High-gradient magnetic separation mechanism for separation of chalcopyrite from molybdenite

Removing molybdenite from chalcopyrite by flotation has long been a challenge due to their similar floatability as sulfide minerals. However, the difference in the magnetic susceptibility of the two minerals may be employed to address this challenge. Recently, pulsating high-gradient magnetic separation (PHGMS) has been reported effective as an environmentally friendly and economical strategy for separating chalcopyrite from molybdenite, but the mechanism of their magnetic differences is unclear. The current investigation employed crystal field theory and density functional theory calculations to theoretically elucidate the magnetic properties of these two minerals, and their difference was further demonstrated by experimental investigations. Under optimized conditions in a SLon-100 cyclic PHGMS separator, a chalcopyrite concentrate assaying 31.47% Cu and 0.44% Mo at 81.93% Cu and 5.56% Mo recoveries was produced from a pure chalcopyrite-molybdenite mixture that initially contained 26.29% Cu and 5.42% Mo. After the separation process, the Cu grade decreased to 15.06%, whereas the Mo grade increased to 16.22% in the nonmagnetic product. These findings have potential implications for the separation of chalcopyrite from molybdenite using PHGMS.