AFM Study On Adsorption Morphology Of Quaternary Ammonium Salts Collectors And Interaction Forces Between Mineral Particles

In this paper, the flotation tests of pure mica have been performed using quaternary ammonium salt cationic collectors to study the effects of mineral particle size and carbon chain length of collector, which were based on the crystal structure of mica. The interaction forces between particles and adsorption morphology of cationic surfactants on mica were directly measured with an atomic force microscope (AFM). And combining the infrared spectrum analysis and contact angle measurement, the adsorption law and adsorption layer structure at mica-quaternary ammonium salts interface were analyzed. Furthermore, the interaction mechanisms between quaternary ammonium salt collector and mica were carried on, which provided theoretical support on the technology of layer silicate mineral flotation.The adsorption morphology of cationic surfactants from aqueous solution onto muscovite mica substrates was examined. The results show that, with the concentration increasing, the adsorbed layer on muscovite was monolayer firstly, and then became bilayer. The surfactant molecule adsorbed on the muscovite surface through an angle. The angles between alkyl chain and mica plane are decreasing with the hydrocarbon chain length increasing. The angle of1031is almost90°, while the angle of1631is almost0°. With the concentration increasing, the adsorbed structures are block�'connected block�'mesh�'laminate&sphere�'stripe structure irregularly.Interaction forces measurements between particles reveal that hydrocarbon chain length has a great impact on the interaction force. For1031, there is no hydrophobic attractive force produced in all range of concentrations, which the electrostatic repulsive-force is dominant. However, for1231,1431and1631, hydrophobic attractive forces are produced in some relatively high concentrations. There exists a concentration which has the largest attractive force between silica probe and mica surface in cationic surfactant solution. Under that concentration, the repulsive force decreases still attractive force with the concentration increasing, while the attractive force decreases over that concentration. The electrolyte and solution pHs have effects on the interaction forces.The flotation behavior of various particle size mica which use four kinds of quaternary ammonium salt cationic collectors (1031、1231、1431、1631) have been investigated. The results show that, in the conditions of coarse fraction mica which are-0.2+0.15mm and-0.15+0.075mm, the flotation recovery is relatively independent with the solution pH. The order of flotation effect of the four reagents is1031<1231<1431<1631which is correspond to the universal law. However, in the conditions of fine fraction mica which is-0.045+0.038mm, the order of flotation effect of the four reagents is1631<1431<1231which is opposite to the universal law. The crystal structure of mica and the adsorption behavior of the quaternary ammonium salt cationic collector can be used to explain this difference.