Desilication studies of diasporic bauxite by thermochemical treatment

In this paper, desilication experiments on calcined diasporic bauxite by thermochemical treatment is investigated. For this purpose, calcined samples at specific temperature, were leached with caustic soda at 95°C. The experiments is conducted in two sections: optimizing calcination conditions and determination of leaching parameters. Calcination experiments revealed that the optimum calcination temperature and time are 1000°C and 60 minute respectively. By optimizing these parameters, 42.22% of bauxite silica content is extracted and module ratio (ratio of Al2O3 to SiO2) reaches to 2.94. According to leaching experiments the optimum leaching parameters is determined as: leaching time 120 minutes, caustic soda concentration 200 g/L, pulp dilution 4 and particle size below 210 µm. As a result, silica extraction percentage and module ratio increase to 50.92 and 3.5 respectively.