Flotation and co–adsorption of mixed collectors octanohydroxamic acid/sodium oleate on bastnaesite

Abstract

Octanohydroxamic acid (OHA) and sodium oleate (NaOL) were employed as mixed collectors to reduce the cost, increase the recovery, and retain the selectivity for the flotation of bastnaesite. Flotation experiments, zeta potential measurements, Fourier transform infrared (FTIR) spectroscopy, pyrene fluorescence measurements and X-ray photoelectron spectroscopy (XPS) were used to investigate the flotation and possible adsorption mechanism of mixed OHA/NaOL collectors on bastnaesite. The flotation experiments show that a lower dosage of mixed OHA/NaOL collectors (total concentration 1 × 10−4 mol/L, OHA:NaOL = 2:1 at pH 7) can achieve a recovery of 94.02%, which is 33% higher than that using single OHA at the same condition. Zeta potential measurements and FTIR analyses indicate that OHA/NaOL chemisorb more strongly on bastnaesite surface than each of its components. Pyrene fluorescence measurements illustrate that the critical micelle concentration (CMC) of the mixed OHA/NaOL is lower than that of either component alone, together with a higher adsorption density on bastnaesite. XPS measurements show a new peak at 288.4 eV and an increase in the C (1s) peak intensity at 284.8 eV from 15.87% to 37.85% when using the mixed OHA/NaOL. Therefore, the mixed collectors have a stronger flotation ability and produce a thicker adsorption layer.