Kinetics of leaching of 20CaO·13Al2O3·3MgO·3SiO2

Abstract

The leaching kinetics of 20CaO·13Al2O3·3MgO·3SiO2 (Q phase) was studied in this paper. The effects of agitation speed, leaching temperature, concentration of sodium carbonate, particle size and liquid–solid ratio on alumina leaching ratio of Q phase were investigated. The results indicate that the agitation speed did not influence alumina leaching ratio when it was higher than 400 r min−1, and the effect of liquid film diffusion on the leaching process was eliminated. The alumina leaching ratio would not increase by changing the liquid–solid ratio, when the concentration of sodium carbonate was excessive. The leaching process of Q phase was better as both the temperature and the concentration of sodium carbonate were higher and the particle size was smaller. The effect of concentration of sodium carbonate on alumina leaching ratio was not obvious. The leaching kinetics followed the shrinking unreacted core model, the reaction order of leaching process of Q phase was 0.47, and it can be described by surface chemical reaction. The activation energy was 41.63 ± 10 kJ mol−1, and the frequency factor was 1.472 × 103.