Experimental Study on the Energy Change and Microstructure of Roasted Bentonite

Abstract

Sodium bentonite was roasted at different temperatures, and the raw ore and roasting products were analysed via thermogravimetry‒differential scanning calorimetry (TG‒DSC), X-ray diffraction (XRD), and scanning electron microscopy-energy dispersive spectroscopy (SEM‒EDS). The changes in energy, microphase, and microform during the roasting process were investigated. The diffraction peaks of montmorillonite, the main sodium bentonite phase, broadened and decreased significantly during roasting below 700°C, and the degree of curling at the edges of the bentonite particles increased with increasing temperature. After roasting at 900°C, the diffraction peaks of montmorillonite disappeared, many amorphous phases were observed, the edges of the particles appeared fused, the particles were adherent, and the curling was reduced. After roasting at 1100°C, the amorphous phase recrystallized, the diffraction peak of quartz significantly increased, and most of the bentonite particles were in a molten state and adhered together. The bentonite roasted at 700~900°C was used as a filling material additive, not only to ensure a certain degree of expansion but also to improve the activity of volcanic ash. These results provided theoretical support for the use of roasted bentonite in mine filling materials to.