Electroleaching kinetics of molybdenite concentrate of Sarcheshmeh copper complex in chloride media

Abstract

The kinetics of molybdenum and copper extraction from Sarcheshmeh molybdenite concentrate (Kerman, Iran) was studied by electroleaching process in batch mode. The effects of several critical parameters including sodium chloride concentration, pH, temperature, time, operating voltage, and the sodium carbonate addition on the molybdenum and copper extraction from the concentrate were investigated. Results showed that the molybdenum extraction significantly increased by increasing sodium chloride concentration, temperature, time, operating voltage, and sodium carbonate addition during the process. While with increasing pH, the molybdenum extraction decreased. Maximum molybdenum extraction (89%) was obtained at the sodium hypochlorite concentration of 30 g/L, the pH of 9, the temperature of 50 °C, operating voltage of 5 V, and reaction time of 4 h. Copper extraction was determined 17.5% in 30 min, which decreased to 3.9% over 8 h. It was found that carbonate ions added to the electroleaching process had a significant effect on molybdenum extraction. Also, carbonate ions might prevent hypochlorite decomposition by stabilizing copper (III) ions. The catalytic compounds of copper precipitate simultaneously with the catalytic decomposition of the hypochlorite. Kinetic studies have shown that the dissolution of molybdenite concentrate is described by a shrinking core model controlled by a chemical reaction. The activation energy for the electroleaching process of molybdenite concentrate was determined to be 29.4 kJ/mol. It seems that electroleaching is an efficient, green, and selective process for treating molybdenite concentrates.