风化壳淋积型稀土矿羧酸盐浸出过程强化研究

The middle and heavy rare earth is rich in weathered crust elution-deposited rare earth ores, which is a special rare earth resources in the world. Due to the fact the middle and heavy rare earth ores is exploited from weathered crust elution-deposited rare earth ores in China, the recovery of middle and heavy rare earth is important to the world. However, the choice of lixiviant was limited in the weathered crust elution-deposited rare earth ores. As results, there are some problem existed in the exploitation of rare earth ores, such as low recovery of middle and heavy rare earth, high content of aluminum, swelling of clay minerals and the difficulty to liquid yield. Therefore, based on the previous research, the mineralogy properties of the rare earth ores from different orebody layer would be analyzed by the modern analysis and testing technology. The intensification on leaching process of middle and heavy rare earth elements and inhibit the leaching of impurities would be investigated to obtain the mechanism of reaction between rare earth ions and carboxylate ions. The mechanism on the swelling of clay minerals would be investigated as well to obtain the methods to inhibit the swelling of clay minerals. Meanwhile, the permeability rule of carboxylate leaching solution in orebody would be investigated in order to obtain better recycling of rare earth leaching solutions. According to the above research, the choice of available leaching reagent would be broadened and provide the theoretical guidance for the exploitation of rare earth ores in green and high efficiency methods.

风化壳淋积型稀土矿富含中重稀土，是各国竞相争夺的优质战略资源，这些紧缺珍贵的中重稀土主要来自我国的风化壳淋积型稀土矿。因此，提高我国风化壳淋积型稀土矿中重稀土的回收水平具有重要的现实意义。由于目前风化壳淋积型稀土矿浸矿剂选择较为单一，导致中重稀土浸出率低、杂质含量高、矿体易发生山体滑坡以及收液困难等。本项目在前期研究基础上，拟借助现代分析测试技术开展羧酸盐浸取剂强化中重稀土浸出和杂质浸出机理研究，探明稀土离子和杂质离子与羧酸根阴离子的作用机理；探寻浸出过程黏土矿物的膨胀机理，揭示羧酸盐浸取剂对黏土矿物的抑膨机制；探索羧酸盐浸取剂溶液在风化壳矿体的渗流规律，构建羧酸盐浸取剂溶液在风化矿体内的渗流模型，阐明羧酸盐浸取剂溶液在风化壳淋积型稀土矿的渗流演化机制。通过上述研究，拓宽风化壳淋积型稀土矿浸矿剂的选择，为风化壳淋积型稀土矿绿色高效低耗开采提供理论指导。

风化壳淋积型稀土矿开采存在中重稀土浸出率低、杂质含量高和山体滑坡等难题，造成宝贵的稀土资源的浪费。本项目开展风化壳淋积型稀土矿羧酸盐浸出过程强化研究。结果表明，风化壳矿体主量元素以SiO2和Al2O3为主，相对含量分别在60%~80%和10%~30%之间。江西矿风化强度大于缅甸矿，风化作用为主量元素迁移的主要影响因素。微量元素的迁移富集则较为依赖其赋存状态和氧化还原条件，受风化过程中的矿物学变化控制。稀土元素主要富集于全风化层，轻稀土和重稀土分别在风化壳上部和下部含量较高，其它微量元素含量的变化主要由其赋存状态决定。乙酸铵添加剂能够通过将铝离子留在矿物表面而不随浸出液流出来降低浸出液中的杂质铝的含量，适当的增加乙酸铵的浓度和提高浸取温度均能改善稀土和铝的浸出速率和浸出率。三种羧酸铵盐对铝抑制效果大小依次为乙酸铵＞ 柠檬酸铵＞酒石酸铵。乙酸铵浸取剂溶液的渗透速度随着水力梯度的增大呈线性增大，表明乙酸铵溶液在渗流过程中符合达西定律，且为层流状态。溶液浓度、pH以及实验温度对浸矿过程渗透性的影响，主要取决于溶液黏度与矿体表面吸附水水膜厚度。矿样粒径与孔隙度的增大，有利于加大浸取剂溶液在矿体中的渗流量，缩短渗流路径，提高渗透速度。乙酸铵浸取风化壳淋积型稀土矿的优化工艺条件为：乙酸铵质量分数为1.0 wt%，浸取温度为25℃，浸取剂pH为 7.00。通过上述研究，拓宽风化壳淋积型稀土矿浸矿剂的选择，有望通过羧酸根离子的配位作用而提高稀土浸出率，有效防止和减少风化壳淋积型稀土矿原地浸出因黏土矿物膨胀导致的山体滑坡地质灾害，为风化壳淋积型稀土矿的高效绿色低耗开采提供理论指导和技术支撑。