Crystallization and purification of nickel sulfate hexahydrate from agromining leach solution
Year: 2026
Type: article
Abstract: from a synthetic nickel-rich sulfate solution formulated to reproduce the composition of post-solvent extraction (SX) feed obtained from a bio-ore leach solution (BLS), with a particular focus on impurity partitioning, incorporation mechanisms, and post-crystallization purification. Evaporative crystallization enabled efficient nickel recovery while rejecting most impurities into the mother liquor. However, selective incorporation of Co(ii) and Fe(ii) into the crystal phase was observed, whereas K, Mg(ii), Ca(ii), and Mn(ii) were largely excluded. Controlled dissolution experiments revealed distinct impurity uptake mechanisms, including surface adsorption for Ca(ii), growth-induced inclusions for Co(ii), Fe(ii), and Mg(ii), and mixed inclusion/solution entrapment for K, while Mn(ii) was completely eliminated by crystallization. These mechanisms were corroborated by impurity distribution coefficients, incorporation ratios, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analyses. A simple displacement washing step effectively removed surface-associated and interstitial impurities, increasing the purity of nickel sulfate hexahydrate to 99.99 wt%, with a single washing stage sufficient to meet battery-grade specifications. Overall, these findings demonstrate that the relatively low impurity-to-nickel ratio of the post-SX agromining-derived feed favors efficient impurity rejection during crystallization, highlighting the potential of agromining as an attractive alternative nickel source for the sustainable production of battery-grade nickel sulfate hexahydrate.
Source: RSC Advances
DOI: 10.1039/d6ra06711e
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,042
Funder: Bpifrance
OpenAlex ID: W7223697994