Flotation of quartz using imidazole ionic liquid collectors with different counterions

Abstract

Four kinds of ionic liquids (ILs) with different counterions were used as collectors to perform flotation tests for pure quartz and quartz-hematite mixed ore. Pure quartz flotation showed that all ILs had excellent collection performance, exceeding 95% of the quartz was floated below the concentration of 8*10−5mol*L−1. All ILs showed much better collecting capacity than DDA. Mixed ore tests without inhibitor showed the best effect using imidazole ILs with chlorine ligands as collector, 61.9% grade iron ore was obtained from the 51% TFe quartz-hematite mixed ore, and the recovery rate was 94.54%. The flotation using starch inhibitor showed that imidazole-based ILs containing hexafluorophosphate ligands achieve the highest beneficiation efficiency. It obtains 64.86% iron concentrate and 86.07% recovery rate. In the tests with inhibitor, all four ILs performed better flotation effects than DDA. X-ray photoelectron spectroscopy (XPS) investigation was conducted of quartz that was treated by ILs and DDA, and adsorption analysis was performed based on N(1S) position, N/Si ratio and C(1S) peaks. Fourier transform infrared spectroscopy (FTIR) study was also conducted, and the adsorption of ILs and DDA was further analyzed by the appearance of new peaks and the shift of peaks in IR spectrum, Zeta potential study intuitively showed the adsorption difference between the four imidazole ILs and DDA. The flotation results were discussed together with XPS, IR and Zeta potential study. In conclusion the higher charge density on the overall semi-micelle of ILs caused greater collecting capacity than that of DDA, and weaker charge of single adsorption site caused greater selectively. And, it is believed that the counterions of ILs affect the floatation effect by affecting the formation process of the semi-micelle.