Development of real-time weight monitoring system for the carbothermic reduction process of silica

Abstract

For many years the production of solar-grade silicon remained a costly process resulting in a large amount of carbon gas being emitted, and so the process still requires improvement to suppress carbon emission. The starting point of the processes is to produce raw silicon materials from a natural resource via mostly carbothermic reduction. However, this process is very complicated and SiO and SiC form as by-products. Further improvement of the carbothermic reduction process requires an understanding in real time of the reactions occurring and the weight change during heating. In particular, the behavior of the SiO by-product plays a major role in the production of silicon because the loss of Si is caused by the escape of SiO gas. In this study, we developed an in-situ weight measuring system for our induction heating furnace, and successfully suppressed much of the error in weight by improving the crucible configuration. The real-time monitoring of the crucible weight loss during the reaction may assist in understanding of the carbothermic reduction process in a more detailed fashion.