Green, multiple-ligand collector sodium myristoyl glutamate for flotation of smithsonite

[Display omitted] •A green collector with multiple ligands (SMG) was used in smithsonite flotation.•SMG enables efficient separation of smithsonite and calcite with CLS as a depressant.•The amide groups increase the coordination ability of the COOH groups in SMG.•SMG exhibits better collecting ability than conventional collectors, and are more compatible and environmentally friendly. Zinc oxide ore containing smithsonite is a refractory ore, and it is difficult to separate smithsonite and calcite with traditional flotation collectors. A new collector was developed in this study, the multiligand biodegradable biosurfactant sodium myristoyl glutamate (SMG), which used calcium lignosulfonate (CLS) as a calcite depressant for the flotation of smithsonite. Microflotation experiments showed that SMG was an effective smithsonite flotation collector, with a recovery of more than 95 % after it reached a specific concentration. Adding CLS could achieve a considerable difference in flotation recovery rates between smithsonite and calcite. Adsorption of the collector on the mineral surface was analyzed. The contact angle, zeta potential, Fourier transform infrared (FTIR) spectra, X-ray photoelectron spectra (XPS), and atomic force microscopy (AFM) results confirmed that SMG was strongly adsorbed on smithsonite. Moreover, the depressant CLS was strongly adsorbed on the surface of calcite, and less was adsorbed on the surface of smithsonite. Density functional theory (DFT) calculations confirmed that the amino group in SMG promoted the binding of adjacent carboxyl groups to metal sites on the mineral surface. These results indicated that SMG, which is a biodegradable biosurfactant, is a promising collector for the selective recovery of smithsonite from calcite through flotation.