Digester Design Using CFD

In the Bayer process, dissolution of gibbsite and kaolinite occur in the digester train. Understanding the hydrodynamics of the digester is key to improving the extent of dissolution, and thus the extraction of alumina and re-precipitation of silica. Deviation from ideal plug flow results in a miscalculation of the slurry retention time. The outcome may be a loss of undigested alumina to the red mud with a consequent reduction in extraction efficiency.