Clean flotation of fine coal assisted by renewable collector prepared from waste oils

Two innovative collectors, i.e. ionic collectors and microemulsion collector were prepared from waste oil to achieve clean flotation of fine coal by gradient flotation, which helps to reduce dependence on traditional nonrenewable collectors. Ionic collectors were prepared and used for the removal of gangue particles from fine coal. Further, the biodiesel prepared from waste oil was emulsified to improve the dispersibility, and microemulsion collector was used for deep purification of fine coal. The effect of microemulsion collector dosage on flotation kinetics was also analyzed. The flotation results show that the ionic collector can effectively remove the gangue particles. When the ionic collector dosage is 1500 g/t, the ash removal reaches 43.63% with 9.17% combustible loss. Zeta analysis shows that the negative electricity on the particle surface hindered the adsorption of gangue particles and collectors in the neutral environment. The flotation kinetics test results of microemulsion collector show that the flotation rate of particles increases with the increase of collector dosage. The first-order model adopted in this study has good fitting accuracy. This study provides an environmentally friendly flotation process for fine coal and realizes the utilization of waste oil.