Alumina for Aluminium Smelting

Around 95% of the commercial production of alumina is destined for the smelting industry. The specification of this material has steadily converged as the design and operation of reduction cells has converged, however significant variation in the performance of alumina in the reduction cell is still observed. Alumina is the largest raw material input into the reduction cell and has the most profound effect on cell thermal stability and process control. In addition alumina plays key roles in the generation and capture of HF from cell emissions and in the general environmental performance of the smelter. The properties which dictate dissolution and contribute to cell excursions, particularly anode effect frequency, are strongly related to particle and crystallographic structure, properties which are challenging to analyse and often not well represented on the specification sheet. This arises from the complex structural relationship of the transition aluminas and for example, the push to progressively increase specific surface area, targeted at aiding dissolution and dry-scrubber performance.

Keywords:

Metallurgical alumina , microstructure , cell emissions , dissolution