This paper presents the results of a unique study conducted by the National Institute for Occupational Safety and Health (NIOSH) from 2016 to 2019 to evaluate the effects of longwall-induced subsurface deformations on shale gas well casing integrity and underground miner safety and health. At both deep-cover and shallow-cover instrumentation sites, surface subsidence measurements, subsurface in-place

This paper presents a novel approach to investigate the relations between drilling signals and bit wear condition in real world full-scale mining operations. This research addresses the increasing demand for automation in mining to increase the efficiency, safety, and ability to work in harsh environments. A crucial issue in fully autonomous unmanned drilling is to have a system to detect the bit wear

The filtration and dewatering of fine clean coal not only ensure industrial water recycle in coal washing plant, but also reduce the moisture of coal product in order to meet the requirements of combustion or coking industry. Fine clean coal is mainly composed by organic matter, and the property difference of different organic matter determines the filtration and dewatering behavior. In this investigation

Coal mines are continuously seeking to determine the performance of entries with different ground control products and installation methods. There are many factors that impact how an entry will perform which include but are not limited to geology, overburden, bolting type and pattern, and mine design. At the National Institute for Occupational Safety and Health (NIOSH), research has been instituted

The flow of blasted ore during mining of moderately dipping medium-thick orebodies is a challenge. Selecting a suitable mining system for such ore bodies is difficult. This paper proposes a diamond layout sublevel open stoping system using fan blastholes with backfilling to mine such orebodies. To evaluate the performance of system the relationships between ore recovery and stope footwall dip angle

The Subtropolis Mine is a room-and-pillar mine extracting the Vanport limestone near Petersburg, Ohio, U.S. In February of 2018, mine management began implementing a heading re-orientation to better control the negative effects of excessive levels of horizontal stress. The conditions in the headings improved, but as expected, stress-related damage concentrated within crosscuts. The mine operator has

The effective reinforcement of two or more overlying layers of mine openings in a single installation is usually done by coupling of two standard rock bolts mainly during the extraction of medium-thick coal seams. However, field observations show that the couplers of multiple bolts often degrade or break mostly at their connections. These types of failures can be avoided by strengthening the couplers

Two miners were fatally injured when a pillar bump occurred during retreat mining in a southern West Virginia coal mine. The mine was operating in the Eagle seam with overmining in the No. 2 Gas and Powellton seams. A coal bump is defined as a sudden and violent failure of coal caused by the release of stored strain energy in the pillar. While significant strides have been made by academia, industry

Multiple seam interactions are a major source of ground instability in several U.S. coalfields. Empirical methods are well suited for this problem, because while the mechanics multiple seam interactions are very complex and poorly understood, many mining case histories are available for analysis. This study makes use of an updated database that includes 356 multiseam case histories, including 67 unsuccessful

In order to reach a large, untapped reserve of high-quality coal, D8 Cloverlick Mine proposed to mine a corridor nearly 600 m deep beneath the Benham Spur of Black Mountain, Kentucky’s highest peak. D8 Cloverlick Mine was extracting the Owl seam, but the corridor’s route lay approximately 20 m above century-old mine workings in the C–(Darby) seam. Adding to the concern, three serious coal bursts had

Longwall mining has existed in Utah for more than half a century. Much of this mining occurred at depths of cover that significantly exceed those encountered by most other US longwall operations. Deep cover causes high ground stress, which can combine with geology to create a coal burst hazard. Nearly every longwall mine operating within the Utah’s Book Cliffs coalfield has been affected by coal bursts

The exploitation of the underground is currently undergoing a major transformation process. Besides mining, alternative ways of utilization are playing an increasingly important role. These alternative utilizations include the storage of gases, the disposal of radioactive wastes, and the implementation of geothermal storage facilities. In addition, more and more mining operations are being shut down

A series of gas inrush events occurred during development at Grosvenor Mine resulting in exposure to elevated levels of methane at the production face. A total of 22 gas inrush events occurred, with between 15 and 130 m3 of methane released during each event. The presence of an undrained seam in the immediate floor, geotechnical characteristics of the floor, and the stress environment all contributed

Researchers from the National Institute for Occupational Safety and Health (NIOSH) are developing a coal pillar rib rating (CPRR) technique to measure the integrity of coal ribs. The CPRR characterizes the rib composition and evaluates its impact on the inherent stability of the coal ribs. The CPRR utilizes four parameters: rib homogeneity, bedding condition, face cleat orientation with respect to

Estimating the overall floor stability in a coal mine using deterministic methods which require complex engineering properties of floor strata is desirable, but generally it is impractical due to the difficulty of gathering essential input data. However, applying a quantitative methodology to describe floor quality with a single number provides a practical estimate for preliminary assessment of floor

Underground mine designs typically try to avoid extraction beneath streams and rivers of any significant size, especially when the overburden rock thickness between the stream bed and the mine is thin. Potential issues with mining beneath streams include excessive groundwater inflow to the mine, weak ground (roof, floor, and pillar) conditions, horizontal stress effects, as well as stream loss and

The National Institute for Occupational Safety and Health (NIOSH) conducted a comprehensive monitoring program in a room-and-pillar mine located in Southern Virginia. The deformation and the stress change in an instrumented pillar were monitored during the progress of pillar retreat mining at two sites of different geological conditions and depths of cover. The main objectives of the monitoring program

In the Kaiping Coal field, mining of five coal seams, located within 80 m in the Kailuan Group, #5, #7, #8, #9 and #12 coal seam, is difficult due to small interburden thickness, concentrated stress distributions, high coal seam metamorphism, and complex geological conditions. By using the ZTR12 geological penetration radar (GPR) survey combined with borehole observations, the overburden caving due

In order to ensure safe mining and reduce surface damage in shallow multi-seam mining, the failure characteristics of interburden strata with different coal pillars offset distances between pillars in the upper and lower seams, the distribution characteristics of stress concentration in coal pillars, and the development characteristics of stratum cracks and subsidence were investigated by physical

One of the most common critical areas of longwall mining in terms of ground stability are the gateroad and bleeder entries. These critical entries provide much-needed safe access for miners and allow for adequate ventilation required for dilution of hazardous airborne contaminants and must remain open during mining of a multi-panel district. This paper is focused on the stability of the longwall entries

Surface subsidence that results from longwall mining can be large magnitude and can affect significant areas. Conventional methods for subsidence monitoring include leveling, global positioning system (GPS), and photogrammetric surveys. Remote sensing techniques including, aerial LiDAR, terrestrial laser scanning, and satellite-based Differential Interferometric Synthetic Aperture Radar (DInSAR), are

This paper was developed as part of an effort by the National Institute for Occupational Safety and Health (NIOSH) to identify risk factors associated with bumps in the prevention of fatalities and accidents in highly stressed, bump-prone ground conditions. Changes of failure mechanism with increasing confinement, from extensional-to shear-dominated failure, are widely observed in the rupture of intact

Many states rely upon the Pennsylvania 1957 Gas Well Pillar Study to evaluate the coal barrier surrounding gas wells. The study included 77 gas well failure cases that occurred in the Pittsburgh and Freeport coal seams over a 25-year span. At the time, coal was mined using the room-and-pillar mining method with full or partial pillar recovery, and square or rectangle pillars surrounding the gas wells

Accurately estimating load distributions and ground responses around underground openings play a significant role in the safety of the operations in underground mines. Adequately designing pillars and other support measures relies highly on the accurate assessment of the loads that will be carried by them, as well as the load-bearing capacities of the supports. There are various methods that can be

Longwall gateroad entries are subject to changing horizontal and vertical stress induced by redistribution of loads around the extracted panel. The stress changes can result in significant deformation of the entries that may include roof sag, rib dilation, and floor heave. Mine operators install different types of supports to control the ground response and maintain safe access and ventilation of the

The spatiotemporal analysis of seismic zones characterised by the scattering and accumulation of strain energy in the roof-rocks of the excavated longwall panel where inelastic or elastic deformations occurred during hard coal seam mining is discussed. The studied longwall panel was designed to utilize the effect of partial stress relaxation caused by the earlier extraction of the coal seams located

This paper presents the development of an innovative standing support for underground mines. The main feature of this standing support is its exterior container, a combination of polyvinyl chloride (PVC) with large rupture strain and fibre-reinforced polymer (FRP) with high strength-to-weight ratio. To demonstrate the advantages of this cementitious grout filled PVC-FRP tubular (PFT) standing support

To study the seepage and deformation characteristics of coal at high temperatures, coal samples from six different regions were selected and subjected to computed tomography (CT) scanning studies. In conjunction with ANSYS software, 3D reconstruction of CT images was used for the establishment of fluid-solid conjugate heat transfer model and coal thermal deformation model based on the microstructures

In multi-seam mining, the interlayer rock strata between the upper coal seam (UCS) and the lower coal seam (LCS) appear damage and strength weakening after mining the UCS. Ground stability control of the gob-side entry retaining (GER) under the gob with close distance coal seams (CDCS) is faced with difficulties due to little attention to GER under this condition. This paper focuses on surrounding

This paper presents the results of numerical simulations carried out to confirm the influence of former mining activities on deformation of the mining terrain. The assessment of deformation changes was carried out with the use of FLAC3D program based on the finite difference method. Numerical calculations were carried out for the example of actual mining operations in seams 703/1–2 and 707/2 of “Marcel”

Gob ventilation boreholes (GVBs) are widely used for degasification in U.S. longwall coal mines. Depending on geological conditions, 30–50% of methane can be recovered from longwall gob using GVBs. A NIOSH funded research at the Colorado School of Mines confirmed that GVBs can efficiently reduce methane at the face. However, GVBs can also draw some fresh air from the face and create explosive gas zones

A surfactant-polyalkane system is investigated using chemical reagents to dissolve methane and control coal seam gas from low-energy, high-efficiency, safety, and environmental protection perspectives. At different temperatures and pressures, a high-temperature and high-pressure reactor, gas chromatograph, and other related experimental equipment were used to perform methane dissolution experiments

The study of flow behaviour of water-sand mixtures in fractured rocks is of great necessity to understand the producing mechanism and prevention of water inrush and sand gushing accidents. A self-developed seepage test system is used in this paper to conduct laboratory experiments in order to study the influence of the particle size distribution, the void ratio, and the initial mass of Aeolian sand

In the loose and fractured coal seam with particularly low uniaxial compressive strength (UCS), driving a roadway is extremely difficult as roof falling and wall spalling occur frequently. To address this issue, the jet grouting (JG) technique (high-pressure grout mixed with coal particles) was first introduced in this study to improve the self-supporting ability of coal mass. To evaluate the strength

Air leakage in underground coal mines presents a serious hazard for coal production and the safety of miners. Coating technology is commonly used as an efficient means for preventing air leakage. To address existing problems with high dust concentrations in large operations involving complex processes and the high cost of traditional coating technology, a novel coating technology that ensures intrinsic

For coal mines, rock, coal, and rock bolt are the critical constituent materials for surrounding rock in the underground engineering. The stability of the “rock-coal-bolt” (RCB) composite system is affected by the structure and fracture of the coal-rock mass. More rock bolts installed on the rock, more complex condition of the engineering stress environment will be (tensile-shear composite stress is

Here, the geological factors controlling deep geothermal anomalies in mines were studied based on the geotemperature, lithologic thermal conductivity, and related geological data collected from the Qianjiaying Mine, China. A simulation of the change in magma waste heat, conducted using the ANSYS Workbench, revealed the distribution characteristics of geothermal anomalies in this mine and the corresponding

In coal mining industry, with the depth growing of coal mines, the creep behaviours of coal and rock can extensively affect the mining safety, coalbed methane recovery and geo-sequestration. To acquire a better insight into their creep characteristics, an efficient and robust researching technique, nanoindentation, was applied to investigate the creep performances of coal and rock samples obtained

Severe gas disasters in deep mining areas are increasing, and traditional protective coal seam mining is facing significant challenges. This paper proposes an innovative technology using soft rock as the protective seam in the absence of an appropriate coal seam. Based on the geological engineering conditions of the new horizontal first mining area of Luling Coal Mine in Huaibei, China, the impacts

The present work aimed to study the effect of slurry conditioning on flocculant-aided filtration of coal tailings by the analysis of filtration kinetics and filter cake structure. Laboratory filtration tests of the coal tailings showed that both the shear rate and agitation time have significant effects on filtration rate and cake moisture. Moderate agitation at the shear rate of 92 s−1 was favorable

Underground gassy longwall mining goafs may suffer potential gas explosions during the mining process because of the irregularity of gas emissions in the goaf and poor ventilation of the working face, which are risks difficult to control. In this work, the 3235 working face of the Xutuan Colliery in Suzhou City, China, was researched as a case study. The effects of air quantity and gas emission on

The distribution characteristics and evolution law of rock mass fissures induced by mining are a key scientific issue in the study of deep rock mechanics. In this study, a series of uniaxial compression experiments was conducted on rock-like specimens containing double V-shaped prefabricated fissures at dip angles of α = β = 45°, α = 45°<β = 60°, α = β = 60°, and α = 60°<β = 75° with a rock mechanics

Accumulation of float coal dust (FCD) in underground mines is an explosion hazard that affects all underground coal mine workers. While this hazard is addressed by the application of rock dust, inadequate rock dusting practices can leave miners exposed to an explosion risk. Researchers at the National Institute for Occupational Safety and Health (NIOSH) have focused on developing a water curtain that

Coal seam gas content is frequently measured in quantity during underground coal mining operation and coalbed methane (CBM) exploration as a significant basic parameter. Due to the calculation error of lost gas and residual gas in the direct method, the efficiency and accuracy of the current methods are not inadequate to the large area multi-point measurement of coal seam gas content. This paper firstly

Digitalisation in mining refers to the use of computerised or digital devices or systems and digitised data that are to reduce costs, improve business productivity, and transform mining practices. However, it remains increasingly difficult for mining companies to decide which digital technologies are most relevant to their needs and individual mines. This paper provides an overview of digital technologies

Monitoring and assessment of underground climatic conditions are necessary to identify potential hazards and initiate remedial measures in advance that otherwise would lead to disastrous conditions. This paper discusses the concept of real-time monitoring and assessment of climatic conditions in a typical underground mine using sensors and GIS tools by utilizing a laboratory scale model. Typical ventilation

Directive (EU) 2017/164 establishes a fourth list of indicative occupational exposure limit values (IOELVs) to protect workers from risks of exposure to hazardous chemicals. It states that in underground mining and tunnelling, Member States may benefit from a transitional period regarding IOELVs for nitrogen monoxide, nitrogen dioxide, and carbon monoxide, during which the existing established IOELVs

It is pretty challenging and difficult to quantitatively evaluate the intensity of dynamic disasters in deep mining engineering. Based on the uniaxial loading-unloading experiments for five types of rocks, this paper investigated the energy evolution characteristics, and identified the damage and crack propagation thresholds. Also, the fragment size distributions of the rocks after failure were analyzed

Gas-solid fluidized bed separation is a highly efficient and clean technique for coal separation, and can effectively remove ash and sulfur contained gangue minerals from coal. However, the fine coal plugging distributor often leads to uneven fluidization and affects the separation effect. In this paper, different plugging ways were designed to study their effects on the fluidization characteristics

Underground mines in Arctic and Subarctic regions require the preheating of mine intake air during winter. The cold fresh air of those remote areas can be as severe as −40 °C and commonly needs to be heated to around +3 °C. This extensive amount of heating is usually provided by employing large-size air heaters, fueled by diesel, propane, natural gas, or heavy oil, leading to high energy costs and

With depletion of shallow deposits, the number of underground mines expected to reach more than 3 km depth during their lifetime is growing. Although surface cooling plants are mostly effective in mine air-conditioning, usually secondary cooling units are needed below 2 km depth. This need emerges due to the elevated thermal impacts caused by auto-compression of mine air as well as heat emissions from

An increase in methane, spontaneous fire and bumping hazards in Polish hard coal mines, observed in the last two decades, led to the need to elaborate the tools allowing proper selection of a range of preventive measures to fight them at the stage of designing coal extraction. Designing the production of a coal seams in the conditions of associated methane and spontaneous fires hazards in Polish hard

In this study, uniaxial compressive strength (UCS), unit weight (UW), Brazilian tensile strength (BTS), Schmidt hardness (SHH), Shore hardness (SSH), point load index (Is50) and P-wave velocity (Vp) properties were determined. To predict the UCS, simple regression (SRA), multiple regression (MRA), artificial neural network (ANN), adaptive neuro-fuzzy inference system (ANFIS) and genetic expression

In early 2018, the Boliden Garpenberg operation implemented an optimized control strategy as an addition to the existing ventilation on demand system. The purpose of the strategy is to further minimize energy use for main and booster fans, whilst also fulfilling airflow setpoints without violating constraints such as min/max differential pressure over fans and interaction of air between areas in mines

A complete thermodynamic model is described for temperature and heat flow distribution simulation for ventilation networks in underground mines. The method is called the Computational Energy Dynamics (CED) model of the heat, mass, and energy transport. The Thermal and Humidity (TH) transport elements of the full model are described for advection, convection, and accumulation, encompassing heat capacity

The fracture behaviour and crack propagation features of coal under coupled static-dynamic loading conditions are important when evaluating the dynamic failure of coal. In this study, coupled static-dynamic loading tests are conducted on Brazilian disc (BD) coal specimens using a modified split Hopkinson pressure bar (SHPB). The effects of the static axial pre-stress and loading rate on the dynamic

The Atkinson equation along with its friction factor is commonly used to estimate pressure requirement in mine ventilation. However, friction factor correlation of flow through broken rock, typically found in blasted stope, gob, rock pit or block caving rock deposits, etc., is currently unavailable. Also, it is impractical to conduct direct measurements of flow resistance in an inaccessible broken

Excessive exposure to heat can lead to injuries, illness, and death among mineworkers. The actual cost of heat-related injuries and illnesses is unknown because of underreporting and lack of symptom recognition. Multi-factorial, evidence-based, and field-ready guidelines for identifying–and predicting–physiological markers of heat strain are currently unavailable. The predicted heat strain (PHS) model

Researchers from the National Institute for Occupational Safety and Health (NIOSH) conducted a study in an isolated zone of an underground mine to characterize aerosols generated by: (1) a diesel-powered personnel carrier vehicle operated over a simulated light-duty cycle and (2) the simulated repair of existing equipment using manual metal arc welding (MMAW). Both the diesel-powered vehicle and MMAW

In 2012, the International Agency for Research on Cancer (IARC) classified diesel particulate matter (DPM) as a carcinogen to human. With the increased usage of diesel equipment in underground mines, miners have a high risk of over-exposure to DPM, which has drawn many concerns from the public. This study used computational fluid dynamics (CFD) to analyse the DPM dispersion and concentration distribution