Abstract:Carbon powder was added in smelting process to improve quality of products in vacuum decomposition process and reduce impurity contents of Si, Ca, Mg, and Al in product. Distribution of main impurity elements of Si, Ca, Mg, and Al in molybdenite concentrates was studied. The results show that carbon addition into concentrates facilitates removal of impurities of SiO2, MgO, Al2O3, and CaO. Within the temperature range in the study, removal rate of Si is about 100%, removal rate of Mg is about 99.7%, and removal rate of Al is about 78.44%. Removal rate can be further improved with increase of carbon content and extension of time. The best removal rate of Ca is about 9.8%. With a low-grade molybdenite concentrate of 48% as raw material under the condition of vacuum smelting with carbon powder, Mo content in obtained product is about 92%, content of S drops to 0.69%, contents of main impurity element is SiO2 0.0021%, Cu<0.005%, P<0.005%, Mg 0.001%, Al 0.64%, and Fe 4.44%. Element of Fe is not removed at all.