In-depth analysis of surface selective adsorption and interfacial mechanisms in the efficient flotation separation of magnesite and dolomite with the environmentally friendly inhibitor baicalin

Abstract

Due to the similarities in crystal structure and chemical composition, the surface electric properties, wettability, and interfacial characteristics of magnesite and dolomite are highly similar, posing significant challenges in flotation separation. This study investigates the selective inhibition mechanism of the environmentally friendly depressant baicalin (BA) on dolomite in a sodium oleate (NaOl) flotation system, focusing on interfacial behavior control. Micro-flotation tests showed successful separation of magnesite and dolomite under optimal reagent conditions (pH 10.0, BA concentration of 60 mg/L, NaOl concentration of 120 mg/L). Zeta potential and contact angle measurements indicated that BA increased the negative charge on dolomite and significantly reduced its hydrophobicity, with minimal impact on magnesite. FTIR and XPS analyses revealed strong chemisorption of BA’s hydroxyl groups on calcium sites of dolomite, with weaker affinity for magnesium sites. AFM imaging showed a notable increase in the surface roughness of dolomite after BA treatment, further confirming selective adsorption. A flotation separation model was developed based on micro-flotation and characterization results, shedding light on the separation mechanism and the differences in surface adsorption and interfacial behavior of magnesite and dolomite.