Leaching process of weathered crust elution-deposited rare earth ore assisted by ammonium acetate
In light of a series of issues such as low leaching efficiency of rare earth,poor leaching effect of medium and heavy rare earth,high impurity aluminum in rare earth leaching solution,and high clay mineral swelling ratio in the current leaching process of weathered crust elution-deposited rare earth ore,we used 0.20 mol/L ammonium sulfate as the leaching agent and ammonium acetate as the assisting leaching agent to explore the synergy of ammonium acetate on the rare earth leaching process and the swelling properties of clay minerals.The results show that the optimal assisted leaching concentration of ammonium acetate is 0.04 mol/L,under which the leaching efficiency of rare earth increases by 4.81%,the leaching efficiency of impurity aluminum decreases by 48.66%,and the total concentration of rare earth increases by 45.18 μg/g.The concentration of light rare earth decreases by 27.26 μg/g,and that of medium and heavy rare earth increases by 72.44 μg/g,indicating that ammonium acetate enhances the leaching of medium and heavy rare earth.Meanwhile,the swelling ratio of clay mineral is 2.951%,and the expansion rate is reduced by 1.298%compared with that of ammonium sulfate as a single leaching agent.With the change of the concentration of ammonium acetate,the leaching efficiency of rare earth is positively proportional to the change of Zeta potential,and the swelling ratio of clay minerals is inversely proportional to the change of Zeta potential.When the concentration of ammonium acetate is 0.04 mol/L,the Zeta potential on the surface of clay minerals is-18.26 mV.For the leached tailings,the leached tailings with ammonium acetate added have better anti-swelling performance,and the swelling ratio is only 2.054%.This study provides some beneficial guidance for the efficient in-situ leaching of rare earth from weathered crust elution-deposited rare earth ores.
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