Transactions of Nonferrous Metals Society of China (中国有色金属学报)•2026•DOI: 10.1016/S1003-6326(26)67066-5
Oxidation roasting of bastnaesite was conducted to evaluate its impact on surface characteristics and flotation behavior. Experiments varied temperature, time, and O2 concentration. Increasing temperature promoted thermal decomposition, yielding Ce7O12, RE2O3, and REF3 as main phases. The Ce oxidation degree and REO grade of roasted products exceeded 85.00%. Roasting induced long, narrow, nearly parallel cracks within particles, increasing porosity and causing partial fragmentation. During flotation, dissolved rare earth ion concentration increased significantly, and surface hydrolysis formed rare earth hydroxyl compounds. Complete decomposition raised the required collector dosage to achieve recovery above 85.00%. This increase is attributed to enhanced particle wettability, altered collector adsorption, and deeper penetration into the porous structure. The findings provide a basis for optimizing flotation circuits treating roasted bastnaesite, particularly in iron-bearing rare earth deposits where pyrometallurgical pretreatment is employed.
Int. Journal of Mining Science and Technology (采矿与安全工程)•2026•DOI: 10.1016/j.ijmst.2026.01.002
To address the deviation between rigid confining pressure experiments and actual engineering conditions of deep backfill mining, where backfill near the working face has less confining pressure, while that in deep goaf areas is under high confining pressure, this study investigates the load-bearing characteristics of rock granular materials under flexible passive confining pressure. Customized PC molds with varying wall thicknesses and rigid steel molds were used to construct a gradient confining pressure environment. Compression tests were conducted, combined with the characterization of acoustic emission (AE) monitoring, strain measurement, particle sieving, and scanning electron microscopy (SEM) observation. The results show that flexible passive confining pressure divides the particle compression process into three stages that are different from those under traditional rigid constraints, namely the initial compaction stage, the crushing failure stage, and the lateral confinement-dominated stage. AE signals exhibit a bimodal energy distribution, and the time interval between the two can vary by more than 4 times with changes. The failure modes transition from shear to tension. Compared with intact materials, granular materials under lateral confinement maintain continuous volume contraction, and can even maintain a continuous volume contraction trend at least when the strain reaches 8%. And lateral confinement stiffness significantly enhances axial bearing capacity: when the axial strain reaches 30%, the axial stress in the rigid confinement group is nearly 5 times that in the flexible confinement group. Fractal dimension increases from 1.94 to 2.39 as the confinement stiffness rises. This study clarifies the influence mechanism of lateral confinement stiffness on granular mechanics, providing fundamental support for optimizing backfill design based on goaf locations and improving surrounding rock control in deep green mining.
Journal of Central South University•2026•DOI: 10.1007/s11771-026-6266-6
To reduce the subjectivity of conventional instability criteria in deep rock engineering, this study develops an energy-driven criterion grounded in cusp catastrophe theory and embeds it within an improved nonlinear Hoek-Brown (H-B) strength-reduction framework. We derive an explicit algebraic transformation that maps a quartic energy potential to the standard cusp form and introduce the mutation eigenvalue Δ as a physically interpretable measure of proximity to the vanishing of the energy barrier. Building on this, failure staging is diagnosed in practice by the concurrence of a slope mutation in displacement-reduction-factor curves, a threshold jump of total plastic strain-energy increment typically exceeding threefold between adjacent reduction steps, and video-confirmed crack through-connection. Integrating Δ with the nonlinear reduction scheme yields reproducible integral safety factors. Two representative cavern layouts (Model A/B) are validated by scaled physical model tests and companion simulations: global failure occurs at the overload safety factor K=2.33 for Model A and K=2.73 for Model B, with relative deviations from tests (2.4P0 and 2.9P0) of 1.3% and −5.9%, respectively, coinciding with the energy-jump threshold and the multi-evidence diagnosis. Compared with the equivalent Mohr-Coulomb parameter approach, the improved nonlinear scheme produces smaller (more conservative) safety factors by 5.7% and 2.5%, while better matching the observed destabilization process. The framework clarifies the role of Δ as an energy-based instability indicator and offers a practical, verifiable criterion for cavern stability assessment.
Nano-Micro Letters•2025•DOI: 10.1007/s40820-025-01817-x
Organic–inorganic hybrid perovskite solar cells achieve remarkable efficiencies (> 26%) yet face stability challenges. Quasi-2D alternating-cation-interlayer perovskites offer enhanced stability through hydrophobic spacer cations but suffer from vertical phase segregation and buried interface defects. Herein, we introduce dicyanodiamide (DCD) to simultaneously address these dual limitations in GA(MA)nPbnI3n+1 perovskites. The guanidine group in DCD passivates undercoordinated Pb2+ and MA+ vacancies at the perovskite/TiO2 interface, while cyano groups eliminate oxygen vacancies in TiO2 via Ti4+–CN coordination, reducing interfacial trap density by 73% with respect to the control sample. In addition, DCD regulates crystallization kinetics, suppressing low-n-phase aggregation and promoting vertical alignment of high-n phases, which benefit for carrier transport. This dual-functional modification enhances charge transport and stabilizes energy-level alignment. The optimized devices achieve a record power conversion efficiency of 21.54% (vs. 19.05% control) and retain 94% initial efficiency after 1200 h, outperforming unmodified counterparts (84% retention). Combining defect passivation with phase homogenization, this work establishes a molecular bridge strategy to decouple stability-efficiency trade-offs in low-dimensional perovskites, providing a universal framework for interface engineering in high-performance optoelectronics.
Nano-Micro Letters•2025•DOI: 10.1007/s40820-025-01782-5
Rechargeable zinc-ion batteries have emerged as one of the most promising candidates for large-scale energy storage applications due to their high safety and low cost. However, the use of Zn metal in batteries suffers from many severe issues, including dendrite growth and parasitic reactions, which often lead to short cycle lives. Herein, we propose the construction of functional organic interfacial layers (OIL) on the Zn metal anodes to address these challenges. Through a well-designed organic-assist pre-construction process, a densely packed artificial layer featuring the immobilized zwitterionic molecular brush can be constructed, which can not only efficiently facilitate the smooth Zn plating and stripping, but also introduce a stable environment for battery reactions. Through density functional theory calculations and experimental characterizations, we verify that the immobilized organic propane sulfonate on Zn anodes can significantly lower the energy barrier and increase the kinetics of Zn2+ transport. Thus, the Zn metal anode with the functional OIL can significantly improve the cycle life of the symmetric cell to over 3500 h stable operation. When paired with the H2V3O8 cathode, the aqueous Zn-ion full cells can be continuously cycled over 7000 cycles, marking an important milestone for Zn anode development for potential industrial applications.
Int. Journal of Mining Science and Technology (采矿与安全工程)•2025•DOI: 10.1016/j.ijmst.2025.02.006
Understanding the anchorage performance of en-echelon joints under cyclic shear loading is crucial for optimizing support strategies in jointed rock masses. This study examines the anchorage effects on en-echelon joints with various orientations using laboratory cyclic shear tests. By comparing unbolted and bolted en-echelon joints, we analyze shear zone damage, shear properties, dilatancy, energy absorption, and acoustic emission characteristics to evaluate anchoring effects across shear cycles and joint orientations. Results reveal that bolted en-echelon joints experience more severe shear zone damage after cycles, with bolt deformation correlating to shear zone width. Bolted en-echelon joints exhibit faster shear strength deterioration and higher cumulative strength loss compared to unbolted ones, with losses ranging from 20.04% to 72.76%. The compressibility of en-echelon joints reduces the anchoring effect during shear cycles, leading to lower shear strength of bolted en-echelon joints in later stages of shear cycles compared to unbolted ones. Bolts reinforce en-echelon joints more effectively at non-positive angles, with the best performance observed at 0° and –60°. Anchorage accelerates the transition from rolling friction to sliding friction in the shear zone, enhancing energy absorption, which is crucial for rock projects under dynamic shear loading. Additionally, rock bolts expedite the transition of the cumulative AE hits and cumulative AE energy curves from rapid to steady growth, indicating that strong bolt-rock interactions accelerate crack initiation, propagation, and energy release.
Int. Journal of Mining Science and Technology (采矿与安全工程)•2025•DOI: 10.1016/j.ijmst.2025.09.011
Hydrate-based gas separation offers a promising approach for coalbed methane recovery, reaching energy conservation and emissions reduction. This study innovatively applied high-gravity technology to enhance hydrate formation in separating 25%CH4/67%N2/8% O2 for achieving rapid and efficient methane recovery. Systematic investigations were conducted at 283.2 K and 3.0 MPa with tetrahydrofuran at a molar concentration of 5.56% and L-tryptophan at a mass concentration of 0.5% additives, first evaluating liquid flow rate effects (0–20 mL/min) on mixed hydrate kinetic performance and separation efficiency, followed by rotating speed optimization (0–1200 r min−1) under the optimal liquid flow rate. The high-gravity system amplified the gas–liquid contact area by ∼1155 times through cascaded liquid supply and secondary shear effects, methane molecules entered the hydrate phase rapidly under the highest driving force with the significantly intensified mass transfer. Optimal conditions (20 mL/min, 600 r min−1) yielded an exceptional initial hydrate growth rate of 58.59 mmol/(mol h) and methane recovery of 50.76%, about 71.33 and 0.58 times higher than the static system, respectively. Gas chromatography and Raman spectrometer analyses revealed superior methane enrichment in hydrate phase at 90% gas uptake completion, with a concurrent 41.17% reduction in process duration. These findings demonstrate the efficacy of high-gravity-enhanced hydrate technology for coalbed methane separation, offering valuable insights for optimizing clean energy utilization.
Int. Journal of Mining Science and Technology (采矿与安全工程)•2024•DOI: 10.1016/j.ijmst.2024.12.006
The storage of solid waste in Bayan Obo has resulted in significant resource wastage and environmental concerns. In this study, an efficient process was developed to recover iron and rare earth elements (REEs) from this waste by processes of hydrogen-based mineral phase transformation (HMPT), magnetic separation, and flotation. Under optimal HMPT conditions (525 °C, 12.5 min, and 30% H2 concentration), an iron concentrate with a TFe grade of 64.09% and a recovery of 95.33% was obtained. The magnetic properties of the solid waste were greatly enhanced by HMPT, allowing the effective magnetic separation of iron minerals. Further optimization of the flotation process resulted in a REEs concentrate with a rare earth oxide (REO) grade of 65%–70% and a REEs recovery of 60%–65%. Hematite was reduced to magnetite during HMPT, and bastnaesite was decomposed to REEs oxides and fluorides, and the particle structure was significantly destroyed. However, changes in monazite, fluorite, and barite were minimal.