Effect of nanoparticles on froth stability and bubble size distribution in flotation

In order to investigate the usability of nanomaterials as a froth stabiliser in mineral flotation, an experimental study was performed using a froth column and a modified flotation cell. Four different nanomaterials, namely SiO2, TiO2, Fe2O3 and Al2O3, were used in the experiments. The froth column tests were carried out to measure the Sauter-mean bubble size and dynamic froth stability under different operating conditions. Single mineral flotation tests with or without the nanomaterials were performed using a pure barite sample. Results of the froth column tests show that despite of the increasing froth height, the bubble coalescence in the froth or bursting on the surface can be decreased considerably by using the nanomaterials. The effect of the increase in froth height on the Sauter-mean bubble size and the bubble coalescence was found to be negligible by using the nanomaterials in all pH values used. These effects of the nanomaterials could not be attributed to both signs and magnitudes of their surface charges. It was determined that the nanomaterials used in this study did not contribute to the flotation efficiency at shallow froth. Contrary to this, the nanomaterials, in particular nano-sized Fe2O3 and Al2O3, provide a significant increase in barite recovery (7-11%) at deep froth, which means that selection of the type of the nanomaterials to be used in flotation is also important. As a result of the use of the nanomaterial, the decrease in the flotation performance at deep froths was found to be negligible. (C) 2015 Elsevier B.V. All rights reserved.