Quartz did not float significantly at any pH value between pH2 and pH12 when any of the anionic collectors were used. The flotation of alumina with anionic collectors is depicted in figure 1. It can be seen that SOL functions as a good collector for alumina over most of the pH range studied, the recovery of alumina falling off only at pH values below pH4 and above pH10. It is significant to note that this collector functions below, at, and above the Point of Zero Charge (PZC) of alumina. The PZC of most aluminas lie between pH7 and 9.2 and the PZC of the alumina used in this study was found to be near pH7. Of the other anionic collectors the “Zonyl” FSA and SDS functioned rather similarly, differing only at pH values below pH4. Concentration of SDS was greater than that of FSA, however. This indicates that, FSA is a somewhat stronger collector for alumina than is SDS. Collector “Zonyl” FSP, although behaving qualitatively in the manner of FSA, appeared to be a weaker collector for alumina at any particular pH value, at least as compared to this other fluorosurfactant. Again it should be kept in mind that SOL and SDS concentrations were an order of magnitude greater than the concentrations of FSP and FSA.
Both cationic collectors studied, “Zonyl” FSC and DAC, functioned as very good collectors for quartz (Figure 2) with FSC appearing to be the stronger of the two considering the slightly greater pH range of flotation, slightly greater recoveries and lesser concentration in solution.
Both cationic collectors floated alumina above the minerals’ PZC’s (Figure 3). Although DAC seemed slightly the stronger of the two for flotation of this mineral, collector concentration of this collector was ten times greater so that the result is not at all certain. Indeed the actual collecting strengths are probably nearly equal.
All amphoteric surfactants proved to be collectors for quartz and their flotation versus pH curves were roughly symmetrical (Figure 4). The collector with the widest pH region of good flotation was DPL with better than 80% recovery between pH3- and pH7+. CAP exhibited a narrower pH range of flotation in spite of the greater quantity of this surfactant present. The pH of maximum recovery using this collector was near pH5. FSB appeared to be a weaker collector for quartz than DPL exhibiting a maximum flotation recovery of about 50% near pH6. Collector concentrations for DPL and FSB were 10-5 M while collector concentration for CAP was 10-4 M.