Flotation separation of feldspar from quartz using sodium fluosilicate as a selective depressant

Abstract The physical and chemical properties of feldspar and quartz are highly similar, thus they cannot be easily separated effectively. In this work, the flotation separation of feldspar from quartz using sodium fluosilicate (Na 2 SiF 6 ; SF) as a selective depressant was investigated. Moreover, the influence mechanism of SF on the selective flotation separation of feldspar and quartz was investigated via flotation tests, chemical analysis of flotation solution, Fourier transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS) and contact angle analysis. The results of the flotation tests show that feldspar and quartz without SF treatment have good floatability. After SF treatment, feldspar still has good floatability, whereas quartz has significantly reduced floatability. Flotation solution chemical analysis shows that the functional group plays an important role in depressing the quartz is [SiF 6 ] 2− . FTIR, XPS and contact angle analysis results show that [SiF 6 ] 2− is adsorbed only on the surface of quartz. Thus, a thin hydrophilic SiOF layer is generated on the surface, which interferes with the adsorption of the collector on the surface of the quartz. This phenomenon leads to a significant reduction in quartz’s floatability. Therefore, SF has a good ability to separate feldspar from quartz by flotation.