The disturbance such as deep engineering blasting and excavation is prone to induce rock burst. To study the conditions and characteristics of rock burst induced by cyclic disturbance in deep tunnels under different stress conditions, granite specimens with semi-circular arches penetrating the tunnel were used to conduct true triaxial disturbance rockburst tests. The occurrence conditions, characteristics of rock burst in deep engineering, the evolution process of acoustic emission, and the energy evolution characteristics inside the rock were analyzed. The test results are concluded as follows. Firstly, when the disturbance amplitude exceeds 10 MPa, rock burst will occur in the specimen. For every additional 10 MPa of disturbance amplitude, the time from the start of disturbance loading to the occurrence of rock burst in the specimen is reduced by about 30%. The greater the disturbance amplitude, the more severe the damage to the specimen, and the more shear cracks on the rock surface. Secondly, cyclic disturbance significantly promotes the generation and extension of shear cracks. The disturbance not only increases the number of shear cracks but also accelerates the speed of crack propagation. Thirdly, the accumulated elastic strain energy inside the specimen increases with the increase of disturbance amplitude. When the specimen fails, these accumulated energies are rapidly released, leading to more severe failure of the specimen.

The Shaiqihe Phosphate Mine in Yichang, Hubei has entered deep mining, and rock burst disasters are frequent in the excavation working face. Water injection was used to soften the surrounding rocks in the working face to prevent rock burst, and reasonable water injection parameters affected the prevention and control effectiveness of rock burst. The uniaxial compression tests of phosphorite under different water-containing states were carried out. The relationship between water content and rock burst tendency of phosphorite was analyzed based on the rock strength brittleness coefficient. Numerical simulation was used to explore the distribution characteristics of water content in the surrounding rocks of the working face during water injection, and the optimal water injection parameters for the excavation working face of the Shaiqihe Phosphate Mine were determined. The results show that when the water content of the phosphorite reaches 0.424%, the phosphate rock layer is in a moderate rock burst tendency, and the change in strength brittleness coefficient with water content is no longer significant after water injection. When the water injection time is 1 hour and the drilling depth is 10 meters, the growth rate of effective wetting distance is the highest, and the water injection effect is the best. The research results have certain guiding significance for improving the water injection process parameters of phosphate rock and reducing the risk of phosphate rock burst.

Reasonable nozzle structural parameters are crucial for the desorption performance of walking tracks of deep-sea mining vehicles. Taking the adherent substrate between the walking tracks of the mining vehicles as the research background, numerical simulation of the walking track desorption effect was carried out using Ansys software for the structural parameters and layout design of the nozzles, and the optimal parameters of the nozzles for the desorption of the walking tracks were determined from the calculations and analysis of the velocity of jet impacting on the track teeth and the distribution of the dynamic pressure on the surface of the track plate. The results show that the cavitation effect of the nozzle is very weak when the submerged depth is 5 000 meters, and the design of the nozzle for deep-sea submerged jets may not consider the cavitation effect. Increasing the diameter of the nozzle can significantly increase the length of the core area of the jet. For diameter straight nozzles which are 10 mm, 20 mm and 30 mm, the jet velocity starts to decay rapidly around at 0.09 m, 0.2 m and 0.31 m respectively. The optimal desorption effect of the walking track is achieved when 7 straight nozzles with a diameter of 30 mm and a 90° spray angle are used. Numerical simulation results can provide a strong theoretical basis for the study of the desorption performance of seafloor traveling tracks of deep-sea mining vehicles.

Aiming at the problems of difficult mining, low mechanization and limited resource utilization of gently inclined thin ore body in a fluorite mine in Guizhou, combined with the occurrence characteristics and mining technical conditions of the ore body, it was recommended to adopt mechanized upward horizontal layered filling mining method. According to the structural parameters of the stope and the extraction technology, the stability of the stope was analyzed using Mathews stability graph method and numerical simulation software. The results show that the stope span, the exposed area of the hanging wall and the roof are less than the theoretical limit. The roof settlement of stope is between 0.96 − 4.32 mm. The maximum floor heave value of the bottom is 3.5 mm. The maximum compressive stress of the mining room is 9.8 MPa. The tensile stress value is far less than the tensile strength of the filling body 0.44 MPa. The plastic zone does not form penetration and the stope is always stable. After field application, the production capacity of the ore block is 150 t/d, the mining-cut ratio is 12.96 m/kt, the loss rate is 10%, and the dilution rate is 8%, which has achieved good economic benefits.

Aiming at the problems of low production capacity, many mining and cutting projects, high cost, poor working environment, many hidden dangers and high risks in the 2 230 m and 2 170 m middle stopes of Pakrut Gold Mine, based on the rock physical and mechanical properties tests and RMR (rock mass geomechanics classification index), the reasonable stope size was obtained by using Mathews stability diagram method. The stope was changed from the original four 12 m low segments to two 21 m high segments. Taking the mining width as the variable, the stability of the stope under the condition of mining one block separated by three blocks was simulated by FLAC3D, and the optimal stope width was determined to be 11−12 m. The industrial test indicated that after optimizing the structural parameters of stope, the stope production capacity was increased by 20%, the loss rate was reduced by 4.67 percentage points, the dilution rate was reduced by 3.25 percentage points, and the kiloton mining ratio was reduced by 36%, and the stope did not collapse, the desired results had be reached. The research shows that based on the rock physical and mechanical properties tests and RMR rock classification, the method of optimizing stope structure parameters by Mathews stability diagram method and FLAC3D numerical simulation and then verifying the parameters by industrial test has a high application value.

In order to improve the utilization rate of point pillar resources in Xianglushan tungsten mine and control the impact of point pillar mining of shallow buried depth, analysis was conducted on the technical conditions for mining the underground residual pillars. Combined with the current common point pillar mining schemes and selection principles to determine two filling and mining schemes suitable for point pillar in Xianglushan tungsten mine of shallow buried depth. Furthermore, numerical simulations were conducted to calculate and analyze the displacement and plastic failure of each scheme at burial depths of 50 m, 100 m, 150 m, and 200 m. At the same time, to reduce the impact of underground blasting vibration on ancient buildings, the relationship between the maximum allowable single section dosage and the distance for underground blasting was calculated. Finally, industrial tests were conducted in the 610 mining area of Xianglushan Tungsten Mine to verify the mining scheme. The research results show that during the implementation of the mining scheme, there is no significant change in ground pressure and displacement monitoring data, and the stability of the goaf is good. The total amount of extracted ore is about 21 000 t, and the residual ore recovery rate within the height of the goaf in the mining area reaches about 38.33%, achieving good economic benefits.

The stope structure parameters of the mine are important factors to ensuring safe and efficient mining. With the background of the No. I ore body of a copper mine in Yunnan Province, four different point pillar sizes were proposed by engineering analogy method. And the displacement and stress of the stope under different point pillar sizes were analyzed by FLAC3D numerical simulation software. The results show that when the excavation is to the fourth layer, the 4 m×6 m and 5 m×5 m point pillar size schemes can withstand the maximum tensile stress beyond the mining site, and the two schemes can be excluded. The tensile stress of mining sites with 5 m×6 m and 6 m×6 m point pillar size schemes has not reached the limit state, but the optimization effect of rectangular point pillar is obviously better than that of square point pillar. Finally, the reasonable size of point pillar has been determined to be 5 m×6 m, which can provide a reference for mine stope test.

In order to explore the optimization of the mining effect of the gently inclined medium-thick orebody and the migration law of ore and waste rock, the gently inclined medium-thick orebody in the middle section of－400 m to－360 m in Caogou Mine was taken as the research background. Physical tests of three different mining sequences were designed to study the influence of mining sequence on the mining effect of orebody. The discrete element software PFC2D was used to study the migration law of ore and waste rock. The results are concluded as follows. Firstly, the ore recovery rate of the mining sequence III is 45.56%, the ore dilution rate is 19.29%, and the difference of recovery and dilution is 26.27%. Compared with the difference of recovery and dilution of the mining sequence I and the mining sequence II, the difference of recovery and dilution of stoping sequence III increased by 1.95 percentage points and 4.01 percentage points respectively. Therefore, the mining sequence III is the optimal mining scheme, that is, the upper caving orebodies of the No.3 and No.2 outlets being alternately mined for three cycles, then the upper caving orebody of the No.1 outlet will be continuously mined; and after the No.1 outlet being mined, the upper caving orebody of the No.2 and No.3 outlets will be alternately mined. Secondly, in the early stage of ore drawing, the displacement vector of ore and waste rock particles above and around the ore drawing port tends to the center of the ore drawing port axis. In the later stage of ore drawing, the displacement vector of ore and waste rock particles above the ore drawing port gradually tilts to the left. Thirdly, before the start of ore drawing and after the end of ore drawing, the contact force chain of ore and waste rock particles is in equilibrium. In the process of ore drawing, the contact force chain of ore and waste rock particles is in an unbalanced state.

The shape of the ore draw-out body is the basis for determining the stope structural parameters of the non-pillar sublevel caving method, and the ore moisture content and the fine particle content are the two important factors affecting the shape of the ore drawing body. Taking the ore under the overlying rock of an iron ore caving stope as the research object, the similar physical experiment and numerical simulation of ore drawing were carried out under the conditions of ore moisture content of 0−8% and fine particle content of 5%−25%. The values of λ₁and λ₂ of the vertical and horizontal axis ratios were used as indicators to evaluate the shape of the ore drawing body, and the shape characteristics of the ore drawing body under the synergistic effect of moisture content and fine particle content were explored. The results show that the values of λ₁ and λ₂ of drawing body of physical ore drawing test are consistent with those of the numerical simulation. With the decrease of moisture content or fine particle content, the values of λ₁ and λ₂ of the drawing body decrease, and the shape of the drawing body is closer to the shape of pour water drop. On the contrary, the closer the shape of the drawing body is to the ellipsoid shape. When the moisture content of the ore is 0 and the fine particle content is 5%, the shape of the drawing body is the best, and the ore drawing effect is the best. When the moisture content of the ore is 8% and the fine particle content is 15%−25%, the ore drawing is blocked and the ore drawing effect is the worst. When the moisture content is 2% and the fine particle content changes in the range of 5%−25%, or the fine particle content is 10% and the moisture content changes in the range of 0−8%, the change of the values of λ₁ and λ₂ of the drawing body is the smallest, and the shape of the drawing body is the least affected by the synergistic effect of moisture content and fine particles. The research results provide a reference for the optimization of stope structure parameters of the non-pillar sublevel caving method.

A lead-zinc mine adopts the sublevel rock-cutting stage room method to mine a sharply inclined medium-thickness ore body. On the basis of ensuring the stope stability, in order to further improve the benefits of mining, the Mathews stability diagram method was used to analyze the stope stability of the No.I ore body of the mine as the research object. By calculating the stability coefficient and hydraulic radius, the limit span of roof surrounding rock and side wall surrounding rock is 55.79 m and 44 m respectively, which shows that the current span of the mine of 50 m is reasonable. Combined with the calculation results, 9 schemes with different stage heights and roof thicknesses were formulated, and the numerical simulation studies on the stope stability under 9 schemes were carried out using FLAC3D to compare and analyze the maximum principal stresses, the minimum principal stresses, roof displacements, and plastic zone maps of the different schemes. Through the analysis of the simulation results, it is found that the optimization of the roof thickness from 8 m to 7 m and the stage height of 40 m are reasonable parameter combination, which can not only ensure the stope stability, but also improve the profitability of mining.

In order to reduce the cost of mine filling, the experimental study of filling binder was carried out using low-activity slag and other auxiliary materials around Timok copper-gold mine. The optimal formulation obtained by orthogonal experiment is slag : lime : caustic soda : desulfurization gypsum=81.5:10:1:7.5. The hydration mechanism of slag-based binder was studied by XRD and SEM analysis methods. Combined with the local material price and processing cost, the production cost of slag-based filling binder was calculated, and its application range was recommended. The results show that the 28 d cementation effect of the slag-based binder is slightly lower than that of the local cement, and its cost can be reduced by 30% compared with the local cement. In Timok copper-gold mine, the application of slag-based binder to the filling of sublevel open stoping with subsequent filling method can reduce the cementing cost by 13%. The annual saving of filling cost is 1.281 million euros, which has certain application value.

In the process of pipeline transportation of tailings slurry from beneficiation plant to filling preparation station, changing the feed parameters will change the spatial distribution of tailings solid particles in the pipeline, which will affect the safety and stability of slurry pipeline transportation. Taking the sulfide ore tailings transported by pipeline from a tin ore beneficiation plant in Yunnan to filling preparation station as the research object, the rheological parameters of the tailings slurry were obtained by rheological test. The ANSYS-FLUENT numerical simulation software was used to simulate and analyze the pipeline transportation of the tailings slurry. The relationship between the relative height of the bottom bed layer and the feed parameters was fitted, and a three-dimensional relationship model between the relative height of the bottom bed layer and the feed speed and volume concentration was established. The results show that the three-dimensional relationship model between the relative height of the bottom bed layer and the feed speed and volume concentration has a good fitting effect. Most of the coarse particles with a size of +120 mesh have sedimentation in the bottom bed layer. Some of the fine particles with 120−200 mesh have sedimentation at the bottom bed layer of the pipeline when the feed speed is 1 m/s, and distributed in the carrier layer when the feed speed is above 2 m/s. More fine particles of －200 mesh are distributed in the carrier layer. There is water in the boundary layer of the top wall of the pipeline and the slurry formed by some very fine particles and water, which together form the boundary layer. The change of volume concentration of tailings slurry along the radial direction can be divided into four regions. There is a gradient decreasing effect from the bottom wall of the pipeline to the carrier-bottom bed interface, it gradually increases to stability from the carrier-bottom bed interface to the stable radial volume concentration of the slurry. It remains stable after reaching the maximum value in the stable constant region of radial volume concentration, the radial volume concentration gradually decreases from the stable point to the top wall of the pipe.

In order to improve the filling efficiency and realize the continuous and stable desanding of the tailings storage thickener, combined with the actual situation of the mine and the test results of static and dynamic flocculation and sedimentation, the particle swarm optimization (PSO) algorithm was used to optimize the support vector machine (SVM) regression analysis method. The prediction model of desanding stability was established, and the prediction model was updated by the hybrid point addition method. The optimal parameters were determined by the optimization algorithm to realize the prediction of desanding stability of the tailings storage thickener. Taking Dongxinzhuang Iron Mine as an example, the optimal scheme of thickener structure parameters and desanding parameters based on PSO-SVM was completed and verified by industrial tests. The results show that the mud layer height and the combined effect of mud layer height, sand concentration and thickening time have the greatest influence on the stability of desanding. The PSO-SVM prediction model has a good accuracy in predicting the desanding stability, with a relative error of 1.36%. The research results can provide a theoretical basis for the selection of thickener shape parameters and desanding parameters, and can effectively improve the desanding stability of thickener.

Red mud as mine filling materials can solve the storage problems, but metal ions and acid ions in mine water will corrode the filling body and affect their stability. Indoor simulation tests were conducted based on the backgrounds of Bulianta Mine and Cuncaota Mine, and the impact of mine water on the compressive strength of the filling material was characterized by the erosion resistance coefficient to determine the optimal ratio of raw materials. The variation law of compressive strength of the filling body in mine water was analyzed, and the degree of erosion of the filling body by mine water was evaluated through indicators such as compressive strength loss rate and apparent failure path. Combining with testing methods such as scanning electron microscopy and energy dpectrum analysis, the micro mechanism of the action of mine water on the filling body was revealed. The results show that when the mass concentration of the slurry is 56% and the ratio of red mud, calcined kaolin, and cement is 5:4:1, the compressive strength of the specimen at 28 d is 1.98 MPa, and the initial flowability of the slurry is 260 mm, which meets the performance requirements of the filling body and achieves large-scale consumption of red mud. After soaking in sulfuric acid and sodium hydroxide solutions for 28 d, the compressive strength of the specimens decreases by 7.3% and 2.8% respectively compared to pure water immersion conditions, with corresponding corrosion resistance coefficients of 0.92 and 0.97, respectively. The microscopic test results show that the filling body has been in an acid-base environment for a long time, the Si—O—Al bond is broken, and the gel is depolymerized, leading to the gradual reduction of the compressive strength of the filling body. This research can provide a theoretical reference for the engineering application of red mud-based filling materials in mine water.

In the process of graphite mining, due to the poor stability of graphite surrounding rock, it has brought great threat to the safety production of the mine. In view of the current situation that the spatial variability of rock mass mechanical parameters was not considered in the calculation of the instability probability of graphite ore by the existing response surface method. Firstly, based on the mathematical logic of the combination of variogram and covariance function, the correlation among variables was analyzed, and a regionalized cross-correlation random field that can reflect the spatial variability of rock mass parameters was constructed. Then, combined with the failure proximity index, the limit state equation of fractured rock mass instability was constructed. Finally, the response surface method was used to analyze the failure probability of the goaf, and the quantitative evaluation of instability risk of graphite mine goaf considering parameter spatial variation structure and response surface method was realized. The results show that the instability probability of the two sides calculated by the Monte Carlo method is 17.67%, and the instability probability of the roof is 30.19%. The instability probability of the two sides calculated by the response surface method is 17.71%, and the instability probability of the roof is 29.57%. The response surface method only uses Monte Carlo method to calculate 1/4 of the time to obtain a more accurate reliability calculation result, which simplifies the calculation process and improves the calculation efficiency.

In certain mining regions of China, the presence of thick overlying strata above the coal seam roof not only triggers rock burst disasters but also leads to significant seismic events. The occurrence mechanism of rock burst induced by thick overlying strata was analyzed. A strategy for controlling rock burst through grouting filling of the separated layer in the overlying strata was proposed. Numerical simulations and theoretical analysis were combined to investigate the load reduction and impact attenuation effects of grouting filling. The research findings indicate that in mines with thick overlying strata, the stress concentration and dynamic load intensity resulting from hanging wall effects are significantly great due to the large thickness, high strength, and considerable limit span of the rock layers. This makes them susceptible to rock burst disasters. The grouting filling technique, by filling the separated space, can support the thick overlying strata together with the surrounding rock mass, thereby reducing the sinking of the thick overlying strata. This approach effectively controls the fracture and movement of thick overlying strata, consequently reducing both dynamic and static loads and achieving the objective of minimizing dynamic overburden pressure. Numerical simulation results of grouting filling indicate that, compared to without grouting filling, the stress concentration coefficient around the separated space decreases by 8.89%,18.59%, and 35.96% when the grouting filling rates are 30%, 60%, and 90%, respectively. This decrease is associated with a substantial reduction in the height of the plastic zone and the degree of damage to the thick overlying strata, indicating that the grouting filling of separated layer can achieve the purpose of reducing load and preventing rock burst.

The anchoring operation of coal mine excavation roadway is the key factor affecting the tunneling efficiency. Accurately determining the position of anchor hole under the condition of roadway with many interference factors is one of the key links to improve the anchoring speed. At present, most of the research on anchor hole positioning has a single consideration of interference factors, and the influence of complex factors on anchor hole identification under multi-scale changes has not been studied. To this, an improved YOLOv8s anchor hole positioning method in multi-scale complex environment was proposed. Firstly, according to the actual anchoring situation of the roadway, four main factors affecting the positioning of the anchor hole, such as light intensity, dust concentration, water mist concentration and shooting distance, were summarized, and a three-level influence scale was established. The initial data set was formed by the combination of various influencing factors. Before the anchor hole identification, the image preprocessing operation was performed to optimize the overall quality of the image. Then, the YOLOv8s deep learning network model was improved, and the multi-scale hole attention mechanism (MSDA) was added to improve the feature extraction ability of the model under complex conditions. Finally, the pixel coordinates of the anchor hole center were calculated to obtain the actual three-dimensional coordinates. The results show that the average detection precision of the improved YOLOv8s model reaches 91.6%, which is 5.3 percentage points higher than that of the YOLOv8s model. The improved YOLOv8s model has better detection ability and can accurately detect the anchor hole position in the image under the interference of different scale combination influencing factors. The number of frames per second of the processed image of the improved YOLOv8s model is maintained at 171 frames, which can meet the real-time requirements of the model detection function.

In order to study the damage effect of overlying strata and the movement and instability characteristics of overlying strata under mining in close-distance coal seams, based on the mining of a close-distance coal seam in Shendong mining area, the damage theory was used to analyze the instability and deformation characteristics of the overlying strata of the close-distance coal seam under mining and the time-space evolution law of microseismic. The damage characteristics of the close-distance coal seam considering the microseismic monitoring data were discussed. The 3DEC software was used to simulate the instability and fracture of overlying strata and the law of stress transfer in close-distance coal seams under mining. The results show that the damage evolution of overlying strata increases as the distance between the upper and lower coal seams approaches. The minimum damage degree is 0.31 and the maximum damage degree is 0.77 under different monitoring schemes. There is no obvious increase or decrease trend of microseismic events in the process of overhaul, and the number of microseismic events increases continuously as the closing distance between the upper and lower coal seam working faces during coal mining. The continuous advancement of the working face of the lower coal seam causes the displacement of the overlying strata to increase, and the maximum displacement of the overlying strata is 45.9 cm. The research results are of great significance for the stability control of overlying strata in similar close-distance coal seam mining and the safe and efficient mining of coal mines.

In order to reduce the adverse effect of creep on the long-term stability of the project under the action of seepage water pressure, creep tests under different hydraulic gradients were carried out using the seepage-stress coupling servo control loading test system to explore the rheological properties and seepage characteristics of sandstone. Combined with three-dimensional digital image correlation technology (3D-DIC), the micro-cracks evolution law and deformation localization characteristics of sandstone were studied. At the same time, the crack damage characteristics of sandstone were explored based on CT scanning technology. The results are concluded as follows. Firstly, the larger the hydraulic gradient is, the larger the creep deformation is, the faster the micro-cracks growth rate is, and the more obvious the change of strain field cloud map is. Compared with the axial strain field cloud maps, the larger strain points and strain localization characteristics appear earlier in the radial strain field cloud maps. Secondly, the larger the hydraulic gradient is, the larger the strain increment is, the faster the strain change rate is, and the shorter the creep life of sandstone is. By establishing a virtual strain gauge, it is found that the strain changes inside and outside the local failure zone of sandstone are inconsistent, indicating that there are localization characteristics in the creep deformation process of sandstone. Thirdly, under the low hydraulic gradient, more pores and fissures are pressed and sealed, the seepage channel is reduced, and the flow rate is continuously reduced. Under the high hydraulic gradient, the damage is continuously accumulated, the seepage channel is increased, and the flow rate is increased. Finally, it can be seen from the CT scanning that the three main cracks penetrate the whole sample, guide the sandstone failure, and generate secondary cracks to promote crack propagation. Near the loading end of sandstone, the applied seepage water pressure is larger, and more secondary cracks are derived from the upper part of sandstone, forming a complex crack network structure.

The rock mass strength is a key mechanical parameter for the safety and stability analysis of mining engineering. Combined with the key project of small-scale mechanized mining technology in Shanhu Tungsten Mine, based on the detailed investigation of rock mass structural plane, three methods of BQ, Q and RMR were used for classification of rock mass quality and stability evaluation. Then, the rock mass strength was estimated based on quantitative GSI and Hoek-Brown Criteria to obtain accurate and reliable parameters of rock mass strength. The research results are concluded as follows. Firstly, the dominant joint plane strikes NNW-SSE or NW-SE, inclines NE or SW, and the dip angle is large. The volume joint number J_v is 7.07−9.88/m³, the integrity coefficient K_v is 0.55−0.63, and the integrity evaluation is relatively intact. Secondly, the [BQ] value, Q value, and RMR₈₉value of the limestone rock mass are 380.96, 5.58, and 59, respectively, and the grade of rock mass quality is Ⅲ or average. Thirdly, according to the BQ classification results, when the span of roadway or stope is less than 5 m, the surrounding rock can be basically stable. According to the Q classification results, the maximum unsupported span of roadway or stope is about 6.35 m. According to the RMR classification results, when the span of roadway or stope is 5 m, the average standing stability time of surrounding rock can reach 7 days. Finally, based on quantitative GSI and Hoek-Brown criteria, the Hoek-Brown strength parameters and equivalent Mohr-Coulomb strength parameters of limestone rock mass are obtained, which can provide accurate and reliable mechanical parameters for mining design and the stability analysis of rock.

In order to study the uniqueness of the displacement back analysis of isotropic viscoelastic rock mass, an analytical solution for the radial displacement of a circular roadway in a transversely isotropic viscoelastic rock mass was derived from the principle of elastic and viscoelastic correspondence principle. The uniqueness of the back analysis of displacement in transverse isotropic rock mass was studied according to the identifiable conditions of parameters. The results show that only knowing the displacement of the measuring point can not uniquely invert all the parameters. It is possible to uniquely invert other rock mass mechanical parameters only when at least 3 parameters are known in advance. The values of the vertical ground stress and the transverse ground stress have a significant influence on the identification of back analysis. The fewer the parameters to be solved, the more recognizable the parameters are. The initial ground stress parameters have the best identifiability, followed by Poisson's ratio, modulus of elasticity and viscosity coefficient on the isotropic surface, and the modulus of elasticity and viscosity coefficient normal to the isotropic surface are the worst. The research results provide a theoretical basis for the back analysis calculation of rock mass parameters.

In order to solve the problem of slow settling of iron tailings in a concentrator in Benxi, the appropriate flocculant was selected through the flocculant optimization test. The effects of slurry mass concentration, flocculant unit consumption and slurry pH on flocculant settling were investigated by single factor test. The microstructure of the settling process was observed microscopically, and the settling law of iron tailings was summarized. The results show that the natural settling basically ends at 600 min, and the sediments after reaching the critical point of settling will undergo the main consolidation stage and the secondary consolidation stage. The main consolidation stage ends at 2 000 min, and the secondary consolidation stage ends at 3 500 min. The height of the clarification layer remains stable immediately. The flocculation effect is the best when the flocculant is anionic polyacrylamide (APAM), slurry mass concentration is 15%, flocculant unit consumption is 20g/t, and slurry pH=9. Under this condition, the solid content of 10 min is 233.13 mg/L, and the settling rate of 10 min is 67.15%.

In order to reduce the adverse effects of loading dust on the occupational health of workers in low-concave open-pit mines and formulate effective dust reduction measures, based on the theory of gas-solid two-phase flow, the Euler-Lagrange model and Fluent numerical simulation software were used to explore the influence of different wind speeds on the diffusion and mass concentration distribution of loading dust near the side slope of low-concave open-pit mines. The results show that the flow separation occurs after the airflow passes through the steps, forming a low-speed turbulent zone, a counterclockwise structural vortex and a clockwise small vortex in the carriage, which makes the flow field structure near the －12 m horizontal mining working face and the carriage of the open-pit mines very complicated. With the increase of wind speed, the aggregation time of loading dust in the carriage is shortened, the diffusion rate of loading dust is increased, the distance of diffusion pollution effect along the X-axis is increased, and the maximum dust mass concentration aggregated in the structural vortex is significantly reduced. The dust mass concentration in the carriage is higher than 100 mg/m³, and the dust mass concentration at the height of the respiratory zone decreases along the way, and the decrease of dust mass concentration is reduced. According to the numerical simulation results and the occupational exposure limit of 8 mg/m³, the area of the dust pollution is determined to be within 15 m in front of the front of the car. Measures are formulated such as using fog gun trucks, sprinkler trucks and equipping protective equipment, and good dust removal effect is obtained.

Aiming at the dust diffusion phenomenon in the process of grab unloading, the dust-isolation with air curtain and negative pressure suction technology were combined, and the CFD-DEM two-way coupling simulation method was used to study the comprehensive dust suppression system of dust-isolation surrounded by air curtain and negative pressure suction. Through the performance simulation study of the dust-isolation surrounded by air curtain, it is concluded that the effective block of dust can be achieved when the jet velocity of the air curtain is greater than 8 m/s. At the same time, based on the theory of negative pressure suction, the relationship between the mass flow of air flow of the suction port and the unloading time was deduced by CFD fluid mechanics method, and the simulation model of grab unloading was established. The flow field distribution of the unloading plane and the mass flow rate of dusty air flow escaping from the dust-isolation hopper mouth plane were extracted by simulation to reflect the movement of the dusty air flow inside the hopper. The movement law and dust suppression effect of unloading dust before and after the installation of air curtain and negative pressure suction device were compared and analyzed through tsets. The results show that compared with traditional grab, the instullation of air curtain and negative pressure suction device reduced the maximum mass concentration of dust at the hopper mouth by 738.3 mg/m³, which is reduced by about 95.3%, and the complete settlement time of dust is shortened by 60%. The results provide a reference for efficiently solving the problem of dust diffusion in unloading.

At present, the traditional total ventilation control method on the fully mechanized heading face fails to realize dynamic control of dust reduction, and the ventilation environment in the area of personnel activity is not considered in the dust reduction process, resulting in dust accumulation. Therefore, a finite element calculation model was established for the coupling of air flow and dust gas-solid, and underground verification was conducted. According to the dust migration and distribution law and the activity range of underground personnel, different areas of personnel activity were divided. The dust mass concentration sample data under different airflow intelligent control schemes were obtained by simulation, and the data were discretized by K-means algorithm. Based on the immune genetic algorithm, the dust reduction scheme was used as the antibody, and the dust mass concentration in different areas of personnel activity was used as the antigen. The acquisition algorithm of the intelligent control of air flow and dust reduction scheme for the different areas of personnel activity were compiled. Taking a mine in northern Shaanxi Province as the research object, the optimal dust reduction scheme for the personnel in the dust accumulation area (in the range of 5−15 m) is 1.2 m outlet aperture, 5° horizontal deflection, and 5 m from the head. The dust reduction effect of the scheme was tested and verified. The result show that, after the application on the experimental platform, the average dust mass concentration in dust accumulation area is reduced from 163.77 mg/m³ to 91.32 mg/m³, which is reduced by 44.24%; the dust concentration at the driver's position is reduced from 161.94 mg/m³ to 78.90 mg/m³, which is reduced by 51.28%. After the application in underground, the average dust mass concentration in dust accumulation area is reduced from 182.81 mg/m³ to 113.94 mg/m³, which is reduced by 37.67%; the dust mass concentration at the driver's position is reduced from 179.65 mg/m³ to 101.27 mg/m³, which is reduced by 43.63%.

To improve the problem of poor soil nutrients and limited carbon sequestration capacity in the arid mining area of Northwest China, combined with field experiment and static box method, multi-source solid waste (coal gangue and sludge compost) combined with carbonate-mineralization microbe were used to improve sandy degraded soil in coal mining subsidence area. The results show that the addition of multi-source solid waste and carbonate-mineralization microbe promote the growth of alfalfa and the development of its roots, and increase the carbon and nitrogen content of alfalfa. Multi-source solid waste combined with carbonate-mineralization microbe significantly increases soil carbon and nitrogen content and soil microbial carbon and nitrogen metabolism related enzyme activities, and the improvement effect of multi-source solid waste combined with carbonate-mineralization microbe is better than that of single application of bacteria. After the addition of solid waste and carbonate-mineralization microbe, the net ecosystem exchange rate (NEE) of sandy soil decreases, and the gross primary productivity (GPP) of the ecosystem increases. The structural equation model shows that the addition of multi-source solid waste and carbonate-mineralization microbe is an important factor affecting GPP. Therefore, multi-source solid waste combined with carbonate-mineralization microbe has the application potential of improving quality and efficiency, carbon sequestration and emission reduction in soil remediation in arid mining areas in Northwest China.

Regarding the problem of collecting the impact frequency of open-pit down-the-hole drill rigs, based on the characteristics of the drilling acoustic signals of the TAIYE-390-Ⅱ split hydraulic open-pit down-the-hole drill rig, the impact frequency acquisition system and acquisition method were analyzed. Under the condition of constant wind pressure and constant axial pressure, drilling acoustic experiment and blasthole peep experiment were carried out to study the stability of the system and the feasibility of impact frequency in the identification of rock mass structural plane. The results show that 6 kHz is the most obvious signal dominant sampling frequency of the impact section waveform. The impact frequency acquisition method of acoustic signal in drilling process based on Hilbert transform, variational mode decomposition (VMD) and Savitzky-Golay filter can accurately extract the real-time impact frequency of drilling, and the error is controlled at 1 Hz. The impact frequency has a relatively obvious response to the rock mass structure. When encountering various structural planes, the value of the impact frequency will decrease by 1−3 Hz. The research results have important theoretical significance and application value in aspects such as the collection of the impact frequency of down-the-hole drills and the identification of rock mass structural planes.

In order to improve the magnetic field performance of the flat magnetic separator and reduce its manufacturing costs, the finite element method, response surface method, and Nondominated Sorting Genetic Algorithm Ⅱ (NSGA- Ⅱ) were used to perform multi-objective optimization analysis on the structural parameters of the planar extrusion magnetic system. Firstly, a response surface analysis experiment was conducted using the structural parameters of the extrusion magnetic system as variables. The response values of the area field intensity and magnet efficiency density were calculated through numerical simulation, and a regression model of the objective function was constructed. The fitting accuracy of each regression model was evaluated using analysis of variance. Then, a multi-objective optimization model was constructed with the objectives of area field intensity, magnet efficiency density, and number of magnetic poles, and a Pareto solution set was calculated to obtain a series of optimization schemes. The research results indicate that the regression model of area field intensity and magnet efficiency density has a high fitting accuracy and a good predictive ability. The Pareto solution set reveals a conflicting relationship between the area field intensity with the efficiency density and number of magnetic poles of the magnet. The error range between the multi-objective optimization model with the simulation results is 0.73%−5.30%, which verifies the reliability of the multi-objective genetic algorithm in optimizing the design parameters of the planar extrusion magnetic system.

Las Bambas is a high-altitude mine with remote geographical location and harsh environment. Based on the core requirements of Las Bambas Mine towards intelligent mine and many problems of unfavorable directly deploying a large number of personnel to participate in mine operation on site, all the functional support on the Las Bambas Mine operation value chain was analyzed, the existing intelligent system was reviewed and optimized, the digital operation center (DOC) of Las Bambas Mine was established, and its implementation effect was summarized and analyzed. The results show that the establishment of mine digital operation center improves the digitization, automation and intelligence level of mine operation, simplifies the approval process of staff, and realizes 100% remote integrated operation. The digital operation center realizes the safety integrated management of personnel, equipment and environment, the efficiency is 97.7%, the accuracy of fatigue prediction is 94.7%, and the number of heavy trucks hitting the primary crusher structure is reduced by 90%. The role changes of 20 positions in mine production involve the on-site migration of 63 employees, which realizes the remote processing of process integration and on-site process scheduling. The research results can provide reference for mines in the same type of high-altitude and remote areas in terms of personnel reduction, remote office scheduling and digital operation.

In response to the characteristics of a tungsten-molybdenum-bismuth polymetallic mine in Hunan Province, which contains magnetic iron, low and fluctuating molybdenum grade, and high content of mudstone gangue, an experimental research was conducted to optimize the beneficiation process and reagent system in order to improve the beneficiation recovery rate of molybdenum. The research results show that adopting the process of "magnetic separation followed by flotation—molybdenum-bismuth iso-floatability flotation—bulk flotation of residual sulfide ore", good mineral processing indicators can be achieved by taking CD-N as the regulator, B-8 combined with butyl xanthate as the sulfide ore collector, and F6 as the frother. The molybdenum closed circuit test obtained a molybdenum-bismuth mixed concentrate with Mo grade of 3.46%, Bi grade of 2.03%, Mo recovery rate of 85.40%, and Bi recovery rate of 80.05%. Compared with the on-site production conditions, the recovery rate of molybdenum is increased by nearly 5 percentage points, achieving efficient recovery of molybdenum. The new reagent system doesn't affect the subsequent scheelite flotation, providing a technical basis for the subsequent expansion and renovation of beneficiation plant in the tungsten-molybdenum polymetallic mine.

The main components of iron concentrate produced by Hualian Zinc Indium Concentrator are magnetite and pyrrhotite. There are some problems such as excessive sulfur content, poor quality, low sales price and high loss rate of tin metal in this iron concentrate. The efficient separation of pyrrhotite and magnetite was realized by the process of iron rough concentrate + low-intensity magnetic separation + pre-demagnetization + grading regrinding + pre-demagnetization + flotation desulfurization + magnetic separation. Finally, a high-quality iron concentrate with iron grade of 66.62% and sulfur content of 0.65% was obtained, and a high-iron sulfur concentrate with sulfur content of 25.61%, sulfur recovery rate of 96.06% and iron content of 59.52% was produced. At the same time, the loss rate of tin in iron concentrate was reduced, and a sulfur ore with a tin enrichment ratio of 3.69 times was produced, thereby reducing the loss of tin metal.

Due to the unique coal forming environment, the contents of alkali metals and alkaline earth metals in Zhundong coal are high, and some mining areas are accompanied by problems such as high iron and high calcium. These elements can cause boiler slagging and pollution during coal combustion, greatly limiting the development and utilization of Zhundong coal. In order to achieve efficient and clean utilization of Zhundong coal and fundamentally reduce the content of alkali metals and iron in Zhundong coal, it has been demonstrated that Fe₂O₃ in coal ash mainly comes from associated minerals of coal. Therefore, by sorting and reducing the content of coal ash, iron elements in coal can be removed to a certain extent. Several mature sorting technologies were compared and analyzed, it was found that due to the brittle nature of coal in the West Black Mountain mining area of Zhundong coalfield and its susceptibility to water, and it is difficult to improve its quality and utilization through wet sorting technology. The cost of magnetic separation technology equipment is high and the feeding particle size is small, which not only increases the crushing cost, but also doesn't conform to the actual production and sales situation of coal mines. The profit level and production of the composite dry sorting machine are relatively high, which meets the actual production needs of coal mines. It is recommended to use the the composite dry separation technology to improve the quality and reduce iron content of raw coal in the mining area. The composite dry separation technology can reduce about 30% of Fe₂O₃ of the raw coal ash in the research area, and the sorted clean coal can be subjected to powdering treatment to reduce the iron content in the clean coal to below 20%, thereby meeting the market demand.

In order to improve the level of on-line detection of ash in coal slime flotation process, the prediction of ash content of tailings in coal slime flotation process was studied, and the prediction model of ash content of flotation tailings based on LightGBM optimized by genetic algorithm was established. Through the collected production data, including slurry flow, concentration, foaming dose, collection dose and dry slime amount, the model training data set was constructed and the model was tested and verified. The experimental results show that the average absolute error of the prediction results of the model is 0.72, which is 11.1% higher than that of the unoptimized LightGBM model. Compared with other models, the average absolute error of the prediction results of the GA-LightGBM model is reduced by 15.8%, which further proves the validity of the model in the prediction accuracy of ash in coal tailings and provides a new technical support for the realization of intelligent flotation.