Flotation intensification of low-rank coal using a new compound collector

Traditional non-polar oil collectors cannot achieve high recovery of low-rank coal because of the presence of oxygen-containing groups at coal surface. In this study, a new mixture of fossil oil and oxygen containing compound (FO) was used to enhance low-rank coal flotation compared with that using traditional collector, diesel oil. The oil droplet-particle detachment, induction-time, stability of the bubble-particle aggregate, attachment angle test and chemical force microscopy (CFM) were selected to further analyze the strengthening mechanism of collectors. The results show that higher yield was obtained using FO than that using diesel. Compared with diesel, FO was easier to adhere and spread on coal surface. The shorter induction time, higher amplitude and bigger attachment angle in presence of FO indicated that the FO treatment enabled the particles to much easily adhere to bubble. CFM provided a new insight into intensification mechanism of collector by the direct measurement of interaction force. [Display omitted] •Effectiveness of FO in low-rank coal flotation was compared with diesel.•Strength of oil droplet-particle aggregate can verify the effectiveness of collectors.•Induction time explained the strengthening mechanism from adhesion perspective.•Critical amplitude reflected the strengthening mechanism from detachment perspective.•Bubble-particle attachment angle refected the floatability of the coal by single bubble.•CFM provided a new insight into intensification mechanism of collector in coal flotation.