Hydrophobic deep eutectic solvents for the direct leaching of nickel laterite ores: Selectivity and reusability investigations

The emergence of the battery society has resulted in an unprecedented strain on the supply of battery metals, such as nickel, cobalt, and manganese. Consequently, there is an urgent need to develop processing technology for low-grade nickel laterite ores, which are abundant in resources but challenging to process using conventional hydrometallurgy. In the present study, a hydrophobic deep eutectic solvent (DES) was employed for the first time to leach and recover battery metals from a nickel laterite ore. The DES, which was prepared by decanoic acid and trialkylmethylammonium chloride, was expected to regulate the coordination environment by limiting water and providing ligands for the target metals to be stabilized in the DES. As intended, this direct laterite leaching by the DES facilitated the selective leaching of battery metals with iron, while suppressing the leaching of magnesium and silicon which are primary impurities in the laterite ore. Furthermore, stripping and scrubbing of the metals from the DES enabled the selective recovery of battery metals from iron and even allowed for the repeated use of the DES for at least four cycles of the leaching. The proposed process offers a pathway to recover the critical battery metals from abundant magnesium-rich nickel laterite ores.