Influence of the Alkali-promoted phase transformation in monazite for selective recovery of rare-oxides using deep eutectic solvents
Influence of the Alkali-promoted phase transformation in monazite for selective recovery of rare-oxides using deep eutectic solvents
复制标题
独居石中碱促进相变对使用低共熔溶剂选择性回收稀有氧化物的影响
DOI：
10.1016/j.mineng.2022.107564
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发表时间：
2022
影响因子：
4.8
通讯作者：
Sanchez-Segado S
中科院分区：
文献类型：
--
作者：
Sanchez-Segado S
研究了独居石在1 0 0 0℃、Na2 CO3摩尔比为1.0~5.0的条件下，在1 0 0 0℃、2 h的高温相变过程中发生的物理化学变化。当独居石：碱比为2时，稀土磷酸盐的形成占主导地位，但当碱比低于2时，独居石以Na3PO4和Ce1-xLnxO2-x/2固溶体的形式发生脱磷，为稀土氧化物从矿物基质中分离提供了独特的选择性。用循环伏安法研究了CeO2、La2 O3、Nd2 O3和Pr2/Pr2 O3在深度共熔溶剂Etherine(氯化胆碱和乙二醇比为1：2)中的循环伏安行为，证明了这些氧化物的电化学活性。纯氧化物和水浸独居石按1：1的比例高温反应后，在0.1mol/L葡萄糖溶液中进行了电溶解实验，纯Nd2 O3的优先溶解度为2 3.85%，而CeO2、La2 O3和PrO2/Pr2 O3的纯氧化物则不溶.我们还观察到，由于Ce1-xLnxO2-x/2固溶体的惰性行为，水浸出的独居石不可能电溶解。避免高温过程中的氧化，将产生一种利用氧化物的阶段性电化学制取稀土氧化物的进一步选择性的方法。
The physico-chemical changes occurring during the high-temperature phase transformation of monazite in the presence of Na 2 CO 3 at 1000° C for 2 h duration at monazite: Na 2 CO 3 ratios between 1.0 and 5.0, were investigated. The formation of sodium lanthanide phosphates was prevalent above a monazite: alkali ratio of 2, however, below this ratio, the dephosphorization of monazite as Na 3 PO 4 and Ce 1-x Ln x O 2-x/2 solid solutions occur offering unique selectivity for rare-earth oxide separation from the mineral matrix. Cyclic voltammetry of pure CeO 2, La 2 O 3, Nd 2 O 3, and PrO 2/Pr 2 O 3 was carried out in the deep eutectic solvent Ethaline (1: 2 mixture of choline chloride and ethylene glycol) proving the electrochemical activity of these oxides. Electrodissolution of pure oxides and water-leached monazite after high-temperature reaction with a ratio of 1: 1 was carried out in a 0.1 mol/L glucose solution in Ethaline showing a preferential solubility of 23.85% for pure Nd 2 O 3. In contrast, pure oxides of CeO 2, La 2 O 3 and PrO 2/Pr 2 O 3 were found to be insoluble. We also observed that electrodissolution of the water leached monazite was not possible because of the inert behaviour of Ce 1-x Ln x O 2-x/2 solid solutions. Avoiding cerium oxidation during the high-temperature process will lead to a method for further selectivity for rare-earth oxide processing using staged electro-chemical winning of oxides.