Improved Method for the production of Alumina from nepheline ores

摘要

In nepheline raw material processing to alumina, raw material grinding during charge mixt. prepn. takes place simultaneously with charge mixt. drying, using sinter-step waste gases. During sintering, the charge mixt. is heated to 900-950 deg.C in 1-3 min. while in suspension. The desilicising and causticising sludges, formed during the subsequent hydrochemical treatment of the sinter material, are returned to sinter-step. The process can be applied to nepheline contg. 20-30 wt. % alumina. Waste, with the exception of recycle material, is used in cement, soda and potash prodn. Fuel consumption during sintering is reduced, e.g. by 0.425 t/t alumina. Output is increased, e.g. 4 times. In first, low temp. quick sinter-step, decarbonising achieved can be 100%.