Enhancement of Phosphate Flotation by Ultrasonic Pretreatment

Removal of carbonate impurities in sedimentary phosphate is one of the most important issues in the industry. Poor selective flotation of those ores is due to the similarity of Physico-chemical surface properties, solubility, and electrokinetic characteristics of sparingly soluble phosphate and carbonate minerals. In this study, the effect of ultrasonic irradiation as a pretreatment method on reverse flotation of low-grade sedimentary phosphate sample from Lar Mountain deposit was investigated. Ultrasonic was utilized before flotation at different ultrasound intensity. This study was performed by two flotation approaches; i) using experimental design (Plackett-Burman method with 11 variables), and ii) try and error method. Initial mineralogical studies showed that the feed sample contains 10.34%P2O5, 48.01%CaO, and 9.22%SiO2. The collected data from experimental design were analyzed by DX7.0 software to assess the influence of each parameter on flotation performance. The results indicated that ultrasound intensity, collector dosage, and dispersant dosage were the effective parameters. The results of the try and error method showed that the conditioning time was the most effective parameter in which by reducing ultrasonic preparation time the recovery was increased relative to 33.29%. Finally, the kinetic flotation tests and SEM studies were performed. The results proved surface cleaning of phosphate minerals which treated by ultrasound irradiation that led to better adsorption of chemicals which increased the recovery and grade of P2O5 for 87.88% and 14.45%, respectively. However, the application of the ultrasonic treatment reduced the flotation chemicals’ consumption which is a prominent issue for phosphate treatment.