USE OF FLUE GAS FOR CARBONATION OF BAUXITE RESIDUE

Alcoa World Alumina Australia has been investigating residue carbonation as a potential major improvement opportunity for achieving residue storage with lower environmental risk and reduced long term liability. Results from comprehensive laboratory studies, pilot scale trials and operation of a full scale prototype carbonation facility have demonstrated the full scale viability of this technology. However, the current process requires a stream of concentrated CO₂ which is mixed with a thickened residue slurry prior to deposition of this slurry into drying beds as a part of Alcoa’s current residue dry stacking.

Alcoa is currently investigating an alternative approach to residue carbonation which avoids the need to separate and concentrate CO₂ from a dilute flue gas stream. This paper details this novel approach to residue carbonation, outlining the findings from preliminary testing and describing how this process of residue carbonation may be integrated into the refining and residue storage operations.