The novel strategy of ion-adsorbed minerals leaching based on high abundance yttrium for resources, environment and efficiency

Yttrium (Y) is the most abundant RE element in ion-adsorbed RE minerals. To realize the balanced and sustainable application of RE resources, some Y salts (YCl3, Y2(SO4)3 and Y(NO3)3) were used instead of (NH4)2SO4 and MgSO4 as leachants to recover RE from ion-adsorbed RE minerals in this study. During the soak leaching process, when the cation concentration of the leachant is 0.05 mol/L, the leaching efficiency decreases from 59% to 37% in the order of Y3+>Mg2+>NH4+. The leaching rate increases with the increase of the concentration of the leachant. In the column leaching, at the concentration of 0.01 mol/L leachant, the final leaching rate of YCl3 for non-Y RE is 55.63%, while the leaching rate of Mg2SO4 is only 30.78%. The effects of concentration and pH value of the leachant on the column leaching were studied. The optimum conditions were determined as follows: the solid-liquid ratio was 1:1, the pH value was 4, the concentration of YCl3 was 0.03 mol/L, and the maximum leaching efficiency of non-Y RE was 100%. The absolute zeta potential of tailings after YCl3 leaching is located in a strong agglomeration area, which is helpful to avoid landslides in goaf areas. This study shows that YCl3 has excellent potential to leach RE instead of (NH4)2SO4. It provides a new choice to solve the environmental problems from ammonia-nitrogen pollution caused by industrial (NH4)2SO4 leaching. The leaching strategy of Y is helpful to protect RE resources, reduce environmental pollution and improve RE separation efficiency.