Research On The Influence Of Surface Roughness On The Interaction Of Chalcopyrite/Calcite With Air Bubbles/Droplets

China’s copper ore resources are characterised as fine,poor and miscellaneous.Flotation is an effective way to separate and enrich copper-bearing minerals.The choice of crushing and grinding processes and equipment prior to flotation influences to some extent the microscopic surface morphology and roughness characteristics of the mineral particles,which also have an important influence on their flotation behaviour.In order to elucidate the mechanism of the influence of the surface roughness of mineral particles on their flotation behaviour during flotation separation,a typical copper-bearing mineral,chalcopyrite,and its vein mineral,calcite,were selected as the objects of this research.The wetting characteristics of water on chalcopyrite and calcite surfaces with different roughness were examined and a relationship between surface roughness and surface wettability was established.The adhesion behaviour of bubbles on mineral surfaces of different roughness was analysed,and the effects of p H and flotation agent concentration on the adhesion of bubbles on mineral surfaces with different roughness were investigated.A theoretical link between agent concentration,surface roughness and the formation and spreading characteristics of the bubble-mineral three-phase contact line was established.This research will enrich the theory related to the influence of mineral particle surface micromorphology on flotation behaviour and have some theoretical implications for the rational selection of grinding processes and equipment.The main findings of the study are:With the increase of surface roughness,the contact angle of chalcopyrite surface increased and the contact angle of calcite surface decreased,and the two change in an opposite trend.Wetting hysteresis on chalcopyrite and calcite surfaces with different surface roughness was found to be more pronounced on the rougher chalcopyrite surface than on the smoother chalcopyrite,and more pronounced on the smoother calcite surface than on the rougher calcite.The Cassie wetting model is more consistent with the wettability of chalcopyrite surfaces,where the presence of air in the rough structure of the mineral surface is the main obstacle to droplet spreading,whereas the wettability of calcite surfaces is better described by the Wenzel wetting model.The increase of surface roughness favoured the adhesion of bubbles to the chalcopyrite surface and discouraged the adhesion of bubbles to the calcite surface.As the surface roughness increased,the formation of three-phase contact lines on chalcopyrite surfaces decreased,while the formation of three-phase contact lines on calcite surfaces increased,and no three-phase contact lines are formed on the rougher calcite surfaces.The three-phase contact line spreading rate of chalcopyrite and calcite increases gradually with increasing surface roughness,and the trend of the induction time is the same as the trend of the three-phase contact line formation time.The main driving force of bubble adhesion on chalcopyrite surfaces is hydrophobic gravity,while the main influence on bubble adhesion on calcite surfaces is van der Waals repulsion.Different p H values and flotation agent concentrations have a significant effect on bubble adhesion behaviour on mineral surfaces.With the increase of p H,the formation time of three-phase contact line on the surface of chalcopyrite decreases and then increases,and the spreading rate of three-phase contact line increases and then decreases.The increase of the concentration of the butyl xanthate is not conducive to the rupture of the hydration film between the bubbles and the chalcopyrite.However,once the hydration film was broken down and the three-phase contact line was been formed,it favoured the spread of the three-phase contact line across the chalcopyrite surface.In acidic environment,tiny bubbles precipitate on the calcite surface,promoting the formation of three-phase contact lines.As the p H increases,the time for the formation of three-phase contact lines on the calcite surface first decreases and then increases.The low concentration of Sodium silicate solution can better inhibit the adhesion of air bubbles on the calcite surface.