Interface adsorption mechanism of 5-nonyl salicylaldehyde oxime on malachite surface and its flotation separation performance with calcite and quartz

In this study, 5-nonyl salicylaldoxime (5-NSA) was synthesized and used as a malachite collector. Its flotation performances and adsorption mechanism were systematically investigated by micro-flotation experiments, contact angle measurements, SEM-EDS, FT-IR, XPS and DFTB+ simulations. The micro-flotation test results showed that 5-NSA produced high recovery of malachite at pH 9.0–10.0, while showing low collecting power to calcite or quartz. The contact angle analysis results indicated that the hydrophobicity of malachite surface was promoted after the adsorption of 5-NSA. SEM confirmed the adsorption of 5-NSA on malachite surface. FT-IR and XPS analysis results confirmed that O and N atoms in the oxime group were immobilized on malachite surface with Cu through OCuO and NCuO bonding. Their adsorption performances on malachite surface were simulated by DFTB+ method, including 5-NSA, tert-butylsalicylaldehyde oxime (TBSA) and salicylaldoxime agents, which analyzed the bond lengths of their covalent bond formation with Cu and speculated their adsorption properties. In general, according to the experimental test and simulation results, 5-NSA showed a stronger power to malachite than TBSA and salicylaldoxime, and only a small dosage can produce a high malachite recovery. The findings of this research will be helpful to improve the comprehensive utilization efficiency of malachite and promote the metallurgy of copper oxide ores.