磷酸溶液中稀土元素的溶解行为

摘要

In order to provide practical fundamental data for rare-earth elements (REEs) recovery from phosphoric acid and to better understand REEs behavior during the phosphoric acid evaporation process, the solubilities of REEs in phosphoric acid with various concentrations of phosphorus at different temperatures were measured. A simple linear model between REEs solubility and phosphoric acid concentration is built and the experimental data are found to fit it very well (R2>0.94). Hydrogen-ion concentration is found to be the predominant factor controlling the solubility of REEs in phosphoric acid. In addition, the solubility of REEs in phosphoric acid is found to sharply decrease with increasing temperature, which can be attributed to the increase of the Gibbs energy of the REEPO4 dissolution reaction or the restraint of the disassociation of phosphoric acid molecules owing to the elevated temperature.%为了建立磷酸溶液中稀土回收工艺性基础数据和更好地了解磷酸蒸发浓缩过程中的稀土行为,测定不同温度条件下不同磷浓度的磷酸溶液中的稀土溶解度.建立关于磷酸溶液中稀土溶解度与磷浓度之间简单线性模型,该模型与实验测定的磷酸溶液中稀土溶解度具有较高的契合度(R2>0.94).磷酸溶液中稀土溶解度的控制性影响因素为溶液中氢离子浓度.此外,升温能使磷酸溶液中稀土溶解度迅速下降,这主要是因为升温导致磷酸稀土的溶解反应吉布斯自由能升高,同时,升温还抑制磷酸分子的电离.