Valuable Metals Precipitation of Low Grade Nickel Ore Leachate Using Sodium Hydroxide

Abstract

Nickel metal is widely used in various industries. Nickel sources come from nickel sulfide ores and nickel oxide ores (laterite). Nickel content in laterite ore is 1.5-2.5 % (weight basis), lower than the nickel content in sulfide ores. Indonesia is one of the major nickel producers with laterite nickel ore reserves of 1576 million tons or 15 % of total world reserves. The distribution of laterite nickel in Indonesia is found in several regions such as Maluku, Sulawesi and Papua. However, the low grade nickel processing in Indonesia has not been well established. Thus research on valuable metals extraction from ow grade nickel ore has put some interest to some researchers. In this study, precipitation of valuable metals from low grade nickel leachate was conducted using sodium hydroxide as the precipitation reagent. Nickel ore used in this experiment was obtained from Pomalaa, Southeast Sulawesi. After leaching at optimum condition resulting of about 75 % recovery of nickel using HCl (1 M at 90 °C and stirring for 1 hour), the leachate was then added sodium hydroxide to varied pH of 8, 10, and 12. Along with the pH conditioning, temperature was kept to the value of 55 °C, 70 °C, and 85 °C. The optimum nickel recovery of 83.97 % is obtained at pH 12 and temperature of 85 °C. The residual metals concentration in the solution after precipitation was analyzed using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES).