A fundamental study of monovalent and divalent ions on froth properties in the presence of terpenic oil

In order to minimize fresh water usage, much attention has been paid to the flotation using saline or sea water. However, the effects of various ions in these waters on froth properties in flotation are not fully understood. In this study, the effects of electrolyte solutions containing NaCl, KCl, CaCl2, and MgCl2 at different concentrations in the presence of terpenic oil as a frother were investigated on froth performance, dynamic froth stability (DFS). It was found that KCl had the best synergistic effects with terpenic oil in reducing the solution surface tension. In the presence of terpenic oil, the DFS and half-life time were reduced with the increased ion concentration. Dynamics foamability index measurements (DFI) confirmed that the increased ion concentration increased the foamability, as frother did. In addition, Gibbs adsorption isotherm suggested that the amount of terpenic oil adsorbed at the gas-liquid interface was increased with the increased ion concentration. This study therefore indicated that the presence of ions can reduce the froth stability but not decline foamability due to terpenic oil, enlighting the application of saline or sea water in defoaming process in flotation.