Multistage Leaching Kinetics of Chromite in HCl-Na2CrO4 System.

The multi-stage leaching of chromite in HCl-Na₂CrO₄, system has been studied, and the leaching kinetics of main metal elements in chromite has been discussed. The results show that under the optimal conditions of particle size of 45~75 µm, oxidizing agent Na₂CrO₄, dosage of 0.6 times of theoretical dosage, reaction time of 5 h, reaction temperature of 453.15 K, ball to material mass ratio of 1/1, stirring speed of 30 r/min, liquid volume to solid mass ratio of 4 mL/1 g, the three-stage cyclic leaching is carried out, the leaching rates of Cr, Fe, Al and Mg can reach 91.98%, 94.54%, 76.62% and 78.03 %, respectively. The acid leaching reaction of chromite is controlled by interfacial chemical reaction. The apparent activation energies of Cr, Fe, Al and Mg are 45.80, 40.43, 42.08 and 43.54 kJ/mol, respectively. In the range of 373.15~473.15 K, and the leaching effect is good. [ABSTRACT FROM AUTHOR]