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采用低浓度硫酸铵溶液以柱上淋洗方式在更宽的时间范围内研究了离子吸附型稀土的浸取动力学。以1-2/3η-(1-η)~(2/3)对时间t作图所得的浸取动力学曲线由两段直线组成,证明稀土的浸出过程可以用两个阶段的内扩散控制动力学模型来描述。随着硫酸铵浓度的提高,第一阶段的浸出速率常数急剧上升,而第二阶段的浸出速率常数则先增大而后降低,但两阶段浸出所对应的速率常数差别增大。结合不同粒径颗粒样品和再吸附稀土样品浸出动力学的实验结果认为,两阶段浸出的稀土分别对应于黏土矿物表面与内层的稀土离子,其比例随矿样粒度、形成历史和硫酸铵浓度而变化。
The leaching kinetics of ion-adsorbed rare earths was studied in a wider time frame with low concentration ammonium sulfate solution on-column rinsing. The leaching kinetics curve plotted from 1 / 2ηη (1-η) ~ (2/3) to time t consists of two straight lines, and shows that the leaching process of rare earths can be controlled by two stages of internal diffusion Kinetic model to describe. With the increase of ammonium sulfate concentration, the leaching rate constant of the first stage increased sharply, while the leaching rate constant of the second stage increased first and then decreased, but the difference of the rate constants corresponding to the two stages increased. According to the experimental results of the leaching kinetics of different particle size samples and re-adsorbed rare earth samples, the two-stage leached rare earth ions correspond to the rare earth ions on the clay mineral surface and the inner layer, respectively, and their proportions vary with the particle size, formation history and ammonium sulfate concentration And change.