In Fig. 4.1, the numbers 150-200-250 on the graphs of equilibrium relate to caustic soda concentrations in Na 2 CO 3.A/C denotes aluminate ion concentration as Al 2 O 3 (A)/caustic soda concentration as Na 2 CO 3 (C). A typical Bayer process cycle with low temperature digestion is also shown. Virtually each bauxite contains more or less …