Kinetics Study of Alumina Leaching from Ogbunike Clay Using Hydrochloric Acid

Abstract

The kinetics study of alumina leaching from ogbunike clay was carried out using a solution of hydrochloric acid (HCl) for alumina dissolution. Variations in process parameters such as calcination temperature, leaching temperature, acid concentration, particle size, and solid-to-liquid ratio were considered for the leaching of alumina. The shrinking core model was used to analyze the experimental data. Alumina removal is feasible with 24.035% extractable alumina, and this can improve the economic value of ogbunike clay, which can be an alternative raw material in Nigeria’s aluminum industries. According to the data the dissolution rate increases with increasing calcination temperature, leaching temperature and acid concentration and decreasing particle size and solid-to-liquid ratio. The statistical and graphical analysis revealed that the dissolution followed the product layer diffusion-controlled semi-empirical kinetic model. The activation energy was calculated to be 18.36 kJ/mol for HCl. The optimum conditions for the dissolution of the alumina in HCI include activation temperature of 700 ⁰C for 60 minutes, leaching temperature of 90 ⁰C, HCl concentration of 3 M, particle size of 75 µm, and the solid-liquid ratio of 0.2 g/ml yielding the alumina dissolution rate of 84.72%. The kinetic data can be used to construct large-scale manufacturing equipment.