High temperature processs for causticisation of a bayer liquor

- 43 A high temperature causticisation process for the causticisation of a Bayer process liquor is disclosed. The process comprises the steps of: a) adding a quantity of a causticising agent 5 to the Bayer process liquor in a reactor vessel operating at a target reaction pressure for a given target reaction temperature, b) allowing the causticising agent to react with the Bayer process liquor for a sufficient residence time to produce a reaction slurry comprising a quantity of reaction solids in a causticised Bayer liquor; and, c) subjecting the reaction slurry to solid/liquid separation at a target separation temperature to produce a separated 10 stream of reaction solids and a product stream of clarified cauticised Bayer liquor. The process is characterised in that the target reaction temperature is not less than 11 5'C and the target separation temperature is not less than 11 5'C. Figure 1.