The mechanism of adsorption of anion surfactant (naphthalene sulfonic acid sodium formalin condensate) on various coals in CWM were studied and the following results were ob-tained.
Grain size of coals did not have effect on amount of equilibrium adsorption of surfactant. As for the adsorption rate of surfactant on coals, it was dominated by diffusion rate for pores of coals. The ad-sorption equilibrium of surfactant showed a type of Freundlich in low concentration region. The dif-ference of saturated amount of surfactant which is adsorbed on various coals is due to various accep-tabilities of adsorption site allocation.