Large-scale continuous mining of deep ore bodies is the frontier research direction of deep mining in the future. Aiming at the problem of mutual restriction between the traditional intermittent mining operation mode and the deep intelligent and efficient mining of deep hard rock deposits, a continuous mining operation mode of parallel mining and filling was proposed, which used flexible isolation layer to realize the parallel filling and continuous mining process. The strength distribution of filling body in parallel filling process of high-stage large stope was analyzed by means of theoretical calculation formula and FLAC3D numerical software, and the strength requirements of filling body at different heights of high-stage stope were determined. PFC discrete element software was used to analyze the flow law of ore-filling granular and the deformation damage characteristics of isolation layer in parallel filling and continuous ore drawing. The results show that in the parallel filling and continuous ore drawing process, the 28 d consolidation bearing strength of the filling body at the top and bottom of the stope should be greater than 8 MPa. With the filling and ore drawing, the maximum load of the isolation layer is 57 kPa when it is close to the funnel mouth of the ore drawing. At this time, the isolation layer has obvious concave deformation, and the damage near the pillar area on both sides increases, resulting in obvious tensile and compressive damage. The study can provide reference for the continuous operation of deep ore body mining.

To study the phenomenon of rock burst in deep rock roadway, the true triaxial rock burst test machine was used to study the phenomenon of rock burst induced by cyclic dynamic disturbance under different axial stresses in semi-circular arch roadway with prefabricated straight wall, and the acoustic emission technology was used to monitor the failure process of roadway. Through the rock burst test, it is found that the greater the initial axial static stress, the higher the degree of rock deterioration, the shorter the disturbance time required for rock burst, the faster the cumulative energy rate of the sample, and the more severe the rock burst. The results show that when the axial stress exceeds 76.5% of the peak stress of the rock roadway, the rock burst will occur after the cyclic dynamic disturbance is applied to the specimen. The failure mode of rock roadway is tension-shear combined failure, and the failure mode of crack propagation is closely related to axial stress and dynamic disturbance. Acoustic emission cumulative ringing count is used to describe the degree of rock deterioration, and it is found that the degree of rock deterioration under dynamic disturbance is positively correlated with the initial axial static stress.

A gently inclined and multi-layer poor ore vein contains lead-zinc, magnetite and sulfur-copper minerals at the same time. Based on the characteristics of the ore body and its low grade, a pseudo inclined strip roadway filling mining method was proposed for safer and more economical mining. FLAC3D software was used to simulate and analyze the roof displacement, pillar stress, and plastic zone distribution under different approach widths. Research results show that the pseudo inclined strip roadway filling mining method can effectively reduce the loss and impoverishment of ore, greatly reduce mining and cutting engineering amount, increase the production capacity of the stope, and achieve separate mining and transportation of different types of minerals. It can be flexibly applied to complex and variable gently inclined ore bodies. After numerical simulation analysis, the optimal approach width for this mine is determined as 5 m or 6 m.

In view of the optimal selection of mining methods in underground metal mines, a game theory-subjective and objective multi-attribute combined weighting model was constructed. Taking the optimal selection of mining methods at the Sijiaying Iron Mine as an example, under the criteria of environment, economy, technology, and safety, 11 indicators closely related to mining methods were selected. The improved analytic hierarchy process (AHP) and CRITIC methods were used to determine the subjective and objective weights of each indicator, respectively. By applying game theory, the subjective and objective weights were integrated to obtain the comprehensive weights for all indicators, providing a basis for the selection of mining methods. The game theory-subjective and objective multi-attribute combined weighting model was used for optimal selection between two alternative mining methods. The comprehensive membership degree of the sub-level open stoping method with subsequent filling is 0.711, while that of the block caving method with subsequent filling is 0.692, with the former being chosen as the optimal scheme. The research results can offer a beneficial reference for decision-making in mining method optimization.

To solve the problem of roof instability or insufficient production capacity caused by unreasonable values of stope structure parameters, an iron ore mine in Hebei Province was selected as the background to optimize the stope structure parameters and analyze their sensitivity. Firstly, a rock mass quality investigation was conducted and the extended Mathews stability chart method with stable probability was used to preliminarily determine the width and length range of the stope. Then, FLAC3D numerical simulation was used to explore the deformation law of the maximum displacement of the stope roof with the variation of structure parameters. Combined with response surface method, a prediction model for the displacement of the stope roof was constructed, and the sensitivity of the single factor affecting the displacement of the stope roof and their interaction relationship were explored. Finally, considering safety and block size, the stope structure parameters were optimized, and industrial experiments were conducted to verify the rationality of the results. The results indicate that the overall rating of the ore body is grade V, and the rock mass quality is very poor. The sensitivity of the roof displacement of the stope to various parameters, from high to low, is as follows: stope width, stope length, and stope height. The optimal stope structure parameters for this ore body are a width of 12 m, a length of 36 m, and a height of 60 m. When using the structure parameters for recovery, the contour of the goaf is relatively flat and stable. The research results can provide theoretical basis for selecting reasonable stope structure parameters and correctly coordinating stope safety and production capacity.

To study the influence of seepage field on the freezing temperature in the loose accumulation rock group of the intake air shaft in the gold mining area in the northern sea area of Sanshan Island, Laizhou City, based on the flow velocity measurement and the material parameters of the rock group, the COMSOL finite element numerical model was established. The intersection time of the three-circle freezing construction of the vertical shaft and the formation time of the freezing curtain were predicted, and the reliability of the design and numerical simulation of the three-circle freezing construction scheme of the vertical shaft was verified by an engineering example. The results show that due to the high flow velocity of coastal groundwater, the intersection line of the inflow surface is shaped like teeth during the freezing process. The low temperature of the freezing pipe has a significant impact on the downstream under the seepage action, and the freezing curtain develops asymmetrically and shifts to the downstream of seepage. The three-circle freezing design reduces the temperature of the shaft excavation area to below the phase transition temperature of −1 ℃ after 18 days of freezing. In the engineering verification, the intersection time and the freezing curtain formation time are 25 d and 36 d, respectively, which are consistent with the numerical simulation results. The research results can provide reference for similar projects.

Thickening and dewatering of tailings is a key link in the tailings filling process. In order to explore the thickening and dewatering performance of tailings in a mine, static and dynamic flocculation settlement tests of tailings were carried out according to the basic physicochemical properties of tailings. The static flocculation settlement tests were designed with the mass concentration of tailings slurry, the flocculant type and the flocculant content as the influencing factors and the settlement rate as the research index. The dynamic flocculation settlement tests were designed with feed rate, feed mass concentration and flocculant content as influencing factors, and solid content of overflow water, underflow mass concentration and settling velocity of tailings as research indexes. Based on response surface analysis method, the dynamic flocculation settlement law of total tailings under the interaction of multiple factors was revealed. Firstly, through the static flocculation settlement tests, the optimal type of flocculant was determined as CKFA02, the optimal content of flocculant was determined as 20 g/t, and the optimal feed mass concentration of tailings slurry was determined as 10%−12.5%. Secondly, according to the response surface model constructed based on the dynamic flocculation settlement tests, the maximum influencing factors on the underflow mass concentration, solid content of overflow water, and settling velocity of tailings are the slurry feed rate. The interaction between slurry feed rate and feed mass concentration has the greatest impact on the underflow mass concentration, while the interaction between slurry feed rate and flocculant content has the greatest impact on the solid content of overflow water and settling velocity of tailings. Thirdly, the optimal settlement parameters are the slurry feed rate of 0.55 t/(m²·h), feed mass concentration of 11.12%, flocculant content of 30 g/t. Under the optimal flocculation settlement parameters, the underflow mass concentration is 60.6%, the solid content of overflow water is 251.4 mg/L, and the settling velocity of tailings is 58.06 mm/s.

There are significant differences in mechanical properties and failure modes among backfill with different sizes. In order to study the size effect of backfill, the uniaxial compression experiments were conducted on four groups of backfill specimens with different sizes, and an acoustic emission meter was used to monitor the energy release during the loading process. Numerical simulation was used to simulate and verify the compression failure of the specimens and study the size effect and damage characteristics of cylindrical backfill specimens with different sizes. Finally, the scanning electron microscope tests were carried out on the cylindrical specimens of gangue cemented backfill with different sizes, and the microscopic morphology difference of different sizes of specimens was observed. The results show that the uniaxial compressive strength of the specimen is inversely proportional to the size of the specimen. The small size specimen is dominated by shear failure. When the size of the specimen increases to a certain extent, it shows a certain tensile failure. With the increase of the size of the specimen, the specimen shows a more obvious size effect. The acoustic emission characteristic of the cylindrical specimen can be divided into the initial preparation stage, the acoustic emission increasing stage and the acoustic emission decreasing stage. The acoustic emission activity of the specimen with small size is more intense than that with the large size. The larger the size of specimen, the more weak points in the specimen, and the worse the cementation ability of the specimen. The research results can provide a scientific basis for the determination of backfill parameters of different size structures in gangue cemented filling.

In order to solve the problems such as high block rate, severe damage to the filling bodies and top pillars on both sides during the two-step mining process, and high ore impoverishment rate encountered during the mining by sublevel drilling and stage open stope with subsequent filling method in Sanguikou lead-zinc mine, optimization research was conducted on the original blasting parameters. Using a diameter of the blast hole of 76 mm and based on the analysis of rock drillability and blastability, through theoretical calculation, it is determined that the row spacing is 1.8 m and the hole bottom spacing is 2.1 m; alternatively, the row spacing is 1.9 m and the hole bottom spacing is 2.0 m. According to on-site industrial tests, compared with the stope using the original blasting parameters, the optimized blasting parameters reduced ore impoverishment rate by 19.8%, ore loss rate by 4.6%, the explosive consumption by 12.2%, and the block rate by 34.8%. The simulation analysis of the blasting effect before and after optimization of blasting parameters was conducted using LS-DYNA finite element software, and the simulation results showed that when using optimized blasting parameters for blasting, the ore block rate is lower, and the damage to the filling body on both sides, top pillar, and rock drilling roadway arch line is minimal.

Earthquakes are one of the main causes leading to dynamic instability of tailings dams. Based on the pseudo-dynamic method combined with the Swedish arc method, the evaluation indexes of dynamic stability of tailings dams can be quickly determined. To improve the computational efficiency of the pseudo-dynamic method in the evaluation of slope earthquake stability, a separated critical initial phase search strategy was introduced, and a fast pseudo-dynamic method was proposed. The traditional pseudo-static method, the pseudo-static method considering the amplification factor, and the fast pseudo-dynamic method were applied respectively to evaluate the seismic stability of a tailings dam in Xizang from two angles of safety factor and failure probability. The results of numerical analysis show that the safety factors obtained by above three methods all meet the minimum stability requirements. In the view of the safety factor and the sliding area comprehensively, the results obtained by the pseudo-static method considering the amplification factor tend to be conservative. The influence of P-wave velocity on the calculation results is small. With the increase of S-wave velocity, the safety factor obtained by the fast pseudo-dynamic method gradually decreases, the failure probability gradually increases, the number of instability sliding surfaces gradually increases, and the risk sources of earthquake instability of tailings dams increase. The research results have a guiding significance for the evaluation of earthquake stability of tailings dams.

The traditional theoretical methods mostly use semi-quantitatively to analyze the safety thickness of the goaf roof, which can not fully reflect the stress and failure mode of the roof. Therefore, the cusp mutation theory was introduced to study the safety thickness of the goaf roof, the research model of the safety thickness of the roof was established, and the formula of the minimum safety thickness of the roof was derived. Based on the occurrence status of goaf in Dabaoshan Mine, the theoretical values of safety thickness of goaf roof under different lithology and different span conditions were calculated. Finally, the formula was verified by the traditional theory and the finite element numerical simulation method. The research results show that it is feasible to introduce the cusp mutation theory into the study of the safety thickness of the goaf roof, and the derived formula of the minimum safety thickness of the goaf roof is reasonable and reliable. Under the conditions of the slightly weathered limestone, slightly weathered secondary dacite-porphyry, copper-sulfur ore body, and sandstone-rock group in Dabaoshan Mine, the safety thickness of the goaf roof calculated based on the cusp mutation theory is 7.3 m, 12.5 m, 9.5 m, and 22.1 m, respectively, which can be used as the basis for on-site goaf treatment.

In order to improve the rationality of mechanical parameters of tunnel surrounding rock, a new inversion model of surrounding rock parameters was proposed based on a tunnel project with a super large-section in Zhuhai. After the initial samples were generated based on Latin hypercube sampling (LHS), the parameter sensitivity analysis was carried out to determine the key parameters of the surrounding rock and improve the sample structure. Then, the whale optimization algorithm (WOA) was used to optimize the number of hidden layer nodes, the initial weights and the thresholds of the extreme learning machine (ELM) to form the LHS-WOA-ELM inversion model. The inversion parameters were substituted into FLAC3D to calculate the displacement and compare with the field measured data. The results show that the parameter sensitivity analysis based on LHS can investigate the co-variation of multi-parameters with fewer samples, and determine the main parameters affecting the displacement of surrounding rock as elastic modulus E, cohesion c and internal friction angle φ. Compared with WOA, ELM and BP algorithm models, the difference between the calculated displacement values obtained by LHS-WOA-ELM inversion model and the measured displacement values is smaller, indicating that the inversion analysis method can well reflect the nonlinear and uncertain characteristics between the surrounding rock parameters and deformation, and further improve the accuracy and efficiency of the surrounding rock inversion in tunnels with super-large section, which can provide a reference for determining the design parameters of underground caverns and mining projects.

In order to reveal the influences of super-thick and hard strata on abutment pressure and the evolution law of energy distribution in stope, a typical mining area of Yangliu Coal Mine was taken as the research object, and the variation law of abutment pressure and energy evolution process were simulated by numerical simulation method. The results are concluded as follows. (1) When there are super-thick and hard strata in the overlying strata, the advance abutment pressure in the middle and both sides of the working face is increased by about 9% and 5% respectively compared with that without super-thick and hard strata. This shows that when there are super-thick and hard strata in the overlying strata, the middle and both sides of the stope are in a high stress state for a long time. When the stope is disturbed by external force, it is more likely to lead to the occurrence of dynamic disasters such as mine earthquake and rock burst. (2) When there are super-thick and hard strata in the overlying strata, the change curve of the advance abutment pressure of the stope shows a cliff-like decline after breaking. When there are no super-thick and hard strata in the overlying strata, the change curve of the advance abutment pressure of the stope is gentler than that of the former. (3) With the continuous advancement of the working face distance, the peak value of the abutment pressure of the free side is increased by 3.60 MPa and 3.39 MPa respectively compared with the peak value of the abutment pressure of the mining side when there are or are not super-thick and hard strata in the overlying strata. The change trend of the side abutment pressure of the two is basically the same, but the side abutment pressure of the free side of the roadway is obviously larger than the lateral abutment pressure of the mining side of the roadway. This shows that the existence of super-thick and hard strata makes the stress concentration, roadway mining will be more prone to damage. (4) The super-thick and hard strata will cause great impact on the stope after breaking. Compared with the stope without super-thick and hard strata, the damage degree is more severe, the elastic energy released is more, and the influence range is more extensive.

Obtaining the stability level of rock mass is of great significance to the deep mining of ore body, surrounding rock support and filling of goaf. Based on the engineering geological conditions of Zhongguan Iron Mine, the basic quality BQ values of rock mass at the measuring points were determined through laboratory rock mechanics basic property test, field rock mechanics test, field rock joint investigation and in-situ stress test. Using the data processing and spatial analysis function of ArcGIS software, the spatial distribution prediction model of rock mass quality in the study area was established through Kriging interpolation technology. The rock mass quality of –230 m horizontal ore body was predicted and analyzed using the model, and the field measurement verification was carried out. The results show that the prediction results of the spatial distribution of rock mass quality are in good agreement with the actual situation. The basic quality BQ value of the –230 m level ore body in Zhongguan Iron Mine is 57.843 - 347.573, which is in the fourth and fifth grades. The ore body quality is poor, easy to break and unstable. The spatial distribution prediction model of rock mass quality can provide a method for studying the stability level of rock mass under the condition that rock mass engineering is not fully exposed, and also can build a theoretical basis for the safe mining of Zhongguan Iron Mine in the future.

The underground rock body is often affected by external factors, after repeated cycles of loading and unloading, it will lead to the increase of internal cracks in rock and the change of local stress environment. Therefore, the triaxial graded cyclic loading and unloading tests with different upper limit stresses were carried out on sandstone, and the damage mechanical properties and the laws of energy evolution of sandstone were obtained. The test results show that under the conditions of graded cyclic loading and unloading, the stress-strain curve of sandstone is characterized by hysteresis loops and downward bending, and the hysteresis loops are gradually enlarged with the increase of stress. Under the cyclic loading and unloading with different upper limit stresses, as the number of cycles increasing, the axial elastic strain and axial plastic strain of sandstone show linear relationships with the number of cycles, while the sudden drop of axial plastic strain indicates that the internal pore cracks of sandstone are compacted rapidly. Meanwhile, the input energy and elastic energy curves are very similar during the cycling process, showing an upward trend of nearly exponential curve. Dissipation energy grows relatively slowly in the initial cycling stage, which indicates that the original cracks in the sandstone are compressed and closed; while in the mid-cycling stage, the dissipation energy shows a nearly linear growth trend, which indicates that the rock samples are in the stage of stable expansion of the cracks. The dissipation energy ratio shows a sudden decrease in the initial cycling stage; while in the mid-cycling stage, it maintains an approximate horizontal trend. In addition, under the graded cyclic loading and unloading, there is a linear relationship between the degree of damage to sandstone and the number of cycles, indicating that the number of load cycles has a significant impact on the degree of damage to sandstone.

To study the mechanical properties of marble after damage caused by dynamic and static combined loads, the improved split Hopkinson pressure bar device was used to carry out dynamic and static combined load damage tests on marble at four axial compression levels (0, 18 MPa, 36 MPa, 54 MPa) and three impact velocity levels (8 m/s, 9 m/s, 10 m/s). The uniaxial compression acoustic emission tests on the damaged marble was carried out. The results show that under the action of static and dynamic combination, with the increase of axial static pressure, the dynamic peak stress, dynamic elastic modulus and wave velocity of marble increase firstly and then decrease. The absorption energy is closely related to the axial static pressure. When the axial static pressure is low, the energy required for the closure of microcracks in the rock is mainly obtained from the impact bar. With the increase of axial static pressure, the proportion of energy obtained from the impact bar gradually decreases. With the increase of axial static pressure, the uniaxial compressive strength and elastic modulus of rock after damage caused by dynamic and static combined load increase firstly and then decrease. When the axial static pressure is 18 MPa, the uniaxial compressive strength and elastic modulus of rock reach the maximum value. Appropriate axial static pressure can effectively improve the ability of rock to resist dynamic load and reduce rock damage. In the middle and later stages of the uniaxial loading failure process, the less the number of high-frequency acoustic emission signals (>400 kHz) of the rock with small damage degree, the more the number of medium and low-frequency acoustic emission signals (165 - 205 kHz). The proportion of acoustic emission signals at 165−205 kHz increases firstly and then decreases during the whole loading process, which can be used as a precursory feature of rock failure.

In the process of hot dry rock mining in enhanced geothermal system, high temperature and cyclic cooling will lead to damage the thermal reservoir rock mass, change its physical and mechanical properties as well as microstructure, and affect the permeability of rock mass and mining efficiency. The granite samples after high temperature treatment at 400 ℃ were subjected to cyclic cooling treatment by different cooling methods. The shear permeability tests were carried out under different normal stresses. The shear fracture surface of granite was analyzed by three-dimensional morphology and scanning electron microscopy. The results show that the shear strength and shear displacement of granite increase with the increase of normal stress. The shear strength decreases with the increase of cyclic cooling times, and the shear strength of water-cooled samples decreases more obviously. The cohesive force decreases with the increase of cyclic cooling times, and the internal friction angle does not change significantly. The initial permeability decreases with the increase of normal stress, and the initial permeability of water-cooled samples is 1-2 orders of magnitude higher than that of natural cooling samples. The shear displacement corresponding to the minimum permeability increases firstly and then decreases with the increase of cyclic cooling times, and increases with the increase of normal stress. With the increase of cyclic cooling times, the intergranular cracks of the natural cooling sample increase, the width of the transgranular cracks increases. The secondary cracks of the water-cooled sample increase and crystal fracture occurs. The research results can provide theoretical basis and technical support for hot dry rock mining.

In order to investigate the crushing properties and energy conversion law of magnetite ore under impact load, taking magnetite ore with different iron-silicon ratios as the research object, the impact crushing test on magnetite ore with different iron-silicon ratios was carried out using split Hopkinson pressure bar to analyze the destructive deformation characteristics, compressive strength and energy conversion law of magnetite ore under different incident stresses, and to reveal the macro-micro crushing mechanism by combining with scanning electron microscope technology. The results show that under the impact load, the stress-strain curves of magnetite ore with different iron-silicon ratios do not have a compression-density phase, and the elasticity modulus, peak stress, and dynamic compressive strength all decrease with the increase of the iron-silicon ratio, and the dissipation energies of the three iron-silicon ratios of magnetite ore increase with the increase of the iron-silicon ratio and the incident energy. With the increase of incident stress, the diameter of the ore fragments is decreasing, the intergranular cracks and transgranular cracks in magnetite ore are increasing, and the width and length of cracks increase with the increase of iron-silicon ratio. When the incident stress is the same, the ore fragments with a large iron-silicon ratio are smaller than those with a small iron-silicon ratio. Therefore, in the actual production of mines, magnetic iron with different iron-silicon ratio can be crushed in batches, which can improve the energy utilisation to a certain extent.

To effectively ensure the long-term stability of the extension section of the auxiliary inclined shaft in a mine of northern Shaanxi, ABAQUS software was used to analyze the influence of parameters such as thread spacing, anchorage length and borehole diameter on the bearing performance of the bolt, and reasonable anchorage parameters were selected. FLAC3D software was used to simulate the bolt support schemes of three kinds of spacing, and the optimal bolt spacing was determined by the displacement and plastic zone distribution. On this basis, field tests and surrounding rock deformation monitoring were carried out. The results show that the maximum tensile force of the bolt under 10 mm thread spacing is only 7.9 kN different from that under 8 mm thread spacing. Considering the production cost, the thread spacing of the bolt is determined to be 10 mm. The maximum anchorage force of the bolt increases with the increase of the anchorage length and the borehole diameter. After exceeding the critical value, the anchorage length and the borehole diameter have little effect on the anchorage force. Finally, the reasonable anchorage length is 800 mm and the borehole diameter is 28 mm. The control effect of surrounding rock with bolt support spacing of 1 200 mm and 1 000 mm is not much different. In order to improve the construction efficiency, the bolt spacing is determined to be 1 200 mm. The field practice shows that after using the optimized anchorage and support parameters, the average anchorage force of the bolt is greater than 150 kN, and the surface deformation of the surrounding rock is less than 25 mm, which can ensure the stability of the roadway and verify the rationality of the anchorage and support parameters.

To explore the acid corrosion resistance of zinc-infiltrated anchor bolt, the corrosion characteristics and mechanical properties of zinc-infiltrated anchor bolt in acidic environment were studied. Firstly, the immersion corrosion tests on ordinary anchor bolts and zinc-infiltrated anchor bolts were carried out, the corrosion kinetic model of zinc-infiltrated anchor bolt was constructed, and the deterioration law of mechanical properties and corrosion failure mechanism of zinc-infiltrated anchor bolt were analyzed. Secondly, the influence of anchor bolt corrosion degradation on the stability of roadway surrounding rocks was analyzed by Abaqus numerical simulation. Finally, the acid corrosion resistance of the zinc-infiltrated anchor bolt was tested by engineering application. The results show that under the same corrosion conditions, the acid corrosion resistance of zinc-infiltrated anchor bolt is significantly better than that of ordinary anchor bolt, and the stability of roadway surrounding rocks supported by zinc-infiltrated anchor bolt is significantly higher than that of ordinary anchor bolt supporting roadway. In the acidic environment, the ordinary anchor bolt is characterized by accelerated corrosion, and the zinc-infiltrated anchor bolt is characterized by uniform corrosion. After corrosion for 100 days, the yield strength, tensile strength and elongation rate of ordinary anchor bolt decrease by 6.50%, 6.37% and 15.85% respectively, and the tensile fracture form changes from ductile fracture to ductile-brittle mixed fracture. The yield strength, tensile strength and elongation rate of the zinc-infiltrated anchor bolt are decreased by 2.85%, 1.45% and 7.97% respectively, and the tensile fracture form is still ductile fracture. After the occurrence of corrosion, the displacement of the roof and two sides of the roadway supported by ordinary anchor bolts is increased by 50.07% and 52.50% respectively, and the stress is increased by 36.85% and 27.41% respectively. The displacement of roof and two sides of roadway supported by zinc-infiltration anchor bolts is increased by 21.07% and 22.06% respectively, and the stress is increased by 16.37% and 20.54% respectively. The results of engineering application show that the use of zinc-infiltration anchor bolt for roadway support can effectively prolong the life of anchorage support and ensure the safety of roadway support.

Through relevant calculation, the effectiveness of the design measures of a tailings pond was verified. Based on the GEO-SLOPE numerical simulation, the seepage and stability of the tailings pond under different working conditions were comprehensively evaluated. The results show that under the flood control standard of once in five hundred years, the discharge capacity of the flood interception ditch on east and west sides of the tailings pond and the discharge capacity of the spillway in the tailings pond area can meet the requirements. Through seepage calculation and analysis, the effectiveness of seepage control measures of tailings pond is verified. HDPE geomembrane and drainage system have good anti-seepage effect. Under the calculation of three working conditions, the anti-sliding stability of the downstream slope of the tailings pond can meet the design standards. The suggestion of arranging manual monitoring and on-line monitoring facilities is put forward to realize the real-time monitoring of dam of tailings pond and flood discharge situation. The research results can provide a technical reference for the design, construction and management of tailings pond.

The Tianjingshan mining area is a limestone quarrying region for construction purposes in the typical arid areas of northwest China. Due to severe environmental damage in this mining area, natural revegetation is no longer possible, and there is an urgent need for restoration and management. In light of this, from the overall perspective of the mine's eco-geological environmental system, research was conducted on the eco-geological environment of the mining area using the analytic hierarchy process (AHP) and fuzzy comprehensive evaluation (FCE) methods. 20 evaluation factors were selected from both ecological and geological aspects. An eco-geological environmental evaluation system was constructed that is consistent with the characteristics of typical arid areas and oriented towards mine ecology restoration. This system aims to quantitatively and accurately determine the quality levels of the eco-geological environment of the mining area and match appropriate restoration and management models for corresponding levels. Based on the evaluation result that the eco-geological environment quality level of this mining area was poor (Level Ⅲ), targeted restoration and management mode of the mining area were carried out using combined methods of geological disaster risk elimination, soil reconstruction, vegetation reconstruction, and manual maintenance. Secondary revegetation of the mine relic site was ultimately achieved. The results show that the evaluation system can provide a relatively objective evaluation of the eco-geological environment of limestone mines in arid areas and the proposed restoration and management modes have good restoration and management effects, which can be replicated and promoted for application in local and similar arid and semi-arid areas for the restoration and management of mine relic sites.

Mining activities will cause contamination to the mining area and the surrounding soil. Reasonable layout of sampling points is very important for mastering the soil environmental conditions and using remote sensing to invert the spatial pattern of soil contamination. Taking an iron mine area in Luanzhou and the surrounding area affected by mining activities as the sampling area, according to the principle of zoning control, the study area was divided into mining activities directly affected area and mining activities indirectly affected area. The classical statistical analysis method was used to calculate the reasonable sampling number and layout the sampling grid. Based on landscape diversity index and weighted average method, the layout scheme of soil heavy metal monitoring sampling points was designed. The results show that 215 sampling points are calculated by reasonable sampling number in different precision partitions. Among them, 34 grids are selected by landscape diversity index in mining activities directly affected area, and a total of 196 sampling points are allocated. The mining activities indirectly affected area uses the weighted average method to allocate 19 sampling points through the area of land-use type. After different precision, different methods to determine the distribution of forest land sampling number 39, farmland sampling number 95, bare land sampling number 20, river beach sampling number 16, tailings and mining area stope sampling number 45. The sampling scheme is based on remote sensing images, combined with the geographical location of the study area and the distribution characteristics of land-use types, taking into account the actual situation of sampling costs, which helps to reduce the sampling workload. There may be uncertain factors such as mining activities, topography and hydrology in the actual sampling work, so the sampling scheme needs to be adjusted in combination with the on-site situation.

Due to factors such as high pressure, water depth, and complex geological formations, the difficulty and complexity of ocean exploration are much higher than those on land, which puts high demands on the quality and performance of drill bits, and even requires customized production according to special needs. In order to provide customized drill bits in time, 3D printing technology has been innovatively applied to the production process of ocean exploration drill bits. Using spherical tungsten carbide (WC), cobalt (Co) powder, and diamond particles as raw materials, a method of selective laser melting (SLM) printing the working layer of drill bits has been proposed. By testing the density and hardness of printed samples, the printing parameters were optimized. The results show that the bulk density of printed WC-20Co-diamond stone can reach up to 13.45 g/cm³, and the hardness can reach 1 455 HV. Under the conditions of laser power of 220 W and scanning speed of 400 mm/s, high-quality molding can be achieved. The final prepared tungsten carbide cobalt based diamond drill bit sample has a good bonding between the hard alloy and the steel matrix interface. The production mode of drill bits based on 3D printing can significantly shorten the manufacturing time, produce drill bits that are suitable for various extreme environments and complex rock formations on the seabed, and timely meet the needs of printing drill bits on ocean drilling ships.

In order to improve the accuracy of slope stability prediction, a slope stability prediction model based on multi strategy improved cuckoo search algorithm (ICS) optimized Elman neural network was proposed. Firstly, the population was initialized using Sinusoidal chaos, and strategies such as dynamic step size control and 1% step discretization of discovery probability were introduced to improve the slow convergence speed and poor accuracy of the cuckoo search algorithm. Simulation results on 7 benchmark functions show that compared with the CS algorithm, the optimization ability and convergence speed of the ICS algorithm are significantly improved. Then, the ICS algorithm was used to optimize the weights and thresholds of the Elman neural network, and the optimal slope stability prediction model was constructed. The results show that the relative error range of the ICS-Elman model for predicting the safety factor of slope stability is –2.81%−6.98%, with root mean square error and mean absolute error of 0.275 0 and 0.342 2, respectively. Compared with the Elman and CS-Elman models, the ICS-Elman model has better stability and accuracy. Compared with the CPSO-BP neural network, the ICS-Elman neural network has a relative error range of –1.57%−1.25% in predicting values, indicating better prediction accuracy.

In mine production, the roof fall accident of working face is directly related to the hydraulic support. According to this theory, a prediction model based on multi-source data fusion was proposed to predict the load of hydraulic support. By studying the theory of pressure deformation characteristics of coal seam roof, the composition and working principle of hydraulic support, the bearing theory and the influence of working condition on hydraulic support, the influencing factors of load change were analyzed, and the data of key stress components were collected. The K-means clustering algorithm was used to cluster the characteristics of the data, and the load was classified and predicted. The whale optimization algorithm (WOA) was used to optimize the long short-term memory network (LSTM) and the deep belief neural network (DBN) respectively, and the WOA-LSTM series prediction model and the WOA-DBN series prediction model were established. The results are as follows. Firstly, the mean absolute error is reduced by 0.228 7, 0.206 4 and 0.067 7 respectively in the prediction of the front column load of 20^# hydraulic support by WOA-DBN model. The root mean square error is reduced by 0.212 9, 0.195 3 and 0.072 5, respectively. Secondly, in the prediction of the rear column load of 20^# hydraulic support by WOA-DBN model, the mean absolute error is reduced by 0.303 1, 0.244 6 and 0.205 4 respectively. The root mean square error is reduced by 0.291 9, 0.246 4 and 0.238 9, respectively. It can be seen that the WOA-DBN series prediction model is more suitable for load prediction and has higher accuracy.

The SICOMINES copper and cobalt ore in the Democratic Republic of Congo has a Cu content of 2.47% and a Co content of 0.237%, belonging to high oxidation rate and complex mineral composition ores. In response to the high cost of single flotation beneficiation and low recovery rate of copper and cobalt, combined with the properties of the ore, a flotation-magnetic separation combined process was used for beneficiation experimental research. By conducting experiments on the types and dosages of collectors and vulcanizing agents, the optimal process parameters were determined as follows: the dosage of pentyl xanthate collector is 1 185 g/t, and the dosage of combined vulcanizing agent (sodium sulfide : sodium hydrosulfide = 1:1) is 7 000 g/t. When the grinding particle size of the raw ore is –0.074 mm accounting for 70%, the stepwise sulfurization flotation method is firstly used to recover the easily floatable copper sulfide concentrate, copper oxide concentrate, and cobalt concentrate. Then, the flotation tailings are subjected to strong magnetic separation treatment to recover the copper cobalt magnetic minerals. Finally, the total copper recovery rate is 79.83% and the total cobalt recovery rate is 54.79%, achieving the comprehensive and efficient utilization of high oxidation rate copper cobalt ore resources.

Copper-cobalt ore with high oxidation rate in SICOMINES from the Democratic Republic of the Congo contains some copper-bearing minerals which are difficult to be separated, resulting in poor separation indexes. In order to recover copper-bearing minerals in flotation tailings, the mineral composition of flotation tailings was analyzed. The flotation tailings were re-separated by gravity separation, magnetic separation, flotation and combination of various separation methods. Finally, it was determined that the flotation tailings were separated to one roughing and one scavenging strong magnetic separation, the magnetic separation concentrate was separated by one roughing and one scavenging flotation, and the flotation tailings of the magnetic separation concentrate were separated by a section of strong magnetic separation process. The recovery rates of total copper and total cobalt reach 84.74% and 56.88% respectively after adding the re-separation process on flotation tailings, which are 8.96 and 8.28 percentage points higher than those of the original flotation process. Meanwhile, conducting re-separation on the magnetic separation concentrate from magnetic separation of flotation tailings can greatly reduce the leaching acid consumption of magnetic separation concentrate.

In order to realize the efficient utilization of sodium oleate, which is a collector for iron ore flotation, the effect of ethyl oleate on the reverse flotation separation of quartz from fine hematite was investigated by carrying out quartz pure mineral flotation test, binary mixed mineral flotation test and actual mineral flotation closed-circuit test. The promoting effect mechanism of ethyl oleate on the flotation of quartz by sodium oleate was clarified by infrared spectroscopy, surface tension measurement and contact angle measurement. The results show that in the pure mineral flotation test, when the sodium oleate is 160 mg/L and the pulp pH is 11.0, the maximum recovery of quartz increases from 80.34% to 94.85% after adding 40 mg/L ethyl oleate. In the flotation test of binary mixed minerals of quartz and hematite, compared to the dosage of 160 mg/L sodium oleate, when the dosage of sodium oleate is 120 mg/L and the dosage of ethyl oleate is 40 mg/L, the grade of iron concentrate increases from 62.32% to 65.04%, and the recovery of iron concentrate increases from 89.64% to 93.86%. In the actual mineral flotation closed-circuit test, compared with the flotation index under the single sodium oleate system, the grade and recovery of iron concentrate increase by 3.01 percentage points and 3.52 percentage points respectively after adding ethyl oleate. The promotion effect mechanism of ethyl oleate on the flotation of quartz by sodium oleate is that ethyl oleate and sodium oleate are combined by hydrogen bond, which enhances the adsorption strength of sodium oleate on the surface of quartz, strengthens the adsorption stability of the reagent, and improves the hydrophobicity and floatability of the quartz surface.

Taking a copper-silver polymetallic sulfide ore in Inner Mongolia as the research object, the process mineralogy analysis and flotation tests were carried out. The research results of ore properties show that except for a small amount of chalcopyrite, sphalerite and galena in the raw ore, copper and silver mainly exist in the form of silver tetrahedrite. The flotation tests show that, firstly, the copper-silver mixed flotation process is used to realize the separation of copper-silver minerals and sphalerite. Secondly, the mixed flotation concentrate is reground and floated to realize the separation of copper-silver and galena. Finally, the process flow of copper-silver mixed flotation-regrinding of mixed flotation concentrate-copper-silver flotation concentration is determined. The copper-silver concentrate with copper grade of 18.98%, copper recovery rate of 80.98%, silver grade of 10 521.88 g/t and silver recovery rate of 89.81% is obtained by closed-circuit test. By feeding the flotation tailings into the subsequent lead-zinc separation operation, the efficient comprehensive utilization of copper-silver mineral resources has been realized.

In order to efficiently separate copper ore, a stacked step flow separation model was proposed according to Knelson concentrator based on centrifugal gravity separation technology combined with reverse fluidization and step flow principle, and secondary separation was realized on the basis of centrifugal separation. The distribution of pressure, tangential velocity and axial velocity in the separation flow field of the stacked step flow model was analyzed by Fluent software. The effects of rotational speed and reverse flow velocity on the separation characteristics of copper ore were studied. The results show that the pressure distribution of the flow field increases gradually from the center to the wall surface. However, due to the presence of reverse flow force, the maximum pressure does not fully fit the wall surface. The abrupt change of tangential velocity at the step indicates that there is a vortex, which is conducive to the separation of light particles. The axial velocity as a whole presents an upward flow, which is conducive to the discharge of light particles from the upper outlet after separation. The axial volume concentration distribution of Cu particles shows a decreasing trend from bottom to top, and the radial volume concentration is the highest near the wall surface, while the volume concentration of SiO₂ particles is the highest at the top of the axial direction, and the volume concentration is lower at the radial direction. When the feed speed is 0.5 m/s, rotational speed is 50 r/min, and reverse flow velocity is 0.012 m/s, it can be obtained that the recovery of Cu particles is 87.70%, and enrichment ratio is 13.45. The stacked step flow model has the best effect on the separation of SiO₂ particles and Cu particles. The cloud images of particle volume fraction show that Cu particles are enriched in the concave of the inner wall of the step flow, and SiO₂ particles have a low volume fraction in the concave of the wall due to the separation force of vortex and reverse flow, which more directly shows the separation effect of the stacked step flow model. The research results can provide references for the improvement of centrifugal beneficiation equipment.

In order to accurately predict the supply-demand situation and guarantee degrees for important mineral resources in Liaoning Province during the 14th Five Year Plan period, based on the development and utilization of mineral resources during the 13th Five Year Plan period, the method of demand trend analysis was adopted to track the industrial chain, and the development and utilization data of upstream and downstream production links or consumption data of downstream product end markets were collected. The demand and guarantee capacity of iron ore, coal, gold ore, magnesite, flux limestone, and boron ore during the 14th Five Year Plan period were predicted. The accuracy of the prediction results was verified by the actual yield and consumption of each mineral in 2021 and 2022. The results show that the demand for iron ore ranges from 183.75 million to 191.1 million tons per year, coal from 179.92 million to 191.35 million tons per year, gold ore from 8.11 million to 8.92 million tons per year, magnesite from 30.48 million to 33.81 million tons per year, flux limestone from 14.96 million to 15.4 million tons per year, and boron ore from 4.16 million to 5.39 million tons per year in the next 5 years. The guarantee degree of magnesite and flux limestone is relatively high, which can achieve supply-demand balance. Gold ore requires a large amount of imports, and the guarantee degree of iron ore, coal, and boron ore is insufficient. It is necessary to further strengthen the exploration of deep and peripheral mineral resources and improve mining capacity construction.

Safety and stability is the premise of intelligent mine reform. In order to improve the scientific management level of mine enterprises and reduce the accident rate, based on social information processing theory, self-determination theory and affective event theory, a moderated chain mediation model was constructed with taking charge behavior and harmonious safety passion as mediating variables and organizational resilience as moderating variables. A questionnaire survey was conducted to collect data from 400 miners in a coal mine in Shanxi Province in two stages, with a total of 364 valid questionnaires collected. And the hypothesis model was verified by empirical research method. The results are concluded as follows. Firstly, resonant leadership has a positive effect on miners' proactive accountability behavior. Secondly, resonant leadership positively affected miners' proactive accountability behavior through the independent mediating effect of perceived insider status and harmonious safety passion, as well as the chain mediating effect of perceived insider status and harmonious safety passion. Thirdly, organizational resilience can positively regulate the relationship between harmonious safety passion and proactive accountability behavior, and positively regulate the chain mediation relationship between perceived insider status and harmonious safety passion.