HPAL of a lateritic nickel ore: An investigation on the relationship between nickel and cobalt extraction and acid consumption

Nickel and cobalt raw materials have become essential in industries like batteries such as robotics, and drones, which are considered as future technologies due to their expanding applications and diversity. Research towards the development of environmentally friendly and relatively low-cost alternative methods for extracting nickel, particularly from low-grade deposits, is becoming increasingly crucial. Laterite ores processing is plagued by high reagent consumption and scale formation. This study focused on investigating the relationship between Ni and Co extraction and acid consumption in the high-pressure acid leaching of lateritic ore, as well as the characterization of leach residue. Analysis has shown that the lateritic ore contains 1.05 % Ni, 0.05 % Co and 21.94 % Fe. In the acid leaching tests based upon a Box-Behnken Design, the initial acid concentration and leach time have a beneficial effect on the Ni extraction (70-94 %). Cobalt extractions ranged between 93 % and 96 %. To facilitate Fe dissolution and increase Ni extraction, cuprous ions were added into the leach solution. Moderate level copper addition (0.025 M) resulted in a significant improvement in Ni extraction, whereas high levels of cuprous addition (0.050 M) did not have further benefit. It has been noted that adding cuprous ions significantly reduces the amount of scale that forms in the autoclave. The lowest Ni extraction was obtained under two different test conditions that did not include copper ions. Increased acid addition was correlated with the increase in Ni leaching and decreased Fe content in residue. There will exist an optimal situation where the acid addition is enough to enhance Ni dissolution and the Eh condition, leading to minimal dissolved Fe.