Process for preparing aluminium hydroxide with bayerite crystalline structure

摘要

When transforming amorphous hydrated aluminium oxide to aluminium hydroxide with bayerite crystalline structure the amorphous hydrated aluminium oxide is freed from electrolytes by washing with water. Subsequently it is suspended in water and ammonia. Molecular ratio of NHi3 : Al in the suspension ranges from 0.2 to 0.6 : 1. The resulting suspension is the subjected to ripening at a temperature ranging from 10 to 40 degC for a period of 1 to 21 days. A preferable process of this transformation consists in that the hydrated aluminium oxide is mixed in water and ammonia to form non-settling particles. Another preferable process consists in that prior ripening phase, inoculation bayerite crystals are added to the aluminium hydroxide suspension.