With the increase of mining depth, open stope mining method is facing greater safety hazards and environmental pressure. Filling mining method, as a safe and green mining technology, has been widely used in mining. Taking a large copper mine as the research object, combined with theoretical analysis and numerical simulation methods, the stope structure parameters of upward layered point pillar filling mining method were optimized, and the effects of stope length, point pillar size and point pillar center spacing on stope stability and mine production capacity were systematically analyzed. The results show that when the stope length is 65 m, the point pillar size is 5 m×5 m, and the point pillar center spacing is 15 m, the stability of the mine stope is high and the production efficiency is the best. The optimization scheme of stope structure parameters can not only effectively guarantee the safe mining of the mine, but also improve the utilization rate of resources, which provides a scientific basis for the application of filling mining technology in similar mines.

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 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.

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.

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.

In order to realize the safe and efficient mining of metal mines in the surface protection area, taking the mining of inclined orebodies under slope in Paishanlou Gold Mine as the engineering background, the roof caving characteristics, stability conditions of caving arch and its control and utilization technology in the goaf of inclined orebodies were systematically studied. It was analyzed and concluded that the inclined orebodies in Paishanlou Gold Mine conform to the characteristics of the arch caving model, and the mathematical relationships between the critical caving span and caving height of the inclined orebodies under slope were established. A goaf caving process control scheme with the subarea mining model as the core was proposed, and the subarea open-stope mining with subsequent centralized filling mining technology was developed. The results of on-site practice show that after adopting this mining technology, the mining cost is decreased by 26.8 yuan/t, the production capacity is increased by 20%, the ore loss rate is decreased by 1.5%, the dilution rate is decreased by 3%, and the mined metal quantity is increased by 427.5 kg. This method not only meets the surface protection requirements of Paishanlou Gold Mine, but also achieves the goals of low-cost, safe and efficient mining. The research results can provide technical references for the mining of low-grade orebodies in surface protection areas.

As one of the key processes in the stage open stope with subsequent filling mining method, the quality of the slot raise construction directly affects the effect of the subsequent blasting to form the cutting groove, and ultimately affects the quality of large-scale caving mining. In view of the problems of low intelligence, high safety risk and large occupational injury in the construction of traditional artificial sight distance operation raise boring machine, combined with the mining status and occurrence conditions of porphyry ore body in Shanxi Zijin, the existing construction mode of slot raise was optimized to realize the intelligent construction of slot raise. A dynamic optimization control technology for operation parameters was proposed, which used the mountain climbing method to achieve dynamic parameter optimization, and achieved autonomous and efficient continuous drilling through a remote intelligent control system based on 5G communication technology. The industrial application results show that the raise boring machine with remote intelligent control system can also maintain high-precision hole drilling and hole expansion operations in complex rock formations with fractured zones, with an average pilot hole footage of 1.75 m/hand an average reaming footage of 1.375 m/h, and a deviation rate of only 0.68%. The study can provide a reference for unmanned construction of wellbores in other scenarios.

In order to explore the influences of different cutting parameters on the cutting performance of the oscillating cutting disc, the Discrete Element Method was used to simulate the cutting process of the oscillating cutting disc, and the influences of eccentricity distance, oscillating frequency, feed rate and cutting depth on the cutting performance were studied. The results show that the average load of rock breaking with the oscillating cutting disc is obviously lower than that of the non-oscillating cutting disc. When the feed rate is 60 mm/s, 90 mm/s, 120 mm/s, 150 mm/s and 180 mm/s respectively, compared with the non-oscillating condition, the average load of the cutting disc under the oscillating condition is reduced by 37.37%, 44.19%, 57.47%, 60.32% and 61.25% respectively. Under the same condition, with the increase of eccentricity distance, the average load decreases firstly and then tends to be stable. With the increase of feed rate, the average load decreases gradually, and the maximum load increases gradually and then tends to be stable. When the feed rate is less than or equal to 90 mm/s, the average load increases with the increase of the oscillating frequency. When the feed rate is greater than 90 mm/s, the larger the oscillating frequency, the smaller the average load. When the cutting depth is 40 mm, the average load and the maximum load are the smallest. When the eccentricity distance, oscillating frequency, feed rate and cutting depth of the oscillating cutting disc are 3 mm, 60 Hz, 150 mm/s and 40 mm, the cutting performance is the best. The research results can provide a reference for the determination of the cutting parameters of the oscillating cutting disc.

The contents of silver (Ag), lead (Pb), zinc (Zn), iron (Fe), manganese (Mn) and sulfur (S) in a polymetallic ore in Heilongjiang are 330.52 g/t, 0.57%, 0.29%, 25.77%, 9.05% and 3.38%, respectively. Due to the carbon content is high, mineral dissemination relationship is complex, as well as Ag, Pb and Zn are partially wrapped in Fe-Mn minerals, it is difficult to guarantee the concentrate grade and recovery rate. In order to realize the comprehensive recovery of valuable components in the ore, the process of Ag−Pb−Zn mixed flotation and Fe-Mn magnetic separation was adopted, and the full process closed-circuit test was carried out. The Ag, Pb and Zn grades of the Ag−Pb−Zn mixed concentrate obtained by the test are 3 010.80 g/t, 5.39% and 2.37%, respectively, and the recovery rates are 83.35%, 89.61% and 77.55%, respectively. The Fe grade and recovery rate of the Fe concentrate are 60.97% and 8.01%, respectively, and the total Fe recovery rate is 71.89%. The Mn grade and recovery rate of Mn concentrate are 18.30% and 76.38%, respectively. The tailings yield of the full process is 50.23%, and the Ag, Pb and Zn grades of the tailings are 35.07 g/t, 0.055% and 0.068%, respectively. By using copper sulfate as an activator and butyl xanthate+ammonium dibutyl dithiophosphate as a collectors in Ag−Pb−Zn mixed flotation, the process has realized the comprehensive recovery of Ag, Pb and Zn with high recovery rates, as well as the effective recovery of Fe and Mn, additionally, the backwater can be reused in production.

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.