The hydrophobic mechanism of di(2-ethylhexyl) phosphoric acid to hemimorphite flotation

In this paper, the flotation separation of hemimorphite from quartz was investigated by using di(2-ethylhexyl) phosphoric acid (DEHPA) as a collector. The results elucidated that DEHPA exhibited better flotation performances to hemimorphite than dibutyl phosphoric acid (DBP), tributyl phosphate (TBP), octanoic acid (OA) and palmitic acid (PA). And DEHPA also possessed good selectivity against quartz flotation and could realize the effective flotation separation of hemimorphite from quartz under pH 6.0-10.0. The adsorption and contact angle findings clearly indicated that DEHPA selectively adsorbed on hemimorphite, hardly on quartz. After DEHPA treatment, the hydrophobicity of hemimorphite was dramatically improved. Zeta potential suggested that DEHPA anion anchored on hemimorphite surfaces mainly through chemical bonds. FTIR inferred that DEHPA chemisorbed on to hemimorphite surfaces by formation of the Zn-O bonds between the O atoms of the P(=O) (OH) group and the surface zinc atoms, simultaneously with splitting the O-H bonds of the P-O-H group. XPS gave clear evidences that the adsorbed DEHPA combined with Zn(II) species on hemimorphite surfaces to generate the Zn(II)-DEHPA surface complexes.