Mine Disaster Research Articles

Method and Validation of Coal Mine Gas Concentration Prediction by Integrating PSO Algorithm and LSTM Network

Gas concentration monitoring is an effective method for predicting gas disasters in mines. In response to the shortcomings of low efficiency and accuracy in conventional gas concentration prediction, a new method for gas concentration prediction based on Particle Swarm Optimization and Long Short-Term Memory Network (PSO-LSTM) is proposed. First, the principle of the PSO-LSTM fusion model is analyzed, and the PSO-LSTM gas concentration analysis and prediction model is constructed. Second, the gas concentration data are normalized and preprocessed. The PSO algorithm is utilized to optimize the training set of the LSTM model, facilitating the selection of the training data set for the LSTM model. Finally, the MAE, RMSE, and coefficient of determination R2 evaluation indicators are proposed to verify and analyze the prediction results. Gas concentration prediction comparison and verification research was conducted using gas concentration data measured in a mine as the sample data. The experimental results show that: (1) The maximum RMSE predicted using the PSO-LSTM model is 0.0029, and the minimum RMSE is 0.0010 when the sample size changes. This verifies the reliability of the prediction effect of the PSO-LSTM model. (2) The predictive performance of all models ranks as follows: PSO-LSTM > SVR-LSTM > LSTM > PSO-GRU. Comparative analysis with the LSTM model demonstrates that the PSO-LSTM model is more effective in predicting gas concentration, further confirming the superiority of this model in gas concentration prediction.

Numerical Multifield Coupling Model of Stress Evolution and Gas Migration: Application of Disaster Prediction and Mining Sustainability Development

At present, coal mining is gradually shifting towards deep areas, and coal mines under deep mining conditions are more prone to coal and gas outburst accidents. In this research, we aim to explain the causes and mechanisms of dynamic disasters, which are caused by the combined action of static load, gas, and dynamic load on tectonic regions in complex stress field environments. Through numerical simulation using COMSOL Multiphysics software, based on the geological conditions of a mine in Jilin Province, it was found that faults lead to abnormal stress in tectonic regions. The combined action of dynamic and static loads results in excessive stress, causing the fragmentation and displacement of the coal body, leading to coal mine disasters, thus disrupting sustainability. Additionally, the coal matrix gas entering fractures raises the gas pressure and leads to the accumulation of methane near earthquake sources. Dynamic loads accelerate gas desorption in coal and increase porosity and permeability, facilitating rapid gas migration. This influx of gas into the roadways exceeds safety limits. Then, based on these findings and on-site conditions, a set of sustainable measures for coal mines has been proposed. This research offers theoretical guidance for enhancing safety, stability, and sustainability in coal mining processes.

Research on the Law of Coal Pillar Spontaneous Combustion and Fire Prevention and Control Technology.

In coal pillar fires, the fire source is hard to be detected and the adjacent goaf is extremely likely to be affected. Such fires would give rise to thermal and dynamic disasters in mines, further causing casualties and environmental disruption. In this study, with the coal pillar spontaneous combustion (CPSC) accident in Chahasu Coal Mine taken as the research object, the oxygen uptake and limit of oxygen concentration of CPSC were explored. Based on the research results, a similar model was constructed, where a control group was used to simulate the hazardous area of CPSC in a bid to investigate the law of CPSC. Moreover, the polymer colloid perfusion system was constructed and the drilling parameters and perfusion process parameters were determined, and practices concerning spontaneous fire control were carried out. Here are the conclusions: First, air leakage in the coal pillar may lead to coal spontaneous combustion due to the impact of rib spalling, threatening 2-6 m above the middle of the coal pillar at a shallow position. Second, coal pillar grouting, injecting polymer colloids for cooling, and coal pillar cement reinforcement prove to be effective ways to prevent CPSC fires and combat recombustion.

Do ESG disclosures mitigate investors’ reaction on mining disasters? Evidence from Brazil

The purpose of this paper is to examine the investors´ reaction to the largest ecological disasters –Samarco (2015) and Brumadinho (2019)– occurred in Minas Gerais (Brazil). Applying a short-term event study analysis, we test the stock and Credit Default Swap (CDS) market´s on the mining sector. Moreover, a cross-sectional analysis is performed testing the effect of ESG disclosures on the market reaction –in terms of Cumulative Abnormal Returns, CAR– on the competitors of Vale S.A., the company involved in such ecological catastrophes. Our findings show a statistically significant reaction in both events. Investors´ react negatively and immediately in the case of Vale for both events; CARs are statistically significant for the shorter windows. However, investors react differently in the mining sector sample –excluding Vale–. While CARs are negative in Samarco, investors do so positively in the case of Brumadinho. In that sense, investors seemed as if they switch their perceptions from this first event –Samarco–in comparison to the most recent one –Brumadinho– rewarding the increase of ESG disclosures in the meantime and mitigating a negative contagion effect in the mining sector. The impact on the CDS market is also found positive in mining sector.

Investigation on a mobile fire extinguishing approach using liquid carbon dioxide as inert medium for underground mine.

Injecting carbon dioxide is the most effective means of preventing and extinguishing fires in sealing hazardous areas, but the traditional method slowly and remotely injects carbon dioxide gas into the well after gasification on the ground, which is dependent on the complete mine pipe network without cooling effect. To inject liquid directly from the tank with vacuum interlayer and heat insulating powder for rapid inerting and cooling, a new approach using track mobile platform to go deep into the underground mine disaster area is proposed, so the liquid can be delivered to the nozzle at the end of DN40 large diameter pipe, and the continuous gasification jet can be realized. The experimental results show that: (1) The liquid volume in a tank of vacuum degree within 2.0 Pa and 200 mm interlayer reduced no more than 15.5% after 48 days; (2) Taking the pressure in the tank as the power source, because of environmental differences inside and outside the pipe after 100 m pressure holding delivery, the physical form of liquid and gas could be converted instantly; (3) The continuous discharge time without ice blocking for a tank full of 2 m3 liquid was about 10.5 min under 25 L dual mode nitrogen pressurization, which is 1/12 of injection time after ground gasification; (4) Based on the temperature decrease trend measured at different positions, the cooling characteristics on liquid gasification jet path are quantified, and the calculation formula of temperature changing with time on the center line of liquid gasification jet is obtained. Through this new approach, the integration of vacuum insulated storage, safe mobile transportation, and continuous and rapid release with large flow can be achieved for the liquid carbon dioxide.

Effect of delay time of working face pressure change on airflow direction in gob: A simulation study

AbstractFor shallow buried mines, the cracks generated due to the mining activities will connect the surface ground and the working face through the gob, which may result in the gas exchange between the surface and underground. In this study, we proposed the gob gas flow model and verified its applicability based on the measured data on site in our previous research and discussed the effect of delay time of pressure variation between working face and surface ground on the airflow direction according to the simulation. The results suggest that the delay time of pressure variation is the main factor affecting the pressure difference between surface and working face and airflow direction. Due to the characteristics of the surface pressure changes, the effect of delay time on airflow in gob is small in a short time, but this effect gradually increases with time. According to the airflow law in a cycle of pressure variation, the airflow direction in the gob is predictable when the delay time reaches a certain value, which can be interpreted clearly on the surface pressure variation diagram. This research may provide references for the measures taken against mine disasters caused by different airflow directions. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

Promoting Sustainable Coal Mining: Investigating Multifractal Characteristics of Induced Charge Signals in Coal Damage and Failure Process

Monitoring and preventing coal–rock dynamic disasters are essential for ensuring sustainable and safe mining. Induced charge monitoring, as a geophysical method, enables sustainable monitoring of coal–rock deformation and failure. The induced charge signal contains crucial information regarding damage evolution, making it imperative and important to explore its temporal characteristics for effective monitoring and early warnings of dynamic disasters in deep mining. This paper conducted induced charge monitoring tests at different loading rates, investigating the multifractal characteristics of induced charge signals during the early and late stages of loading. It proposed the maximum generalized dimension D(q)max, multifractal spectrum width Δα, and height difference Δf as multifractal parameters for induced charge signals. Additionally, quantitative characterization of coal damage was performed, studying the variation patterns of signal multifractal characteristic parameters with coal damage evolution. This study revealed the induced charge signal of the coal body multifractal characteristics in the whole loading process. In the late loading stage, the double logarithmic curve demonstrated some nonlinearity compared to the previous period, indicating the higher non-uniformity of the induced charge time series. D(q)max and Δα in the late loading stage were higher than those in the early stage and increased with loading rates. As coal damage progressed, there were significant jumps of D(q)max in both the early and late stages of damage, with larger jumps indicating richer fracture events in the coal. The width Δα showed an overall trend of increase–decrease–increase with coal damage evolution, while the height difference Δf fluctuated around zero in the early stage of damage development but increased significantly during severe damage and destruction. By studying the multifractal characteristics of induced charge signals, this study provides insights for the early identification of coal–rock dynamic disasters.

Numerical simulation study on the evolution law of mechanical properties of different metamorphic coals after heat treatment.

In order to study the effect of temperature on the structure and mechanical properties of coal with different metamorphic degree. Three coal samples with varying degrees of metamorphism were chosen for analysis. The discrete element software PFC2D is used to simulate the heat treatment and compression of coal. The findings indicate that during the heating process, low-order coal exhibits noticeable thermal cracks at an early stage, while thermal crack development in middle-order coal is concentrated in the later stages. In contrast, high-order coal demonstrates a more stable macroscopic structure. The strength and stiffness of low rank coal show the lowest value and decrease significantly within 135°C. However, the strength and stiffness of medium rank coal decrease significantly after 135°C. The changes of mechanical properties and damage modes of coal caused by thermal damage are often ignored, which may lead to the deviation of design and research results from the actual situation. Therefore, this study is of great significance to the prevention and control of coal mine disasters.

Assessment of the influence of DTM quality on dam rupture simulation processes

Computer programs applied to disaster simulation are widely used and widespread today, taking as input various data types, from specific to the application area to DTMs (Digital Terrain Models). This need for data input and, in particular, data related to relief is very relevant in prediction procedures for forecasting catastrophes, such as the failure of tailings mining deposit dams. Therefore, it is of fundamental importance to know and quantify the quality of this input data in question, in order to effectively serve this application. To this end, in this research, several tests were carried out, using as a reference for best results those obtained with the introduction of DTM from a LIDAR (Light Detection and Ranging) flight survey, this data being used as one of the primary and input into HEC-RAS (Hydrologic Engineering Center-River Analysis System). Subsequently, these same data had their spatial resolution degraded, that is, the pixel size increased, generating models with worse quality for new inputs and obtaining new simulation results of mining dam failures. The test area of the B1 Dam, located in Brumadinho-MG, Brazil, was used as a laboratory, where one of the biggest mining disasters in the world recently occurred and, for which, there are real data from the area affected by the dam collapse. The results obtained demonstrated that the use of an DTM with a spatial resolution of at least 2.5 meters or better, with DTM class A cartographic quality compatible with the most recent Brazilian standard, would guarantee reliable results.

The digital twins for mine site rescue environment: Application framework and key technologies

In the era of widespread adoption of the new generation of information technology, the crucial development directions for mine site emergency rescue include systematization, precision, intelligence, and diversification. Chinese mines have extensively invested in information technology construction in the field of safety. However, despite these efforts, they still face complex and changing situations following mine disasters. It is often difficult to comprehensively capture all information and devise appropriate rescue plans during the site rescue process. In this context, herein, the scientific connotation of the digital twin system for mine site rescue environment (DTS-MRE) is proposed. Further, its overall architecture, functional characteristics, and key technologies essential for system construction are introduced. The application of DTS-MRE is expected to aid the monitoring, simulation, emulation, coordination, prediction, and control of the entire process of mine emergency rescue governance; increase the success rate of mine emergency rescue; and provide scientific and technological support for mine safety emergency rescue.

A Struggle for Survival and Identity: Families in the Aftermath of the Castle Gate Mine Disaster

A Struggle for Survival and Identity: Families in the Aftermath of the Castle Gate Mine Disaster

Victims of the Castle Gate Mine Disaster, March 8, 1924

Victims of the Castle Gate Mine Disaster, March 8, 1924

Molecular simulation of the effect of anionic surfactant on methane diffusion in coal

Coal seam water injection is one of the important means of coal mine disaster prevention and control, which helps to reduce gas concentration. Anionic surfactants can change the hydrophilicity of coal to enhance the wetting effect of coal seam water injection and inhibit the diffusion of methane. However, the research on the effect of surfactants on the diffusion process of methane is still relatively weak. In order to explore the influence mechanism of anionic surfactant on coal surface wettability and methane diffusion from a microscopic point of view. Using wiser coal model and two commonly used anionic surfactants, sodium dodecyl benzene sulfonate (SDBS) and sodium dodecyl sulfate (SDS), the surfactant/water interface configuration, water/coal contact angle configuration and coal seam methane diffusion configuration were constructed. The interfacial stability of surfactant and water was discussed, and the wetting modification effect of surfactant on coal surface and the law of gas diffusion were analyzed. Finally, by studying the microscopic properties of each molecule in the simulation system, the adsorption mode of surfactants, the hydrophilicity of polar groups, the number of hydrogen bonds and the change of the pore volume in the coal seam system were analyzed, and the wetting modification mechanism of surfactants on coal surface and the inhibition effect of methane diffusion were discussed. The results show that with the increase of surfactant concentration, the interface formation energy is constantly enhanced, and the absolute value of electrostatic energy gradually increases, making the effect between surfactant and water stronger. The contact angle of coal surface under the action of SDS surfactant is the smallest, which is 36.230°, indicating that SDS surfactant has the best effect on the wettability of coal surface. The amount of methane diffusion in the surfactant action system decreased significantly compared with the pure water system, and the distribution of methane in the coal seam increased, indicating that the interaction between methane and coal is enhanced under the action of surfactant. With the increase of surfactant concentration, surfactant molecules are easier to spread on the surface of coal seam, and the wettability of coal surface increases. The research results can provide some research ideas and reference significance for anionic surfactants in the prevention and control of coal mine gas disasters.

Impacts of mining disasters on the ambulatory care of the Brazilian national health system: the cases of Mariana and Brumadinho/Brazil

BackgroundDisasters are events that bring with them effects that contribute to the disruption of the normality of a population and thus highlight the vulnerabilities of the health system. In Mariana and Brumadinho, the collapse of the dam of ore tailings brought with it several impacts that were felt in the short term and will be felt in the medium and long term. And that by being intensely intertwined with issues of economic and productive nature, has as its meaning an uninterrupted result of its activities.MethodsThrough the DATASUS database, two specific variables were chosen to perform the analysis: the approved amount and the approved value. For this research, a methodological device, the segmented regression line, was used to observe the influences that the disasters that occurred in Mariana and Brumadinho had on the ambulatory health systems.ResultsThe results of the segmented regression line show that, with Mariana, the amount approved continued to grow throughout the period, which shows that there was no change because of the disaster. There was a reduction in spending. In Brumadinho, regarding the amount approved, there was an upward trend in the disaster’s month, which did not change immediately afterwards, and regarding expenditure, the growth pattern was maintained in all three periods. Corroborating this data, the relative and absolute base elements show an increase in the amount approved and in the number of services provided at various posts compared with Minas Gerais.ConclusionsBased on the findings, it was possible to understand that although disasters exert an influence that may have some effect on the health system, the lack of significance sometimes cannot be interpreted as a lack of impact on the disaster. The segmented regression line outlines some effects that are not conclusive but indicative of a numerical interpretation and a trend interpretation.

Spatial and Temporal Characterization of Mine Water Inrush Accidents in China, 2014–2022

Currently, water inrush accidents in China’s coal mines are mainly under control, but occasionally, grave water inrush accidents still occur, causing significant casualties and economic losses. Existing studies have primarily focused on accident statistics, and the research on the trend of accident evolution is becoming obsolete to match the current context of coal resource development. This study analyzes the water inrush accidents in China’s coal mines between 2014 and 2022. It investigated the spatial and temporal distribution of accidents, the level of accidents, and the extent to which water prevention and control measures vary by zone in coal mines. The study results showed that from 2014 to 2022, water inrush accidents in coal mines exhibited a “decline-stability-fluctuation” stage change pattern. Additionally, the location of water inrush accidents has shifted westward. Paying particular attention to preventing and controlling water disasters in coal mines within the west development zone is crucial. The water disaster accidents in China’s coal mines have been effectively controlled, but the problem of unequal levels of preventing and controlling water disasters in coal mines persists. This study can provide a reference for the safe and efficient production of coal mines and the control of the number of deaths in mine water hazard accidents.

Research on Spatiotemporal Heterogeneity of the Impact of Earthquakes on Global Copper Ore Supply Based on Geographically Weighted Regression

The large and super large copper deposits worldwide are mainly distributed in the Pacific Rim and Gondwana metallogenic domains, and they are highly coupled with the spatial location of seismically active zones. Major copper-producing countries such as Chile are located in areas with high seismic activity. Earthquakes often cause copper mines to shut down, copper prices to soar, and even mining disasters, affecting the stable supply of global copper. In order to study the impact of earthquakes on the global copper ore supply, information on resource endowments, production, and earthquake data from the past 30 years are collected. This article mainly analyzes (1) the spatial correlation between earthquakes and copper mine projects, and the spatial characteristics of earthquakes’ impact on copper mine production, using correlation analysis and geographically weighted regression (GWR); (2) the impact of sudden earthquake events on the export volume and price of copper mines from the perspective of time, using the earthquake index constructed based on the magnitude of the earthquake, the depth of the epicenter, and the distance from the copper mine. The results indicate that the regions with high spatial correlation between copper mine projects and earthquakes are mainly located along the Pacific coast of South and North Americas. Earthquakes can lead to an increase in copper prices, but they will fall significantly in the short term. The impact of earthquakes on export volume generally has a delay period of 1–2 months, resulting in a short-term decrease in export volume. This article quantitatively evaluates the impact of earthquake risk on the supply chain from both spatial and temporal dimensions, providing reference for supply chain risk monitoring, risk impact assessment, and prediction. On the basis of the research results of this article, mineral resource management departments can quantitatively evaluate the spatiotemporal impact of natural risks such as earthquakes on the supply chain, adjust management policies in a timely manner, and improve the level of refined management of supply chain risks.

A multi-biomarker approach to verify chronic effects on Eisenia andrei earthworms exposed to tailings from one of the world's largest mining disasters

Mining is of great relevance to the global economy, but its activities are challenging due to socio-environmental impacts. In January 2019, an iron ore tailings dam collapsed in Brumadinho (Minas Gerais, Brazil) releasing 12 × 106 m3 of tailings, causing human losses and devastation around 3.13 × 106 m2 of a watershed. In this context, the present study aimed to investigate the potential toxic effects of tailings from the collapsed dam using earthworms Eisenia andrei as a model organism for terrestrial environments. An extensive set of tests was performed, including behavioral (avoidance), acute (mortality and biomass) and chronic tests, such as biomass, reproduction and cytotoxicity (viability and cell density and change in coelomocyte pattern). The physical-chemical characterization revealed a higher density of the tailings in relation to the control soil, which can result in physical changes, such as soil compaction and surface sealing. Aluminum, Ca, Fe, Hg, Mg, Mn, K, Na and P registered higher concentrations in the tailings compared to the control soil, while Total Nitrogen, Total Organic Carbon and Organic Matter were higher in the natural soil. Based on the avoidance test, an EC50 of 27.18 ± 2.83% was estimated. No lethality was observed in the acute exposure, nor variations in biomass in the acute and chronic assays. However, there was a tendency to reduce the number of juveniles in relation to cocoons in the proportions of 3125; 12.5 and 25%. Significant changes in viability, cell density and pattern of amebocytes and eleocytes were observed up to the 35th day of exposure. A multi-biomarker approach (Integrated Biological Response version 2) indicated concentration-dependent effects and attenuation of cellular changes over time. These are the first results of chronic effects on earthworms exposed to tailings from the B1 dam. Despite being conclusive, we highlight the possible heterogeneity of the tailings and the necessary care in extrapolating the results.

Spontaneous Coal Combustion, Direct and Indirect Impact on Mining in China: A Prospective Review and Proposal of a Five-Level Comprehensive Mine Safety Management Structure (5L-CMSMS) Coupled with Hazard Zoning and Barrier Systems

ABSTRACT To prevent, predict, control, and reduce the catastrophe caused by spontaneous coal combustion (SCC), and the subsequent direct and indirect adverse impact on the environment and health, this review proposed a five-level comprehensive mine safety management structure (5 L-CMSMS) to augment the already existing technological interventions. The 5 L-CMSMS features a 3-Phase Model and a continuous review of safety measure/accident prevention program handled at the national level and which can be replicated by all the five levels (i.e. national, provincial, city, district, and the mine). Additionally, hazard zoning and barrier systems to augment the 5 L-CMSMS and the other advanced technology currently being employed to prevent most mine disasters are also proposed. With all incidents and accidents happening principally in the mines, the implementation of a constructive monitoring and supervision team at the facility level by using safety committees, safety officers, and unit heads can reduce the incidents and accidents drastically. With regular and proper safety training, assessment and evaluation, and awareness creation the coal mine safety risk management which is a systematic project and an interconnected organic whole, involving multiple subjects such as enterprise management, enterprise employees, government regulators, and the external environment can be salvaged.

Slope Failure of Shilu Metal Mine Transition from Open-Pit to Underground Mining under Excavation Disturbance

The instability of slopes and ground subsidence caused by the conversion from open-pit to underground mining are important aspects of mining disaster research. This study focuses on the instability of slopes and ground subsidence during the conversion from open-pit to underground mining in the Beiyi mining area of the Shilu iron ore mine. Using numerical simulation and analysis, this study establishes a mechanical analysis model to assess the rock stability and movement of rockfall. The research findings indicate that there are significant stress concentration phenomena in the surrounding and floor areas of the goaf during the mining process. The collapse zone mainly develops in the western area before and after a certain level of mining and then shifts to the eastern part of Beiyi area. Surface subsidence expands after mining at a certain level, resulting in a large-scale disturbance area. Furthermore, the eastern slope experiences extensive landslides. This study suggests the continued monitoring of landslides and slope stability in specific areas of the mine. The research results can help us to understand the stability of the open-pit to underground rock mass in Hainan, judge the development trend of the surface subsidence range, and provide a reference for the stability evaluation of the rock mass mined by the open-pit-to-underground caving method.

Numerical study on the influence of fault orientation on risk level of fault slip burst disasters in coal mines: a quantitative evaluation model

Numerical study on the influence of fault orientation on risk level of fault slip burst disasters in coal mines: a quantitative evaluation model