Kinetics of selective chlorination of pre-reduced limonitic nickel laterite using hydrogen chloride

Abstract

The selective chlorination process of pre-reduced limonitic nickel laterite using hydrogen chloride was investigated in this work. In HCl–O 2–H 2O–N 2 atmosphere, the effects of variations in temperature, the partial pressures of hydrogen chloride, oxygen and water vapor, and total gas flow rate were all studied. It was found that the chlorination of nickel and cobalt could be described by two stages; and it was controlled by gas diffusion through product layer. Four apparent activation energies, including 20.43 kJ/mol and 12.89 kJ/mol for the first and second stage of nickel chlorination, 14.95 kJ/mol and 13.02 kJ/mol for the first and second stage of cobalt chlorination respectively, were obtained in the temperature range of 420–460 °C. And the apparent reaction order of hydrogen chloride was also obtained. During the selective chlorination, the oxidation of pre-reduced ore could take place with the selected conditions; chlorinated iron was mostly rejected as hematite and thus nickel and cobalt were selectively chlorinated by hydrogen chloride.