Study on the Dealkalization Technics of Bayer-process Red Mud with CO_2 by Carbonation

In the present work,using CO2gas to react with red mud slurry to remove alkali from alkaline red mud through three-phase carbonization method has been studied. The influence of liquid to solid ratio,reaction temperature, time, gas pressure on dealkalization rate were investigated under the condition of CO2feed rate 0. 3 L / min. The research results showed that 50% alkali could be removed from red mud under conditions of liquid to solid ratio 7,reaction temperature 50 ℃,reaction pressure 4MPa and reaction time 2 h. The red mud has low level of alkali after dealkalization,and will not do harm to soil and the source of underground water.