Abstract Common collectors for rare earth mineral (REM) flotation, which include carboxylates and hydroxamates, face problems such as being non-selective and sensitive to impurity ions. A type of ionic liquid (IL), tetraethylammonium mono-(2-ethylhexyl)2-ethylhexyl phosphonate ([N2222][EHEHP]), has been investigated previously for rare earth elements (REE) solvent extraction, and was proven selective and effective. In this work, [N2222][EHEHP] was evaluated as a collector in bastnasite (a primary REM source for REE production) flotation for the first time. The results were compared with quartz and hematite, two common gangue minerals in REM deposits. Zeta potential measurements and Fourier-transform infrared spectroscopy (FT-IR) were completed to investigate the surface chemical properties involved in the flotation of these minerals using this collector. The findings were compared to microflotation results. FT-IR and zeta potential measurements suggest adsorption of the collector’s phosphonate group onto bastnasite and hematite, likely through chemisorption; whereas for quartz, minimum microflotation recovery is likely due to no adsorption of IL on its surface. Microflotation results show higher collectability of [N2222][EHEHP] for hematite than bastnasite, the latter only showed appreciable recovery at pH 5 with elevated dosage of IL (500 g/t). To achieve better separation, a two-stage flotation scheme was designed and evaluated by bench scale flotation on a synthetic mineral mixture. The concentrates and tails were analyzed by magnetic separation, and it was found that bastnasite recovery over 90% with maximum upgrade ratio 1.7 could be achieved with elevated collector dosage.

中文翻译：

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离子液体在稀土矿物浮选中的应用研究

摘要 稀土矿物（REM）浮选常用的捕收剂，包括羧酸盐和异羟肟酸盐，面临着非选择性和对杂质离子敏感等问题。一种离子液体 (IL)，四乙基铵单-(2-乙基己基)2-乙基己基膦酸酯 ([N2222][EHEHP])，之前已经研究过用于稀土元素 (REE) 溶剂萃取，并被证明具有选择性和有效性. 在这项工作中，[N2222][EHEHP] 首次被评估为氟碳铈矿（稀土生产的主要 REM 来源）浮选中的捕收剂。将结果与 REM 矿床中的两种常见脉石矿物石英和赤铁矿进行了比较。完成了 Zeta 电位测量和傅里叶变换红外光谱 (FT-IR) 以研究使用该收集器浮选这些矿物所涉及的表面化学性质。将这些发现与微浮选结果进行了比较。FT-IR 和 zeta 电位测量表明捕收剂的膦酸酯基团吸附到氟碳铈矿和赤铁矿上，可能是通过化学吸附；而对于石英，最小的微浮选回收率可能是由于其表面没有吸附 IL。微浮选结果显示 [N2222][EHEHP] 对赤铁矿的收集能力高于氟碳铈矿，后者仅在 pH 5 和 IL 剂量增加（500 g/t）时显示出可观的回收率。为了实现更好的分离，设计了一个两阶段浮选方案，并通过对合成矿物混合物的小规模浮选进行评估。