The kinetics and mechanism of interaction of wolframite concentrate with potassium carbonate during sintering in the temperature range of 25–1000 °C were studied. The sequence of phase transformations in an oxidizing atmosphere of air was established using thermal, X-ray spectral and X-ray phase analyses, as well as gas mass spectrometry. It was shown that in the temperature range of 520–820 °C, water-soluble potassium tungstate, its eutectic mixture with the initial reagent, and ferrite phases, iron and manganese oxides with a variable oxidation state are formed. A change in the wolframite composition during sintering was revealed, accompanied by a decrease in the proportion of iron, which is confirmed by an increase in the unit cell parameters of the FeMnWO phase. The kinetics of the process is described by a single-stage model with a dominant effect of autocatalytic nucleation, the activation energy is 56.6–56.9 kJ/mol. The obtained results are important for the development of technologies for processing wolframite concentrates to obtain soluble compounds.
Pikulin et al. (Wed,) studied this question.