Comparative Study of the Kinetics of Dissolution of Laterite in some Acidic Media

Olushola S. AYANDA, Folahan A. ADEKOLA, Alafara A. BABA, Olalekan S. FATOKI, Bhekumusa J. XIMBA

Department of Chemistry, Faculty of Applied Sciences, Cape Peninsula University of Technology, P.O. Box 652, Cape Town, South Africa..
Department of Chemistry, University of Ilorin, P.M.B 1515, Ilorin, Nigeria..

DOI: 10.4236/jmmce.2011.1015113                

Abstract

Studies on the kinetics of dissolution of a Nigerian lateritic soil in acids media including hydrochloric, nitric and sulphuric acids have been undertaken. The elemental and mineralogical characterization, loss of mass on ignition, moisture content and pH of the material suspension in water were determined. The effects of acid concentration, process temperature, stirring rate and particle size on the dissolution rate were investigated. Experimental results indicated that laterite dissolution was greatly influenced by hydrogen ion concentration and the leaching data fitted a diffusion model. The linear dependence of the rate constant k on 1/r_o ² supported the proposed kinetic model. Values of 60.23 kJmol^-1, 64.31 kJmol^-1 and 67.53 kJmol^-1 were obtained for the activation energies of laterite dissolution in hydrochloric, nitric and sulphuric acids respectively; and the order of reaction was approximately one with respect to each of the three acids.

Keywords

Lateritic soil, Dissolution kinetics, Hydrochloric acid, Nitric acid, Sulphuric acid.

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Aleva, G. J. J., 1994, Laterites: Concept, Geology, Morphology and Chemistry, ISRIC, Wageningen, the Netherlands, ISBN 90-6672-053-0.
[2]	Hudson, R. 2005, Using Laterite, AquaBotanic, Salem.
[3]	Schellmann, W., 1983, “Geochemical Principles of Lateritic Nickel Ore Formation.” Proceedings of the International Seminar on Laterization Processes, Sao Paulo, 119-135.
[4]	Bardossy, G., and Aleva, G. J. J., 1990, “Lateritic Bauxites.” Development in Economic Geology, 27, 624.
[5]	Olanipekun, E. O., 2000, “Kinetics of leaching laterite.” International Journal of Mineral Processing, 60, 9-14.
[6]	Aydogan, S., Aras, A., and Canbazoglu, M., 2005, “Dissolution kinetics of Sphalerite in acidic ferric chloride leaching.” Chemical Engineering Journal, 114, 67-72.
[7]	Baba, A. A., Adekola, A. F., and Bale, R. B., 2009, “Development of a combined pyro- and hydro-metallurgical route to treat spent zinc-carbon batteries.” Journal of Hazardous Materials, 171, 838-844.
[8]	Madhuchhanda, M., Devi, N. B., Rao, K. S., Rath, P. C., and Paramguru, R. K., 2000, “Oxidation of Sphalerite in Hydrochloric acid medium in the presence of manganese dioxide.” The Inst. of Min. and Metallurgy, 109, C150-C155.
[9]	Antonijevic, M. M., Jankovic, Z. D., and Dimitrijeviv, M. D., 2004, “Kinetics of Chalcopyrite dissolution by hydrogen peroxide in Sulphuric acid.” Hydrometallurgy, 71, 329-334.
[10]	Ucar, G., 2009, “Kinetics of Sphalerite dissolution by sodium chlorate in hydrochloric Acid.” Hydrometallurgy, 95, 39-43.
[11]	Stopic, S., Friedrich, B., and Fuch, R., 2003, “Kinetics of sulphuric acid leaching of the Serbian nickel laterite ore under atmospheric pressure.” Metalurgica Journal of Metallurgy, 235-244.