Dealkalization of Bauxite Residue Through Acid Neutralization and Its Revegetation Potential

Bauxite residue is a highly alkaline industrial solid waste generated through the alumina production process. Its high alkalinity causes serious environmental pollution. In this article, a fast, high-efficiency, low-cost dealkalization process was developed. Bauxite residue was dealkalized by sulfuric acid and CAM, a calcium-containing compound. The revegetation potential of dealkali bauxite residue was also studied. The dealkalization rate reached up to 94.31% when 18.4% sulfuric acid was added, and 2% CAM leaching occurred at room temperature for 10–30 min. The filtration speed increased by about 70 times with the addition of CAM up to 4.5%. The subsequent pot experiment showed that the dealkali bauxite residue met the growth requirements of plants. Scanning electron microscopy analysis showed that the particle size of neutralized bauxite residue was enlarged, thereby accelerating the soil formation process of the bauxite residue. This work provides technical support for ecologic restoration of a bauxite residue disposal area.