Impact of NaOL as an accelerator on the selective separation of scheelite from fluorite using a novel self-assembled Pb-BHA-NaOL collector system

Abstract

Strategic Ca-bearing minerals such as scheelite and fluorite are usually separated by flotation; however, their separation is quite difficult due to the similarity of the Ca active sites on their surfaces. Lead nitrate-benzohydroxamic acid (Pb-BHA) mixtures show better selectivity for scheelite than the conventional strong collector sodium oleate (NaOL), but their high cost hinders their wide application. Therefore, in this work, a novel collector system (Pb-BHA-NaOL) was developed to overcome the above-mentioned drawback. Flotation results using a single mineral and real ore showed that Pb-BHA-NaOL had better selectivity for scheelite than Pb-BHA. When Pb, BHA, and NaOL were sequentially assembled in a 240:120:1 molar ratio at pH 9.0, the selective separation of scheelite from fluorite was successfully achieved without adding depressants. Additionally, the same scheelite recovery could be achieved while using 20% less Pb and BHA by employing the Pb-BHA-NaOL system rather than the Pb-BHA system. Through zeta potential measurements, solution chemistry calculations, and X-ray photoelectron spectroscopy, the major role of the selective chemical adsorption of Pb-BHA+, Pb-BHA-OL, and Pb(OH)-BHA-OL− on the surface of scheelite in the separation of scheelite from fluorite was revealed, along with the role of NaOL as an accelerator to improve the adsorption modes and capacities of Pb and BHA on scheelite.