Molecular dynamics of the interaction between four metal oxides (ZnO, Fe₂O₃, Al₂O₃, and CaO) present in zinc-bearing dust sludge and choline chloride (ChCl)-malonic acid (MA)(1:2) was studied in this work using Materials Studio software. The interaction mechanism was revealed by analyzing the interaction energy and radial distribution function from the perspective of quantum mechanics, and the simulation results were verified by single factor leaching experiments. The calculation results show that the complete cleavage surface of the four metal oxides is the (001) surface, and ChCl-2MA forms a stable structure with multiple intermolecular hydrogen bonds centered on the chlorine atom. The dynamic simulation of the interaction model shows that strength of interaction between ChCl-2MA and the four metal oxides follows the order: ZnO > Fe₂O₃ > Al₂O₃ > CaO. ChCl-2MA mainly interacts with ZnO by chemical adsorption, while ChCl-2MA mainly interacts with Fe₂O₃, Al₂O₃, and CaO by physical adsorption. The radial distribution function shows that Cl in ChCl-2MA and C=O in MA form chemical bonds with Zn in ZnO, and the choline cation (Ch⁺) forms C-H···O with ZnO. Among these bonds, the Cl-Zn bond energy is stronger. During the interaction between ChCl-2MA and Fe₂O₃ and Al₂O₃, O-H···O and C-H···O are formed and interact with CaO by van der Waals force. Single factor leaching experiments show that, under the same leaching conditions, the leaching rate of ZnO by ChCl-2MA is greater than 90%, while the leaching rate of Fe₂O₃, Al₂O₃, and CaO is about 10%. These results indicate good selectivity of ChCl-2MA for ZnO in the zinc-bearing dust sludge. The above conclusions have important theoretical significance and provide an in-depth understanding of the leaching mechanisms of zinc-bearing dust sludge in deep eutectic solvents.

In order to improve the calculation efficiency of a discrete element EDEM (Discrete Element Method) numerical simulation software for micron particles, the particle model is linearly enlarged. At the same time, the parameters of the amplified particles were calibrated according to the Hertz-Mindlin with JKR (Johnson-Kendall-Roberts) contact model to make the amplified particles have the same particle flow characteristics as the actual particles. Actual tests were utilized to gather the angle of repose of the microfine iron tailings, which was then used as a reference value for response surface studies based on the JKR contact model from six factors connected to the fine iron tailings particles. The Plackett-Burman test was used to identify three parameters that had a significant effect on the rest angle: static friction factor; rolling friction factor; and JKR surface energy. The Box-Behnken experiment was used to establish a second-order regression model of the rest angle, and the significant parameters and the optimized parameters were: surface energy JKR coefficient 0.459; particle-particle static friction coefficient 0.393; and particle-particle dynamic friction coefficient 0.393, with a dynamic friction coefficient between particles of 0.106. By entering the parameters into the discrete element program, the angle of repose generated from the simulations was compared with the real test values, and the error was 1.56%. The contact parameters obtained can be used in the discrete element simulation of the amplified particles of fine-grained iron tailings, providing an EDEM model reference for the numerical simulation of fine-grained iron tailings particles. There is no discernible difference between the actual and simulated angles.

The recovery of zinc from metallurgical dust sludge is a crucial component of using solid waste as a resource in the metallurgical process, and deep eutectic solvent–ultrasonic synergistic enhanced leaching is an efficient method of doing so with excellent economic effects. The leaching rate of zinc is used as the value of response in this study, along with the four process conditions of leaching temperature, leaching time, liquid–solid ratio, and ultrasonic power. By building a regression model, the relationship between the various parameter components is investigated, and a strategy for optimization is then chosen and confirmed. The findings indicate that, for the parameters of temperature 40 °C, ultrasonic power 90 W, liquid–solid ratio 7:1 g/L, stirring speed 250 rpm, and leaching duration 80 min, the prediction value of the regression model of the zinc leaching rate is 98.47%. The average zinc leaching rate obtained by the 3 parallel verification experiments was 98.49%; the deviation from the regression model’s predicted value was 0.02%. This demonstrated that the experimental results were consistent with those predicted by the regression model, the experimental results were reliable and trustworthy, and the optimization scheme was reasonable and accurate. Compared with the conventional leaching method (leaching rate: 91.61%), the method under ultrasound increased the zinc leaching rate by 6.88%.

In this study, the zinc containing dust and sludge of iron and steel smelting was taken as the research object, and the new ionic liquid of choline-urea was prepared and synthesized as the leaching agent. The conventional and ultrasonic leaching of zinc were compared, and the influence of liquid-solid ratio, temperature, time, ultrasonic power and other conditions on the zinc leaching rate were analyzed. The leaching residue was characterized by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-ray diffraction (XRD), and the kinetic equations of ligand leaching based on ultrasonically enhanced metallurgical dust sludge were constructed. The results showed that the choline chloride-urea ionic liquid has a special solubilization ability for ZnO, and the leaching rate of Zn at temperature 60 °C, ultrasonic power 350 W, and leaching time 240 min reached more than 98%. Kinetic fitting of the ChCl-urea leaching process revealed that the ChCl-urea leaching process was in accordance with the nucleation contraction model under both conventional and ultrasonic conditions, and the leaching process was dominated by interfacial mass transfer and solid film layer diffusion control for the reactions, respectively. The activation energies were Ea₁ = 44.56 kJ/mol and Ea₂ = 23.06 kJ/mol.