Abstract:Bayer digestion process was conducted by simulating technological condition of production field with diasporic bauxite as raw material. The effect of A/S ratio on technical and economic index of Bayer digestion was investigated. The results indicate that A/S ratio of bauxite exerts big effect on technical and economic index such as alumina digestion rate, output ratio of red mud, alkali consumption and ore consumption. When A/S ratio is 4~7, A/S ratio drops by 1, digestion rate of alumina drops by about 3~5 percent point, output ratio of red mud rises by about 0.05 t/t-ore, alkali consumption rises by about 14.21 kg/t-AO, and ore consumption rises by about 0.13t/t-AO.