Effect of αk on Aluminium Trihydroxide Crystallization from Sodium Aluminate Soluntion under Ultrasound

The ultrasound intensification crystallization process of aluminium trihydroxide from seeded sodium aluminate solution is investigated with various αk(the molecule ratio of Na2O/Al2O3). The experiment results indicate that ultrasound intensification can enhance precipitation ratio of seeded sodium aluminate solution, while large αkdoes not good to improvement of the precipitation under ultrasound. When αkis 1.45, 2.0 and 2.5, the precipitation ratio increase 2.5%, 2.0% and 0.9%, respectively under ultrasound intensification. 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 precipitation production grain size <45μm is increased by 4.3 % under ultrasound intensification with initial αkat 2.0, which is the biggest. Key words: ultrasound; sodium aluminate solution; precipitation; aluminium trihydroxide