreduced FeO in the slag was very high at low temperature.