Bayer_process
WEBBauxite, the most important ore of aluminium, contains only 3054% alumina, Al 2 O 3, the rest being a mixture of silica, various iron oxides, and titanium alumina must be purified before it can be refined to aluminium metal. In the Bayer process, bauxite is washed with a hot solution of sodium hydroxide, NaOH, at 175°C (called digestion).