Institute of Metallurgy of the Ural Branch of the RAS, Ekaterinburg, Russia:

L. Yu. Udoeva, Senior Researcher, e-mail: pcmlab@mail.ru
E. N. Selivanov, Head of Laboratory of Pyrometallurgy of Non-Ferrous Metals
K. V. Pikulin, Junior Researcher

Low content of molybdenium in domestic ores and the remoteness of discovered deposits from the industrial centers of raw materials processing increases significantly the cost price and reduces the competitive ability of the products. To solve the problem, it is necessary to improve technologies and develop new ways of obtaining high-quality products that are in demand in science-intensive industries. The article presents the results of an alkaline pressure leaching study to intensify the process of purification of molybdenite concentrates and to obtain pure molybdenium disulfide from low-grade raw materials (40–45% Mo). The sample of concentrate from South Shameysk deposit showed the possibility to replace a multistage flotation beneficiation by alkali-xylite hydrothermal decomposition of minerals-related impurities contained in the molybdenite concentrate. On the basis of organo-alkaline pressure leaching, we offered the flowsheet for purification of the substandard molybdenite concentrate to pure molybdenium disulfide. The directional change in occurrence forms of impurities in the alkaline product reduces noticeably the number of stages and duration of the subsequent acid processing, the consumption of reagents and the volume of waste solutions containing environmentally hazardous components in comparison with the existing technology for MoS₂ production. The sequence of transformations of silicon-containing and sulfide components at all stages of the flowsheet for purification of molybdenite concentrate was found out with the help of X-ray diffraction analysis, electron microscopy and electron probe microanalysis. The proposed method for obtaining pure molybdenium disulfide is less demanding for the quality of raw materials and applicable to low-grade molybdenite concentrates, which will allow reducing the number of operations and metal losses under an enrichment of poor molybdenium-containing ores.
This work was carried out within the State Task of the Institute of Metallurgy of the Ural Branch of the RAS (subject No. 0396-2015–0082).

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