CARBONATION OF BAUXITE RESIDUE

Alcoa World Alumina Australia (Alcoa) has been investigating residue carbonation as a potential major improvement opportunity for achieving residue storage with lower environmental risk and reduced potential for long-term management requirements. Comprehensive laboratory and pilot scale testing of residue carbonation was conducted during the period 1991 to1996. Results from these pilot scale trials were promising with carbonated mud pH of 9 being achieved and leachate quality from the drying beds being maintained at around pH 10.

During the design for a drying area expansion at Kwinana in 1998/99, it was decided to include funds for the installation and operation of a full scale prototype carbonation facility, which would allow carbonation of all the residue deposited in this new drying area. This facility was commissioned during mid 2000 and has been the subject of a detailed monitoring and evaluation program. This paper details the findings from this evaluation.