Phase and Structure Optimizations of MoS 2 Concentrate Pellets with Al 2 O 3 -SiO 2 Additives During Oxidative and Volatilizing Roasting Process

The novel one-step oxidation–volatilization process for separating MoO 3 from pelletized MoS 2 concentrate supported on a porous Al 2 O 3 -SiO 2 skeleton has been demonstrated to have superior diffusion efficiency compared to the traditional two-step oxidative roasting-sublimation approach. Optimal control of pellet phase and micro-structure evolutions is crucial for maintaining a stable and breathable pellet bed throughout the roasting process, which is essential for industrial application of the new process. This work determined the phase transformations of MoS 2 concentrate pellets during roasting, revealed the formation mechanisms of mullite whiskers from MoS 2 -Al 2 O 3 -SiO 2 system and thus achieved toughening control of roasted MoS 2 concentrate pellets with temperature programmed roasting (TPR). It is found that the intermediate product Al 2 (MoO 4 ) 3 can induce the low-temperature formation of mullite whisker. With TPR, the volatilization rate of molybdenum is 97.2%, and the compressive strength of mullite pellets reach 124.8 N. This study puts forward a feasible route with industrial significance.