Observing slime-coating of fine minerals on the lump coal surface using particle vision and measurement

Slime-coating is an important mechanism to deteriorate the concentrate grade in mineral flotation. In this paper, the slime-coating behaviors of fine kaolinite, quartz and calcite particles on the lump coal surface with various roughness were directly observed by Particle Vision and Measurement (PVM) technology, and the interaction forces between the mineral particles and the lump coal surface were calculated using the classical Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. It was found that the lump coal surface was significantly coated by kaolinite and calcite particles compared with quartz particles. The number of particles coating on the surface of the lump coal increased with the roughness of the surface of the lump coal. The particle size of the mineral particles coating on the surface of the lump coal was extremely fine. The total potential energy (E) between the calcite particles and the lump coal surface was negative, while that between the quartz particles and the lump coal surface was positive. These calculation results were consistent with the observed ones using the PVM. However, the slime-coating behavior of kaolinite particles on the surface of the lump coal cannot be explained by the DLVO theory, which might be owing to their anisotropic surface characteristics