Mine Safety Production Research Articles

Discussion on the Application of Mechanical and Electrical Technology Management in Coal Mine Safety Production

Discussion on the Application of Mechanical and Electrical Technology Management in Coal Mine Safety Production

Risk assessment of coal mine safety production management activities based on FMEA-BN

At present, the situation of coal mine safety production is still grim. The key to solve the problem is to analyze the risk of management activities in the process of coal mine safety production. This paper takes the management activities in the process of coal mine safety production as the research object. Firstly, according to the coal mine safety production standardization management system, the safety production management activities are carried out layer by layer. Then, the Failure Mode and Effect Analysis (FMEA) is used to identify the human errors that lead to the failure of management activities at all levels of coal mine. Furthermore, the Fuzzy Set Theory is used to determine the evaluation results of experts on the risk level of coal mine safety production management activities. Combined with Bayesian network (BN), the risk assessment model of coal mine safety production management activities is established. Through the model, the risk probability of coal mine enterprise management activities is accurately calculated. According to the evaluation results, the risk of management activities in coal mine safety production is analyzed.

Risk assessment of coal mine water inrush based on PCA-DBN

To provide an effective risk assessment of water inrush for coal mine safety production, a BP neural network prediction method for water inrush based on principal component analysis and deep confidence network optimization was proposed. Because deep belief network (DBN) is disadvantaged by a long training time when establishing a high-dimensional data classification model, the principal component analysis (PCA) method is used to reduce the dimensionality of many factors affecting the water inrush of the coal seam floor, thus reducing the number of variables of the research object, redundancy and the difficulty of feature extraction and shortening the training time of the model. Then, a DBN network was used to extract secondary features from the processed nonlinear data, and a more abstract high-level representation was formed by combining low-level features to find the expression of the nonlinear relationship between the characteristics of water in bursts. Finally, a prediction model was established to predict the water inrush in coal mines. The superiority of this method was verified by comparing the prediction of the actual working face with the actual situation in typical mining areas of North China. The prediction accuracy of coal mine water inrush obtained by this algorithm is 94%, while the prediction accuracy of traditional BP algorithm is 70%, and the prediction accuracy of SVM algorithm is 88%.

Dynamic Monitoring of Mining Destruction on Coal Seam Floor With Constrained Time-Lapse Resistivity Imaging Inversion

With the increase in coal mining depth, water hazards in deep, strong karst aquifers have seriously threatened the safety of coal mine production. Dynamic monitoring of floor damage during coal seam mining under complex conditions is of great significance for the prediction of water inrush at the working face and for improving coal mining methods. Based on parallel electrical monitoring technology, a constrained time-lapse resistivity inversion method was adopted to process the electrical data of the working face floor. The background resistivity inversion results were used as an a priori model to act on the inversion of subsequent monitoring resistivity data, and the subsequent inversion results of resistivity were fed back to the prior model, which greatly eliminated inversion artifacts. Finally, the dynamic change process of the resistivity profile before and after the failure of the bottom floor of the mining face was determined, and the maximum depth of the failure zone of the floor is 25m, which is located above the lower aquifer. The field monitoring data show that compared with the method of directly comparing the differences between consecutive monitoring images, the inversion profiles obtained by the constrained time-lapse resistivity inversion method have clearer differences in the spatial and temporal dimensions. The depth of the water-conducting damage zone of the floor was clarified, and the basic development characteristic of the floor damage zone of the working face was obtained, which has practical application value for ensuring the safe mining of the working face.

Prevention and Control of Spontaneous Combustion of Residual Coals in Acid‐Soaked Goaf in Gas Drainage Condition

With the increase of mine mining intensity, the scope of goaf continues to expand, a large amount of coal remains in goaf, and the spontaneous combustion fire of coal is particularly serious. In addition, the spontaneous combustion of coal under the condition of gas mining is not clear. At once, spontaneous combustion can induce gas explosion, resulting in the waste of manpower and material resources, bringing hidden dangers to the mine safety production. In order to prevent and control the fire caused by spontaneous combustion of left coal under the condition of gas mining, in this paper by means of laboratory test, field measurement, and numerical simulation, the law of spontaneous combustion of residual coal under gas mining is studied. The index gas of coal spontaneous combustion was determined by temperature‐programmed experimental device. Secondly, the distribution of the stope working face, goaf, and O2 is discussed. It is of great significance to study the spontaneous combustion rule of three belts in goaf under acid leaching condition and then to discuss the best position of injection idling opening and put forward targeted precontrol measures, which is of great significance to guarantee the safety of mine production. The results show that CO begins to appear when the temperature rises to 40 °C, and its concentration increases exponentially with the increase of coal temperature, which can reflect the degree of coal oxidation in goaf. Therefore, CO should be selected as the indicator gas in the working face. Under the influence of negative drainage pressure, the dangerous area will be enlarged. The optimal drainage volume of high drainage roadway is 90 m3/min, and the optimal air intake volume of working face is 1400 m3/min. The area 0–34 m away from the working face is scattered zone, 34–135 m away is spontaneous combustion zone, and 135 m away is asphyxiation zone. When the position of the idler is 50 m behind the working face, the reduction of the oxidation zone is the largest.

Study on Evolution Law and the Mechanical Mechanism of Strong Mine Tremors in a Deep Coal Mine

Strong mine tremor occurs frequently in deep mines, which have brought great hidden dangers to the safety of mine production. This paper takes panel 63/06 in No. 6 mining area of Dongtan coal mine as the research background, through geological survey, laboratory test, theoretical analysis, numerical simulation, on‐site microseismic monitoring, the seismic evolution law and its mechanical mechanism, etc., and the conclusions are as follows: (1) there are three sets of key layer groups between the surface of the panel 63/06 and the coal seam, among which there is a large amount of energy in the thick Jurassic red layer and the lower key layer, which provides an energy basis for the red‐bed to break and generate strong mine tremors; (2) on the plane, most of the strong tremors occurred in front of the mining position of the working face and tended to transfer to the side of the gob, and longitudinal, high‐energy mine tremors are mainly distributed in high‐level red sandstone; (3) the release location of high‐energy mining earthquakes does not match the location of microseismic accumulation, indicating that there is no elastic energy accumulation in the lower surrounding rock before the strong mining earthquake occurs, and it highlights the characteristics of structural occlusal instability rather than energy abrupt instability in the rupture of the red and thick sandstone; and (4) the Dongtan red‐bed type strong mine tremors have a large focal rupture radius, a long rupture duration, a small corner frequency, and a weak initial P wave, and the characteristics of low stress drop and no catastrophic nature indicate that the thick and low‐strength red‐bed is prone to large‐scale fractures, which should belong to the structural instability type mine shock dominated by tensile fracture.

Key Technology of Ground Grouting Treatment for Inclined Shaft under Condition of Super Thick Water-Rich Loose Layer

Shaft is one of the important links of mine production. In recent years, wellbore deviation has occurred many times in various regions of China, especially under the condition of thick water-rich loose layer, wellbore deviation has become an important factor that seriously affects the safety of mine production and miners’ life. Taking the serious deviation of shaft in Guotun Coal Mine in Shandong Province as an example, this paper analyzes the causes of wellbore deviation from the aspects of wellbore geological conditions and wellbore construction methods, and grouting treatment engineering carried out on the deviated shaft under the condition of mine production. Through on-site grouting construction, repair and treatment are remarkable, which provides reference for the subsequent surface grouting treatment engineering of wellbore deviation.

An Optimized Multisource Bilinear Convolutional Neural Network Model for Flame Image Identification of Coal Mine

Underground fire monitoring is an important tool to improve coal mine production safety. In this paper, a multi-source information identification method based on bilinear convolutional neural network (B-CNN) is proposed, which consists of construction of multi-source image acquisition system, B-CNN and integrated decision making based on multi-source B-CNN. Aiming at the problem that Softmax loss function based on the gradient descent in B-CNN is easy falling into the local optimum, an improved Grasshopper Optimization Algorithm (GOA) is proposed to optimally selected two parameters of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {W}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {\theta } $ </tex-math></inline-formula> ; the method of initial solution generation based on sine mapping and the method of accepting bad solution with certain probability are respectively adopted. In order to solve high computational complexity in the stage of model training and integrated recognition by multi-source B-CNN, an image feature preprocessing method is proposed in this paper. Several feature vectors of color feature, shape feature and texture feature of the collected image are extracted and used as input vectors of B-CNN to complete model training and integrated recognition. In simulation experiments, firstly, four Benchmark functions are used to verify the performance of the improved GOA; then, by scaling, expanding and rotating the image to simulate the results of image acquisition at multiple positions and angles, different information sources can be formed to complete the integrated recognition by B-CNN. Three performance indexes of Accuracy, Precision and Recall are used to evaluate the simulation result of different comparative models, which show that the proposed method has better recognition effects.

Research on Drilling and Sealing Technology for Cross Bedding of Superthick Coal Seam

Gas disasters have been affecting coal mine safety production. With the gradual deepening of coal resources development, whether gas extraction meets the standard is particularly important. In view of the low extraction efficiency, through theoretical and numerical simulation combined with field measurement, the upper and lower cross bedding drilling is studied. Through the simulation and comparison of gas pressure at different extraction time and the gas pressure changes when the spacing of boreholes is 8 m, 10 m, and 12 m, the results show that, under the designed parameters, when the pressure value at the middle of the two boreholes starts to be less than 0.74 Mpa, the standard extraction time of the upper and lower cross strata boreholes is 160 days, and the most suitable spacing of boreholes is 10 m. Combined with the actual situation of Baode Mine, the extraction effect of cross drilling and parallel drilling was compared. The research shows that the predrainage effect of cross drilling is obviously better than that of parallel drilling. Cross drilling improves the predrainage effect, prolongs the action time of gas extraction by drilling, and effectively eliminates the risk of coal seam outburst.

Study on Influencing Factors and Countermeasures of Mine Gas Grade Identification

This paper analyzes the significance of mine gas grade identification, that is, dividing the mine into different gas grades, selecting different grades of explosion-proof equipment, selecting different technical protective equipment and implementing different ventilation gas management systems according to the air volume required for different supply of mine gas grades, and implementing graded management, which is economical, reasonable, safe and reliable to ensure mine safety production. According to the commonly used gas grade identification methods, the factors affecting the identification results are analyzed. Through the comparison of a large number of identification data, the analysis and research shows that the identification time, mine output and calculation method are the three main factors affecting the identification results. The problems easily occurred in the appraisal process are analyzed, mainly including the layout of appraisal measuring points, the analysis of mine gas source is not specific, the test of mine air volume data is not accurate, the calculation results of mine gas appraisal are wrong, and the influence of mining geological factors on gas emission is not considered. According to the influencing factors, this paper puts forward three corresponding countermeasures to improve understanding, strengthen organization and leadership and improve training quality, which has certain guiding significance to improve the accuracy of appraisal results.

Research on Surrounding Rock Stability Test of Tunneling Roadway under Complex Geological Conditions

Different geological conditions are often encountered in the excavation of coal mine roadways, with fault-fracture zone being the most commonly seen complex geological conditions. Fault-fracture zone is characterized by complex lithologic property and joint development and can easily cause safety accidents when excavation burrows through the fault. Therefore, grouting reinforcement of fault-fracture zone is often implemented to ensure coal mine safety production. Based on the tunnel excavation case of −530 - −650 m belt conveyor inclined roadway at Huainan Pan’er Coal Mine, borehole optical fiber and electrical testing technologies were applied to monitor and analyze the dynamics of the surrounding rock stability when roadway excavation passed through the F1 fault, and evaluate the effect of grouting reinforcement on fault-fracture zone. According to the results of optical fiber and electrical methods, the distributional characteristics and evolution patterns of strain and electric resistivity were analyzed. The research pointed out the distinct difference in variation characteristics of strain and electrical fields between grouted reinforced fault-fracture zone and normal rock strata sections. This indicates that the grouting reinforcement effectively improve physical properties of rock strata in the fractured section, the stability of the rock strata at the fault-fracture zone was effectively increased, the degree of fault activation and deformation was relatively small, and roadway surrounding rock basically retained its original properties, pointing to high stability.

Research method of pressure relief and permeability enhancement in low permeability coal seam: A review

Gas drainage can prevent accidents such as coal and gas outbursts and gas explosions, which is of great significance for coal mine safety production. The level of permeability directly determines the effect of gas drainage. Therefore, experts and scholars in related fields have conducted extensive research with regard to adopting different measures to increase the permeability of coal and thereby improve the efficiency of gas drainage. However, in analyzing, comparing, and summarizing the advantages, disadvantages, and adaptability of various methods, there are few review studies in the literature. First, this Review investigates the principles, processes, and effects of different methods and finds that each method has its own specific application conditions and limitations. Simultaneously, it classifies different stimulation methods according to the principle of stimulation, which are mainly divided into physical stimulation methods, chemical stimulation methods, microbial stimulation methods, and thermal stimulation methods. Then, for better field applications, this Review investigates emphatically these methods that are currently popular but still in the laboratory stage, such as acidification stimulation and freeze–thaw stimulation, and analyzes the experimental methods, principles, experimental effects, influencing factors, etc. Permeability represents the flow capacity of gas in porous media and thereby affects the efficiency of gas extraction. Therefore, this Review summarizes the influencing factor of permeability. Finally, this Review discusses the aspect that needs to be perfected and improved for different methods and points out the problems and possible development directions in the future.

Development and Application of Water Sealing Technology for Gas Drainage Boreholes.

The poor sealing effect of gas extraction boreholes causes low efficiency of gas extraction. As a consequence, the requirements of coal mine safety production are often not attained. The sealing effect of boreholes depends not only on the sealing material itself but also on the combination degree between the material and the hole wall and the structural change characteristics of the material during operation. Our theoretical analysis shows that the amount of liquid leakage increases with the gap width Δh in a cubic law, decreases with the sealing hole viscosity in a hyperbolic form, increases linearly with the diameter of the borehole, and increases with the eccentricity in a quadratic function. We have developed a PD sealing material that has good compactness and sealing effects, excellent water retention performance, and an expansion rate of 1.29. The material can generate secondary expansion through microscopic development, which is beneficial to improve the quality of the sealing hole. HV-CMC has good stability in plugging mucus. In addition, the manual pump has been redeveloped to be portable and also to overcome the blockage of the suction valve of the original device. In addition, the auxiliary device for drilling and sealing has been invented. The field application demonstrates that the gas concentration and flow pressure difference of the new sealing borehole can be maintained at a high level in a short period of time and then decrease slowly with time. The resulting improved sealing effect demonstrates that our new approach has important theoretical and practical significance for mine gas drainage.

Discussion on Function and Development Direction of Mine Survey in Coal Mine Safety Production

Discussion on Function and Development Direction of Mine Survey in Coal Mine Safety Production

Orientation underground exploitation method to develop for the Lang Vai of small scale antimol region, ​Tuyen Quang Province

Vietnam's mineral resources are very rich yet dispersed; the majority of ore mining are on a modest scale. One such mine is the Lang Vai antimony mine in Tuyen Quang province. The mine contains around 55,000 tons of main ore reserves with a concentration of 0.07 4.56 percent. The ore body is spread in the form of beds, veins, and steep slopes. With these sorts of mines, the issue for mining engineers is balancing technological indications, mining safety, and cheap production costs. If mechanized mining technology is used, capital recovery is not possible; if manual technology is used, productivity and safety are low, and the payback period is long. The building solution is simple, based on an examination of the features of such a mine, which is naturally placed of the ore body, the mechanical and physical qualities of the surrounding rock, and so on, with the objective of the shortest ore production time. simple. The article offers a strategy to approach the ore body through a vertical well combined with a through-seam furnace, an ore storage mining system, the building of a pipeline to prepare for production in the ore body, and a road drill construction technique. Breaking rock with 36 mm glass using a blasting technique. Simultaneously, compute some fundamental efficiency requirements based on the chosen plan.

Molecular structure characterization of coal under the water–rock interaction in acid mine drainage (AMD)

AMD weakens the compressive strength of coal pillar and threatens the safety of coal mine production. In order to study the effect of AMD on coal, this paper uses X-ray diffraction (XRD) and Fourier transform infrared (FTIR) test techniques to detect the molecular structure of coal samples treated with different immersion acidity and immersion time. The results show that with the increase of soaking acidity and soaking time, the layer spacing (d002) from 0.349 to 0.353 and La from 55.719 to 57.420 nm, showing a positive correlation; Lc from 1.85 to 1.66 nm and N from 5.31 to 4.71, showing a negative correlation. It shows that the original microcrystalline structure in the coal sample changes due to the chemical reaction of organic matter, the spacing and average diameter of the microcrystalline layers increase, the average height and the number of carbon layers decrease, and the degree of order gradually decreases. Aromatic hydrogen(farH), aromatic carbon(farc), the relative abundance of aromatic and aliphatic functional groups(I) and A(CH2)/A(CH3) gradually decrease, degree of condensation (DOC) and oxygen-containing structural(‘C’) gradually increase. The research results show the molecular structure characteristics of coal in AMD water–rock interaction, and provide a reference for studying the macroscopic characteristics of coal under the action of AMD.

The characteristic research on the flame retardant of calcification foam on the high temperature coal

The coal spontaneous combustion is an urgent issue to be solved for the mine safety production. In the present paper, a new flame retardant of the calcification foam is proposed to improve the prevention effectiveness on the high temperature coal. The molecular dynamics simulation shows that the calcification foam exhibits a superior water retention performance at the thermal environment than the original foam. Ca2+ enters the hydration layer of the calcification foam and expands the head groups distance by 22.27%. Ca2+ focuses on the second hydrated water shell around the head groups and restricts the water molecule drainage. The drainage rate decreases with the temperature rise according to the diffusion coefficient. The oil bath experiment explains that the drainage rate of the calcification foam is slower and the growth rate is only half of the original foam at 100–150 °C. The calcification foam successfully restrains the coal spontaneous combustion. The coal heating rate treated by the calcification foam decreases obviously and the maximum reduction of CO release achieves 60%. The calcification foam has a good plugging and water retention properties for coal with the average inhibition rate up to 75.36%. The calcification foam has a superior effectiveness on suppressing the flame development.

The Stability of Roadway Groups under Rheology Coupling Mining Disturbance

The deep roadway groups play an important role in transportation and ventilation in coal mine production. Therefore, it is very important to comprehensively analyze the coupling effect of rheological deformation and coal mining on the stability of the roadway groups. In this paper, the disturbance effects of different stop-mining lines on roadway groups under long-term rheology were investigated by numerical simulation, and the failure mechanism of roadway groups with large sections and multiple disturbances in a deep well was revealed. The results show that the long working face will lead to the collapse of key strata, and the influence range will spread to the adjacent roadway groups. When the distance between the working face and the stop-mining line is 100 m, the roadway groups cannot be affected by the working face mining, and the reserved width of the coal pillar can be determined to be 100 m, which increases the stability of the roadway’s surrounding rock and maintains the mine safety production. This paper aims to provide a reference for groups design and control under similar conditions.

Quantum Chemistry Calculation Study on Chain Reaction Mechanisms and Thermodynamic Characteristics of Coal Spontaneous Combustion at Low Temperatures.

The coal spontaneous combustion phenomenon seriously affects the safety production of coal mines. Aiming at the problem of complex coal molecular structure and incomplete reaction sequences at present, the mechanisms and thermodynamic parameters of coal spontaneous combustion chain reactions were explored by combining experimental detections and molecular simulations. First, the active groups on the surface of coal were obtained by Fourier transform infrared spectroscopy (FTIR), mainly including methyl (−CH3), methylene (−CH2), methyne (−CH), phenolic hydroxyl (−ArOH), alcohol hydroxyl (−ROH), carboxyl (−COOH), aldehyde (−CHO), and ether (−O−), and the coal molecular models containing functional groups and radicals were established. According to the charge density, electrostatic potential, and frontier orbital theories, the active sites and active bonds were obtained, and a series of reactions were given. The thermodynamic and structural parameters of each reaction were explored. In the chain initiation reaction stage, O2 chemisorption and the self-reaction of radicals play a leading role. In this stage, heat gradually accumulates and various radicals begin to generate, where the intramolecular hydrogen transfer reaction of a peroxide radical (−C–O–O·) can produce the key hydroxyl radical (−O·). In the chain propagation reaction stage, O2 and −O· continuously consume active sites to accelerate the reaction sequences and increase the temperature of coal, and index gases such as CO and CO2 generate, causing the chain cycle reactions to gradually form. The chain termination reaction stage is the formation of stable compounds such as ethers, esters, and quinones, which can inhibit the development of chain reactions. The results can further explain the reaction mechanism of coal spontaneous combustion and provide references for the development and utilization of chemical inhibitors.

Study on the infiltration mechanism of injecting chelating agent into deep low permeable coal seam

Coal seam water injection technology which provides a guarantee for coal mine safety production is significant for the prevention and control of coal mine disasters. The selection of additives is very important for the implementation of coal seam water injection technology. Although the research on additives has been extensive in recent years, the mechanism of additives which can increase the permeability of coal and change mechanical properties of coal is still unclear. After selecting the chelating agent as the water injection additive, we characterized the pore structure of coal by low temperature N2 adsorption, mercury injection, scanning electron microscopy, etc., and tested the strength of coal by uniaxial hydraulic testing machine, as a result, several interesting results were found. Firstly, the minerals in the coal seam will damage the permeability of the coal seam and impede the flow of water in the coal seam. Secondly, the chelating ligand can interact with minerals like calcite and dolomite. When the concentration of the chelating agent is 500 mg/L, Ca2+ can be detected in the immersion solution and the leaching concentration of Ca2+ is 43.76 times greater than that in the ultra-pure water immersion solution. The change of pH has a greater impact on the leaching concentration of Fe and Mg, while the change of solid–liquid ratio has a smaller impact on their leaching concentration. Thirdly, as the dissolution of minerals, the size and volume of pore in coal increase, specific surface area decrease, connectivity of pore become better, the permeability of coal increase by an average of 129%, which has a promoting effect on water injection. Fourthly, the existence of minerals will affect the mechanical strength of coal. The uniaxial compressive strength of coal decreases after the chelating ligands interacted with the coal and the pH of the solution and soaking time also obviously affect the strength of coal. These results are helpful to open up a new direction for the selection of water injection additives that can realize the green and safe mining of coal.