The influence of polymeric dispersants on sericite–chalcocite particle interactions in aqueous media

Unexpected sericite–chalcocite mineral particles’ hetero-aggregation occurs under aqueous processing conditions where both minerals display negative zeta potentials. In this study, the use of anionic co-polymers (carboxylate- versus sulphonate-substituted) as dispersants to suppress the hetero-aggregation behaviour was investigated in the pH range 5–9. Both polymers showed strong substrate and pH-dependent adsorption and electrokinetic potential characteristics onto both minerals. The adsorption propensity was considerably higher onto chalcocite than sericite particles and dramatically accentuated at pH 5 for the former due to leached electropositive Cu(II) species’ surface activation effect. At high polymer dosages (>1.5 g kg−1 solid) leading to plateau adsorption density, the magnitude of both mineral particles’ zeta potential increased to a maximum. Furthermore, the adsorbed polymer layer dominated the interfacial chemistry that showed subtle mineral phase and pH dependency. The concomitant particle interactions reflected a marked reduction of dispersion shear yield stress and the suppression of sericite–chalcocite particulate adsorption. Electro-steric repulsive forces are believed to be responsible for the dispersing mechanism. Both polymers displayed similar, high dispersing efficacy at dosages >1.5 g kg−1 solid for sericite–chalcocite mix dispersions, regardless of the pH.