New crystal growth modifiers for the Bayer process

In the Bayer process, Crystal Growth Modifiers (CGMs) are used to help increase the production of alumina trihydrate and improve quality. Recent work aimed at mechanistic issues has led to the development of a second generation of CGMs. Traditional, first generation products were known to impact three critical process areas; trihydrate particle sizing, oxalate stability and oxalate morphology. While some plants utilize all three properties to enhance and control trihydrate precipitation, it has long been recognized that not all three properties are always desirable and that products with a more selective impact could provide even greater benefits. The development of the second-generation CGM product range has focused not only on developing products that are more effective, but also products that are more selective in their properties. Results on a range of new formulations are presented.