Alkalinity Precipitation Measurement on Carbonation of Bauxite Residue

Abstract

The alumina production Bayer process generates 0.7 to 2.0 ton of Bauxite residue (BR) and an average of 1.0 ton of CO2 per ton of alumina produced. The direct use of exhaust gases to react and reduce the alkalinity of BR may allow a triple gain: improving the storage conditions, opening a range of new applications for BR and sequester from 16 to 102 kg of CO2 per ton of alumina. This paper shows the first results of a lab scale program to measure the effects of adding different percentages of CaO and MgO before carbonation in order to precipitate the alkalinity on stable compounds.. The inlet and exhaust gases were analyzed. The precipitate after carbonation was evaluated to monitor the amount of stable compounds like dawsonite. The pH of the suspension was monitored during and after the reaction to evaluate the buffer effect.