With the high risk of coal and gas outbursts in deep roadway tunneling, gas extraction from the floor rock roadway is an effective way to reduce coal seam gas pressure and protect the safety of coal roadway tunneling. The location of the rock roadway and its effect on the coal roadway is a problem worth studying. In this work, taking the Shoushan No.1 mine as the engineering background, a corresponding discrete element model is established based on the rock stratum. According to the sequence of roadway excavation, the changes in rock stress, rock deformation and the damage distribution are analyzed. Results show the floor rock roadway has a certain unloading effect on the upper coal seam, and this effect is reduced when the distance between the rock roadway and the coal roadway increases. The deformation of floor rock roadway increases significantly after the coal roadway tunneling. The damage of the floor rock roadway is mainly affected by the roadway position, and the soft or thin rock layers are not conducive to roadway stability. The vertical distance between the coal roadway and the rock roadway is finally determined as 12m and the field investigation results show the floor rock roadway and coal roadway have good stability.

Abstract: In response to a series of problems caused by the complexity of auxiliary lifting and transportation systems in the development process of gently inclined coal seam groups, it is proposed to transform the Shajihai No.1 mine into an auxiliary lifting and transportation system with the goal of trackless auxiliary transportation system and the construction of a new gentle slope inclined shaft as the transformation method. Combined with the layout of the shaft, the mine is optimized and designed for development. The coal seam group is developed by using gentle slope inclined shafts as auxiliary transportation for mining areas to reduce the number of mining areas and extend the service life of each mining area, which is conducive to alleviating the tense situation of mining and excavation continuity. The optimization ideas for the development of Shajihai No.1 mine have certain reference significance for the development of coal seams in Xinjiang.

Abstract: Under the dual carbon target, clean heating has become one of the important measures of green mine construction. Based on the heat harm problem caused by the deep mining project of coal resources in China and the consummation of waste heat utilization in the current coal-water-heat co-mining mode, this paper puts forward an integrated system of thermal energy access in deep mine, and analyzes the connotation and technical framework of the system, this paper introduces the cooperative operation process of the system, including the heat extraction system, the ground heat exchange system, the heat storage system and the grouting system. The system drilled a horizontal hole in the surrounding rock of the roadway and arranged heat exchanger to extract the geothermal energy of the surrounding rock, and converted and transported the low-grade geothermal energy mined from the underground through the underground heat pump unit. Part of the thermal energy was used in the ground heating system, and the abundant thermal energy was stored in the thermal storage system to meet the working face cooling demand.The key technologies such as efficient extraction of thermal energy from surrounding rock, heat storage by filling underground space, stability control of integrated system, prevention and control of pollutants and safety guarantee are described, a model of“Co-construction, co-storage and co-sharing” of thermal energy in surface underground space is proposed. The theoretical research system of the deep heat damage treatment and the integration of geothermal exploitation and storage is further clarified. The application of this system in the mine provides a reference for the development and application of deep formation energy storage technology.

The working slope Angle directly affects the stripping amount and production stripping ratio. Increasing the working slope Angle can reduce the advance stripping amount, reduce production stripping ratio, save transportation distance and reduce production cost. However, while improving the working slope Angle, it is necessary to pay attention to the "two quantities" of the open pit to ensure the continuous and stable production of the open pit. This article takes the Hongshaquan open-pit coal mine as the engineering background to study the relationship between the working slope angle and the changes in advance stripping amount and production stripping ratio, and combined with the actual production conditions on site,. the scheme of realizing steep slope mining of working slope is put forward. The results show that when the working slope Angle increases by 2°, the advance stripping amount decreases by 9.67Mm3, and the production stripping ratio decreases by 0.22; When the stripping step is combined in pairs, the working slope Angle is increased to 12°, the production stripping ratio can reduce to 2.7, and the "two quantities" of the open pit will be guaranteed.

Quantitative prediction of the concentration and influence range for unorganized particulate matter generated by aerodynamic disturbances and mechanical disturbances during the development of open-pit coal mines in the Gobi area is the key point and difficulty on the atmospheric environmental impact assessment. Taking the Hongshaliang open-pit mine as the research object, based on the technical guideline for Compilation of Dust Source Particulate Emission Inventory (Trial) and ADMS-EIA software, an evaluation strategy of meteorological data preprocessing-unorganized source intensity accounting-model quantitative prediction was established. The grid concentrations of TSP, PM10 and PM2.5 under dust control measures were visualized by contour plot. Research shows that unorganized particulate matter from open-pit coal mine development is mainly concentrated within 1000 m of the disturbed working face. Compared with regular watering dust control measures, the use of chemical covering agents can reduce the concentration contribution of TSP, PM10 and PM2.5 at 500 m downwind of the dominant wind 56%, 56%, and 41%, respectively. Quantitative prediction of unorganized dust sources for open-pit mine in Gobi region can provide support for determining the atmospheric environment protection distance and assessing the feasibility of pollution control measures.

Silos are widely used facilities in coal preparation plants and other material handling units, but the complex spatial configuration at the bottom of silos presents challenges for accurate calculation of concrete infill volume. This paper thoroughly investigates two distinct calculation methods: Firstly, a parameterized Excel-based approach is introduced, combining space segmentation technology, where the complex area is divided into n manageable sectors of arc-shaped surfaces. The total infill volume is approximated by accumulating the volumes of these segmented regions, referred to as the segmentation method. Secondly, employing principles of calculus, an analytical computation method is developed to determine the exact volume of the three-dimensional geometric body between the silo’s inner wall and the square opening, thus generating a more precise mathematical model. Through comparative analysis of these two methods and validation against actual measurements, it is found that the segmentation method offers the advantage of intuitive comprehension and expedient estimation, with an error margin of -0.90%. Conversely, the calculus method delivers higher theoretical precision and is suitable for accurate calculations in complex geometries, achieving an error rate as low as 0.46%. The research aims to optimize the calculation method of concrete filling quantity quantity in the silo of coal preparation plant, improve the calculation accuracy, and provide accurate reference basis for the subsequent design and construction of similar projects. [1-9]

In order to study the grouting modification and surrounding rock control technology behind the water rich and sandy layer of a large cross-section inclined shaft, taking the main inclined shaft of Caojiatan Coal Mine as the background, numerical simulation was used to compare and analyze the water inrush and surrounding rock control effects of the sandy layer without grouting and using ordinary Portland cement, cement water glass, and SJP grouting materials for grouting. A reasonable control plan for the surrounding rock of the sand rich layer was proposed. The research results indicate that the deformation, plastic zone range, and permeability of the surrounding rock of the tunnel after grouting are significantly reduced. The surrounding rock control and anti-seepage ability of SJP grouting material are better than those of ordinary Portland cement and cement water glass grouting material. The on-site engineering application shows that after using SJP grouting modification, the water inflow in the sand layer section of the inclined shaft is reduced from 97m3/h to 8m3/h, with a reduction rate of 92%. The overall stress state of the treated section of the wellbore structure is good, and the wellbore structure is basically stable. The use of SJP grouting material for wall grouting effectively ensures the safety and stability of the inclined shaft.

Abstract: It is of great significance to show the mine pressure of the roadway, the stability support of the roadway and the improvement of coal utilization rate along the empty alley, and it is aimed at Hecaogou No. 2 Coal Mine 1105 The mine pressure of the roadway with the return air of the working face showed abnormalities and the difficulty of support, so it was decided to adopt the technical scheme along the empty alley, combined with the actual situation of the mine. The research results show that the vertical stress of the roadway roof decreases significantly after cutting the top and leaving the alley, the stress change of the roof plate shows a unimodal distribution during the mining process of the working face, the influence range of the advanced support stress of the working face is greater than 6 0m, and the influence range of the lateral support stress of the working face is about 6 0m, when the working face is mined back to 9 At 0m, the vertical stress change of the roadway roof reaches the maximum. According to the results of mine pressure monitoring, after the top blasting of the thin coal seam, the force of the constant anchor cable was significantly reduced, and the effect of the roadway was good, while the deformation of the constant anchor cable and the surrounding rock of the roadway showed a trend of "stability-fast-slow-stable". The maximum deformation position of the top and bottom plate of the roadway is the middle of the roadway, and the roof plate reaches a stable state after 1 10m of mining of the working face, and the bottom plate reaches a stable state after 8 0m of mining of the working face.

In order to realize the long distance precise drilling and detection under the shaft and make up for the shortcomings of ordinary drilling rigs, such as low detection accuracy, short detection distance and inability to flexibly adjust the drilling trajectory, Shendong Mining Area generally uses long distance directional drilling rigs for drilling. At present, in Shendong mining area, long distance directional drilling rig has been widely used in advance detection after exploration in heading face, remote drainage of water accumulated in overlying goaf and accurate detection of some geological structures. During the construction of long distance directional drilling, in order to achieve the purpose of detection, it is necessary to scientifically determine the reasonable detection track in the horizontal and vertical directions before construction, and flexibly adjust the drilling direction according to the detection requirements; Before construction, relevant projects and facilities required for drilling rig construction shall be prepared in advance. After the exploration is completed, the criteria for judging various detection results shall be studied and determined. This paper introduces a series of techniques for long distance directional drilling rig exploration construction.

The form of coal mine rockburst disasters is severe, and local pressure relief measures are difficult to effectively eliminate the problem of rockburst disasters. The prevention and control of rockburst are often in a passive state. In response to the difficult problem of preventing and controlling rockburst on the top plate of the working face, the principle of inducing rockburst on thick and hard roof is analyzed. The technology of preventing and controlling rockburst at the source of the roof force source structure in surface hydraulic fracturing transformation is proposed, and experiments are conducted on the 4107 working face of Wenjiapo Mine. The results show that the thick and hard roof provides static load increment without collapse, sudden fracture provides dynamic load disturbance, and the superposition of dynamic and static loads breaks through the critical load to induce impact initiation. Ground hydraulic fracturing causes cracks in the thick and hard roof, artificially liberating layers, reducing the strength and integrity of the thick and hard roof. Long beams become short beams, and large blocks become small pieces. The surface hydraulic fracturing technology causes the roof to crack, changing the overlying load from hard transmission to soft transmission, reducing the stress concentration level of the surrounding rock of the roadway, and ensuring the smooth recovery of the working face.

To address the directional requirements of underground engineering shafts, the quadrilateral connection method is used to achieve shaft orientation, and the influence of quadrilateral shape on directional accuracy is studied. Determine a symmetrical quadrilateral using one angle and one edge, and evaluate the accuracy of the network using indirect adjustment. Calculate the accuracy of directional edges by writing a program to traverse conditional angles and edges, draw contour lines, and analyze the optimal shape of the quadrilateral connection method. This study can be applied to underground engineering shaft orientation.

To determine the key technical parameters for cutting and roof retention in medium-thick coal seams with hard roof conditions, this study takes the transport roadway of the 1026 working face in the Jiegou Coal Mine in Suzhou, Anhui, as the engineering context. A mechanical model for cutting and roof retention in hard roof conditions is established. Through theoretical analysis, numerical simulation, and on-site experiments, the study elucidates the influence patterns of cutting height, cutting angle, and borehole spacing on the cutting and roof retention effects. Key technical parameters for cutting and roof retention in the transport roadway of the 1026 working face are defined as follows: a cutting height of 10m, a cutting angle of 0°, and a borehole spacing of 0.5m. Field measurements demonstrate that the cumulative roof subsidence in the retained section of the transport roadway ranges from 170mm to 250mm. The hydraulic supports on both the goaf side and the solid coal side remain stable for a distance of 180-200m behind the advancing face, and the anchor bolts exhibit sufficient anchoring force, resulting in a satisfactory cutting and roof retention effect. The findings of this study can provide valuable reference for determining key technical parameters for cutting and roof retention in mines with similar geological conditions.

In order to solve the problem of controlling the surrounding rock of the gangue gangue in the fully mechanized mining face with large mining height. Taking field experiments and theoretical analysis as the main means, two types of gangue gangue support schemes, totaling 4 groups, were designed, and the deformation laws of gangue gangway under different roof support resistance conditions and different gangue gangue resistance conditions were discussed, and established. The displacement of the gangue gang under different gangue support conditions changes to the mechanical formula. The results show that: (1) the deformation value of gangue gangue and the deformation value of coal gangway in the roof-cutting entry retaining area supported by unit supports are both smaller than those in the roof-cutting entry retaining area supported by single pillar and roof beam; (2) The root cause of U-shaped steel slip is that The tensile stress or compressive stress is greater than the critical friction force of the overlapping part of the U-shaped steel; ③ The greater the rigidity of the U-shaped steel for the gangue gang support, the smaller the bending deflection of the gangue gang; Good blocking effect. This study can provide a reference for the support of gangue gangue under the same conditions.

With the increasing depth of coal mining in China, the water pressure of Ordovician limestone aquifer on the floor of coal mining face is also increasing. When hidden collapse column is developed on the floor of mining face, the effective water barrier layer is not enough to withstand the water pressure of high confined aquifer, which often causes water inrush in mine. In view of the difficult technical problem of the formation of high water pressure water plug on the floor, this paper takes the Ordovician ash water inrush disaster control project of 3315 working face of Gucheng Coal Mine as an example. The paper puts forward the treatment method of double-layer directional horizontal holes on the ground. The upper holes are used to slow down and reduce the high pressure moving water, and the lower holes are used to quickly intercept the moving water channel. According to the engineering practice, the principle of hole distribution, aggregate filling method, grouting method and grouting end standard for double-layer water inrush treatment of high pressure water inrush are studied. At the same time, the key technology of double-layer water inrush disaster treatment is formed. The results show that the double-layer directional hole has obvious effect on rapid exploration of water inrush channel and construction of water plug, and the water plug rate is 100%.

Based on the "rich coal, poor oil, little gas" resource endowment conditions in China, coal is still the cornerstone of energy security. Abundant mine water generated by coal mining is a precious water resource, which can be used for mining area production and life by effective treatment. Accurate prediction of mine inflow is significant in mine drainage design and water resource proof. Taking Baorixile Surface Mine as an example, the hydrogeology and water filling conditions of the mine area are analyzed, and the mine inflow under the production condition in the future (2025) is predicted by using the hydrologic analogy method. Based on the relevant datas of the mine from 2001 to 2019, the multiple regression equation of the mine inflow and other related factors is established.The results show that the hydrologic analogy method has high prediction accuracy and is feasible. Finally, the predicted miner inflow value of Baorixile Surface Mine under the future production condition is 6375.02m3/d.The study provides reliable data support and technical support for safety production, drainage design and optimal allocation of water resources in mining areas.

Coal occupies a decisive position in the process of China's economic construction. With the increasing mining depth of coal mines, the high temperature heat damage of deep mines has become a major factor restricting coal mining. Local cooling, as a supplement to centralized cooling, can effectively eliminate the high temperature heat damage of deep mines. In view of the problem of high temperature heat damage in the high-temperature excavation face of a coal mine, this paper focuses on the design scheme and practical application effect of the project composed of closed-type exhaust air cooling tower, multi-stage serial direct expansion combined cabinet, explosion-proof semi-hermetic screw compressor with large pressure ratio and so on. The results show that the closed-type exhaust air cooling tower scheme can improve the comprehensive energy efficiency level of the mine, the new mine local cooling system can be applied to the working conditions of high-pressure ratio mines, and the operating condensation temperature can reach up to 80°C, and the direct expansion combined cabinet adopts multi-stage serial direct expansion combined cabinet to achieve a temperature drop of 10°C and a relative humidity drop of 30%.

The underground water supply network system of coal mine is the key link to ensure the safety of coal mine production. Aiming at the problems of high energy consumption, high leakage rate and increased regulation complexity of the underground water supply network system of coal mine in Shaanxi province, the intelligent regulation and control policy research is carried out based on the actual working conditions of the underground water supply system. A two-level optimal scheduling model is established based on the factors affecting the pipeline network. The optimal water supply pressure and water supply of each pump house are determined through the first-level optimal scheduling. Then, the operation cost of the pump group is taken as the objective function to establish the second-level optimization model to seek the optimal operation scheme of the pump. In order to solve the problem that the traditional genetic algorithm is easy to fall into the local optimal solution, the combined mutation operator is used to improve the model. The experimental results show that the energy consumption of the underground coal mine water supply system is significantly reduced and the energy saving effect is remarkable, and the average daily energy saving is 8.8% under the premise of ensuring the safe operation of the water supply system.

In order to realize the real-time monitoring, measurement, analysis and comprehensive evaluation of the power quality of underground electrical equipment in coal mine,this paper proposed an explosion-proof underground power quality monitoring system based on current and voltage sensing system,developed the isolated current/voltage sensing unit, high-precision ADC unit and system control hardware system, carried out the electrical explosion-proof design, and constructed the on-line monitoring platform of mining power quality.According to tested to underground 6 kV mining mobile substation, this monitoring system can realize the effective on-line monitoring of harmonic voltage, current and power , and generate monitoring data statistical graphics and statistical curves,accurately reflect the operation level of coal mine underground power grid and provide basis for managers' investment decision-making.

Abstract:In response to the complex factors such as residual coal pillar pressure and goaf water accumulation in the overlying 4-coal goaf during the initial mining period of Guojiawan Coal Mine in Guoneng Yulin Company, the pressure step distance and stress distribution of the 51208 fully mechanized mining face were studied through theoretical calculations, FLAC3D numerical simulation, and other methods; By adopting engineering methods such as geophysical exploration and drilling in advance, identify and release accumulated water in the overlying goaf that affects safety production; Finally, through the safety mining practice of the 51208 fully mechanized mining face and the summary of the mining pressure laws such as the initial mining and periodic pressure of the 51208 fully mechanized mining face, it was found that the initial pressure and periodic pressure step distances of the 51208 fully mechanized mining face were 70m and 10m, respectively. This effectively verified the necessity of theoretical calculation, numerical simulation, advance geophysical exploration, drilling and other engineering methods, as well as the rationality of safety technical measures. The main hidden disaster causing factors affecting the pre mining pressure of the 51208 fully mechanized mining face, goaf water accumulation, coal seam outcrop and gap development were successfully controlled; We have accumulated valuable experience that can be learned from for the next step of safe mining of similar fully mechanized mining areas, which has certain promotional significance for the region.

Different arrangements of working faces can result in different surface subsidence patterns. The negative coal pillar mining method has been widely used in China, but the surface subsidence patterns and mechanisms under this arrangement have not been thoroughly studied. Therefore, this paper investigates the influence of the spatiotemporal relationship of negative coal pillar working faces on the subsidence of the inclined main section through field measurements, physical modeling, and numerical simulation. The results show that the subsidence curve of the negative coal pillar working face is smoother on the triangular coal pillar side than on the rectangular coal pillar side, with an increase in subsidence of the overlying strata and connection of the collapse zones, resulting in a flat-bottomed subsidence area on the surface. As the mining time interval increases, the surface deformation becomes more uneven, and the disturbance of the continuous working face on the overall strata decreases, concentrating the deformation above the initial mining face. The point of maximum subsidence shifts towards the direction of the initial mining face, and the maximum subsidence initially decreases and then stabilizes. Based on the probability integral method, this paper proposes a corresponding method for predicting surface subsidence, which is validated by comparing with field measurements data, demonstrating its practicality and reliability.

In order to adapt to the increasing development trend of locomotive distance and load under operating conditions, and to improve the operational stability of locomotive traction under sudden loads, this article proposes a dual power supply system and its droop control method for locomotive traction power supply under operating conditions. In response to the special characteristics of industrial and mining traction, such as sudden load changes and large differences in round-trip loads, a comparative analysis was conducted on the applicability of precise and imprecise current sharing strategies between stations for industrial and mining locomotive traction. Based on the analysis results, a dual power supply system for industrial and mining locomotives and a coordinated droop control strategy between stations were proposed. On this basis, a current feed-forward control strategy was introduced, and a simulation model and a low-voltage test traction physical model platform for industrial and mining locomotives including traction substations were built. The test results showed that the voltage stability of the locomotive under sudden load changes was significantly better than that of conventional droop control methods. This study provides strong solutions and technical support for the development of locomotive traction towards high capacity, long-distance, and high reliability.

In this paper, the problems with the protection and control of underground mining power distribution devices, which exist in the same source of power supply and power supply system were analyzed, a method of independent power supply for mining were proposed, the power supply mode for protection and control of mine power distribution device, mine lithium-ion battery power supply,mine PT protection box and its power switching device were researched and designed, the independent power supply of protection and control power supply, one for use and one for standby were realized, the safe operation of the power supply system were ensured.

For the difficulties in identifying and locating surface defects on mining conveyor belt, a mining Conveyor Belt Defect Detection System is designed based on maximizing reliable region through decision-level fusion. Firstly, the YOLOv4 and SSD models are trained using public datasets with the transfer learning, and the decision-level fusion method is proposed for defect detection results based on its predicted score and overlapping situation. At the decision level, the two models are fused to maximize reliable regions, which can achieve defect identification and localization of conveyor belt. The effectiveness and reliability of the proposed method are validated and analyzed through public datasets and mining conveyor belt defect datasets. The results illustrated that the proposed method can fully utilize the detection results of YOLOv4 and SSD models to achieve high accuracy, recall, and overlap rates. It can achieve the accuracy rate and overlap rate of over 85% and 0.6, respectively. The defect detection system is beneficial for defect detection and maintenance of mining conveyor belt, and it is significate for safe and reliable operation of the mining conveyor.

Gas drainage by borehole is one of the most economical and effective methods for comprehensive utilization and disaster prevention of coal seam gas. To study the evolution mechanism of the main controlling factors in the process of coal seam gas extraction, a multi-field coupling model for gas migration was established and solved using COMSOL Multiphysics software. The results indicate that due to the influence of coal pore and fracture network structure, there is asynchrony between the changes in matrix gas pressure and fracture gas pressure, making it difficult for gas to migrate from the matrix. The fracture system and matrix system jointly control the gas migration ability of the coal body. In the early stage of gas extraction, the gas migration process is mainly controlled by the fracture system. At this time, increasing the permeability of the coal seam can effectively improve the gas extraction efficiency; As the gas extraction progresses, the gas migration process gradually shifts to the control of the matrix system. At this time, simply increasing the permeability of the coal body is difficult to effectively improve the gas extraction efficiency. Measures should be taken to improve the diffusion performance of the coal matrix.

The accuracy of prediction of water inflow of shaft is of much importance for the safety and high effective of shaft boring. “Large well method” is often used previously to predicate the water inflow of shaft, of which the result is of much difference with the reality. The reason is that the theoretical basis of “large well method” lies in Dupuit formula which requires a constant hydraulic head as boundary conditions and a steady flow as the flow pattern. However, many aquifers in coal-bearing strata can’t meet the requirement of Dupuit formula. A case study of the vertical air-return shaft in Huanghaojie coal mine was taken, method of transient water inflow from partially penetrating well in confined aquifer was adopted to predicate water inflow of shaft after a comprehensive comparative analysis of the practical hydrological conditions of shaft, which is of large diameter, poor recharge condition and partially penetrating. The prediction results show that the water inflow is big at initial stage, which is 131.98 m3/h，and declines approximately 61% rapidly, which is 51.66 m3/h one day later, then decreases slowly, and finally tends to be stable. The prediction value is close to the quantity of drainage water from the dewatering well during the last few months. This study provides references for the water inflow prediction of vertical shaft or coal mine pit in similar hydrological conditions.

Based on the intelligent construction of Qinglongsi coal preparation plant, and in response to the difficulty of centralized management of numerous intelligent control and management systems generated by intelligent construction, a 3-dimensional visualization twin system is studied and constructed to solve the problem. Firstly, 3-dimensional technology is used to construct a 3D scene, create equipment simulation and coal flow simulation. Secondly, based on the Unity3D engine, 3D twin development is carried out, combining process data with time as a variable and 3D models with space as a variable. This achieves full integration of intelligent systems and physical environments, multi business collaboration and linkage, comprehensive scheduling and early warning, and helps the efficient production and management of coal washing plants.

The 4# fine coal from LongQuan Coal Preparation Plant is characterized with high content of fine slime and intermediate density materials, and poor separation accuracy accordingly. This study is directed on the flotation regularity of 4# coal slime by employing typical non-polar and polar collectors, and a lot of experiments were conducted. Based on these experiments, the kerosene and the amyl benzoate were selected for compounding in different ratios. The effect of compound agents in different ratios on the flotation selectivity of 4# difficult-to-float coking coal and its mechanism were investigated. Experimental results indicate that compared with kerosene as collector alone, the compound collector of kerosene and amyl benzoate (70:30) can increase the concentrate yield by 24.72% under similar concentrate ash content conditions. Compared with using amyl benzoate as collector alone, the flotation collection performance is equivalent, the flotation accuracy is better, and a 30% reduction in reagent cost. Research on the mechanism shows that the contact angle decreases in the order of kerosene - amyl benzoate compound agents > amyl benzoate > kerosene, suggesting that compound agents can better improve the hydrophobicity of the coal sample. Molecular dynamics simulations reveal that the energy gap between the simplified coal model and amyl benzoate molecule is smaller than that between the simplified coal model and dodecane molecule (kerosene) . The adsorption energy calculated by quantum chemistry follows the order of kerosene - amyl benzoate compound agents > amyl benzoate > kerosene. This demonstrates that amyl benzoate itself is easy to adsorb on the coal surface. The 70% kerosene -30% amyl benzoate compound collector exhibits high adsorption firmness onto the coal surface, and the two components can synergistically increase the hydrophobic area of the coal surface, enhance flotation efficiency, and simultaneously reduce the cost of reagents for the coal.

The vibration noise generated by the rollers of the belt conveyor is influenced by various factors. To address the issue of excessive vibration noise, this paper proposes a method that utilizes the finite element-boundary element theory for analyzing and optimizing the vibration noise of the rollers. Firstly, modal analysis and dynamic simulation of the belt conveyor are carried out to explore the vibration characteristics of the rollers; then,the harmonic response analysis of the acoustic field is conducted using the finite element-boundary element composite acoustic field simulation method,this analysis calculates the distribution of the acoustic field in the roller group,and an actual test platform is constructed to validate the reliability of the acoustic simulation model; finally, by considering the conveying capacity and lightweight constraints, the optimal solution for the structural parameters of the roller group and the working parameters of the roller is determined.The optimal solution of the structural parameters of the roller group and the working parameters of the roller are obtained with the constraints of conveying capacity and light weight. The results show that the finite element-boundary element method can effectively simulate the sound field distribution and change rule of the roller group, the optimised noise sound pressure level of the roller group is reduced by about 6.1dB compared with the pre-optimisation, and the comprehensive performance of the roller group has been improved, which can be used to play an effective role in guiding the optimal design of the belt conveyor in the actual project.