Interactions Between Sodium Oleate and Polyoxyethylene Ether and the Application in the Low-Temperature Flotation of Scheelite at 283 K

The poor collecting performance of fatty acids at low temperatures is a problem in mineral flotation. In this study, the floatability of scheelite at 283 K was studied using sodium oleate and binary mixtures of sodium oleate and lauryl alcohol polyoxyethylene ether (MOA-9) as the collector, and interactions between the two surfactants at 283 K were investigated by the means of surface tension and steady state fluorescence measurements. The flotation experiment results show that the collecting performance of the mixed anonic/nonionic collector is stronger than that of single surfactant, and the best molar ratio of sodium oleate to MOA-9 is 10:1 at pH 10. The surface tension results show that the critical micelle concentration value of sodium oleate, MOA-9 and the binary solution is about 2 x 10(-4), 2.5 x 10(-4), and 1.2 x 10(-4) mol/l, respectively. Compared with single surfactants, the mixture exhibits better surface activities since it is more efficient at decreasing the air-water surface tension. The steady state fluorescence results indicate that the hydrophobic parts of MOA-9 molecules insert into the hydrophobic region of sodium oleate micelles to form larger and less compact mixed micelles. The decrease in zeta potential of scheelite treated with the mixed collector indicates the presence of MOA-9 can enhance the chemical adsorption of sodium oleate on the scheelite surface. Therefore, the mixed anonic/nonionic collector can enhance the flotation behavior of scheelite at 283 K.