Bayer Process

This is a process for the production of Alumina, which was patented by Karl Josef Bayer in Austria in 1888. It involves the digestion of crushed Bauxite in sodium Hydroxide solution at high temperatures (~240 ^oC).

Most of the Alumina will dissolve, leaving a "red mud", which is removed by filtration.

The remaining product is then decomposed by reversing the reaction, by cooling and adding the trihydrate, Al₂O₃.3H₂O. This gives:-

2NaAlO₂ + 2H₂O -> 2NaOH + Al₂O₃.3H₂O

This is then heated to drive off the water of crystallization, which produces Alumina.