Mechanism of influence of ferric ion on electrogenerative leaching of sulfide minerals with FeCl3
(1. Department of Chemistry and Environmental Engineering, Changsha University of Science and Technology, Changsha 410077, China;
2. School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China)
2. School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China)
Abstract: A dual cell system was used to study the influence of ferric ion on the electrogenerative leaching of sulfide minerals. Reaction mechanisms for the ferric chloride electrogenerative leaching of a series of sulfide minerals were proposed based on the data collected from the dual cell experiments. The influences of ferric ion on the electrogenerative leaching of sulfide minerals are similar. Ferric ion plays an important role on limiting the electrogenerative leaching rate at a relatively low concentration of FeCl3 (about less than 0.15 mol/L). The mathematical models based on the Butler-Volmer relation were delineated, and kinetic equations with respect to ferric ions for each sulfide mineral were obtained. The kinetic equations show that when the concentration of ferric ion is relatively low, the electrogenerative leaching rates are predicted to be proportional to 6/7, 4/5, 2/3 and 2/3 order of ferric ion for nickel concentrate, chalcopyrite concentrate, sphalerite and galena respectively. As the concentration of ferric ion increase, the correlative dependence between electrogenerative leaching rate and concentration of ferric ion becomes weak. The above conclusions are in agreement with the experimental results.
Key words: ferric ion; sulfide minerals; electrogenerative leaching; leaching rate; mechanism