Energy Recovery in Bayer Alumina Calcination
D. Ilievski, P. Hay, G. Mills, G. Bauer, A. Unal
waste heat recovery, commercial alumina production
Alcoa has been investigating methods for reducing energy consumption and GHG emissions in alumina refining. This paper reports the results of studies into methods for reducing the energy used in calcination. One study considered using low grade waste heat from calcination to drive a power cycle for generating electricity. The Kalina cycle and the Organic Rankine cycle were considered. The study focussed on the Kalina cycle because of its higher efficiency at lower heat source temperatures. The findings of a feasibility study at one of Alcoa’s Atlantic alumina refineries will be discussed. Another study developed and evaluated flowsheets for using low grade waste heat from calcination to evaporate spent liquor. The circuits use readily available process equipment. The study, based on Alcoa’s West Australian operations, showed significant capability to reduce plant steam generation requirements.
Nanotech 2008 Conference Program Abstract