Technology study of ammonia leaching high-grade nickel matte and preparation of battery-grade nickel sulfate

Aiming to sulfuric acid leaching process to produce battery-grade nickel sulfate via high-grade nickel matte has high demands for equipment with operations and lengthy purification process, et al, the technological route of ammonia leaching of high-grade nickel matte and the preparation of battery-grade nickel sulfate from the ammonia leaching solution were studied. The results show that by controlling the molar ratio of nickel to total NH3 to be 1:6, reaction temperature to be 60 ℃, the weight ratio of liquid to solid to be 7.5:1, oxygen partial pressure to be 2 MPa, and reaction time to be 2 h in the (NH4)2SO4-NH3-H2O system, nickel leaching efficiency can reach 99.14% by one-step leaching high-grade nickel matte from lateritic nickel ore, as well as receives the ammonia leaching solution of 90.018 g/L nickel concentration is obtained whose impurity element mass concentrations are all below 0.95 g/L. Using LIX 54-100 as extracting agent and controlling volume usage, the volume ratio of organic phase to liquid, and extraction time, via four-step solvent extraction for the ammonia leaching solution can achieve efficient removal of impurity elements, with only a marginal decrease of 2.3% in nickel concentration. For the 4th raffinate, after evaporating ammonia and adding sulfuric acid, folloewed by filtration, crystallization, pyrosis, dissolution, and adjusting the solution pH and crystallizing, NiSO4·6H2O can be produced to meet the Class I criteria of GB/T 26524—2023. This technological pathway exhibits features of high efficiency, streamlined processing, and low energy consumption. © 2024 Central South University. All rights reserved.