Selective and efficient extraction of nickel and cobalt from laterite ores using the sulfation-roasting and leaching-precipitation process with H2O2 and surfactant addition

The recovery of nickel (Ni) and cobalt (Co) from laterite ores has attracted significant attention due to the increasing demand for these metals in electric vehicle (EV) batteries. While the sulfation-roasting-leaching process offers a viable route for extracting Ni and Co from laterite ores, the co-extraction of iron (Fe) remains a major challenge. To address this, the present study investigated the selective extraction of Ni and Co by optimizing equilibrium pH control and introducing stearyl trimethyl ammonium chloride (STAC), a cationic surfactant, during the leaching stage. Controlling the equilibrium pH of the slurry in the absence of STAC improved the selectivity of leaching Ni and Co over Fe. However, this pH adjustment also reduced the extraction of Ni and Co due to their adsorption onto hydroxide precipitates. Remarkably, the addition of STAC significantly enhanced Ni and Co recovery by modifying the surface properties of the leach residues. Mechanistic analysis revealed that STAC increased the zeta potential of the surface of residue particles and reduced particle agglomeration. These changes inhibited the adsorption and co-precipitation of Ni²⁺ and Co²⁺ with residues. Under optimized conditions (equilibrium pH 3.5 with 0.1 wt% STAC), the extraction reached 97.7 % for Ni and 97.4 % for Co, while Fe extraction was suppressed to 0.2 %. These results demonstrate a promising strategy for achieving high selectivity and efficiency in Ni/Co recovery from laterite ores, offering potential advantages over conventional hydrometallurgical approaches.