Study on the effects of pre-conditioning time on the floatability of molybdenite from the perspective of cavitation threshold

•A novel acoustic method was put forward to represent the wettability of particles in water.•The recovery and rate of molybdenite were dramatically decreased after long-time stirring or ultrasonic treatment.•The surface chemical properties seldom changed after long pre-conditioning time.•The molybdenite particles required some time to be completely wetted in water. In flotation processes, mineral particles are separated based on different surface physicochemical properties. The surface of molybdenite consists of both hydrophobic and hydrophilic faces, meaning this particular structure can lead to a reduction in floatability when molybdenite is treated using long-time stirring and ultrasound. In this study, an acoustic method called high-intensity focused ultrasound was applied to detect the nuclei in a molybdenite suspension before and after long-duration pre-conditioning. The cavitation threshold (liquid pressure at 50% cavitation probability) was then calculated based on numerous cavitation results, which were applied to characterize the wettability of molybdenite particles in water. Additionally, particle size measurements and X-ray photoelectron spectroscopy analysis were employed to highlight the differences in particle properties after long-duration pre-conditioning. However, these tests cannot fully elucidate the changes in floatability of molybdenite in water. Nano-bubbles on particle surfaces were determined to be the main cause for the high floatability of molybdenite. This study will present insights into the vital role of pretreatment time on the floatability of molybdenite. We also propose a method for determining the wettability of particles in water.