Hazards and Dealkalization Technology of Red Mud—A Critical Review

Red mud is a highly alkaline residue generated during the alumina extraction process, and its strong alkalinity significantly hinders its extensive and comprehensive utilization. The alkali in red mud mainly exists in two forms, namely, soluble alkali and insoluble chemically bound alkali. This study aims to provide a comprehensive overview of the dealkalization process progress for red mud, encompassing acid neutralization technology, salt (ion) precipitation or displacement technology, and metallurgical technology. The mechanisms, advantages, and disadvantages associated with each technology are discussed. To enhance readability for readers, mind maps are included for each dealkalization method of red mud. Based on the above analysis, it is advisable to choose the most suitable dealkalization method for red mud, considering its specific properties and the subsequent application strategy. Recommendations regarding future research on red mud dealkalization are proposed.