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

Flotation is the most common approach to obtaining concentrate through the selective adsorption of collectors on target minerals. In the hydrometallurgy of concentrate, adsorbed collectors can damage ion-exchange resin and increase the chemical oxygen demand (COD) value of wastewater. Thus, adsorbed collectors must be desorbed before metallurgy and reused in flotation. Lead nitrate and benzohydroxamic acid (Pb-BHA) complex collector is a common collector in scheelite flotation. In this study, different physical (stirring or ultrasonic vibration) and chemical (acid or alkali) 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 adsorbed on the scheelite concentrate surfaces were 90.48% and 63.75%, respectively. Real-ore flotation tests revealed that the reuse of desorbed Pb-BHA collector reduced the collector cost by 30% for BHA and 25% for Pb. The cavitation effect of ultrasonic waves effectively reduced the interaction intensity between Pb-BHA collector and scheelite surfaces. Meanwhile, solution chemistry calculations revealed that the strong alkali environment broke the chemical bonds between Pb and BHA. This method combining desorption and reuse can reduce collector costs for beneficiation plants and provide clean scheelite concentrate for smelting plants.