Mixed surfactants with solubilization behaviors: Separation of feldspar and quartz by self-assembly flotation

[Display omitted] •The introduction of alkanes to solubilize the mixed surfactants.•Different self-assembly adsorption of quartz and feldspar was achieved.•A new non-flocculant aggregation on the surface of quartz was discovered.•The maximum flotation difference between quartz and feldspar reaches 91.36 % This study designed a mixed surfactant with solubilization behavior for selective flotation separation of feldspar and quartz. By optimizing the compounding ratio and dosage of reagents, the optimal mixed surfactants, dodecylamine (DDA), sodium dodecyl sulfate (SDS), and dodecane with the concentrations of 1.75, 0.58, and 3.5 mmol/L, used in flotation separation of feldspar and quartz has the maximum flotation difference of 91.36 % at pH 3 for single mineral. The result of flotation experiments of artificial-mixed-ore shows that the Al2O3 grade was maintained at 14.23 %, and Al2O3 recovery was achieved at 69.21 % for the froth product with a selectivity index (SI) of 1.59. The bench-scale flotation tests confirmed a better effect by using mixed surfactants with Al2O3 grades of 14.72 % and the Al2O3 recovery of 66.62 %. The separation mechanism of quartz and feldspar was proposed through analyses of critical micelle concentration (CMC), fourier transform infrared spectrometer (FTIR), contact angle, zeta potential, microscopy image, and X-ray photoelectron spectroscopy (XPS) measurements, and indicated that the flotation difference between quartz and feldspar mainly originated from the selective adsorption of anions on feldspar and the aggregation and subsidence of quartz in mixed surfactants.