IMPACTS OF THE REFINERY PROCESS ON THE QUALITY OF SMELTER GRADE ALUMINA

Quality specifications for smelter grade alumina at Queensland Alumina Limited (QAL) are based on the requirements for its use in smelters (as feed to reduction cells and gas treatment centres), and on QAL’s process capabilities. Although this may seem relatively simple, smelter requirements vary with respect to operating technologies and procedures, while QAL’s capability is also impacted by many factors related to refinery technology, operation and raw material quality.

In general, smelters are requesting alumina that is low in impurities and dust content, and that gives increased dissolution rates. The expectation is continually for more consistent product.

This paper considers some of the alumina quality parameters that are important to smelters, and reviews how these parameters are controlled within the refinery. Impacts on the refinery process will also be considered.

While the paper gives broad comments based on external literature, it draws primarily from QAL experiences and in particular from observations during the commissioning of the Gas Suspension Calciners (GSC).