Refining Process
The aluminum industry relies on the Bayer process to produce Alumina from Bauxite. Bauxite is crushed, ground and digested in caustic soda at high pressure and temperature. The resulting liquor contains a solution of sodium aluminate and un-dissolved Bauxite residues containing iron, silicon, and titanium. These residues, known as “red mud”, settle gradually to the bottom of the settling tank and are filtered and removed.

The clear sodium aluminate solution, which is called aluminate liquor, is pumped into a series of huge tanks called precipitators. Fine particles of alumina are added to seed the precipitation of pure Alumina particles as the liquor cools.

Concentration of the solid particles increases, which are then removed, filtered and washed, and passed through a rotary or fluidized calciner at 1100°C to drive off the chemically combined water. The result is a white powder, pure Alumina.