Enhanced selectivity in Scheelite-Calcite flotation using oleic and palmitic acid mixed collectors: experimental and molecular dynamics insights

Abstract

The flotation separation of scheelite from calcite remains a significant challenge in mineral processing due to their similar surface characteristics. The present study proposes a novel approach using a 1:1 mixture of oleic acid and palmitic acid as a mixed collector to achieve effective separation. The mixed collector system enriched the WO3 content from 0.19% in the feed to 2.2% in the float fraction, with an overall recovery of approximately 81.2% in a single flotation stage. In comparison, calcite recovery was as low as 26.8%, supporting the scheelite selectivity of the mixed collector system. Additionally, the flotation mechanism, involving the interaction between collector species and mineral surfaces, was investigated using Fourier transform infrared spectroscopy, UV-vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. The results revealed that adsorption under the mixed collector system facilitated the formation of a greater number of Ca-carboxylate complexes on the scheelite surface than on calcite, indicating preferential adsorption on scheelite. Moreover, the molecular dynamics simulation results suggested that the mixed collector system exhibited the maximum water-displacing ability and the highest accumulation of collector molecules on the scheelite (1 1 2) surface, compared to both collectors used individually.