The investigation of efficient conditions for alumina production from diasporic bauxites

Abstract

The main objective of this study was to investigate the leach conditions of diasporic bauxites in the region of Mugla-Milas for alumina production. The chemical composition was 57.91% Al2O3,, 21.33% Fe2O3, 3.84% SiO2, 2.20% TiO2, 2.10% CaO, 1.02% FeS2, 1.65% CO2, and 0.52% other. The effects of alkaline (CaO and/or Na2CO3) additives, precalcination temperature, calcination time, leaching time, solution concentration, liquid/bauxite ratio and particle size on the efficiency of alumina and silica dissolution were investigated. The optimum conditions of the process were the addition of alkaline in 0.5 mole fraction, 900 degreesC precalcination temperature, 2 hours of calcination time, 3 hours of leaching time, 1.5 molar Na2O of caustic concentration and liquid/bauxite ratio of 30 at the boiling temperature of leach solution under continuous stirring. Although the highest extraction efficiency of Al2O3 was found to be 81.77% with precalcination at 1200 degreesC, 900 degreesC was preferred as an optimum calcination temperature.