IMPROVED BAYER CAUSTICISATION

摘要

An improved process for the causticisation of Bayer liquors in an alumina refinery, the process including the steps of reacting lime with aluminate io ns in a Bayer liquor within a primary reactor under controlled conditions of lo w to moderate temperature (between 70-80 ~C) and agitation, to form substantially only a hydrocalumite species and hydroxyl ions; and a secondar y reactor wherein said hydrocalumite species formed is subjected to heating in contact with a Bayer liquor under controlled conditions so as to cause the hydrocalumite species to react with the liquor to form calcium carbonate, aluminate ions and hydroxyl ions, whereby a causticised Bayer liquor is obtained and wherein the efficiency of lime utilisation is substantially increased and/or alumina losses are minimised.