Insights into the separation of chalcopyrite from pyrite in Mg and Ca using gum acacia, xanthomonas campestris and guar gum: An experimental study validated by theoretical investigations

Abstract

The surface chemistry of chalcopyrite (Cpy) and pyrite (Py) in presence of water containing with Mg and Ca was studied using gum acacia (GA), xanthomonas campestris (XC) and guar gum (GG) as depressants. The adsorption density of XC and GA beyond IEP of Cpy and Py in absence of metal ions was nil, whereas that of GG increased with increase in pH till at pH 9.4. However, in presence of Mg and Ca, the adsorption of XC was higher than that of GA and that of GG was higher onto mineral-metal than onto mineral. Further, the adsorption of XC, GA and GG onto mineral-Mg was more than that onto mineral-Ca and this was due to higher maximum molecular electrostatic potential (MESP) of Mg species (413.3 kcal/mol) relative to Ca species (253 kcal/mol). Additionally, the polysaccharides’ adsorption onto Py-Ca and Py-Mg was higher than onto Cpy-Mg and Cpy-Ca. On Cpy and Py with metal ions, the adsorption of XC and GA decreased with increase in pH attesting to polysaccharides anionicity. Theoretical analysis of complexes formed on Py and Cpy surfaces containing Mg and Ca, and polysaccharides was due to conventional hydrogen bonding, non-covalent and partially covalent bonding. Flotation of synthetic mixture of Py and Cpy (1:1) in presence of Mg at pH 9.5 performed better than other systems yielding Cu grade and recovery of 31.1 % and 85.6 % after 80 g/t of XC. Therefore, XC is a potential Py depressant in presence of Ca and Mg species.