Based on sorting out all exploration contracts approved by the International Seabed Authority, progress in negotiations on exploitation regulations, and policy divergences among major countries, it is argued that controversies over deep-sea mining rules focus on environmental protection, benefit distribution, regulatory responsibilities and commercial feasibility. China has established a relatively complete resource layout in international seabed, and also solid technological foundation for deep-sea exploitation, yet still confronts with regulatory uncertainties, environmental pressure and constraints on commercialization. China shall actively participate in the formulation of international deep-sea mining rules, strengthen international cooperation, and coordinate resource security and ecological conservation, for promoting the commercial exploitation of deep-sea mineral resources.

To address the problems of high costs and significant risks associated with at-sea tests of a full-scale deep-sea tracked mining vehicle, as well as the difficulty of existing simulation platforms in balancing physical fidelity and computational real-time performance, a co-simulation platform was developed and validated based on Project Chrono and ROS 2. With Chrono as the physics solving core and ROS 2 as the communication framework, the platform integrates a soil contact model and the Morison hydrodynamic model. Validation results demonstrate that the error of the simulated initial sinkage relative to the theoretical value is 2.4%, and the tractive force-slip ratio curve yields a coefficient of determination (R²) of 0.98 when fitted with theoretical values. Under the optimal engineering mesh resolution, the Real-Time Factor (RTF) stabilizes between 1.2 and 1.5, meeting the requirements of hardware-in-the-loop testing. This platform is available foe secondary development and also boasts higher computational efficiency, making it superior to the  mainstream commercial softwares such as Adams and RecurDyn. Featuring both engineering-level physical fidelity and open-source extensibility, this platform provides a reliable virtual testing environment for the iteration of control algorithms and prior dynamic analysis of deep-sea mining equipment.

For the ecological risks of sediment plumes induced by deep-sea mining disturbances, a high-fidelity numerical simulation framework was developed based on the Navier-Stokes equations, integrating high-resolution 3D topography, seawater density stratification, unsteady tidal dynamics, and multi-scale circulation constraints. A typical seamount mining area southwest of the Canary Islands in the Atlantic Ocean was taken as the research subject, and the multi-stage coupled evolution mechanism of the plume from initial disturbance to long-range ocean current transport was revealed after Spearman data validation. The study found that, constrained by the complex seamount topography and the geostrophic deflection effect, the horizontal path of the plume deflects significantly and exhibits a rotational diffusion pattern, which prolongs the residence time of particulate matter in the local water body. Modulated by the flow-around dynamic field of the seamount and the rotational shear mechanism, the plume evolves from a near-field point source discharge into a far-field anisotropic stretching structure. Due to the inhibitory effect of the stable deep-sea density stratification, the plume spatially exhibits a hierarchical dilution pattern.

To address the challenge of freeze-thaw instability of rock slopes in alpine mining areas, the andesite from a slope in a mining area in Ngari of Xizang was taken as the research object. Through freeze-thaw cycle tests, uniaxial compression tests, and triaxial compression tests, the deterioration laws of the mechanical properties of freeze-thaw andesite under different confining pressures were obtained. The results show that with an increase in the number of freeze-thaw cycles, both the compressive strength and shear parameters of the andesite exhibit a decreasing trend, and the deterioration degree gradually increases. Under unconfined conditions, the failure mode of the andesite evolves from splitting failure to mixed splitting-shear failure with an increase in the number of freeze-thaw cycles, accompanied by an increase in cracks. When confining pressure is applied, it enhances the compressive capacity of the rock to a certain extent. As the confining pressure increases, the failure mode gradually transitions from brittle failure to shear-slip failure. After a higher number of freeze-thaw cycles, radial crack propagation develops, accompanied by obvious spalling phenomena.

Based on the existing removal routes of aluminum impurities during the recycling of spent lithium iron phosphate (LFP) batteries, the recycling process is divided into two major stages: removal of a large amount of aluminum via separation and sorting, and elimination of trace aluminum by hydrometallurgical process. This paper comprehensively reviews the advantages and disadvantages of various emerging technologies in terms of impurity removal efficiency, selectivity, residual aluminum content, economic performance and environmental impact. The future research trends are also prospected, for providing theoretical basis for the high-value utilization of spent LFP materials and green transformation of the industry.

The modification strategies of carbon-based electrodes applied in all-vanadium redox flow batteries (VRFBs) is reviewed, and the effects of various modification methods on improving battery performance are discussed, aiming to provide guidance for the future development of VRFB technology.

Based on the investigation of the current development trends of deep-sea mining technologies, and in combination with the analysis of domestic and international literature and patent hotspots, three key technological fields of deep-sea mining were identified: collection, lifting, and surface support. Based on the systematic sorting of the core technologies in different fields, a review on the domestic and international research progress is presented in 10 core technologies, including ore crushing, ore collection, mining vehicle traveling, long-distance vertical pipeline transportation, anti-clogging and emergency escape for lifting pipelines, pump-free mineral transportation, underwater acoustic communication, mineral processing, launch and recovery, as well as heave compensation. A multi-dimensional quantitative assessment was conducted on China’s advantages and disadvantages compared to the international level in the overall field of deep-sea mining and the three key technological fields of collection, lifting, and surface support. Comprehensive analysis indicates that at the current stage, the main shortcomings of China’s deep-sea mining technologies include the low efficiency of core equipment, insufficient long-term reliability, inadequate understanding of deep-sea environmental disturbance mechanisms, and the lack of integrated coordinated operation in at-sea tests. The global challenges of deep-sea mining technology are mainly manifested in dynamic coordinated control under multi-field coupling, flow assurance and equipment reliability in long-distance vertical transportation, and environmental constraints and plume control. In the future, it is advisable for China to focus on breaking through core technologies, strengthening environmental impact assessment and monitoring, and conducting integrated system at-sea tests, so as to move toward the more systematical, smarter and eco-friendly technology, laying a foundation for China’s future participation in deep-sea resource exploitation.

By reviewing the formulation process of the Draft Regulations on Exploitation of Mineral Resources in the Area (short for the “Exploitation Regulations”) by the International Seabed Authority (ISA) and the US policies and legislations to unilaterally advance deep-sea mining in the international seabed area (short for the “Area”), this paper analyzes the game landscape of international legal regimes governing deep-sea mining from multiple perspectives, including core divergences over the Exploitation Regulations, differentiated interest demands of participating parties, and the impact of US unilateral practice. Based on the analysis results, some countermeasures are proposed, including promoting the ISA to optimize the review procedure of the Exploitation Regulations, petitioning the Seabed Disputes Chamber of the International Tribunal for the Law of the Sea to render an advisory opinion on the legality of US unilateral authorization of deep-sea mining in the Area, and actively applying for new exploration contract within the Area.

This paper reviews the research progress in numerical simulation of transport and dispersion of plumes generated during deep-sea mining. Based on the formation mechanisms of plumes, the differences between dynamics of collector plumes and midwater plumes are compared in terms of discharge, transport driven by buoyancy and passive advection. By comparing the advantages and disadvantages of widely used near-field and far-field numerical frameworks in terms of applicable scales, computational efficiency, and physical accuracy, the parameterization methods for key physical processes are illustrated. Aiming at the bottleneck of insufficient deep-sea environmental data, the limitations and core challenges in current laboratory flume experiments and in-situ observations for model verification are further analyzed. On this basis, a prospect for the development direction are finally offered, including integration of artificial intelligence and advanced data assimilation techniques with establishment of standardized model evaluation framework.

Three-dimensional non-persistent joints containing random rock bridges were fabricated by adopting 3D printing technology. Direct shear tests were conducted on specimens with joint persistence of five different percentages under three levels of normal stress. On the basis of test data, the laws of variation of shear strength parameters of three-dimensional non-persistent joints with joint persistence were systematically analyzed. The results show that the peak shear strength of joints decreases obviously with the increase of joint persistence. There is a significant difference in the variation of cohesion and internal friction angle with the increase of joint persistence. Cohesion decreases rapidly in a nonlinear manner, while the internal friction angle remains relatively stable. Furthermore, based on the laboratory direct shear test results, rheological elements were introduced to characterize the shear mechanical behavior of specimens, and a shear damage evolution constitutive model was established for non-persistent jointed rock mass. It is found that the calculated results of the model are in good agreement with the experimental data.

For rapid and automatic recognition of blast fragmentation in the Husab Mine in Namibia of Africa, a dynamic recognition model was proposed for blast fragmentation in open-pit mines. By acquiring stereo images through a binocular camera and constructing a depth map, in combination with an improved YOLOv8 instance segmentation model, the classification of gravel and fragmentation analysis were realized. Moreover, transfer learning, ROI extraction, and shadow data augmentation technologies were all adopted to optimize the model, enhancing its recognition accuracy in complex environments. The model training results show that the optimized model can achieve a precision of 0.375, a recall of 0.600, and an accuracy of 0.300. This model exhibits strong robustness in extremely complex scenes of open-pit mines, and is capable of successfully detecting most effective rock blocks from high-noise and high-interference backgrounds. Field measurement data indicate that the model can operate stably in environments with high dust and dynamic lighting, achieving a recognition accuracy of 85% for effective rocks on site, and the error of the fragmentation distribution curve is controlled within 8%. This model provides reliable technical support for the efficient evaluation and intelligent detection of blasting effects in the Husab Mine.

Based on PFC^2D, a numerical model was constructed to systematically analyze the effects of confining pressure and fracture dip angle on the crack propagation, failure modes, and energy evolution of rock mass with cross-fractures. The results show that with the increase of confining pressure, the failure mode transitions from tensile or mixed failure mode under low confining pressure to shear-dominated failure under high confining pressure. As the dip angle increases, the secondary fracture - dominated fracture is shifted to primary fracture - dominated fracture. The confining pressure significantly affects the propagation morphology and quantity of cracks, whereas the dip angle mainly influences the crack initiation location and propagation path. The confining pressure enhances the energy storage capacity of rock samples, promotes strain energy accumulation, and strengthens the overall toughness of the structure. The dip angle mainly affects the energy allocation path. When the dip angle of cross-fractures is 45°, the specimen exhibits an extremely high energy storage capacity and delayed failure behavior, indicating a strong load-bearing capacity but a high rockburst risk. When the dip angle of cross-fractures is 60°, the lower energy storage limit of the specimen leads to sudden burst of energy, demonstrating typical brittle failure characteristics.

Anode sheets of spent lithium-ion batteries were taken for research, and an L₂₅(5⁴) orthogonal test was employed to investigate the effects of ultrasonic temperature, ultrasonic time, ultrasonic frequency and solid-liquid ratio on the separation efficiency of graphite and copper foil in a system with an addition of 0.5% surfactant. A system without surfactant was taken as the control group. The results show that the graphite separation efficiency reaches 95.75% in a system with an addition of 0.5% surfactant, by ultrasonic separation at 90 ℃ for 15 min with a frequency of 100 kHz and solid-liquid ratio of 1∶9. The recovered graphite is basically consistent with those of standard graphite in terms of the XRD diffraction peaks and has a low proportion of disordered structure. The recovered copper foil exhibits favorable mechanical properties, with a tensile strength of 180－190 MPa, and its carrier mobility is 35.68 cm²/(V·s), indicating excellent electrical conductivity.

To optimize the electrochemical performance of lithium manganate (LMO) cathode materials, metal oxides (SnO₂, ZrO₂, La₂O₃, TiO₂) were employed for the coating modification of LMO cathodes. The results show that metal oxide coatings do not change the basic morphology and spinel octahedral structure of LMO cathode materials. The SnO₂-coated cathode material (SnO2@LMO) exhibits better electrochemical performance than those coated with other oxides. SnO₂@LMO delivers an initial discharge specific capacity of 109.87 mAh/g at 1C rate, with a capacity cycle retention rate as high as 98.01%. At high rates, it shows slower capacity fading and superior rate capability. CV and EIS analyses confirm that the SnO₂ coating forms a stable initial interface, enabling SnO₂@LMO to maintain good reversibility after cycling. SnO₂@LMO has both the lowest surface film resistance (R_s) and charge transfer resistance (R_ct), delivers optimal interface stability and charge transfer kinetics.

To achieve high-value utilization of silicon monoxide tailings (SiO-W), SiO-W@G composite anode materials for Li-ion batteries were prepared by granulating the composite of SiO-W and graphite with pitch as a binder, and their electrochemical performances were then compared with those of conventional SiO@G anode materials. The results show that SiO-W@G, with particle size (D₅₀=11.390 μm), is smaller than SiO@G (16.831 μm) and has larger specific surface area (15.66 m²/g vs. 10.80 m²/g), but both have the same tap density (0.99 g/cm³). SiO-W is uniformly composited with graphite, and there is no obvious difference in crystal structure. Electrochemical tests show that SiO-W@G delivers a specific capacity of 443.55 mAh/g and an initial coulombic efficiency of 85.56%, which are close to those of SiO@G (463.65 mAh/g, 86.39%). It is concluded that the granulation of composite can effectively enable the high-value utilization of silicon monoxide tailings, presenting good prospects for industrial application.

Based on investigation of the influence mechanisms of acid and alkaline corrosion for flotation separation of lepidolite and feldspar, efficient separation of lepidolite and feldspar in different particle size fractions was achieved by flotation with surface dissolution and collector interaction. It is found that in flotation process, alkaline corrosion can promote the separation of lepidolite and feldspar more effectively than acid corrosion. Under optimal conditions, lepidolite concentrates in size fraction of 38-74 μm and -38 μm are obtained with recoveries of Li₂O at 92.54% and 83.20%, respectively. The effects of acid and alkaline corrosion on the wettability, morphology, reagent adsorption and electrical potential of the mineral surface were explored by contact angle measurements, high-speed camera observations, SEM, AFM, XPS, infrared spectroscopy and zeta potential analyses. Results show that alkaline corrosion, due to its distinct mechanisms at the surfaces of lepidolite and feldspar, can promote the separation between them; whereas acid corrosion has no selectivity for two minerals. Besides, both acid and alkaline corrosion are independent of particle size of minerals.

High-arsenic white dust was processed by adopting a process consisting of alkaline roasting and water leaching to remove the arsenic therein, and the water leaching residue was then subjected to first-stage sulfuric acid leaching for separation between copper and zinc, followed by second-stage hydrochloric acid leaching for separation between lead and bismuth, so as to comprehensively recover various metals. The effects of alkali-to-ore ratio, roasting temperature and time on arsenic removal by water leaching, along with the suitable process parameters for two stages of acid leaching and stepwise treatment of acid leachate were systematically explored. Firstly, 3 h roasting at 300 ℃ with alkali-to-ore ratio of 0.9 followed by water leaching of calcine achieved arsenic removal rate of 98.88%; and then, the obtained leaching residue with liquid-to-solid ratio of 4 mL/g was leached at 90 ℃for 2 hours with sulfuric acid at an initial concentration of 2.5 mol/L, resulting in the leaching rates of copper and zinc reaching 98.32% and 99.14%, respectively. After that, the sulfuric acid leaching residue at a liquid-to-solid ratio of 4 mL/g was leached at 90 ℃ for 2 hours with hydrochloric acid at concentration of 2.5 mol/L, leading to the bismuth leaching rate up to 98.42%. The previously obtained sulfuric acid leachate was then added by 1.1 times the theoretical amount of sodium sulfide, resulting in copper precipitation rate of 99.87%, and the generated solution was then subjected to evaporation and crystallization, resulting in a zinc recovery of 99.23%. While the previously generated hydrochloric acid leachate was neutralized to pH of 3, leading to a bismuth recovery rate of 99.74%. It is concluded that such combined process can actualize comprehensive recovery and utilization of valuable elements in high-arsenic dust.

 In consideration of high-content of copper and lead therein, copper smelting dust was decided to be leached with a mixed solution of sulfuric acid and sodium chloride. The leachate was then subjected to zinc powder replacement for recovering sponge copper, and the leaching residue was subjected to flotation to achieve effective separation between copper and lead. It is found that with sulfuric acid at an initial concentration of 2.0 mol/L, sodium chloride at concentration of 4.0 mol/L and liquid-solid ratio of 4∶1, 2-h leaching at 90 ℃ results in leaching rates of As and Cu reaching 99.19% and 80.69%, respectively; and the copper replacement rate reaches 92.48% from the copper containing solution with pH of 2 at 50 ℃ by replacing with zinc powder at an amount of 1.8 times of solution. Surface analysis technique reveals that Bi(Ⅲ) remaining on the surface of copper sulfide significantly inhibits the flotation of copper sulfide. Therefore, washing pretreatment shall be added before flotation. After that, a flotation process consisting of one roughing, two cleaning and two scavenging can produce a copper concentrate grading 56.17% Cu at 94.15% recovery, and a lead concentrate with 58.01% Pb grade at 99.14% recovery. It is concluded that this comprehensive treatment by a combined beneficiation and metallurgical route for copper smelter dust can provide a reference in the treatment of other smelting dusts.

A phosphoric acid - ammonium sulfite leaching system was employed to leach valuable metal elements such as nickel, cobalt and manganese from cathode materials of spent ternary lithium-ion batteries. The effects of phosphoric acid concentration, concentration of ammonium sulfite monohydrate, temperature and time of reaction on the total leaching rate of valuable metals were investigated. It is found that with phosphoric acid at the concentration of 0.8 mol/L, ammonium sulfite monohydrate at the concentration of 25 g/L, reaction at 70 ℃ for 90 min can result in the total leaching rate of valuable metals up to 95.2%. After the acid leaching process is kinetically fitted using the shrinking unreacted core model, it is shown that the leaching process is controlled by surface chemical reaction.

With sludge as the main raw material and corn straw as a carbon raiser, porous sludge-based activated carbon (PSAC) was prepared by adopting the ZnCl₂ activation method. The adsorption performance of PSAC for removal of organic dye Rhodamine B (Rh B) was investigated, and the corresponding adsorption mechanism was also explored. Results indicate that PSAC has a rich pore structure, a high specific surface area (703.14 m²/g), and abundant oxygen-containing functional groups, with a point of zero charge (PZC) of 4.2. The adsorption kinetics of Rh B onto PSAC follows the Lagergren’s pseudo-second-order kinetic model, and the adsorption isotherm is better fitted to the Langmuir equation. At 298 K, the saturated adsorption capacity of PSAC for Rh B reaches 196.08 mg/g. The adsorption process is dominated by chemical adsorption, and is spontaneous, endothermic and entropy-driven process. Electrostatic interaction, hydrogen bond interaction, π-π interaction and hydrophobic interaction all play certain roles in the adsorption process, among which electrostatic interaction is the main driving force.

To improve synthesis efficiency and performance of iron phosphate (FePO₄) product, a precursor for cathode materials of lithium-ion batteries, a two-step process consisting of oxidation-precipitation, and conversion was proposed to prepare iron phosphate with ferrous sulfate and ammonium phosphate as raw materials. The effects of key parameters, such as addition amount of hydrogen peroxide (oxidant), feeding rate, and reaction temperature, on the particle size distribution (D₅₀), purity, and Fe/P ratio of the product were investigated. The optimized process conditions were determined as follows: oxidation at a temperature of 40 ℃ for 2 h by adding hydrogen peroxide at an amount of 1.25 times the theoretical dosage and feeding material for 50 min in the oxidation stage; precipitation at a temperature of 40 ℃ by feeding ammonium phosphate for 50~55 min in the precipitation stage; and with phosphoric acid at concentration of 0.6 mol/L and a temperature of 90 ℃ for the conversion stage. As a result, a high-purity iron phosphate with D₅₀ of 3.0 μm, impurity content lower than 0.01%, and Fe/P at a molar ratio of 0.997 can be successfully prepared. SEM and XRD characterization results show that the product consists of regular spherical secondary particles formed with densely stacked primary lamellar crystals, presenting higher degree of crystallinity.

An improved algorithm combining Rapidly-Exploring Random Trees (RRT) and Artificial Potential Field (APF) was proposed for obtaining an overall path planning for deep-sea collector vehicles. Based on the kinematic model of the collector vehicle, the RRT sampling mechanism was optimized by a target-biased strategy, and an adaptive repulsive coefficient was introduced to improve the potential field function, thereby enhancing obstacle avoidance and target reachability.Verification was carried out by simulation under two different working conditions. The results show that in Condition 1 (complex environment), the RRT*-APF algorithm has its searching time shortened by 73.1%, the number of expanded nodes reduced by 50.7%, and the path length shortened from 1542.35 m to 1486.16 m compared to the RRT* algorithm, being more suitable for complex environments. In Condition 2 (simple environment), the RRT-APF algorithm has its searching time shortened by 67.4%, the number of expanded nodes reduced by 52.6%, and the path length shortened from 973.58 m to 910.27 m compared to the traditional RRT algorithm, being more suitable for simple environments.

Spent lithium iron phosphate batteries were taken in a research on lithium extraction by selective leaching process and preparation of high-purity lithium phosphate. It is shown that by adopting a process consisting of leaching with sulfuric acid and hydrogen peroxide, neutralization for impurity removal, and precipitation with sodium phosphate, the lithium leaching rate can reach 98.07% and the iron leaching rate is just 0.28%, after leaching at room temperature with sulfuric acid at a concentration of 0.3 mol/L, hydrogen peroxide at a dosage of 0.50 mL/g, and liquid-solid ratio of 8 mL/g, showing that separation of lithium and iron can be actualized by selective leaching. Then, after the leachate is neutralized with sodium hydroxide for removing impurities, and subjected to precipitation process at a temperature of 90 ℃ for 60 min, with an initial pH of 10.5, sodium phosphate and lithium in a molar ratio of 1∶1, the lithium precipitation rate reaches 96.64%, and a high-purity lithium phosphate product with a lithium content of 16.16% is prepared. It is concluded that by adopting such process, lithium can be efficiently recovered from spent lithium iron phosphate batteries.

In order to understand the development of patented technologies regarding high-nickel ternary cathode materials, a patent analysis is provided here in terms of patent layout, principal applicants for technical innovation and key technologies of structural regulation. It is found that the patents for high-nickel ternary cathode materials are still increasing, and the key technologies of structural regulation with single crystal structure as the hotspot of research are gradually developed in a trend towards composite structural regulation in combination with modification means of doping and coating.

After systematical analysis of the material characteristics of lithium manganese iron phosphate (LMFP) and comprehensive summarization of all preparation technologies based on the current research status of enterprises, the mechanisms of modification strategies, including optimization of manganese-iron ratio, nano-crystallization, morphology and structure regulation, surface coating and ion doping, for enhancing electrochemical performance of LMFP are reviewed. Besides, aiming at the pain points in industrialization, a feasible development path is proposed, which can provide theoretical support and guidance in engineering projects of transition of LMFP from laboratory innovation research to large-scale production, and also facilitate the breakthrough in its commercialization in the fields of energy storage and power batteries.

The distribution of global rare earth elements (REEs) resources and comparative advantages in exploitation and utilization of REEs are analyzed based on literature research and empirical research. It is pointed out that the global rare earth sector is currently confronted with a competition pattern in which global industrial chains are dominated by China and the United States. The competitiveness of rare earth industrial chain lies not only in reserves, but more importantly in the production, processing and utilization of resources, as well as in its role in boosting the industry’s added value in the national industrial system. In terms of resources, in consideration of heavy dependence on external import of medium and heavy REE resources, without advantages such as in light REEs, China should not only strengthen the security assurance of medium and heavy REEs, implement the strategic mineral reserve system, but also make good use of domestic and international medium and heavy REE resources and actively strive for the rights and interests of international mineral resources. In terms of industrial policies, China should continuously implement favorable policies for its domestic rare earth industry, to maintain the global competitive advantages in rare earth industrial chain and industrial clusters, and avoid shifts of its rare earth industry and transfer of related technologies abroad.

This paper presents the evolution path of intelligent technologies, from automated monitoring at early stage to modern AI-based decision support, and focuses on analysis of research results and application cases of key technologies, such as neural networks, the Internet of Things (IoT), digital twins and big data. It also presents discussion of the latest progress in application of a new generation of intelligent technologies represented by machine learning in safety management of non-coal mines. Specifically, technologies including deep neural networks, support vector machines, decision trees and random forests have shown advantages in aspects such as personnel safety management and positioning, monitoring and early warning of mine disasters, safe operation of mine equipment, and safety in mine blasting operation. Finally, the development trends of non-coal mine safety management are proposed, in terms of in-depth application and integration of intelligent technologies, compatibility of old equipment with modern intelligent technologies, and integrated management.

In combination with experiments and multi-step finite element simulation, the residual stress distribution in components manufactured by laser powder bed fusion (LPBF) and the influence of the initial residual stress field on the laser shock peening (LSP)-induced compressive residual stress field. The validity of the simulation results was verified by the residual stress values measured with X-ray diffraction. The results show that the thermal stress of the lower and middle layer materials in the component fabricated by LPBF undergoes a transition from zero stress, compressive stress, tensile stress to compressive stress, while the top layer material shows a transition from zero stress, compressive stress to tensile stress, thus leading to tensile residual stress occurred on the surface layer of LPBF fabricated component, while compressive residual stress in the lower part. The action of initial residual stress field results in the reduced peak value but increased depth of LSP-induced compressive residual stress. The initial residual tensile stress field of LPBF components can exert a suppressive and dragging effect on the reverse plastic deformation caused by surface waves, leading to reduced intensity and changed position of the “residual stress hole”, which can improve the uniformity of LSP-induced residual stress distribution.

To investigate the rheological properties of heat-treatment-free AlSi9MnMg alloy specifically for high-pressure die casting (HPDC) process, influence of temperature and shear rate on the viscosity of molten alloy was studied by using a rotational rheometer based on the Searle principle, and the microstructure of the samples in rheological testing was analyzed. The results indicate that the viscosity of molten alloy decreases as the temperature rises in the test. At a given temperature, the viscosity decreases as the shear rate increases. With the shear rate exceeding 800 s^-1, the viscosity remains unchanged with shear time at the same shear rate. Under the action of shear force, the dendritic grains in the melt undergo fragmentation, agglomeration and spheroidization. Moreover, as the temperature rises in the test, the particle agglomerates become smaller in size.

Based on the Derwent Innovations Index (DII), the technologies for recycling cathode materials in spent lithium-ion batteries were analyzed in terms of patent indicators, including the number of patent applications and patent holders, the number of priority rights in countries/regions, patent citations, patent H-index among others. It is found that the recycling technologies are in rapid development, and the Chinese research organizations have created a patent portfolio plan, including a large number of high-quality patents that can improve competition. Over the past five years, the technologies, including pretreatment processes of discharge and separation, recovery of lithium, nickel, cobalt and manganese, extraction of precious metals by hydrometallurgical and pyrometallurgical processes, as well as recycling equipment, have become hotpots in this field. China has a relatively large number of core patents, mainly involving hydrometallurgical process, direct recycling process, and a combination of pyrometallurgical and hydrometallurgical processes. Finally, some countermeasures and suggestions are proposed for enhancing the competitiveness of China’s industry in recycling cathode materials in spent lithium-ion batteries, which provides references for promoting the healthy development of China’s lithium battery recycling industry.

Based on the causes of historical dam failure accidents in tailings ponds, a safety grade evaluation index system was built for tailings ponds. The correlation between safety evaluation indexes was demonstrated with Pearson correlation analysis method. An in-depth analysis was conducted for the distribution of sample data to confirm that the sample data met the requirements of the Kriging method for data distribution. Then, the weight of each safety evaluation index was calculated with entropy weight method. The two safety evaluation indexes with higher sensitivity were selected as the X-axis and Y-axis of the Kriging geostatistical model. A geostatistical model was established by using the Kriging method and was verified with empirical case data. The results show that the predicted safety grades of 12 groups of tailings pond data with known safety grades in the geostatistical model are completely consistent with the actual safety grades, which verifies the feasibility and high accuracy of this method.

Based on the mining environment and stress characteristics of backfill in the upward horizontal slicing and filling method, the influence of wetting-drying (WD) cycles on the mechanical properties of cemented tailings backfill (CTB) was explored. An ultrasonic test and a mechanical property test were conducted for CTB samples with different cement-tailings (c/t) ratios after different WD cycles to investigate variation in the velocity of longitudinal waves, compressive strength, and failure mode. The results show that after WD cycles, the CTB samples with c/t ratios of 1∶4, 1∶6 and 1∶8 all had a decreased ultrasonic wave velocity, and as the number of WD cycle increases, CTB samples with different c/t ratios had enhanced plastic deformation capacity but decreased strength. It is shown that WD cycle has a small impact on backfill with a higher c/t ratio. And the CTB without WD cycle mainly experiences tension-shear failure, while CTB after WD cycles has multiple axially parallel cracks penetrating vertically, which significantly increase after more WD cycles. It is found that the c/t ratio is a key factor for CTB to resist deterioration caused by WD cycles. In mining operation, the c/t ratio for different filling areas can be reasonably optimized to reduce filling costs.

Homogenization of backfill slurry cannot be automatically evaluated during stirring process. To solve this problem, the Yolo-v7 algorithm was improved by using the CBAM and the SPD-Conv, and the improved Yolo-v7 algorithm was then employed to automatically evaluate the homogenization of backfill slurry. The research results show that the improved Yolo-v7 algorithm demonstrates a significantly improved performance, with the accuracy, recall rate and mean average precision (mAP) all increased by 17.5, 28.8, and 32.4 percentage points respectively. Analysis of slurry parameter sensitivity indicates that slurry concentration is the principal factor affecting evaluation of slurry inhomogeneity, followed by the cement-tailings ratio. Moreover, the homogeneity of backfill slurry with high concentration can be significantly improved by prolonging stirring time.

To enhance the positioning accuracy of seismic source in underground mining and solve the problem of spatiotemporal changes in the wave velocity field caused by excavation disturbance and complex structures, seismic source relocation with real-time inversion of wave velocity field  as a prior was proposed, which combined ray tracing and quasi-Newton iteration algorithm to realize dynamic update of wave velocity field and high-precision positioning of seismic source. The validity of this method was verified by synthetic monitoring and field testing. The synthetic monitoring results showed that compared to the least squares procedure, the real-time inversion resulted in the average positioning accuracy enhanced by 49.8% and the accuracy of wave velocity inversion exceeding 95%. In the field testing, a 180 m×180 m to-be-filled area in mining operation was taken for imaging target. Compared to the least squares procedure, this method brought the average error in positioning reduced by 7.074 m, and the accuracy of wave velocity inversion in each region exceeding 95%. The research indicates that this method not only is suitable for seismic source positioning in microseismic monitoring, but also can be used as a geophysical method for detecting passive imaging of goaf areas.

The polymetallic ore from Shizhuyuan of Hunan Province was taken for research. Based on the characteristics of uneven coarse-fine dissemination of minerals and insufficient deliberation of Mo-Bi sulfide ore for flotation, an enhanced recovery technology by stepwise separation was developed for the low-grade Mo-Bi sulfide ore. The results show that an experiment by adopting such stepwise separation technique produced a bulk flotation concentrate grading 1.31% Mo and 2.83% Bi at corresponding recoveries of 88.43% and 85.99%, presenting 5.34 and 4.80 percentage points up, respectively, compared to on-site conventional bulk flotation process. This creates favorable conditions for the following tungsten flotation from the bulk flotation tailings. It is shown that a closed-circuit tungsten flotation can produce a tungsten concentrate grading 44.64% WO₃ at 84.12% recovery.

In Meishan Iron Mine, the iron concentrate produced on the site has SiO₂ grade more than 6.0%. Aiming at this problem, an experimental study was carried out based on the microscopic identification of different concentrate products by using a new process flow, in which the magnetic field intensity of low-intensity magnetic separation (LIMS) was reduced for roughing, and a process of regrinding and re-separation was added for the scavenging concentrate by high-intensity magnetic separation (HIMS). The effects of those technical transformation on the TFe grade of iron concentrate and the content of impurity SiO₂ therein were explored. The results show that after such technical transformation, the LIMS can produce a concentrate grading 63.57% TFe and 3.37% SiO₂ with corresponding recoveries of 72.79% and 12.94%, with a yield of 52.21%; while the HIMS can produce a concentrate grading 44.79% TFe and 9.07% SiO₂ with corresponding recoveries of 17.20% and 11.67%, with a yield of 17.51%. This new flowchart can produce the concentrate grading 58.85% TFe and 4.80% SiO₂ at corresponding recoveries of 89.98% and 24.61%, with a total yield of 69.72%. It is shown the SiO₂ content in the total concentrate of Meishan Mine can be greatly reduced.

Extraction of rhenium from low-grade molybdenum concentrate by adopting a process of oxidative volatilization followed by ion exchange was explored in experiments. Firstly, a two-stage high-temperature oxidative roasting was adopted to oxidize rhenium into Re₂O₇. Rhenium and molybdenum were effectively separated due to rhenium volatilizing into the flue gas. The volatilization rate of rhenium reached 85.42% after roasting process at 675 ℃. Then, the rhenium-containing flue gas was eluted to get rhenium-containing solution, in which rhenium was selectively extracted with D201×7 ion exchange resin. With the solution pH of 9, liquid/solid ratio of 50 mL/g, a 20 min adsorption at temperature of 35 ℃ brought the adsorption rate of Re up to 97.52% and the adsorption rate of Mo less than 20%. Finally, a product of ammonium rhenate was prepared by stepwise desorption followed by concentration and crystallization. By this process, the total recovery of Re can reach 70.68%.

With nickel laterite ore from Morowali of Indonesia as the raw material, effects of various factors, including reaction time and temperature, stirring speed, acid-to-ore ratio, and slurry concentration, on the leaching rate were systematically investigated. Additionally, the leaching mechanism was explored by using the PHREEQC, a thermodynamic calculation software. The results show that after one hour reaction at 250 ℃, with acid-to-ore ratio of 300 kg/t and slurry concentration of 25%, the leaching rates of Ni and Co can reach 98.40% and 99.90%, respectively, while the leaching rates of Fe and Al are just 3.84% and 40.25%, respectively. The high selectivity of high pressure acid leaching (HPAL) is attributed by the factor that at high temperatures, not only the hydrolysis reaction of Fe and Al can be promoted, but also the pOH can be decreased from 14 to 10,  which thereby inhibits leaching of Fe and Al. As the temperature rises to above 200 ℃, the number of H+ increases, which can ensure a sufficient amount of H+ for leaching of nickel and cobalt metals.

Nickel, Cobalt and Manganese in the cathode materials of spent ternary lithium-ion batteries were recovered by leaching with a combination of citric acid and hydrogen peroxide. The possible reactions during the leaching process were analyzed, and the effects of factors, including citric acid concentration, mass fraction of hydrogen peroxide, leaching temperature, leaching time and liquid-to-solid ratio on the leaching rates of nickel, cobalt and manganese from cathode materials were also investigated. It is found that after 60 min leaching at 80 ℃ with citric acid at a concentration of 1.5 mol/L, hydrogen peroxide at a mass fraction of 8%, and a liquid-to-solid  ratio of 25 mL/g, the leaching rates of nickel, cobalt and manganese are 97.58%, 97.35% and 96.12%, respectively. Then, an antisolvent crystallization method is adopted with ethanol as antisolvent agent to recover metals from the obtained leach liquor, leading to the crystallization rates of nickel, cobalt and manganese at 92.34%, 93.07% and 99.69%, respectively.

A FeCoCrNiMn high-entropy alloy (HEA) coating was prepared on the 201 stainless steel surface by adopting high-speed laser cladding technology, and then the microstructure, phase distribution, microhardness of FeCoCrNiMn coating, as well as its wear properties in dry sliding condition were all investigated. It is found that such laser cladded FeCoCrNiMn HEA coating consists of a single FCC structure, with no obvious cracks observed. It also forms a good metallurgical bond with the substrate. The microhardness of the coating is around (439±2.1)HV, nearly two times that of 201 stainless steel substrate, and the strengthening mechanisms mainly include strengthening by grain refinement and solid solution strengthening. Also, the FeCoCrNiMn coating presents an obviously better wear resistance than 201 stainless steel, with an average  friction factor of 0.246 and a specific wear rate of about 2.59×10^-6 mm³/(N·m).The wear mechanisms for it include adhesive and abrasive wear. It is concluded that such FeCoCrNiMn HEA coating prepared by high-speed laser cladding technology can significantly improve the surface hardness, wear resistance and service life of machine components.