Kinetics of Carbothermal Reduction of Quartz Under Vacuum

Publisher Website
Google Scholar
Abstract
The kinetics of reduction of 0.2 mol of –70?mesh quartz particles by 0.2 mol of graphite were determined in a batch reactor between 0.25 and 10−0torr. The effects of temperature, CO partial pressure, SiO2phase transformation, and alkali and alkaline‐earth oxide additives on the rate of reaction were studied. Increasing CO overpressure retarded carbothermal reduction. At 1400−C, addition of 5 wt% alkali oxide inhibited the reaction, whereas the same amount of alkaline‐earth oxide decreased the induction time; CaO was the best promoter. The initial reaction rate obeyed the cubic power law of nucleation growth at weight losses <15%, with an apparent activation energy of 77 kcal/mol. At higher weight losses, the Austin‐Rickett equation with an exponent near 2 was more applicable. The results are consistent with a model based on a transitory phase intermediate.

This publication has 3 references indexed in Scilit: