New methods of laterite processing are emerging particularly in developing simpler, less hazardous, and energy efficient processes as compared to High-Pressure Acid Leaching (HPAL) due to the increasing effort of minimizing greenhouse gas emission from automobiles and fast depletion of high grade nickel ore. Nickel and cobalt are one of the raw materials used in manufacturing electric vehicle batteries. For many years the production of nickel has been dominated by sulfide ores due to ease of processing and the inability of laterite ores to produce high-grade concentrates, however laterite ore exploration is increasing as demand for nickel and cobalt continues.
In this study, a reduction process is performed prior to acidic extraction of low-grade nickel laterite ores gathered from various nickel mining areas in the Philippines. Reduced iron from leach tailings were recovered through the magnetic separation process. Extracted metals which reported to the solution were then precipitated via a multi-stage precipitation process by gradual pH elevation using hydroxides.
Screening and optimization studies were conducted in laboratory and bench scale set up to determine the optimum leaching process parameters. Maximum extraction of 94% Ni, 90% Co and 79%Sc were achieved using the proposed technology. Meanwhile, the multi-stage precipitation process recovered scandium, and mixed nickel-cobalt hydroxide precipitates (MHP), consecutively. Target iron grade of recovered magnetic concentrate from leach tailings is >50% Fe.