Pressure acid leaching of arid-region nickel laterite ore. Part III: Effect of process water on nickel losses in the residue

The nickel containing phases in both residues include amorphous silica, hematite, alunite/jarosite and chromite. Comparing the amount of nickel associated with each phase highlights the difference that sodium sulfate additive has on the amounts of nickel associated with hematite, but especially silica. It appears that the reduction in nickel associated with these two phases is responsible for the majority of the observed increase in nickel extraction.