New Insights into the Effect of Surface Chemical Properties on the Flotation Behavior of Dolomite: A New Interpretation from the Perspective of Mineral Crystal Structure

The adsorption behavior of flotation reagents on different crystal planes of minerals varies. Selective grinding can control the exposed crystal planes of minerals in flotation. In this study, the adsorption behavior of NaOL on the surface of three dolomites with different crystal structures was investigated. The microflotation test results showed that the recovery rates of the three dolomites (DO1, DO2, DO3) were 81.95%, 70.9%, and 86.75%, respectively, at a concentration of 1.2 × 10^–4 mol/L NaOL. The zeta potential and contact angle experiments confirmed that the adsorption of NaOL in DO3, DO1, and DO2 decreased successively. Atomic force microscopy (AFM) imaging demonstrated that NaOL was uniformly adsorbed on dolomite, and the adsorption density was positively correlated with the flotation recovery in monolayer adsorption. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) studies showed that Ca and Mg are the adsorption sites of NaOL, and the (104), (116), and (018) crystal planes are the main exposed surfaces of dolomite. Density functional theory (DFT) research indicated that the surface energy of (104) dolomite is the lowest, at 0.434 J/m². The O of water molecules close to the mineral surface will adsorb to metal ions on the dolomite surface, H will form hydrogen bonds with CO₃^2–, and the rest of the water molecules form clusters through hydrogen bonds. NaOL adsorbed on the surface of dolomite will repel the surrounding water and form a hydrophobic layer, and the crystal structure of dolomite has a great influence on the adsorption of NaOL. This study provides a theoretical basis for efficient flotation recovery of dolomite.