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By Edmund H. Warner

Any city dweller who has walked alone along a remote mine passageway has to be impressed by the eerie silence - the total absence of noise except for ones own breathing and scuffing of boots on the bottom. An underground mine can have tremendous contrasts, from complete silence to the ear piercing clatter of percussion drills working on the mine roof. Noise in underground mining machines is both useful and detrimental. Without characteristic noises that are recognizable to miners, operators would have a more difficult job operating their machines. Noise serves as a warning of approaching machinery, and changes in noise give indication that breakdowns may occur. But excessive noise is a health hazard. In recognition of this fact, our Congress included noise exposure as a part of the "Coal Mine Health and Safety Act of 1969". As Fig. 1 indicates, allowable noise exposure is established by specifying a time duration permitted at different noise levels. This is the well known "Walsh-Healey" criteria which governs noise exposure in many industries.

Jan 1, 1977

By J. Alton Burks, Roy C. Bartholomae

The chain conveyor is utilized extensively in underground mining to convey raw ore, especially coal. It is estimated that several thousand loading and continuous mining machines rely on this type of conveyance. Although the chain conveyor is both efficient and highly reliable, its use is generally associated with the production of noise levels that often exceed 105 dBA at the operator's position. Thus, it is one of the most significant contributors to the occupational noise problem experienced by miners in the underground coal mining environment. Conventional engineering noise controls that result in an average reduction of 4 dBA have been previously designed and implemented. However, a novel solution involving a change in conveyor operation has been proposed that takes advantage of two aspects of conveyor noise: 1) conveyor noise has an approximately cubic dependence on conveyor chain speed and 2) due to the damping provided by coal, a full conveyor is 5 dBA quieter than an empty one. An engineering analysis has shown that a significant reduction in the operating noise level of a typical continuous miner can be achieved through the use of an adjustable speed drive automatically controlled by a coal loading sensor that maintains a full conveyor at all times. The potential reduction depends primarily on the mining conditions (coal seam thickness and the presence of either rock or water) and varies from 7-18 dBA. Other benefits to be derived from the use of a variable speed drive include reductions in power consumption, dust, and maintenance costs.

Jan 1, 1992

By J. Partyka, Trevor R. J. Kelly

This paper presents the results on noise testing of a fan only, as well as the results of a steel silencer and of flexible silencers that were connected directly to a fan. On-site facilities and free-field method set by the British Standards Institution were used to measure and then compare the fan only and different practical silencer configuration setups. In order to determine the fan-silencer combination that would give the maximum noise attenuation, total noise intensity, noise contributed to by the fan motor only, as well as aerodynamical noise created through air interacting with the fan parts were considered to obtain decibel readings for the octave bands. Subsequently, the optimal configuration found was the setup with flexible silencers on the fan inlet and the fan outlet. If only one silencer is used, it should be installed on the fan inlet. The aerodynamic noise affects the low frequencies. The flow noise is then overtaken at 1 kHz by the mechanical noise.

Jan 1, 1995

By T. Hart

Nuclear gauging is used world-wide in almost every industry. From mining and ore-grading to finished product, the metallurgical industry is one of the biggest users of nuclear sensors for inventory, process control, and quality assurance. This paper will discuss the basic theory of gamma transmission gauging techniques found useful in mining, milling and metal production. Techniques to be discussed are gamma transmission for level and density. A major new technique will also be discussed. This technique is called gamma backscatter. The uniqueness of this technology, how to apply and the differences between transmission and backscatter will be accentuated.

Jan 1, 2011

By M. A. Kaufman

In this paper I will attempt to present an up to date review of the type of exploration' that has previously been carried out in Alaska, discuss some of the more significant past producers and recent discoveries, and suggest some approaches to future exploration. Hopefully this information may be of some use to those parties tempting to evaluate Alaska's non ferrous, non placer, metal potential or contemplating initiation of exploration in the state. II. SUMMARY AND CONCLUSIONS Past production of non ferrous metals from lode deposits in Alaska has been meager considering the size of the state. Since there have been no major lode mines operative in Alaska since World War II, and since logistical conditions vary throughout the state, it is not possible to generalize with respect to mining costs in Alaska as compared to those in other areas. There seems to be little question, however, that a major deposit situated in a reasonably favorable location' could be profitably operating at present. Host of the known metal prospects in Alaska were discovered by early gold prospectors prior to World War I. From World War I through World War II exploration consisted chiefly of surface prospecting by prospectors on a diminished scale, as compared to the early gold rush days, drilling of some prospects by the U.S.B.M,, and occasional mine or prospect evaluations by mining companies. From the end of World War II to the present time, there has been a generally steady increase in exploration by mining companies consisting chiefly of prospect and district evaluations, large scale aerial reconnaissance programs in search of color anomalies, and regional drainage geochemical surveys. The post World War II increase in mining company exploration has not been matched by an increase in conventional surface prospecting.

Jan 1, 1972

By Ron L. Schmiermund

The Ferris-Haggarty underground mine was abandoned circa 1910, and portal discharge has since resulted in degradation of a trout fishery in the receiving waters of Haggarty Creek. Although tunnel discharge varies dramatically in volume throughout the year due to infiltration of snowmelt, compositionally it is a nearly constant low-TDS, pH-neutral, low-sulfate, copper-silicate dominated water. Between infiltration events, components of ARD accumulate in unsaturated, oxygenated environments within upper workings and are delivered to the main haulage level by the subsequent annual snowmelt flush. Mixing with non-ARD mine waters results in neutralization, dilution, and precipitation of amorphous copper carbonate and silicate phases. These mechanisms, combined with variations in the water balance, control the composition of the portal discharge. Understanding the chemical and hydrologic control mechanisms was critical to the design of a passive treatment system to decrease effluent copper concentrations.

Jan 1, 2000

By Haydn H. Murray

Although alumina constitutes about ii percent of the earth's crust, it is expensive to separate and purify for the production of aluminum with the exception off the alumina in bauxite. The United states has a variety of non-bauxite resources that could substitute for bauxite, including high alumina clays, alunite, dawsonite in oil shale, anorthosite, and nepheline syenite. Each of these resources are discussed from the standpoint of geology, geography, processing, potential recovery, and environmental problems. Potential by-products include silica from clays, potash and sulfuric acid from alunite, soda ash from dawsonite, and soda ash and potash from anorthosite and nepheline syenite.

Jan 1, 1982

By R. Gray

"Experience from Australia has identified what is referred to as non-conventional surface subsidence behaviour. This occurs under irregular surface topography, resulting in valley closure, valley floor uplift or “upsidence”, and far-field horizontal movements – even occurring beyond conventional “angle of draw” limits. This paper discusses such behaviour recently observed in Pennsylvania and focuses on the 2005 case of Duke Lake Dam in Ryerson Station State Park. In July 2005, there was a significant increase in water leakage through a number of growing cracks in the dam leading to the dam being breached to avoid an uncontrolled failure. An underground longwall mine was located approximately 900ft to the north, mining at depths of 330 – 720ft. Investigations (including a subsequent ground movement monitoring program) found a range of evidence in the vicinity suggesting that valley closure and far-field horizontal movements may have occurred resulting from the adjacent mining. The paper discusses the phenomenon of non-conventional subsidence behaviour and the Ryerson State Park case study, including an assessment of mining, geology and subsidence impacts and suggested ground behavioural mechanisms. INTRODUCTION Non-Conventional Subsidence The conventional understanding of coal mine subsidence on which most current subsidence understanding and prediction techniques are based, includes the concept of angle of draw which effectively limits the lateral extent of subsidence effects and impacts. Within this zone – above and marginally beyond the boundary of mining – downward vertical subsidence is the dominant component, together with localised horizontal movements towards the mined region, with related tilts and strains. However, more recent experience from Australia over the last two or three decades has identified what is referred to as non-conventional surface subsidence behaviour. This is found to occur in areas of irregular surface topography or variable terrain, and is characterised by phenomena such as valley closure, valley floor uplift or upsidence, and far-field horizontal movements, all of which can occur beyond the conventional angle of draw limits. NSW Department of Planning (2008) defined the conditions for both conventional and non-conventional subsidence behaviour as follows: “The conventional or general model of surface subsidence, which finds worldwide acceptance, is based on assuming the following site conditions:"

Jan 1, 2015

By Vishwajeet Ahuja, Benoit Jones

"INTRODUCTION Shotcrete lining forms an integral part of conventional tunneling and is widely applied for underground excavations. Early strength gain of the shotcrete is a crucial aspect for ground support and safety of operatives. Strength requirements are dependent on various factors such as lining thickness, ground type, excavation size and tunnel depth. The early strength gain is typically monitored using destructive tests, such as needle penetration, stud driving or coring samples for uniaxial compressive strength testing in the laboratory. Being destructive, these tests cannot be directly performed onto the lining without causing damage that must be repaired, which is a particular problem for permanent linings. For this reason and to avoid the need for operatives to work near to exposed ground and/or fresh shotcrete, these destructive tests are often performed on panels, which are sprayed at the same time as the tunnel lining. All current testing methods are also very local, testing only a small part of the lining or a panel, which may not be representative because the temperature history could be significantly different. Therefore, these tests do not provide an accurate or complete picture of the lining strength gain. New testing methods that are non-destructive and can scan the whole lining remotely would be extremely desirable. This paper describes a new method, using thermal imaging techniques, that achieves these aims. It also discusses the real-time on-site application of the method, providing insight into the experience gained and conclusions derived. Shotcrete Shotcrete used for tunnel linings requires immediate strength development. The strength development is a direct result of the hydration reaction of cementitious materials present in it. A progressive sequence of the hydration reaction changes it from a solid suspension (typically referred to as fresh concrete) to a solid skeleton with a porous network and thereafter, into a solid with predominantly discontinuous pores (Byfors 1980). In the case of shotcrete, early strength is needed to support the self-weight and then continuing early age strength gain is required to begin to support ground loads. These strength requirements, along with other workability needs, are met by careful concrete mix design, the use of admixtures, such as accelerator and superplasticizer (BS EN 934-5 2007), and supplementary cementitious materials, such as silica fume."

Jan 1, 2016

Numerous underground coal mine ventilation seals have been installed in the United States of America prior to 2006 and after implementation of the Mine Improvement and New Emergency Response (MINER) Act. Seal engineering, design, placement, and construction is regulated in industry, but post-construction monitoring of seals is limited to visual inspection of the outby face and seal perimeter, convergence measurement, and atmospheric monitoring. To monitor seal integrity and to provide safe working conditions, a form of non-destructive testing (NDT) is necessary to accurately reflect the health of the seal by detecting post-construction changes, deterioration, or defects within in-situ seals in underground coal mines. Previous research from the National Institute of Safety and Health (NIOSH) has indicated the potential for utilizing ground penetrating radar (GPR) for assessing in-situ mine seals. This paper provides an update to the assessment of proposed NDT methods for seal evaluation using commercially available GPR technologies and systems. Full-scale free-standing seals and large-scale seal specimens were analyzed with an array of GPR units from various manufactures using multiple frequencies.

Feb 23, 2014

By L. Lacerda, C. Rose, E. Zellers

Approximately six hundred air sample measurements were taken at several U.S. underground metal/nonmetal mines in 1998 and 1999. This air sampling effort was organized by the Nevada Mining Association to evaluate mining conditions and to evaluate the Mine Safety and Health Administration’s (MSHA) Proposed Rule on Diesel Particulate Matter Exposure of Underground Metal and Non-metal Miners. MSHA’s proposed air sampling method, NIOSH Method 5040, was tested under controlled conditions and under normal mining conditions. Unfortunately, NvMA sampling results have indicated that carbonaceous rock dust, oil mists and even cigarette smoking create severe sampling interference problems for NIOSH 5040.The main conclusion was that NIOSH 5040 did not distinguish between DPM and other airborne carbon particulate. Thus, it is not a reliable method of accurately and unequivocally measuring DPM in underground metal/nonmetal mines.

Jan 1, 2000

By Stephen G. Hardcastle

CANMET has developed a simple yet very effective tracer gas method to test the efficiency of stench gas emergency warning systems which can easily be performed by mine personnel. This test method uses sulphur hexafluoride (SF,) as a surrogate for such stench gases as ethyl mercaptan. The test has many advantages: it is non-disruptive to production because SF, is odourless, colourless; it is safe to use as it is inert and only a small volume, insufficient to reduce oxygen levels, is necessary to dope the air with a measurable concentration; and most importantly it provides definitive results to assess the adequacy of the warning system. Specific findings of these tests have included, over doping sections of the mine and subsequent production loss due to sickness, the warning being ignored, the injection period being too short, excessive dispersion, and inadequate notification times. The simple test protocol involves releasing a known volume of the SF, under similar circumstances to those of the stench gas, and then sampling for its presence downstream. These samples are collected in air-tight syringes which are then analyzed in a laboratory with a gas chromatograph. By direct proportion, between the size of the stench and tracer gas releases, it is possible to convert the SF, concentration into equivalent stench gas concentrations profiles. From these, it is possible to define, the initial arrival time of the gas, the time it takes to reach a "target" notification concentration, whether the gas peak will exceed TWAEV, STEV and CEV exposure limits, and the duration of the peak above these levels. Since 1993, this test protocol has been employed a total of eight times on four different Canadian mine properties and the results are being used to optimize the stench gas release system with respect to volume of gas used, duration of injection, and number of injection locations.

Jan 1, 1997

By Michael R. Grubbs

In most resource recovery plants the incoming solid waste material is first shredded and then air classified into a light and a heavy fraction. The light fraction which contains mostly paper, cardboard, etc., can be used either as a fuel for power generation or in the production of new paper products. The heavy fraction which remains consists mostly of glass, ceramics, wood, ferrous metals and non-ferrous metals. The ferrous metals may be removed from the heavy fraction by conventional magnetic separators. After primary shredding, most of the glass and ceramic is fine in size and may be screened away leaving a residue of wood, cardboard, and non-ferrous metals. This residual heavy fraction is the input material for the separator described in the present paper. A new metal separator was recently reported by t. Schlömann1. The author described the theoretical relationships and presented results of tests on samples of the residual fraction of municipal solid waste. This paper describes the operation of the metal separator and develops the basic separation relationships controlling the process.

Jan 1, 1976

By K. T. Valsaraj

The separation process called solvent sublation for the removal of two hydrophobic compounds (penta-and tri-chlorophenols) from the aqueous phase is discussed. A steady state mathematical model for the process is discussed. The process was conducted in a continuous countercurrent mode. The underlying mechanisms, theory and experimental details on the effects of process variables on removal efficiency are reported.

Jan 1, 1992

By K. T. Valsaraj, L. J. Thibodeaux

Solvent sublation, the separation process for the removal of two hydrophobic compounds (penta- and trichlorophenols) from the aqueous phase, is discussed, as is a steady-state mathematical model for fire process. Solvent Sublation "'as conducted in a continuous countercurrent mode. The underlying mechanisms, theory and experimental details on the effects of process variables on removal efficiency are reported.

Jan 1, 1994

By Walter R. Jr. Hibbard, William A. Vogely

INTRODUCTION Volatile markets and pricing, increasing imports, constraining but effective laws related to the environment, health and safety and price controls lead to concerns which generated pious laws stating non-fuel policy and authorizing studies but resulting in ineffective implementation. Several commissions, reports by the Secretary of Interior and even the President have led to many recommendations but little or no action. No single comprehensive policy could solve problems which are diverse, commodity specific and not categorizable (Landsberg 1982, 1983). Thirteen laws administered by 27 agencies regulate or affect minerals and materials. Political instability created by communist regimes in Southern and Central Africa jeopardized sources of critical imported materials. This situation led to a Resource War mentality. It was feared that the U.S.S.R. was seeking to control this area and exclude the United States from resources (Vogely, 1980). The success of the Organization of Petroleum Exporting Countries with a petroleum cartel led to fears of an Organization of Minerals Exporting Countries which might create more cartels and/or make the existing ones more effective. Economic needs of developing countries required export to maintain employment and balance of payments have led to world surpluses, weak markets, low prices, and large loans from the World Bank which have under- mined U.S. industry (Landsberg, 1982a). Un- cooperative environmental laws, obsolete facilities and non-competitive costs have led to shipping U .S. ores to other countries for processing into ingot and bars which are imported back to the United States. Yet massive internal turmoil has interrupted supplies, and led to un- certain availability and higher prices. This situation could happen again. Included in this category of critical materials with uncertain sources are metals required in the manufacture of military aircraft, which has led to concern regarding the defense industry base (Morgan 1983). Remedies have been proposed which include: updated stock piles, material substitution, international cooperation and coordination, foreign policy aimed at resolving racial and national stresses in South and Central Africa, relaxing U.S. environmental and public land regulations and action under the Defense Production Act (Goth 1982). The President's report (1983) to Congress has stated a national materials policy which recognizes: that materials play a critical role in our economy, defense, and standard of living; that public lands contain a vast untapped mineral wealth; that the role of government is to identify mineral issues and act on them; and that there is a need for long term high potential pay off research (Bureau of Mines 1983). There is a serious question as to whether or not a comprehensive national mining, minerals, and materials policy is feasible let alone necessary. One solution is to abandon the attempt at comprehensiveness and to target specific is- sues with realistic policies (Comptroller General 1979). In the following sections, the major studies of the 1970s will be reviewed, major issues yet to be faced will be identified, the principles involved in these resolutions will be reviewed,

Jan 1, 1985

By C. J. Bise

Continuous mining accounts for about 69% of the nation's underground coal production. This level is not expected to change much in the near future. This is because continuous mining represents the primary means of under- ground coal production. It is also the primary means of driving development entries for underground coal mines, including longwall mines. The continuous miner worksite contains many characteristics that can lead to personnel accidents. It continues to be an area of concern for mine managers, safety engineers, and training coordinators. In an effort to assist mine management in attempts to reduce the number of accidents and injuries sustained in this area, this paper presents a loss-control-based, non-intrusive strategy for conducting safety evaluations at continuous miner worksites.

Jan 1, 1991

By K. E. Livo, D. H. Knepper

Modern remote sensing provides a means for locating and characterizing exposed mineralized systems in many parts of the world. These capabilities are non-invasive and help target specific areas for more detailed exploration. An example of how remote sensing technology can be used is evident from a study of the Questa Mining District, New Mexico. Analysis of low spectral resolution data from the Landsat Thematic Mapper satellite system clearly shows the region-al distribution of two broad mineral groups often associated with mineralized systems: clay-carbonate-sulfate and iron oxides-iron hydroxides. Analysis of high spectral resolution data from the Airborne Visible and Infrared Imaging System (AVIRIS) shows the occurrence and distribution of many individual mineral species that characterize the pattern of hydrothermally altered rocks in the district.

Jan 1, 2004

By Warfield Garson

Few, if any, of the non-ionizing radiation health hazards to be found in either surface or underground coal mining are uniquely different because of their being found in the work environment. Hence, they can be considered generally for their bio-effects on the worker when found in the mining work environment. The same may not be said, however, for the lack of non-ionizing radiation and its bio-effects, particularly as it relates to underground coal mining. The term "non-ionizing radiation" refers to various forms of electromagnetic radiation of wavelengths longer than those of ionizing radiation. As the wavelength gets longer the energy of electromagnetic radiation decreases. Therefore, all non-ionizing forms of radiation have less energy than cosmic, gamma, and X-radiation. In order of increasing wavelength, non-ionizing radiation includes ultraviolet, visible light, infrared, microwave, and radiofrequency radiations. The energy frequency and wavelength range of both the ionizing and non-ionizing electromagnetic forces are shown in Table I. To convert the wavelengths of various radiations to Ångström units, one multiplies millimicrons by ten. In a vacuum, all electromagnetic radiation has the same velocity, namely 3 x 1010 centimeters per second. The natural source of radiant energy here on earth is our sun which emits radiation continuously over a wide spectrum. This radiation on average reaching earth ranges from 290 nm in the ultraviolet range to over 2,000 nm in the infrared range with a maximum intensity of about 480 nm in the visual range. You will note this falls into the visible blue wavelength and accounts for our blue sky and blue ocean and deep water effects. We are all familiar with the fact that the passage of solar radiation through the atmosphere to the earth changes the spectrum considerably because the atmosphere absorbs and scatters many of the sun's rays. The ozone in the upper atmosphere absorbs the shorter ultraviolet wavelengths and water vapor absorbs some of the infrared wavelengths. Smoke, dust particles, gas molecules and water droplets scatter the rays, especially those of shorter wavelengths. In addition to the sun, every gas, liquid or solid object at a temperature above absolute 0° radiates energy. Solid objects emit almost continuous spectra. At low temperatures only radiation of the longer wavelengths in the infrared range is emitted, but as the temperature of the object is increased, more and more of the shorter wavelengths are added. This fact is most readily demonstrated by heating a piece of steel. When a piece of steel reaches a temperature of about 1,700° Fahrenheit, it gives off radiation at the red end of the visible spectrum and appears dull red. As the temperature is further increased, the shorter rays are also emitted, until at about 2,100°F, the metal appears white, due to the emission of wavelengths throughout the entire visible range. Gasses, on the other hand, when heated emit radiant energy only at certain wavelengths, which are characteristic of their chemical structure. This latter fact is of importance in underground coal mining as high intensity gas and vapor lamps are becoming more and more utilized for illumination in underground coal mining. The biologic effect of non-ionizing radiation exposure depends upon the type and duration of exposure and on the amount of absorption by the miner. The effects of this radiant energy on the miner fall into four distinct types: (1) the heating effect of infrared radiation, (2) the effect on the eye of visible radiation, (3) the effects of ultraviolet radiation, and (4) the growing potential effects of the misuse of microwave radiation. Each non-ionizing type of radiation will be considered individually. ULTRAVIOLET RADIATION The sun is the major source of ultraviolet radiation, which is of concern in open pit and surface mining at certain seasons and in certain climes necessitating protection for the surface miners under those conditions; nonetheless, there are some man-made sources such as electric arc lights, welding arcs, plasma jets, and special ultraviolet bulbs for illumination underground that demand surveillance in the underground environment to be aware of whether the miners are at risk above the threshold limit values allowable. Since ultraviolet radiation has little penetrating power, the organs that are affected are the skin and the eyes. Ultraviolet radiation is strongly absorbed by nucleic acids and proteins, and the effects in man are largely chemical rather than thermal. Short-term effects on miners include acute changes in the skin. These are of four types: (a) darkening of pigment, (b) erythema (sunburn), (c) increase in pigmentation (tanning) and (d) changes in cell growth. Ultraviolet radiation also causes acute effects on the tissues of the eye. Overexposure can lead to keratitis, inflammation of the cornea, and conjunctivitis. Long-term effects of ultraviolet exposure include an increase in the rate of ageing of the skin with degeneration of skin tissue and a decrease in elasticity. Late effects of ultraviolet on the eye include the development of cataracts. The most serious chronic effect of ultraviolet exposure is skin cancer. Ultraviolet radiation effects are increased by some industrial materials and drugs. After exposure to such compounds as cresols, the skin is exceptionally sensitive to ultraviolet radiation. Photosensitivity reactions occur after exposure to a variety of other chemicals and drugs including dyes, phenothiazines, sulfonamides, and sulfanylureas. On the other hand, we must remember that ultraviolet radiation has an important role in the prevention of rickets. Vitamin D is produced by the action of

Jan 1, 1981

By William H. Moore

Many of the gravel deposits in Mississippi which range in age from Mississippian to Recent are being exhausted. Particularly in southern Mississippi the supplies will become very short in the near future and some use of sand will have to suffice. All methods of exploration for sand and gravel are presently being used in the State and this will be of some assistance in finding other deposits. A good supply of material for expanded clay aggregates is present in the State and will be sufficient to supply the needs of this segment of the construction industry for years to come. Crushed stone has been a minor contributor in years past and will probably become no more important in the future.

Jan 1, 1979