Windalco Company
West Indies Alumina Company (WINDALCO), formerly Jamalcan, is a joint venture between the UC Rusal and the Government of Jamaica. UC Rusal is the majority shareholder (93% stake) and manages the joint venture. The Government of Jamaica owns the remaining 7% share.
Windalco comprises two alumina plants – Ewarton Works in St. Catherine and Kirkvine Works in Manchester.
Alumina is a fine white material similar in appearance to salt.
The Bayer process dissolves the aluminum component of bauxite ore in sodium hydroxide (caustic soda); removes impurities from the solution; and precipitates alumina tri hydrate which is then calcined to aluminum oxide.
A Bayer Process plant is principally a device for heating and cooling a large re circulating stream of caustic soda solution. Bauxite is added at the high temperature point, red mud is separated at an intermediate temperature, and alumina is precipitated at the low temperature point in the cycle.
Bauxite usually consist of two forms of alumina - a mon hydrate form Boehmite (Al2O3.H2O) and a tri hydrate form Gibbsite (Al2O3.3H2O).
Process:
1. DIGESTION OF BAUXITE
Grinding:
Pisolitic, monohydrate-grade bauxite sized to a maximum of 20mm, is ground in 10 mills (each with one compartment of rods and one of balls) to allow better solid liquid contact during digestion. Recycled caustic soda solution is added to produce a pump able slurry, and lime is introduced for phosphate control and mud conditioning.
Desilication:
The silica component of the bauxite is chemically attacked by caustic soda, causing alumina and soda losses by combining to form solid desilication products. To de silicate the slurry prior to digestion, it is heated and held at atmospheric pressure in pre-treatment tanks, reducing the build-up of scale in tanks and pipes. Most desilication products pass out with the mud waste as sodium aluminium silicate compounds.
Digestion:
The plant has three digestion units. The monohydrate slurry
Windalco comprises two alumina plants – Ewarton Works in St. Catherine and Kirkvine Works in Manchester.
Alumina is a fine white material similar in appearance to salt.
The Bayer process dissolves the aluminum component of bauxite ore in sodium hydroxide (caustic soda); removes impurities from the solution; and precipitates alumina tri hydrate which is then calcined to aluminum oxide.
A Bayer Process plant is principally a device for heating and cooling a large re circulating stream of caustic soda solution. Bauxite is added at the high temperature point, red mud is separated at an intermediate temperature, and alumina is precipitated at the low temperature point in the cycle.
Bauxite usually consist of two forms of alumina - a mon hydrate form Boehmite (Al2O3.H2O) and a tri hydrate form Gibbsite (Al2O3.3H2O).
Process:
1. DIGESTION OF BAUXITE
Grinding:
Pisolitic, monohydrate-grade bauxite sized to a maximum of 20mm, is ground in 10 mills (each with one compartment of rods and one of balls) to allow better solid liquid contact during digestion. Recycled caustic soda solution is added to produce a pump able slurry, and lime is introduced for phosphate control and mud conditioning.
Desilication:
The silica component of the bauxite is chemically attacked by caustic soda, causing alumina and soda losses by combining to form solid desilication products. To de silicate the slurry prior to digestion, it is heated and held at atmospheric pressure in pre-treatment tanks, reducing the build-up of scale in tanks and pipes. Most desilication products pass out with the mud waste as sodium aluminium silicate compounds.
Digestion:
The plant has three digestion units. The monohydrate slurry