Green effective separation of chalcopyrite and galena with a polymer surfactant: Synthesis performances and adsorption mechanism
Xinyao Jiang, Shiliang Sun, Anruo Luo, Yao Meng, Xingrong Zhang, Jianhua Chen
Abstract
Dichromate (K 2 Cr 2 O 7 ) has been applied in the flotation separation of chalcopyrite and galena for decades. Owing to its high toxicity, lots of efforts have been done to explore suitable alternatives. In this paper, we have synthesized a green polymer depressant, poly(acrylamide-N-thiourea maleic acid) (PATMA), via a copolymerization in water through a green production process without any three-wastes. PATMA was firstly used as a galena depressant instead of K 2 Cr 2 O 7 . Its depressing performances were evaluated by micro-flotation tests and bench-scale experiments, indicating that PATMA exhibits a stronger depressing capability and superior galena selectivity over chalcopyrite compared to the traditional depressant K 2 Cr 2 O 7 . At pH 8.5 and PATMA dosage of 2.0 mg/L, Cu-Pb separation can be achieved effectively, and the Cu recovery in Cu concentrate is 93.06 % and the Cu grade is 32.58 %. These findings suggest that PATMA could serve as a promising environment-friendly alternative to K 2 Cr 2 O 7 in the flotation separation of copper and lead. In addition, the adsorption mechanism of PATMA at galena interface was examined through contact angle test, FT-IR, XPS, SEM-EDS and DFTB + simulations. The results indicate that PATMA undergoes a chemical reaction with lead species through the C = S group present in its own structure, resulting in the formation of a C-S-Pb structure that is chemically adsorbed onto the surface of galena. At the same time, the adsorption behavior of PATMA on the galena surface was simulated by using the DFTB + calculation method. The results further confirmed that the C-S-Pb bond between PATMA and galena was chemically adsorbed onto the galena surface.