THE PROCESSING OF ALUMINO SILICATES FOR THE PURPOSE OF PRODUCINGALUMINA

Alumino silicates were once the dominant source of aluminium for the purpose of producing alumina prior to the 2nd world war.The technique was widely used, firstly in the western hemisphere in the first half of the 20th century and later by the Soviet and Chinese manufacturing plants. Since then the development of Bayer process together with the change in geopolitical landscapes has resulted in bauxite being the primary rawmaterial for aluminium production resulting in slow technical progress for the production of alumina from alumino silicates. The naturally high content of silica in the raw material makes direct use of alumino silicates problematic in the Bayer process as it will result in an uncompetitive outcome. The simplest way of processing is to sinter the alumino silicate material at elevated temperatures in the presence of limestone.However, certain chemical and physical requirements (e.g. temperature) need to be met. Several techniques have been tested on an industrial scale. The purpose of this paper is to explain these industrial techniques and to present the new options that have been developed through investigative efforts.

کلیدواژه ها:

Alumina ، Aluminosilicates ، Nepheline ، Sinter