Revisiting the enhanced selectivity in low-rank coal flotation by composite collector comprising kerosene and sorbitan mono oleate

Abstract

In this study, the impact of KS collectors (blends of kerosene and span80) on flotation selectivity and the underlying mechanism were investigated to comprehensively understand the non-ionic composite collectors in low-rank coal flotation. Results demonstrate that Gaudin's selectivity indices are in the range 3.19–3.61 for kerosene at dosages in the range 2–10 kg/t, but 6.58–10.81 for KS collectors at dosages in the range 2–6 kg/t. This improved flotation selectivity was because the increase of gangue recovery was overshadowed by that of combustible recovery with the KS collectors. Results also revealed that, owing to span80, coal surface hydrophobicity was enhanced, thereby improving the true flotation recovery. Meanwhile, as a result of strengthened froth stability by span80, both water recovery and the degree of entrainment increased, resulting in the increased gangue recovery. In addition, proper usage of span80 for low-rank coal flotation was also highlighted in this study.