Abstract: The present invention relates to compositions and methods to increase the output of a high quality product from the precipitation liquor crystallization process exemplified through the aluminum hydroxide recovery processes such as the Bayer process. The invention is a method of increasing the size of precipitates from a liquor. The invention in one embodiment relates to the use of a crystal growth modifier compositions added to the precipitation process to increase the particle size distribution of the precipitated alumina trihydrate.

Abstract: The present invention relates ways to increase the output of a high quality product from the precipitation liquor crystallization process exemplified through the aluminum hydroxide recovery processes such as the Bayer process. The invention is a method of increasing the size of precipitated of a liquor. The invention in one embodiment relates to the use of a crystal growth modifier compositions added to the precipitation process to increase the particle size distribution of the precipitated alumina trihydrate.

Abstract: The invention provides a method of controlling silica in the liquor circuit of the Bayer process. The method involves addition of a promoter material to enhance the precipitation of DSP and includes adding one or more silica dispersion materials or dry silica forms to those parts of the circuit where precipitation of DSP and removal of silica from solution is desirable; for example the desilication stage of a Bayer process plant. The removal of DSP from solution reduces silica concentration in the liquor and thereby enables better control of process issues such as silica contamination in alumina product and DSP formation in later stages of the process where precipitation as scale onto vessel walls and equipment is problematical. As a result, the invention provides a significant reduction in the total cost of operating a Bayer process.

Abstract: The invention provides a method of controlling silica in the liquor circuit of the Bayer process. The method involves addition of a promoter material to enhance the precipitation of DSP and includes adding one or more silica dispersion materials or dry silica forms to those parts of the circuit where precipitation of DSP and removal of silica from solution is desirable; for example the desilication stage of a Bayer process plant. The removal of DSP from solution reduces silica concentration in the liquor and thereby enables better control of process issues such as silica contamination in alumina product and DSP formation in later stages of the process where precipitation as scale onto vessel walls and equipment is problematical. As a result, the invention provides a significant reduction in the total cost of operating a Bayer process.