Alumina Refinery Process Flow Diagram

alumina refinery process flow diagram and process description
Alumina refinery process flow diagram
Bauxite is used as raw material for production of alumina; the composition of bauxite contains about 50% of aluminum oxide and about 5% silica. The process involves crushing of bauxite to 100- mesh and dissolved in Bayer digesters with the help of caustic soda and lime in the presence of hot water and steam under sufficient pressure by which sodium aluminate is formed, silica forms as precipitate by forming sodium aluminum silicate.

Drum filters separates the red mud from the solution and by cooling the filtered solution sodium aluminate form a precipitate of aluminum hydroxide. This residue is washed and filtered in rotary drum filter. By using rotary calciner which operates at 9800C the aluminum hydroxide is calcined and cooled in rotary cooler and shipped. Filtrate of caustic soda is concentrated and reused in the process. Most of the red mud is used in batch process to collect the alumina content at once.

There are other famous processes which are Mexican process also known as U.G process. A French Pechiney-Ugine Kuhlmann process, by using aluminum chloride subjecting to continuous electrolysis.