Hao Zhang

Nanomaterials offer high specific surface area and tunable surface chemistry. They can be used as promising adsorbents, photocatalysts, and membrane components for wastewater treatment. However, problems of low efficiency and low recyclability limit the practical application of some nanomaterials. This review summarizes their use for inorganic and organic pollutant removal and examines defects. The modification and controllable construction of nanomaterials in terms of defect regulation, pore structure modification, and surface modification are also summarized. Pore and surface engineering strategies are discussed through a structure–property–performance framework. Then, improvements in pore and surface structures are investigated in relation to the controllable construction of nanomaterials. The evidence indicates that performance gains must be evaluated alongside regeneration, active-material leaching, transformation products, and energy demand. Future progress depends on reproducible comparisons, realistic wastewater testing, and recovery-by-design rather than removal efficiency alone.

The efficient beneficiation of low-grade Cu–Ni sulfide ores is challenging because Cu-bearing and Ni-bearing sulfide minerals are finely intergrown with gangue minerals. In this study, the ore composition and mineral liberation characteristics were examined, and different flotation flowsheets were evaluated. A flotation feed containing 80% of particles finer than 0.074 mm was selected by balancing mineral liberation against the adverse effects of excessive fines. After flowsheet optimization, a partially preferential flotation strategy was adopted, in which most Cu was first recovered into a Cu concentrate, and the remaining Cu was recovered together with Ni in a Cu–Ni bulk concentrate. For the closed-circuit flowsheet, an economic Cu concentrate with a Cu grade of 20.65% and Cu recovery of 78.77%, and qualified Cu–Ni bulk concentrates with a Ni grade of 5.43% and Ni recovery of 61.99%, were obtained. The comprehensive recovery rate of Cu was 88%. Partially preferential flotation simplifies the separation flowsheet of Cu–Ni ores while achieving substantial recovery of valuable metals. The technology is highly efficient and economical, and has broad application prospects for the beneficiation of low-grade Cu–Ni sulfide ores.

For effective removal and utilization of fluorine resources from industrial wastewater, stepwise removal and recovery of fluorine were accomplished by seeding crystallization and flotation. The effects of seedings on the growth and morphology of CaF₂ crystals were investigated by comparing the processes of chemical precipitation and seeding crystallization. The morphologies of the precipitates were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM) measurements. The seed crystal, fluorite, helps improve the growth of perfect CaF₂ crystals. The solution and interfacial behaviors of the ions were calculated by molecular simulations. The existing perfect surface of fluorite was proven to provide the active sites for ion adhesion and formed a more ordered attachment layer than the precipitation procedure. The precipitates were then floated to recover calcium fluoride. By stepwise seeding crystallization and flotation, the products with a CaF₂ purity of 64.42% can be used to replace parts of metallurgical-grade fluorite. Both removal of fluorine from wastewater and the reutilization of the fluorine resource were realized.

Hemimorphite and smithsonite are all-important zinc oxide minerals. The beneficiation and separation of them using flotation method is usually considered difficultly. Minerals surface wettability and its regulation are the core issues in the flotation process, which closely correlate with the surface properties of the minerals. Therefore, an in-depth understanding of the surface properties of the two minerals is of great significance for the study of the flotation technology of them. In this study, the surface properties of the hemimorphite (110) surface and the simthsointe (101) surface, and their relationships to the mineral floatability have been investigated by first-principle calculation method based on density functional theory. The calculation results demonstrated that the hemimorphite (110) surface exhibited more obviously surface reconstruction. For the orbital energy level of the surface atoms of two minerals, the O 2p orbital is closer to the Fermi level than the Zn 3d. Chemical bond Mulliken population value indicated that the ionicity of the unsaturated linkage on the smithsonite (101) surface was stronger than that on the hemimorphite (110) surface. The absolute values of the ratios of negative charges to positive charges on the surfaces of hemimorphite and smithsonite were 1.529 and 1.256 respectively. These results implied that the O atoms on hemimorphite (110) surface are more impede collector molecule, such as hydroximic acid, bond with Zn atom, hemimorphite (110) surface is more readily wetted by water. This study provides comprehension at an atomic level to the relationship between surface properties and the floatability of hemimorphite and smithsonite.

Mechanical failures is most in all failures of circuit breaker. The mechanical reliability of circuit breaker is very crucial for power grid safety. In order to improve the mechanical reliability of circuit breaker, at the same time, in order to reduce costs and improve the competitiveness of products in the market, the mechanical reliability of circuit breaker needs to be studied. The dynamic behavior of circuit breaker is studied by computer simulation. Firstly, the circuit breaker is meshed by HyperMesh, then Ls-dyna is used to calculate the transmission of the circuit breaker. After the calculation is completed, the results are checked by experiment. Optimize the circuit breaker structure according to the result.