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By John M. Hird

Texas Gulf Sulphur Company's Lee Creek Mine has opened a major phosphate mining district in the Central Coastal Plains of North Carolina (Fig. 1). The ore deposit as it is now known was roughly outlined in 1961 by a Texas Gulf geologist using wire line exploration methods. Slightly uraniferous phosphate materials were detected by a slim-hole gamma ray probe run in numerous farmers' water wells penetrating the formations. A follow-up-core drilling pro- gram determined the economic ore limits to lie in the south central section of Beaufort County beneath 70 feet to 120 feet of unconsolidated sediments. The 50,000 acre deposit is known to contain over two billion tons of phosphate ore amenable to strip mining methods. A part of the deposit underlies several thousand acres of the Pamlico River estuary. The 90 million dollar capital investment plant built by Texas Gulf during 1965-66 included a strip mining operation using a 72-yard walking dragline, a three million product ton per year flotation concentrator, four fluid bed calciners, a sulphuric acid plant (acid for captive use), a phosphoric acid plant, and three solid fertilizer material plants. Shipment to domestic markets is by rail and truck and to over- seas markets by barge to a transshipment terminal at Morehead City, North Carolina. Early mining investigations were conclusive first that the phosphate ore could economically be recovered only by dry strip mining methods, and second that artesian ground waters in the formation (Castle Hayne limestone) underlying the ore would have to be controlled. This report will relate the application of ground water hydrology in depressurizing the Castle Hayne aquifer to facilitate dry strip mining at depths 130 feet below sea level at the Lee Creek Mine.

Jan 1, 1970

By B. Simser, T. Butler, A. Hall

The longterm future of Glencores’ mining operations in the Sudbury basin area of Ontario, Canada likely depends on mining deposits at depths below two kilometres. To gain a better insight into the rockmass response to mining, a geological scouthole program has been implemented at Glencores’ Nickel Rim Deep and Onaping Depth Project to gain insight into rockmass conditions ahead of the devel-opment face. The scouthole program involves drilling long (up to 600 m) subhorizontal boreholes drilled ahead of the development end and collecting data about the rockmass conditions from various geophysi-cal and mechanical tools (in addition to conventional core logging). Once all data has been collected and the borehole is available, seismic sensors are installed up to 450 m down the hole as part of the micro-seismic monitoring program with the leading sensor always located ahead of the development end. The recorded seismic data is used to provide realtime insight into the rockmass response to mining. On May 20, 2017 a flurry of seismicity with a maximum moment magnitude (Mw) of 0.7 occurred causing damage to the ramp heading. Data from the microseismic monitoring system had indicated that conditions at the development end were changing prior to the rockburst. A back analysis of the scouthole data indicated a clear anomaly in the rockmass at the location of the rockburst. The scouthole data also provided sufficient information to suggest that once this anomalous zone was exited, mining conditions would improve. With the microseismic monitoring system providing realtime information from the rockmass, the area was re-habilitated and ramp development continued successfully. Details of the rehabilitation and adjustments to the ramp development are discussed. Some correlations between the scouthole data and recorded micro-seismicity are also presented.

Apr 26, 2022

By Joseph G. Carleton

INTRODUCTION The increasing concern for the environment may well present far more opportunities than problems for those involved in all phases of tunneling. All too frequently in the past, environmentalists and their concerns have been cast in a negative light, as obstacles to be overcome. Often forgotten is the fact that these same environmental concerns have created a rapidly increasing demand for new tunnels. Tunnels for rapid transit projects, clean water supply, and sewage treatment have been given a boost because of environmentalists' concerns about overuse of automobiles, inadequate water supplies, and improper sewage disposal. Concurrent with increasing use of tunnels to help solve or alleviate some of our environmental problems is an obligation not to create new ones in the process. Concerns which we feel responsible tunnel owners, engineers, and contractors should address themselves to include: (1) Minimum energy consumption, both during construction and in operation of the completed project; (2) proper storage and/or disposal of the excavated material; (3) minimum disruption during the construction process - noise, traffic, unnecessarily unsightly work areas, and possible weakening of foundations of nearby structures; and (4) a finished project consistent with community and environmental goals. We are especially concerned about two things. First, the longrun implications of a project -- what's good for a few people in the short-run may be bad for most of the people in the long-run. Cutting corners to save a little money now is false economy. Second, the fact that ultimately we all share the same earth -- its water, air,

Jan 1, 1974

By D. E. L. Zapata, O. J. R. Baena

"INTRODUCTION Mining is a fundamental part of the historical and economic development of a country. In Colombia, this is reflected from pre-Columbian jewelery, to being now one of the first exporters of coal worldwide, in 2017, the Colombian mining sector contributed approximately 6% of GDP (Ministerio de Minas y Energía, 2017). Coal, nickel, gold, platinum, emeralds, limestone, salt, phosphate rock, clays, siliceous sands and to a lesser extent copper, manganese, magnesite, barite, gypsum and various types of ornamental rocks, among others are produced (UPME, 2016). The contributions of mining activity in the economic dimension is more measurable, on the contrary in other dimensions, as the social and environmental, for this, every day there are new proposals and tools oriented to strengthen how to evaluate the contributions in terms of the sustainability and responsibility, with the aim of quantifying, concreting and non-utopian, to improve the life quality of a community and not only to comply with reporting and gaining prestige. Colombia has a generalized increase in the mining sector where the levels of informality and illegality are evident only 10% of mining activity is legal (UPME, 2014), also, the mining sector is accused of human rights violations, high levels of inequality, poverty and the affectation of ecosystems due to bad environmental management, among other situations (ACNUDH Colombia, 2015). This problem has generated rejection to the realization of the mining activity in many places of Colombia. At this point, it is important to clarify this problem is more complex, different actors are involved in this conflict, but it is an evidence that is needed a sustainability model for specific realities such as the Colombian mining. This situation in the current mining activity, is similar to the chemical industry situation three decades ago, because of an extensive problem in relation to repeated work accidents, natural disasters and indications as a highly polluting and unsustainable industry, with the aim of improving, not only this public perception, but also in the way of carrying out the business activity. Thus, in 1985, the Canadian Chemical Producers Association released the Responsible Care Program (RCP) (ICCA, 2015). Being aware that companies were responsible for the affected lives in some way by the operation and needed to improve workers safety, environmental protection and most importantly how legal persons should comply with the law, but go beyond this. RCP is most recognized sustainability initiative in the chemical sector, companies associated are recognized for having high quality standards, continuous improvement, visibility, corporate ethics, environmental and social management (ACC, 2015). In addition, to meeting the objectives is set out the creation of a model that increasing reputational sector levels. This initiative is considered to be a worldwide successful case of reporting corporate responsibility indicators and contributions to sustainability from the industry sector to local development (BASF Group, 2016)."

Jan 1, 2018

By David Hurth

JOHN HAMRIC: Our next topic leader is David Huth, superintendent of sulfuric power generation, DAP, and shipping for IMC-Agrico, Nichols Plant, Mulberry, Florida. With a title like that it's no wonder he believes in empowerment. His topic today is "The Triumphs and Pitfalls of Using Empowerment Techniques." DAVID HUTH: Empowerment and its benefits are a desirable alternative to the traditional management structure. The difference between the two is the amount of decision- making authority and responsibility given to individuals by a supervisor. Just what is empowerment and how does it work? Empowerment is relinquishing to individuals the authority and responsibility to make daily decisions. Can everyone be empowered? What if they make a wrong decision? Will I empower myself out of a job? These are questions that all managers have when they hear the word empowerment. In today's fast-paced and high-pressure business environment, the old way of managing people must be replaced with a new approach. No longer can we, as managers, make all the decisions. The increased work loads due to downsizing, consolidation, and synergies have stretched us too thin. What about our employees? How can we motivate them into the high-performance teams that our companies are demanding? What possibly could satisfy both these issues? The solution to these problems can be solved with the power of employee empowerment. Employee empowerment will not only lessen the load on managers but will build teamwork, motivation, and pride into the employees who work for the managers who use it. American business was rudely awakened in the early 1980s when the Japanese companies not only caught up to American companies but literally flew by them. America was fat, dumb, and happy after World War II. Why wouldn't they be? They had all the factories. Everyone else had to rebuild. So for 40 years American business lounged in the limelight of very little true competition. But times change. Unfortunately, American business did not. Now the cry to perform in the new global economy has come down from the corporate boardrooms. Down through the ranks it has been felt. Guess who is supposed to make it work? But where are all those people who are going to make this rejuvenation and corporate renaissance possible? Many of them are gone-lost in downsizing, synergies, and rightsizings

Jan 1, 1998

By Weiguo Xie, MARK LAPUTKA

The pyrometallurgical industry plays a vital role in producing metals for our modern life. With growing demand for metals and declining grade of mineable ore, innovations become critical for many mining companies. This has given rise to the need for a review of recent improvements to the pyrometallurgical industry in terms of analytical measurement techniques, process and equipment improvements, and computer-based modeling/simulations. Because many of these innovations tend to be applied to a wider scope of metals, not restricted to a specific metal, we studied the broad applications of many improvements to a wide range of metals. We found that the challenge of a lack of robust measurement techniques under high-temperature conditions within a furnace hinders optimization of a pyrometallurgical process. Some future opportunities in the pyrometallurgical industry on analytical measurement techniques, computer modeling, and processes and equipment were also outlined and discussed.

By J. S. Hu

FTIR spectroscopy has been used for the characterization of adsorbed oleate at the fluorite surface. It has been found that modest changes in the adsorption density at high temperature and high oxygen potential do not provide a satisfactory explanation for the significant increase in the hydrophobic character of the system under similar conditions. Rather, FTIR spectroscopic measurements suggest that chemical interaction between adsorbed oleyl groups occurs at high temperature and/or oxygen potential and accounts for the increased hydrophobicity. Specifically, the intensity of the =CH bond of the adsorbed oleate diminishes at high temperature and/or high oxygen potential. Such a phenomenon was not observed in control tests with the calcium oleate soap. For extensive reaction at the fluorite surface, the presence of a new surface species has been identified. These results indicate that the fluorite surface catalyzes an oxidation and/or polymerization reaction between adsorbed oleyl groups which results in a more hydrophobic structure at the fluorite surface.

Jan 1, 1986

By Dan Ifrim, Andre Solecki

Tunneling could be a major challenge to tunneling contractors as tunneling operations can be seriously affected by the Tunnel Boring Machine (TBM) performance. Specifying the appropriate TBM methodology, selection of systems and features, is critical for managing tunnel risks and contribute to successful tunneling project. The paper analyzes tunneling records from the recently completed City of Toronto’s Ashbridges Bay Treatment Outfall tunnel project and underlines the righteous selection of the TBM type and associated TBM systems in achieving good advance rates during tunnelling and managing project risks. The paper intends to draw attention of a few aspects of TBM technical specification importance and highlight the lessons learned from this process.

Jun 13, 2023

By MARK J. VANARELLI

Estimating ground-water inflows in rock deep tunnels is critical to the safety of personnel constructing the tunnel and the cost of construction. This paper presents two case studies, including the Chattahoochee and Nancy Creek tunnels, for estimating steady-state ground-water inflows into deep rock tunnels. Statistical methods were applied to packer test data obtained from exploratory borings during geotechnical site investigations, and a semiempirical procedure was used to estimate ground-water inflows. The Chattahoochee and Nancy Creek tunnels are deep rock tunnels that exhibit radial flow conditions. For the radial flow condition, a statistical analysis presented in this paper indicates that the semiempirical procedure works well; however, variations in the procedure and/or an insufficient amount of testing could lead to underestimations of the inflow quantities. Modeling using Monte Carlo simulations was observed to be an effective tool for removing data distribution irregularities and incorporating high-end permeability data to derive reasonable ground-water inflow estimates.

By S. B. Bhagwat

The United States has abundant coal resources that could last at least another century. and probably longer at present consumption rates. Geographically, the coal resources are distributed over the entire nation including Alaska, although there are no coal deposits in the highly populated areas on the two coasts. This allows free access to the coal, but makes transportation more expensive. Not all coals can be utilized equally because they differ vastly in quality. The sulfur content of coals, considered as the most detrimental acid rain-causing element, varies from as low as 0.3 percent in some areas of the western U.S. to 5 percent or more in parts of the Midwest. The chlorine content, which causes corrosion of plant hardware, also varies regionally. The 1990 amendments of the Clean Air Act of 1963 (CAA) require that emissions of sulfur be restricted and rolled back in two stages by the year 2000. There have been a number of reports expressing concern about the future of the industry in the states where high sulfur coal is produced. The remedies devised by the federal government and many coal-producing states in the past to "se-cure" the future of the regional coal industries have focused on the physical task of removing sulfur rather than the economic challenge of doing so at a cost that will enable high-sulfur coals to survive and compete. The past remedies, generally, were not specific enough to account for the characteristics of regional coal deposits and did not look at the coal market as an integrated national and international entity. The State of Illinois has, in recent years, taken a more comprehensive approach to the solution of the problem.

Jan 1, 1992

By R. Venugopal, V. K. Saxena, A. K. Mukherjee

"Coal, iron and manganese ore samples were exposed to different ultrasonic intensities of 250, 300 and 350 W/L for five minutes and to an ultrosonic intensity of 270 W/L for different time durations of 3, 5 and 7 minutes. The ultrasonically treated samples showed reductions in D80 particle diameters of 6 percent for the coal samples, 5.95 percent for the iron ore samples and 35.63 percent for the manganese ore samples during grinding. The ultrasonic treatment was also observed to assist in reducing ash content in the coal product by 8 percent and to reduce manganese losses in rejects by about 5 percent. Ultrasonic treatment was concluded to be capable of assisting in the comminution of friable ores more prominently than the hard and porous materials.IntroductionComminution is an important unit operation in the mineral-processing, cement-making, powergeneration and pharmaceutical industries. But most of the milling technologies are considered to be energy inefficient, with less energy consumed in real size reduction and most of the energy consumed in the machine. This is more critical for the mineralprocessing industry because of the growing need to exploit lower-grade ore bodies and process rejects (Blazy et al., 1994; U.S. Department of Energy, 2005). Low-grade ores require crushing and grinding to liberate the valuable minerals, which are further separated from gangues by various beneficiation methods such as gravity separation, flotation and leaching. Various studies have been carried out to minimize energy consumption during milling by developing pretreatment methods that can initiate new fractures or improve the fracture density in materials before comminution. These studies were mainly focused on chemical additives; thermal, ultrasonic and microwave treatments; and electric disintegration (Klimpel and Austin, 1982; Norgate and Weller, 1994; Bearman, Briggs and Kojovic, 1997; Gaete-Garreton, Vargas-Hermandez and Velasquez-Lambert, 2000; Kumar et al., 2010; Wang, Shi and Manlapig., 2011, Singh et al., 2012).The fragmentation effect of ultrasonic fields in solids has been investigated since the 1950s, and Gärtner was probably the first researcher who attempted it (Gaete-Garreton, Vargas- Hermandez and Velasquez-Lambert, 2000). Sound waves can propagate in solids in the form of longitudinal waves, shear waves and surface waves, and in thin materials as plate waves.In surfaces, fractures and interfaces, various types of elliptical or complex vibrations of the particles make other waves possible. During ultrasonic-vibration treatment, cavitation bubbles nucleate, grow and collapse, generating microjets, whose impacts on the particles initiate microcracks. The ultrasonic waves can enhance the nucleation, growth and coalescence of flaws, caused by tensile or shear stress. The mechanisms operating in the materials and inducing these stresses have been identified as spall and compression-induced tensile microcracks, nucleating at preexisting flaws. These mechanisms are driven by the shock wave and cavitation effects in the surrounding fluid (Chen, Huang and Shih, 2003)"

Jan 1, 2016

By H. P. Hatch

Ash is a material that many people leave to nature to handle. Others sometimes sweep it under the rug to be disposed of by someone else. In our business we cannot do either. In fact the American Electric Power System spends many millions of dollars in plant investment costs to collect the material, and then many more millions to dispose it. In 1965 alone the coal fired steam generating plants in., the AEP System produced approximately 2,400,000 tons of ash, enough to fill 40,000 coal cars which would extend as a single train across the entire states of Ohio and Indiana. Even though our present ash production is large, this is only the beginning when we forecast the future growth of our system. By 1980 it is estimated that our generating capacity will expand to about three times its present size, and with coal as our primary source of fuel our ash production will increase proportionately to about 7 million tons a year.

Jan 1, 1966

By Drew Hobert, John Nielson, Erich Dohm

Metallurgical coal is an essential component for the blast furnace-basic oxygen furnace (BF-BOF) steelmaking process, which accounts for roughly 70% of total global steel production. To meet the growing demand for metallurgical coal, Arch Resources identified the potential to recover low- ash coal from ultra-fines discarded prior to the deslime flotation circuit across their portfolio of operations. Historically, many flotation circuits were designed to discard this ultra-fine coal due to high clay content and technological barriers to cost-effectively upgrade and dewater the coal to a saleable product. Recent advancements in high-intensity flotation technology, including the Eriez StackCell, have enabled coal producers to recover ultra-fine coal while minimizing capital and operating costs. In July 2023, Arch Resources commissioned the first full-scale ultra-fines recovery circuit utilizing StackCell high-intensity flotation technology at the Leer Mining Complex. This paper reviews the approach utilized to develop the flotation process design, learnings from the commissioning and ramp-up period, and performance data through the first year of operation.

Feb 1, 2025

By Thomas F. Martin, Daniel J. Sieve

In April 1988, the joint venture of Morrison-Knudsen and Paschen Contractors (M-K/P) was the successful low bidder for the Metropolitan Water Reclamation District of Greater Chicago's (MWRD) Contract Number 73-164-2H. This project is yet another in the MWRD Tunnel and Reservoir Plan (TARP) devised to control and treat overflows from combined sanitary and stormwater flows. M-K/P's project, located along the Des Plaines River, consists of 21,569' of tunnel mined to a 35' diameter and two tunnels totaling 14,529' mined to a 12' diameter. All three tunnels will have 12" thick reinforced concrete lining. The path for combined sewer/storm waters to reach the tunnels begins at a connection structure, continues through an approach sewer, a sluice gate structure and down a vertical shaft which is topped by a backflow structure. The purpose of the backflow structure is to prevent water surging to the surface as the system fills rapidly. Backflow preventors represent a change in design after problems developed on earlier constructed portions of the T.A.R.P.. On this project, 14 drop shafts channel flows to the tunnel system. In addition to the drop shafts, contract specifications require an emergency or escape shaft be located not more than 4000 feet from the tunnel headings. Due to long reaches without drop shafts, four access shafts had to be constructed. Thus, the total shafts constructed under this contract will be eighteen plus one 30' finished diameter construction shaft located within Miller's Meadows. Figure 1 shows the overall Des Plaines River System and the M-K/P contract connection to previous and future MWRD projects.

Jan 1, 1991

By Richard Giffen, Michael Trabold, Pablo Lemus

"As part of the new 2nd Ave Subway Project, an existing tunnel constructed in the 1970’s will be connected to the new subway and used as new running tunnels. The existing tunnel had to be modified to comply with newer structural and fire life safety codes and to be connected to the new cut and cover station at 96th St. This paper will discuss the complexities of tying an existing tunnel constructed over 40 years ago into the new station and allowing for movements due to the unloading of the existing tunnel and the differential settlement of the two structures during both the construction and permanent condition. Topics that will be discussed include structural analysis, ground improvement techniques, selection of support of excavation walls, working in contaminated soil and instrumentation and monitoring of the structures. It will also cover retrofitting the tunnel to comply with updated Fire/Life/Safety requirements. PROJECT OVERVIEW The Second Avenue Subway (SAS) will be the first major expansion of New York’s subway system in over 50 years. To be constructed in four phases, it will run from 125th St. in Harlem to Hanover Square in the Financial District (see Figure 1). For most of its length, the alignment is directly under the Second Avenue roadway."

Jan 1, 2016

By J. J. Zaluski

The Surface Mining control and Reclamation Act (public Law 95-87) (here-inafter the "Act" or "SMCRA") passed by congress in August of 1977 represents a comprehensive federal scheme for controlling surface coal mining and the surface effects of underground mining through permitting requirements, performance guidelines, and reclamation planning. While the provisions of the Act have been the subject of numerous legal challenges and court battles over the years, it is difficult to identify a more controversial program within the Act than the provisions for designating lands as unsuitable for surface coal mining operations. The lands unsuitable designation process provides for the acceptance and review of petitions submitted by citizens or organizations seeking to have specified land areas designated unsuitable for all or certain types of surface coal mining activities. In filing these petitions, the interested parties or petitioners are required to make allegations about potential adverse impacts on people or the environment and submit evidence supporting their allegations.

Jan 1, 1992

By M. A. Trevits, A. Ozment

"According to the Office of Surface Mining Reclamation and Enforcement, Abandoned Mine Land Inventory System, in 2013 there were 98 underground mine fires in nine states. This is considered to be an underestimate for the actual number of fires nationwide. Many mine fires are started by people burning trash where the coal seam or an abandoned coal mine is close to the surface. Other fire ignition sources include lightning and forest fires. Once ignited, a coal mine fire can easily spread into the remaining coal pillars and mine entries. Once established, the fire creates its own ventilation system supporting further combustion by drawing air down into the workings through unsealed mine shafts, fractures and surface subsidence depressions. As the coal left in the workings from the past mining operations burns, the mine void can collapse, causing subsidence and creating dangerous voids, damaging overlying surface structures and roadways. The products of combustion include smoke and noxious fumes such as carbon monoxide gas. These products are released to the atmosphere through fractures that develop within the ground surface, killing vegetation and creating serious health hazards (Richmond, 2017).Abandoned mine fires, if left uncontrolled, can burn for years and, in fact, one of the most wellknown mine fires in the United States is the mine fire in the Borough of Centralia, PA, that began on May 27, 1962. Reportedly, officials decided to clean up the local landfill for the upcoming Memorial Day holiday by burning the garbage on the site. Unfortunately, the landfill was located on the site of an abandoned strip-pit mine on the edge of the Borough (Dekok, 2009). The strip pit had been left open after being excavated around 1935 and was approximately 23 m (75 ft) wide and 15 m (50 ft) deep. It is believed that the lack of a properly constructed noncombustible shale barrier in the strip pit enabled the fire to spread to adjacent carbonaceous refuse material and then to nearby coal mine workings (PA DEP, 2017). As time went on, the fire grew and spread under the Borough and directly affected the residents despite various efforts to extinguish the fire by the state and federal governments (Fig.1). In 1984, a voluntary program was begun to move residents from their homes. Many accepted buyout offers for their properties and moved elsewhere and after leaving, their homes were demolished. In 1992, the state used eminent domain to take control of all the property within the Borough. In 2013, after years of litigation, the eight remaining residents were allowed to stay for as long as they lived. Today, only a few buildings remain within the Borough (Centralia, PA, 2014). This fire has been burning for more than 55 years."

Jan 5, 2018

By F. B. Brost

In 1976, a decision was made by Anamax Mining Company to install an unusual conveying system to transport ore 10.3 km (6.4 mi) from the new Eisenhower Mine to the Twin Buttes concentrator. The system, supplied by Cable Belt Limited of the United Kingdom, represents a radical departure from conventional belt conveyors. The driving tension is applied through two endless wire ropes driven by a single 2 240 kw (3 000 HP) drive while the belt acts only as the ore carrying medium. Full production was begun in January, 1979. Start-up problems hampered production for several months but were resolved by a joint Anamax-Cable Belt effort. The system has been operating at design capacity for 4-1/2 years, and has proven itself as a reliable, low cost ore transportation system.

Jan 1, 1984

By W. H. Langer

The U.S. Geological Survey (USGS) in cooperation with the New Mexico Bureau of Mines is conducting an assessment of mineral resources in the 36,800 km2 Mimbres Resource Area, southwestern New Mexico. Included in the assessment is a literature-based evaluation of sand and gravel that utilizes third party geologic information. The USGS has developed a method based on existing 1:500,000 scale geologic maps supplemented by remote sensing, statistical models, and point data such as test hole or pit records. The method defines the areal extent, quality, and quantity of aggregate.

Jan 1, 1996

By C. D. Litton, I. E. Perera

This report presents the results of experiments to evaluate different types of mine fire sensors in an underground mine environment using a commercially available atmospheric monitoring system. To determine how well carbon monoxide (CO) and smoke sensors respond for purposes of fire detection, experiments were conducted using test fires of different mine combustibles and for both flaming and nonflaming combustion. The experiments were designed to assess the response of fire sensors to different contaminants and different contaminant levels produced from the test fires. The experiments were performed in the Safety Research Coal Mine at the U.S. National Institute for Occupational Safety and Health’s Bruceton Research Facility in the presence of an average ventilating air velocity of 1.6 m/s (315 fpm). Five fire sensor stations were located downstream of the test fire at fixed locations, with each sensor station consisting of four sensors: a CO fire sensor and three different smoke sensors, of which two were evaluated by the Mine Safety and Health Administration (MSHA) for intrinsic safety and the third was used extensively in underground mines overseas but not evaluated by MSHA for intrinsic safety. All four sensors were mounted near the center of the entry and in the upper onethird of the entry height. A UL-listed combination ionization and photoelectric smoke sensor was mounted near the roof at the first sensor station and its responses were compared against the responses of the four CO and smoke fire sensors. Sensor response data, contaminant travel times, and the impact of fire on the existing ventilation flow are discussed as they apply to earlywarning fire detection. Of significance in the analysis is the need for performance standards for mine fire sensors in order to provide for consistent and timely early warning of developing fires.

Jan 1, 2014