Utilizing phosphonyl carboxylic acid copolymer as an efficient depressant for flotation separation of galena from chalcopyrite: Experimental and DFT study

The research proposes an innovative galena depressant, known as Phosphonyl carboxylic acid copolymer (POCA), to enhance the efficiency of flotation separation between chalcopyrite and galena. Mineral flotation tests were conducted to investigate the flotation performance of chalcopyrite and galena. The inhibition mechanism of POCA on galena was studied using multiple characterization techniques including Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) testing, Zeta potential testing, X-ray photoelectron spectroscopy (XPS) analysis, atomic force microscopy (AFM) testing, contact angle testing, time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis, and density functional theory (DFT) calculations. In the flotation test, at a concentration of 10 mg/L sodium butyl xanthate (SBX) and pH 9, adding 50 mg/L POCA can reduce the flotation recovery of galena from 83.50 % to below 5 %, whereas the recovery of chalcopyrite was almost influenced. The testing conducted via ICP-OES revealed that POCA promotes the dissolution of Pb2+ from the galena surface. The adsorption of POCA on the galena surface was confirmed through zeta potential testing, XPS testing, contact angle, AFM testing, and ToF-SIMS analysis, it was noted that POCA exhibited high levels of adsorption on the galena surface. Density Functional Theory (DFT) calculations suggest that the chemical interaction between the sulfonic acid present in POCA and the Pb2+ active site of galena is regarded as the primary inhibition mechanism.