Question

During the concentration process of bauxite,
Why is $Al(OH{)}_3$ added in small quantity and diluted with water to sodium aluminate solution ?

Answer 1

When $Al(OH{)}_3$ is added in small quantity and diluted with water to sodium aluminate solution , the whole aluminium in the solution gets precipitated as $Al(OH{)}_3$. The $Al(OH{)}_3$ precipitate is separated from the solution. Then it is washed and heated strongly to form pure $A{l}_2{O}_3$ or alumina.