The book is based on the precipitation of hydrated alumina from sodium aluminate liquor, waste aluminium dross and aluminium sulfate with their ultimate conversion to activated aluminas by ageing and calcination technique. Precipitation from sodium aluminate includes different condition of boehmite (γ-AlOOH) precipitation substituting the conventional gibbsite (Al2O3-3H2O) precipitation thereby leading to an energy and cost saving process. Precipitation of hydrated alumina from waste aluminium dross is a process deliverying value added products from a waste material.Products from aluminium sulfate includes alternation of reagent addition sequences producing hydrated aluminas of different crystallinity.In all the cases the precipitates on calcination yielded different phases of alumina.