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Kinetics and mechanism of oxidation for nickel-containing pyrrhotite tailings
X-ray powder diffraction, scanning electron microscopy, energy dispersive spectroscopy, thermogravimetry, differential scanning calorimetry, and mass spectrometry have been used to study the products of nickel-containing pyrrhotite tailings oxidation by oxygen in the air.The kinetic triplets of oxidation, namely, activation energy(E_a), pre-exponential factor(A), and reaction model(f(α)) being a function of the conversion degree(α), were adjusted by regression analysis. In case of a two-stage process representation, the first step proceeds under autocatalysis control and ends at α = 0.42. The kinetic triplet in the first step is E_a = 262.2 kJ/mol, lg A = 14.53 s~(-1), and f(α) =(1 –α)~(4.11)(1 + 1.51 ×10~(–4)α). For the second step, the process is controlled by the two-dimensional diffusion of the reactants in the layer of oxidation products. The kinetic triplet in the second step is Еa = 215.0 kJ/mol, lg A = 10.28 s~(-1), and f(α) =(–ln(1 –α))~(–1). The obtained empirical formulae for the rate of pyrrhotite tailings oxidation reliably describe the macro-mechanism of the process and can be used to design automatization systems for roasting these materials.
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International Journal of Minerals Metallurgy and Materials
2021年09期
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