Pilot test of bauxite residue carbonation with flue gas

Abstract

The Bayer process alumina production 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: improve the storage conditions, open a range of new applications for BR and sequester from 33 to 102 kg of CO2 per ton of alumina. This paper shows a pilot scale reaction of a suspension of bauxite residue in water with flue gas, produced from direct oil burning. Three different types of reactors were used: one spray tower and two packed columns. The inlet and exhaust gases were analyzed using electrochemical and non dispersive infrared sensors. The pH of the suspension was monitored during and after the reaction to evaluate the buffer effect.