Vacuum Thermal Decomposition Of Molybdenite Desulfurization

Our country is a big country of molybdenum resources and producing, but for the low technologyl of dressing and metal melting, the most products are molybdenum iron,high-grade molybdenite, ammonium-based, therefore a new type of industrial melting molybdenum are urgented.The current treatment process of molybdenite is mainly divided into two major categories of law and wet. Pyrometallurgical smelting is roasting molybdenite obtained the sublimation of molybdenum or get molybdenum trioxide though wet, then generated by the hydrogen reduction of molybdenum metal powder. This process has problem of environmental pollution, low recovery of molybdenum. The entire wet process is oxidation of sulfide minerals to oxide or its salts, then purification for further pure molybdenum compounds. Wet process avoid a lot of sulfur gases, improve the recovery rate of metal, but the leaching problem of cost and equipment constraints are a major factor in its development.In this paper, A new method of deal with molybdenite in vacuum to decomposition and desulfuration was proposed. Theoretical analysis and experimental research are study. Experiments show that the thermal decomposition molybdenite in vacuum can get molybdenum and element sulphur.The relationship between pressure and temperature curves calculated through the thermodynamic theory, the pressure is 10-1-103Pa when the decomposition temperature of 1000℃-1600℃.Analytical the TG and DSC date of analytical pure MoS2 decomposition in pure nitrogen. Established a reaction rate equation by using Freeman-Carroll: By the reaction equation can get that n= 3.0003, the activation energy Ea= 727.745 KJ/ mol, pre-exponential factor A= 58.77 x 1022. thermal decomposition desulfuration molybdenite in vacuum was analyzed,get the mechanism of MoS2 decompositionAnalytical pure MoS2, low-grade molybdenite, molybdenum concentrates were carried out thermal decomposition desulfurization experiment by use vacuum furnace. Analysis the influence of decomposition temperature and decomposition time. Detected residues by use of X ray diffraction (XRD), scanning electron microscopy (SEM), chemical analysis,Confirmed residues of molybdenum is the metal molybdenum.Experiments confirmed that molybdenite vacuum thermal decomposition of the desulfurization effect is clear:pure MoS2 get desulfurization rate of 97 percent at decomposition temperature 1300℃, constant temperature time 60min; low-grade molybdenite get desulfurization rate of 99 percent at decomposition temperature 1650℃, constant temperature time 60min;high-grade molybdenite get desulfurization rate of 96.5 percent at decomposition temperature 1500℃, constant temperature time 60min;The experiment draws the conclusion:desulfurization elevates along with thermal decomposition temperature elevates and decomposition time expand. Combination of power consumption that the best decomposition temperature is 1500-1600℃, constant temperature time is 60min for low-grade molybdenite, and the best decomposition temperature is 1500℃, constant temperature time is 60min for high-grade molybdenite.Therefore thermal decomposition molybdenite in vacuum is a pollution-free new metallurgical technology, it has a good prospect of application.