Performance of new crystal growth modifiers in Bayer liquor

A significant amount of research has been conducted to investigate the mechanistic effects of crystal growth modifiers (CGM's) on the crystallization of aluminum trihydrate. From this work, it was postulated that a CGM modified seed surface possessed a high surface energy and also induced a strong adhesive interaction force between particles and nuclei. Under specific process conditions, this mechanism would allow for both enhanced agglomeration and coarsening of the particles and, also, secondary nucleation control. Current research efforts have utilized the information gained from mechanistic studies to enhance the performance of CGM products. This paper summarizes the performance of two new CGM formulations. The effect of the new CGM formulations is discussed, not only in terms of the coarsening and yield of aluminum trihydrate, but also more specifically in relation to the stability and morphology of sodium oxalate. The results demonstrate that the new CGM formulations show a range of properties with enhanced performance when compared to the current commercial products.