Structural change of mechanically activated molybdenite and the effect of mechanical activation on molybdenite

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denite is also used as an important raw material of oxidization roasting for the preparation of ammonium molybdate in molybdenum industry [7,8] and as one of the main naturally metallic minerals associated with gold. [9] Furthermore, the extraction of nonferrous metals from sulfide ores belongs to the technically difficult and economically important tasks. The more chemically stable the sulfide, the more difficult the extraction is. Thus, either drastic reaction conditions have to be applied or the chemical stability of sulfides has to be modified by a suitable chosen preleaching treatment. The mechanical activation of the ore by intensive grinding is a typical representation of the second way. [10] In our previous investigation, [11‐16] mechanical activation of galena, pyrite, and sphalerite can effectively reinforce the corresponding hydrometallurgical processes, but galena, pyrite, and sphalerite have different mechanisms of mechanical activation, which owes to different structural changes during mechanical activation of sulfide ores. Therefore, it is meaningful to investigate the effect of mechanical activation on molybdenite by studying the oxidation behavior and the structural changes of nonactivated and mechanically activated molybdenite. In this article, natural molybdenite ore was purchased from a domestic concentration plant, and its chemical compositions are presented in Table I. It was found by X-ray diffraction (XRD) analysis that the natural molybdenite contained hexagonal molybdenite as a predominant component. The natural molybdenite was floated with � 50 ppm xanthate as a floatation reagent. Forty grams of floated molybdenite and 200 mL CCl4 were added into a 250 mL flask, refluxed for 72 hours, and then filtrated to leave xanthate in the filtrate and obtain a filter residue; the filtrate residue was dried at 80 °C in vacuum to get nonactivated molybdenite. Mechanically activated molybdenites are obtained by grinding nonactivated molybdenite as in Reference 16 for 40, 120, 260, and 480 minutes, respectively.