Alumina production. View of part of a treatment plant where recently-mined bauxites are converted into alumina for export. Bauxite is a family of aluminium ores, mainly gibbsite and boehmite. The alumina is produced by the Bayer process. The bauxite is reacted under pressure with a caustic solution to form sodium aluminate. The solution is hot-filtered and cooled, then agitated with 'seed' crystals of aluminium hydrate. The resulting hydrate 'cake' is then dried at 1100 Celsius to yield alumina (aluminium III oxide). The alumina may then be exported, mainly to electrolysis plants to extract aluminium metal. This plant is at Discovery Bay, Jamaica.