Study on Digestion of Low Grade High Silica Bauxite by Static Roasting

Aiming at the problem of poor digestion performance of alumina from low-grade high-silica bauxite, the low-temperature static roasting and digestion process was used to investigate the effects of roasting temperature, roasting time and ore size on the digestion effect of alumina. The results show that the main phases of aluminum in the ore are boehmite and diaspore, and the decomposition temperature during the roasting process is 515 ℃. After roasting, the structure of the ore becomes a porous and gully structure. Under the conditions of roasting temperature of 600 ℃, roasting time of the 90 s, and ore particle size of 150 μm, the relative digestion rate of alumina is the best, which is 7.57% higher than the raw ore to 97.88%. The limiting link of alumina dissolution from calcined ore is internal diffusion, and its apparent activation energy is 44.72 kJ/mol.