Effect of Eh on the rate and mechanism of the transformation of goethite into hematite in a high temperature acid leach process

Conversion of goethite into hematite is the critical reaction for high temperature acid leaching of nickel laterite ores. The transformation occurs by dissolution of goethite and precipitation of hematite. It is shown that the dissolution stage of this process may be faster or slower than the precipitation stage, depending upon the oxidation potential of the solution. At lower potentials in the presence of Fe2+, goethite dissolution is faster than hematite precipitation