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Copyright of Mining Report is the property of GVSt,GesamtverbandSteinkohlee.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Data on the parameters of explosion and detonation of two- and three-fuel mixtures of methane, coal dust, and hydrogen (with oxygen and air) with varied fractions of the fuels are reported. The novelty of the numerical and graphical data arrays is due to previously unknown data on the critical energy of detonation initiation, characteristic size of detonation cells, detonation velocity, and energy release in detonation waves. The analysis is performed not only for stoichiometric two- and three-fuel systems, but also for rich and lean systems based on the fuels under study. [ABSTRACT FROM AUTHOR]

The article focuses on official note from the Federal Chancellery/Foreign Affairs in Vienna, Austria on November 18, 1957. It mentions creation of an Austro-Hungarian Boundary commission for the regulation of border questions of replacement of damage caused by the erection of the Hungarian wire entanglement on Austrian territory. It also mentions vicinity of mine belt lying agricultural land, by violating Austrian citizens and the killing of domestic animals and by Hungarian mine explosions.

Detonation waves in gaseous two-fuel systems CH4/H2/O2 and heterogeneous three-fuel systems CH4/H2/O2/coal suspension are experimentally studied. The experiments are performed with coal particle sizes m and mean-volume densities of 160–400 g/m3. The velocities along the tube and the pressure profiles in incident detonation and reflected waves are measured. The influence of the fuel components on the wave parameters is analyzed. The experimental detonation parameters are compared with the predicted thermodynamic equilibrium detonation parameters. [ABSTRACT FROM AUTHOR]

In many regions of the world, mine activity accounts for the bulk of the total seismicity. Therefore, automatic identification of repeating mining events would significantly reduce the analyst’s workload at many seismological organizations. This work focuses on the problem of identifying mine blasts that originate from a specific mine, given a stream of seismic data. The mine pattern to identify is complex, as the mine spans several kilometers and the recorded blasts may be of a different type, magnitude, and location. Identification of such single blasts from ongoing recordings that contains diverse seismic events and noise is a challenging task, which is typically not executed in a fully automatic manner but is rather carried out by manual analysis. In this work, manifold learning techniques, which faithfully model high-dimensional data into a compact, low-dimensional space, are utilized. In particular, a modification of diffusion maps is applied for creating a compact representation of a large set of mine patterns, bypassing the need to select a representative subset of patterns. This representation is stable with respect to the changing time streams that hold new seismic data. In addition, manifold-based data fusion techniques are implemented for processing the three-channel seismic recordings. The capabilities of the model are presented on several different datasets and compared with deep learning techniques. The results highlight the method’s computational and explainable proprieties. [ABSTRACT FROM AUTHOR]

The combustion, explosion, and detonation in hybrid systems containing gas mixtures of CH4/air, CH4/O2, and O2/coal particles up to 200 μ m in size with a volume-averaged density of up to 700 g/m3 were studied on a vertical shock tube. X-ray diffraction patterns of the initial coal powder and coal samples subjected to high-temperature waves were analyzed. Data were obtained on the structure and parameters of waves in hybrid mixtures and in the same gas mixtures without coal dust. It is shown that in hybrid systems, coal dust has a weaker influence on the parameters of combustion and detonation waves than methane and that methane in these waves is more reactive than coal dust. [ABSTRACT FROM AUTHOR]

Mining activities are well known for being able to induce local seismicity but have not yet been shown to cause earthquakes over large distances. We analyze a particular group of seismic events recorded from 2014 to 2016 in north‐central British Columbia (BC) that appear to be triggered by the activities at the Mount Milligan Mine. The spatial distribution of the studied events follows a NW‐SE linear trend, with distances up to approximately 100 km from the mining site. To distinguish mining blasts from blasting‐related and natural events, we adopt a multivariate decision tree based on each event's origin time, distance from the mine, and the pseudo‐spectral acceleration ratios of the three‐component waveforms. The calculated dynamic strains from blasts place a distance limit of 20 km for dynamic triggering. However, accounting for the estimated epicentral uncertainty and temporal distribution of the earthquakes' origin times support the existence of blasting‐triggered events at larger distances (up to ∼50 km) from the mine, suggesting that a previously unmapped fault segment is close to critical state and may have been reactivated. The inferred fault segment aligns remarkably well with the southern extent of the Rocky Mountain Trench and may impose a significant hazard to nearby communities if the entire fault segment of about 150 km‐long ruptures. Key Points: Possibility of an event being triggered by blasts is determined by analyzing its spatio‐temporal occurrence and spectral characteristicsEpicenters of blasting‐induced events suggest the presence of an unmapped NW‐SE trending fault reactivated by repeating mining explosionsThe inferred fault segment, a split branch of the Rocky Mountain Trench fault system, can generate an earthquake of magnitude up to MW 7.6 [ABSTRACT FROM AUTHOR]

Background: On May 3, 2017, at 11:58 AM local time, an explosion occurred in the Zemestan- Yurt coal mine in Azadshahr City of Golestan Province, northern Iran, which resulted in mass casualty incident. Materials and Methods: In total, more than 126 miners were affected. Of them, 43 miners were killed, 73 other workers who helped their coworkers were also injured and taken to the hospital, and 10 injured people received on-site prehospital medical care. Many defects in the response phase were identified in the scene management and the triage. Results: It seems necessary to establish a response plan for mass casualty incident, hold regular education, and plan to prepare involved units for appropriate responses. Conclusion: These measures are the first steps needed to improve preparedness and response to a mass casualty incident. [ABSTRACT FROM AUTHOR]

Featured Application: The mobile robot described in the article is used for reconnaissance and inspection of underground coal mines after a catastrophic event. Knowledge from the article can be used as guidelines and aid for design of a mechatronic system with explosion safety for Group I (underground mines), Category M1 (presence of an explosive atmosphere). The article focuses on specific challenges of the design of a reconnaissance mobile robotic system aimed for inspection in underground coal mine areas after a catastrophic event. Systems that are designated for these conditions must meet specific standards and regulations. In this paper is discussed primarily the main conception of meeting explosion safety regulations of European Union 2014/34/EU (also called ATEX—from French "Appareils destinés à être utilisés en ATmosphères Explosives") for Group I (equipment intended for use in underground mines) and Category M1 (equipment designed for operation in the presence of an explosive atmosphere). An example of a practical solution is described on main subsystems of the mobile robot TeleRescuer—a teleoperated robot with autonomy functions, a sensory subsystem with multiple cameras, three-dimensional (3D) mapping and sensors for measurement of gas concentration, airflow, relative humidity, and temperatures. Explosion safety is ensured according to the Technical Report CLC/TR 60079-33 "s" by two main independent protections—mechanical protection (flameproof enclosure) and electrical protection (automatic methane detector that disconnects power when methane breaches the enclosure and gets inside the robot body). [ABSTRACT FROM AUTHOR]

Light armoured vehicles (LAVs) can be exposed to mine explosions despite the fact that they are generally not designed to withstand such loadings. The hull floor of LAVs is usually made of a plate only a few millimetres thin and is therefore a weak vehicle point in the case of blast loading. Therefore, blast resistance and the possibility of blast loads redirection are very important characteristics of LAVs in providing adequate protection. It is generally accepted that LAVs with shaped floors are more resistant to mine explosions, yet there is a lack of strong evidence of their blast protection mechanisms. This paper presents the results comparisons for VALUK 6 × 6 LAV with a flat hull floor and its modified V-hull floor version with a 90° angle in accordance with the 2b protection level of the NATO AEP-55 standard. For that purpose, combined Smooth Particle Hydrodynamics – Finite Element (SPH-FE) models were used. The results have shown that the V-hull floor offers a significantly improved vehicle response to blast loads. Blast waves are effectively dispersed and the local response of the vehicle is especially improved, which is very important when designing safe LAVs, as required by standard safety regulations. [ABSTRACT FROM AUTHOR]

Ground vibration is one of the environmental concerns caused by mine blasts. The signature-hole technique, essentially the convolution of a single-hole signature with an impulse train function representing the timing of the blast, is one method used to predict and control ground vibrations. This method requires measuring a signature waveform from a singular blasting hole, which may be a limitation. Deconvolution of vibration signals, the inverse problem of signature-hole method, is still a frontier issue to solve that limitation in mining engineering. Wiener filtering deconvolution is used to compress the impulse train into a time-lagged spike, so that a normalized single-hole signature can be extracted from the full blast vibration waveform. The proposed methodology gives good results for a case study of mining blast using electronic detonators. Successful deconvolution will eliminate the need for measuring signatures by using all the seismograph information collected routinely in mine operations. [ABSTRACT FROM AUTHOR]

This paper proposes a hybrid optimization method that combines the power of the harmony search (HS) with the mine blast algorithm (MBA). The resulting mine blast harmony search (MBHS) uses MBA for exploration and HS for exploitation. The HS is inspired by the improvisation process of musicians, while the MBA is derived based on explosion of landmines. The HS used in the hybrid algorithm is an improved version, introducing a new concept for the harmony memory size, while the MBA is modified in terms of its mathematical formulation. Several numerical problems and benchmarks with many design variables and constraints are used to validate MBHS, and the optimization results are compared with those from various algorithms in the literature. The numerical results show that the proposed hybrid method provides better exploitation ability (especially in the final iterations) and enjoys mature convergence to the optimum solution. [ABSTRACT FROM AUTHOR]

Precise prediction of blast-induced ground vibration is an essential task to reduce the environmental effects in the surface mines, civil and tunneling works. This research investigates the potential of imperialist competitive algorithm (ICA) in approximating ground vibration as a result of blasting at three quarry sites, namely Ulu Tiram, Pengerang and Masai in Malaysia. In ICA modeling, two forms of equations, namely power and quadratic, were developed. For comparison aims, several empirical models were also used. In order to develop the ICA and empirical models, maximum charge weight used per delay (W) and the distance between blasting sites and monitoring stations (D) were utilized as the independent variables, while, peak particle velocity (PPV), as a blast-induced ground vibration descriptor, was utilized as the dependent variable. Totally, 73 blasting events were monitored, and the values of W, D and PPV were carefully measured. Two statistical functions, i.e., root mean square error and coefficient of multiple determination (R2) were used to compare the performance capability of those prediction models. Simulation results show that the proposed ICA quadratic form can get more accurate predicting results than the ICA power form and empirical models. [ABSTRACT FROM AUTHOR]

Top stemming is necessary to stop the explosive energy from escaping through the upper part of blast-holes in cutting blasts of large-diameter deep-hole blasting in underground mines. The often-used single soil stemming frequently leads to material clogging which results in reduction of blasting efficiency. In this paper, a new water-soil composite stemming is proposed to solve the problem. A series of small-scale tests were conducted on solid concrete masonry blocks to investigate the effect of top stemming material and stemming length on blasting performance. The experimental results indicated that water stemming was worse at improving the utilization rate of the explosion energy compared with single soil stemming of the same length. Further, the mean fragment size decreased with the increase of stemming length for single water stemming. Three schemes of water-soil composite stemming were designed and the scheme with soil in the lower part and water filled in bags in the higher part had the best fragmentation. The water-soil composite stemming was applied in underground stopes, and field results indicated that the newly proposed stemming led to similar rock fragmentation with traditional single soil stemming, but greatly reduced the clogged blast hole ratio, thus effectively improving blasting and mining efficiency. [ABSTRACT FROM AUTHOR]

Coal and gas outbursts are a rapid and powerful energy-releasing process. The damage to coal and the release of gas in the initial stage play key roles in the occurrence of outbursts. Existing studies have mainly focused on the gas desorption processes in coal under specific conditions such as particle size, specified mass and exposure time of pulverized coal. However, these studies have focused less on the gas release during the initial stage, and the quantitative relationship between the outburst risk level and the test results. Seven coal samples with different metamorphic degrees were chosen for use in outburst simulation experiments to investigate trends in gas release from pulverized coal in the presence of N 2 and CO 2 . The results demonstrate a strong correlation between the gas release capacity during the first 10 s and natural desorption gas content of the onset of coal exposure during the first 120 min. In general, the higher the gas content, the larger the released gas volume, and thus the larger the limiting amount of desorptive gas. The gas release from an outburst coal sample is larger than that from a non-outburst coal sample within the first 10 s. There is a good linear relationship between the initial volume of released gas (in the first 10 s) and the initial expansion energy of released gas (IEERG), which can reflect the risk of coal outburst. Thus, according to the outburst critical value (42.98 mJ/g) of IEERG, the critical value of initial volume of released gas could be calculated to be 1.113 cm 3 /g. The results can provide a reference for further study of the effect of gas on outbursts and the investigation of coal and gas outbursts disasters. [ABSTRACT FROM AUTHOR]

Copyright of Scientific Bulletin of National Mining University is the property of National Mining University, State Higher Educational Institution and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article reports an investigation on the explosion characteristics of methane–coal dust hybrid mixtures in a ducted spherical vessel. Methane–coal dust hybrid mixture explosion can occur in coal mines and spread into mine tunnels. While investigating the effects of methane addition to coal dust–air mixtures, the violence of coal dust explosions was found to increase significantly in the presence of methane. The energy of ignition was found to impact on the pressure rises in the vessel and in the duct. The experimental data and scientific analysis presented can assist in addressing ducted explosions originating from hybrid mixtures in process industries such as coal mines. [ABSTRACT FROM AUTHOR]

Generally, there are two important types of microseismic (MS) signals caused by mining and blasting activities at coal mines. The waveform characteristics of MS signals using FFT, STA/LTA method, and envelope analysis were studied to distinguish these two types of MS signals. The main results are as follows: the dominant frequency and duration of two types of signals are significantly different. The following peak envelope curves of two types of MS signals fit a power function. The power exponent was obtained to describe the attenuated speed of the MS signals. The attenuation of the coal mining MS signals is slower and more fluctuant than that of the blasting signal. Waveform characteristics consisting of the dominant frequency, duration, and attenuation coefficient were extracted as the discriminating parameters. The discriminating performance of these parameters was compared and discussed. Based on the waveform characteristics, a discriminant model for coal mining MS and blasting signals was established by using Fisher linear discriminant method and its performance was checked. The results show that the accuracy of the discriminant model is more than 85%, which can meet the requirements of MS monitoring at coal mines. [ABSTRACT FROM AUTHOR]

Copyright of Scientific Bulletin of National Mining University is the property of National Mining University, State Higher Educational Institution and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article talks about the explosion that occurred at the Coal Glen coal mine in North Carolina on May 27, 1925 that killed everyone who was in the mine at the time. Topics discussed include mining started at Coal Glen in the 1850s, and mules that lived underground at the mine and were used to transport coal who also died in the explosion.

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. [ABSTRACT FROM AUTHOR]

As an explosion control measure, rock dusting has been used in underground coal mines in many major coal producing countries with different standards. The effectiveness of the rock dust in reducing explosion intensity has been proven by historic events and laboratory experiments. The main functions of rock dust in controlling mine explosions (i.e., isolator, physical heat sink and chemical energy absorber) have been quantitatively studied and results are presented in this paper. [ABSTRACT FROM AUTHOR]

As the mining depths increase, an increasing number of mines in China encounter a new type of integrated dynamic disaster of rockburst and water inrush, causing great casualties and economic losses. This occurs constantly due to lacking understanding of its occurrence mechanism. This study investigated the mechanism of rockburst and water inrush as a new type of integrated dynamic disaster that has occurred in several mining areas in China. Mechanism of rockburst and water inrush mutually induced was proposed. A theoretical formula for vertical stress and floor failure depth was established and the formula indicates that dynamic stress increase lead to the floor failure depth increase, meanwhile, the thickness of aquiclude decrease. Microseismic monitoring technology was used to examine the effect of dynamic stress induced by overlying strata movement on floor failure and the results showed that the depth of microseismic events in coal floor reached the maximum 28 m when the dynamic stress reached the maximum. The finite element method was used to verify the effect of dewatering on stress distribution and the displacement of surrounding rock, and the results indicated that dewatering leads to the formation of the overlying strata settlement, vertical stress decrease in the region above the area, and vertical stress increase in the boundary region of water-rich area. [ABSTRACT FROM AUTHOR]

Layering of methane in underground coal mines owing to poor ventilation leads to methane explosion hazard. We study the methane layering phenomenon and the effect of ventilation on dispersion of methane in underground coal mines at air velocities varying from 0.5 to 4.0 m/s. Three-dimensional simulations using CFD code ANSYS Fluent 12.0 were performed assuming the flow to be unsteady, turbulent and incompressible. The study demonstrated that ventilation significantly affects the behaviour of methane layering and dispersion of methane in underground coal mines. The layering length decreased with increase in air velocity. At air velocity of 4.0 m/s, the methane layering length considerably reduced to a safer level of about 1 m. Moreover, the simulation results showed a good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Theoretical analysis and laboratory tests were performed to investigate the fragmentation of rock-like materials under coupled static stress and spherical charge explosion. The variations of the explosion crater shape and volume were studied. The experimental results indicate that uniaxial static stress changes the shape of the explosion crater at the free surface from circular to elliptical and increases the volume of the explosion crater. In addition, a higher material strength corresponds to a smaller explosion crater volume. Under biaxial equal stress condition, the failure zone on the free surface is always circular and the volume of the explosion crater decreases and subsequently increases. The influence mechanisms of static stress on the explosion crater are discussed in detail, and the experimental phenomena are well explained. [ABSTRACT FROM AUTHOR]

Copyright of Archives of Mining Sciences is the property of Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

One of the most dangerous and most commonly present risks in hard coal mines is methane hazard. During exploitation by longwall system with caving, methane is emitted to mine heading from the mined coal and coal left in a pile. A large amount of methane also flows from neighboring seams through cracks and fissures formed in rock mass. In a case of accumulation of explosive methane concentration in goaf zone and with appropriate oxygen concentration and occurrence of initials (e.g. spark or endogenous fire), it may come to the explosion of this gas. In the paper there are presented results of numerical analysis of mixture of air and methane streams flow through the real heading system of a mine, characterized by high methane hazard. The aim of the studies was to analyze the ventilation system of considered heading system and determination of braking zones in goaf zone, in which dangerous and explosive concertation of methane can occur with sufficient oxygen concentration equal to at least 12%. Determination of position of these zones is necessary for the selection of appropriate parameters of the ventilation system to ensure safety of the crew. Analysis of the scale of methane hazard allows to select such a ventilation system of exploitation and neighboring headings that ensures chemical composition of mining atmosphere required by regulation, and required efficiency of methane drainage. The obtained results clearly show that numerical methods, combined with the results of tests in real conditions can be successfully used for the analysis of variants of processes related to ventilation of underground mining, and also in the analysis of emergency states. [ABSTRACT FROM AUTHOR]

Until 2008, the easternmost land borders of the European Union (Greek-Turkish land zone) were planted with minefields spanning 11 km. Therefore, numerous fatalities occurred in peacetime as migrants attempted to avoid Greek border checks. Numerous fatal incidents (51) were detected inside the Greek minefields between 1997 and 2008. Determination of age, sex, time of death, and nationality were evaluated in every case. The injuries' anatomical dispersion, their severity, and the mechanism of death were examined in relation to the victims' position at the moment of the explosion. Data research indicated that all victims were male, aged 18-30 in their majority, crossing border minefields mainly during the night. Their distance and position in relation to the point of detonation was a key factor in the trauma localization and severity. This review highlights the devastating consequences of the residual mines during peacetime, a situation that continues to be a persistent international problem. [ABSTRACT FROM AUTHOR]

Gas explosion is the most hazardous incident occurring in underground airways. Computational Fluid Dynamics (CFD) techniques are sophisticated in simulating explosions in confined spaces; specifically, when testing large-scale gaseous explosions, such as methane explosions in underground mines. The dimensions of a confined space where explosions could occur vary significantly. Thus, the scale effect on explosion parameters is worth investigating. In this paper, the impact of scaling on explosion overpressures is investigated by employing two scaling factors: The Gas-fill Length Scaling Factor (FLSF) and the Hydraulic Diameter Scaling Factor (HDSF). The combinations of eight FLSFs and five HDSFs will cover a wide range of space dimensions where flammable gas could accumulate. Experiments were also conducted to evaluate the selected numerical models. The Large Eddy Simulation turbulence model was selected because it shows accuracy compared to the widely used Reynolds' averaged models for the scenarios investigated in the experiments. Three major conclusions can be drawn: (1) The overpressure increases with both FLSF and HDSF within the deflagration regime; (2) In an explosion duct with a length to diameter ratio greater than 54, detonation is more likely to be triggered for a stoichiometric methane/air mixture; (3) Overpressure increases as an increment hydraulic diameter of a geometry within deflagration regime. A relative error of 7% is found when predicting blast peak overpressure for the base case compared to the experiment; a good agreement for the wave arrival time is also achieved. [ABSTRACT FROM AUTHOR]

The article analyzes the combat documentary film "The Battle of the Somme" shot by cinematographers Geoffrey H. Malins and John Benjamin McDowell. It focuses on the how the film was used by the British government for chalking out propaganda and also discusses its portrayal of the battle. It is noted that the film had an immense impact on the audience, especially the mine explosion scene. It states that the film still remains the most popular propaganda film in Great Britain.

According to the data analysis of the serious shortage to the production of mine rescue capsule, the transient response analysis of structures of mine rescue capsule. Analysis of the cabin window of different pressure and time under the condition of stress, strain, deformation and rebound situation. The calculation results show that the peak of 0.6 MPa, 1.2 MPa: two load, the maximum displacement observation window appears in the observation window lower position, respectively in 350 ms, 390 ms, 3.453 mm, 6.807 mm, reach. Check according to displacement nephogram, observation window parts in the shock wave; keep the overall coordination of deformation, the seal is still intact, relative displacement is approximately zero. Crest 0.6 MPa loading, observation window deformation value in the range of 0~3.453 mm, less than 10 mm, no local brittle fracture and crack. Crest 1.2 MPa loading, observation window deformation value in the range of 0~6.807 mm, less than 10 mm, no local brittle fracture and crack. Observation window meet the stiffness requirements. [ABSTRACT FROM AUTHOR]

A series of nanostructured La1-xNdxCo0.3Fe0.7O3 perovskite-type (x ranging from 0 to 1) were prepared using the co-precipitation method. CO gas sensing properties of La1-xNdxCo0.3Fe0.7O3 sensors were performed. La0.7Nd0.3Co0.3Fe0.7O3 sensor showed the highest response at 250 °C (S=52.8). [ABSTRACT FROM AUTHOR]