The wetting film evolution process is essential for flotation, especially in bubble–particle attachment. A mixed collector has been proved effective in promoting flotation. In this paper, the effect of a mixed collector (MC) composed by n-dodecane (D) and oleic acid (OA) on wetting film evolution was investigated using the extended Derjagin–Landau–Verwey–Overbeek (EDLVO) theory, the Stefan–Reynolds model, induction time, and zeta potential measurement. The hydrophobic force constant between bubble and coal treated by different collectors was analyzed. The results showed that MC was superior in reducing the induction time and increasing the zeta potential. When bubbles interacted with coal treated by MC, they had relatively low interaction energy, high critical film thickness, and high drainage rate. The order of hydrophobic force constant was no reagent < D < OA < MC. It indicated that the hydrophobic interaction between bubbles and coal particles treated by MC was the strongest because of the synergistic effect of D and OA
