Aluminum Oxide

Aluminum oxide is the most common industrial mineral in use today. Fused aluminum oxide is produced synthetically by melting bauxite and additives in an arc furnace to form a fused aluminum oxide ingots, which are later crushed and sized. Fused aluminum oxide is also produced synthetically by chemically purifying. Various types of fused aluminum oxides are distinguished by the levels of chemical impurities remaining in the fused mineral. Titanium and chromium oxides are typical additives. Fused aluminum oxide is available in several variations depending on composition and processing such as white (high purity), brown or regular (titanium oxide modified), and pink (chromium oxide additions). Titanium oxide additions can toughen the abrasive and enable heat treating process, which changes brown aluminum oxide to a blue colored grain as titania precipitates form. Aluminum oxide abrasives are also produced with chemical precursors and precipitation, calcination and/or sintering processes. Calcined or platelet aluminas are used in fine grit or polishing applications. Sol-gel aluminum oxide is produced in using chemical ceramic technology, but this abrasive has very high performance and is usually referred to as ceramic abrasive grain to distinguish the grain from lower performing fused aluminum oxide. Aluminum oxide occurs naturally in the form of the mineral corundum, but the mineral is not used as a commercial abrasive except as a component of emery.