Reductive roasting of nickel laterite ore with sodium sulphate for Fe-Ni production. Part II: Phase transformation and grain growth

In Part II, the correlation between Fe–Ni grain growth and characteristic fusion temperatures of the Na2SO4–laterite mixtures, and phase transformations of the reduced pellets were investigated. For the mechanism of sodium sulphate, Na+ is able to liberate the hosted nickel and iron within lizardite, while SO42– is the sulphur source for the formation of Fe–FeS eutectic compound which can decrease the characteristic fusion temperatures to promote the growth of ferronickel grains. The mean particle size of ferronickel increased from 7.4 μm to 48.6 μm with the addition of 20 wt% Na2SO4.