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By R. H. Grau, C. D. Taylor, A. L. Martikainen

Utilization of belt air in underground coal mines has been discussed extensively during the last decade. The Final Report of the Technical Study Panel on the Utilization of Belt Air and the Composition and Fire Retardant Properties of Belt Materials in Underground Coal Mining formed by the Mine Improvement and New Emergency Response (MINER) Act of 2006 recommends research on leakage, use of booster fans, and escapeway safety. This paper discusses the role of ventilation modeling in evaluating primary escapeway pressurization in a three-entry development system to improve emergency escape in a coal mine using belt air. The intake entry of the National Institute for Occupational Safety and Health (NIOSH) Bruceton Experimental Mine was pressurized using a 1.1-m (42-in.) diameter, 37 kW (50 hp) fan. The work details air movement in the simulated three-entry system and the resulting leakage patterns. Three mine ventilation software packages were compared to analyze their performance in predicting the airflows and leakage conditions with different fan settings. NIOSH researchers found that the measurement results correlated well with the results of modeling.

Jan 1, 2010

By Jean E. Kiel, Rob Dorey, Dirk J. A. van Zyl

1.1 INTRODUCTION This chapter seeks to provide an overview of important factors involved in the implementation of heap leach technology as a vehicle for gold extraction from its ores. Toward this end, brief discussions of the various elements important to this process are presented here. Topics covered in this chapter include a brief history of the process; basic chemical reactions responsible for the process ; characteristics of ores amenable to heap leaching; location of the greatest concentration of heap leach projects in the U.S.; heap leach components, methods, regulatory/permitting considerations; and economic considerations. Most of these subjects are treated at much greater length in subsequent chapters. Thus, this chapter serves as a summary for those which follow, in addition to providing the reader with a feeling for those topics which may be of most immediate interest. 1.1.1 History of the Process Modern Day Precious metal heap leaching technology has developed over the past decade, although the principles of heap leaching per se, as well as those of gold extraction through cyanidation have a long history (see discussion below). However, it is in the past 10 years that heap leaching has developed into an efficient method of treating oxidized gold and silver ores. It has proven to be both an efficient way to extract precious metals from small, shallow deposits, as well as an attractive way to treat large, low- grade, disseminated deposits. Heap leaching has several advantages compared to conventional milling (i .e., crushing, grinding, and agitation leaching). In general, these advantages include simplicity, lower capital and operating costs, shorter start-up times, and less intensive environmental regulatory concerns. A possible disadvantage of currently existing heap leach technology is a potentially lower percentage of metal extraction being obtained from the ore than would be the case with conventional milling (Potter, 1981; Hiskey, 1985; and Thorstad, 1987) The actual principle of heap leaching has a long history as inferred previously. For example, mines in Hungary recycled copper-bearing solutions through waste heaps in the mid-sixteenth century (Hiskey, 1985), and Spanish miners percolated acid solutions through large heaps of oxide copper ore on the banks of the Rio Tinto around 1752. By 1900, leaching operations were employing such techniques as leach/rest cycles to maximize copper recovery (Taylor and Whelan, 1942; Thorstad, 1987). Copper dump leaching is currently

Jan 1, 1988

By Éder Domingos Oliveira, Carlos Antonio Morais, Ruberlan Gomes Silva

The objective of this work was to assess the influence of parameters such as residence time, solid content, and temperature in a process route towards purified rare earth liquor which could be adequate to produce marketable rare earth products. The steps of the process route proposed in this study comprised water leaching of a sulfated rare earth ore and removal of impurities through the purification of the rare earth sulfuric liquor, which is the product of the water leaching step. The sample used in the water leaching experiments was a sulfated rare earth ore produced by the reaction of a beneficiated rare earth ore with sulfuric acid followed by roasting at 700 °C for 2 h in a muffle furnace and cooling at 20 °C. The water leaching experiments showed that the best condition comprised a residence time of 30 min, temperature of 20 °C, and solid content of 10% w/w, resulting in a recovery of 71.3% of the rare earth elements (REE) and a lower impurity extraction, e.g., only 15.0% of Fe, representing the main impurity in the rare earth ore. Even when presenting low amounts of impurities, the rare earth sulfuric liquor still needed to be purified before it can be used in the production of marketable rare earth products. In the study, the rare earth sulfuric liquors were purified in two consecutive neutralization steps, first by dosing the limestone pulp to pH up to 3.5 and secondly by adding the lime pulp to raise the pH from 3.5 to 5.0. The application of two consecutive purification steps at 20 °C resulted in the highest overall REE recoveries (65.4%) throughout all the steps of the process, being 71.3% in the water leaching, 99.6% in the partial purification with limestone pulp, and 92.1% in the purification with lime pulp at 20 °C. Under this condition, there was a total elimination of Fe, P, and Th and a significant reduction in the Al, U, and sulfate concentrations in the purified rare earth liquor. The purified rare earth liquor attained through the experiment is expected to be amenable to be used in the production of marketable products due to the lower impurities/REO mass ratios.

By Zhongxue Li, Baolu Zhou, Yiqing Zhao

"Rare earth elements (REEs) are a kind of new materials which have excellent optical, electrical and magnetic properties, and they play an important role in the development of high technology and green energy industries. With abundant reserves and a wide range of REE type, rare earth industry has a rapid development in China in recent years. However, environmental issues associated with REE exploitation have severely restricted the sustainable development of rare earth industry in China. At present, literatures on the externalities of REE exploitation are very limited, especially in China. This paper builds an evaluation model based on life cycle evaluation to estimate the external costs of REE exploitation at Bayan Obo. The results show that the external costs for producing one metric tonne of rare earth oxides (REO) in Bayan Obo was CNY 34739 in 2013, the external costs of waste gas, waste water, radioactive substance, REE resource depletion, and land occupation are CNY 14945, 12515, 1400, 3199, and 2680, respectively. Waste gas and water constitute about 79% of the total external costs. The internalization of the external costs would reduce the financial profit of Northern Rare Earth (Group) by 18%. This study has taken into account only those externalities whose market values can be estimated, and therefore the external costs of REE exploitation in Bayan Obo is likely to be underestimated. The results fill the gap in literature and provide further understanding on the external cost of REE exploitation.Introduction / Background Along with increasing concern about environmental pollution problems caused by the usage of fossil fuel and the shortage of fossil energy, a transition has occurred where development has moved toward green and renewable energy sources with less pollutant emissions (Stegen 2015). Rare earth elements (REE) are a group of important raw materials for these trends since they have unique magnetic, electronic and optical properties, and thus make them widely used in making high-performance magnets and energy saving lamps (U.S. DOE 2010). In addition, REE are crucial for manufacturing of widespread high-tech applications in medical, defense and electronic industries. Many countries have made medium-term and long-term plans for the development of their REE industries, and the annual growth rate of global REE demand is expected to increase by 6% by 2020, and reach about 170,000 metric tons of rare earth oxides (REO) by 2020 (Rollat et al 2016)."

Jan 1, 2017

By J. Szarkowski

"INTRODUCTION The Butte district of Montana is well-known as one of the biggest historic producers of copper in the world. It is also a classic example of a porphyry Cu-Mo system that has been overprinted by zoned, polymetallic (Cu-Zn-Pb-Ag) lode mineralization. After copper, silver was the next most important metal mined from Butte, with over 700 million ounces of total Ag production between 1880 and the present day. Although many papers have been written on the mineralogy of the early porphyry Cu-Mo mineralization and the high-grade Cu-rich lodes in the center of the district, relatively little information exists on the mineralogy of silver in Butte. The purpose of this paper is to summarize past and present silver production trends for the district, and to combine previously published work with new research to examine the mineralogy of silver in the Butte mining district. BUTTE HISTORIC SILVER PRODUCTION According to a recent USGS compilation1, Butte is one of the most Ag-rich porphyry deposits in the world, both in terms of average Ag grade (8.6 g/ton) and total production + reserves (Fig. 1). It is also the 2nd biggest Ag-producing mining district in the U.S. (after the Couer d’Alene district, Idaho). Annual silver and copper production data for the Butte district, compiled from various sources2,3,4, are summarized in Figure 2. Peak production of Ag and Cu was in 1917. While Ag production gradually declined in the ensuing decades, Cu production remained strong until the years leading up to the closure of the Berkeley Pit in 1982. In 1984, mining of the nearby Continental Pit resumed under a different operator, and continues to the present day. The Continental mine produced an average of 35,000 metric tons Cu and 575,000 oz Ag per year between 1984 and 20044. These figures do not take into account a period of mine closure in 2001-2003 due to an unexpected hike in utility prices. The long-term decline in Ag/Cu ratio of ore mined in Butte (Figure 3) is due to several factors, including: 1) changes in metal prices; 2) a downwards decrease in Ag/Cu ratio of most of the lodes with depth below surface; and 3) a shift in mining methods from selective underground mining of high-grade veins to open-pit mining of the bulk rock."

Jan 1, 2016

By Paul C. Miclea

With the growing urban population and the concern for traffic congestion and pollution (emissions control), public transportation is becoming more and more attractive to both city dwellers and managers. To gain access to the central area of the city, the sub- way remains the most viable alternative, despite its higher cost when compared to above ground or elevated transportation systems. There are relatively few regulations and criteria for subway ventilation, particularly when compared with mine ventilation. The main document that provides guidance and general recommendations for subway ventilation and environmental control is the Sub- way Environmental Design Handbook, published in 1976 (2nd edition) by the U.S. Department of Transportation, Office of Re- search and Development. Many of the subway systems in existence today have been designed and built with ventilation features adequate for normal train operation, but their design does not consider stringent criteria for such emergency conditions as a train fire in a tunnel. The National Fire Protection Association's Standard for Fixed Guideway Transit Systems known as NFPA 130 as well as the ASHRAE Handbook - HVAC Applications (1995) provide specific design and operation requirements for subway ventilation systems. Some of the existing, old subways are upgrading their ventilation systems to comply with the new regulations. The ability of a particular ventilation system design to provide adequate ventilation during normal and emergency conditions can be evaluated using computer modeling and simulation techniques. A train fire will cause a sudden change in the tunnel ventilation pattern by adding an unsteady and fast-growing source of heat. The hot air and gasses created by a fire will tend to flow uphill, possibly against the normal flow, producing a 'backlayering effect." To prevent this effect from happening, enough ventilation must be provided and the governing criterion to establish the required airflow is called 'Critical Velocity." Several software packages are available for special applications on tunnel and station ventilation as well as to model the spread of smoke and heat in case of a major tunnel fire, using Computational Fluid Dynamics. This paper presents the current issues in subway ventilation, as shared by the public transit community around the world, together with modern alternative design concepts vis-à-vis the more stringent emerging Fire-Life Safety criteria. Examples of recent studies and ventilation systems design are provided.

Jan 1, 1997

By C. Villa Diniz

It is proposed that battery grade Mn02 can be produced directly from a manganese ore from Azul Mine in Brazil, by leaching with HCI to remove heavy metals selectively. We are working to find a way of selectively separating Cu, Ni, Co, Pb and Fe from the resulting acidic manganese chloride solution, to detoxify it and produce marketable chloride solution. Chelating ion exchange resins are proving more promising for this separation than solvent extraction with commercially available reagents. Results from batch and column ion exchange tests that characterize the behavior of copper, nickel, cobalt, lead and iron are reported.

Jan 1, 1999

By M. Li, J. K. Thompson, A. S. Azman

"Powerful mining systems typically generate high-level noise that can damage the hearing ability of miners. Engineering noise controls are the most desirable and effective control for overexposure to noise. However, the effects of these noise controls on the actual hearing status of workers are not easily measured. A tool that can provide guidance in assigning workers to jobs based on the noise levels to which they will be exposed is highly desirable. Therefore, the Office of Mine Safety and Health Research (OMSHR) of the National Institute for Occupational Safety and Health (NIOSH) developed a useful tool to estimate the hearing loss due to occupational noise exposure in a systematic way and evaluate the effectiveness of developed engineering controls. This computer program is based on the ISO 1999 standard and can be used to estimate the loss of hearing ability caused by occupational noise exposures. In this paper, the functionalities of this software are discussed and several case studies related to mining machinery are presented to demonstrate the functionalities of this software. INTRODUCTIONPeople regularly exposed to noise can develop hearing loss at different levels of severity depending on a number of factors. The resultant hearing loss can affect one’s ability to understand speech, learning, acoustic signal perception, or appreciation of music. Hearing loss caused by overexposure to noise has long been recognized in literature. However, it still does not get serious attention by those working in noisy environments because the loss of hearing ability is a gradual process and workers are often unaware until the damage becomes an apparent problem. In the United States, occupational hearing loss is one of the most common work-related illnesses. Depending on the definition of exposure and impairment, in 2012 the National Institute for Occupational Safety and Health (NIOSH) estimated that there are between 5 and 30 million workers in the U.S. who are exposed to noise levels at work that put them at risk of hearing loss.4 In the mining industry, noise-induced hearing loss (NIHL) is particularly severe due to the fact that heavy-duty machinery is widely used to improve production efficiency, and this machinery can generate much higher-level noise than the permissible level defined by regulation. As a result, the mining sector has the highest prevalence of hazardous workplace with high noise exposures (76%) among all industrial sectors."

Jan 1, 2015

By S. M. Khandrika

Most of the coal presently used by the utility industry is cleaned at preparation plants employing wet processes. While water is the mainstay of coal washing, it is one of the least desirable components in the final product causing a reduction of the heating value as well as handling difficulties. Currently available dewatering techniques are inefficient for dewatering very fine coal (minus 325 mesh). The US coal industry has expressed serious concern about utilizing advanced cleaning processes such as column flotation because an efficient and economical dewatering process is not available.

Jan 1, 1992

By C. Zhou, C. C. Jobes, J. H. DuCarme

"Magnetic proximity detection systems (PDSs) are used with continuous mining machines (CMMs) to protect miners from striking and pinning accidents. Generators are used in a PDS to create magnetic fields covering the space around a CMM. The PDS determines the proximity of a miner relative to the CMM based on the magnetic flux density detected by a miner-wearable component (MWC) and simultaneously alerts the miner and stops the motion of the CMM if the miner is within a proximity that creates a striking hazard. A stable magnetic field is essential to the accuracy of the proximity calculations performed by the PDS. This paper presents the results of a systematic study of the magnetic influence of two types of steel structures found near a CMM—the body of the CMM itself and the wire mesh used for roof and rib control. The results show that the steel of the CMM body can change the magnetic field distribution and also alter electrical parameters of a PDS by changing its generator current. The study also shows that, depending on the distance between the wire mesh and a generator, the magnetic field can also be altered. INTRODUCTION Continuous mining machines (CMMs) can be up to 10 m (33’) in length and more than 3 m (10’) in width. These machines perform the coal cutting operations in underground room-and-pillar coal mines. Accidents during CMM operation accounts for an average of 250 injuries every year, and 43 miners have been killed by striking or pinning accidents involving CMMs in the United States from 1984 to 2015.Because of these fatalities and injuries, the Mine Safety and Health Administration (MSHA) promulgated a regulation in 2015 that requires the use of proximity detection systems (PDSs) on all CMMs with the exception of full-face machines (Mine Safety and Health Administration, 2015). Currently, there are five different proximity detection systems that MSHA has approved as permissible for use in U.S. underground coal mines (Mine Safety and Health Administration, 2013). All of these PDSs rely on a miner-wearable component (MWC) to detect the generated magnetic fields that PDSs produce around a CMM (Schiffbauer, 2002). These systems use the magnetic field strength readings in terms of magnetic flux density from the MWC to determine whether a miner is at a safe distance from the CMM. A stable magnetic field is essential for the accuracy of a PDS."

Jan 1, 2018

By C. E. Davis

The Jamaica Mining Legislation requires the bauxite companies operating in the island to reclaim all mined-out lands (except those legitimately excluded) to the level of agricultural or pastoral productivity, which existed prior to the commencement of mining. If it is not possible to reclaim a mined-out area the companies are required to reclaim an equivalent area of some other land which had not previously been used for agricultural purposes, or alternatively, pay to the government the sum of $120 (US) for every acre of land mined in the particular sector. In the seventeen years since the programme commenced the companies have in general chosen to reclaim most of the mined-out lands, rather than the cheaper alternative. However, the ultimate success of the programme will depend not only on actual reclamation per se but moreso the productivity of the rehabilitated lands. There are a number of reasons why the accent has to be placed on productivity of the lands. The first is that Jamaica is a small country (4,450 square miles) with a population of nearly 2 million people. Because of its mountainous terrain it is estimated that only 35% of the land area is cultivable in crops and pastures; hence this limited area, as well as that which can be reclaimed, must be made highly productive in order to support local and export demands. The Mining companies own over 200,000 acres of land, and of this acreage, it is conservatively estimated that about 75,000 will be affected by mining and will be reclaimed. As such, the use of the land after mining can have an important bearing on Jamaica's future agricultural productivity. The second reason is that a significant amount of the land now owned by the companies was purchased from thousands of small

Jan 1, 1972

By Justine Ealy, Daniel Yang, Christina Foster

Maintaining stable high walls can be a challenging task. Complex geological and structural features, alteration zones, rock mass properties, and hydrogeological conditions must be well understood to design a safe mining environment. Economic considerations must also be taken into account as the mine operator must provide ore deliveries and protect reserves. However, even when good engineering practices are followed, and proper blasting and mining techniques are implemented, slope movements may still occur. When these slope instabilities are minor, the mine is often able to continue operations with minimal impacts on safety or production. When these occurrences are excessive and coupled with high rates of movement, a robust monitoring system is crucial to continuing mining activities while protecting personnel. This paper summarizes the approach an open pit mine in Nevada took as excessive and rapid high-wall movement was experienced in an integral area. Creative mining approaches, combined with slope monitoring radar technology, were utilized to maintain safe and successful mining activities despite active movement that exceeded an average velocity of 30 inches per day.

Feb 1, 2024

By Gregory M. Rumbaugh, Christopher Mark

"The proliferation of unconventional gas well development in the Northern Appalachian coalfields has raised a number of mine safety concerns. Unconventional wells, which extract gas from deep shale formations, are characterized by gas volumes and pressures that are significantly higher than those observed at many conventional wells. The gas is composed largely of methane as well as other hydrocarbons. Hundreds of planned and actively producing wells penetrate protective coal pillars or barriers within active mine boundaries, including chain pillars located between longwall panels. Gas released from a well damaged by mining-induced ground movements could pose a risk to miners by flowing into the mine atmosphere. The mining-induced ground movements that may cause well damage include conventional subsidence, non-conventional subsidence (e.g., bedding plane slip), pillar failure, and floor instability. This paper describes the known risk factors for each of the four failure mechanisms. It includes a framework that can guide the risk assessment process when mining takes place near gas or oil wells.INTRODUCTIONSouthwestern Pennsylvania has served for centuries as a producer of coal, oil, and natural gas. Coal mines were first developed in the Pittsburgh Coal Seam in the 1760s, with the first recorded mine in 1761 being the Fort Pitt Mine (Edmunds, 2002). Natural gas was introduced to the region when the Haymaker Well in Murrysville, Pennsylvania experienced a blowout on November 3, 1878. Although it was originally drilled prospecting for oil, it produced an estimated 30 million cubic feet per day of natural gas. Without well controls or pipeline infrastructure in place, it burst into flames and lit the night sky for over a year. Soon after, the Penn Fuel Company continued development of the Murrysville gas field and is credited with making Pittsburgh, Pennsylvania the first major city in the U.S. to have natural gas supplied for home and industrial uses. “Natural gas is king in Pittsburgh,” proclaimed an October 18, 1885, article in the New York Times headlined “Value of Natural Gas, Its Use Clarifies the Atmosphere at Pittsburgh” (AOGHS, 2018). By the early 1900s, coal, oil, and natural gas production had reached the southern extents of Pennsylvania in Greene County. The county had first produced oil in 1886, and shortly after began producing natural gas in 1890. By 1906, over 1,300 wells had been drilled (Stone and Clapp, 1906)."

Jan 1, 2019

By S. G. Britton

Microcomputer analysis has long been a technique for engineering professionals to improve the theoretical and practical design of continuous mining systems. Such work has been typically composed of modeling observed events and then introducing a variety of known elements with predicted results to compare against the results of the model. Programs written in BASIC, Cobol, Fortran, or other language dominated such efforts. These programs have taken years to develop and prove out. This paper explores a new management tool used at TMC on a daily basis to track and improve continuous mining systems through the use of microcomputers and Lotus 1-2-3 software. By analyzing data provided by section foreman, shift foreman, and maintenance personnel against predetermined goals, new production targets are developed, weaknesses in the current mining systems are identified, and the results of changes are measured. The results of this system on the productive output of TMC systems are on the order of ten percent improvement.

Jan 1, 1991

By Earl Cook

Introduction Men like physical power because it gives control over nature and over other men. Physical power comes in two common forms: explosive and non-explosive. In both forms, the most powerful devices yet invented make use of nuclear energy: on the one hand, the hydrogen or fusion bomb, and, on the other hand, a nuclear power plant. For some nations, nuclear power offers a measure of independence not otherwise available in a time of diminishing and unevenly allocated fossil fuels. Consequently, it has great attraction. Unfortunately, the application of nuclear energy (especially fission energy) to either explosive or electrical power entails a singular risk, that of injury from ionizing radiation, both natural and induced; this risk is found in all stages of the nuclear-fuel cycle, from mining of fissionable materials to the disposal of wastes produced in the "burning" of nuclear fuels. The health costs of nuclear power were not fully assessed in the early stages of the development of nuclear technology and some of them were not properly guarded against, either in the USA, which led the world into the nuclear age, or in Canada, which followed an independent path. What I shall do in this paper is to sketch the history of nuclear regulation in our two countries, to point out what I consider similarities and differences, and to suggest that regulatory history, as perceived by a concerned public, has a great deal to do with what is possible today and probable tomorrow, in other words, with public acceptance or rejection of the nuclear option. The U.S. situation As we sow, so shall we reap. In the USA, further expansion of the nuclearpower industry has been almost stymied by government actions that reflect mounting public concern. There is no national storage facility for spent reactor fuel and it has been decided not to reprocess it; consequently, existing power plants are about to choke on their own wastes. Since the Three Mile Island accident, no new nuclear plants have received operating licenses, although several are ready to start up. The uncertainty of future government action has caused the abandonment of plans for a number of new nuclear plants. In addition, many research projects related to medicine and agriculture, which produce low-level radioactive wastes, are about to be shut down for lack of licensed disposal facilities. Some would maintain that this situation has come about because of the low benefit-to-cost

Jan 1, 1980

By S. P. Sandoval

In 2002 the Freeport-McMoRan Technology Center undertook research to develop a lower-cost alternative to guar for cathode smoothing in copper electrowinning. The work was conducted at the Technology Center?s SXEW Test Facility located in Morenci, Arizona. Bench-scale copper electrowinning cells were designed and implemented to screen a number of potential polymers for cathode smoothing. These included modified polysaccharide polymers that were nonionic, cationic, and anionic in nature.

Jan 1, 2010

By H. E. Grand

The purpose of this paper is to outline briefly some basic principles of ground- water hydrology that have application in mine hydrology. The development of a mine below the water table pleads for accurate values to answers of hydrology problems. Such problems involve both an inflow of water without adequate drainage facilities and a deficiency of water for the required use. Methods which give acceptable quantitative values for the solution of many ground-water problems depend on rather simple geologic structures, characterized chiefly by isotropic rocks of considerable areal extent. Unfortunately, mining operations are likely to be centered where isotropic rocks are not present. Consequently, methods that attempt to show values of the storage and transmitting capacity of rocks in mining areas must be applied with caution. In spite of complex geology and apparent uniqueness of individual mines and quarries, adherence to some concepts of ground water used by -hydrologists in the study of behavior of wells should be helpful to mine operators, The work of the Ground Water Branch of the U.S. Geological Survey through its history has been confined largely to the study of ground water as a resource, In view of the increasing number of problems relating to drainage of mines, the Branch started an investigation of mine hydrology in 1945 under the direction of W.T. Stuart, Mr. Stuart and other workers are making detailed studies of specific mine areas. In the present paper an attempt is made to synthesize some facts about ground water into usable form for the typical mine operator. Mining operations that extend below the water table disturb the natural hydrologic regimen, Prior to development, the water table slopes away from the site of a mine in at least one direction, but as soon as development begins and water is removed from the mine, the mine becomes the apex of a depressed cone in the water table, causing a convergence in the flow of water toward the mine. The behavior of the cone of depression, as it tends to deepen and increase in areal extent when the mine deepens, is related to the rate of withdrawal of water necessary to keep the mine dry. The significance and nature of the cone of depression in the vicinity of pumped wells has been studied by ground-water hydrologists for years, but the cone caused by pumping water from mines has generally been less systematically appraised.

Jan 1, 1958

By V. Svalbonas

The process of grinding mill quality assurance brings with it associated truths and myths. When the mill quality assurance process took its first great steps forward in the late 1970s and early 1980s, they were in response to the conditions existing, in our industry, at those times. In the late 1990s, we are faced with different conditions, and problems, and need fresh solutions. Yet the system developed for the early 1980s has produced no new approaches for the late 1990s, becoming instead more hardened and entrenched. This lack of development and actual resistance to research is now costing the industry significant amounts of money in late start-ups and useless scrap loss.

Jan 1, 1999

By Sergio Flores, Nate Long, William Hodder, Phil Rhodes, Tim McQueary

The Surface Water Supply Project Segment B3 is a 4 miles section of tunnel that will run East- West in Houston TX, from Hopper St to I-45. The tunnel will be mined by using a 128" Dia refurbished 1987 Lovat Tunnel Boring Machine capable of operating in Open or EPB mode. The tunnel will be temporarily supported with ribs and lagging and a 96" Dia pipe will be grouted into place. All four miles of this project are within Petroleum Pipeline Easements. The project includes seven shafts, 2000' of tunnel in potentially petroleum contaminated ground, crossing the Hardy Toll d, I-45, the nion Pacic ailroad ight of Way and multiple oil and gas pipeline crossings. This paper summarizes the planning and drive performed to date.

Jun 23, 2024

By R. A. Thomas, C. D. Litton

"The objective of this study was to develop a laboratory-scale method to rank the ignition and fire hazards of commonly used underground mine materials and to eliminate the need for expensive large-scale tests that are currently being used. A radiant panel apparatus was used to determine the relevant thermal characteristics of the materials: time to ignition, critical heat flux for ignition, heat of gasification, and mass loss rate. Three thermal parameters, TRP, TP1, and TP4, were derived from the data, then were developed and subsequently used to rank the combined ignition and fire hazards of the combustible materials from low hazard to high hazard. The results compared favorably with thermal and ignition hazards of similar materials reported in the literature and represent a simpler approach to quantifying these combustible hazards. INTRODUCTION The potential fire hazard from combustible mine materials is a major concern that can impact the safety of mine workers. Combustible materials tend to be solids and within this category there exist degrees of flammability and fire resistance. These materials may be readily ignitable or they may be able to withstand high temperatures and high heat fluxes. Presently, no simple methodology exists to assess these possible fire behaviors and quantify the resultant fire hazards. Thus, better knowledge of the thermal properties and chemical characteristics of combustible materials is of great importance to the safety of mine workers. Tewarson [1994] developed a methodology which he subsequently used to evaluate the ignition and fire resistant properties of combustible mine materials, but these efforts are more than 20 years old, and do not include many of the new materials used in mines today. The standard practice that has evolved for a combustible material to be approved by the Mine Safety and Health Administration for use in underground coal mines is to conduct extensive and costly large-scale experiments on each new material that is used in a particular mine operation. Results of such tests provide pass/fail answers to the questions of a material’s flammability or fire resistance, yet they provide little, if any, information that will lead to a better understanding of the basic mechanisms involved. Therefore, there is a need to quantify material flammability properties and to develop a methodology to rank the ignition and fire hazards of commonly used underground mine materials. During the heating and ignition stages of combustible materials, properties such as smolder susceptibility, minimum surface temperature for ignition, thermal conductivity, heat capacity, density, and heat of gasification are known to be important [Apte, 2006]. During the flaming stage, additional parameters, such as the heat of combustion, heat release rate, flame spread rate, yields of soot/smoke, and toxic gas production become more important as the flame is sustained and spreads. In very general terms, the heat flux incident on the surface of a solid combustible not only controls the rate of temperature increase of the local fuel surfaces, resulting in expulsion of fuel vapors that sustain the flaming process, but also the heating of other combustible surfaces that subsequently ignite and spread flame."

Jan 1, 2015