Alumina, or aluminium oxide (Al2O3), is typically produced through the processing of aluminium-bearing minerals found in bauxite. These minerals include gibbsite (γ-Al(OH)3), bӧhmite (γ-AlO(OH)) and diaspore (α-ALO(OH)). Australia produces approximately 28% of the world’s Bauxite and approximately 16% of the world’s alumina (USGS 2018). To date the most widely used process for alumina extraction is the Bayer process. The Bayer process involves a number of key steps including: milling, digestion, desilication, clarification, precipitation and calcination. The refined alumina product from the Bayer process is a dry, pure white, sand-like material.
Alumina produced through the Bayer process is primarily used for the production of aluminium through the process known as the Hall–Héroult process. Additionally it is also often used in refractories, ceramics, polishing and abrasive applications.