Strengthening of sulfidization flotation of hemimorphite via fluorine ion modification

Abstract Sulfidization flotation is the primary method for the commercial processing of zinc oxide minerals; however, hemimorphite cannot be effectively processed by this method because of the lack of sulfide active sites on its surface. In this paper, a promising method for increasing the number of sulfide active sites on the hemimorphite surface through surface modification with fluorine ions is proposed. Microflotation tests show that the floatability of fluorine ion-modified hemimorphite was superior to that of the bare hemimorphite in the presence of fluorine ions with a concentration of 5 × 10−5 mol/L. Furthermore, the recovery increased by 3–5%, while the activator (Na2S and Pb2+) dosage decreased by 11.1%. Moreover, the proposed method improved the separation index of hemimorphite and quartz and increased the grade and recovery of hemimorphite. The mechanism involves corrosion of the hemimorphite surface by fluorine ions, resulting in a reduction in the Si content of the hemimorphite surface and the exposure of the originally masked Zn. The exposed Zn exhibited strong reactivity toward vulcanizators to form ZnS; this generated the more hydrophobic species PbS, thereby facilitating the absorption of xanthate species onto the sulfurized mineral surface and enhancing its hydrophobicity.