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.