The Bayer process is widely used for the production of alumina from aluminium containing ores such as bauxite. Typically, alumina is extracted from bauxite using concentrated caustic and subsequent recovery of alumina is achieved by precipitation, using liquor cooling, in combination with seeding. The solubility of alumina in caustic is influenced by a number of factors of which the major two are temperature and caustic concentration. Even though temperature difference is used to control the precipitation reaction, the principal determinant of alumina solubility is caustic concentration. Control of the level of causticity in Bayer liquor, after bauxite digestion and clarification, can have a much greater impact on precipitation yield than temperature. A description of a novel approach for the extraction and recovery of caustic from Bayer liquor, which can yield substantial increases in alumina precipitation yield with respect to current practice, will be reported in this paper. This method towards increasing yield has never been applied to alumina refining. Details of the theory, experimental results and application of the concept will be provided.