Assessment of Amagunze microcline for alumina recovery in nitric acid and hydrogen peroxide solutions and kinetic study

Abstract

ABSTRACT The leaching of alumina from Amagunze microcline in nitric acid/hydrogen peroxide binary solution was examined in this study. The parameters considered in the study include leaching temperature, hydrogen peroxide concentration, solid/liquid (S/L) ratio and particle size. The leaching rate of alumina increased as the leaching temperature and hydrogen peroxide concentration were increased, and decreased with an increase in S/L ratio and particle size. The experimental data fitted into the chemical reaction model, which was also established as the rate-controlling step. Activation energy was estimated as 16.04 kJ/mol while the Arrhenius constant was estimated as 0.823 s−1. About 88.3 % alumina leaching rate was recorded at the optimum conditions. The overall reaction rate was estimated as 0.3051 s−1. Post-leaching analysis of the residues showed that zircon, illite, quartz and microcline were present. Hence, microcline proved to be a viable source for alumina. The kinetic models used were also sufficient for analyzing the experimental data.