Investigation on the influence of surface roughness on magnetite flotation from the view of both particle-particle and bubble-particle interactions

It is well known that surface roughness of mineral particles has a significant influence on their flotation behaviors. In this investigation, magnetite was ground in rod and ball mills to generate particles with similar dimension and shape but varying degree of surface roughness, which was quantified using Atomic Force Microscopy (AFM). The influence of surface roughness on the floatability of magnetite particles was performed by flotation tests using an XFG flotation machine. Flotation tests indicated magnetite particles possessed higher surface roughness had higher flotation recovery and larger flotation rate constant. The aggregation behaviors of different rough magnetite particles were compared for the first time via an optical microscopy. Results of the optical microscopic tests revealed that there were a large number of aggregations in the system of particles with higher surface roughness. A proposed model was deduced with the parameters carefully calculated (not arbitrarily selected) to analyze the bubble-particle interaction energy using an Extended DVLO (Derjaguin–Landau–Verwey–Overbeek) theory. The theoretical interaction energy points to lowering energy barrier when magnetite particles are covered with 28.03 nm asperities as compared to 9.47 nm asperities. The effect of surface roughness on mineral flotation was investigated from the view of both particle aggregations and energy barrier of bubble-particle attachment for the first time, which are the primary causes for differences in flotation performance.