离子型稀土矿无铵绿色浸矿剂探索研究

Study on green and ammonium-free leaching agent for ion-absorbed rare earth ore

本文对南方离子型稀土矿开展了新型无铵绿色环保浸矿剂探索试验,研究了浸矿剂浓度、液固比和pH值对硫酸铵、硫酸镁和SAK(一种含K和Al的复盐)3种浸矿剂浸矿的影响,并综合比较了该3种浸矿剂的浸矿效果。结果表明,RE和Fe、Si、Al、Ca杂质元素浸出率随着浸矿剂浓度和液固比增加呈现先增后趋于平缓趋势,随着pH值增大而呈现递减趋势;在浸矿剂浓度2%、液固比0.6∶1、硫酸铵和硫酸镁pH值5.0、SAK pH值3.0的条件下,进行稀土矿中金属浸出试验,Al浸出率大小顺序为硫酸铵>硫酸镁>SAK;Fe、Si和Ca则为SAK>硫酸铵>硫酸镁;相比硫酸镁,硫酸铵和SAK浸矿速度较大,洗水用量较少。从无氨氮绿色环保、浸矿效果方面考虑,确定SAK为新型浸矿剂,最优浸矿工艺参数为浸矿剂浓度2%,液固比0.6∶1,pH值3.0,此条件下稀土浸出率为96.93%,Al浸出率为13.78%。

In this work,the green and ammonium-free leaching agents for ion-absorbed rare earth ore in southern China were explored.The effects of leaching agent concentration,liquid-solid ratio and pH value on rare earth leaching by ammonium sulfate,magnesium sulfate and SAK(a complex salt of aluminum and potassium)were investigated,and the leaching effects were compared among these three leaching agents.The results showed that the leaching efficiency of rare earth and impurities including Fe,Si,Al and Ca increased and then became flat with the increase of the leaching agent concentration or liquid-solid ratio,and decreased with the increase of the pH value.Under the leaching conditions(leaching agent concentration of 2%,liquid-solid ratio of 0.6∶1,pH value of 5.0 for ammonium sulfate and magnesium sulfate,and pH value of 3.0 for SAK).The leaching efficiency of impurity Al followed the order of ammonium sulfate>magnesium sulfate>SAK,and the leaching efficiency of Fe,Si,and Ca was in the order of SAK>ammonium sulfate>magnesium sulfate.At the same time,the leaching velocity of ammonium sulfate and SAK were significantly higher than that of magnesium sulfate,the volume of washing water dropped sharply comparing with magnesium sulfate.And SAK was determined as the new kind of leaching agent based on environmental protection and leaching effect.The optimal leaching behavior with SAK can be obtained at the leaching agent concentration of 2%,liquid-solid ratio of 0.6∶1,as well as pH value of 3.0,with corresponding leaching efficiency of RE and impurity Al of 96.93%and 13.78%,respectively.