Research On Anode Eletrochemical Dissolution Of High-carbon Ferrochrome And Electrodeposition Of Chromium In An Ion-exchange Membrane Reactor

Electrodeposition of chromium powder and anode dissolution of high carbon ferrochrome was studied in an ion-exchange membrane electrolytic reactor. Experimental parameters were optimized.The study of cathode deposition of chromium powder shows that sodium acetateanhydrous and urea are the best combination agent. Current efficiency and the stability of trivalent chromium electrodeposition system were improved by pre-electrolysis process. The cell voltage of electrodeposition of chromium powder in an ion-exchange membrane electrolyzer less than the traditional process significantly. The pH within a stable range was the premise of a high current efficiency. The elevation of the temperature can reduce the cell voltage. The current efficiency can be improved significantly by adding hydrogen resistance agent. Optimal conditions were: time of pre-electrolysis process of9min, initial pH of1.5, current density of500A/m2, hydrogen resistance agent of20mg/L, temperature of23℃.The anode dissolution of high carbon ferrochrome indicated that high current density and high temperature could increase release rate of chromium ion and iron ion from high carbon ferrochrome. In the presence of high concentration of chloride ion, the current efficiency of the anode increased significantly. The passivation of anode did not occured during the long time electrolysis experiments. Optimized conditions of anode were: concentration of hydrochloric acid of2mol/L, current density of800A/m2, temperature of53℃, the concentration of sodium chloride of2mol/L.Electrodeposition of chromium power and anodic dissolution of high carbon ferrochrome showed that cathode current efficiency and energy consumption were mainly affected by the cathode factors. Anode current efficiency was mainly affected by the anode factors. Cathode potential was mainly affected by temperature and current density of cathode, however, anode potential was mainly affected by temperature and sodium chloride concentration. Cell voltage was mostly affected by the sodium chloride concentration and cathode current density. The optimized technology conditions were as follows: the concentration of Cr3+of25g/L, anhydrous sodium acetate concentration of30g/L, the urea concentration of10g/L, the concentration of boric acid of60g/L, the concentration of the hydrogen resistance agent of20mg/L, the concentration of sodium chloride of2mol/L, the concentration of hydrochloric acid of2mol/L, the current density of500A/m2, the anoxic current density of800A/m2, initial pH of1.5, the temperature of53℃.