Aluminium hydroxide or alumina tri hydrate (ATH) is the hydrated oxide of aluminium. Alumina hydrate is separated from bauxite ore using the Bayer process, with average particle size ranging from 80-100 micron. The block crystals of alumina hydrate impart good chemical reactivity. Alumina hydrate can react with a base as well as an acid, and finds use in many applications as raw material.