Cleaning high ash coal waste from coking coal via froth flotation method

Abstract

In this work, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and laser particle size methods were employed. The surface of the particle obtained from the cyclonic-static microbubble flotation column (FCSMC) concentrate was coated with numerous small particles when compared to the clean coal collected from the Denver flotation cell. Even though the mass recovery of FCMSC concentrate (51.13%) was approximately twice the mass yield of Denver flotation cell concentrate (26.66%), the ash content in FCSMC concentrate (33.07%) was higher than that of the Denver flotation cell concentrate (14.88%). This result can be attributed to the advantages of FCSMC in small coal particle flotation, and this resulted in the misplacement of coarser particles with lower ash content in the tailing. The highest mass recovery of 0.250–0.500 mm in magnesium ion solution was 95.39%, which was slightly high than that (92.84%) in calcium ion solution. However, the concentrate ash content with 0.250–0.500 mm coarse size fraction in magnesium ion solution was 11.41%, which was higher than that (11.14%) in calcium ion solution. Flotation performances of different size fractions in rougher-cleaner flowsheet indicated that flotation responses in calcium ion solution were better than that in magnesium solution.