In order to monitor the chlorophyll content of plants quickly and non-destructively, two different microbial reclamation treatments (inoculation group and control group) were set up, and six herbaceous plants (Astragalus adsurgens, Medicago sativa, Leymus chinensis, Agropyron cristatum, Elymus sibiricus, Bromus inermis) were selected according to four kinds of mixed sowing ratios (1∶1, 1∶2, 1∶3, 2∶1). The chlorophyll content and spectral reflectance of Astragalus adsurgens in the test area were measured respectively. Using the original spectrum, the logarithm of the reciprocal of the original spectrum, and the first-order differential, combined with three modeling methods of BP neural network regression, support vector machine (SVM) regression, and random forest (RF) regression, models were established for plant spectral characteristic curves under different treatments. The results show that the inoculation treatment increases the chlorophyll content, and the chlorophyll content is also different under different mixed sowing ratios. Compared with the original spectral curve, the modeling accuracy of the reciprocal logarithm and first order differential of original spectral is improved to varying degrees, and the modeling accuracy of FDR is the best. Under the condition of microbial reclamation, the RF regression model has the highest accuracy. Under the conditions of different planting ratios, the model established by BP neural network regression in the 1∶2 and 1∶3 regions of legumes has high accuracy, while the spectral samples in the 1∶1 and 2∶1 regions are more suitable for using RF regression method.

In view of the characteristics that the soft powder ore rock in the deep mining underground roadway of Jinshandian Mine can not take out the complete sample on site, the direct test of compressive strength of loose soft rock mass by rebound instrument was explored. Taking the powder ore and skarn fracture zone of −425 m and −455 m horizontal tunneling roadway in the east-west mining area of Jinshandian Mine as the research object, the rebound value was tested by rebound instrument. Based on the strength formula of concrete compressive strength detected by rebound instrument in national standards and industry standards, according to the engineering geological characteristics of Jinshandian Mine, the empirical formula was optimized, and the correlation sample of rebound value and compressive strength was constructed. Using mathematical statistics method, two modified empirical formulas for strength measurement of soft powder ore rock in Jinshandian Mine were obtained by regression. The results show that the average rebound value of −425 m horizontal powder ore rock in the east-west mining area is 19.35, and the average compressive strength is 6.58 MPa. The average rebound value of −455 m horizontal soft rock fracture zone in the west mining area is 21.92, and the average compressive strength is 14.994 MPa. The results are basically consistent with the results of the inversion of the soft powder rock roadway based on the convergence value of the roadway in Jinshandian Mine. The research results provide a feasible solution for the situation that was impossible to take samples on site for indoor rock compressive stength test under poor engineering geological conditions in underground engineering.

Fiber-reinforced wet-mix shotcrete has excellent properties such as deformation resistance and crack resistance. To evaluate the support performance of fiber-reinforced wet-mix shotcrete, a series of tests were conducted, including uniaxial compressive tests, notched beam flexural toughness tests, and disk flexural tests. The test results indicate that, although the addition of fibers slightly reduces the compressive strength of wet-mix shotcrete, the flexural strength and energy absorption capacity have been significantly enhanced. The roadway support test results shows that the compressive strength of the steel fiber wet-mix shotcrete can reach 25 MPa, the thickness of the spray layer is maintained at 100−150 mm, with a minimal rebound and notable support effectiveness.

Dynamic disasters such as rockburst caused by mining disturbance seriously restrict the development and utilization of deep mineral resources. It is of great significance to explore the propagation process of internal cracks in rocks to reveal the rock failure mechanism and disaster warning. Based on this, the spatial-temporal response characteristics of acoustic emission of granite under uniaxial loading were monitored. The single linkage clustering (SLC) method was used to construct the SLC structure of acoustic emission events. By introducing the spatial correlation length of acoustic emission events, the spatial correlation degree between acoustic emission events at different time scales was analyzed. The results show that the three-dimensional localization and energy properties of acoustic emission events can characterize the propagation and damage evolution process of microcracks in granite specimens. As the stress increases, the link length in the SLC structure gradually decreases, and the correlation within the crack cluster increases. The spatial correlation length has experienced three stages of high-level fluctuations, stable fluctuations and sudden increase. When it is close to the fracture of granite, the spatial correlation length increases sharply due to the redistribution and transmission of stress in the sample, which can be used as the early warning point of granite instability. The SLC method provides an effective method for studying the evolution process of rock crack propagation, which can provide a reference for the early warning and prevention of dynamic disasters such as rock burst.

With the widespread application of lithium-ion batteries in underground mines, the safety issue of mining batteries has become increasingly prominent. The thermal runaway characteristics of large capacity lithium iron phosphate batteries for mining were studied by overcharging tests of 200 Ah LiFePO₄/C battery cell and battery module under different overcharging rates (0.5 C, 1 C, 1.5 C). The results show that the thermal runaway behaviors of the lithium iron phosphate batteries are divided into three stages: shell expansion, slow flue gas injection, and violent flue gas injection with subsequent natural cooling. As overcharging rate increases, the overcharged capacity required in each stage gradually decreases. The temperature after thermal runaway of the battery can reach up to more than 400 ℃, and the maximum temperature in the battery module test is significantly higher than that in the battery cell test. High temperature will pose a severe challenge to the safety of underground mines, and corresponding cooling and protective measures need to be taken. The thermal runaway effect of overcharged battery in the battery module does not cause thermal runaway reactions of adjacent batteries. The critical conditions for the thermal runaway chain reaction of mining batteries still need further study.

With the deepening of environmental protection concepts and the continuous advancement of battery technology, the development of new energy vehicles has entered an explosive growth period, and it has also triggered a wave of disposal of retired batteries. In order to cope with the challenge of efficient and green recycling of waste lithium iron phosphate (LFP) batteries, the main literatures on the recycling of lithium iron phosphate batteries at home and abroad in recent years were comprehensively reviewed, and the latest developments of pretreatment, regeneration and repair, pyrometallurgical and wet recycling technologies were systematically introduced. By analyzing and comparing the main characteristics and shortcomings of various recovery technologies, the advantages of wet selective leaching in current recovery practice were pointed out, and the necessity of its development in the future comprehensive recovery of all components and multi-process coordination was emphasized.

To optimize the mechanical strength performance of mine waste rock-tailings cemented backfill, the Box-Behnken design within the response surface methodology (RSM) was used to conduct a three-factor-three-level test. The synergistic effects of waste rock particle size (0 to −5 mm, +5 mm to −10 mm, +10 mm to −15 mm), mass concentration (84%, 86%, 88%), and sand-to-binder ratio (53%, 60%, 67%) on the uniaxial compressive strength of backfill at different curing ages (7 and 28 days) were systematically explored. At the same time, the traditional orthogonal test was introduced to compare the prediction accuracy and efficiency with the RSM. The RSM results reveal that particle size of waste rock predominantly governs the early-stage strength of the backfill, while mass concentration significantly influences the later-stage strength. The synergistic interaction between particle size and mass concentration is the most pronounced, jointly regulating the skeleton stability and interfacial bonding properties of the backfill. After experimental verification, the accuracy (R²) of the backfill strength prediction model obtained based on RSM is 0.994 9 (7 d) and 0.983 7 (28 d), respectively. The corresponding optimal filling material proportion condition are waste rock particle size of +5 mm to −10 mm, mass concentration of 85.5%, and sand-to-binder ratio of 58.6%. The results of the orthogonal experiment indicate that the particle size of waste rock plays a dominant role in the backfill strength in the early and later stages. Research has shown that RSM can effectively analyze the nonlinear coupling relationship of multiple factors, and the prediction accuracy is significantly improved compared to traditional orthogonal experimental methods.

The measurement error of the filling batching system is the key factor affecting the quality of the filling body. In order to reveal the effect of the fluctuation in mass fraction and pumping agent dosage caused by the measurement error on the working performance of the filling slurry, based on the cement hydration mechanism and the action principle of the pumping agent, the response surface and variance analysis methods were used to carry out mechanical properties, flow properties and rheological properties tests, and industrial test verification was carried out to determine the optimal mass fraction and pumping agent dosage. The results are concluded as follows. Firstly, when the mass fraction and pumping agent dosage fluctuated within ±1%, the main effect significantly affected the 28 day strength, viscosity, slump, expansion and average viscosity coefficient, and the interaction effect significantly affected the 28 day strength, viscosity and average viscosity coefficient. Secondly, fluctuations in mass fraction and pumping agent dosage can cause changes in the proportion of free water in the filling slurry, thereby affecting the working performance of the filling slurry. Finality, it is suggested that the fluctuation range of the mass fraction of the mine should be kept between 78% and 79%, and the fluctuation range of the pumping agent dosage should be kept between 1% and 2%. The research results can provide a theoretical basis for the construction of filling batching systems and the accuracy calibration of batching equipment.

In view of the limitations of existing technologies in the field of hydrometallurgy regarding green environmental protection, the application value and development potential of the glycine leaching system as a new type of green hydrometallurgical leaching technology were explored. By analyzing the unique physicochemical properties of glycine and its application advantages in the hydrometallurgy industry, the development history of the glycine hydrometallurgical leaching technology was reviewed, the research status and commercial dynamics of this technology in treating different types of mineral resources were sorted out, and the main existing problems of the technology were systematically summarized. The research results show that the glycine green hydrometallurgical leaching technology can expand the existing technologies in the metallurgical industry, and has the potential to replace the traditional cyanide gold extraction technology, especially in the field of rare and precious metals. Meanwhile, from aspects such as applicable fields, leaching efficiency of target metals, universality for secondary resources, and the mechanism of synergistic leaching systems, the development direction of the technology is clarified. The glycine green hydrometallurgical leaching technology has significant application value in the field of green hydrometallurgy, and can provide references for metal resource utilization, recovery of rare and precious resources, and secondary resource processing.

The coarse aggregate backfill has high rigidity, poor toughness, and local energy storage accumulation, which is easy to cause safety problems. The addition of fiber can improve the toughness and ductility of the backfill and enhance its mechanical properties. Using coarse aggregate, waste rock, rod sand and river sand from Longshou Mine of Jinchuan as raw materials, the effect of fiber blending process on uniaxial compressive strength of backfill was studied. Design-Expert software was used to analyze the influences of various factors (slurry mass concentration, fiber volume rate, and cement content) on the early mechanical properties of backfill and optimize the parameters. The nonlinear regression models between the early uniaxial compressive strength value and various factors were established to reveal the interaction effects between different factors, and the cost of filling slurry material after adding fiber was calculated. The results show that the addition of fiber can significantly improve the compressive strength of the backfill. Compared with the blank group without fiber (3.03 MPa), the strength of the backfill in scheme Ⅱ (wet mixing of filling materials firstly, and then adding fibers in three stages) is 4.35 MPa, with an increase of 43.56%, which is the optimal scheme. The significant influencing factors of early mechanical properties of fiber reinforced backfill are ordered as slurry mass concentration > cement content > fiber volume rate. The interaction effect between slurry mass concentration and cement content is the most significant, which verifies the reliability of the regression model. After adding fibers, the cost of filling slurry material only increases by 0.67%−15.6%. On the premise of meeting the strength requirements of the backfill, the content of coarse aggregate and cement can be appropriately reduced, which can also reduce the cost.