Bayer Process: Refining Bauxite into Alumina
The Bayer process route from bauxite to alumina: caustic digestion, red mud separation, precipitation and calcination, and how each step sets the cargo's shipping properties.
The Bayer process is the industrial route from bauxite ore to alumina, and it is the reason every alumina cargo has the physical properties its IMSBC schedule records. Bauxite is digested in hot caustic soda, which dissolves the aluminum content as sodium aluminate while most other minerals remain solid and are removed as red mud. The clarified liquor is cooled and seeded so that aluminum hydroxide precipitates, and that hydroxide is calcined to drive off the chemically bound water.
The full article will cover the chemistry of each stage, the energy and caustic balances, red mud disposal and its environmental record, the difference between metallurgical and chemical grade output, and the process controls that set particle size distribution, surface area and soda content. Those last three are what a ship actually feels: they govern dust generation, moisture adsorption and the receiver’s impurity specification.
It will also cover the geography, since refineries are sited near bauxite mines or at coastal locations that can take ore in and ship alumina out, which is what creates the seaborne alumina trade in the first place.