All-Russian Scientific-Research Institute of Chemical Technologies, Moscow, Russia:

V. Yu. Koltsov, Head of Department, e-mail: basilik2@yandex.ru

This article gives the results of thermodynamic calculations of oxidized nickel ore sulfatization process. For the purpose of determination of detailed ore sulfatization processes, the conversions of metal oxides into sulfates (Gibbs energies) were calculated, using reference data-based thermodynamic indices. There was made a definition that negative Gibbs energy amounts for sulfuric acid interaction of cobalt and nickel oxides are between 273 and 1273 K. The “TERRA” software was used for reaction sequence and priority determination. Thermodynamic research, proceeded using this software, made it possible to simulate nickel oxidized ore sulfatization process and determine thermodynamic phase equilibrium mechanisms of this multicomponent system. “TERRA” initial data used the composition system of valuable elements' oxides (nickel, cobalt, magnesium, aluminum, iron). There were described the thermodynamic models of slightly injected sulfuric acid sulfatization cases. Mutual insolubility conditions system status was presented together with condensed products composition graphic dependence. There was made a determination, that chemical resistance of main metals' oxides (nickel, cobalt, magnesium, aluminum, iron) have a specific sequence during sulfuric acid chemical interaction. There was determined, that formation of iron sulfate is the last after reaction of sulfuric acid with the rest of oxides. This fact is very important during implementation of sulfatization process, because nickel is isomorphic component of iron minerals and its extraction is impossible without destruction of these minerals. High temperature sulfates decomposition sequence was determined as a thermodynamic calculations result. Iron sulfate decomposition temperature is the lowest (about 600 ^oC). According to this, during temperature growth, aluminum, nickel, cobalt and magnesium sulfates turn into oxides. This factor can be used for conversion of preferential elements into insoluble form and following selective leaching of nickel and cobalt.

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