Quantitative synergistic adsorption affinity of Ca(II) and sodium oleate to predict the surface reactivity of hematite and quartz

• Quantitatively revealed the coordination mechanism of Ca ions and sodium oleate. • Calculated the binding constants of Ca on hematite and quartz surfaces. • SCM describing the synergistic adsorption of Ca and NaOL on quartz and hematite was developed. • The surface reactivity of hematite and quartz was successfully predicted. The combination of metal ions and organic collectors has been widely utilized in mineral separation processes, however, there is a poor quantitative understanding of their adsorption mechanisms and effects. Although various surface complexation models have been established, the absence of metal ions and organic reagents affinity constant of oxidized ore impedes the prediction of metal ion-organic reagent adsorption behavior of minerals in the flotation process. The objective of this work is to develop the surface complexation model (SCM) for the ternary system hematite/quartz-Ca-sodium oleate. The results indicate that the binding of Ca on the surface sites of hematite and quartz was mainly dominated by monodentate adsorption ( ≡ Fe OCaOH and ≡ S i OCaOH ), corresponding to adsorption constants (logK) of 6.03 and 6.80, indicating that Ca ions are more readily adsorbed on the quartz surface. Furthermore, the binding constant of ≡ SiOCaOL site was 16.28, that of ≡ SiOHCa (OL ) 2 site was 21.70, that of ≡ FeOCaOL site was 14.96, and that of ≡ FeOHCa (OL ) 2 site was 20.64, demonstrating a strong synergistic interaction between Ca ions and NaOL from a quantitative perspective. Based on these adsorption affinity constants, the surface reactivity of quartz and hematite were successfully predicted from both different NaOL concentrations and slurry pH values. This finding provides insight into the mobility and coordination of Ca(II) and NaOL in solution and provides a method to quantify the adsorption behavior of metal-based collectors in multi-mineral systems.