科研之友
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摘要
Direct production of ferromolybdenum from molybdenite (MoS2), in the presence of lime as a desulfurizing reagent using combustion synthesis process is investigated. Thermodynamic calculations and measurement of the adiabatic temperature of the reaction denoted that the process is in agreement with the Merzhanov criterion for self-sustaining processes. The experimental results indicated a relatively complete separation between the molten metal droplets and the co-existing slag. The slag and metal phases were characterized by X-ray diffraction, electron microscopy and wet chemical analysis techniques. It was found that sulfur is mainly distributed into the slag in the form of solid calcium sulfide (CaS). The Lack of calcium oxide in the slag indicated a complete desulfurization reaction between lime and the sulfur in molybdenum sulfide. Characterization of the molted metal revealed that only two phases namely Fe3Mo3C and Fe3Mo exist in the melt. Mass balance calculations showed an Iron molybdenum recovery greater than 85%. Analyses of the phases indicated that a significant amount of Fe3Mo3C phase (60-70 wt%) is present in ferromolybdenum molten droplets even though the raw materials were low in carbon. Chemical analysis and microstructural studies of the raw materials and the products showed that carbon is not present in sufficient quantities to produce this amount of Fe3Mo3C; therefore the structure of this phase should contain a high concentration of carbon vacancies. The deviation of Fe3Mo3C1-x peaks in X-ray diffraction pattern compared to its standard reference peaks and a calculated 0.02% decrease in the lattice parameter of this phase are evidence of the presence of these carbon vacancies.
