In order to solve the problems of significant reduction of rock mass mechanical strength, poor integrity and extremely complex mining technical conditions in the 28-48 line ore body area of the deep −625 m middle section of Lilou Iron Mine due to the influence of weathering zone and fault cutting. The rock mass quality evaluation of four kinds of ore rocks in the upper and lower plates of the ore body area was carried out. It is found that the surrounding rock of the roof is poor, and the outer roadway of the vein should be arranged as much as possible in the stable marble of the lower plate. Based on the rock mass quality evaluation and the roadway failure mechanism analysis, four schemes of no support, bolt+steel arch support, bolt-shotcreting support and bolt-shotcreting+steel arch combined support were selected. FLAC3D software was used to simulate and analyze the stability of surrounding rock of deep −625 m middle roadway under four support schemes. The results show that compared with the no support, the minimum principal stress under the scheme of bolt+steel arch support, bolt-shotcreting support and bolt-shotcreting+steel arch combined support is reduced by 4.05%, 14.02% and 11.59% respectively, and the maximum subsidence of vertical displacement of roof is reduced by 10.33%, 42.46% and 43.35% respectively. The support effect of roadway surrounding rock from weak to strong is no support<bolt+steel arch support<bolt-shotcreting support≈bolt-shotcreting+steel arch combined support, and the support effect of bolt-shotcreting+steel arch combined support scheme is the best. After comprehensive consideration, it is considered that the selection of bolt-shotcreting support scheme can meet the support requirements of most mine weathering zone areas. Only in the extremely broken area, the bolt-shotcreting+steel arch combined support scheme is recommended. The research results can provide a basis for the subsequent operation and production of deep middle roadway and stope mining.

In order to solve the problem of difficult roadway support in deep crushed surrounding rocks, the range of plastic zone was studied. Taking the roadway in the crushed section of a mine as the engineering background, the current situation of roadway damage was investigated, and from the physical properties of the roadway surrounding rock itself, the influences of cohesion and internal friction angle on plastic zone were analyzed by theoretical analysis and numerical simulation system. The results show that the reason for the failure of the roadway under the original support is the poor nature of the surrounding rocks and the neglect of the plastic zone by the support parameters. The cohesion and internal friction angle of surrounding rocks have a significant influences on the range of plastic zone. When the cohesion and internal friction angle are large, the range of plastic zone is small and the surrounding rocks of roadway tend to be stable. When the internal friction angle is 35° and the cohesion is 3 MPa, the change curve of the plastic zone radius turns, which indicates that the combined parameters are the key threshold of the bearing capacity of the surrounding rocks. According to the theoretical analysis and numerical simulation results, the combined support scheme of "anchor (rod), net, spray + full-section anchor cable" was proposed. The field displacement monitoring shows that the maximum deformation of the two sides is about 40 mm, and the maximum deformation of the surrounding rocks of the roof and floor is about 61 mm, which effectively guarantees the stability of the surrounding rocks. The research results provide a theoretical basis for the support technology of deep crushed surrounding rocks in roadway.

With the depletion of shallow resources, deep mining has become the normal state of mineral resources development in China. Taking the approach stope at a buried depth of 1 000 min a mine in Yunnan as the research object, the borehole coring was carried out and the uniaxial compression test and Brazilian splitting test were carried out. Based on the Hoek-Brown criterion and Mohr-Coulomb criterion, the mechanical parameters of surrounding rock mass were obtained, and the numerical simulation study under different approach layout directions was carried out. The influence of principal stress direction on the stability of surrounding rock in approach stope was discussed, and the approach layout scheme was optimized. The test results show that the average uniaxial compressive strength, tensile strength and elastic modulus of the rock in the 1 000 m buried depth range are 96.48 MPa, 3.92 MPa and 33.87 GPa, respectively, and the rock has obvious brittle characteristics. The approach layout direction has a significant influence on the stability of the stope. The simulation results show that with the increase of the angle between the approach direction and the principal stress direction, the displacement and deformation range of the surrounding rock increases. When the approach direction is parallel to the principal stress direction, the displacement deformation of surrounding rock is the smallest and its stability is the best. Based on the numerical simulation results, the mechanical mining industrial test was carried out with the principal stress direction as the excavation direction, and the size of the stope approach was expanded to 4 m×4 m. It is found that the stability of the approach stope is good under the small operation disturbance of mechanical mining.

In view of the technical problems of safe and efficient mining faced by a large iron mine in Anhui province under the complex mining technology conditions, based on the comprehensive investigation and analysis of resource endowment characteristics, mining technology conditions and goaf status, a three-dimensional visualization model of the stope was constructed, and the collaborative mining scheme of upward horizontal layered filling method and sublevel open stoping with subsequent filling method was preliminarily determined. The MIDAS numerical simulation software was used to optimize the stope parameters. The results show that for the ore section at −470 m to −390 m, the upward horizontal layered filling method is suggested to be used, and the optimal stope span is 15 m, with a maximum tensile stress of 0.795 MPa on the roof. For the ore section at −390 m to −330 m, the sublevel open stoping with subsequent filling method is proposed, and the optimal stope span is 18 m, with a maximum tensile stress of 1.763 MPa on the roof. The engineering practice shows that the adoption of collaborative mining scheme has significantly improved the economic benefits of the mine, with a production capacity of 287−354 t/d, a recovery rate of 76.65%−90.82%, and a dilution rate of 3.95%−4.61%.

In order to reasonably determine the thickness of the Quaternary water-resistant roof pillar and the width of water-resistant pillar in the fault of an iron mine in Luanzhou, taking a mine using typical filling mining method in Luanzhou as the engineering background, through theoretical analysis, based on the size optimization of the mine water-resistant pillar, the stability of the optimized size was evaluated by the large-scale finite element numerical calculation model. The results show that after the excavation and filling of the designed ore body, the influence area height under the maximum displacement does not intrude the Quaternary lower weathered rock strata. The maximum and minimum principal stresses are compressive stress, and there is no tensile stress area, which does not exceed the compressive strength of surrounding rocks and is close to the compressive strength of weathered rock strata. Weathered rock does not produce plastic zone failure unit. The sensitive area of the overall displacement of the fault and the pillar is distributed in the range of 0−30 m. The maximum and minimum principal stresses of fault and pillar are compressive stress, and no tensile stress occurs. The compressive stress in the contact area between the fault and the surrounding rock reaches the plastic strength, and the principal stress in the pillar area does not exceed the strength of the pillar. The contact area between the fault and the pillar, the contact area between the fault and the surrounding rock locally produces plastic zone, and the penetrating area is not formed. The ore body above −110 m level is set as the roof pillar to meet the safety requirements of water-resistant mining in weathered rock strata. A 100 m water-resistant pillar is left on the north side of the fault and a 60 m water-resistant pillar is left on the south side to meet the safety requirements of water-resistant mining. The research results can provide a reference for the design and evaluation of water-resistant pillar in the process of underground mining in similar mines.

Aiming at the problem of the safe thickness of the isolation layer in an iron mine from open-pit to underground mining, the technical means combining theoretical calculation and numerical simulation was adopted to analyze the influence characteristics of the underground ore body mining process on the surface settlement and rock movement under the condition of different thickness isolation layers. The results show that the safe thickness of the isolation layer of the iron ore is from 11.25 m to 24.41 m based on the theoretical calculation method. The numerical simulation results show that when the thickness of the isolation layer is 15 m, 20 m and 25 m, the surface settlement displacement of the surface structures, the open-pit slopes and the dump sites are all small, which can meet the stability evaluation standard of the rock mass. Considering the safety of mining and avoiding the loss of mineral resources, the safety thickness of the isolation layer is recommended as 20 m. After the implementation of the plan, it is expected that the comprehensive production capacity of the mine will increase by 20%, the safety accident rate will decrease by 53%, it has advantages in terms of safety reliability, technical feasibility and economic rationality. The study can provides an important reference for similar mines to conduct open-pit to underground mining.

In order to reduce the cost of filling mining, slag powder-cement was used as a composite cementitious material, and the response surface method was used to obtain the optimal ratio of filling materials that could meet the strength requirements of a mine filling body. Firstly, through the strength test of filling body with different cement-sand ratios (slag powder-cement : tailings) and the slump test with different slurry mass concentrations, the ranges of slag powder dosage and slurry mass concentration were preliminarily determined. Then, based on RSM-BBD module, the strength regression model of slag-based cemented filling body at different ages was established, and the influences of slag powder dosage, cement-sand ratio and slurry mass concentration on the strength of cemented filling body were analyzed. The results show that the interactions of slag powder dosage and slurry mass concentration, slag powder dosage and cement-sand ratio, cement-sand ratio and slurry mass concentration have significant effects on the 3 d strength, 7 d strength and 28 d strength of the filling body, respectively. Finally, combined with the engineering requirements, the best ratio of filling materials was recommended. Mine practice shows that the use of slag-based cementitious materials instead of cement for mine filling can reduce the cost of filling cementitious materials by 12%−13%.

In order to study the strength formation mechanism of sulphoaluminate-based grouting backfill with different additions of fly ash under acidic environments, the early strength development and microstructure evolution of sulphoaluminate-based grouting backfills were characterized by uniaxial compression tests, XRD phase analysis, thermal analysis (TG) and MIP mercury porosimeter pore tests. The results show that when the addition of fly ash in the grouting backfill is 10%, the strength at 1 d of hydration is 11.05 MPa, and the strength at 7 d of hydration reaches 26.73 MPa. When the addition of fly ash is increased to 50%, the strength at 1 d of hydration is only 4.06 MPa, while the strength at 7 d of hydration is 10.05 MPa, which indicates that the strength loss caused by high addition of fly ash is obvious. Under the influence of acidic environment, the strength of grouting backfill of each ratio decreases. The strength loss of sample adding 10% fly ash is 17.60%, 19.36% and 21.42% respectively, and the strength of sample adding 50% fly ash is decreased by 21.01%, 28.89% and 39.45% respectively. High fly ash addition and acidic environment can increase the threshold pore size and porosity of the backfill, resulting in a decrease in the early strength of the backfill. In the actual grouting reinforcement, the negative effects of acidic environment and external additives on the setting rate of the cementitious system and the early strength of the backfill should be fully considered to ensure the grouting reinforcement effect of the coal roadway.

The blasting quality of fan-shaped blasthole has a significant effect on the application effect of non-pillar sublevel caving method. In view of the problems such as serious damage of eyebrow line, uneven blasting fragmentation and large loss and dilution when the non-pillar sublevel caving method was used in the west second mining area of Longshou Mine under the condition of ore-rock breaking, ANSYS / LS-DYNA was used to optimize the charge structure parameters of the fan-shaped blasthole. The results show that the blasting effect of fan-shaped blasthole can be effectively improved using W-type staggered charge at orifice, hole bottom initiation and millisecond blasting in row. The optimized blasthole charge structure parameters are applied to the field production practice. The ore recovery rate is increased by about 36%, the ore dilution rate is reduced by about 31%, the bulk rate is reduced by 52%, and the damage of the eyebrow line is also significantly reduced.

Aiming at the problems of poor durability and water stability of traditional gravel transportation roads in open-pit mines, the transportation roads were modified using solid waste around the mine. The ratio of blasting waste rock and surrounding soil in the cement stabilized layer was determined by laboratory tests. The unconfined compressive strength, water stability and durability of the cement stabilized layer with different the dosages of curing agent were discussed. The results show that the unconfined compressive strength of the unmodified material is lower than 0.2 MPa, and when the ratio of blasting waste rock and surrounding soil is 4:6, the strength of blasting waste rock can be fully utilized and the pavement can be well formed. The curing agent can significantly improve the strength of the material. When the dosage of curing agent is 8%, the unconfined compressive strength exceeds 2.5 MPa, the water stability coefficient is 137.68%, and the saturated compressive strength of the sample exceeds the initial unconfined compressive strength. In the dry-wet cycle test, the compressive strength of the sample increases significantly and then decreases slightly with the increase of the number of cycles. When the dosage of curing agent is more than 6%, the durability is significantly improved. The deflection value test and comprehensive cost analysis were carried out using the combination of stone-soil ratio of 4:6 and dosage of 8%. The results show that the deflection value of the modified pavement is 9.07 (0.01 mm), the pavement quality was significantly improved, and the comprehensive cost is 47.5 yuan/m², which is significantly lower than that of the original gravel pavement.

In response to the problems that the traditional prediction model is easy to fall into local optimal solution, the weight and threshold of BP neural network were optimized by seagull optimization algorithm (SOA), and the SOA-BP prediction model was constructed. Based on the time series settlement values of multiple high coherence points, the model can accurately predict the surface settlement in a large-scale in the mining area. The SBAS-InSAR technology was used to process 59 SAR images of the research area, and the time series settlement values of 6 997 high coherence points in the area were extracted. Based on the monitoring data, the SOA-BP prediction model was used to predict the surface settlement in the research area, and the prediction accuracy was calculated. The results show that compared with BP model, the maximum root mean square error of SOA-BP model is reduced by 82.77%, and the maximum mean absolute error is reduced by 81.13%. With the passage of time, the proportion of samples with residual distribution within ±5 mm of SOA-BP model is increased from 79.59% to 91.91%, and the maximum residual extreme value is decreased from 16.722 4 mm to 9.421 9 mm. The prediction accuracy of SOA-BP model is high, and it can accurately predict the law of surface settlement.

Aiming at the limitations of traditional methods for determining the rock movement angle under the geological conditions of steeply inclined multiple ore veins, a comprehensive analysis method based on the critical granular column theory and numerical simulation was proposed. Taking the Shagou stope of Faende mining area in Henan Province as the research object, through engineering analogy, theoretical analysis and numerical simulation, the influence law of the mining of steeply inclined multiple ore veins on the rock movement angle was deeply studied. The nonlinear relationships between rock movement angle and vein distance, vein quantity, as well as dip angle of ore body were revealed, and corresponding empirical formulas were established. The results show that the range of the rock movement angle in the mining area is from 69° to 78°, and the proportion of the height of the critical granular column ranges from 15.8% to 20.7%. By combining the height of the critical granular column with the dynamic correction model of the rock movement angle, the delineation scheme of the safety pillar was optimized, increasing the resource utilization rate to 82.3%. Based on the results of theoretical calculation and engineering practice, a dynamic correction model of the rock movement angle under the coupled action of multiple ore veins was proposed, breaking through the applicable boundary of the traditional analog method for single ore veins, and providing a strong basis for the safe mining of similar complex steeply inclined multiple ore veins.

In response to the problems of imbalanced sample data and low prediction accuracy in the construction of rock burst intensity grade prediction models, a rock burst intensity grade prediction model (BO-CNN-LSTM-Multi-head Attention) based on convolutional neural networks (CNN) and long short-term memory networks (LSTM) was proposed by integrating Bayesian parameter optimization algorithm (BO) and Multi-head attention mechanism (Multi-head Attention) under the rock burst sample data balancing strategy. 224 sets of rock burst cases were collected from both domestic and international sources, and Box-Cox transformation and support vector machine synthesis for few class oversampling technique (SVM SMOTE) were used to normalize and balance the rock burst sample data. The processed dataset was input into the CNN-LSTM prediction model for training and prediction, and the model was gradually optimized by Bayesian parameter optimization algorithm and multi-head attention mechanism. The prediction results indicate that Box-Cox transformation and SVM SMOTE sampling can effectively reduce the impact of outliers and data imbalance on the model, and enhance the separability of the dataset. The accuracy of the BO-CNN-LSTM-Multi-head Attention rock burst intensity grade prediction model is 95%. This model can effectively improve the prediction accuracy of rock burst intensity in the case of imbalanced sample data, and has a high feasibility and practicality.

The layered characteristics of rock mass in the main vein roadway of a lead-zinc mine in Yunnan with a buried depth of 1 500 m are obvious, the ground pressure is severe, and the stability control of surrounding rock mass is difficult. Based on the engineering geological investigation and test materials, the numerical model of engineering geological body was established using 3DEC numerical simulation software. The deformation and failure characteristics of surrounding rocks of roadway were compared under two working conditions of unsupported and designed support after excavation of roadway with different dip angles of the rock strata. Then, the actual deformation monitoring of roadway was carried out. It is found that the horizontal and vertical displacements of the roadway are significantly affected by the dip angle of the rock stratum. As the dip angle of the rock stratum increases, the horizontal displacement gradually increases and the vertical displacement gradually decreases. The deformation of surrounding rocks decreases obviously after roadway support, and the shape of plastic zone is similar to that of unsupported roadway, but the range is smaller. After applying the support, the roadway roof displacement monitoring was carried out. It is found that with the passage of time, the roof displacement gradually increases and tends to be stable after about 70 days, and the displacement of the roof gradually decreases with the increase of the dip angle of the rock stratum. Therefore, the support system used in mines can effectively reduce the deformation of roadway in deep layered rock mass, especially the horizontal deformation of the roadway vault and the vertical deformation of the right side, which is conducive to maintaining the long-term stability of the roadway.

When there is a cavity in the surrounding rock of the roadway, it will have a serious adverse effect on the stability of the roadway. In order to solve the problem of significant deformation and failure caused by the influence of filling unconnected roof cavity under the floor in the last sublevel stoping route of caving method stope in Longshou Mine of Jinchuan, the failure mechanism and support mode of the mining approach were studied by means of field investigation, numerical simulation and field test. The results show that the unconnected roof cavity is deformed under the action of stress concentration after the excavation of the approach, which leads to the synergistic deformation of the surrounding rock of the approach, and the existence of the cavity provides the development space for the deformation of the surrounding rock, which is the main reason for the serious deformation and failure of the approach. According to the position of the cavity and its control effect on the stability of the mining approach, an asymmetric support scheme was proposed. In this scheme, the unconnected roof cavity was regarded as the weak point of the whole support system to impose support, so as to reduce the adverse effect of the cavity on the stability of the approach. The field application results show that compared with the original support scheme, the asymmetric support scheme significantly improves the support effect, reduces the deformation of the two sides of the approach by more than 80%, and reduces the support cost by about 11.7%, which improves the stability of the stope and ensures the safe production of the stope.

In order to avoid the phenomenon that the good rock is over-supported and the poor rock is under-supported, based on the XGBoost algorithm combined with the roadway safety factor, an intelligent evaluation and optimization design system of on-demand support in Longqiao Iron Mine was developed. 7 on-demand anchor mesh support indexes and 5 on-demand plain spray support indexes affecting the stability of roadway in Longqiao Iron Mine were used as the main input values. 60 sets of practical roadway data were selected as examples to carry out the on-demand optimization support design and effectiveness evaluation. The results show that at the level of −370.0 m, the surrounding rock grade is better, the safety factor is larger, and the support measures are not needed. At the level of −382.5 m and −395.0 m, the surrounding rock grade is slightly worse, the safety factor is slightly lower, and the plain spray support form is required. At the level of −407.5 m and −420.0 m, the surrounding rock grade is above the third grade, and the surrounding rock properties are poor, so it is necessary to adopt the form of anchor mesh support. The intelligent evaluation and optimization design system of on-demand support provides real-time rock mass quality evaluation and support scheme optimization for Longqiao Iron Mine, which has effectively improved the safety of roadway and significantly saved the support cost.

Rainfall is a primary factor inducing landslides on slopes, especially the slope repaired after in-situ leaching of ionic rare earth mine is more susceptible to rainfall infiltration. Taking the slope of an ionic rare earth mine in South China as the research background, the influences of rainfall, duration and rainfall type on slope stability was systematically analyzed based on the monitoring data of soil moisture and finite element simulation. The results show that the proportion of deep infiltration (deeper than 60 cm) events (accounting for 19.79%) of single-peak and multi-peak rainfall is significantly higher than that of concentrated (accounting for 1.04%) and uniform (accounting for 5.21%). The numerical simulation shows that the slope stability under the condition of low rainfall (10−20 mm/d) is concentrated>uniform>single peak>multi peak. The stability of single peak type is the worst when the rainfall is high (50 mm/d). With the increase of rainfall duration, the slope stability coefficient under concentrated and uniform rainfall conditions shows a trend of slow decline and then rapid decline, and the slope stability coefficient under single-peak and multi-peak rainfall conditions shows a trend of rapid decline and then slow decline, which is closely related to the sudden change of matrix suction caused by peak rainfall intensity. The research can provide a theoretical basis for the prevention and control of rainfall-induced landslides in ionic rare earth mines.

In order to study the influence of prefabricated fracture length on the tensile properties and fracture deformation characteristics of different rock materials, notched semi-circular bend (NSCB) specimens of three typical brittle rocks, including granite, medium sandstone and limestone, were selected for loading tests. The deformation of the specimen during failure was monitored by digital image correlation (DIC). The results show that the fracture toughness of rock specimens is positively correlated with mechanical parameters such as compressive strength, tensile strength and elastic modulus, and the bearing capacity of NSCB specimen is negatively correlated with the length of existing cracks. When the fracture length exceeds a certain value(a≥3 mm), the bearing capacity of NSCB specimen has a negative exponential relationship with the fracture length. The deformation characteristics of NSCB specimens are significantly affected by the crystal structure and micro-crack distribution of rock. The higher the degree of cementation of rock minerals, the denser the rock crystal structure, the less developed the micro-cracks, the higher the fracture initiation stress, and the smaller the deformation degree before failure, and vice versa. The research results can provide a basis for further understanding the fracture propagation mechanism of rock materials and predicting its expansion range.

In the process of mineral exploitation, rock mass often bears different degrees of dynamic load. A series of dynamic impact and uniaxial compression tests were conducted to analyze the characteristic stress and acoustic emission characteristic parameters of sandstone after impact. The influence of dynamic disturbance damage on the mechanical behavior and acoustic emission response characteristics of sandstone specimens was studied. The results show that with the increase of impact velocity, the longitudinal wave velocity of sandstone specimens after impact test decreases gradually, while the internal damage variable increases gradually. With the increase of impact velocity, the ratio of crack closure stress to peak stress of sandstone specimens increases gradually, while the ratio of crack initiation stress to peak stress and the ratio of damage stress to peak stress decrease gradually. In the process of rock deformation and failure, acoustic emission activity shows significant stage evolution characteristics, and its activity intensity and frequency characteristics will change significantly with the damage evolution inside the rock. The research results can provide theoretical basis for the stability evaluation and support design of roadway surrounding rock under blasting disturbance.

In order to realize the accurate prediction of mine dust concentration, based on the field monitoring data of a mining working face in a coal mine in Shaanxi Province, the random forest (RF) model was used to construct a multi-factor dust concentration prediction model by taking temperature, humidity, wind speed and dust concentration at the current moment as input vectors. Four intelligent optimization algorithms (Newton-Raphson-based optimizer (NRBO), sparrow search algorithm, grey wolf optimizer and whale optimization algorithm) were proposed to optimize the parameters of random forest (number of trees and number of leaf nodes). The model was evaluated by determination coefficient(R²), root mean square error (RMSE) and mean absolute error (MAE). The results show that the optimal model for dust concentration prediction is NRBO-RF model. Compared with RF model, the R², RMSE and MAE of NRBO-RF model are increased by 0.030 3, 0.572 8 and 0.074 9, respectively, and its fitting ability and prediction accuracy are the highest. The research results can provide a reference for intelligent prediction and prevention and control of mine dust.

To explore the impact mechanism of ecological restoration project on the migration and release of antimony in groundwater in TinMine of Hunan, hydrochemical comparisons and hydrogeochemical simulations were conducted on groundwater samples collected from TinMine in 2016 and 2023. The changes in groundwater hydrochemical characteristics and antimony content before and after ecological restoration were analyzed. The results show that ecological restoration has varying degrees of impact on the antimony content in three different limestone fracture aquifers in the mining area, among which the Shetianqiao formation and TinMine formation are significantly affected by mining activities and external pollution, and the antimony mass concentration generally increases. The level of groundwater in the lower carboniferous formation aquifer is low and there is an aquitard, resulting in a decrease in antimony content. The source of Sb before and after ecological restoration has strong differentiation, and its migration and transformation are significantly affected by large-scale soil and green covering projects. The ecological restoration project has changed the redox environment and accelerated the oxidation of Sb (Ⅲ) in groundwater. The main form of antimony in groundwater is . The research results can provide scientific basis for the prevention and control of heavy metal pollution in ecological restoration projects in mining areas.

In view of the scarcity of topsoil and the shortage of solid waste resources in the northwest mining area, the soil reconstruction technology based on coal gangue in the mining area was studied. The coal gangue (CG), rock and soil stripping (RS) and topsoil (TS) from a coal mine in Tongchuan, Shaanxi Province were selected as raw materials, and the reconstructed soil was mixed in different proportions to carry out the pot experiment of alfalfa. The results show that the physical and chemical properties of the reconstructed soil under different proportions were different. In general, the reconstructed soil increases the nutrient and moisture content of the soil, which is more conducive to the growth and development of alfalfa. Compared with TS, the pH of the reconstructed soil decreases, the organic matter, total nitrogen and available potassium increase, while the available phosphorus decreases. The treatment of CG 40% and RS 15% is the most favorable for the growth of alfalfa. The highest plant height of alfalfa is 54.60 cm, the longest root length is 23.20 cm, and the maximum fresh weight and dry weight are 14.814 g and 4.849 g, respectively. The above results indicate that the reconstructed soil formed by CG is feasible for the phytoremediation of mines in Northwest China, and provides a new choice for the comprehensive utilization of CG.

In order to strengthen the safety management of non-coal underground mines and clarify the characteristics of hidden dangers in non-coal underground mines, the total number of hidden dangers, types of hidden dangers and characteristics of major hidden dangers in 52 non-coal underground mines were statistically analyzed. The results show that the number of general hidden dangers is about 11.8 times that of major hidden dangers, and the number of on-site management hidden dangers is about 1.1 times that of basic management hidden dangers. The number of major hidden dangers of on-site management is about 1.3 times that of basic management. Major hidden dangers are mainly concentrated in Article 23, Article 20, Article 4 and Article 31, which are 28, 21, 19 and 13 items respectively. In view of the characteristics of major hidden dangers, it is proposed that mining enterprises should strengthen the construction of organizations, fully invest in safety funds and improve and improve safety facilities, as well as safety management departments should extend supervision tentacles, innovate supervision modes and strengthen supervision compatibility. The research results will provide reference for the safety management of non-coal underground mines.

Aiming at the problem of difficult diagnosis of mining truck drive system, an intelligent fault diagnosis model was proposed by combining wavelet packet and ensemble empirical mode decomposition (EEMD) method, which was integrated into intelligent operation and maintenance system and applied to mine truck. Firstly, the wavelet packet was used to denoise the vibration signals of bearings and gears in the drive system. Then the EEMD algorithm was used to decompose the signal into several intrinsic mode function (IMF) components, and the feature vector was extracted from the IMF components containing the main state information. Secondly, the support vector machine (SVM) was used to classify the fault modes. The penalty parameter C and kernel function parameter h of SVM were optimized by particle swarm optimization (PSO), genetic algorithm (GA) and multi-population genetic algorithm (MPGA). Four fault diagnosis models of SVM, PSO-SVM, GA-SVM and MPGA-SVM were constructed respectively. It is concluded that MPGA-SVM is the optimal fault diagnosis model, and the diagnostic accuracy of bearing fault and gear fault is the highest, which is 98.75% and 6.67% respectively. Finally, aiming at the RE1060 drive system of XDE320 electric-driven mining dump truck, an intelligent operation and maintenance system including four modules of signal acquisition and storage, time-frequency analysis, fault feature extraction and intelligent fault diagnosis was developed by MATLAB and LabVIEW. The research shows that the intelligent operation and maintenance system can realize on-line monitoring and diagnosis of existing faults, which is of great significance to improve the safe and efficient operation of mining trucks.

In order to study the safety design and intelligent design of multi-stage pipeline oil vertical transportation system in underground mines, the numerical relationship model between maximum thrust and single rod length in the installation process and the dynamic vibration analysis model of vertical oil pipeline with different section sizes and different lengths were established. The numerical model of water hammer effect and pressure relief transportation of oil transportation system was built, and the dynamic response characteristics of water hammer pressure under different oil flow and different valve closing time conditions were studied and analyzed. The results are as follows. Firstly, when the length of a single pipe is at a certain value, the installation thrust increases sharply with the increase of pipe diameter. Secondly, the pipe sand filling method can reduce the vibration of the main pipe caused by bubble excitation. Thirdly, reducing the oil flow or increasing the valve closing time can effectively reduce the water hammer pressure. At the same time, the intelligent design schemes of intelligent refueling technology, intelligent dispatching technology, intelligent monitoring technology, intelligent fire protection and fire automatic extinguishing technology are proposed, which plays an important role in the in-depth study of the safety intelligent design of pipeline oil vertical transportation system.

In order to explore the influence mechanism of structural parameters of vertical spiral stirred mill on grinding performance, the coupling method of discrete element method (DEM) and computational fluid dynamics (CFD) was used to systematically analyze the effects of mill bottom gap, side gap and helical lift angle on grinding performance. Firstly, the numerical model of the vertical spiral stirred mill was constructed, and the dynamic characteristics of the medium in the grinding process were revealed by simulation. Secondly, the grinding test was carried out based on the test bench, and the accuracy of the simulation model was verified by the driving torque of the spiral agitator. The results show that the maximum error is only 3.85%. Finally, through multi-parameter simulation and orthogonal test, the influence degree of each structural parameter on grinding performance was quantified, and a comprehensive evaluation method based on energy utilization rate, torque, average normal force and tangential force was proposed. The results show that the side gap of the mill has the most significant effect on the grinding performance, followed by the bottom gap and the helical lift angle. The optimal parameter combination is the ratio of the bottom gap to the medium sphere diameter A=4.0, the ratio of the side gap to the sphere diameter B=3.0 and the helical lift angle C=0.61. The research can provide a reference for the structural optimization and performance improvement of vertical spiral stirred mill.

In order to explore the effect mechanism of magnetization treatment on the reverse flotation behavior of hematite in dodecylamine-cassava starch system, water, starch, dodecylamine and pulp were magnetized respectively, and the mechanism of magnetization treatment in reverse flotation of hematite was analyzed by detecting the changes of reagent adsorption capacity, contact angle and Zeta potential under different magnetization methods. The results show that under the conditions of pH=9, starch dosage of 800 g/t, dodecylamine concentration of 20 mg/L and flotation machine speed of 2 100 r/min, the flotation recovery rate of hematite can be increased by 2.78, 4.16 and 3.84 percentage points respectively by magnetized water, magnetized starch and magnetized pulp. Magnetized water, magnetized starch and magnetized pulp can increase the capacity of starch adsorbed on the surface of hematite particles and reduce the contact angle of the solution on its surface. At the same time, magnetized water and magnetized starch also make the Zeta potential of hematite particles shift positively, while magnetized dodecylamine makes the Zeta potential shift negatively. Magnetized water and magnetized starch promote the adsorption of starch on the surface of hematite. Magnetized dodecylamine inhibits the adsorption of starch on the surface of hematite. Magnetized pulp promotes the hydrolysis of hematite surface, so that more starch can be adsorbed on the surface of hematite particles, thus improving the recovery rate of hematite.

A new inhibitor PN has been developed for copper sulfur flotation separation to address issues such as pipeline blockage and environmental pollution caused by the use of lime inhibitors. The selective inhibition performance and adsorption mechanism of PN inhibitor in flotation process were studied through systematic tests. The results indicate that PN inhibitor has a good selective inhibitory effect on pyrite, but has almost no effect on chalcopyrite. The results of the artificial mixed ore separation test show that under low alkali conditions (pH=8), the optimal separation effect of pyrite and chalcopyrite can be achieved when the dosage of PN inhibitor is 5 mg/L, and a copper concentrate with a copper grade of 31.3% and a copper recovery rate of 92.9% can be obtained. The contact angle measurement results indicate that PN inhibitor can selectively enhance the hydrophilic properties of pyrite surface. The analysis of the microstructure characteristics and elemental content changes of pyrite before and after PN treatment further confirms that PN inhibitor undergo physical adsorption on the surface of pyrite, which can achieve selective inhibition of pyrite. The research results prove that PN inhibitors has the potential to replace lime in copper sulfur separation.

A certain magnetite ore in Zimbabwe has a TFe grade of 42.01%, with fine particle size and high content of silicate minerals. To achieve effective dissociation of iron minerals and gangue, as well as improve the recovery rate of iron resources, a combined process of weak magnetic-strong magnetic-reverse flotation was adopted for experimental research. Through the grinding fineness test, it was determined that the coarse grinding fineness was −0.074 mm, accounting for 81%. The weak magnetic concentrate was further ground to −0.037 mm, accounting for 90%, and the strong magnetic concentrate was further ground to −0.037 mm, accounting for 85%. The magnetic field strength test results show that magnetic field strengths of four weak magnetic operations are 0.33 T, 0.20 T, 0.15 T and 0.10 T, respectively. When the magnetic field strength of the strong magnetic operation is 1.0 T, weak magnetic concentrate with a Fe grade of 62.26% and a Fe recovery rate of 12.25% and strong magnetic concentrate with a Fe grade of 51.32% and a Fe recovery rate of 64.76% could be obtained. For the strong magnetic concentrate, the optimized reagent system through reverse flotation condition experiments is determined with slurry pH of 11.0, corn starch dosage of 500 g/t, CaO dosage of 800 g/t, and self-developed collector CK-T1 dosage of 300 g/t. The closed-circuit test adopts the process of one coarse, two fine, and two scans, and the final Fe grade of the iron concentrate is increased to 65.95%, with a Fe recovery rate of 81.45%. Research has shown that the combination of fine grinding and weak magnetic-strong magnetic-reverse flotation processes can significantly improve the sorting efficiency of fine-grained magnetite, providing a technical reference for the efficient recovery of similar refractory ores.

In response to the problems of low grade, fine embedded particle size, and difficulty in separating copper and molybdenum in a certain porphyry copper-molybdenum ore in Xinjiang, a principle process flow of “copper-molybdenum mixed flotation, concentrate regrinding and copper-molybdenum separation” was determined. Through single-factor condition tests, the key technical parameters of each flotation operation were optimized, and on this basis, a whole process closed-circuit test was conducted. The results show that the stage grinding and stage separation can effectively control the degree of dissociation of the target minerals and avoid the overgrinding of the easily muddled gangue minerals. The copper concentrate with Cu grade of 23.58%, Mo content of 0.046% and Cu recovery of 82.97%, as well as the molybdenum concentrate with Mo grade of 34.21%, Cu content of 0.96% and Mo recovery of 66.38% are obtained by the whole process closed-circuit test of copper-molybdenum mixed flotation with one roughing, three cleaning and two scavenging and copper-molybdenum separation with one roughing, seven cleaning and one scavenging. Effective separation and recovery of copper and molybdenum have been realized. The research results can provide a technical basis for the efficient development and comprehensive utilization of the copper-molybdenum mineral resources.

In order to improve the separation accuracy of magnetite ore with particle size of 20−50 mm and adapt to the change of ore quality, a magnetite ore classification method based on fuzzy wavelet neural network (IGWO-FWNN) was proposed. Firstly, feature extraction was performed on the data set, and the adaptability of the model was enhanced by fuzzification and quantization. Then, the improved grey wolf algorithm was used to optimize the initial parameters of the model, which ensured the efficiency of model training. In the training process, the fuzzy rule parameters were continuously updated by the gradient descent algorithm to optimize the performance of the network model. Experiment results show that compared with the GWO-FWNN model, the accuracy of the optimized network model reaches 0.966 7, the F₁ value reaches 0.951 2, and the convergence speed of the model is also improved by 24%. The results have verified the effectiveness of the proposed method on the iden tification and classification of magnetite ore, which provides a new thought for the development of magnetic separation technology.

In view of the problems of large dosage of reagents and high cost in the traditional lime-free sodium sulfide flotation process of copper-cobalt sulfide ore and sulfur-oxygen mixed copper ore, a study on the optimization and adjustment of the reagent system was carried out at a processing plant in the Democratic Republic of the Congo. The pH and flotation environment of pulp were adjusted by adding lime to reduce the dosage of Na₂S. As the amount of lime increases, the dosage of Na₂S continues to decrease, and the impact on copper-cobalt recovery is relatively small. However, when the amount of lime increases to a certain value and then increases again, the decrease in Na₂S dosage is relatively small, while the cobalt recovery rate of copper-cobalt sulfide ore decreases more significantly, and the copper recovery rates of both ores also show a downward trend. For copper-cobalt sulfide ores, when the lime dosage is 500−700 g/t, the Na₂S unit consumption is reduced from 637.71 g/t without lime to 312.48 g/t, and the recovery rates of copper and cobalt are 93.38% and 91.82%, respectively. For sulfur-oxygen mixed copper ore, when the lime dosage is less than 350 g/t, the Na₂S unit consumption is decreased from 732.57 g/t without lime to 517.35 g/t, and the copper recovery rate is 86.01%. After the optimization of the reagent system, the cost of flotation reagent for copper-cobalt sulfide ore is reduced from the original USD 1.77 to USD 1.58 per ton, with a decrease of 10.73%. The cost of flotation reagents for sulfur-oxygen mixed copper ore is reduced from the original USD 2.12 to USD 1.74 per ton, with a decrease of 17.92%, all of which have good economic effects.

Under the influence of multiple factors such as slowdown of global economic growth, intensification of geopolitical conflicts and acceleration of energy transformation, the mineral resources market presents complex and changeable characteristics. In order to better grasp the current situation and development trend of mineral resources development and utilization in China, a combination of quantitative and qualitative research methods was adopted, and statistical and comparative analysis methods were comprehensively used to conduct in-depth analysis of domestic and foreign mineral resource market data. By sorting out key indicators such as mineral product output, price, investment, import and export, the operational situation of China's mineral resources market was revealed. By comparing the development and utilization of mineral resources between China and major economies in the world, the status and characteristics of China in the global mineral resources market were clarified. The development and utilization of mineral resources in China was comprehensively analyzed, and the internal and external factors facing its development were grasped. The results show that in 2024, the trend of the global mining market is obviously divided, the price of energy minerals falls, the price of most non-ferrous metals rises, and the price of precious metals such as gold continues to rise sharply. China's mining investment has increased, geological exploration investment and mining fixed asset investment have maintained a high growth trend, and the development of mineral resources has shifted significantly to the west. The proportion of relevant indicators in the western region has continued to rise, the diversified mining development pattern dominated by state-owned holding enterprises has become more reasonable, and the production efficiency of mining enterprises has been continuously improved. The development and utilization of mineral resources generally shows a trend of “quantity increase and price decrease”. The national raw ore production continues to grow, but the price of mineral products generally declines, resulting in a year-on-year decrease in the total output value of the mining industry, the sales income of mineral products and the total annual interest and tax of enterprises. Looking forward to 2025, the slowdown of global economic growth and the increase of supply will lead to the weakening of the international bulk mineral market and the differentiation of the price trend of different mineral products. The global geological exploration investment has fallen back, but the domestic geological exploration investment is expected to continue to increase. The production of China's mining industry is expected to remain stable, but the economic benefits and profits of enterprises have declined. Energy transformation will greatly promote the growth of demand for clean energy technology minerals, and the market value of key minerals is expected to reach $770 billion in 2040. To this end, China needs to give full play to the advantages of a unified domestic market and economic internal circulation, and strengthen the real economy. Scientific and technological innovation should be relied on to promote the transformation and upgrading of energy and mineral resources industry. International cooperation should be strengthened to ensure the effective supply of overseas mineral resources. And sustainable development and utilization of mineral resources should be promoted, so as to provide a solid guarantee for high-quality economic development.