Efficient desorption and reuse of collector from the flotation concentrate: A case study of scheelite

Flotation is the most common method to obtain concentrate through the selective adsorption of collectors on target minerals to make them hydrophobic and floatable. In the hydrometallurgy of concentrate, collectors adsorbed on concentrate can damage ion-exchange resin and increase the chemical oxygen demand (COD) value of wastewater. In this work, we proposed a new scheme, i.e., desorbing the collectors from concentrate in ore dressing plant and reusing them in flotation flowsheet. Lead nitrate and benzohydroxamic acid (Pb-BHA) complex is a common collector in scheelite flotation. In this study, different physical (stirring or ultrasonic waves) and chemical (strong acid or alkali environment) methods for facilitating the desorption of Pb-BHA collector from scheelite concentrate were explored. Single-mineral desorption tests showed that under the condition of pulp pH 13 and ultrasonic treatment for 15 min, the highest desorption rates of Pb and BHA from the scheelite concentrate were 90.48% and 63.75%, respectively. Run-of-mine ore flotation tests revealed that the reuse of desorbed Pb and BHA reduced the collector dosage by 30% for BHA and 25% for Pb. The strong alkali environment broke the chemical bonds between Pb and BHA. The cavitation effect of ultrasonic waves effectively reduced the interaction intensity between Pb-BHA collector and scheelite surfaces. This method combining ultrasonic waves and strong alkali environment can effectively desorb the collectors from concentrate and provide “clean” scheelite concentrate for metallurgic plants; the reuse of desorbed collector in flotation flowsheet can reduce reagent cost for ore dressing plants.