Kinetics study of leaching ore nickel laterite using hydrochloric acid in atmosphere pressure

Abstract

Leaching of nickel laterite ore at atmospheric pressure is a leaching method that can be operated at >100⁰C temperatures in an atmospheric pressure, which is applicable to a low-grade laterite ore. This research aimed to study the effect of temperature, acid concentration, and leaching time on nickel extraction percentage and the leaching kinetics. Hydrochloric acid (HCl) was used as a leaching agent and several variables were applied, i.e., temperature (80⁰C, 90⁰C, 100⁰C), HCl concentration (5 M, 6 M, 7 M), and leaching duration (120 minutes, 150 minutes, 180 minutes) to investigate their effect on nickel extraction percentage. In addition, the kinetics of the leaching process was studied using a Shrinking Core Model. The results showed that the percentage of nickel extraction increased with increasing temperature, HCl concentration, and leaching time. The lowest percentage of nickel extraction of 51.29% was obtained when 80⁰C, five molar HCl, and 120 minutes leaching duration were applied. In contrast, the highest percentage of nickel extraction of 97.22% was obtained at 100⁰C, seven molar HCl, and 180 minutes of leaching time. The kinetics study results show that diffusion through the unreacted solid product layer controls the nickel leaching rate.