Using ML8 to achieve the lime-free separation of sphalerite-pyrrhotite under the copper activation system

Abstract

Sphalerite flotation is conducted under Cu2+ activation system, whereas the selective separation of pyrrhotite is difficult due to the inevitable activation effect of Cu2+, which requires a large amount of lime to depress pyrrhotite flotation. In this study, the conventional collector butyl xanthate and a novel collector ML8 were compared to the selectivity of the flotation separation of sphalerite and pyrrhotite. The ML8 was investigated as an effective sphalerite collector to achieve the lime-free separation of sphalerite and pyrrhotite. Single mineral flotation indicated that sphalerite exhibited good floatability under low-alkaline conditions, whereas pyrrhotite was almost non-floatable, and their selective separation could be achieved using a low dosage of ML8. Mixed mineral flotation further confirmed that the ZnS separation could be achieved under low-alkaline conditions (pH = 9) using ML8 as a sphalerite collector. Reagents adsorption measurements demonstrated that ML8 possessed greater affinity to sphalerite than pyrrhotite, thus the contact angle of sphalerite increased from 51° to 76° after treatment with ML8 while that of pyrrhotite only increased from 67° to 70°. XPS detection results illustrated that the adsorption sites of ML8 on sphalerite were the adsorbed Cu site on the mineral surface rather than the Zn site of sphalerite crystal. The amount of Cu sites located on sphalerite was much greater than on pyrrhotite after the activation with copper sulfate.