Metal ion transfer between sulphide minerals and effect on xanthate interaction with pyrite

Metal ion production by minerals alone and in pairs was studied by solution analysis, extraction with ethylene diamine tetraacetate (EDTA) and laser ion mass spectroscopy (LIMS) for combinations of pyrite, pyrrhotite, galena, and sphalerite. The effect of grinding, pH, and the presence of xanthate was studied. Metal ion transfer between sulphide minerals was determined.Metal ion production with minerals in pairs was different from that for single minerals. The amount of metal ion in solution followed a galvanic interaction model, increasing for the anodic mineral and decreasing for the cathodic mineral. However, from the EDTA extraction technique, the concentration of metal ions on the mineral surface increased for both minerals. The mechanism of additional metal ion production on the cathodic mineral is unclear, but may be related to reaction between the mineral and OH ions formed on the surface as a result of galvanic interaction.Metal ions transferred between two minerals in contact. In the case of pairing with pyrite, the larger proportion of Fe remained on pyrite, while 50% or more of Zn (from sphalerite) and Pb (from galena) transferred to pyrite.The effect of Pb ions on pyrite in the presence of xanthate, and diethylene triamine (DETA) was investigated by cyclic voltammetry, ex situ spectroelectrochemical analysis and zeta potential measurements.Once pyrite was contaminated by Pb ions, uptake of xanthate was promoted at pHs 9.2 and 10.5 with lime as pH modifier. The source of Pb--from solution or from contact with galena--was not a factor, and the effect was evident at Pb concentrations as low as 1 ppm. With soda ash as pH modifier, the effect of Pb was suppressed, perhaps due to formation of lead carbonate. The only xanthate product detected was dixanthogen, unless an initial potential less than $-$800 mV/SCE was imposed (when Pb$ sp{2+}$ is reduced to Pb$ sp0)$ and lead xanthate formed.Xanthate adsorption on Pb-contaminated pyrite was suppressed by DETA, but relatively large concentrations were required. DETA decreased the potential at the mineral/solution interface, which retarded oxidation of xanthate to dixanthogen.A mechanism of Pb "activation" of pyrite was proposed: adsorption of Pb(OH)$ sp+$ on pyrite provided sites for xanthate adsorption forming Pb(OH)X, on which xanthate ions were attached by hydrophobic interaction and oxidised to dixanthogen