Adsorption mechanism of efficient flotation separation of scheelite from calcite by a novel mixed collector

Abstract The separation of scheelite and calcite is a challenging problem in flotation production. In this study, the effects and mechanisms of oxidized paraffin soap (OPS) and octylphenol polyoxyxyethylene ether with 10 oxyethylene glycol ethers (OP-10) as a mixed collector to collect scheelite from calcite were surveyed by micro-flotation, Fourier transform infrared spectroscopy (FT-IR), surface tension tests, ultraviolet (UV) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The flotation results showed that the recovery of scheelite increased from 57.59% of 50 mg/L OPS to 94.75% of 30 mg/L OPS/OP-10 at pH 8, which proved that OP-10 could reduce the dosage of the OPS, and OPS/OP-10 was suitable for natural pH pulp. The surface tension tests demonstrated that OP-10 reduced the CMC of OPS aqueous solution and enhanced its solubilization. FT-IR analysis confirmed that OPS and OPS/OP-10 had strong chemisorption on the surface of scheelite and calcite. UV analysis further indicated preferential adsorption of OPS compared with OP-10, and the adsorption mechanism of the mixed collector can be confirmed as a co-adsorption. XPS analysis showed that OPS was chemically adsorbed on Ca sites on the scheelite surface, while the characteristic peak of the mixed collector did not shift significantly compared with that of OPS, indicating that OP-10 played a synergistic role mainly by co-adsorbing with OPS on the surface of scheelite. In a word, the mixed collector OPS/OP-10 was utilized for scheelite separation with satisfactory outcomes and exhibited an extensive prospect in scheelite production.