Selective separation of fluorite from dolomite using cupferron: flotation performance and surface chemistry investigations

Abstract

Fluorite and dolomite are difficult to separate due to their similar surface properties, as both are calcium-bearing minerals. In this study, the performance of cupferron as a collector for the selective flotation of fluorite and dolomite was compared with that of the conventional collector sodium oleate (NaOL) in the absence of depressants. Flotation experiments revealed that cupferron exhibits excellent selectivity for fluorite, whereas NaOL shows strong but non-selective collecting ability for both minerals. To elucidate the adsorption mechanism, various characterization techniques including contact angle measurements, FTIR, SEM, zeta potential analysis, XPS, and density functional theory (DFT) calculations were employed. Both collectors interact chemically with mineral surfaces; however, cupferron demonstrates significantly stronger and more selective binding to fluorite via Ca–O coordination, forming a stable five-membered chelate ring involving its N–O functional groups. In contrast, NaOL shows comparable chemical affinity to both fluorite and dolomite surfaces, leading to poor selectivity. The calculated adsorption energy of cupferron on fluorite is much more favorable than that on dolomite, consistent with the experimental findings. These results provide valuable insights into the selective flotation mechanism of cupferron and demonstrate its potential as an efficient collector for fluorite–dolomite separation.