METHOD OF EXTRACTING ALUMINUM OXIDE FROM ALUMINA PRODUCTION WASTES Russian patent published in 2019 - IPC C01F7/06 C22B3/12 B01J3/00 

FIELD: technological processes.

SUBSTANCE: invention can be used in processing of waste red muds of alumina production, in particular, from red mud in Bayer process. Method of extracting aluminum oxide from alumina production includes autoclave leaching of wastes at high temperature and pressure in presence of lime in alkaline solution with subsequent cooling of pulp after leaching, addition of water, mixing and filtration. Note here that lime burnt at 1,200–1,400 °C, taken in amount necessary to obtain ratio of CaO/SiO₂, equal to 1.5–2.0. Leaching is performed at liquid: solid ratio equal to (4.5–4.8):1, at pressure of 37–40 MPa. After pulp cooling, distilled water is added at temperature of 90–100 °C to obtain a liquid:solid ratio of (9.8–10.0):1.

EFFECT: invention increases degree of extraction of aluminum oxide in solution from wastes of alumina production to 85–90 %.

1 cl, 2 ex