A saúde e segurança do trabalhador em um empreendimento mineiro necessitam de atenções redobradas. O constante monitoramento dos agentes físicos e químicos, possivelmente danosos, deve ser feito para que seja demonstrada eficiência nas medidas preventivas e até mesmo para que novas situações de risco sejam detectadas. Este monitoramento deve ser feito por profissionais preparados, que podem ser os próprios funcionários da empresa, desde que devidamente capacitados. As informações necessárias para o treinamento desses profissionais encontram-se dispersas em diferentes literaturas. O objetivo deste trabalho é elaborar um guia unificado de procedimentos de amostragem e tratamento de dados por meio de descrição dos agentes, instrumentação utilizada e exemplos de medição de campo, com metodologias específicas. Os resultados obtidos foram tratados, analisados e comparados com a respectiva norma brasileira vigente. Foram considerados os principais agentes nocivos de uma pedreira: ruído, iluminação, sílica, vibração e calor que foram analisados com alguns dos diversos instrumentos disponíveis no mercado. Este guia, com as sugestões de monitoramento, pode ser aplicado a outros ambientes de mineração. Os resultados são parâmetros na elaboração de melhorias para a saúde e a segurança dos trabalhadores. / Health and safety of mining workers require extra attention. The continuous monitoring of physical and chemical agents, possibly harmful, is essential to verify the efficiency of preventive actions and to identify new risks situations. This job has to be carried out by qualified professionals that can even be the company\'s employees, since well trained. However, the required information for guidance is not easily found at the specific bibliographies. Thus, the goal of this work is to prepare a comprehensive guide of field measurements with some sampling tips, including the description of the physical and chemical agents, equipments examples, and the associated methodology. The results were analyzed and compared with the current Brazilian standards. This study considered the most harmful agents in a quarry: noise, illuminance, silica dust, human vibration and heat stress which were measured with some of the several equipments available in the market. This guide, with suggested monitoring practices, can be extended to other mining environments. The results were helpful in proposing enhancements to safety and health of miners.

A research report submitted to the faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering. / The theory of Mine Call Factor (MCF) compares the sum of metal produced in recovery plus residue to the metal called for by the mines evaluation method expressed as a percentage. This MCF concept is well known in underground scenarios and therefore this report highlights the MCF issues and the variable components affecting it from a surface mine perspective. The MCF investigation established the relationship between actual measurements and reporting against measurement protocols. Such measurements include “tonnage, volume, relative density, reconciliation strategy, and truck tonnage determination, sampling and assay standards. This study investigated how these measurements are conducted on Iduapriem Mine according to the mine’s standard operating procedures (SOP). An improvement of documents towards a metal accounting protocol based on the AMIRA protocol is recommended. The mine’s current quality control protocol was further expanded to reflect current practices. The mine to mill reconciliation compared production estimates from various sources (resource model, grade control model, pit design, plant and stockpile, truck tally, stockpile and plant feed, plant feed and plant received) in the period 2009 and 2010. Reconciliation factors expressed as a percentage were statistically analysed for discrepancies for tonnages and grades. It was realised that there is more confidence in mass (tonnage) measurement compared to grade. A generic mine to mill reconciliation path was suggested to be used by the mine.

The growing demand for ever more greener aero engines has led to ever more challenging designs and higher quality products. An investigation into Coordinate Measuring Machine measurement uncertainty using physical measurements and virtual simulations revealed that there were several factors that can affect the measurement uncertainty of a specific task. Measurement uncertainty can be affected by temperature, form error and measurement strategy as well as Coordinate Measuring Machine specification. Furthermore the sensitivity of circular features size and position varied, when applying different substitute geometry algorithms was demonstrated. The Least Squares Circle algorithm was found to be more stable when compared with the Maximum Inscribed Circle and the Minimum Circumscribed Circle. In all experiments it was found that the standard deviation when applying Least Squares Circle was of smaller magnitude but similar trends when compared with Maximum Inscribed Circle and the Minimum Circumscribed Circle. A Virtual Coordinate Measuring Machine was evaluated by simulating physical measurement scenarios of different artefacts and different features. The results revealed good correlation between physical measurements uncertainty results and the virtual simulations. A novel methodology for the automated assessment of leading edge airfoil profiles was developed by extracting the curvature of airfoil leading edge, and the method lead to a patent where undesirable features such as flats or rapid changes in curvature could be identified and sentenced. A software package named Blade Inspect was developed in conjunction with Aachen (Fraunhoufer) University for the automated assessment and integrated with a shop floor execution system in a pre-production facility. The software used a curvature tolerancing method to sentence the leading edge profiles which aimed at removing the subjectivity associated with the manual vision inspection method. Initial trials in the pre-production facility showed that the software could sentence 200 profiles in 5 minutes successfully. This resulted in a significant improvement over the current manual visual inspection method which required 3 hours to assess the same number of leading edge profiles.

With relatively high gravimetric and volumetric hydrogen storage capacities, borohydride compounds are being investigated for their potential use as hydrogen storage media. A study has been made into the mechanical milling of metal chlorides with sodium borohydride to try to form homoleptic borohydrides. Mechanical milling of zinc chloride with sodium borohydride resulted in the formation of a covalent complex NaZn\(_2\)(BH\(_4\))\(_5\). Thermal decomposition occurred at 80°C with a mass change of 12 wt.%, associated with the evolution of hydrogen and diborane. A composite mixture with magnesium hydride a reaction between diborane and magnesium hydride was observed form magnesium borohydride. Mechanical milling of calcium chloride or magnesium chloride with sodium borohydride did not produce calcium borohydride and magnesium borohydride, but rather resulted in solid solutions where chlorine ions substitute for borohydride ions within the cubic sodium borohydride lattice. Thermal decomposition of milled calcium chloride and sodium borohydride occurs at a similar manner to that of Ca(BH\(_4\))\(_2\) (from Sigma-Aldrich). Milled magnesium chloride and sodium borohydride thermally decomposes via several unknown phases with a weight loss of 4.4 wt.% yielding Mg, MgB\(_2\), B, and [B\(_{12}\)H\(_{12}\)]\(^{2-}\). Lithium borohydride investigated using Raman spectroscopy. After heating lithium borohydride through its orthorhombic to hexagonal phase change (118°C) and melting point (280°C), shifts in Raman peak position and peak width were measured as a function of temperature. This work shows the in-situ decomposition of LiBH\(_4\) observing formation of lithium dodecaborane (Li\(_2\)B\(_{12}\)H\(_{12}\)) at 340°C and amorphous boron from liquid lithium borohydride.

Spontaneous combustion of coal has historically been a major problem for the coal industry, predominantly during storage and transportation. Various methods have been used in the laboratory for evaluating the propensity of different coal sources to self-heat. However, the heterogeneity of coal and the complexity of the system has resulted in inconsistencies and sometimes conflicting results as indicated by the findings reported in several publications. The primary objective of the current study was to build a laboratory scale apparatus that simulates the condition of a coal stockpile to evaluate the events leading to spontaneous combustion and develop potential remedies. As such, the influential factors can be identified with confidence, thereby providing an improved understanding of the spontaneous combustion. An adiabatic heating apparatus was designed and constructed which included instrumentation to closely monitor the oxidation process and the stages leading to spontaneous combustion under various conditions. The device was equipped with thermocouples which measured the temperature rise as a function of time leading to the determination of an index value that indicated the propensity of a given coal source to spontaneously combustion. The index was referred to as the R70 value which was measured as the temperature was increased during the period of rapid oxidation. The units for the index was degrees Celsius per hour. As such, a high index value reflected the likelihood of spontaneous combustion for a given coal source. To standardize the test procedure, a detailed three-level statistical experimental design was conducted involving three critical parameters, i.e., particle size, oxygen flow rate and the duration of the drying period prior to feeding oxygen to the system. Using empirical models describing the R70 value as a function of the parameter values developed from the test data, it was determined that R70 was sensitive to the sample particle size and drying time. A decrease in particle size and drying time significantly increased the R70 value while the oxygen rate did not have a significant impact over the range of values tested. Based on the results of the test program, a standard test procedure was established to evaluate various coal sources and identify chemicals that could be used to remediate the spontaneous combustion issue. Several sub-bituminous coal sources collected from the Powder River Basin were tested in the apparatus and found to be prone to spontaneous combustion as indicated by R70 values that approached 50oC per hour. Several chemicals were evaluated as a means of eliminating or slowing the spontaneous combustion process. These agents included anti-oxidants, binders and humectants. Organic binders were used to agglomerate the fine coal particles which limited surface area exposure. The effect significantly reduced the oxidation rate as indicated by a reduction in the R70 index from 44.07oC/hr to 5.71oC/hr. However, after entering the latent heat stage, the temperature increased rapidly at a rate of 27.58oC/hr. Humectants were evaluated which contained several hydrophilic groups, mainly hydroxyl groups, and thus have an affinity for water. As a result, when the coals were treated with humectant, the latent heat rate was reduced to 4.24oC/hr although the R70 remained relatively high. By using a combination of humectant and binder, the optimum result was obtained with an R70 value of 5.04oC/hr and a latent heat rate of 11.06oC/hr. These findings were successfully implemented into industrial practice for significantly delaying the spontaneous combustion event.

Dust generation at an underground coal mine working face continues to be a health and safety issue. Prolonged exposure to high concentrations of airborne respirable dust can cause a debilitating and often fatal respiratory disease called Black Lung. In addition, the deposition of float dust in mine return airways poses a serious safety hazard if not sufficiently diluted with inert rock dust. A localized methane explosion can transition into a self-propagating dust explosion. Since dust is a byproduct of various mining activities, such as cutting and loading, crushing, and transportation, the dust-related issues cannot be totally eliminated. However, the adverse health effects and safety concerns can be minimized if a significant amount of the generated dust is removed from the ventilation air by a mechanical device, such as a dust scrubber. Over the last three decades, flooded-bed dust scrubbers integrated into continuous miners have been successfully applied for capturing and removing airborne dust generated at the working face. According to the National Institute for Occupational Safety and Health (NIOSH), a flooded-bed scrubber can achieve more than 90% capture and cleaning efficiencies under optimum conditions. Although flooded-bed scrubbers have proven useful in the vast majority of cases, they have not yet been successfully applied to a longwall face. In the United States, numerous attempts have been made to reduce dust concentration at a longwall face through the application of a scrubber; but, none were successfully implemented. Encouraged by the successful use of a flooded-bed scrubber system at continuous miner faces, this research revisits the flooded-bed scrubber concept for a longwall shearer. For this investigation, a full-scale physical model of a Joy 7LS longwall shearer, modified with an integrated flooded-bed dust scrubber, was designed and fabricated at the University of Kentucky. The scope of work for this research was limited to capturing and cleaning dust generated near the shearer headgate drum only. The mock-up was transported to, and assembled in, the full-scale longwall dust gallery at the NIOSH Pittsburgh Research Laboratory (PRL). Tests were conducted to examine: (1) the effect of the scrubber on headgate-drum dust reduction and (2) the combined effect of the scrubber and splitter sprays on headgate drum dust reduction. Analysis of test results for the scrubber-alone condition indicates a significant dust reduction of up to 57% in the return airway and 85% in the test gallery walkway, whereas the combination of scrubber and splitter-arm sprays shows dust reduction of up to 61% and 96% in the return and walkway, respectively. These results indicate that a flooded-bed scrubber integrated into a longwall shearer can be used as a viable technique to reduce a large portion of airborne dust at a longwall face. Subsequently, a Computational Fluid Dynamics (CFD) model of the longwall gallery and shearer was developed and validated using the results of the experimental study. The CFD simulation results are in good agreement with the experimental results with a maximum of 9.7% variation. This validated CFD model can be used in future research to predict the effects of modifications to the scrubber system, including modifications to the scrubber inlet, to optimize the scrubber design, and to evaluate the effectiveness of adding a tailgate drum dust scrubber.

In mining engineering, blast-induced ground vibration has become one of the major concerns when production blasts are conducted, especially when the mining areas and the blast sites are near inhabited areas or infrastructure of interest. To comply with regulations, a vibration monitoring program should be developed for each mining operation. The vibration level, which is usually indicated by the peak particle velocity (PPV) of the vibration waveform, should fall below the maximum allowable values. Ideally, when blasting is near structures of interest (power towers, dams, houses, etc.), the vibration level (PPV) should be predicted prior to the actual production blasts. There are different techniques to predict the PPV, one in particular is the signature hole technique. This technique is based on signals and systems theory and uses a mathematical operation called convolution to assess the waveform of the production blast. This technique uses both the vibration waveform of an isolated hole and the timing function given by the timing used in the blast. The signature hole technique requires an isolated single-hole waveform to create a prediction. Sometimes this information is difficult to acquire, as it requires the synthesis of a single-hole vibration waveform from a production blast vibration signal. The topic of ground vibrations from mining blasts, and more specifically the synthesis of a single-hole vibration waveform, has been studied by researchers in past decades, but without any concrete success. This lack of success may be partially due to the complexity and difficulty of modelling and calculation. However, this inverse methodology can be very meaningful if successfully applied in blasting engineering. It provides a convenient and economical way to obtain the single-hole vibration waveform and make the prediction of a production blast waveform easier. This dissertation research involves the theories of deconvolution, linear superposition, and Fourier phases to recover single-hole vibration waveforms from a production waveform. Preliminary studies of deconvolution included spectral division deconvolution and Wiener filtering deconvolution. In addition to the adaptation of such methodologies to the blast vibrations problems, the effectiveness of the two deconvolution methods by the influence of delay interval and number of holes is also discussed. Additionally, a new statistical waveform synthesis method based on the theories of linear superposition, properties of Fourier phase, and group delays was developed. The validation of the proposed methodology was also conducted through several field blasting tests. Instead of synthesizing one normalized single-hole vibration waveform by deconvolution, the proposed statistical waveform synthesis methodology generates a different single-hole vibration waveform for each blast hole. This method is more effective and adaptable when synthesizing single-hole vibration waveforms. Recommendations for future work is also provided to improve the methodology and to study other inverse problems of blast vibrations.

The following dissertation introduces the hazard of methane buildup in the gob zone, a caved region behind a retreating longwall face. This region serves as a reservoir for methane that can bleed into the mine workings. As this methane mixes with air delivered to the longwall panel, explosive concentrations of methane will be reached. Computational fluid dynamics (CFD) is one of the many approaches to study the gob environment. Several studies in the past have researched this topic and a general approach has been developed that addresses much of the complexity of the problem. The topic of research herein presents an improvement to the method developed by others. This dissertation details a multi-scale approach that includes the entire mine ventilation network in the computational domain. This allows one to describe these transient, difficult to describe boundaries. The gob region was represented in a conventional CFD model using techniques consistent with past efforts. The boundary conditions, however, were cross coupled with a transient network model of the balance of the ventilation airways. This allows the simulation of complex, time dependent boundary conditions for the model of the gob, including the influence of the mine ventilation system (MVS). The scenario modeled in this dissertation was a property in south western Pennsylvania, working in the Pittsburgh seam. A calibrated ventilation model was available as a result of a ventilation survey and tracer gas study conducted by NIOSH. The permeability distribution within the gob was based upon FLAC3d modeling results drawn from the literature. Using the multi-scale approach, a total of 22 kilometers of entryway were included in the computational domain, in addition to the three dimensional model of the gob. The steady state solution to the problem, modeling using this multi-scale approach, was validated against the results from the calibrated ventilation model. Close agreement between the two models was observed, with an average percent difference of less than two percent observed at points scattered throughout the MVS. Transient scenarios, including roof falls at key points in the MVS, were modeling to illustrate the impact on the gob environment.

The demand for rare earth elements (REEs) has increased over the last decade due to applications in high technology devices including those in the defense industry. The recovery of REEs from primary sources such as rare earth minerals are viable using physical separations followed by chemical processing. However, weak market values and environmental concerns have limited the viability of such operations. On the other hand, REE recovery from secondary sources such as apatite ore, bauxite waste, and waste recycling, provides an opportunity to take advantage of a resource that does not require mining costs as well as other associated costs given that these expenses are covered by the revenue generated from the production of the primary material. Coal-based materials represent a potential source for REEs which may be extracted and concentrated by the use of physical and/or chemical processes. The current study focused on developing a leaching process to extract REEs from the pre-combustion coal sources including coarse and fine refuse and low-valued material obtained from coal preparation plants. Materials collected for leaching characteristic studies were found to have average total REE concentrations in the range of 200-350 ppm on a whole sample basis. Mineralogy studies performed on Fire Clay seam coal refuse using SEM-EDS detected micro-dispersed rare earth phosphate mineral particles which are generally difficult to dissolve in strong acid solutions. On the other hand, XRD analysis results from a high REE content segment of the West Kentucky No. 13 coal seam indicated the presence of fluorapatite which is soluble in weak acid solutions. The mineral associations of REEs were studied by extracting REEs using different types of acids under various pH conditions. Differential extraction of the REEs was examined along with the associated impurity elements such as iron, aluminum, and calcium among others. The findings showed that the light REEs were primarily associated in a phosphate mineral form, whereas the heavy REEs were mostly present in an ion substitution form associated with clay minerals. Relatively high concentrations of REEs were discovered in mixed-phase particles consisting of both coal and mineral matter. By reducing the particle size, more leachable forms of REEs were liberated and recovered along with the associated mineral matter embedded in the coal structure. The type of lixiviant played an important role during the initial stage of leaching but was found to be insignificant as the system reached equilibrium. Solids concentration in the leaching medium has an important role in establishing the throughput capacity of the leaching system. Test results found that an increase in solids concentration had a significant negative effect on rare earth recovery. This finding may be explained by higher concentrations of soluble calcium-based minerals such as calcite which provided localized pH increases near and within the pores of the solids. The result was precipitation of CaSO4 within the pores which blocked access for the lixiviants. This hypothesis was supported by the findings from BET and XPS analyses which found lower pore volume in high solid concentration systems and the existence of CaSO4 on the surface of the solids. Leaching test results obtained using sulfuric acid over a range of temperatures showed that the leaching process was mainly driven by a diffusion control process. The activation energy determined for an Illinois No. 6 coal source was 14.6 kJ/mol at the beginning of the reaction and 35.9 kJ/mol for the rest of the leaching process up to 2 hours. For material collected from the Fire Clay coal seam, the apparent activation energy was 36 kJ/mol at the start of the leaching reaction and decreased to 27 kJ/mol over the remaining period of the test. The activation energy values were nearly equivalent to the upper-level values that generally define a diffusion control process and the lower values of a chemical reaction control process. The lack of clarity in defining a clear control mechanism is likely associated with the variability in associated mineralogy, various modes of occurrence of the REEs and the interfacial transfer of product through the porous structure of the coal-based particles which requires relatively high activation energy. As such, both diffusion control and chemical reaction control mechanisms are likely occurring simultaneously during the leaching process with diffusion control being more dominant.

Utilizing data collected by the University of Kentucky Lung Cancer Research Initiative (LCRI), this study investigated potential mining-related sources for the elevated levels of cadmium in Harlan and Letcher counties. Statistical analyses for this study were conducted utilizing SAS. A number of linear regression models and logarithmic models were used to evaluate the significance of the data. The linear regression models consisted of both simple and multivariate types, with the simple models seeking to establish significance between the potential sources and urine cadmium levels and the multivariate models seeking both to identify any statistically significant linear relationships between source types as well as establish a relationship between the potential source and the urine cadmium levels. The analysis began by investigating which ingestion method caused the increased levels of cadmium exposure. The analysis included ingestion through water sources and inhalation of dust. Of these two, dust showed the higher level of correlation. The second step was to analyze a number of sources of dust, particularly those related to mining practices in the area. These included the proximity to the Extended Haul Road System, secondary haul roads, rail roads, and processing plants. Of the variables in the analysis, Extended Haul Roads, secondary haul roads, and rail roads showed no correlation, and only the proximity to processing plants showed statistical significance.