Depression mechanism of peracetic acid for flotation separation of chalcopyrite from arsenopyrite based on coordination chemistry

A highly selective depressant is of critical importance for efficient Cu-As separation. Herein, the depression mechanism of peracetic acid (PAA) with respect to arsenopyrite is systematically analysed at the microscopic level using density functional theory calculations, molecular dynamics simulations, X-ray photoelectron spectroscopy and coordination chemistry. The adsorption energy of PAA on FeAsS (0 0 1) surfaces is − 550.5 kJ/mol. Both, the single-bonded O (O1) and double-bonded O (O2) atoms of PAA are simultaneously adsorbed onto the Fe atoms of the FeAsS (0 0 1) surfaces, but the covalent bond formed by the O1 and Fe atoms is more stable. Oxidised arsenopyrite surfaces contain an abundance of Fe(III)-O species, while the state of the Cu and Fe atoms on the chalcopyrite surface does not change significantly. The σ-coordination effect of the PAA molecules is more likely to provide lone-pair electrons to the empty eg orbital of the Fe2+ ions on the surface of arsenopyrite than to those on chalcopyrite surfaces. The three pairs of π-electrons in the t2g orbital of the Fe2+ ions on arsenopyrite surfaces are more likely to interact with the empty π-orbital of the PAA molecule in a π-backbonding interaction.