Uranium and rare earth elements leaching characteristics from El-Sella mineralized Granite, Eastern Desert, Egypt

In this paper, a new non-conventional method for uranium leaching by thiourea (TU) was proposed. Effects of thiourea concentration, leaching time, solid/liquid ratio, stirring speed and leaching temperature for uranium leaching from the El-Sella ore were studied. The obtained optimum data for leaching of uranium by thiourea were as follow: the leaching time, the concentration of thiourea, the ratio of solid to liquid (S/L), stirring speed, the leaching temperature and particle size are 180 min, 2.24 mol/L, 1/5 g/mL, 200 rpm, 298 K and −0.25 mm respectively. The obtained uranium leaching efficiency is 89.12%. Kinetics and thermodynamic studies of the leaching process as well as the reaction mechanism between thiourea and uranium has been discussed. Results show that the predominant dissolution mechanism of uranium was diffusion controlled, exothermic nature and spontaneous reaction. REEs extraction from the uranium leached residue was studied where hydrochloric acid of 4.02 mol/L concentration solid/liquid ratio of 1/5 g/mL, for 180 min at 80°C was applied.