Selective adsorption of eco-friendly inhibitor sesbania gum on dolomite for efficient flotation separation of magnesite and dolomite

The flotation separation of magnesite and dolomite poses significant challenges due to their highly similar crystal structures and surface physicochemical properties. To address the challenge of green and efficient decalcification and purification of low-grade magnesite resources, this study employed sesbania gum (SG) as an inhibitor in a flotation system with sodium oleate (NaOl) as the collector, achieving the flotation separation of magnesite from dolomite. Micro-flotation test results showed that in the NaOl system, SG exhibited a significant selective inhibitory effect on the flotation of dolomite, while it had almost no effect on the flotation of magnesite. At a pH of 10.0, the reagent scheme of 30 mg/L SG and 120 mg/L NaOl effectively achieved the flotation separation of the two minerals. This study elucidated the selective inhibition mechanism of SG on dolomite through zeta potential measurements, Fourier transform infrared spectroscopy (FTIR), surface wettability analysis, and X-ray photoelectron spectroscopy (XPS). The results of zeta potential measurements, FTIR spectroscopy, and surface wettability analysis indicated that SG exhibited very weak adsorption on the surface of magnesite, but strongly adsorbed onto the surface of dolomite, significantly hindering the adsorption of NaOl on dolomite. This resulted in a marked difference in the flotation behavior of the two minerals. XPS analysis revealed that the active hydroxyl groups in the polysaccharide structure of SG have a strong interaction with calcium sites, while exhibiting very low affinity for magnesium sites. Compared with traditional inhibitors, SG offers the advantages of being non-toxic, readily available, and biodegradable. The application of SG can substantially reduce environmental pollution in mineral processing, meeting global demands for greener practices in mineral beneficiation. Additionally, SG use enhances the sustainability and environmental compatibility of flotation production.