Investigating the use of an ionic liquid for rare earth mineral flotation☆

• 作 者: R.Li C.Marion E.R.L.Espiritu R.Multani Xiaoqi Sun K.E.Waters
• 机 构: Department of Mining and Materials Engineering,McGill University,3610 Rue University,Montr(e)al,Qu(e
• 出 处: 稀土学报（英文版）
• 发表日期: 2021年7期
• 关键词: Ionic liquid Rare earth Bastn(a)site Flotation FT-IR Zeta potential

Common collectors for rare earth mineral (REM) flotation, which include carboxylates and hydrox-amates, 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 to be selective and effective. In this work, [N2222][EHEHP] was evaluated as a collector in bastn(a)site (a primary REM source for REE production) flotation for the first time. The results were compared with quartz and he-matite, 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 with microflotation results. FT-IR and zeta potential measurements suggest adsorption of the collector's phosphonate group onto bastn(a)site and hematite, likely through chemisorption;whereas for quartz, the 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 bastn(a)site, the latter only shows appre-ciable 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 is found that bastn(a)site recovery over 90％ with maximum upgrade ratio 1.7 can be achieved with elevated collector dosage.