| Abstract Scope |
In Bayer process, during digestion, reactive silica present in bauxite dissolves and reacts with caustic soda to form sodalite. Formation of sodalite affects process efficiency and operational costs. It also contributes to scaling in equipment, increased BR generation, and heightened liquor viscosity, all of which hinder process performance and product quality.
Conventional methods like increase in residence time in predesilication, addition of lime, reduction in target A/C, increase in digestion temperature and time improved the desilication efficiency. However, the effects observed are not very consistent when the liquor causticity is high at ~95%. In this study, as innovative approach to control liquor silica level in liquor is attempted by reducing liquor causticity to ~89% with the addition of carbonate to Bayer liquor. The result indicated a significant drop in liquor silica ratio from 1.43 to 1.27 which helps in controlling silica impurities and scaling in the process. |