Portal de Periódicos da CAPES

Solution chemistry studies and flotation behaviour of apatite, calcite and fluorite minerals with sodium oleate collector

1985; Elsevier BV; Volume: 15; Issue: 3 Linguagem: Inglês

10.1016/0301-7516(85)90035-3

1879-3525

R.J. Pugh, Per Stenius,

Iron oxide chemistry and applications

The maximum flotation response for three naturally occurring calcium minerals, apatite, calcite and fluorite with sodium oleate collector correlated directly with the minimum interfacial tension of the air/solution interface. For fluorite and apatite the minimum surface tension occurred about the mid-pH region and was attributed to the formation of pre-micellar associated species in solution. In the case of calcite the minimum was observed at high pH since the presence of high concentrations of calcium ions in solution appeared to reduce the concentration of amphililic species in the low and mid-pH regions. Microelectrophoresis data demonstrated that the three minerals acquired a negative charge in sodium oleate solution, resulting from adsorption of oleate species on the mineral surfaces. The flotation behaviour of the systems were shown to be related to the species distribution diagrams suggesting that the role of the acid soap dimer, soap dimer, molecular and lattice species could make a significant contribution to the character and composition of the interfacial films. High flotation response was explained by strong adhesion between the hydrophobic particle and bubble. It was suggested that the reduction in surface tension may not be the major factor contributing to the flotation efficiency but indicated the presence of associated surfactant species in solution which could also synergistically adsorb at the solid/liquid interface, increasing the hydrophobic character of the mineral surface. This would maximize the magnitude of the contact angle and hence the strength of the adhesion between particle and bubble. This adsorption behaviour is not in general agreement with conventionally non-hydrolyzable collector theory which is usually based on electrostatic models.