Hydrometallurgical processing of egyptian bauxite

A bauxite ore from Um Bogma, Southwestern Sinai, Egypt was mineralogically characterized. It contains 70% gibbsite, 13.2% quartz and 11.0% kaolinite. Beneficiation of the ore reduced the quartz content to 2.4%. Hydrometallurgical processing of the beneficiated gibbsitic bauxite was performed by hot leaching with sodium carbonate and lime in an attritor. Aluminium was converted to soluble sodium aluminate low in SiO2 (<0.1%) and the recovery was over 95% for a short leaching duration of 30 minutes at 90 °C. The residue was essentially composed of calcium silicate.