An in-depth exploration of the performance and influence of rapid dewatering filter aid for red mud slurry

Red mud is a kind of industrial waste residue produced in the process of alumina production, which has strong suspension and is difficult to precipitate and filter. This study compared the effects of 4 kinds of filter aids, including CaCl₂, polymerized ferrous sulfate (PFS), steel slag (SS), and Portland cement (PC), on the filtration rate, filter cake moisture content, and Na₂O content of red mud slurry. At a dosage of 10 g·L^‒1, the filtration effects were in the following order: PFS > CaCl₂ > SS > PC. Under the combination of 5 g·L^‒1 SS and 5 g·L^‒1 PC, the better filtration effect was achieved with a filtration time of 205.17 s, which was reduced by 58.52% compared to the original red mud. The combined use of SS and PC exhibits better advantages in terms of cost and filtration effect. This study provides a data foundation for the rapid filtration of red mud slurry. The use of SS and PC as filter aids for red mud holds broad application prospects.