Experimental and theoretical investigation on the separation of chalcopyrite from biotite using xanthan gum as a selective depressant

The separation of chalcopyrite from biotite using xanthan gum (XG) as a selective depressant was carried out experimentally and various types of intermolecular interactions present in the resultant complexes were analyzed theoretically. It was observed that the adsorption density of XG for chalcopyrite and biotite decreases with increase in pH. The Gibbs free energy of adsorption of XG at pH 8.5 +/- 0.1 onto biotite (-32.5 kJ/mol) was more than that onto chalcopyrite (-23.3 kJ/mol), attesting to chemisorption process on both systems. The higher adsorption of XG onto biotite than onto chalcopyrite was further confirmed by theoretical analysis. Additionally, the intermolecular interactions of the formed complexes on the studied minerals were probed using Quantum theory of atoms in molecules (QTAIM) and Non-covalent interaction (NCI) tools. Both QAIM and NCI tools indicated that the adsorption of XG onto chalcopyrite and biotite is governed by weak, partial covalent hydrogen bonding and other non-covalent interactions. Flotation of biotite-chalcopyrite (1:1) system in the presence of 1200 g/t of XG as a selective depressant yielded a copper grade and recovery of 32.3% and 94.8% with a selectivity index (SI) of 35.8.

Automated summary

Experimental and theoretical analysis showed that using xanthan gum as a selective depressant can effectively separate chalcopyrite from biotite. The adsorption of xanthan gum on chalcopyrite and biotite is pH-dependent, with a chemisorption process observed on both minerals. Analysis using QTAIM and NCI tools indicated that the adsorption of xanthan gum is governed by weak, partial covalent hydrogen bonding and other non-covalent interactions on both chalcopyrite and biotite.