pre-desilification process to remove bauxite kaolin as part of a bayer process, and, bayer process plant

摘要

PREDESSILICATION PROCESS TO REMOVE BAUXITE KAOLIN AS PART OF A BAYER PROCESS, AND BAYER PROCESS PLANT In the Bayer process for alumina production, problems are caused by the dissolution of silica in caustic liquor. This silica arises from the presence of kaolin in bauxite. A process for removing this kaolin comprises contacting bauxite with sodium hydroxide solution to form a mixture and subjecting the mixture to intense ultrasonic irradiation to cause cavitation; This can be performed at temperatures below 100 ° C. This improves both kaolin dissolution and sodium aluminosilicate precipitation. Remaining silica in spent Bayer liquor solution (after digestion and then gibbsite precipitation) can be removed by a similar ultrasonic irradiation treatment to precipitate it before forming scale on the heat exchangers.