Research on mechanically activated digestion performance of diasporic bauxite and kinetics

Abstract

This paper proposes a “mechanical activation-homogeneous digestion” technology as a strengthening method for diasporic bauxite digestion process of alumina production. Effects of digestion temperature, digestion time and mechanical activation speed on digestion performance of diasporic bauxite were investigated by using “homogeneous digestion” equipment, and the digestion kinetics of diasporic bauxite was studied as well. The results indicate that the mechanical activation can greatly improve the digestion performance of diasporic bauxite, digest mine with larger particle size. The optimal mechanically activated digestion temperature is 20°C lower than that of direct digestion. The relative digestion rate of alumina goes up to above 97% when digested at 245°C for 60 minutes with a mechanical activation speed of 80rpm. The apparent activation energy of mechanically activated digestion is 57.30kJ/mol, 21.09kJ/mol lower than the direct digestion. The kinetic equation of mechanically activated digestion is (1-η)-1/3-1=1.5532×10-4exp(4.764×105/T)t.