Effect of pH on Precipitation of Ferronickel Leaching Solution by Using MgO for Mixed Sulfate Precipitate Synthesis

The increasing demand for electric vehicles affects the high demand for nickel-based batteries, including Nickel Manganese Cobalt (NMC) batteries. Generally, NMC is processed from high-quality ore (sulfide ore) to produce nickel (II) sulfate hexahydrate or NiSO4.6H2O. But sulfide ore face scarcity due to a long history of mining and exploitation. Thus, laterite-type nickel ore can be an alternative to nickel resources. This study aims to produce mixed sulfate precipitates from a ferronickel leaching solution that can be utilized further to produce NiSO4.6H2O. Also, this research will study the pH effect of the precipitation process on the product's elemental composition, recovery, and compounds formed. The precipitation process was conducted using 5% MgO (weight basis) with a pH range of 2.5 to 6.5 with one increment. The mixed sulfate precipitates were characterized using AAS, EDX, and XRD. When using a pH of 3.5, a nickel concentration of 1473.00 ppm, nickel recovery of 23.02%, and Nickel grade of 3.18% could be obtained. As a result, the phase of NiSO4.6H2O was formed. Also, the other phases were formed after precipitation, such as CoSO4, FeSO4, and MgSO4.