As a prerequisite to producing super-clean coal with any physical coal cleaning process, such as microbubble flotation, the feed coal must be micronized to liberate the finely disseminated mineral matter. The stirred ball mill is regarded as one of the most efficient devices for micronizing coal. Using a five-inch batch mill, the optimum operating conditions have been determined in terms of media size, feed size, media type, stirring speed and percent solids. The rates of breakage determined with monosized feeds are compared on the basis of specific energy consumption. It has been found that a 20:1 ball size/particle size ratio gives optimum grinding conditions. With the fine particle sizes obtained using stirred ball milling, as well as other fine grinding techniques, a growing concern has been generated regarding the accuracy of these size distributions. An automated technique has been developed in which a complete mass balanced size distribution can be obtained using an Elzone® 80XY particle size analyzer. A computer program is used to blend the data from successively smaller Orifice tubes, as well as, to determine the weight percent of material in a particle size distribution finer than the lower detection limit of the analyzer. This result is then used to correct the distribution for the missing fine material. / Master of Science

Coal surface-mining is often implicated for its negative impacts on native flora and fauna. However, some studies suggest that, in reclaiming land after mining, there may be potential to create early successional habitat needed by many avian species currently in decline throughout eastern North America. I evaluated nest-site selection and nest success for on reclaimed mine lands in southwest Virginia during the summers of 2010 and 2011. For this nest-site analysis, I focused on 2 bird species common to reclaimed mine lands in southwest Virginia: field sparrows (Spizella pusillia) and indigo buntings (Passerina cyanea). In addition, I assessed bird community attributes in relation to various surface-mine reclamation regimens over a 5-year period from 2007-2011. For both species, I found estimates of daily nest success to be higher than other estimates reported in the literature; however, empirical estimates of adult and juvenile survival are needed to provide better estimates of population status. For field sparrows, models of avian nest success support the hypothesis that a tradeoff exists between nest concealment and a view of the surroundings for field sparrows. For indigo buntings, year explained the most variation in nest success, with much lower estimates of daily nest survival in 2010, possibly as a result of increased precipitation. I also assessed avian community dynamics in relation to vegetation changes on reclaimed mine sites and observed a total of 96 species throughout the 4 years of sampling. Local species persistence and species turnover were comparable to another continental scale study conducted using breeding bird survey (BBS) data. Observed changes in community vital rates were likely a result of changes in certain habitat attributes over the 5-year period. Lastly, seven species were unique to certain cover types, suggesting the need to consider landscape level processes when developing restoration guidelines for reclaimed coal surface-mines. / Master of Science

Respirable coal mine dust (RCMD) has long been recognized as an occupational health hazard. In addition to coal, RCMD can contain minerals such as crystalline silica (i.e., most often present as quartz). There has been a resurgence of lung diseases among US coal miners since the late-1990s which has emphasized the need for better quartz monitoring, and better dust characterization in general. Quartz monitoring in coal mines has traditionally used infrared (IR) spectroscopy-based analytical methods such as the MSHA Method P7 that require significant sample preparation and must be performed in a centralized lab. There are generally thus days to weeks between dust sample collection and reporting of results, which can prevent the prompt mitigation efforts to better control dust and reduce exposures. Recently, a rapid analysis method for quartz has been developed by the US National Institute for Occupational Safety and Health (NIOSH) using direct-on-filter (DOF) Fourier Transform Infrared (FTIR) spectroscopy. The method has been demonstrated in a number of NIOSH-led studies using both laboratory and field samples, and the results show very good accuracy relative to the Method P7 reference. However, it has heretofore not been widely used by others or compared to results from other non-IR analytical methods. Moreover, while FTIR can allow the measurement of additional analytes, this has not yet been a focus of DOF FTIR for RCMD analysis. Analytes such as kaolinite and calcite could be of particular interest in the context of RCMD source apportionment. In this thesis, the DOF FTIR method is used to estimate silica, kaolinite, and calcite mineral fraction in RCMD samples collected in 16 coal mines, and in the laboratory using dust source materials from those same mines. The results are compared to results from other dust characterization methods such as mass-based thermogravimetric analysis (TGA) and particle-based scanning electron microscopy with energy dispersive X-ray (SEM-EDX). Results indicate the usefulness of the DOF FTIR method, and comparison suggests the presence of significant non-carbonate minerals other than silica and kaolinite in the coal mine dust. The results also show that SEM-EDX frequently indicates more mineral content (primarily other aluminosilicates), than that is predicted by either FTIR or the TGA. Additionally, by focusing mainly on calcite (generally sourced from limestone-based rock dust used in coal mines to prevent coal dust explosion), the second part of this study explores basic source apportionment by analyzing mine samples and samples of major dust source materials (such as run-of-mine coal, rock strata, and rock dust products). Results show that calcite can serve as a suitable proxy for rock dust in coal mine dust, and the results are consistent with expectations surrounding the contribution of dust from different mine locations and sample sources. Additionally, the DOF FTIR also showed good agreement with the TGA and SEM-EDX. / Master of Science / Respirable dust generated in coal mines has long been recognized as an occupational health hazard. In addition to coal, coal mine dust can contain minerals such as crystalline silica, which is particularly hazardous. Since the mid-1990s, there has been an alarming and unexpected increase in lung diseases in coal miners. Respirable crystalline silica is assumed to be a likely causal factor for this resurgence of lung diseases, and this has emphasized the need for better respirable crystalline silica monitoring and to better understand coal mine dust composition. The standard method of measurement of silica (called the MSHA Method P7) generally takes days to weeks between dust sample collection and reporting of results, which can prevent the mine from taking prompt mitigative efforts to better control dust and reduce exposures. Recently, a rapid analysis method for silica has been developed by the US National Institute for Occupational Safety and Health (NIOSH) called the DOF FTIR (direct-on-filter Fourier Transform Infrared Spectroscopy). This method has been shown to have very good accuracy relative to the standard method (MSHA P7). However, it has heretofore not been widely used by others or compared to results from other analytical methods. Moreover, DOF FTIR can also be used to estimate other minerals of interest such as kaolinite and calcite, which can be important in the context of understanding coal mine dust sources. In this thesis, the DOF FTIR method is used to estimate silica, kaolinite, and calcite mineral fraction in coal mine dust samples collected in 16 coal mines, and in the laboratory using dust source materials from those same mines. The results are compared to results from other dust analysis methods such as mass-based TGA (thermogravimetric analysis) and particle-based SEM-EDX (scanning electron microscopy with energy dispersive X-ray). Results indicate the usefulness of the DOF FTIR method, and comparison suggests the presence of significant non-carbonate minerals other than silica and kaolinite in the coal mine dust. The results also show that SEM-EDX frequently indicates more mineral content than that is predicted by either FTIR or the TGA. Additionally, by focusing mainly on calcite—which is generally sourced from limestone-based rock dust used in coal mines to prevent coal dust explosion—the second part of this study explores the sources of the dust by analysing samples collected in mines, and samples generated in lab from major dust source materials (such as the raw coal, rock strata, and rock dust products obtained from the mines). Results show that calcite can be representative of rock dust in coal mine dust, and the results are consistent with expectations surrounding the contribution of dust from different mine locations and sample sources. Additionally, the DOF FTIR also showed good agreement with the TGA and SEM-EDX.

Enactment of regulatory standards for respirable coal mine dust (RCMD) concentration and crystalline silica content, and advancements in mine ventilation and dust controls led to a steady decline of occupational lung disease among US coal miners between the early 1970s and the mid-1990s. Since that time, there has been an alarming resurgence of disease especially in central Appalachia—with little hard data to pinpoint the causative factors in the mine environment. This situation has emphasized the knowledge gap surrounding specific dust characteristics and their sources. Key observations from many disease cases have suggested that dust constituents sourced from the rock strata in the mine (i.e., the rock layers that surround the target coal seam) may be particularly important; and this fits with the general tendency to extract thinner coal seams, and thus more rock, in many central Appalachian mines. To explore the characteristics of rock-strata sourced dust and its possible influence on the overall RCMD, this thesis reports two primary research efforts: Chapter 1 encompasses a case study conducted in an underground coal mine in West Virginia. (This chapter was previously published in the proceedings of the 18th North American Mine Ventilation Symposium, and is being reproduced with permission of the licensor through.) Following precedent from other studies, respirable dust samples were collected from key locations including in the intake airway, downwind an operating roof bolter, and adjacent to the feeder breaker. Additionally, three locations downwind the production face were simultaneously sampled during four individual continuous miner cuts—which was a unique feature of the current study. Dust was analyzed using previously established methods, including scanning electron microscopy with energy dispersive X-ray (SEM-EDX) to determine particle size and mineralogy distributions. Where comparable, results were generally consistent with those from other central Appalachian mines. However, the unique production sampling scheme offered new insights regarding the shift in particle characteristics as dust moves downwind from the generation point. Changes in size and mineralogy suggested that rock-strata sourced particles, especially aluminosilicates, might interfere with the SEM-EDX classification of other particles, especially coal. To explore the issue of aluminosilicate interference with coal classification, and the possible reasons, Chapter 2 covers two main lines of study. First, existing RCMD samples and SEM-EDX metadata were re-examined. Results suggested that particle loading effects could be at least partly responsible for the appearance of inordinately high aluminosilicate abundance (and conversely low coal) in some samples (i.e., the mineral particles might deposit on the sample filter in close proximity to the coal). Additionally, the presence of coal-mineral microagglomerates (MAGs) was demonstrated. The second line of study in Chapter 2 was therefore to explore whether MAG formation could be due to the RCMD generation process or environmental conditions—rather than merely an artifact of the sampling procedure—and the dispersibility of MAGs, which may have important implications with respect to dust exposure and biological response. Laboratory-generated samples collected passively demonstrated that coal-mineral MAGs can indeed occur without influence from typical RCMD sampling equipment. MAGs were significantly dispersed by sonication in deionized water, though gentle swirling did not yield consistent results. Moreover, in a surfactant solution that mimics natural lung fluid, MAGs were also dispersed. Compared to deionized water, the surfactant may promote more dispersion of coal particles in particular. / Master of Science / Occupational illnesses such as black lung in underground coal mining are still a worrisome issue in the industry. This research was aimed at gaining insight into rock-strata sourced dust and its possible influence on the overall characteristics of respirable coal mine dust (RCMD). The rock strata surrounding the coal seam is often rich in silicates and silica. A case study of RCMD was conducted in a thin-seam mine in West Virginia. Samples were collected in various locations and analyzed using electron microscopy among other methods. Results indicated that mineral dust, especially aluminosilicates, can be very abundant near the production face and might interfere with the measurement of coal dust. To explore such interference, a follow-up study was performed by revisiting a subset of RCMD samples examined in prior work. This approach yielded evidence of coal-mineral microagglomerates. Additional efforts in the laboratory recreated agglomerate formation and demonstrated their dispersibility. Results suggested that the occurrence of microagglomerates is not entirely a direct consequence of the sampling methodology and highlighted their potential importance within the context of exposure assessment and possible biological response.

The gasification of carbonaceous fuel materials offers significant potential for the production of both energy and chemical products. Advancement of gasification technologies may be expedited through the use of computational fluid dynamics, as virtual reactor design offers a low cost method for system prototyping. To that end, a series of numerical studies were conducted to identify a computational modeling strategy for the simulation of coal gasification in fluidized bed reactors. The efforts set forth by this work first involved the development of a validatable hydrodynamic modeling strategy for the simulation of sand and coal fluidization. Those fluidization models were then applied to systems at elevated temperatures and polydisperse systems that featured a complex material injection geometry, for which no experimental data exists. A method for establishing similitude between 2-D and 3-D multiphase systems that feature non-symmetric material injection were then delineated and numerically tested. Following the development of the hydrodynamic modeling strategy, simulations of coal gasification were conducted using three different chemistry models. Simulated results were compared to experimental outcomes in an effort to assess the validity of each gasification chemistry model. The chemistry model that exhibited the highest degree of agreement with the experimental findings was then further analyzed identify areas of potential improvement. / Ph. D. / Efficient utilization of coal is critical to ensuring stable domestic energy supplies while mitigating human impact on climate change. This idea may be realized through the use of gasification systems technologies. The design and planning of next-generation coal gasification reactors can benefit from the use of computational simulations to reduce both development time and cost. This treatise presents several studies where computational fluid dynamics was applied to the problem of coal gasification in a bubbling fluidized bed reactor with focuses on accurate tracking of solid material locations and modeling of chemical reactions.

Salinization of freshwaters by human activities is of growing concern globally. Salt pollution can cause adverse effects to aquatic biodiversity, ecosystem function, ecosystem services, and human health. In many regions of the world, and in coal-mining-influenced streams of the temperate forests of Appalachia USA, specific conductance (SC), a surrogate measure for the dissolved major ions composing salinity, has been linked to decreased diversity of benthic macroinvertebrates. However, assessments used to reach this conclusion have generally not accounted for temporal variability of salinity, as most studies use "snapshot" SC data collected concurrently with biological data at a single point in time. Effective management of salinization requires tools to accurately monitor and predict salinity while accounting for temporal variability. To improve those tools, I conducted analyses of 4.5 years of salinity and benthic macroinvertebrate data from 25 forested headwater streams spanning a gradient of salinity where non-salinity stressors were minimized. My objectives were to: 1) model the annual pattern of salinity, 2) determine if salinity measures derived from continuous data are more precise than snapshot SC as predictors of aquatic biology, and 3) quantify response to salinity of the benthic macroinvertebrate community. A sinusoidal model of the annual cycle of SC using daily measurements for 4.5 years revealed that salinity naturally deviated ± 20% from annual mean levels, with minimum SC occurring in late winter and maximum SC occurring in late summer. The pattern was responsive to seasonal dilution as driven by catchment evapotranspiration dynamics. Alternative discrete sampling intervals can approximate the pattern revealed by continuous SC data if sampling intervals are ≤ 30 days. Continuous SC variables did not significantly improve precision for prediction of benthic macroinvertebrate metrics (p > 0.1) as compared to snapshot SC using generalized additive mixed models. Results suggest that snapshot SC is a capable predictor of benthic macroinvertebrate community structure if sampling is carefully timed. However, continuous SC data can quantify chronic salt exposure, which supports a hypothesis to explain how temporal variability of field-based observations of salt sensitivity of benthic macroinvertebrate taxa may be influenced by life stage. Benthic macroinvertebrate community structure diverged from reference condition as salinity increased, with stronger relationships in Spring than in Fall. Intra-seasonal variation in community structure was also revealed across sampling dates. Non-Baetidae Ephemeroptera were most sensitive to salinity, with richness and abundance lower than reference at SC > 200 =µS/cm in Spring based on snapshot SC. Equivalent effects were predicted by mean monthly SC of 250-300 µS/cm from the prior Fall. Continuous conductivity monitoring may improve assessment of salinity effects because they can describe life-cycle exposure, which may aid investigations of mechanisms driving field-based observations of benthic-macroinvertebrate community alteration. / Ph. D. / Freshwater ecosystems around the world are at risk of contamination from salt pollution resulting from a variety of human activities. All natural freshwaters contain low levels of dissolved minerals, or salts, the combined concentration of which is referred to as salinity. Activities such as crop irrigation, road de-icing, and mining can cause salt pollution in streams and rivers, and excessive salinity can be toxic to many aquatic organisms. In many regions of the world, including in coal-mining-influenced streams of Appalachia USA, elevated salinity has been linked to decreased diversity of benthic macroinvertebrates, which are primarily aquatic insects, a group critical to healthy stream ecosystems. However, assessments used to reach this conclusion have generally not accounted for annual variability of salinity, as most studies use “snapshot” salinity data collected concurrently with biological data at a single point in time. Effective management of salinity impacts requires tools to accurately monitor and predict salinity while accounting for annual variability. Toward improving those tools, I conducted analyses of 4.5 years of salinity and aquatic insect data from 25 small central Appalachian mountain streams spanning a gradient of salinity. My objectives were to: 1) characterize the annual pattern of salinity using high-frequency salinity data, 2) determine if high-frequency salinity data is better than snapshot data for predicting aquatic insect diversity, and 3) measure the response to salinity of the aquatic insect community and identify salinity levels associated with insect biodiversity loss. High-frequency (daily) data revealed that salinity exhibited a predictable cyclic annual pattern with seasonal deviations of ± 20% from annual average salinity levels. Minimum salinity occurred during late winter and maximum salinity occurred in late summer. Lower-frequency salinity data can approximate the annual pattern if sampling interval is ≤ 30 days. Snapshot salinity was equally capable as high-frequency data of predicting aquatic insect diversity provided that snapshot salinity sampling is carefully timed. Diversity of many aquatic insects, especially mayflies, declined with increasing salinity, with stronger relationships in Spring than in Fall. Variation in diversity measures was also somewhat related to sample timing within seasons. Alteration of aquatic insect communities was evident at total salt concentrations levels of approximately 130 – 200 parts per million, depending on time of year. Efforts to manage salinity impacts to aquatic life may be improved by integrating knowledge of annual salinity patterns with how aquatic insects respond to salt pollution.

The Appalachian coal fields contain many contiguously placed seams of coal. Mining in these seams has been active over such an extended period of time that considerable knowledge has been gained in the area of multiple seam mining. It is commonly accepted that the preferred sequence of extracting contiguous seams is in descending order. However, in the past, selection of the mining sequence has been based primarily on seam ownership, availability and economics, not on ground control considerations. One of the major ground control mechanisms that must be considered in mine design, when contiguous seams have not been extracted in descending order, is subsidence. This investigation examines the affects of subsidence not on the surface but on mineable seams of coal lying above the seam that has been extracted. Case studies were collected from the Appalachian region. These studies were analyzed to determine which factors could be correlated with damage. An empirical model was then developed to predict when interaction problems caused by subsidence will noticeably effect mining in an upper seam. / M.S.

Dramatic changes in U.S. coal prices during the 1970's and 1980's have brought into question the ability of currently available forecasting models to predict non-renewable resource prices. This thesis compares two types of forecasting models used to predict non-renewable resource prices. Each model is assessed based upon theoretical and practical considerations. The models evaluated are a conventional time series model and an optimization model. The thesis finds each model to have inherent advantages and disadvantages within the areas of comparison. The conventional time series model is assessed as relatively simple to develop and easy to use for rough approximations of future prices, but lacking in its reflection of the current body of economic theory on non-renewable resources. The optimization model is evaluated as more thoroughly embracing some of the advances made in the theory, but requiring an extensive commitment of resources for its development. / Master of Arts

"Factors Which Affect Mining of the Lower Mississippian Coals in Montgomery County, Virginia" ie a study ot the Merrimac and Langhorne seams of the Price formation in Montgomery County, Virginia. The main reference used in the review of literature was Bulletin XXV of the Virginia Geolog1cal Survey by Marius R. Campbell. The review of literature discusses geologic formations and structure and the coal as seen in various prospect and mine openinga by Campbell. The author visited mines during the field investigation and analyzed samples of coal collected at the mines. He discusses past mining operations in Montgomery County and has traced all available mine maps of past mining operations. These are filed as part of the thesis. Core drillings were also investigated by the author and reported depths of the coal in the Blacksburg syncline ere entered in Table III and Figure I. An investigation was also made into mining methods used in Montgomery County including a discussion of explosive gases encountered in mining the Merrimac seam. The author discusses the results of the investigation in the conclusions. Be ia convinced the coals of the Valley fields, although of poor quality, will becane increasingly valuable as anthracite deposit in Pennsylvania and bituminous deposits in Southern West Virginia and southwest Virginia are depleted. / Master of Science

For a given coal gasification atmosphere, the reactions between fired alumina-chromia solid solution refractories and alkali (sodium and potassium) with and without sulfur at varying alkali concentrations were thermodynamically calculated using the SOLGASMIX-PV computer program and the results were experimentally confirmed. In addition, the kinetics of alkali diffusion into the refractory were experimentally determined as a function of time and temperature. The results, both experimental and theoretical, show formation of alkali-aluminate (Na₂O⋅Al₂O₃, K₂O⋅Al₂O₃) and β-alumina (Na₂O⋅11Al₂O₃, K₂O⋅11A₂O₃) compounds with formation of several metastable alkali compounds in a coal gasification environment. Sulfur did not appear to affect the reaction products. Alkali distribution into the alumina-chrome refractory is rapid and the formation of the Na₂O⋅Al₂O/K₂O⋅Al₂O₃ compounds cause large volume expansion from the reaction surface which causes poor thermal shock resistance and eventual refractory failure. The hot face of an alumina-chrome refractory in service in an alkali environment will be prone to failure by alkali attack. / Master of Science