Selective precipitation of iron from multi-element PLS produced by atmospheric leaching of Ni-Co bearing laterite

Laterites are the main resources of oxidized nickel in the world. Nickel and cobalt are embedded in limonite laterites within the goethite structure. Therefore, the removal of iron ions will lead to the simultaneous precipitation of iron, nickel, and cobalt. In our previous study investigating atmospheric leaching of laterite ore using sulfuric acid with the addition of NaCl to the solution, we determined the optimal parameters to minimize the co-dissolution of iron. Based on the determined optimum conditions, a PLS was prepared. In the current study, the effect of pH on iron precipitation from the PLS was investigated using sodium hydroxide as a neutralizing agent. Results indicated that a pH=4 can result in the highest removal of iron from the leaching solution (around 90%) while minimizing the loss of nickel and cobalt. The SEM analysis revealed ferrihydrite as the most important mineral in the final precipitation obtained at pH=4. The results of this study can be used for benchmarking more efficient methods for iron removal from the solution and improving the dissolution kinetics of nickel and cobalt.