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By M. Scaggs, K. Phillips

"Coal Worker’s Pneumoconiosis (CWP) is an occupational lung disease caused by chronic exposure to respirable mine dust. After decades of steady decline, CWP incidence appears to be on the rise since the mid-1990s, particularly in some regions of Appalachia. Alarmingly, many of these cases have rapidly progressed to the most advanced form of CWP, referred to as Progressive Massive Fibrosis (PMF). Most of what is currently understood about respirable mine dust has been gleaned from routine regulatory monitoring, which tracks total mass concentration of respirable dust (mg/m3) and, less frequently, silica mass content. This paper focuses on the use of thermogravimetric analysis (TGA) as a way to provide basic characterization of the whole composition of the dust, allowing it to be classified into three mass fractions – coal, carbonate, and non-carbonate minerals. TGA was conducted on 59 dust samples collected by miners from eight coal mines in central Appalachia, and the results are discussed in terms of differences between mines, regions, and primary occupations. Consistent with prior results on area dust samples from some of the same mines, results of the personal samples generally show that the coal mass fraction of the dust is relatively low. Carbonate and non-carbonate minerals thus tend to make up the bulk of the dust mass, and vary across occupations and specific mines. INTRODUCTION After nearly four decades of decline, the prevalence of Coal Workers’ Pneumoconiosis (CWP, or “black lung”) in the US has been on the rise since the mid-1990s (Laney et al., 2014; Laney et al., 2010; Suarthana et al., 2011; Pollock et al., 2010; Antao et al., 2005; Blackley et al., 2016). Particularly alarming is the number of cases of progressive massive fibrosis (PMF), which is the most advanced form of the disease (Pollock et al., 2010; Antao et al., 2005; Blackley et al., 2016; Laney et al., 2017). A recent study by Laney et al. (2017) observed 192 US coal miners participating in the Coal Workers’ Health Surveillance Program (CWHSP) who had been diagnosed with PMF since 2000. Of the 163 (85%) that had a normal radiograph on file to use as a baseline, 27 (17%) of these individuals had progressed from a normal radiograph to PMF diagnosis in less than 10 years. Moreover, 162 (84%) of the individuals in that study worked in KY, WV or VA, and 169 (88%) had only ever mined underground. Blackley et al. (2016) also reported on a group of 60 PMF cases that were discovered by a single black lung clinic in eastern KY. Since seeking care at such clinics and participation in the CWHSP are voluntary, and could be influenced by a number of factors, these recent reports may well overestimate the degree of resurgence in severe disease (i.e., versus disease that was previously under-reported). Even so, they highlight a critical need to better understand the cause(s) of disease development and progression – such that effective interventions can be devised."

Jan 1, 2018

By Gerald Verbeek, Erick Baziw

Stone columns are used in geotechnical site remediation to increase load-bearing capacity and reduce settlement of foundations. Stone columns also improve slope stability and increase the shear strength of a soil. A very challenging problem is to characterize the in-situ shear wave velocities from data acquired from Downhole Seismic Testing (DST) after the insertion of stone columns. DST is an important geotechnical testing tool for site characterization that provides low strain (<10-5) in-situ interval compression and shear wave velocity estimates, but the postanalysis of seismic data acquired from DST in the presence of stone columns is very challenging due to the resulting complicated in-situ soil conditions. To obtain the right results it is necessary to use an algorithm that incorporates source wave raypath refraction. Starting with the Normal Moveout Seismic Cone Tomographic Testing (NMO-SCTT) algorithm developed some years ago, this paper outlines the modifications and additions made to this NMO-SCTT algorithm to facilitate stone column site characterization. To dramatically reduce the optimal solution space for the estimated interval velocities the paper also described a priori conditions that are applied based on the unique nature of the stone column site conditions.

By L. T. Pasiechnyk

After a brief review of the various hydrocarbon storage methods currently being utilized and statistics on underground hydrocarbon storage, this paper will briefly describe the technology involved in solution mining salt to create caverns of engineered shape and size and briefly discuss the economical and environmental advantages of hydrocarbon storage in solution-mined salt caverns. Other possible uses of salt caverns will be mentioned.

Jan 1, 1978

By E. J. Gleim

Contact with trolley wire in the mines of the United States has taken a considerable toll of life throughout the years that trolley locomotives have been employed as a means of&apos; transportation. A study3/ of the records over a 15-year period for one State alone showed that, of 98 fatalities resulting from contacts with electrical circuits and equipment, 75 were caused by direct or indirect contact with unguarded trolley wire in coal mines. The law relating to guarding trolley wires in the mines of this particular State, as amended in 1935, reads in part as follows: "All trolley wires carrying 220 volts or more, and less than six feet six inches above top of rail, must be guarded at all points under which men and animals are required to pass***,&apos;" The natural conclusion to be drawn from such records is that lack&apos; of guards or shields must be held responsible for these fatalities. As a preventive measure, it has been advocated that every foot of trolley wire in mines should be guarded. Although some such drastic steps may appear to be amply justified, closer examination of the records nor this and other coal-mining States shows that absence of guards is not entirely responsible; but rather that other factors, such as carelessness and neglect it the observance of certain well-established simple rules concerning installation and location of trolley wires, also are responsible. In other words, if trolley wire is installed carelessly and its maintenance is neglected, it should not be expected that the mere installation of guards will overcome such carelessness and neglect. This publication discusses Various types of guards that have been used in Coal and metal mines of this country, together with related steps bearing upon the problem of &apos;preventing shock and fatalities from contacts with trolley wire. The material herein contained is taken largely from Information Circular 6577,4/ now out of print, and has been revised to include some types of guards that have been used in metal mines, together with a discussion of guard materials not covered in that publication.

Jan 1, 1945

By J. `. Spitzinger

In situ recovery (ISR) of uranium alters the baseline groundwater geochemistry in order to mobilize and complex uranium to extract and concentrate it. ISR wellfield restoration is often challenging, and primarily relies on groundwater sweep, reinjection of treated permeate, and/or injection of reductants. Greater focus should be placed on injection-based approaches (using existing infrastructure) based on established engineering concepts used for in situ remediation of groundwater plumes. Such injection-based approaches could shorten restoration timeframes consequently reducing long-term operational costs. This paper addresses various types of injection-based approaches to wellfield restoration based on in-situ remediation success with other constituents that require similar treatment. This paper describes necessary design practices for injecting reactive chemicals (e.g., reductants or biostimulants), operations and maintenance (O&M) strategies to prevent fouling of the chemical delivery system and well network, and natural constraints to restoration. Best practices for successful biostimulation strategies that minimize residual uranium, radium, oxoanions, and other trace elements are as described. Advantages of such injection-based approaches could include significant reductions in restoration times, and consequently, lower restoration costs.

Feb 23, 2014

By H. R. Manouchehri

In flotation practices, as particles become finer, such as smaller than 20 μm, process efficiency declines markedly. Selective agglomeration of fine particles is a technique to enhance the recovery of fine valuable minerals in flotation circuits. Different agglomerating methods have been introduced and tested. One method that has recently received much attention is to make use of magnetic force to aggregate fine particles. A selective aggregation of fine paramagnetic particles, such as sulfide minerals, can be achieved in the high-intensity magnetic field prior to or during flotation. The method is simple, selective and effective for fine particles and has low operational cost, though a minimum magnetic susceptibility for fine grains is required to promote the process. In this paper, the implementation of the ProFlote magnetic conditioning device in Boliden’s Garpenberg old concentrator in Sweden, where a complex massive sulfide ore is treated, is presented and discussed based on Boliden’s Garpenberg plant. The results showed an increase in the flotation recovery of fine valuable minerals. Zinc (Zn) production was increased by between 1,100 and 1,500 t/a, while salable yearly silver (Ag) production was increased by 1,500 kg. The copper (Cu) grade in the final concentrate was increased by 1 percent, while reductions in its Zn and lead (Pb) grades were obtained. Moreover, considerable reduction in Zn deportment to the final tail was observed

By Setareh Afrouz, Emily Sarver, Cigdem Keles

The resurgence of severe lung disease among US coal miners since the mid-1990s has led to efforts to better characterize and monitor respirable dust exposures, particularly focusing on mineral constituents from rock strata surrounding the coal. A rapid analysis method for silica (quartz) mass using direct-on-filter Fourier transform infrared (FTIR) spectroscopy has been developed, which can also estimate kaolinite, a primary silicate mineral in many coal mines.

Feb 24, 2022

By E. Krystad, G. Tranell

"The kinetics of boron removal from liquid silicon during slag refining, as a process step in the production of solar grade silicon, has been investigated by means of small scale mass transfer experimental series at 1600°C, using a graphite crucible. The slags were SiO2-CaO based, with or without addition of approx. 19 wt% MgO. Experiments were carried out at slag-metal ratios of 1 or 2, where the silicon initially contained approx. 250 ppm boron. The metal-slag mass transfer coefficients for boron were found to be in the order of 1-3 · 10-6 m/s and were largely influenced by slag composition. The mass transfer rate was higher for the MgO-containing slag than the slags without MgO. The final equilibrium distribution of boron between metal and slag, LB, was determined to be in the order of 2.3-3.3.I. INTRODUCTIONRecent years have seen a race in industry and research aimed at obtaining a reliable metallurgical route for production of silicon for solar cells (SoG-Si) from metallurgical grade (MG) silicon. Metallurgical routes can successfully challenge the traditional chemical routes for production of SoG-Si if they generate metal of sufficient purity while being less expensive in terms of production cost and energy consumption. Efficient removal of boron is one of the greatest obstacles in the refining of silicon by a metallurgical route, because the segregation coefficient of boron in silicon makes directional solidification unfeasible; in addition, the vapour pressure of boron is not high enough for removal by vacuum refining. However, the thermodynamic properties of boron makes removal from silicon by oxidation possible, and thus the process of slag refining of silicon has been receiving increasing attention as a method for boron removal."

Jan 1, 2012

By Brian Lewis, Reinhold Daykin Schnell

Blasting is the primary and most effective method for breaking and moving material at most mine sites. The blast design is often adjusted in efforts to optimize the effectiveness of the blasts’ explosive energy while minimizing costs. When adjusting blast design parameters, it is important to adjust one parameter at a time, observing and analyzing the potential effects of the change on the overall blast performance.

Feb 6, 2023

By E. A. Pelczarski

Initially, the objective of this contract was to develop a PWSCSR that could meet proposed criteria (that were different from 30 CFR 11(Title 30 of the Code of Federal Regulation part II) and that would be less than twice the size and weight of a filter self rescuer. This objective was met. Consequently, the original contract was extended to develop a PWSCSR that would meet existing CFR-30 criteria within the same size and weight constraints. This resulted in the development of a PWSCSR (the SR-100) that received NIOSH/MSHA approval (TC-239). This report presents a historical discussion of the design and development of the SR-100 as developed by CSE Corporation under Bureau of Mines contract number H0368013. The technical parameters and the test results of NIOSH/MSHA 30 CFR 11 certification are also presented.

Jan 1, 1990

By Yan Beygelzimer, Alexander Spuskanyuk, Victor Varyukhin

"A cellular model of the plastic deformation of polycrystalline aggregate is proposed and comprehensively described. Representative volume element (RVE) of a solid body, that is being deformed, is described as a population of interconnected units that, in turn, can consist of lower scale level units. Sliding along the various allowed sliding systems deforms simple units, which do not have an internal structure. For consideration of stress distribution within the limits of components, the approach of self-consistent field is used. Rotation of units and moment stresses connected with it are taken into account. Results of computer experiments are analyzed.1. IntroductionMicromechanical models of polycrystals are a link between the research of plastic deformation on micro and macro levels. Computer simulation of inelastic strain of polycrystals has found a great deal of interest as well. Despite the fact that this approach does not allow to obtain macroscopic constitutive relationships that are used in deformed solid body mechanics, it clarifies essential features of the phenomena in many aspects. First of all, it concerns effects stipulated by interdependence of micro-level and macro level of plastic deformation processes. Also, with the computing mechanics, instead of constitutive relationships, the adequate computer models can be used. Broad possibilities for computer simulation of various processes are opened by cellular automata approach. By means of numerical experiments, the cellular automata allows to study the macro behavior of the whole ensemble of cells depending on the local microscopic laws that define evolution of each cell and its interaction with the closest environment.We propose a mathematical model of a polycrystalline aggregate (the cellular model) based on a self-consistent scheme and on the interaction law similar to the one by Berveiller and Zaoui [1]. Our original solution is the self-similar structure of cellular automata that allows modeling of the fractal nature of real materials (Figure 1). The goals of this work are to present the major structures and relations of cellular model of polycrystal and to test this model for its adequacy as for describing known effects and dependencies. Identification of the model and its application for studying of concrete polycrystals are put aside for the future research."

Jan 1, 2001

By G. W. Jones

In a previous report results were given and a method outlined whereby from a knowledge of the composition of the natural gas and of the inflammability limits of the individual constituents composing the natural gas, the limits of inflammability of natural gas and air mixtures could be closely calculated. This method is based on the application of Le Chatelier&apos;s law as modified by Coward, Carpenter and Payman, to apply to a mixture of any number of combustible gases. This law must not be used indiscriminately, because many exceptions have been found. For example, when ethylene, acetylene, hydrogen sulphide, or chlorinated hydrocarbons are present the law may not hold. For a discussion of the rally exceptions which have been found, reference should be made to a report by Coward and Jones. Before this method can be used the inflammable limits of the individual constituents must be known. Also, the composition of the complex combustible mixture, and representative mixtures besides, must be tested both experimentally and by calculation to prove whether Le Chatelier&apos;s law may be applied.

Jan 1, 1933

By Aline Lima da Silva

The reduction in SOFC operating temperature due to recent development in materials and fabrication techniques enables the use of ferritic stainless steels as interconnects for SOFCs. Ferritic stainless steels offer many advantages over traditional ceramic interconnects, such as higher thermal and electronic conductivity, as well as relative ease of fabrication. However, the formation of chromium oxide on ferritic stainless steel results in an increase in ohmic resistance and can lead to the loss of cathode catalytic activity (due to Cr volatilization, with cathode poisoning). The oxide growth depends on several factors, such as steel composition, temperature, oxygen partial pressure. In this way, knowing the phase stability, the oxidation behavior of the material and the oxidation kinetics is of great interest. In this context, a thermodynamic study of the oxidation of ferritic stainless steel 430 under oxidizing atmosphere (cathode), at the temperature of 750ºC, is carried out. As one can see, the thermodynamic system can be very complex, involving several phases (chromium oxide, (Fe,Cr,Mn)3O4 Spinel, iron-chromium oxides, etc.). The effect of oxygen partial pressure and alloying elements on phase distribution is evaluated. Thermodynamic modeling is compared with experimental results from literature.

Aug 8, 2018

By E. G. Bailey

PLANTS that normally burn coal now able too obtain a substantial increase over their normal supply for their greater power needs, and also additional tonnage for extra storage against the uncertainties of the future. Many plants previously burning oil or gas have already been converted to coal, and those which must yet change to coal will undoubtedly be able to obtain ample tonnage of coal of standard quality at reasonable prices. What a contrast this is to the conditions of 25 years ago, when the shortage of coal and transportation led to prices of $5 to $6 per ton at the mines, and degradation of quality, until the already overburdened railroads were called upon to haul 100,000 ton per day of extra ash alone. This was the result of a runaway market and the loading of gob, slate, and sub-quality coal amounting to an estimated increase in ash of 5 per cent of the total tonnage hauled. The problem of getting increased steam output from inferior coal caused unbelievable reductions in the low normal boiler efficiency of that time and untold labor in firing the hand- and stoker-fed furnaces of that day.

Jan 1, 1942

By D. Collins, J. Winfield, V. Gangrade, B. Slaker, S. Braganza

"Researchers at the National Institute for Occupational Safety and Health (NIOSH) are investigating the unique pillar stability issues associated with room-and-pillar mining in dipping underground stone mines. The objective of this paper is to study the post-blast impact in and around a pillar, using microseismic monitoring. To accomplish this, a microseismic monitoring system has been installed at a dipping underground stone mine in central Pennsylvania. The microseismic system is comprised of 18 uniaxial accelerometers; 12 sensors are installed in a single pillar and 6 sensors are installed in the surrounding area. More than 4,400 microseismic events have been located near the study pillar following the blasts. The number of triggers increased significantly following the blast, and the trigger rate in the first five minutes was 60 triggers per minute and three triggers per minute over the next three hours. The processing of high-quality triggers indicated a large number of low magnitude microseismic events near the blasting face. The event locations were identified more accurately by using a 3D-velocity model, with an average 9 m expected location accuracy for this array calculated using the system data. Seismicity was absent from the core of the pillar, but significant numbers of events were found following cutter roof along a crosscut as it was developed as well as in the location of a rib failure event. Additionally, the events were located in the roof, showing high number of microseismic events within 0–10 m of the roof line compared to 10–30 m above the roof line.INTRODUCTIONGround control stability is essential to any mining operation for ensuring mineworker safety and health and preventing catastrophic failures of underground structures. The National Institute for Occupational Safety and Health (NIOSH) has conducted research in stone pillar design and has established fundamental pillar design guidelines for the underground stone industry, which resulted in the development of the S-Pillar program (Esterhuizen et al., 2011; Esterhuizen and Murphy, 2018). However, the data that makes up the S-Pillar database consists of shallow depth, flat-lying, single-level mining operations. Therefore, to expand this dataset and to develop guidelines for challenging conditions such as dipping and multi-level mines, NIOSH is currently conducting detailed pillar response investigations at mines with these characteristics. The study is being conducted using multiple research approaches, including seismic modeling and tomography, numerical modeling (Sears et al., 2019), stress monitoring, and LiDAR-based laser scanning (Slaker, Murphy, and Winfield, 2019). This paper discusses the findings from the microseismic monitoring system installed at the Pleasant Gap Mine, a steeply dipping underground limestone mine in central Pennsylvania."

Jan 1, 2019

By Nicolás Ariel Zabala

During the make-up and break-out of the connections, threaded joints are exposed to intense mechanical and tribological solicitations. The connection performance is influenced by its geometry, material properties, surface treatments and thread compound. The aim of this work is to evaluate and characterize the tribological behavior of different thread compounds applied on manganese phosphated carbon steel under low speed and high pressure sliding contact. Four thread compounds were evaluated: one containing lead, zinc and graphite; other lead-free, containing copper and finally, the last two lead-free and containing non-metallic solids. The tribological behavior was analyzed by a block-on-ring tribotest. During the test, load varied linearly between 250 N and 7000 N; loading and unloading lasted 14 sec and were performed in opposite directions of rotation to simulate the make-up and break-out operations. Friction force and load as a function of time were registered. Upon completion of the test, wear surfaces were analyzed by SEM, optical microscopy and energy dispersive spectroscopy. The obtained results show that the lead and zinc containing thread compound displayed the best behavior, showing a wear reduction of approximately 20%. These results are in line with previously known oilfield experience. Average COF values around 0.15 were measured and no significant differences between dopes were observed; indicating that the wear behavior was influenced by the additive package.

Jul 31, 2018

Two different techniques were used to make measurements of the absolute value of electromagnetic noise in an operating coal mine, Robena No.4, located near Waynesburg, Pennsylvania. One technique measures noise over the entire electromagnetic spectrum of interest for brief time periods. With present instrumentation, the spectrum can be covered from 40 Hz to 400 kHz. It is recorded using broad-band analog magnetic tape, and the noise data are later transformed to give spectral plots. The other technique records noise envelopes at several discrete frequencies for a sufficient amount of tine to provide amplitude probability distributions. The specific measured results are given in a number of spectral plots and amplitude probability distribution plots. The general results are that at frequencies below 10 kHz, power line noise within the mine is severe. Impulsive noise is severe near arcing trolleys, and at lower frequencies near any transmission line. Carrier trolley phone signals and harmonics are strong throughout the mine whenever the trolley phone is in operation. Additional information beyond that included in this report may be obtained from the authors, who are with the Electromagnetics Division of the National Bureau of Standards.

Jan 1, 1974

By Valentine Chanturiya, Irina Khabarova, Maria Ryazantseva, Igor Bunin

"XPS investigations of the influence of HPEMP - treatment duration on the surface composition for natural chalcopyrite and sphalerite are described. HPEMP is a video pulse with a nanosecond front lasting between 5 and 10 ns. The electrical field component can reach 30 kV, whereas pulses repetition frequency is 100 Hz. In general, the formation of metal-deficient surfaces, polysulphides or elemental sulphur and oxides/hydroxides, were determined during the treatment for both sulphides as well as the essential differences of the way of mineral surface transformation during the treatment. The chalcopyrite surface shows the formation of elemental sulphur under the HPEMP treatment at 103 pulses while appearance of unstable sulphite species was detected at the chalcopyrite surface within 5 seconds (0.5•103 pulses) under the same treatment conditions. The results indicate that the quantity of adsorbed water (at.%) is changed considerably during the HPEM - treatment depending on treatment duration for both minerals. The concentration of water onto the chalcopyrite surface decreased during 30 seconds (3•103 pulses) of the HPEMP - treatment and it rose after the treatment at 5•103 pulses. The inverse dependency was obtained for sphalerite surface. Single mineral flotation tests have shown the significant increasing of the minerals recovery."

Jan 1, 2014

By Lukas Erkurt, Wolfgang Holzer, Stefan Auderer, Richard Gradnik

SEM/ NATM Tunnelling contracts in Austria and Germany are usually tendered applying unit price contracts. The purpose of this paper is to show how contractual problems are resolved in these countries. The focus will be put on describing the theoretical approach, several case studies will show how contractual problems were dealt with on site.

Jun 23, 2024

By E Garbarino, P Molina, V Badino

Given the ever increasing quantity of construction and demolition waste (C&amp;DW), one of the most challenging issues presently facing policymakers and public administrators in Italy concerns how to organise and manage collection and recycling and to understand whether and to what extent recycled aggregate can complement natural building aggregates in a sustainable supply mix (SSM). The paper presents the results of a research aimed at analysing energy and environmental implications of the C&amp;DW recycling chain in the administrative territory of Provincia di Torino in northern Italy. In respect of a population of about 2.25 million inhabitants, the annual production of C&amp;DW in the area under study is 1.8 Mt. A combined geographical information system (GIS) and Life Cycle Assessment (LCA) model was developed, paying attention to the geographical location, land use, transportation network and avoided landfill: crucial issues for sustainable planning and management. Around 90 recycling plants were classified according to the size, typology (stationary, semi-mobile and mobile) and physical- mechanical characteristics of the recycled aggregate. Under different assumptions relevant to the delivery distance, and considering the typology and grade of recycled aggregate, as well as local availability of natural aggregates, it was possible to evaluate the geographical coverage of aggregates demand and to use LCA in order to identify and quantify energy and environmental indicators.

Jan 1, 2009