Stability and flotation behaviour of silica in the presence of a non-polar oil and cationic surfactant

This present work deals with the stability and flotation efficiency of silica in the presence of a cationic surfactant, dodecylamine (DDA) and a non-polar oil, dodecane. Dispersion stability was defined by turbidity measures and the flotation tests were carried out in a laboratory scale flotation cell. Results from stability measurements indicated that DDA caused extensive aggregation at concentrations of 600–12,000 g/t (DDA/silica) (0.17–3.34 mM). Increasing the dodecane concentration from 0–2730 g/t (0–0.81 mM) in a DDA-silica system was found to have no effect on the stability of the silica particles. Flotation data showed that the addition of dodecane with DDA in combination increased the removal rate of silica particles. The effect of dodecane addition rate on the bubble size and bubble clustering in the flotation cell was also investigated. A specifically designed cell was used to view bubbles in the cell and their images were recorded using a high speed camera. By using an image analyzer the cluster size, the average size of bubbles in the clusters and independent bubbles, i.e. those had not aggregated were investigated as a function of dodecane concentration. The average bubble size was found to be affected by dodecane dosage.