A Study on the Effect of Ultrasound Irradiation as Pretreatment Method on Flotation of Sedimentary Phosphate Rock with Carbonate–Silicate Gangue

Abstract

This research aims to explore the effect of ultrasound irradiation as a pretreatment method on the reverse flotation of phosphates. Ultrasonic treatment was used prior to flotation at various ultrasound intensities. The feed sample containing 10.34% P2O5 and 48.01% CaO was obtained from Lar mountain located in southwest of Iran. Flotation experiments were performed using two approaches: (1) a 2-level fractional factorial design with six variables and (2) try and error method. The results of experimental design showed that depressant type and pH were the effective parameters. The collected data from try and error experiments indicated that the conditioning time was the most effective parameter on the recovery. (By reducing the conditioning time from 11 to 6 min, the recovery was increased from 65.93 to 87.88%.) Furthermore, surface cleaning of phosphate minerals treated by ultrasound waves was proved by kinetic analysis, semiquantitative analysis by XRD and SEM–EDX. It was concluded that efficiency of phosphate flotation using ultrasound irradiation due to the cavitation bubbles that led to clean surface of particles is higher compared to the conventional flotation. After a cleaner step, the final grade and recovery of P2O5 reached 21.31% and 77.18%, respectively.