Dealkalization Behavior and Leaching Mechanisms of Red Mud with Simulated Aluminum Profile Wastewater

This study presents a new waste treatment strategy by dealkalizing red mud with simulated aluminum profile wastewater. We investigate the leaching behavior and the effect of the wastewater dropping rate. During dealkalization, the slurry pH significantly decreases while conductivity increases, indicating efficient dealkalization. The increase in Na⁺ in the filtrate and the decrease in Na₂O in the residue confirm the dissolution of alkali, especially structural alkali. The dealkalization efficiency reaches 64.4%. Increasing the dropping rate accelerates the reaction, enhancing efficiency without altering the process. The mechanism involves Al³⁺ combining with hydrolyzed AlO₂⁻ to precipitate Al(OH)₃, effectively removing structural alkali, which is the main restrictive factor in red mud. After dealkalization, the utilization rate of red mud increases from 5% to 15%, positively impacting economic and environmental aspects, particularly land occupation, soil salinization, and human health.