Experimental Study On Enhanced Uranium Leaching From Low-grade Uranium Ore By Electric-assisted Method

Uranium is extremely difficult recovered from low grade tailings because of low content of uranium,severe damage of gangue and a large number of insoluble U（Ⅳ）in ore.This study proposed the process that electric-assisted leaching uranium in low-grade uranium tailings.Its basic principle is based on iron as the anode,inert graphite as the cathode.With the dissolute of anode of iron,which provide oxidant Fe（III）convert the U（Ⅳ）to U（Ⅵ）under the action of electric field.At the same time,electric field promote the migration of impurity ions to the electrodes and reduce the precipitation of impurity ions formed in mineral particles surface of the package.This paper focus on the influence of electric-assisted leaching process parameters on uranium leaching ratio.Through find out the change of mineralogy properties in leaching process,the influence of electric-assisted leaching mechanism on uranium leaching is investigated.The dynamics equation of electric-assisted leaching is built,the main results are as follows:The results show that the leaching ratio of uranium can be significantly improved by electric-assisted leaching,and the main factors affecting leaching ratio of uranium are electrode material,leaching temperature and sulfuric acid concentration.Under optimal conditions,the electric-assisted leaching ratio of uranium higher than direct acid leaching 38%.Under the conventional acid leaching of uranium ore phase composition and morphology structure did not change obviously,and electric-assisted leaching process reduce the part of the crystallinity of gangue minerals,promote the formation of mineral particle surface pore,improve the dissociation ratio of uranium.Low grade uranium leaching dynamics research results show that the direct acid leaching and electric-assisted leaching reaction process are controlled by external diffusion,apparent activation energy of 12.839 k J/mol,and 12.88706 k J/mol,respectively.Leaching kinetics equation are 1-^2/3a-（1-α）^2/3=Kdt= K0（H₂SO₄）^-2.39885（S/L）^-2.47553 e^-1544.29/T t and 1-^2/3a-（1-α）^2/3=Kdt= k0（H₂SO₄）^0.6398（S/L）^-13.69754 e^-1549.95558/T t,respectively.It shows that electric-assisted leaching apparent activation energy is higher than conventional acid leaching.Electric-assisted leaching ratio and the reaction ratio are better than the conventional acid leaching conditions.This study can be used for reference for noble metal leaching process of low-grade ore or tailings and improving the leaching ratio of precious metals.