Effect of Concentrations and Pressures of CO_2 on Calcification-Carbonation Treatment of Bauxite Residue

摘要

The calcification-carbonization process is attracting attention as a new, feasible method for clean production of alumina and treatment of red mud. The carbonization stage within the overall process was investigated, and the effects of CO_2 concentration and pressure on the recovery of sodium oxide and alumina from red mud were studied in detail. The results showed that when the CO_2 total pressure is 1.2 MPa and the CO_2 concentration is 99.99%, the recovery of alumina and sodium oxide reached 40.08% and 93.16%, respectively. Similar results can also be achieved when the CO_2 partial pressure is 1.2 MPa and the CO_2 concentration is only 60%. And the main phase of solid slag is converted from hydrogarnet to CaCO_3. This study aims to provide a theoretical basis for the industrialization of calcification-carbonization method.