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Thermodynamic calculation, ab initio molecular dynamics (AIMD) and vacuum decomposition experiments were performed to study the volatilization behaviors of Mo and S from molybdenite concentrate by vacuum decomposition. In thermodynamic calculation, starting decomposition temperatures of reactions were calculated, and saturated vapor pressures of Mo, S and MoS2 were also analyzed. In AIMD, geometries of the S n (n≤8), Mo m (m≤8) and Mo m S n (m+n≤8) clusters have been optimized using density functional theory (DFT) with generalized gradient approximation (GGA). And these clusters were simulated in DFT with Cambridge Sequential Total Energy Package (CASTEP) code of Material Studio software. Structures and stabilities of these clusters before and after molecular dynamics simulations were discussed, and diffusion coefficients were also calculated. In vacuum decomposition experiments, relationship between heat preservation time and volatilization rate of Mo and S was obtained, while the constant temperature and chamber pressure were 1823 K and 5–35 Pa, respectively. Above all, both the theoretical and experimental results showed that volatilization behaviors of Mo and S during vacuum decomposition process of molybdenite concentrate were as follows: Mo could partly evaporate into the condensate in the form of clusters, and S could easily evaporate into the condensate.

The feasibility study of the AlCl(g) generated by Al2O−AlCl2−C system under vacuum was carried out by thermodynamic analysis and CASTEP package of the Material Studio program which was based on density functional theory (DFT) formalism. Thermodynamic calculations indicate that AlCl and CO molecules can be formed under conditions of temperature 1760 K and the pressure of 60 Pa. The interaction of Al2O and AlCl2 with C shows that the chemical adsorption of Al2O and AlCl2 does take place on C(001) crystal plane, and at the same time, new chemical bond is formed between Al atom in Al2O and Cl atoms from one of the Al—Cl bonds in AlCl2. The results, after 1.25 ps dynamics simulation, indicate that adsorbed AlCl molecules are generated and CO molecule will be formed in this system, and they will escape from C(001) surface after a longer period of dynamic simulation time. It means that the reaction of Al2O and AlCl2 with C can be carried out under given constraint condition.