New insights into the intensification of collector adsorption on fine particles induced by flow field

Abstract

Solid surface hydrophobicity plays a crucial role in flotation recovering valuable components from fine particles, which is generally rendered by reagent adsorption. In this work, to compare the liquid − solid mixing and particle surface modification performance of two different energy input forms induced by structure design, namely the mechanical agitation and hydrodynamic flow, which corresponded to a stirred tank (ST) and a novel conditioning device with opposite rotational flow (CDORF) without any agitation impellers, flow field simulations and conditioning − flotation tests were conducted, together with the particle characterization. Results showed that compared with the radial flow dominated ST, integrated forms of convection and shear mixing effectively promoted pulp homogenization in the CDORF. Basically, electrostatic attraction could be easily completed between the changed functional groups of Si − O− and RNH3+, but hydrogen − bond affinity occurred between the species of RNH3+ and Si − OH or water molecules, thereby causing competitive adsorption to some extent, which required continuously transporting particles and reagent molecules through the area with high strain rate to clean particle surfaces and launch their interactions. Based on the simulation of particle distribution and strain rate, the CDORF exhibited compatible zones of large shear and dispersed particles. Therefore, it was found to obtain better response of the induction time and the flotation recovery of fine quartz particles per added power to the collector adsorption features. The research findings reveal that the collector − particle interaction between their functional groups could be flow field dependent, which is expected to provide references for designing and optimizing equipment related to flow process fields, especially in the solution containing surfactants.