Mechanism of modified-oily-bubble flotation of Shengli lignite

Characterized by high hydrophilicity,Shengli lignite is difficult to obtain satisfactory flotation results. In or- der to inhibit hydrophilic effect of oxygen-containing groups,oily-bubble modified respectively by 2-ethyl hexanol,oc- tanone and methyl phenyl acetate was tested in flotation. Induction time was used to evaluate the adhesion capacity of modified-oily-bubble and the adsorption sites of surfactants was analyzed by FT-IR technique. Combining test results and group electronegativity,a comprehensive analysis of adsorption mechanism was carried out,which enriched the basic theory of oily-bubble flotation. The results showed that the induction time of oily-bubble modified by 2-ethyl hex- anol and octanone can be reduced to about 40 ms,meanwhile,combustible matter recovery was increased over 60% . FT-IR analysis indicates that surfactants used above could enhance the floatability of Shengli lignite mainly by inhibit hydrophilic effect of —OH. Compared the group electronegativity and test results,it can be concluded that alcoholic hydroxyl group interact with the oxygen-containing groups of lignite surface by hydrogen bond,which is the most effec- tive way. Ketonic oxygen of octanone associated with coal surface groups by covalent bond and it works well in high surfactant concentration. The benzene ring of methyl phenyl acetate was more readily to adsorb onto hydrophobic sites of coal surface,thus prevent valid interaction of agent oxygen-containing groups.