Role of Cooling Temperature on Impurities Precipitation of Metal Sulfate Solution Derived from Crude Ferronickel Leaching Using MgO

Abstract

Nickel is used as a raw material for Nickel Manganese Cobalt (NMC) batteries as a compound of Nickel Sulphate Hexahydrate (NiSO4.6H2O). This study used nickel laterite as ore. A hydrometallurgical process carries out Ferronickel to extract nickel concentrate. The first step is leaching using 2M H2SO4 solution for 6 hours with a stirring speed of 200 rpm at 90°C. The leached solution was then neutralized using a neutralizing agent MgO 5% w/w until it reached a pH of 3.5. The neutralized filtrate was then filtered to separate the filtrate and the residue. The neutralization process produces magnesium sulfate salt (MgSO4), which is an impurity. Next, the cooling temperature method is used to precipitate MgSO4 crystals. In this study, the variation of the MgSO4 cooling temperature used was -5, 0, and 5 °C. Subsequently, crystallization was carried out to produce NiSO4.6H2O. The highest nickel recovery (59.61%) can be achieved using a cooling temperature of -5 °C. Also, by using -5 °C of cooling temperature, the nickel content of crystal product is 2.75%. The crystallization product still contains other compounds, such as MgSO4, FeSO4, and CoSO4.