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By R. J. Matetic

The National Institute for Occupational Safety and Health (NIOSH) has recognized that Noise-Induced Hearing Loss (NIHL) is the most common occupational illness in the United States. The use of heavy equipment, the drilling of rock, and the confined work environment are some of the factors that contribute to high levels of noise exposure to workers in the mining industry. Every day 80% of the nation’s miners go to work in an environment where the time weighted average (TWA) exceeds 85 dBA. Moreover, 25% of the miners are exposed to a TWA noise level that exceeds 90 dBA, the Permissible Exposure Limit (PEL). Furthermore, a NIOSH analysis of a large sample of audiograms showed that at age 50 approximately 90% of coal miners and 49% of metal/non-metal miners have a hearing impairment. By contrast, only 10% of the non-occupational-noise exposed population has a hearing impairment at age 50 (Franks, 1997) (Stephenson, 1998). Simply stated, the majority of miners have a hearing loss by the time they retire. While NIHL is the most common occupational disease in this country, this problem is especially acute among workers in the mining industry. There are several barriers to reducing NIHL in the mining industry. These include: gaps in knowledge of noise dose/source relationships, the unavailability of effective noise controls, and needs for worker education and worker empowerment. A related issue is the difficulty of communication in noisy workplaces by both hearing impaired and normal hearing workers. The Pittsburgh Research Laboratory (PRL) at NIOSH has strategically developed a hearing loss prevention program for overcoming these respective barriers in an attempt to reduce NIHL in the mining industry. This paper provides an overview of the research program being conducted at the PRL.

By David C. Byrne

PURPOSE: Evaluate practical technological advances in level-dependent hearing protectors and inexpensive personal acoustic monitors. RESEARCH SUMMARY: The results of previous NIOSH research show that miners develop hearing loss much more quickly than nonoccupationally noise-exposed individuals and that miners experience a greater severity of hearing loss than would be expected for nonoccupational noise-exposed persons of the same age and gender. Using hearing thresholds at 4,000 Hz as an indicator, coal miners experience hearing loss 2.5 to 3 times greater than would be expected for persons not exposed to occupational noise. At age 50, 90% of coal miners and 49% of metal/nonmetal miners were found to have a hearing impairment. In comparison, only 9% of a nonoccupationally exposed control group had a hearing impairment at age 50. There are numerous barriers to the prevention of hearing loss among miners. In an effort to overcome some of these obstacles, this work was initiated to evaluate practical technological advances in level-dependent hearing protectors and inexpensive personal acoustic monitors. Experiments will involve analysis of this new technology under both laboratory and field conditions. Laboratory components will consist of controlled studies using an anthropometrically correct test fixture as well as human subjects to evaluate the adequacy/effectiveness of various hearing protective devices. Electroacoustical performance testing of new noise monitors will also be conducted in a laboratory setting. Subsequent field studies will determine the actual usefulness and practicality of the personal protective/monitoring equipment as used in different mining situations. It is anticipated that increased on-the-spot awareness of hazardous noise levels and the availability of better-suited hearing protectors will provide a degree of protection beyond what is currently attained in different mining environments. Therefore, the intent of this project is to identify and adapt new acoustical technologies and products that have a direct application to individual mine workers. With increased knowledge of these technological advances, a greater demand for similar devices will likely occur, which, in turn, will lead to a better understanding and awareness of hearing loss prevention methods throughout the mining community. The ultimate goal is for widespread integration of useful hearing loss prevention products and devices into the daily routines of miners

Jan 2, 2000

PURPOSE: Evaluate practical technological advances in hearing protective devices for use in different mining environments. RESEARCH SUMMARY: Previous NIOSH research shows that miners develop hearing loss much more quickly than nonoccupationally noise-exposed individuals. Also, miners experience a greater severity of hearing loss than would be expected for nonoccupational noise-exposed persons of the same age and sex. As described in the National Occupational Research Agenda, problems created by occupational hearing loss include (1) the reduced quality of life due to social isolation and unrelenting tinnitus, (2) impaired communication with family members, the public, and coworkers,(3) a diminished ability to monitor the work environment (e.g., warning signals, equipment sounds, etc.), (4) lost productivity and increased accidents resulting from impaired communication and isolation, and (5) expenses for workers? compensation and hearing aids.

Jan 1, 2000

PURPOSE: Evaluate practical technological advances in hearing protective devices for use in different mining environments RESEARCH SUMMARY: Previous NIOSH research shows that miners develop hearing loss much more quickly than nonoccupationally noise-exposed individuals and that miners experience a greater severity of hearing loss than would be expected for nonoccupational noise-exposed persons of the same age and sex. As described in the National Occupation-al Research Agenda, problems created by occupational hearing loss include(1) reduced quality of life due to social isolation and unrelenting tinnitus,(2) impaired communication with family members, the public, and coworkers, (3) diminished ability to monitor the work environment (i.e., warning signals, equipment sounds, etc.), (4) lost productivity and increased accidents resulting from impaired communication and isolation, and (5) expenses for workers? compensation and hearing aids.

Jan 1, 2001

By David C. Byrne

PURPOSE: Evaluate practical technological advances in hearing protective devices for use in different mining environments. RESEARCH SUMMARY: Previous NIOSH research shows that miners develop hearing loss much more quickly than nonoccupationally noise-exposed individuals and that miners experience a greater severity of hearing loss than would be expected for nonoccupational noise-exposed persons of the same age and sex. As described in the National Occupation-al Research Agenda, problems created by occupational hearing loss include(1) reduced quality of life due to social isolation and unrelenting tinnitus,(2) impaired communication with family members, the public, and coworkers, (3) diminished ability to monitor the work environment (i.e., warning signals, equipment sounds, etc.), (4) lost productivity and increased accidents resulting from impaired communication and isolation, and (5) expenses for workers’ compensation and hearing aids. Although eliminating hazardous noise is the long-term solution to the noise problem, miners will likely need to rely on personal hearing protection in certain situations for quite some time. However, it is well known that noise attenuation provided by hearing protectors as they are worn during everyday use is usually quite different (i.e., worse) than when tested under lab conditions. In addition, workers may refuse to wear their hearing protection for any number of reasons. This project was initiated to evaluate practical technological advances in hearing protectors, with an emphasis on optimizing the balance between effectiveness, comfort, over protection, and communication ability. The recently completed auditory research facility is now under-going the accreditation process conducted by the National Institute of Standards and Technology under the National Voluntary Laboratory Accreditation Program. Experiments are planned to investigate the factors that affect a miner’s ability to hear hazard and warning sounds (e.g., roof working, alarm signals, spoken communications, etc.). A service contract has been initiated to record and digitally store samples of typical warning sounds heard in an underground coal mine. This information will be analyzed in the lab to develop recommendations that can be offered to the mining community regarding correct earplug/earmuff usage to maximize there cognition of hazard and warning sounds while adequately protecting the miners’ hearing.

Jan 12, 2001

By David C. Byrne

PURPOSE: Evaluate practical technological advances in hearing protective devices for use in different mining environments. RESEARCH SUMMARY: Previous NIOSH research shows that miners develop hearing loss much more quickly than nonoccupationally noise-exposed individuals. Also, miners experience a greater severity of hearing loss than would be expected for nonoccupational noise-exposed persons of the same age and sex. As described in the National Occupational Research Agenda, problems created by occupational hearing loss include (1) the reduced quality of life due to social isolation and unrelenting tinnitus, (2) impaired communication with family members, the public, and coworkers,(3) a diminished ability to monitor the work environment (e.g., warning signals, equipment sounds, etc.), (4) lost productivity and increased accidents resulting from impaired communication and isolation, and (5) expenses for workers’ compensation and hearing aids. Although the elimination of hazardous noise is the ideal long-term solution to the noise problem, miners will likely need to rely on personal hearing protection in certain situations for quite some time. However, it is well known that noise attenuation provided by hearing protectors as they are worn during everyday use in the workplace is usually worse than when tested under laboratory conditions. Additionally, workers may refuse to wear their hearing protection for any number of reasons. Therefore, this project was initiated to evaluate practical technological advances in hearing protectors, with an emphasis toward optimizing the balance between effectiveness, comfort, overprotection, and communication ability. Currently, the necessary in-house laboratory facilities and research techniques are being finalized. Individual experiments are planned that involve analysis of new hearing protector technology under both laboratory and field conditions. The laboratory components are to consist of con-trolled studies using human subjects and/or an anthropometrically correct artificial test fixture to evaluate the adequacy/effectiveness of various hearing protective devices. Field studies are planned to determine the actual usefulness and practicality of the hearing protectors as used in diferent mining environments. Recommendations can then be offered to the mining community regarding correct earplug/earmuff usage that maximizes recognition of hazard/warning sounds while adequately protecting the miners’ hearing.

Jan 12, 2000

PURPOSE: Evaluate practical technological advances in level-dependent hearing protectors and inexpensive personal acoustic monitors. RESEARCH SUMMARY: The results of previous NIOSH research show that miners develop hearing loss much more quickly than nonoccupationally noise-exposed individuals and that miners experience a greater severity of hearing loss than would be expected for nonoccupational noise-exposed persons of the same age and gender. Using hearing thresholds at 4,000 Hz as an indicator, coal miners experience hearing loss 2.5 to 3 times greater than would be expected for persons not exposed to occupational noise. At age 50, 90% of coal miners and 49% of metal/nonmetal miners were found to have a hearing impairment. In comparison, only 9% of a nonoccupationally exposed control group had a hearing impairment at age 50.

Jan 1, 2000

By David Ingram

The results from the sound level measurements, the dosimeter recordings and the time-activity studies on four different air-rotary rigs indicate a wide variation of operator noise exposure during hole development. These variations appear to be dependent on the cab design and the operator?s drilling behavior. Studies have documented that exposure to high sound levels for long periods of time can cause hearing loss. The results of this study help identify the loudest parts of the drilling cycle. Sound level measurements on the four rigs show that all the rigs generate sound levels that are 90 A-weighted decibels (dB(A)) and above within 6 feet around the rigs during drilling. It is easy to conclude that some type of noise protection, such as a cab, is needed to protect the operator from overexposure to noise for an eight-hour shift of uninterrupted drilling. However, even when rigs are outfitted with cabs, operators observed in this study are being exposed to sound levels above 90 dB(A) during some activities required to complete a drilling cycle. An evaluation and comparison of the four dosimeter recordings and time-activity studies during one drilling cycle may explain why variations in operator exposure occur. Table 1 summarizes the time-weighted average (TWA) and accumulated dose percentages for each of the four operators during the time needed to complete one typical hole cycle.

Jan 1, 2008

By Munive L

As a result of commissioning No.5 B F, 2670m3 inner volume, in March 1972, the largest B F in Australia; new expertise in maintenance, furnace operating practices and design have been obtained. This experience has also been extended to the other furnaces. A series of operating problems were con- fronted; all parts of the furnace, including the hearth side walls and bottom,were adversely affected. In December 1977, serious hearth wall wear was detected at No.5 B F, and a potential hearth breakout was averted. Hearth wear in No.4 B F was discovered in March 1979, and emer- gency underhearth cooling was installed to reverse an extremely advanced hearth bottom erosion. Hearth behaviour of No.5 B F oampaign 1972-1978 and`No.4 B F campaign commencing 1972, has been studied and discussions on the causes, effects and measures undertaken to protect the hearths are presented in this paper.

Jan 1, 1981

By Frank P. Frandina, Michael J. Loehr, Paul E. Gabryszak

The Heartland Corridor Clearance Improvement Project is part of a regional Public-Private initiative to allow double stack container trains a direct route from the Port of Norfolk through Virginia, West Virginia, Eastern Kentucky and into Central Ohio. In the Preliminary Engineering stage, 30 existing tunnels were assessed and 28 were found to need clearance improvements to allow the use of double stack trains. Alternative tunnel enlargement methods were developed to achieve the desired clearance improvements, while maintaining structural integrity and minimizing disruption to train traffic. This paper summarizes the geometric and condition investigations of the existing tunnels, as well as describes the preferred methodologies to achieve the desired clearance. The clearance improvements will be implemented beginning in the summer of 2007.

Jan 1, 2007

By Frank P. Frandina

The Heartland Corridor Clearance Improvement Project is part of a regional Public-Private initiative to allow double stack container trains a direct route from the Port of Norfolk through Virginia, West Virginia, Eastern Kentucky and into Central Ohio. The project involves clearance improvements to twenty-eight tunnels, twenty-one of which require structural modification. With construction of the first Package of tunnels just underway at press time, this paper summarizes the program implementation from design through the initial stages of construction.

Jan 1, 2008

Reduce fire warning time and avoid activation of false alarms in underground mines. Approach A heat activated stench/tracer gas system was developed which automatically releases the gas mixture into the mine ventilation air. How It Works A canister approximately 12 inches long and 3 inches in diameter is charged with 50 grams of ethyl mercaptan or other appropriate stench gas and 500 grams of instrument detectable Freon. The canister is then pressurized to 100 psi with nitrogen. A disc is used to seal the contents of the canister. A low-temperature alloy designed to melt at a predetermined temperature is used to restrain a spring loaded plunger. Upon exposure to heat, the alloy melts and the plunger is released. The plunger ruptures the disc and the mixture of stench and tracer gas is released from the canister. Canisters are mounted in areas of a mine which are susceptible to fire such as near

Jan 1, 1983

By P. Somasundaran, D. W. Fuerstenau

Adsorption isotherms for dodecyl sulfonate on alumina were determined at 45°C and 25°C and the data was used for calculating the partial molar heat and entropy of adsorbed ions under various concentrations. Changes in OH and AS observed at certain concentrations agree with the postulate of interaction of surfactant ions to form two-dimensional aggregates at the solid-liquid interface. Values of the total OH and AS for the aggregation process calculated using the Clausius-Clapeyron equation is used to interpret the interactions of surfactant ions with each other as well as with the solvent molecules.

Jan 1, 1973

By A. De, J. S. Zuback, T. Mukherjee, T. DebRoy

For successful commercial applications of additive manufacturing, metallic parts need to be defect free, structurally sound and reliable. However, additively manufactured metallic parts are susceptible to distortion, lack of fusion defects and compositional changes. Methods to measure susceptibilities of various alloys to these defects are needed but not currently available. Here we show that the necessary theories can be developed based on a well-tested numerical heat transfer and fluid flow model and decades of research in the field of welding. The proposed theories are validated with experimental results reported in the literature.

Jan 1, 2016

By J. McKelliget, J. Szekely, Oreper. G. M.

"1. INTRODUCTIONThis paper is concerned with heat and fluid flow phenomena in arc welding operations. Fig. 1 shows a schematic sketch of a typical arc welding arrangement. It is seen that an arc is being struck between an inert electrode and a metal surface and that the resultant current and energy flow will case the formation of a molten weldpool.It is clearly appreciated that the weldpool shape and the nature of circulation in the weldpool may play an important part in determining the ultimate weld quality. It is known, furthermore,· that the weldpool behavior in turn will be affected by the spatial distribution of the current and the heat flux it receives from the arc. Indeed, the inherent coupling between the arc and the weldpool is a key feature of welding operations.Up to the present useful work has been done on the modelling of heat transfer and melt circulation in weldpools (1,2,3,4) and also on the description of arcs, including welding arcs (5,6,7,8). However, the coupling between these two sets of phenomena is relatively unexplored in a qualitative sense. The purpose of the present paper is to examine the interaction between welding arcs and weldpools. The actual material will be presented under the following headings:"

Jan 1, 1986

By Antti Roine

Sulfidic zinc concentrates are usually roasted in a fluidized bed furnace into sulfur-free oxide form. Metallic zinc is produced from this oxidic calcine using hydrometallurgical leaching, solution purification and electrowinning stages. The roasting step is necessary because zinc oxides are easier to dissolve using traditional leaching methods than zinc sulfides. The Kokkola Zinc smelter uses various types of zinc concentrates and secondary materials as feed mixture. This makes it difficult to find optimum process parameters for the roaster when the composition and particle size distribution of the feed mixture varies even on a daily basis. Certain conditions may even cause difficult accretion problems or increase the amount of calcine in the process off-gas line excessively. A thermochemical heat and material balance model was developed for process advisor, in order to estimate the effects of different process parameters (temperature, process air coefficient, concentrate feed, oxygen enrichment, water feed, etc.) on the heat balance, roasting temperature and calcine composition. This model was constructed using the heat balance module of HSC Chemistry 4.0 software. The prevailing chemical compounds in the concentrate and calcine were verified using mineralogical analyses and equilibrium calculations. The roasting process seems to operate near chemical equilibrium conditions, if the behavior of the main components is considered. This paper describes briefly the basic principles of the calculation model and outlines the results with several diagrams and discussion. The calculated results were in reasonable agreement with the recent process air oxygen enrichment and water feed test campaigns carried out at Kokkola in 1999.

Jan 1, 2000

Au airway hteat and moisture exchange .,Jgorithm is described which is generalised to suit most mining situations and can be run separately on a microcomputer or used within a network simulation. The main difference between this technique and other simplified methods is that a non-uniform boundary condition is allowed for. This permits radiative heat transfer between surfaces of different wetness in addition to evaporative and convective heat and mass transfer.

Jan 1, 1988

By I. Longson

As a longwall coalface advances a caved goaf or waste region is left behind. Air flow takes place through this permeable goaf due to the pressure differentials existing across it and en route this leakage air picks up both heat and moisture. A marked deterioration in climatic conditions occurs in the face area at all points downstream of where this leakage air rejoins the main air-stream. This goaf heat source can make a very significant contribution, typically 30-40% to the rate of total heat pickup on an advancing UK longwall coalface with a VST of 40°C and hence on the climatic conditions that prevail at the return end and in the return gate of the face. The magnitude of the rate of heat collection from the goaf depends on a number of factors but it has been established that it is particularly influenced by the prevailing virgin rock temperature and the total flow rate of the leakage air. This paper proposes a model for the goaf based on a packed bed analogy and other assumptions required in order to evaluate the rate of heat pickup are identified. The outlet condition of the leakage air predicted by the model have been shown to correlate with underground measurements taken for a range of different production patterns with the face cutter at various locations on the face. The sensitivity of these predictions to variations in the input data has been tested and is commented on. At this stage of the development the capabilities and predictive limitations of the model are discussed. Further areas of investigation are suggested in order to improve the predictive ability and to extend the versatility of the model.

Jan 1, 1989

By J. E. Lamar, J. S. Machin

INSULATING materials include a wide variety of nonmetallic mineral products such as exfoliated vermiculite, expanded gypsum, 85 pct magnesia, diatomite, asbestos, perlite, cellular glass, pumice, silica aerogel, expanded aggregates and mineral wool. Except mineral wool, most of these products, or the materials from which they are manufactured, are described in other chapters of this book. PROPERTIES OF INSULATING MATERIALS The insulating properties of the materials considered in this chapter result in general from entrapping extremely small pockets of air in such a manner that heat is not transferred by convection. The minimum heat conductivities of such insulating materials are slightly greater therefore than the conductivity of still air. In addition, conductivity varies with the overall density of the material, the temperature range in which the measurements are made, and the form into which the material is fabricated. However, the numerical value of heat conductivity should not be the sole criterion of an insulating material; for a particular application it may be advantageous to use a material of somewhat higher conductivity in order to secure other desirable engineering properties. This is especially true with certain materials that are used because of their refractoriness. Comparative insulating values of some commonly used insulating materials are shown in Table 1. In comparing the values presented in this table it should be borne in mind that heat conductivity varies with the mean temperature, with the overall density, and with the amount of moisture present. With fibrous or granular materials it varies with fiber or grain size and with the amount and kind of binder, if any is used. Under some circumstances it may vary with the arrangement of

Jan 1, 1949

By T. Kho, W. Zhang, M. E. Reed

The control of flash furnace heat balances is critical. Suspension smelting control and stability comes from stable operation of the heat balance, and this leads to a stable reaction shaft exit temperature. A number of flash furnace operations have been reviewed to determine if the application of this approach is beneficial for their operation. The cause and effect relationship between reaction shaft exit temperature with uptake and throat buildup is being enhanced with this work program. Our operating personnel are exposed to the operational hazards of cleaning this buildup from the throat and it is imperative that as an industry we continue to look for repeatable solutions. WorleyParsons has reviewed operational data from a number of flash furnaces and looked at the possible improvements that can be made to decrease variation in the reaction shaft exit temperature. The data assessed for each operation illustrate the need to fully understand the process inputs to the particular operation and to ensure that the control changes are correctly impacted. In the plant data that have been assessed for a number of operations combinations of feed changes and inappropriate process decisions have lead to changes in reaction shaft exit temperature which impact the overall furnace operation and the uptake shaft condition, and ultimately the boiler. INTRODUCTION In 2016 WorleyParsons jointly prepared a paper outlining the effects of heat balance control on the Olympic Dam flash furnace (Reed et al, 2016). That paper investigated the importance of heat balance control in flash furnaces and demonstrated the changes made at the Olympic Dam operation to control the heat balance in the furnace and the impact that change had. The operation is still using the tool to assist in trouble shooting performance and pinpointing problems that may lead to issues in the furnace throat and Waste Heat Boiler (WHB). As a result of the interest in the methodology and due to the issues surrounding safety and process performance caused by WHB throat buildup and damage, WorleyParsons approached a number of flash furnace operators to discuss the application of the approach at their operations.

Jan 1, 2019