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Differences in Etheramines Froth Properties and the Effects on Iron Ore Flotation. Part I: Two-Phase Systems

ABSTRACT Etheramines are quartz collectors and also play a role as frothers in cationic reverse flotation of iron ores. While the adsorption of this surfactant on quartz surface has been widely investigated, the impact of its foam/froth properties on the selectivity in iron ore flotation has not yet been addressed in detail. The structural differences between ethermonoamine and etherdiamine result in distinct adsorption and frothing properties, offering versatility in the concentration of hematite. This study addressed the effect of the etheramine type on flotation selectivity, focused on the analysis of frothing properties. The characterization of the surfactants in the pure state and in two-phase systems (liquid/air) was conducted to investigate the behavior of etheramines concerning foam forming and stabilization. The surface tension measurements showed greater activity of etherdiamine at the liquid–air interface in comparison with ethermonoamine, which was more effective to prevent bubble coalescence and produce smaller bubbles, despite the reagent’s higher critical coalescence concentration. Ethermonoamine presented faster foamability for concentrations greater than the observed critical coalescence concentration values as well as greater water recovery in foam, whereas the double CH2 group and higher molecular weight imparted strong lipophilic character to etherdiamines, producing drier, voluminous, and more stable foams, with longer lifetime. These results are fundamental for the evaluation of three-phase systems, which will be presented in a subsequent paper.