Alumina products as commodity raw materials. Major uses are sintered and fused transformation products and refractory commodities, specifically:
- Tabular alumina and spinel
- Fused alumina
- Ceramic fibres
- Fused cast refractories
- Calcium aluminate cements
Aluminas with intermediate to relatively high specific surface areas (BET 3- 75m²/g) with alpha alumina contents varying between 20% and 95%.These are produced by controlled rotary calcination of aluminium trihydroxide.
Coarse alumina hydrate
Aluminium trihydroxide (ATH) is produced by the Bayer Process in Gardanne. These ATH grades are used for the production of a variety of aluminium salts and in glass production.
Ground calcined alumina
These aluminas are ground in continuous ball-mills or air-jet mills to median particle sizes (d50) 3, 4, 5 or 6 µm.
Hard calcined alumina
These aluminas have low specific surface area (BET < 1m²/g) and are almost entirely alpha alumina. Standard soda content is 3000-4000 ppm and intermediate soda content is 2000-3000 ppm. Hard calcined aluminas are produced in rotary kilns.
Low soda alumina
This alumina has very low soda content: between 300 and 500ppm. Carefully controlling calcination using the proprietary Reynolds process also allows a wide range of primary crystal size to be offered.