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.