Uncovering the flotation performance and adsorption mechanism of a multifunctional thiocarbamate collector on malachite

In this paper, a novel collector N-octanoyl-S-carboxyethyl thiocarbamate (OCETC) containing CO, CS and -COOH groups was synthesized and applied to recover malachite. The flotation performance and adsorption mechanism of OCETC on malachite surface were systematically investigated by DFT calculation, zeta potential, FTIR, XPS, contact angle measurements and flotation experiments. It was found that CO, CS and -COOH groups were the functional sites which could react with Cu(II) ions on malachite surface and formed COCu(I) and CSCu(I) bonds. The adsorption of OCETC on malachite surface significantly improved its surface hydrophobicity since the contact angle of water on malachite changed from 46.5° to 78.0°. The flotation experiments demonstrated that 6 × 10−5 mol/L OCETC enabled the recovery of up to 98.24% malachite at pH 8.0. Under the same flotation conditions, OCETC exhibited comparable flotation recovery for malachite compared to octyl hydroxamic acid (98.43%), but much better than that by benzoyl hydroxamic acid (54.13%).