Abstract
The effects of non-stoichiometries on the oxidative leaching reactions of heazlewoodite samples in nitric acid solutions were examined from the kinetic point of view, carrying out the determination of leaching rates, the measurement of electric resistivity and so on.
Main results obtained are as follows:
(1) The oxidative leaching rates of heazlewoodite samples in nitric acid solutions were influenced greatly by the stoichiometries of the ores. Reaction with nickel-rich heazlewoodite proceeds faster than that with nickel-deficient ones.
(2) The electric properties of heazlewoodite samples were not influenced by the change in the stoichiometries of the ores. Therefore, the electric properties of heazlewoodite do not normally play a significant part in oxidative leaching reaction.
(3) The oxidative leaching reaction of heazlewoodite is a simultaneous reaction of sulfate ion formation and elemental sulfur formation.
(4) The overall reaction of oxidative leaching of the ores in nitric acid solutions is controled by a chemical reaction step, and the rate equation is given by the following equation.
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