Removal of copper and nickel from low grade molybdenite concentrates

Molybdenite concentrates produced by Uranium Corporation of India Ltd., Jadugoda contain excess copper and nickel as per specifications which need removal for quality production of molybdenic acid and ferromolybdenum. The influence of different process variables, such as leaching temperature, leaching period, concentration of leachant, namely cupric chloride, ferric chloride and calcium chloride on the selective dissolution of copper and nickel from the molybdenite concentrates have been studied. Cupric chloride and ferric chloride in the presence of calcium chloride were found to be the effective oxidants for removal of copper and nickel. Addition of calcium chloride enhanced leaching rate, served to lower down the pH of the solution and also to raise the boiling point of the slurry. Over 92% of copper and 74% of nickel were removed from the molybdenite concentrates on leaching with the leachant containing 10g/l CuCl2, 100g/l FeCl3 and 300g/l CuCl2 for a period of hours at 100°C. The loss of molybdenum was less than 1.5%.