Preparation of hollow spheres from quartz particles have been reported. First, quartz hollow spheres with CaCO3 binder were prepared in following process; 1) adhesion of quartz particles (component particles) to oil droplets in alkaline CaCl2 solution and 2) precipitation of binder CaCO3 onto quartz surface, by introduction of gaseous CO2 into the system. The spheres were further calcined at 1000 °C, immersed in acidic solution and then washed with distilled water. The resulting spheres were found to form cagelike structure: adjacent particles within a resulting sphere became sintered by calcination, while each sphere was not be fused together. EDX analysis showed intense distribution of Ca solved into sintered phase between quartz particles. XRD pattern of the calcined spheres still indicated intense profile of quartz crystal. Formation mechanism of quartz hollow spheres with CaCO3 binder was examined. CaOH + adsorption onto quartz and oil droplet surfaces was considered to be necessary for the above both steps 1) and 2). It was monitored that the precipitation on the quartz particles would begin first at the irregular edges which face its adjacent component particle, and then extend over the outside or inside of the hollow spheres. Thus it was considered that concentrated CaO from binder CaCO3 would enhance sintering between the particles by calcination.
ASJC Scopus subject areas
- Chemical Engineering(all)