A novel metal–organic complex surfactant for high-efficiency mineral flotation

Abstract The separation of scheelite from other calcium-containing minerals via flotation is problematic because of their similar surface properties and response to conventional anionic collectors. Herein, we report, to the best of our knowledge, a new type of metal–organic complex collector prepared via self-assembly of benzohydroxamic acid (BHA) ligands and Pb(II). A new Pb(II) complex [Pb6L8(NO3)3]NO3 (HL = BHA) is synthesized using coordination reactions and structurally characterized using single-crystal X-ray diffraction. Further, its flotation behavior and adsorption mechanism at the solid–liquid–gas interface were investigated via flotation experiments, zeta potential, XPS, TOF–SIMS, AFM, SFG-VS, adsorption capacity, froth-stability testing, etc. The results show that the developed complex exhibited good collecting ability and absolute specificity for scheelite. The complex was chemically adsorbed on the scheelite surface by combining the lead functional group and oxygen atoms of scheelite to form multilayer adsorbents, rendering the scheelite particle surface strongly hydrophobic. The complex collector and frother assembly are co-adsorbed at the gas–liquid interface, which significantly reduced the solution surface tension, forming a stable foam layer. Therefore, selective flotation was achieved through the targeted adsorption at interfaces. A simplified flotation process for scheelite using complex collector has been successfully applied in industry, significantly improving the recovery of scheelite. This high selectivity makes metal–organic complex a novel and promising collector for high-efficiency mineral flotation and contributes to the efficient and clean development of mineral resources.