Synthesis, Structural Characterization, and Application of a Cationic Thermo-Responsive Copolymer Based on [2-(Methacryloyloxy)ethyl]trimethylammonium Chloride and N-Vinylcaprolactam for Use with Butyl Xanthate in the Flotation of Ultrafine Chalcopyr

The flotation of finely divided chalcopyrite and quartz was investigated using a combined reagent system based on butyl xanthate and a thermosensitive cationic copolymer. Copolymers of [2-(methacryloyloxy)ethyl]trimethylammonium chloride and N-vinylcaprolactam (co(METAC/NVCL)), prepared by RAFT polymerisation, were used as the polymer components. Their structure and physicochemical properties were investigated using IR and NMR spectroscopy, gel permeation chromatography and thermal analysis. Flotation tests were carried out on an artificial mixture of chalcopyrite and quartz in a mass ratio of 1:1 at pH 8.5 and temperatures of 20–50 °C. At 40 °C, the combined use of a 70:30 copolymer and butyl xanthate, with each component at a concentration of 5 mg/L, resulted in a copper recovery of 77.68% when the copper content in the concentrate was 30.90%, and a SiO2 recovery of 5.78%. Compared with the xanthogenate process, copper recovery increased by 5.62%, whilst SiO2 recovery decreased by 1.10%.