Bauxite refinery residue neutralization using active wet carbonation technique

Bauxite refinery residue (red mud) is a solid by-product of the alumina refinery industry in which bauxite ore undergoes Bayer Process to produce alumina, which is then converted into aluminium. In fact, the amount of red mud (RM) is numerous, for each ton of alumina product yields 1 to 2 tons of RM. RM is a caustic material (pH 10-13) and carries valuable metals and minerals. Its disposal entangles intricate processes thus, conventional disposal practices comprise depositing it in open dams. The volume of RM continues to accumulate, and these acts possess the potential disaster to harm both environmental along with human health. Previous studies have show RM as environmental remedies, particularly for CO2 capture from flue gas. This study examines the RM originated from Indonesia to neutralize using active wet carbonation technique. The RM-cake-clay-form with 25.5% water content is transformed into a 40% solid content slurry then contacted using CO2 industrial grade at room temperature and atmospheric pressure at gas flowrate 5 L/min for 120 min. According to the study that has been conducted, CO2 showed its potential to neutralized the RM alkalinity from pH 11.25 to 7.44 and generate mineral-carbonate compounds with estimated sequestration capacity 1.424 g CO2/100 g RM from the obtained carbonated filtrate through bicarbonate and carbonate ion presence.