Foaming Properties of Flotation Frothers at High Electrolyte Concentrations

摘要

The effect of ionic strength (NaCl solutions, and sea water) on the foaming properties of the flotation frothers (MIBC and DF-250) have been investigated. It was found that the foam-ability of these frothers is higher in electrolyte solutions and sea water than in distilled water. These results are in a good agreement with bubble size measurements, which demonstrate that bubble coalescence is inhibited in electrolyte solutions and in sea water. The effect of MIBC and DF-250 on surface tension of aqueous solutions varying in ionic strength is found to be very different. The presence of NaCl in aqueous solutions increases surface tension of water over a broad MIBC concentrations ranges of up to 120 ppm. In the case DF-250 this is observed only in the frother concentration range of up to 1.2 ppm; at higher DF-250 concentrations the surface tension of the aqueous solutions is reduced below the values measured in the absence of NaCl. This by itself indicates much higher surface activity of DF-250 in comparison with that of MIBC. Foamability measurements for the two tested frothers carried out at varying NaCl concentrations confirm these conclusions. Increasing NaCl concentration was found to increase dynamic foamability index (DFI), this increase is much more pronounced for DF-250 than for MIBC.