Recovery of alkali and alumina from Bayer red mud by the calcification–carbonation method

Red mud produced in the Bayer process is a hazardous solid waste because of its high alkalinity; however, it is rich in valuable components such as titanium, iron, and aluminum. In this study, a novel calcification–carbonation method was developed to recover alkali and alumina from Bayer red mud under mild reaction conditions. Batch experiments were performed to evaluate the potential effects of important parameters such as temperature, amount of CaO added, and COpartial pressure on the recovery of alkali and alumina. The results showed that 95.2% alkali and 75.0% alumina were recovered from red mud with decreases in the mass ratios of NaO to FeOand of AlOto FeOfrom 0.42 and 0.89 to 0.02 and 0.22, respectively. The processed red mud with less than 0.5wt% NaO can potentially be used as a construction material.