National University of Science and Technology MISiS, Moscow, Russia:

A. A. Komkov, Associate Professor at the Department of Non-Ferrous Metals and Gold, Candidate of Technical Sciences, e-mail: akomkov@yandex.ru
V. I. Karyaev, Postgraduate Student at the Department of Non-Ferrous Metals and Gold, e-mail: karyaev@mailnord.ru

NORD Engineering LLC, Moscow, Russia:
V. A. Sokolykh, Process Engineer, e-mail: sokolykh@mailnord.ru
A. V. Kuznetsov, Technical Director, e-mail: kuztensov@mailnord.ru

This paper looks at the distribution of molybdenum between the products of matte smelting of molybdenum-bearing copper sulphide material. A thermodynamic analysis has been carried out to understand the behaviour of molybdenum during autogenous smelting of copper concentrates. A laboratory study has been carried out to examine the process of matte smelting of molybdenum-bearing concentrates with different concentrations of copper. The authors analysed the distribution of molybdenum between different compounds in the slag, the ratio of molybdenum distribution between slag and matte, and the extraction of molybdenum in the slag, matte and gas phase. It is demonstrated that the prevailing form in which molybdenum is present in slags includes molybdenum dioxide MoO₂, and its share in the slag may vary from ~60 to ~85 % depending on the smelting process conditions. A significant share of molybdenum in the slag is bonded in the form of calcium molybdate even when the concentration of CaO is relatively low. As the copper concentration in the matte rises, the extraction of molybdenum in the matte decreases, while more molybdenum is extracted in the slag and gas. Depending on the smelting conditions (matte composition, temperature, oxygen concentration in the blast air), within the variation range considered, the extraction of molybdenum in the gas phase can vary from ~3–4 to ~42 %. The results of the thermodynamic analysis and the experimental study are in correlation. At the same time, there were observed inconsistent molybdenum distribution ratios in certain process regimes. Such deviations are mainly attributed to the approximations adopted for thermodynamic calculations, as there are almost no data available today on the activity and the activity ratios of molybdenum-bearing compounds in slag and matte. More experimental research is needed to confirm the quantitative indicators of molybdenum distribution during matte smelting of copper concentrates.

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