The seperation of the alumina from the impurities in the baurite ore is usually accomplished by bayer process. The bauxite ore is leachedwith caustic soda (NaOH) to produce soluble sodium Aluminate (NaAlO2) leaving the impurities in the insoluble residue. The aluminate solution is then decomposed producing Al(OH)3 which is calcined to produced Al2O3 so, leaching is carried ot by caustic soda