Effect of αk on aluminium trihydroxide crystallization from sodium aluminate soluntion under Ultrasound

摘要

The crystallization with ultrasound intensification of aluminium trihydroxide from seeded sodium aluminate solution is investigated under various αk (the molecule ratio of Na2O/Al2O3). The results indicate that ultrasound can enhance precipitation ratio of seeded sodium aluminate solution. However the increase of αk is not useful to improvement of the precipitation under ultrasound. For example, when the αk is 1.45、 2.0 and 2.5, the precipitation ratio increase 2.5%、2.0% and 0.9%, respectively under ultrasound. The mechanism of enhancement on precipitation of alumina hydrate is acoustic cavitations that enhance or alter reactions process of aluminate ions, Al(OH)-4. The mass percentage of <45μm of precipitation production with the initial αk at 2.0, which is biggest, is increased by 4.3 % under ultrasound.