Abstract: Red mud,a solid waste residue of alumina refinery industrial production,is a serious basic source because of strong basicity.Experiments of dealkalization for alkaline red mud with hot water and CaO water bath method were carried out.Results showed that alkali concentration of CaO-added red mud filtrate was significantly higher than that without CaO,and the more CaO added,the higher of alkaline concentration of the filtrate.Efficient of alkali recovery of red mud with the addition 5% (mass fraction) CaO after three times washing was the highest,and the alkali recovery amount was close to the 3/4 of the total recovery amount.pH of each group of red mud washing liquid had little change and all decreased about 0.5.Efficient of alkali recovery of each group of washing liquid had little relation with the way of previous treatment of red mud,and it was mainly affected by times of washing.  

Key words: red mud, dealkalization, washing