Influence of surface roughness of magnesite on bubble-particle energy barrier: Analysis based on a new simplified model

The surface roughness of mineral particles treated by different methods varies greatly, which will significantly affect flotation operations. In this investigation, magnesite particles with different surface roughness were obtained by ultrasonic treatment for different times. A new simplified mathematical model of rough particle-bubble interaction energy based on the extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) theory was formulated. Theoretical analysis shows that it is essentially consistent with the Wenzel wetting model. The parameters in the model were obtained by contact angle test, zeta potential test and AFM test. The interaction energy between a rough magnesite particle and a bubble at different NaOL concentrations was calculated. The results indicate that increasing the surface roughness of hydrophobic magnesite particles can significantly reduce the value of energy barrier (Em) that needed to be overcome for the adsorption between bubbles and magnesite particles. Meanwhile, it can push the location of energy barrier further away (that is, increase the critical hydration film thickness hcr when bubble-particle adhesion occurs), allowing magnesite particles to adhere to bubbles earlier and more easily, thereby improving the flotation performance of magnesite particles. However, the promoting effect of increasing surface roughness on the flotation of magnesite particles gradually weakened as the concentration of NaOL increased.