Abstract:The surface hydrophobization and flotation of a xanthate-hydroxamate collector toward copper oxide mineral were compared with the combined collectors of xanthate and hydroxamate through water contact angle (WCA) and micro-flotation experiments. The results showed that S-[(2-hydroxyamino)-2-oxoethyl]-O-octyl-dithiocarbonate ester (HAOODE) exhibited stronger hydrophobization and better flotation performance to malachite (Cu₂(OH)₂CO₃) than octyl-hydroxamic acid (OHA) and its combination with S-allyl-O-ethyl xanthate ester (AEXE). To understand the hydrophobic intensification mechanism of HAOODE to malachite, zeta potential, atomic force microscopy (AFM) and XPS measurements were carried out. The results recommended that malachite chemisorbed HAOODE to form Cu—HAOODE complexes in which the hydroxamate—(O,O)—Cu and —O—C(—S—Cu)—S— configurations co-existed. The co-adsorption of HAOODE’s hetero-difunctional groups was more stable than the single-functional- group adsorption of OHA and AEXE, which produced the “loop” structure and intensified the self-assembly alignment of HAOODE on malachite surfaces. In addition, the “h” shape steric orientation of the double hydrophobic groups in HAOODE facilitated stronger hydrophobization toward malachite than the “line” or “V” hydrophobic carbon chains of OHA or AEXE. Thus, HAOODE achieved the preferable flotation recovery of malachite particles in comparison with OHA and AEXE.

Key words: S-[(2-hydroxyamino)-2-oxoethyl]-O-octyl-dithiocarbonate ester; atomic force microscopy (AFM); hetero- difunctional co-adsorption; hydrophobization; malachite flotation