Mining Safety and Sustainability I

Safety and sustainability are becoming ever bigger challenges for the mining industry with the increasing depth of mining. It is of great significance to reduce the disaster risk of mining accidents, enhance the safety of mining operations, and improve the efficiency and sustainability of development of mineral resource. This book provides a platform to present new research and recent advances in the safety and sustainability of mining. More specifically, Mining Safety and Sustainability presents recent theoretical and experimental studies with a focus on safety mining, green mining, intelligent mining and mines, sustainable development, risk management of mines, ecological restoration of mines, mining methods and technologies, and damage monitoring and prediction. It will be further helpful to provide theoretical support and technical support for guiding the normative, green, safe, and sustainable development of the mining industry

Green Low-Carbon Technology for Metalliferous Minerals

Metalliferous minerals play a central role in the global economy. They will continue to provide the raw materials we need for industrial processes. Significant challenges will likely emerge if the climate-driven green and low-carbon development transition of metalliferous mineral exploitation is not managed responsibly and sustainably. Green low-carbon technology is vital to promote the development of metalliferous mineral resources shifting from extensive and destructive mining to clean and energy-saving mining in future decades. Global mining scientists and engineers have conducted a lot of research in related fields, such as green mining, ecological mining, energy-saving mining, and mining solid waste recycling, and have achieved a great deal of innovative progress and achievements. This Special Issue intends to collect the latest developments in the green low-carbon mining field, written by well-known researchers who have contributed to the innovation of new technologies, process optimization methods, or energy-saving techniques in metalliferous minerals development

Design Programs for Highwall Mining Operations

Highwall mining is a hybrid of surface mining and underground mining methods, and is often the only feasible method to recover the coal reserves in the central Appalachian coalfields due to the steep terrain and the closely spaced multiple thin coal seams. Compared to the mountain-top-removal, contour, auger, and underground mining methods, application of the highwall mining method can reduce the environmental impacts, increase the recovery ratio of coal reserves, and enhance mine safety as well as productivity. Therefore, it is probable that highwall mining will be a dominant method for extracting the high-value coal resources in the Appalachian coalfields. By far, the greatest ground control safety concerns in highwall mining operations are rock falls from the highwall and mining equipment entrapment underground. These hazards are most likely caused by the instability of the highwall mine system due to insufficient mine design and difficulties encountered during mining operations.;Most of this thesis emphasizes the mine design concepts and methods to maintain the stability of mine structures. With the purpose of evaluating the stability of the entry roof, the beam theory is applied. After comparing the deflection, stress, and strain profiles of 0.05 ft sandstone and mudstone roof layers, it can be concluded that the existence of relatively thin and weak layer in the immediate roof could cause potential stability problems for the entry roof. Therefore, for highwall mining operations to be conducted in coal seams with thinly bedded roof strata, a correct decision to cut some of the thin weak roof rock layers with the main coal seam can be greatly beneficial to mining operations. The pressure arch concept is applied for the systematic design of the highwall mining operation. Within this concept, an optimization design process is developed to improve the recovery ratio of coal resources to a reasonably high level. For multi-seam highwall mining operations, the largest web and barrier pillar sizes should be selected and vertically aligned into seams. Two numerical programs, Examine2D and FLAC, are used to analyze the stability of highwall structures and to find the stable interburden thickness where no interaction between the two coal seams is expected. Numerical results show that, under given geology and mining conditions in the thesis, the stable interburden thickness is 20 ft and there are no stability issues. In the end, three spreadsheet programs are developed for the assessment of highwall mine structures, for the design of the web and barrier pillars, and for the optimization design process, based on the proposed design concepts and methodologies

Int J Min Sci Technol

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 longwall face. This paper describes recent research aimed at quantifying the effect of longwall-induced stress changes on ground stability and using the information to assess support alternatives. The research included monitoring of ground and support interaction at several operating longwall mines in the U.S., analysis and calibration of numerical models that adequately represent the bedded rock mass, and observation of the support systems and their response to changes in stress. The models were then used to investigate the impact of geology and stress conditions on ground deformation and support response for various depths of cover and geologic scenarios. The research results were summarized in two regression equations that can be used to estimate the likely roof deformation and height of roof yield due to longwall-induced stress changes. This information is then used to assess the ability of support systems to maintain the stability of the roof. The application of the method is demonstrated with a retrospective analysis of the support performance at an operating longwall mine that experienced a headgate roof fall. The method is shown to produce realistic estimates of gateroad entry stability and support performance, allowing alternative support systems to be assessed during the design and planning stage of longwall operations.CC999999/ImCDC/Intramural CDC HHSUnited States

Advances in Condition Monitoring, Optimization and Control for Complex Industrial Processes

The book documents 25 papers collected from the Special Issue “Advances in Condition Monitoring, Optimization and Control for Complex Industrial Processes”, highlighting recent research trends in complex industrial processes. The book aims to stimulate the research field and be of benefit to readers from both academic institutes and industrial sectors

Mining Technologies Innovative Development

The present book covers the main challenges, important for future prospects of subsoils extraction as a public effective and profitable business, as well as technologically advanced industry. In the near future, the mining industry must overcome the problems of structural changes in raw materials demand and raise the productivity up to the level of high-tech industries to maintain the profits. This means the formation of a comprehensive and integral response to such challenges as the need for innovative modernization of mining equipment and an increase in its reliability, the widespread introduction of Industry 4.0 technologies in the activities of mining enterprises, the transition to "green mining" and the improvement of labor safety and avoidance of man-made accidents. The answer to these challenges is impossible without involving a wide range of scientific community in the publication of research results and exchange of views and ideas. To solve the problem, this book combines the works of researchers from the world's leading centers of mining science on the development of mining machines and mechanical systems, surface and underground geotechnology, mineral processing, digital systems in mining, mine ventilation and labor protection, and geo-ecology. A special place among them is given to post-mining technologies research

A Model for Permeability Reduction in Polymer Nanocomposites and Its Experimental Validation

Environmental concerns have led to research interest in biodegradable plastics, especially polylactic acid (PLA). PLA, a bio-derived and biodegradable polymer which is readily available, is easy to process, and it can be a good substitute for conventional non-biodegradable polymers in food packaging applications. However, its poor gas barrier property has to be improved to make it competitive with more widely-used materials such as polyethylene terephthalate (PET) and polystyrene (PS). This can potentially be accomplished by dispersing nanoplatelets in the polymer as these additives act as impermeable barriers around which the diffusing molecules are forced to take a longer, tortuous path. The increased path length results in a reduction in the concentration gradient with a simultaneous reduction in the mass flux. A similar situation arises upon annealing the PLA which leads to the formation of crystals that again act as barriers to mass transfer. A combination of the two approaches may lead to further reductions in permeability.;To accomplish the goal of reducing permeability through PLA, an internal mixer was used to melt-mix nanoclay into the polymer matrix, and thin films were made using compression molding. Thermal measurements showed that these films were amorphous. Since the extent of hydrophobicity or hydrophilicity of the nanoclay surface influences the compatibility between the filler and the matrix, water vapor transmission rate experiments were conducted on nanocomposite films containing different commercially-available organically-modified nanoclays; a MOCON PERMATRAN W3/33 instrument was employed for this purpose. Based on the results obtained, it was found that Cloisite 30B was the most compatible clay with PLA. In other words, PLA containing Cloisite 30B had the largest reduction in water vapor permeability at a given clay loading level. Internal mixer operating conditions were then optimized to determine processing conditions that resulted in the best barrier properties for nanocomposite films made using Cloisite 30B. These were 200°C and 80 rpm for 5 mins. Under these conditions, it was found that, with an addition of 5.3 vol% (10 wt%) of Cloisite 30B, the water vapor permeability was reduced by 69% compared to neat PLA. The corresponding absolute value compares favorably to moisture permeability through PS. The solubility of moisture in the nanocomposites was measured in a separate set of experiments and was found to increase as the nanoclay loading increased. This was due to moisture adsorption on the nanofiller surface and not due to enhanced solubility within the polymer. Thus, the fractional reduction in water vapor diffusivity was the same as the fractional reduction in permeability.;The nanocomposite films were annealed to promote polymer crystallization, and the crystallinity level could be increased to 40% by annealing at 115°C for 40 hours. Under these conditions, the water vapor permeability was reduced by 45% compared to unannealed and unfilled PLA. When a nanocomposite film containing 2.6 vol% (5 wt) of Cloisite 30B was annealed under these same conditions, the water vapor permeability was reduced by a total of 66% compared to neat PLA. Annealed films containing more than 2.6 vol% clay were brittle, but the addition of acetyl butyl citrate (ATBC) which is a plasticizer enhanced ductility. When 5 wt% of ATBC was added to PLA, an annealed sample containing 5.3 vol% (10 wt%) of Cloisite 30B exhibited a 74% reduction in water vapor permeability compared to unannealed and unfilled PLA.;A new model that builds on the tortuous path concept was developed based on the reduction in both the mass flux and area for mass transfer when nanoplatelets are dispersed in a polymer matrix. According to this theory, the ratio of the permeability in the absence of filler to that in the presence of filler is given by (1 + [h/2t]&phis;) where h/t is the aspect ratio of the nanoplatelets, and &phis; is the filler volume fraction. When this theory was applied to moisture permeability results presented in this dissertation using an average aspect ratio determined from TEM pictures, there was quantitative agreement between the model prediction and the measured permeability value on PLA/clay nanocomposites at each filler loading level. By contrast, other theories available in the literature overpredicted the permeability values by a significant amount. Additionally, the theory predicts that the relative reduction in permeability is independent of the temperature of measurement and the concentration driving force, and this is again borne out by experimental results

Stochastic-optimization of equipment productivity in multi-seam formations

Short and long range planning and execution for multi-seam coal formations (MSFs) are challenging with complex extraction mechanisms. Stripping equipment selection and scheduling are functions of the physical dynamics of the mine and the operational mechanisms of its components, thus its productivity is dependent on these parameters. Previous research studies did not incorporate quantitative relationships between equipment productivities and extraction dynamics in MSFs. The intrinsic variability of excavation and spoiling dynamics must also form part of existing models. This research formulates quantitative relationships of equipment productivities using Branch-and-Bound algorithms and Lagrange Parameterization approaches. The stochastic processes are resolved via Monte Carlo/Latin Hypercube simulation techniques within @RISK framework. The model was presented with a bituminous coal mining case in the Appalachian field. The simulated results showed a 3.51% improvement in mining cost and 0.19% increment in net present value. A 76.95yd³ drop in productivity per unit change in cycle time was recorded for sub-optimal equipment schedules. The geologic variability and equipment operational parameters restricted any possible change in the cost function. A 50.3% chance of the mining cost increasing above its current value was driven by the volume of material re-handled with 0.52 regression coefficient. The study advances the optimization process in mine planning and scheduling algorithms, to efficiently capture future uncertainties surrounding multivariate random functions. The main novelty includes the application of stochastic-optimization procedures to improve equipment productivity in MSFs --Abstract, page iii

Stability Analysis of Bleeder Entries in Underground Coal Mines Using the Displacement-Discontinuity and Finite-Difference Programs

The stability of bleeder entries is essential for both mine ventilation and personnel travelling through the entries. Therefore, it is imperative that bleeder pillars remain stable and bleeder entries safe during their service life. Surprisingly, there are few published investigations on ground control issues in the bleeder entries. This thesis is an attempt to analyze the ground control problems in bleeder entries especially, the structural integrity of the bleeder entry. Two numerical programs (a) displacement discontinuity program-LaModel and (b) the finite difference program-FLAC were used to investigate these problems. Modeling results from the LaModel program indicated that the vertical stresses in bleeder pillars would first increase and then remain unchanged during retreat mining. The active longwall did not influence the stress concentrations and safety factors in the bleeder pillars of the adjacent mined-out panel in multiple longwall panels. The vertical stress concentration on bleeder pillars increased with depth. For detailed analysis of roof, pillar and floor of the mine entry simulation was performed in the finite difference program-FLAC. For realistic analysis, coal was assigned as strain-softening material and the gob was simulated with double yielding material. Results showed that the roof displacement in bleeder entries increased during second mining. The stability of the bleeder entry was affected by the behavior of the gob and active mining zone