Underground Collieries Research Articles

Safety Monitoring and Auto Alert System in Underground Collieries

In the current scenario, significant mine disasters often occur due to explosions and fires. The occurrence of unexpected underground mine landslides poses a significant threat to miner safety, leading to fatalities. Consequently, the proposed system actively monitors key parameters and issues alerts to miners, aiming to mitigate this risk. The system primarily focuses on monitoring gas levels, air quality, temperature, and vibrations in underground mines, with the data being continuously recorded and stored in the ThingSpeak cloud. Visualization of the data is achieved through field charts created within the designated channel. The cloud-stored data is linked with MathWorks to predict missing values, providing a basis for proactive measures. The predicted missing values are then stored in a separate channel on ThingSpeak for continuous chart visualization. This data, complete with timestamps, can be exported to excel for further analysis and application. The scenario of the coal mine is monitored and regular reports are sent to the personnel’s mail which is automated in Thingspeak. In the event of an explosion, the rescue team is promptly notified through SMS alerts using a GSM modem.

Investigation of a conveyor belt fire in an underground coal mine: Experimental studies and CFD analysis

Coal produced in underground mines is transported to the surface by means of conveyor belts throughout long roadways. The combustion of belts puts a large number of employees at great risk. Underground collieries differ from other underground mines -due to the combustible nature of the product. The most prevalent cause of belt fires in underground coal mine is spontaneous combustion due to oxidation of the coal, which also enables the conveyor belt to burn over time. In 2014, a belt fire in an underground coal mine in Manisa-Soma, Turkey caused 301 fatalities. A study has been conducted on this accident for approximately 3 years, consisting of combustion tests in a purpose-built research gallery, comparison of the test results with mine records of the accident, and CFD modelling of the mine environment. The intensity of the fire was sufficient to redirect the air flow underground, causin large amounts of toxic gases to fill almost the entire mine in approximately 15 minutes. It is recommended that CFD analysis be used in planning emergency action strategies in underground mines.

Prevalence of coal worker's pneumoconiosis: a systematic review and meta-analysis.

Global prevalence trend and regional differences of coal worker's pneumoconiosis (CWP) remain unclear. This study aimed to provide systematic and comprehensive evidence for the global prevalence of CWP. Literature research for studies that reported prevalence of CWP was conducted in PubMed, CNKI, and Web of Science. The identified studies were strictly screened according to predetermined inclusion and exclusion criteria. The pooled prevalence of CWP in different periods and regions was calculated. A total of 37 studies were included after screening, and data from the Coal Workers' Health Surveillance Program was additionally included in the meta-analysis. The global pooled prevalence of CWP decreased from 23.33% (95% confidence interval [CI]: 18.03%, 28.62%) before 1970 to 6.00% (95% CI: 4.11%, 7.90%) in 1981-1990, but indicated a rebound (10.35%, 95% CI: 8.08%, 12.62%) in 1991-2000 and finally dropped to 2.29% (95% CI: 2.06%, 2.51%) in 2011-2020. In the recent 30 years, the top three pooled prevalence of CWP was found in Europe, China, and the USA, respectively. Few articles have reported the prevalence in developing regions, but available evidence indicated that the prevalence in developing regions was much higher than that in developed regions. Higher pooled prevalence was observed in studies which reported larger number of miners in collieries, older average age of miners, underground collieries, and longer dust exposure time. The global prevalence of CWP indicates a rebound in 1990s, but the overall trend is downward in the recent 60 years. The prevention and treatment of CWP should be currently emphasized in developing countries.

Ecological and geochemical impact of an underground colliery waste discharge to a river

This study investigated the impact of mine wastewater disposal to a nearby river (the Bargo River). Mean electrical conductivity (EC) increased in surface waters below the mine discharge, rising more than six times from (219.5 μS/cm) upstream to 1551 μS/cm below the waste inflow. River pH increased from 7.12 (upstream) to 8.67 (downstream). The mine discharge strongly modified the ionic composition of the river. The mean concentration of several metals in the river were increased due to the mine wastewater. Nickel increased from 1.0 μg/L (upstream) to 32 μg/L (downstream). Zinc increased from 3.5 μg/L (upstream) to 23.5 μg/L (downstream). Our study also assessed the biological uptake of pollutants by growing weeping willow (Salix babylonica) cuttings in mine wastewater and contrasting to ‘control’ cuttings grown in river water from upstream of the mine. After growing in the laboratory for several weeks, the cuttings accumulated metals, dominated by barium, strontium and lithium. Results from the study constituted one of the most detailed geochemical and ecological studies investigating the impact of the coal mine waste discharge to an Australian river. Recommendations are suggested for improved regulation of the mine discharge to reduce its wastewater environmental impact.

Determination of Performance Analysis for an Underground Colliery Utilizing Mechanized Production System

Performance is one of the most important parameters for today’s business organizations. An organizationthat is low on performance, no matter how much high quality products they have, cannot take the share they desirefrom the market. It is the inevitable result for organizations with low performances to lose money and get closed down.Nowadays performance is measured in many ways. In this work; the production performance of Ömerler Colliery,which is the only government controlled mechanized lignite mine authorized under the Western Lignite Corporation(WLC) and the factors that caused performance decrease has been determined. In order to gain performancemeasurements; effectiveness, efficiency and productivity criteria have been used and performance indexes have beenacquired. As the result of the performance analysis, it is understood that there has been malfunctions with; in order; beltconveyor, chain conveyor, shearer and fortification that has been effective in the decrease of performance. Performanceindexes, which are barely derived from the multiplication of performance parameters, are examined and it is deductedthat the highest relation is achieved for the efficiency parameter with a correlation constant (r) of 0.9489 and a certaintyconstant (R²) of 0.9005 while the lowest relation is obtained for the efficiency parameter with a correlation constant (r)of 0.4621 and certainty constant (R²) 0.2135. With this acquired result it has been determined that by only measuringeffectiveness, performance detection cannot be made.

Determination of Performance Analysis for an Underground Colliery Utilizing Mechanized Production System

Performance is one of the most important parameters for today’s business organizations. An organizationthat is low on performance, no matter how much high quality products they have, cannot take the share they desirefrom the market. It is the inevitable result for organizations with low performances to lose money and get closed down.Nowadays performance is measured in many ways. In this work; the production performance of Ömerler Colliery,which is the only government controlled mechanized lignite mine authorized under the Western Lignite Corporation(WLC) and the factors that caused performance decrease has been determined. In order to gain performancemeasurements; effectiveness, efficiency and productivity criteria have been used and performance indexes have beenacquired. As the result of the performance analysis, it is understood that there has been malfunctions with; in order; beltconveyor, chain conveyor, shearer and fortification that has been effective in the decrease of performance. Performanceindexes, which are barely derived from the multiplication of performance parameters, are examined and it is deductedthat the highest relation is achieved for the efficiency parameter with a correlation constant (r) of 0.9489 and a certaintyconstant (R²) of 0.9005 while the lowest relation is obtained for the efficiency parameter with a correlation constant (r)of 0.4621 and certainty constant (R²) 0.2135. With this acquired result it has been determined that by only measuringeffectiveness, performance detection cannot be made.

Experimental study on the inhibitory effects and mechanisms of crystalliferous water-containing mineral salts

ABSTRACTIn underground collieries, wide application of traditional inhibitors needs a large quantity of water, and there is a problem on getting water nearby. A sloping terrain leads to an uneven distribution of inhibitor solution concentration because of its fluidity. With the loss of water, traditional inhibitors are out of effect. To solve the above three issues, crystalliferous water-containing mineral salts, Na2S2O35H2O, CaCl26H2O, MgCl26H2O and their compound inhibitors, were used to inhibit coal samples in this study. Inhibited coal samples were heated in a programmed heating device, and Fourier transform infrared spectra of coal samples before and after the treatment were made. The results show that the inhibition mechanisms of crystalliferous water-containing mineral salts are a combination of physical and chemical ones, and CaCl26H2O is the most effective inhibitor among the crystalliferous water-containing mineral salt inhibitors selected in this study. Compared to the raw coal sample, not only does CaCl26H2O reduce the amount of CO generated from heated coal samples, but also it prevents functional groups of coal from being oxidized in the process of oxidation. Furthermore, from the perspective of functional groups, the inhibitory and catalytic effects of MgCl26H2O on coal were interpreted. Among compound inhibitors, the one made of Na2S2O35H2O, CaCl26H2O and MgCl26H2O with a mass ratio of 1: 1: 1 is the most effective. The coal sample treated with the compound inhibitor released less CO, but lots of functional groups (–OH,–CH2–, etc.) are converted into the C–O group. Finally, the analysis reveals that CaCl26H2O has the best inhibitory effect.

Assessment of workplace accident risks in underground collieries by integrating a multi-goal cause-and-effect analysis method with MCDM sensitivity analysis

This study introduces a method using a multi-goal fuzzy cognitive map (FCM) and multi-criteria decision making based on sensitivity analysis to assess the risks associated with working accidents in underground collieries. Safety, stoppage in operation, and operational and capital costs are considered as the main goals during the FCM process with significant emphasis on safety. Workplace accidents data from Kerman underground collieries are statistically evaluated to find the degrees of occurrence probability, severity, and work-disability duration as the main risk factors. The causes and effects of accidents are analyzed using FCM based on three goals and the effects of risk factors. A sensitivity analysis on the weights of the goals is conducted with the aim of increasing the workplace safety in TOPSIS environment after solving the designed multi-goal FCM. Results indicate that “gas poisoning,” “roof fall,” and “debris and destruction” take the first three ranks and impose high risks to the system. By contrast, “collision, hit, and crash” presents the lowest risk among all accidents.

Increased Water Pollution After Closure of Australia’s Longest Operating Underground Coal Mine: a 13-Month Study of Mine Drainage, Water Chemistry and River Ecology

This study investigated the water pollution impact of mine drainage from an underground colliery that had stopped mining 3 years earlier. After more than a century of operation, the mining stopped, pumping ceased and groundwater accumulated, causing the flooding of the deepest sections (c. 15%) of the mine workings. The mine then began free-draining to the adjacent Wingecarribee River. The closure and flooding triggered acid mine drainage that has resulted in mildly acidic pH and higher concentrations of several metals. Of greatest environmental concern were ecologically hazardous concentrations of three metals: nickel (418 μg/L), zinc (1161 μg/L) and manganese (11,909 μg/L) in the mine drainage. Such concentrations are some of the highest concentrations reported for these metals in drainage from an Australian coal mine and are 2.5 to seven times higher than when the mine was operating. The concentration of nickel and manganese were stable, but zinc gradually declined throughout the 13-month study. The inflow of the drainage increased the concentration of the three metals in the river, causing exceedance of water quality guidelines for protection of aquatic species. The ecological impact of the mine drainage was substantial, causing a 63% reduction in family richness and a 90% reduction in proportion of invertebrates from the known pollution-sensitive orders (Ephemeroptera, Plecoptera and Trichoptera). Literature suggests the pollution could continue for decades. Of additional concern is that the mine drainage is currently untreated and pollutes a river in the water catchment of Australia’s largest domestic water supply reservoir.

Hazard mitigation in coal mines

Today’s world witnesses increased number of mine accidents caused due to explosion and fire. When the methane gas concentration goes high, it causes fire leading to explosion. In this paper, an IoT based system is proposed to ensure safety to the mine workers in underground collieries. The proposed system consists of DHT-11 sensor to monitor the temperature and humidity of coal mines. When the gas sensor detects high methane gas level, blower is activated so that the atmospheric air can be pumped in from outside to dilute the gas concentration. The smoke sensor is also used to detect the fire. In case of any abnormality in any of these parameters the buzzer sounds. All these parameters are uploaded to the cloud directly so that the people at the control station can be well informed of the underground mines.

MRPN Technique for Assessment of Working Risks in Underground Coal Mines

ABSTRACT Accidents in underground collieries, under geological and geotechnical uncertainties, cause some irrecoverable consequences for workers. Recognizing and studying the effective factors in the occurrence of such accidents have a very crucial impact on improving worker safety and reducing mining costs. This paper introduces a new and beneficial technique named “modified risk priority number (MRPN)” for recognizing and assessing those risks which may cause working accidents in Iranian underground collieries. The available qualitative data from the mines was quantified using standard tables established for risk assessment. The technique was exemplified using data from mine accidents in Kerman and East-Alborz regions. Roof-fall was found to be the most significant risk factor in the mines that were investigated.

Experimental investigation of applying MgCl2 and phosphates to synergistically inhibit the spontaneous combustion of coal

Spontaneous fire hazard in underground collieries threatens the safe production of coal. Thus, globally, there is a growing interest in identifying and adapting novel methods for inhibiting the spontaneous combustion of coal. Although Cl-containing minerals exhibit retardant properties in the low-temperature range, they fail to control the combustion of coal at high temperatures. Therefore, to control the fire hazard caused by spontaneous combustion of coal at high temperatures effectively, phosphates and MgCl2 were innovatively used as synergistic inhibitors for suppressing self-ignition of coal. Laboratory tests such as thermal analysis, infrared spectrum analysis and oxidation analysis were performed to evaluate the behavior of coal samples before and after treatment. Experimental results indicated that the combined utilization of MgCl2, Zn3(PO4)2, and (NH4PO3)n could significantly reduce the heat emission during coal combustion, as well as the yield rate of CO. The optimal effect can be obtained with a Cl-to-P ratio of 2:1. In addition, functional groups such as OH and CH2 in treated samples decreased markedly. Hence, underground coal fire can be prevented more effectively using a combination of Cl and P, instead of using Cl-based retardants alone.

Long term changes in the concentration of radium in discharge waters of coal mines and Upper Silesian rivers

According to the latest guidelines of the International Atomic Energy Agency (IAEA, 2016), coal mining is one of the most important contributors to occupational exposure. Coal mining contributes about 45% of the total annual collective dose obtained by workers due to the exposure at places of working. One of the sources of exposure in mining are formation brines with elevated concentrations of natural radionuclides, the most common are radium 226Ra and 228Ra. Radium isotopes often occur in formation waters in underground collieries in the Upper Silesian region (USCB) in Poland. Significant amounts of radium remain underground in the form of radioactive deposits created as a result of spontaneous deposition or water treatment. This phenomenon leads to the increase of radiation hazard for miners. The remaining activities of 226Ra and 228Ra are released into the rivers with mine effluents, causing the contamination of bottom sediments and river banks.The results of radioactivity monitoring of effluents and river waters are presented here to illustrate a trend of long-term changes in environmental contamination, caused by mining industry in the Upper Silesian Region.

Process Model and Digitalization of the Coal Gas Outburst Prevention

Regional coal gas outburst prevention has become the prerequisite of coal mining in the most China underground collieries. It touched on miners’ lives so closely, but especially lacked of digitalization due to the hostile working environment, sightless strata reserves, complicated and long-time workflow. By synthesizing the vital rules issued by China governments and various techniques of coal gas outburst prevention, we proposed a novel process model for them embodied as a logical workflow. The model consisted of two operation links and two judging nodes, and dealt with three types of data. Then an easy-use and practical process data management software system was developed. By testing in Qinan colliery, the system was proved to be fully considering user experience and helpful to promote digitalization of coal gas outburst prevention. Compared with the traditional management, the digitalization might help engineers identify anomalies more quickly and avoid gas accidents in time. DOI : http://dx.doi.org/10.11591/telkomnika.v12i4.4240

A Novel Tracking and Warning Method for Gas Pre-Drainage Project Based on <i>X-R<sub>s</sub></i> Control Chart

To well develop coal gas and prevent gas outburst accidents, gas pre-drainage project has become the prerequisite of coal mining in underground collieries. Its construction quality determined drainage effect as well as touched miners lives closely. Based on the X-Rs control chart, a novel tracking and warning method for the gas pre-drainage project was proposed. Firstly, the data structure of upward cross-seam boreholes that were widely used in gas pre-drainage project was built. As time went by, the construction data of boreholes formed multivariable time series. Using the difference transformation between construction and design, the inspection data series of boreholes construction was designed. After that, the complete X-Rs control chart was implemented, in which by three types of anomaly characteristics the tracking and warning of the construction quality was accomplished.

The influence of operating loads on the state of stress and strain in selected load-bearing elements of a tower-type headgear structure / Wpływ obciążeń eksploatacyjnych na stan naprężenia oraz przemieszczenia wybranych elementów nośnych konstrukcji basztowej wieży szybowych

Abstract The headgear structure allows the conveyance to be moved over the shaft top to the loading (unloading) point, at the same time it keeps in place the rope pulleys while tower-type headgear structures also accommodate the entire winder installations. The headgear is where the final stage of the hoisting installation is located and where the surface transport systems begin. These aspects strongly impact the actual shape of the tower, its height and in some cases determine the design of the entire winding gear. In order that all the headgear functions should be provided, it is required that the ultimate state conditions should be maintained throughout its entire service life. In order to assess the critical service conditions, the computation procedure should be applied based on design loads and fatigue endurance parameters. The computations of characteristic loads acting on the headgear structure use the developed model of the system based on the dynamic analysis carried out for a specific case: a hoisting installation operated in one of the underground collieries in Poland. The maximal and minimal loads acting on a Koepe pulley and those required for the system operation are determined accordingly. The laws of dynamics provide a background for finding the forces and moments of forces acting in the components of the driving system (including the electric motors and pulley blocks) for the specified loading of the Koepe pulley. Underlying the numerical FEM model of the tower-type headgear structure are the technical specifications of the analysed object and FEM calculations followed by endurance analysis to find the state of stress in structural elements of the headgear under the typical service conditions. The results help in assessing how the design of the hoisting installation should impact on safety features of load-bearing elements in the headgear structure.

Upscaling laboratory results for water quality prediction at underground collieries in South Africa’s Highveld Coalfields

The prediction of future acidity and water quality is a key aspect of water management in mining environments. In this paper, different prediction techniques tested in an isolated underground compartment at a colliery in the Highveld Coalfield of South Africa are discussed. Considerations for upscaling these results are explained, and a methodology for upscaling is tested at this facility. Over 30 samples were collected around the compartment and through cored boreholes. These samples were tested using acid–base accounting tests, humidity cells, and mineralogy. From this, an integrated interpretation of potential water quality evolution was made, supported by detailed water quality sampling with the use of surface boreholes, stratified sampling underground, and pumped qualities over a period of two years. The results show that analytical tests play an integral role in water quality predictions at underground collieries. The results also show that, despite the vast differences between laboratory test conditions and the situation in the field, by taking site conditions into account to properly contextualise the results, improved predictions of expected water quality can be obtained.

Remote control, signalization and communication system at Eynez fully mechanized underground Colliery, Turkey

The peculiarities of application of the mine observation system Senturion 600 are considered for continuous gas control at Eynez underground colliery.

Numerical investigation of coal and gas outbursts in underground collieries

Coal and gas outbursts are a complex catastrophic unstable phenomenon that involve the ejection of large volumes of coal, and are often accompanied by gas, such as methane, carbon dioxide or a mixture of the two. Coal and gas outbursts are prevalent in deep and gassy mines where face advance rates are rapid, and where gas drainage is either poor or absent. The occurrence of progressively larger coal and gas outbursts, and the potential for the catastrophic collapse of coal pillars, is of increasing importance as mining is extended deeper in seams rich in methane and other hydrocarbons. A unique coupled gas flow and solid deformation numerical model, viz., RFPA 2D-GasFlow, has been developed and is applied to simulate the evolutionary process of such catastrophic coal failures in underground collieries. The finite element model, which incorporates the physics of gas flow in the coal seam, the physics of coal deformation and instantaneous failure, and the cross-couplings between them, is proposed. The model also incorporates small-scale variability in deformation modulus and strength of the coal and surrounding rock. The variability in modulus and strength is distributed via a fine-scale resolution model according to the Weibull distribution, where the distribution parameter determines the level of heterogeneity. This numerical model is applied to simulate the whole process of coal and gas outbursts, including stress concentration, coal fracturing, gas pressure-driven expansion, and outburst. The instantaneous outburst process and associated stress fields, gas pressure gradients and displacement vectors are presented step by step. The numerical simulations indicate that the instantaneous outburst is a complex phenomenon involving interactions between gas pressure, stress and the physico-mechanical properties of the coal, and it can occur under a variety of conditions. Successful numerical simulation of the whole coal and gas outburst process provides the basis for identifying the outburst mechanisms, parameterizing the causative processes, and to defining potential precursors of failure.

Sulphate generation in South African underground and opencast collieries

Deterioration in the water quality results from coal mining, and the significant impact on the environment in South Africa has been reported (Funke in SA Water, Sci Technol 15:115–144; 1983). Pyrite in with South African coal can be oxidised to yield acidic and high salinity water. This study deals with the rate at which sulphate could be produced for collieries under different conditions. Four collieries in the Witbank coalfield were selected for this investigation. The boreholes were investigated with an in-situ multi-parameter probe, and then sampled at different times with a specific depth sampler to determine the chemical composition of the water in the collieries. Water level measurements and volumetric calculations were done to determine influx rates. Daily sulphate generation rate for underground mining was found to be in the range of 0.4–2.7 kg/ha, depending on the availability of oxygen and the residence time of the water (the time available for neutralising agents present to react) in the mining void. The exclusion of oxygen due to flooding and the presence of calcareous carbonates influences the observed sulphate generation.