Flotation Separation of Smithsonite from Calcite Using Cupferron as a Collector

The flotation separation of smithsonite and calcite is difficult due to their similar surface properties. In this study, cupferron was applied as a collector to realize the separation of smithsonite and calcite. Micro-flotation experiment results indicated that smithsonite and calcite express different floatability after treatment with cupferron. The maximum recovery difference was 63%, from a cupferron concentration of 2 x 10(-4) mol/L at pH 8. Based on a series of tests, including an adsorption test, Fourier-transform infrared (FTIR), zeta potential and X-ray photoelectron spectroscopy (XPS), the selective collection mechanism of cupferron was studied. It was found that the cupferron was more easily adsorbed on the surface of smithsonite and the reaction was violent. The adsorption capacity of the cupferron on the surface of smithsonite was higher than that of calcite, and the surface potential shift was greater. The cupferron chelated with the exposed Zn sites on the smithsonite surface to form a N-O-Zn ring structure. This special chelate structure caused the smithsonite surface to be more hydrophobic, which confirmed that the cupferron can selectively collect smithsonite instead of calcite.