Sulfur dioxide absorption in a bubbling reactor with suspensions of Bayer red mud

In this work, we studied the SO2 absorption with suspensions of Bayer red mud (the solid residue of the Bayer process for alumina production from bauxite) using a laboratory-scale bubbling reactor with continuous feed of both gas and liquid phases. A few preliminary tests were carried out in order to calculate the physical mass transfer coefficients in both the gas and liquid sides. Then, the ability of red mud suspensions for sulfur dioxide absorption was studied at several different flow rates of both the liquid and gas streams. The absorption rate was measured for four different suspension concentrations. The absorption phenomena were modeled using the film theory and assuming two different fluid dynamics for the gas phase. The liquid-side mass transfer coefficient and the enhancement factor for chemical absorption were calculated from the experimental results using the model.