乙酸铵助浸风化壳淋积型稀土矿过程研究

Leaching process of weathered crust elution-deposited rare earth ore assisted by ammonium acetate

针对目前风化壳淋积型稀土矿浸出过程中稀土浸出率低、中重稀土浸出效果差、稀土浸出液中杂质铝含量高以及浸取过程中黏土矿物膨胀率高等系列问题,采用0.20 mol/L硫酸铵为浸取剂,乙酸铵为助浸剂,探究乙酸铵对稀土浸出过程及黏土矿物膨胀性能的协同作用。结果表明:乙酸铵最佳助浸浓度为0.04 mol/L,此时稀土浸出率提高了4.81%,杂质铝的浸出率减小了48.66%,稀土总浓度提高了45.18μg/g,其中轻稀土浓度减小了27.26μg/g,中重稀土增加了72.44μg/g,表明乙酸铵强化了中重稀土的浸出。同时,乙酸铵浓度为0.04 mol/L时黏土矿物膨胀率为2.951%,相对硫酸铵作为单一浸取剂时膨胀率降低了1.298%。随乙酸铵助浸剂浓度的变化,稀土浸出率与Zeta电位变化成正比,黏土矿物膨胀率与Zeta电位变化呈反比,当乙酸铵浓度为0.04 mol/L时,黏土矿物表面Zeta电位为-18.26 mV。对于淋浸尾矿,添加乙酸铵后的尾矿则有较好的防膨性能,膨胀率仅为2.054%。本研究对风化壳淋积型稀土矿的稀土原地高效浸出提供了一定的有益指导。

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 45.18μg/g.The concentration of light rare earth decreases by 27.26μg/g,and that of medium and heavy rare earth increases by 72.44μg/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.