Kinetics of leaching process of REE from El-Missikat shear zone eastern Desert, Egypt

摘要

The leaching process of uranium-REE ore from El-Missikat in a sulfuric acid solution using hydrogen peroxide as an oxidant was investigated. The leaching condition temperature, hydrogen peroxide concentration, sulfuric acid concentration, contact time, particle size, solid-liquid ratio and agitation rate were studied. The optimum process operating parameters were ore particle size 74 μm; sulfuric acid concentration 2.5M; contact time 240 min; solid-liquid ratio 1:2; K2O2 concentration 0.5 M and agitation rate 600 rpm at temperature 25°C. The leaching efficiency of REE was about 70%, while the uranium leaching efficiency was about 95%. The experimental data were well interpreted with a shrinking core model with diffusion control through a porous product layer. The leaching process follows the kinetic model:l-3 (1-X)~(2/3) + 2 (1-X) = k_1t with an apparent activation energy of 24kJ/mole.