Recovery of zinc from blast furnace dust via ultrasonic-enhanced crotonic acid leaching: Leaching kinetics and mechanism.

Blast furnace dust (BFD) represents a significant processing residue in the steel manufacturing. The clean and efficient utilization of BFD could not only alleviate zinc resource shortage but also hold great significance for the resource recycling of steel enterprises. This study investigated the behavior and kinetics of zinc leaching from BFD with crotonic acid as a novel reagent under ultrasonic conditions. Leaching experiments indicated that under the conditions of 240 W ultrasonic power, 1:8 g/mL solid-to-liquid (S/L) ratio, 1 mol/L crotonic acid concentration, 40 °C temperature, and 40 min, the ultrasonic leaching rates of zinc and iron were 92.79 % and 15.45 %. The leaching kinetic analysis demonstrated that the ultrasonic-assisted leaching process and the regular leaching process were governed by mixed control and chemical reaction control, respectively. The characterization analysis indicated that ultrasonic action could break the particle agglomerates into smaller fragments and create fissures. This enabled crotonic acid to react with BFD particles to a greater extent, thus facilitating the selective leaching of zinc. The results of Density Functional Theory (DFT) demonstrated that compared with FeO, crotonic acid was more prone to be adsorbed on the surface of ZnO. Additionally, it reacted with metal atoms through the oxygen atoms in the carboxyl group. The experimental outcomes provided conceptual guidance for achieving cost-effective extraction of zinc resources from BFD.