Chemical Thermodynamics and Reaction Kinetics of Bayer Process Desilication

With increasing amount of high silica bauxitesBauxite used as Bayer refinery feed, the re-precipitation of dissolved silicates results in greater volumes of desilication productDesilication products (commonly known as DSP) which corresponds to elevated caustic consumption and issues with bauxite residueBauxite residue neutralisationNeutralisation and storage. Furthermore, incomplete desilication of pregnant Bayer liquor also results in silicate reactor and piping scaling as well as the possibility of contamination of the aluminaAlumina product. Optimization of silicate management in the Bayer processBayer process is therefore a high priority. Understanding the chemistry of silicate leachingLeaching and precipitation of silicate in Bayer processBayer process underpins potential process improvements. This literature review summarises the chemistry of DSPs, with a focus on chemical-thermodynamics and reaction kinetics.