Roasting of pyrophyllite for application in aluminoborosilicate glass production

ABSTRACT Pyrophyllite, an aluminum silicate mineral, was used as a raw material for the production of aluminoborosilicate glass. For the application of pyrophyllite to the glass manufacturing process as a raw material, the particle size distribution of the powder must the following requirements: 150–45 μm ≥ 60 mass% and below 45 μm ≤ 40 mass%. Hence, an attempt was made to develop the technology for pyrophyllite to produce a powder that meets these requirements through understanding the crushing characteristics. Roasting of pyrophyllite at 1150 °C resulted in the alternation of raw pyrophyllite and led to differences in the crushing characteristics. Crushing of the roasted pyrophyllite produced a powder with a reduction in the amount of the fine particles (−45 μm) compared to the powder of the raw pyrophyllite under identical crushing condition. This difference is attributed to the alternation of the raw pyrophyllite after the roasting process, as confirmed by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) results as well as by the amount of water adsorption. The melting characteristics of the raw and roasted pyrophyllite samples were investigated for application to the aluminumborosilicate glass production. The glass products are characterized as colorless and in an amorphous phase.