Influence of oxalic acid on the agglomeration process and total soda content in precipitated Al(OH)_3

摘要

Decomposition of caustic soda solutions is an important part of Bayer process for alumina production. The physico-chemical properties of precipitated Al(OH)_3 are dependent on several processes that take place simultaneously during the decomposition process and they are: nucleation, agglomeration and Al(OH)_3 crystals. An important industrial requirement is increase of Al(OH)_3 crystal grain size, and hence agglomeration and growth of Al(OH)_3 crystals become important processes and they enable increase of particle size. The influence of oxalic acid concentration on the agglomeration process and total soda content in precipitated Al(OH)_3 at different temperatures and caustic soda concentrations has been investigated. The results have shown that the agglomeration process is increased with increase of temperature and decrease of caustic soda concentration. Total soda content in precipitated Al(OH)_3 is changed in the same way. Besides, agglomeration process of Al(OH)_3 particles is favored in the presence of oxalic acid.