Strengthening effect of a microwave field on sulfurization flotation of hemimorphite

Hemimorphite is a typical silicate zinc oxide mineral characterized by strong hydrophilicity and poor floatability. It is commonly recovered by the “sulfurization pretreatment-xanthate collector flotation” method. However, the Zn²⁺ in hemimorphite is blocked by SiO₄^2-, making Zn-O bonds difficult to break and preventing the reaction between Zn²⁺ and S^2- in solution. Therefore, enhancing sulfurization is essential for the flotation of hemimorphite. In this study, a microwave field was used for the first time to increase the surface sulfurization of hemimorphite, and the interactions between the minerals and collectors were increased by forming a sulfurization layer on the mineral surface to improve hemimorphite flotation. Compared with the conventional sulfurization pretreatment, microwave field sulfurization pretreatment exhibited better floatability under the same conditions, and the recovery reached 29.82%, which was much higher than that without microwave treatment. The mechanism of hemimorphite sulfurization in the microwave field was investigated with infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. These results indicated that the microwave field enhanced the surface sulfurization of hemimorphite, and increased the proportions of newly generated sulfides, thus boosting sulfurization flotation of hemimorphite.