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Qian Cheng, Zerui Lei, Guangjun Mei, and Jianhua Chen, Impact of ethanol on the flotation efficiency of imidazolium ionic liquids as collectors: Insights from dynamic surface tension and solvation analysis, Int. J. Miner. Metall. Mater., 31(2024), No. 12, pp.2645-2656. https://dx.doi.org/10.1007/s12613-024-2835-6
Qian Cheng, Zerui Lei, Guangjun Mei, and Jianhua Chen, Impact of ethanol on the flotation efficiency of imidazolium ionic liquids as collectors: Insights from dynamic surface tension and solvation analysis, Int. J. Miner. Metall. Mater., 31(2024), No. 12, pp.2645-2656. https://dx.doi.org/10.1007/s12613-024-2835-6
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以动态表面张力和溶剂化视角研究乙醇对两种咪唑离子液体捕收剂浮选效率的差异性影响

摘要: 在深入研究离子液体作为捕收剂应用于矿物浮选的过程中,采用了乙醇(EtOH)为溶剂溶解疏水离子液体(ILs),以简化药剂制度。由此观察到一些特殊现象,即EtOH对两种结构相似的ILs的浮选效率有不同的影响。纯矿物试验中, 1-十二烷基-3-甲基咪唑氯(C12mimCl)浓度为1 × 10−5 mol·L−1时,与C12mimCl(水溶剂)相比, C12mimCl(EtOH溶剂)浮选石英的回收率从23.77%提高到77.91%。但在相同条件下,1-十二烷基-3-甲基咪唑六氟磷酸盐(C12mimPF6)浮选石英的回收率从60.45%下降到24.52%。ILs浓度为 1 × 10−5 mol·L−1的 EtOH浓度条件试验,以及EtOH体积比2%的ILs浓度条件试验证实了这种差异。混合矿浮选中,C12mimCl(EtOH溶剂)的赤铁矿精矿品位和回收率相比于C12mimCl(水溶剂)显著降低,而C12mimPF6(EtOH溶剂)的赤铁矿精矿品位和回收率却大幅提高。基于浮选中观察到的泡沫差异,进行了两相气泡观测试验。在充气过程中,EtOH使两种ILs的泡沫高度均提高。停止充气后,两者静态泡沫消泡速度均加快,其中C12mimPF6泡沫消泡速度极快。讨论中采用动态表面张力效应和溶剂化效应来解释EtOH对两种ILs差异性影响背后的原因和机制。后又通过傅里叶红外(FT-IR)、x射线光电子能谱(XPS)和Zeta电位测试验证了溶剂化效果。虽然EtOH会对浮选过程中ILs在矿石表面的吸附产生负面影响,但其抑制浮选充气过程中的泡沫兼并,并加速静态泡沫消泡速度的特性具有好的发展价值。这也使得C12mimPF6混合矿浮选中出现了更强的二次富集效应,即使在无抑制剂条件下也能实现有效的混合矿石分离。

 

Impact of ethanol on the flotation efficiency of imidazolium ionic liquids as collectors: Insights from dynamic surface tension and solvation analysis

Abstract: To conduct extensive research on the application of ionic liquids as collectors in mineral flotation, ethanol (EtOH) was used as a solvent to dissolve hydrophobic ionic liquids (ILs) to simplify the reagent regime. Interesting phenomena were observed in which EtOH exerted different effects on the flotation efficiency of two ILs with similar structures. When EtOH was used to dissolve 1-dodecyl-3-methylimidazolium chloride (C12mimCl) and as a collector for pure quartz flotation tests at a concentration of 1 × 10−5 mol·L−1, quartz recovery increased from 23.77% to 77.91% compared with ILs dissolved in water. However, quartz recovery of 1-dodecyl-3-methylimidazolium hexafluorophosphate (C12mimPF6) decreased from 60.45% to 24.52% under the same conditions. The conditional experiments under 1 × 10−5 mol·L−1 ILs for EtOH concentration and under 2vol% EtOH for ILs concentration confirmed this difference. After being affected by EtOH, the mixed ore flotation tests of quartz and hematite showed a decrease in the hematite concentrate grade and recovery for the C12mimCl collector, whereas the hematite concentrate grade and recovery for the C12mimPF6 collector increased. On the basis of these differences and observations of flotation foam, two-phase bubble observation tests were carried out. The EtOH promoted the foam height of two ILs during aeration. It accelerated static froth defoaming after aeration stopped, and the foam of C12mimPF6 defoaming especially quickly. In the discussion of flotation tests and foam observation, an attempt was made to explain the reasons and mechanisms behind the diverse phenomena using the dynamic surface tension effect and solvation effect results from EtOH. The solvation effect was verified through Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), and Zeta potential tests. Although EtOH affects the adsorption of ILs on the ore surface during flotation negatively, it holds an positive value of inhibiting foam merging during flotation aeration and accelerating the defoaming of static foam. And induce more robust secondary enrichment in the mixed ore flotation of the C12mimPF6 collector, facilitating effective mixed ore separation even under inhibitor-free conditions.

 

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