Experimental, benchmarks and theoretical investigations into the complexation of chalcopyrite and silica with guar gum and beneficiation of a siliceous copper ore using polyethylene oxide as a silica depressant

Abstract

The application of guar gum (GG) as a selective chalcopyrite flocculant on Mpanda Mineral Field (MMF) ore and flotation of flocculated fraction in presence of polyethylene oxide (PEO) as a silica depressant was investigated. For the first time theoretical simulation of FTIR for GG was conducted and interestingly it was noted to match with the experimental one. Different functionals were used to optmise the complexes and it was noticed that MN15/6-311++gdp/def2-TZVP perfomed best compared to other tested functionals with respect to rev-DSD-PBEP86-D3(BJ), a double hybrid functional as reference, with a mean absolute % deviation in complexation energy of 1.4 %. The complexation energy for GG with Cu species was higher than that of Fe and S species on chalcopyrite surface suggesting that GG adsorbs more on Cu sites compared to others. Further, the complexation energy for Silica-GG dimer was lower relative to chalcopyrite-GG dimer and this is in agreement with experimental results. The resulting nature of interaction in chalcopyrite-GG complex was found to be conventional hydrogen bonding (HB), non-covalent and partial covalent interaction, whereas that for silica-GG dimer was HB only. After selective flocculation, the settled fraction was subjected to flotation in presence of 60 g/t of potassium amyl xanthate and 500 g/t of PEO, as collector and silica depressant, respectively, and yielded Cu grade and recovery of 28.4 % and 93.2 % respectively.