Abstract:Red mud is a strongly alkaline industrial solid waste produced by the Bayer process bauxite refining. The red mud provided by a Bayer process alumina plant in Zunyi was used as a sample to develop a microwave fast dry alkali fixation process, and the principle was studied. The results show that pH value of red mud can be reduced from 10.88 to 8.11 in only 40 minutes after microwave dry process under the conditions including microwave power of 392 W, microwave frequency of 2 450 MHz, and wavelength of 122 mm. The alkali fixation process does not produce secondary pollutants. The analysis results of XRD and SEM show that composition, appearance color, apparent morphology and particle size of red mud are all change.