Sedimentation and separation of red mud is an extremely complicated physical and chemical process. The Bayer process dissolving pulp is a suspension formed by red mud and sodium aluminate solution. Due to the complex physical and chemical interactions between the red mud particles and the solution, the phase composition, distribution, surface morphology of red mud particles, solid content of red mud slurry, liquid phase composition, red mud slurry temperature, etc. all have significant effects on the sedimentation and separation process of red mud slurry.

By adding specific flocculant can greatly increase the settle speed of solid-liquid separation. The mechanism of high-molecular flocculants lies in the effective coagulation between the red mud particles through adsorption bridges, surface adsorption and charge neutralization, and the formation of "large particles", which greatly accelerates the setting velocity. Different dissolutions of pulps have different properties, and the appropriate polymer flocculants must be selected through experiments before achieving high efficient separation of red mud on site.