Recovery of sludge from alumina production

The carbonation of the sludge slurry was studied. The main characteristics of the initial and carbonated red mud were compared. The carbonation of sludge ensures reduction of the toxicity of a sludge field and enables extraction of some rare metals (scandium, zirconium, titanium), aluminum, and sodium. The possibility of using the treated sludge as an additive in the manufacture of cement and concrete products was determined.