Dehydroxylation of high-energy ball-milled diasporic bauxite

In this study, diasporic bauxite was mechanically activated for different durations (15, 30, 60, 90 and 120 min) by the planetary mono mill. The speed of the main disk and ball-to-mass ratio were kept constant at 600 rev min⁻¹ and 25, respectively. The chemical composition of the ore was determined via X-ray fluorescence. Structural changes and thermal behavior were examined by X-ray diffraction analysis (XRD), Scanning electron microscopy (SEM), differential thermal analysis–thermogravimetry (DTA-TG) and Fourier transform infrared spectroscopy (FTIR). Diaspore, hematite and anatase were detected at XRD analysis, and with an increment in activation time, the intensity of the peaks decreased, and position and width of the peaks changed as well. In DTA analysis, with mechanical activation, the temperature of the endothermic peak that corresponds to dehydroxylation of the aluminum hydroxide was lowered and area of the peak was decreased. These results mean that the structure was disordered with mechanical activation.