Effect of Water Quality on Froth Stability in Flotation

In flotation, the froth structure and froth stability are known to play a significant role in determining the mineral concentrate grade and recovery. Froth stability is not only depending on the type and amount of the frother used, but also on the amount and nature of the suspended particles. Furthermore, there are other parameters such as quality of water which are not yet fully understood. In plant practice, the recycling of process water (and very often of water from different sources) to reduce freshwater consumption is increasingly being common. However, using recycled water normally leads to the build-up of salts and surfactants in solution. Therefore, the effect of the process water chemistry on froth stability and more in general on the metallurgical performance, is important. In this study, the effect of water quality, including pH and type and concentration of salts (such as CaCl2, AlCl3 and NaCl) on froth stability and viscosity was studied. It was found that forth stability was higher in the presence of multivalent metal ions, at concentrations ranging between 15 and 40 mg/L. CaCl2 and AlCl3 considerably increased the froth stability (and viscosity). This may be due to bridging effect of polyvalent metal ions between the ore particles.