Search

In the research on sustainable mining and environmental preservation, understanding the dynamic behaviour of rock formations in deep, high-stress mining environments is essential. In order to acquire the laws of rock dynamic disaster generation from mining in deep, high-stress environments, this research adopts a multistage and multi-cycle triaxial cyclic loading test to obtain the stress–strain curves and macroscopic deformation characteristics of hard sandstone under different surrounding pressures. The results show that the cumulative damage displacement of hard sandstone under cyclic loading at a certain stress level for the first 3–4 cycles is half of the total damage displacement at that cycle stage, and its peak volumetric strain will increase with the increase. The elastic energy density ratio and dissipation energy density ratio of hard sandstone under cyclic loading show a sinusoidal fluctuation trend, and the fluctuation gradually decreases with the increase in the number of cycles and the increase in the cyclic stress level. Under the cyclic loading of different surrounding pressures, the hard sandstone shows brittle damage characteristics, where the damage form is mainly shear damage with a small amount of tensile damage in low surrounding pressure and the damage form is mainly shear damage, tensile damage, and local compression damage in high surrounding pressure. The study reveals the deformation and damage law, energy evolution, and dissipation characteristics of high-strength hard sandstone. It is essential for the development of mining strategies that minimize the impact on the environment, reduce the dynamic hazards generated by mining, and maximize the efficiency of resource extraction [ABSTRACT FROM AUTHOR]

Aiming at the problem of the low reuse rate of mine water due to the high content of heavy metals in mine water, in this research, the microcharacterization means of EDX, XRD, BET, SEM, and FT-IR were used to characterize the nonstick coal in a mine in western China. The effects of solid–liquid ratio, solution pH, solution temperature, adsorption time, and initial concentration of the solution on the adsorption of Fe(II) by the nonstick coal were analyzed. The adsorption performance of nonstick coal on adsorbed Fe(II) was analyzed under different influencing factors. The results showed that the adsorption capacity and unit removal rate of the coal samples gradually decreased with the increase in the solid–liquid ratio; the adsorption amount increased with the increase in pH in an "S" shape, and the adsorption effect was better in the range of pH = 5~7; and the adsorption amount increased linearly with the temperature. The quasi-secondary kinetic model and Langmuir model could fit the adsorption kinetic curve and isothermal adsorption curve better, which indicated that the adsorption of Fe(II) by the nonstick coal was dominated by the chemical adsorption of the monomolecular layer. The quantitative analysis of the FT-IR results showed that the adsorption of Fe(II) was mainly by complexation with -OH detached from the coal samples to produce precipitation. [ABSTRACT FROM AUTHOR]

In this paper, a reconfigurable all-dielectric metasurface based on Ge 2 Sb 2 Se 4 Te 1 (GSST) phase-change material is proposed. By changing GSST from amorphous state to crystalline state, the metasurface can achieve high circular dichroism (CD) and wideband polarization conversion for circularly polarized waves in the mid-infrared (MIR) band. The maximum CD value reaches 0.95 at 74 THz, and circular polarization conversion efficiency is more than 90% in the wideband range of 41 THz - 48 THz. In addition, based on Pancharatnam-Berry phase, three kinds of wavefront manipulation of light have been realized: abnormal refraction, orbital angular momentum vortex beam and orbital angular momentum vortex beam splitting. This work has potential applications in the future MIR optical integrated system.