Stepwise Separation and Extraction of Aluminum, Iron and Titanium from Bayer Red Mud in Guangxi, China

Red mud, a strongly alkaline solid waste generated during alumina production, contains valuable metals including aluminum, iron, titanium, and others. Efficient extraction of these metals is of great significance for promoting circular economy development and regional ecological conservation. This paper proposes a stepwise extraction process involving alkali roasting-water leaching to separate Al from Fe and Ti, hydrochloric acid leaching to separate Fe from Ti, and sulfuric acid leaching to extract Ti. Bayer red mud from Guangxi, China was used as the raw material, and the effects of process parameters on the stepwise leaching of Al, Fe, and Ti were systematically investigated. The overall leaching results indicated that the total leaching rates of Al, Fe, and Ti were 99.61%, 99.02%, and 92.75%, respectively. Through comparative analysis of the chemical composition, phase composition, and micromorphology of the raw red mud, roasted clinker, and leaching residues, the stepwise leaching mechanisms of Al, Fe, and Ti were elucidated. Furthermore, the second-stage acid leachate was hydrolyzed, and the H2TiO3 content in the obtained hydrolyzate reached 89.43%, approximately 12 times that of the titanium component in the raw red mud. The Ti hydrolysis recovery rate was 90.41%, and the total Ti recovery rate was 78.65%. Overall, the process enables stepwise extraction of Al, Fe, and Ti, along with the enrichment and recovery of titanium resources, providing an effective reference route for the technical chain of resource utilization of valuable components in red mud.