The manufacture of tricalcium aluminate

In the Bayer Process, production of alumina is limited by the rate of liquor passing through Kelly Presses. Kelly Presses are utilized for secondary clarification, and filter clothes in combination with Tricalcium Aluminate (TCA) are used to trap solids after the initial clarification in gravity settlers. Desirable qualities of TCA permit fast liquor flow rates and filtering solids to low concentrations. Inconsistent performance of Kelly Presses is not fully understood, so this paper offers some explanation on how physical and chemical conditions in TCA production govern desirable properties. Slaking temperature, lime to alumina ratio, and soda concentration affect TCA particle size distribution, crystal structure, and composition. TCA particle size distribution, crystal structure, and composition are thought to affect the flow of liquor through Kelly Presses. By controlling slaking conditions of TCA, Kaiser's Gramercy Works has reduced the number of daily press dumps by 33%.