Ammonium sulfate has been widely applied as a leaching agent to leach rare earth from weathered crust elution-deposited rare earth ore because of its higher selectivity. However, large amount of ammonium remained on the ore body after the completion of rare earth leaching, and it was necessary to leach it from the ore body from the environmental point of view. In this work, potassium chloride was used as a leaching agent and effects of potassium chloride concentration, leaching agent pH, liquid/solid ratio and flow rate on the leaching process of ammonium were investigated in detail. It was found that potassium chloride could effectively leach the residual ammonium from rare earth tailings, and the leaching efficiency and leaching rate of residual ammonium were significantly higher than that with deionized water. Leaching agent pH almost had no effects on the leaching process of residual ammonium in the range of 2–6, and a greater impact on it at pH 8. The flow rate could effectively enhance the leaching efficiency. The optimum conditions of leaching residual ammonium were 0.06 mol/L of potassium chloride, pH 5.5–6.5 of leaching agent, 2:1 of liquid/solid ratio and 0.6 mL/min of flow rate. At these conditions, the leaching efficiency of residual ammonium was 95.78%, and the concentration of ammonium in the leachate at the final stage was 0.89 mg/L, which could meet the requirements for environment. The leaching process of ammonium in rare earth ore tailings was controlled by the inner particle diffusing according to the kinetic analysis. The reaction order was 0.117. These results suggest a promising route for the environmental remediation of weathered crust elution-deposited rare earth ore after in-situ leaching.

硫酸铵因其较高的选择性而被广泛用作从风化的硬壳洗脱沉积的稀土矿石中浸出稀土的浸出剂。但是，稀土浸出完成后，在矿体上残留有大量的铵，从环境的观点出发，有必要从矿体中进行浸出。本文以氯化钾为浸出剂，详细研究了氯化钾浓度，浸出剂pH，液/固比和流量对铵浸出过程的影响。结果表明，氯化钾可以有效地浸出稀土尾矿中的残留铵盐，其浸出效率和浸出率明显高于去离子水。pH值在2–6范围内，浸出剂的pH值几乎对残留铵的浸出过程没有影响，而在pH 8时，对浸出剂的影响更大。流速可以有效地提高浸出效率。浸出残余铵的最佳条件是：氯化钾0.06 mol / L，浸出剂pH 5.5-6.5，液/固比2：1和流速0.6 mL / min。在此条件下，残留铵的浸出效率为95.78％，最终阶段渗滤液中的铵浓度为0.89 mg / L，可以满足环境要求。根据动力学分析，通过内部颗粒扩散控制稀土矿石尾矿中铵的浸出过程。反应顺序为0.117。