Abstract:The depression mechanism of zinc sulfate (ZnSO₄) and sodium dimethyl dithiocarbamate (DMDC) as the combined depressant on sphalerite was investigated by micro-？otation experiments, ion complexing tests, contact angle tests and X-ray photoelectron spectroscopy (XPS) analysis. The micro-？otation tests revealed that ZnSO₄+DMDC had a better selective depression effect on sphalerite than using single ZnSO₄ or DMDC. Ion complexing tests confirmed that DMDC had a strong complexing capacity with lead ions or hydroxy complexes. Contact angle tests illustrated that ZnSO₄+DMDC makes the sphalerite surface more hydrophilic than ZnSO₄ or DMDC. XPS analysis indicated that the combined depressant could prevent collector adsorbing on the Pb-activated sphalerite surface by a competitive adsorption method, while the combined depressant and collector were co-adsorbed on galena surface.

Key words: adsorption behavior; contact angle; complexation; galena; sphalerite; combined depressant