PURIFICATION OF SULPHURIC ACID SOLUTIONS FROM THE LEACHING OF NICKELLIFEROUS LATERITES

Low-grade nickelliferous laterites are important sources of nickel and cobalt, accounting for a significant portion of the world's known reserves. This study investigates the purification of sulphuric acid solutions obtained from the leaching of these laterites to enable the simultaneous recovery of nickel and cobalt through hydrometallurgical methods. The research identifies that although sulphuric acid heap leaching can efficiently extract nickel and cobalt, the leach solution becomes contaminated with impurities such as iron, aluminum, and chromium. To address this, we focused on the precipitation processes used to remove metal cations from the solution, particularly the formation of jarosite, a sulfate mineral that precipitates iron in acidic environments. The effectiveness of this method was evaluated to determine the optimal conditions for jarosite precipitation, which involves maintaining a pH below 1.5 and temperature between 90 to 100ºC. The results show that efficient removal of iron, along with other impurities, is achievable, leading to a cleaner solution suitable for subsequent electro-extraction of nickel and cobalt. Overall, this work contributes to improving economic and environmental outcomes in the processing of low-grade nickel laterites.