To solve the problems of difficult lithium-sodium separation and low product purity in conventional processes, a pilot study on lithium extraction from spent lithium battery black mass was carried out using the sulfation roasting-alkali leaching process, with the innovative introduction of bipolar membrane electrodialysis technology. The pilot study showed that under optimized process conditions (a volume ratio of black mass to concentrated sulfuric acid of 1∶0.65 and roasting at 540 ℃ for 3.5 h), the lithium leaching rate was stably above 99.38%, and 99.65% of the fluorine in the black mass entered the flue gas, resulting in an extremely low fluorine content in the leachate. The nickel-cobalt-manganese residue obtained after alkali leaching was subjected to two-stage countercurrent acid leaching, and the leaching rates of nickel, cobalt, and manganese all exceeded 99.2%, enabling efficient recovery. To address the high sodium content in the alkali leachate, bipolar membrane electrodialysis was employed to convert the purified lithium sulfate solution into a lithium hydroxide solution with a hydroxide ion concentration of 1.38 mol/L and dilute sulfuric acid with a hydrogen ion concentration of 1.48 mol/L. The lithium hydroxide solution was further purified by nanofiltration and evaporation crystallization to prepare a lithium hydroxide product that met battery-grade quality requirements. The process is simple and efficient, with an overall lithium recovery of approximately 97.9%. Preliminary cost estimation shows that the total processing cost per ton of lithium produced by this process is approximately 94 100 yuan, demonstrating both technical feasibility and economic competitiveness and providing a new approach for the comprehensive resource utilization of spent lithium batteries.

Against the background of intensified price fluctuations and an overall oscillating upward trend in the metal market, traditional decision-making based on a fixed cut-off grade is difficult to adapt to market changes, which is detrimental to the long-term development of mining enterprises. Based on this, the internal logic and economic mechanism between metal price fluctuation and dynamic adjustment of mining cut-off grade were studied. Using the imperialist competitive algorithm (ICA), combined with models such as break-even analysis, multi-metal grade conversion, and stochastic price prediction, a logical framework for the dynamic adjustment of cut-off grade integrating data perception, model decision-making, intelligent execution, and feedback optimization was constructed. Taking a copper polymetallic mine as an example, four scenarios, namely static average price, progressive price increase, stochastic price path, and two-way price-cost linkage, were set up for empirical analysis. The results show that the cut-off grade is significantly negatively correlated with the price level, and dynamic adjustment can effectively prolong the mine production life and increase the net present value; the optimal strategy under stochastic prices is more conservative than that in deterministic scenarios, which can effectively mitigate the downside risk of metal prices; the cost elasticity coefficient has a significant regulating effect on the cut-off grade, and an increase in the cost elasticity coefficient reduces profit volatility while simultaneously weakening profit elasticity during periods of price increases. In the future, mining enterprises should focus on the deep integration of geological, market price and production data, and utilize intelligent technologies to achieve a fundamental transformation from "static design" to "dynamic response", thereby enhancing overall risk resistance capacity and resource utilization efficiency.

To effectively manage and control mine costs and guide enterprises in reducing costs and increasing efficiency, a cost target system was established based on the complete cost. Using Analytic Hierarchy Process (AHP), statistical analysis, graphical methods and case studies, systematic comparison and analysis were conducted on the complete costs of four medium-sized lead-zinc mines both domestically and internationally. The following conclusions are drawn. Mining methods, development systems, and production scales are crucial for controlling complete cost of mines. The compositions of complete cost in descending order of proportion are production cost, taxes and surcharges, administrative expenses, operating expenses, and financial expenses. The complete cost of mines has a scale effect, the larger the production scale, the lower the unit cost. For projects of the same production scale, the complete cost of foreign mines is higher than that of domestic mines. For medium-sized lead-zinc mines, the complete cost of lead is in the range of 10 000 to 17 000 yuan/t, and the complete cost of zinc is in the range of 6 000 to 12 000 yuan/t. The research findings can provide a reference for cost control in the practical production of lead-zinc mines.

The "dual carbon" goals have driven explosive growth in the renewable energy industry, leading to surging demand for critical metals such as copper, nickel, and cobalt. As a strategic supplement to land-based resources, the development of deep-sea minerals has become a critical pathway to ensure supply chain security. Addressing China's high external dependency on critical metals and acute supply chain vulnerabilities, the strategic layout of the entire industry chain for deep-sea mineral resource development was systematically investigated. Building on the vast potential of international seabed resources such as polymetallic nodules, cobalt-rich crusts, polymetallic sulfides and deep-sea rare earths, and leveraging China's "first-mover advantage" of exclusive exploration rights and priority mining rights over five international seabed areas, competitiveness analysis indicates that China has advantages in exploration scale and manned submersible technologies. However, persistent bottlenecks are summarized, including reliance on imported core mining components and insufficient influence in international environmental standard-setting. A framework anchored in "top-level strategic planning, green technology innovation, industrial chain coordination, international rule leadership" was proposed. Key pathways encompass establishing a national collaborative mechanism to advance low-disturbance mining technologies, building a distributed industrial chain spanning "offshore mining-coastal preprocessing-inland refining", and spearheading international standards for sustainable deep-sea mining. Phase-specific milestones are defined: completing full-system sea trials in mining areas by 2030 and achieving an annual production capacity of 20 million tons of dry nodules by 2040. By integrating technological breakthroughs and international rule gaming, this framework provides strategic support for China to build an independent and controllable deep-sea resource supply system.

To ensure efficient resource collection while minimizing environmental impact, enhancing economic feasibility, and promoting the sustainable development of deep-sea hydraulic mining technology, a hybrid evaluation system was constructed for identifying key influencing factors and optimizing solution selection. Firstly, based on grounded theory, a comprehensive evaluation system was constructed from three dimensions of technology, environment and economy, which includes 5 primary indicators (environmental disturbance, collection efficiency, energy consumption characteristics, structural reliability and collection economy) and their corresponding 20 secondary indicators. Next, the Fuzzy-DEMATEL method and the CRITIC method were applied to determine subjective and objective weights, respectively, followed by comprehensive weighting. Finally, the Pythagorean fuzzy multi-attribute decision-making method based on PFHWD-TOPSIS was used to sort the alternatives and achieve scientific optimization. The results show that the constructed hybrid evaluation system can effectively support factor analysis and scheme decision-making, among which environmental disturbance and economic stability are the key constraint factors in the decision-making of deep-sea hydraulic mining schemes. In the four deep-sea hydraulic mining schemes, the wall-attached jet scheme (C₂) has the optimal comprehensive performance, and performs prominently in terms of environmental disturbance, energy consumption characteristics and economy. The research results can provide a theoretical reference for the optimization of deep-sea hydraulic mining schemes and help the sustainable development of the technology.

The hydraulic compensator in marine drilling equipment plays a critical role in regulating the pressure balance between internal and external environments and the machine's oil supply rate. Its working principle involves utilizing seawater pressure to compensate for volumetric changes in hydraulic oil caused by deep-sea pressure and ambient temperature differences, thereby preventing seawater backflow and subsequent equipment corrosion. A mechanical volume analysis on two compensators with different shapes was conducted using Ansys software, and their hydraulic circuits were simulated via AMEsim. Based on the original hydraulic circuit, additional components such as pressure reducing valves, check valves, and overflow valves were incorporated to construct a hydraulic circuit suitable for active operation mode. A comparative analysis of flow velocity before and after the improvements was performed. Furthermore, the influence of different structural parameters on the internal flow field under deep-sea working conditions was investigated. Finally, a new hydraulic compensator was designed accounting for the pressure and temperature conditions of the marine environment. The results demonstrate that the compensator with a multilayer folded structure and an inlet/outlet size of 20 mm delivers optimal performance. Its hydraulic system can supply a larger flow rate within a shorter time and exhibits enhanced adaptive adjustment capability for transient flow variations.

Deep underground metal mines are subjected to the long-term superimposed effects of high in-situ stress and cyclic blast-induced dynamic disturbance, making the surrounding rock prone to stress concentration, cumulative roof settlement, and intensified vibration response, which threaten stope stability and production safety. Existing mining parameter designs mostly rely on engineering experience and struggle to balance stope stability and production efficiency. To address this issue, a dynamic and static coupling optimization method for mining parameters was proposed to synergistically regulate factors such as stope span, pillar width, filling height, and explosive consumption. Dynamic response simulations based on a three-dimensional numerical model and field comparative verification were carried out. The results show that after the coordinated parameter optimization, the peak particle velocity (PPV) at a near-field distance of 10 m decreases from 31.3 cm/s to 14.5 cm/s, and the peak displacement of the bottom structure reduces from -0.64 cm to -0.18 cm. Within 24 hours after blasting, the mid-roof settlement droppes from 9.8 mm to 4.1 mm, and the height of the plastic zone extension in the roof decreases from 8.6 m to 5.1 m. These results demonstrate that the proposed parameter optimization method can effectively mitigate the effects of blast-induced disturbance, improve the stress state of the surrounding rock, and enhance stope structural stability, providing reliable optimization ideas and technical support for safe and efficient mining in deep mines.

The southeast ore body of the Chambishi Copper Mine is a typical deep-level mine in central and southern Africa. As the mining scope continuously expands, the underground ventilation system of the mine faces problems such as long ventilation routes, high ventilation resistance, uneven airflow distribution, and local ventilation difficulties, which severely affect mine production safety and the working environment. Taking the deep-horizon multi-shaft ventilation system of the mine as the research object, and based on systematic investigation and parameter determination, the ventilation districts were rationally partitioned. Furthermore, targeted optimization schemes were formulated from the perspectives of the ventilation network, ventilation engineering, ventilation structures, and ventilation power. In the south mining district, the 696 m level was utilized as the main return airway; coordinated with automatic ventilation doors and short shaft engineering, this configuration ensured the fresh air supply to the ramp. Furthermore, efficient ventilation at the 900 m level was achieved via the 800-680 m dedicated return shaft operating in conjunction with variable-frequency fans. In the north mining district, ventilation structures were added to seal the air leakage at the 980 m level, and a newly excavated intake shaft from the north main ramp to the 1 000 m level resolved the difficulty of fresh air intake in deep levels. A three-dimensional simulation model was established using Ventsim software, and the error between its simulation results and the measured data was less than 10%. After engineering application, the distributed air volume at the 900 m level increases to 102.2 m³/s, the air leakage volume of the south ore body decreases by 57.89%, and the effective airflow rate improves by 19.51%. The air volume in the deep middle level is obviously improved, and the underground environment is significantly improved.

Under the coupled action of high stress and aggressive media in deep mines, the support system is highly prone to structural failure due to stress-electrochemical coupled corrosion, which seriously threatens mine production safety. With the corrosion protection of bolts under a saline-alkali corrosive environment in a deep mine in Shandong taken as the engineering background, field investigation, laboratory tests, and numerical simulation were combined to investigate the variation law of the electrochemical corrosion rate of bolts after adding Cr₂O₃ corrosion inhibitor, and to comparatively analyze the corrosion evolution process of ordinary bolts and bolts with the corrosion inhibitor under the high-stress environment of deep mines. The results show that as the Cr₂O₃ concentration increases, the self-corrosion potential of the bolt rises from -1.062 V to -0.924 V, the corrosion current density decreases from 7.76×10^-5 A/cm² to 1.47×10^-5 A/cm², and the corrosion rate drops from 0.936 mm/a to 0.181 mm/a. The Cr₂O₃ corrosion inhibitor exhibits a significant inhibitory effect on electrochemical corrosion. The grouting body compressive strength test shows that with the increase of Cr₂O₃ concentration, both the 1 d and 7 d compressive strengths of the specimens present a trend of first increasing and then decreasing. The numerical simulation results show that after 1 500 d of corrosion, the ordinary bolt has large potential differences and concentrated current density, whereas the bolt with Cr₂O₃ has a uniform potential distribution. The total electrode corrosion thickness decreases from 68.7 μm to 0.182 μm, a reduction of 99.7%, and the surface concentrations of chloride, iron, and sodium ions on the anti-corrosion bolt are significantly lower than those on the ordinary bolt, indicating that the Cr₂O₃ corrosion inhibitor can achieve long-term inhibition of electrochemical corrosion under high-stress and high-corrosion environments.

To analyze the impact of external flow field pressure variations on the safety clearance during the operation of lifting container in ultra-deep metal mines, and to identify the key factors in the safety clearance design of mixed lifting container in ultra-deep shafts, a closed-loop analysis method integrating "multi-field coupled dynamics-regulatory codes-engineering design" was proposed. This method was utilized to investigate the key indicators of safety clearance for mixed lifting container in ultra-deep shafts under different operating conditions. Relying on the Daping Phosphate Mine mixed shaft project in Guizhou, a standard κ-ε two-equation turbulence model was adopted to perform a numerical simulation on the external flow field pressure variations of the lifting container during operation. The pressure distribution characteristics of the container during steady-state operation and the transient passing process were deeply investigated. Simultaneously, by comprehensively considering the key factors affecting the oscillation of the container, such as the torsional moment of the hoisting wire rope, the Coriolis force, and steady-state aerodynamic forces, the design safety clearance for lifting container in ultra-deep shafts was systematically analyzed and determined. The results indicate that the relative relationship between the operating direction of the container and the main airflow direction in the shaft is the key factor influencing the negative pressure in the passage. Under the counter-flow operating condition, the aerodynamic negative pressure effect is more intense, which makes it the critical operating condition for safety clearance design. Furthermore, the total lateral displacement of the lifting container is 158.8 mm, and the calculated safety clearance is 536.4 mm, which is higher than the safety clearance (528.9 mm) specified in the Safety Regulations for Metal and Nonmetal Mines. The research findings provide a scientific and reliable basis for the safety design of ultra-deep shafts, ensure the stable and safe operation of lifting systems in deep mining, and offer a theoretical reference for the evaluation criteria of safety margins in the safety clearance design of ultra-deep shafts.