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.

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.

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.

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.

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.

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.

Abandoned mine not only contains a large number of available resources, but also has many risk factors. In order to scientifically determine the reutilization mode and take into account the risk of many abandoned mines, a risk framework of abandoned mines including six dimensions of technical risk, safety risk, environmental risk, community risk, legal risk and financial risk was constructed, and the risk assessment of reutilization was carried out by LEC risk assessment method. Then, from the perspective of risk management, the method combining improved analytic hierarchy process (IAHP) and TOPSIS was proposed to determine the best reutilization mode of abandoned mines. Finally, taking the closed mine of Muchengjian Coal Mine in Jingxi Mining Area as an example, the proposed method was verified. The results show that the high risk factors of the closed mine are mainly concentrated on safety risk and social risk, and ecotourism is selected as the optimum reutilization mode. This risk management-based method can provide a reference for optimizing the reutilization mode of abandoned mines and effectively reduce the negative effects of mine closure.

China's iron ore resources are increasingly depleted, and they have difficult to select characteristics such as poor, fine and miscellaneous. The traditional anionic collector has large dosage, complex reagent system and poor activity. In order to solve this problem, the surfactant processed by industrial waste amine (YTDB) was used as cationic collector to study the single mineral flotation test and mineral adsorption mechanism of quartz and hematite. The results show that when dodecylamine (DDA) is used as collector, under the conditions of pH=7 and collector dosage of 20 mg/L, the recovery rate of quartz is 78.36%, and the recovery rate of hematite is 12.57%. At this time, the flotation difference is the largest. When YTDB is used as collector, under the condition of pH=7 and collector dosage of 15 mg/L, the recovery rate of quartz is 91.27%, and the recovery rate of hematite is 12.67%. At this time, the flotation difference is the largest. YTDB is obviously better than DDA in flotation index, and saves the dosage of reagent to a certain extent. By testing the infrared spectrum, surface tension and Zeta potential before and after the interaction of the agent and the mineral, it is found that YTDB adsorbed on the surface of quartz.

To reveal the energy consumption patterns of irregular ore particles under impact crushing, impact crushing tests were conducted on six types of iron ore with different properties, and the fractal characteristics of irregular iron ore fragmentation were analyzed, as well as the size effect on average particle size of fragments, fractal dimension, and unit absorption energy. Then, the energy consumption model of irregular single particle crushing was established. The results show that the average particle size of fragments, fractal dimension, unit absorption energy all exhibit a power function relationship with initial isosphere diameter under the same impact conditions. As the isosphere diameter of the particles increases, the average particle size of the fragments gradually increases, and the fractal dimension and unit absorption energy gradually decrease. There is an increasing relationship with power function between unit absorption energy and average particle size of fragments. The relationship between the logarithm of unit absorption energy and fractal dimension shows a linear increase. Through the method of ore crushing tests of irregular single ore particle, relationship models of unit crushing energy consumption of irregular iron ore particles changing with the initial size, average particle size of fragments, and fractal dimension were established, with an average correlation coefficient of 0.789, which effectively describes the energy consumption pattern of ore crushing.