Effect of magnetic seeding agglomeration on flotation of fine minerals

Magnetic seeding agglomeration (MSA), i.e., adding magnetic seeds and a low intensity pre-magnetization for fine agglomeration, was applied to the flotation of coal, pyrite and hematite ore slimes. Size analysis and flotation tests highlight that the MSA improved flotation recovery and kinetics of pyrite ore while causing some loss in selectivity, and in the presences of the polyacrylamide for coal and starch for hematite the agglomeration flotation was further strengthened due to the synergetic effect between the flocculants and magnetic seeds. Magnetism analyses and calculation confirmed the adsorption of magnetic seeds onto minerals, resulting in a decreased threshold magnetic field intensity for the MSA to happen. Then atomic force microscope (AFM) study found that there exists a long range force between magnetic seeds and minerals, which facilitates the adsorption of magnetic seeds on minerals. FTIR shows both the polyacrylamide and starch adsorbed onto minerals and magnetic seeds, thus acting as the bridging media between minerals and magnetic seeds, intensifying the agglomeration in flotation. Surface characterization of the MSA was understood by SEM imaging, and models of the MSA were proposed.