Chemical-kinetic study of GaAs chlorination at low temperatures

F. TÚNEZ, J. A. GONZÁLEZ, O. QUIROGA AND M. DEL C. RUIZ

Advances in Cleaner Technologies for the Mining and Metallurgical Industry

Editors: M. Sánchez, A. Valenzuela, E. Chaparro, A. Reghezza and J. Álvarez, University of Conception

Lugar: Chile; Año: 2008; p. 81 - 94

The compounds of gallium, GaAs and GaP, are widely used in the electronic industry. The gallium is found in low concentrations in the earth’s crust and due to its growing demand and low production from natural resources, its recovery from electronic wastes could be a suitable way to increase its availability. The recovery of Ga from GaAs compuest using chlorination is an economical and efficient technique. The aim of this study is to provide data to elucidate the mechanism and kinetics of the chlorination reaction of GaAs to apply the results to recover Ga. Results of kinetic study of the chlorination of GaAs using pure chlorine gas as a chlorinating agent and nitrogen as gas for dilution and purging are shown. The range of temperatures studied was between -30°C and 200°C and the partial pressure of chlorine varied between 0.2 and 1 atm. Experimental data obtained were processed with the software MODELADO "Software for Kinetic Treatment and Fluid-Solid Reactive Transformations", which correlates the data with different models for kinetic reactions fluid-solid reactive. It was found that the best correlation is obtained with the model 19 of the mentioned software. This model was developed based on a sequential nucleation mechanism in which the formation of nuclei occurs in two stages and the growth of nuclei is in two dimensions.