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By Harry Dobroski, Larry G. Stolarczyk

A medium-frequency (MF) communication system has been built and has been tested in underground mines. It provides radio coverage to vehicles and personnel anywhere in the mine via parasitic coupling into existing mine conductors. The system consists of base stations, repeaters, and vehicular and personnel transceivers. Air-core antennas for vehicles and clamp-on antennas for base stations and repeaters were designed for maximum coupling efficiency using existing mine wiring. Personnel transceivers are of a unique vest design that features a low physical profile, good user comfort, and efficient antenna design. In-mine tests show impressive results. Range between rubber-tired vehicles and base stations is often measured in miles. With repeaters, greater range is possible.

By C. H. Elder, Maurice Deul

A 5-hole pattern was drilled from the surface at a site near Oak Grove, Jefferson County, Ala., to degasify the gassy Mary Lee coalbed in advance of mining. Gas and water production was monitored for 1 year, 4 months to allow gas flow to stabilize fully. A thickened water stimulation treatment was designed and applied in one hole of the pattern to evaluate this degasification technique for the Mary Lee coalbed. A gas production rate of 70,000 ft3 /day after stimulation treatment indicates that the use of vertical boreholes coupled with hydraulic fracturing in advance of mining the Mary Lee coalbed would provide for more rapid degasification and could provide a possible source of natural gas.

Jan 1, 1974

By J. J. Forbes

The rapid increase in the quantity of coal being mined by stripping methods is one reason for the increased interest evinced by safety and other agencies in the hazards that are inherent in this Method of mining. The coal-mining laws of some States contain general provisions governing the mining of coal by open-cut methods, but none contains a complete list of specific safety regulations or laws for-the safe operation of such mines. The cool-mining laws of one State empower the head of the coal-mining inspection organization to proscribe regulations for coal-stripping operations and gave him the authority and power to enforce the rules and regulations promulgated by him.

Jan 1, 1944

By Jr. Flynn

"The Bureau of Mines receives and answers many requests for information on the qualities and properties of American coals, and also publishes many papers that deal with coal characteristics. Compilations of chemical analyses of coal from specific locations are contained in a series of technical papers,2/ by States, whereas typical analyses of coal seams, by States and counties, are given in data books, volumes 1 to 7,2/ by producing districts, as defined in the Bituminous Coal Act of 1937. Bulletin 446, ""Typical Analyses of Coals of the United States,"" condenses and supplements these data books, which do not apply to the Western States. Other coal properties are described in numerous publications listed in the Bureau of Mines Bibliography of Publications. However, no recent publication lists average B.t.u. values by rank on a Statewide and national scale. Averages have been estimated in the past, and some of them are included in this paper for comparison.The average and the ranges of as-received B.t.u. values of American coals on a Nation-wide basis, as found by the statistical method described in this paper, are given in table 2 and on a State-wide basis in table 3. The following is abstracted from table 2:In deriving average B.t.u. values for coals, the results depend on the type of data available and the methods of calculation. The data, or analyses, may represent any of three types of samples - mine, tipple, or delivered. In mine sampling, a channel cut is made of a vertical face of the coal bed, carefully excluding most of the impurities, and the material retained is the sample. It is readily seen that mine samples are selected samples and do not strictly represent the unmined coal bed, unless the coal contains no major impurities. Mine samples generally represent the best-quality coal that could be produced. In contrast to mine samples, tipple and delivered samples represent coal that actually has been mined, and their analyses may show either lower or higher values than mine samples of the same coal, depending on treatment and preparation after mining.Of the thousands of analyses accumulated by the Bureau of Mines, most are of either tipple or delivered samples and represent the coal after it has been mined. Any average calculated from this aggregate of data will, consequently, reflect coal that has been produced, and not unmined coal in situ.The method of calculating an average from the basic data also will have considerable influence. If there are three seams of coal in a county, the average analysis for the county is not necessarily the arithmetic mean of analyses of the three individual seams. For a probable average of unmined coal, the B.t.u. values of each seam should be weighted in proportion to the unmined reserves of each seam. In similar manner, an average for past pro¬duction should be weighed according to the past production for each seam. Figures for coal reserves are only estimates based upon geologic evidence and its interpretation. Production records are much more accurate than estimated reserves, although detailed production records for individual seams by counties are very few."

Dec 1, 1949

By Joseph A. DeCarlo

This information circular presents data for 1960 on individual coke plants in the United States. All oven-coke plants in existence, whether active or idle at the close of the year, are listed in this report. With two exceptions, only beehive plants on which reports were submitted to the Bureau of Mines are included. Although the Bureau was unable to obtain reports from these two active plants in 1960, the number of ovens and annual coke capacity are estimates, based on previous reports filed with the Bureau of Mines. Accordingly, there were 73 oven-coke plants in existence at the end of 1960 of which 70 were active. Reports were received on 44 beehive plants of which only 13 were in operation at year end. Oven-coke plants are listed alphabetically by States in table 1 which shows the name and address of the company, location of plant, classification or type of ownership, number and type of ovens, annual coke capacity, and coal-chemical materials produced. The terms "furnace" and "merchant" plants used in this and all other reports of the Bureau of Mines designate the type of ownership. Furnace plants are those owned by iron and steel companies whose main business is production of coke for use in their own blast furnaces. Merchant plants are those associated with chemical companies, gas utilities, as well as those that produce for sale on the open market metallurgical, industrial, and residential-heating grades of coke and coal-chemical materials. The annual coke capacity shown for each plant in this table is based on the minimum coking time necessary to produce coke with qualities suitable for its intended use. Therefore, the annual capacity of a plant may change from year to year, depending on age and condition of ovens, the character and quality of coal carbonized, the grade of coke required, and other factors. For example, annual coke capacity of a coke plant primarily making foundry coke with longer coking cycles would be lower than one making blast-furnace coke. Also some ovens must be operated at slightly lower than normal flue temperature because of the condition of the refractories and maximum capacity would be somewhat lower than designed capacity. For this reason, the capacity reported to the Bureau of Mines may differ from the designed or rated capacity estimated by the coke-oven builders at the time of construction. For example, if the generally accepted standard coking rate of one inch per hour were used on all ovens to calculate total annual capacity, it would have been 80.4 million tons or 2 percent higher than the capacity reported to the Bureau. Because of the factors mentioned above, the annual coke capacity shown in this table is believed to be a reliable measure of the practical operating capacity of the industry.

Jan 1, 1961

By Bob Thomas, Syd Peng, Quanzhong Gu, Gene Wilson, Gerald L. Finfinger

Identifying the properties of overlying rocks in underground mining operations is important to ensure the appropriate roof support design is used to maintain stability of the mine entries. Recently J. H. Fletcher & Co. developed a monitoring and control system for roof bolters for the underground mining industry. The system records the drilling parameters used during roof bolt drilling and the information can provide insight into the physical properties of the roof strata. The parameters include thrust, rotational speed, torque and velocity and the measurements are collected every 0.1 second during the operation. The drilling parameters were analyzed to determine the application of identifying the strength of rocks being drilled from the measurements. The data was converted into the specific energy of drilling which is a measure of the amount of energy required for removing a given unit of rock during a drilling operation. The laboratory studies completed to date indicate a fairly high correlation between the specific energy of drilling and the unconfined compressive strength of :he rocks that were drilled. Additionally, the drilling parameters were shown to be effective for identifying the presence of fractures or bed separations between rock layers. The thrust, torque and specific energy of drilling were all good indicators for identifying the fractures or separations. Regardless of the drilling parameters used during the drilling experiments, the location of the fractures were identified. In order to determine the application of the drilling parameters for identifying roof rock properties, two series of experiments were conducted. The first series of experiments used three "manufactured" roof layers that had various rock samples embedded in concrete blocks. The rock samples included three types of sandstone, marble, and argillite. Another concrete block was poured with foam inserts to simulate large bedding separations (2 to 8-in). Two other manufactured blocks were constructed using high-strength concrete with cardboard layers embedded to simulate smaller fractures or bedding separations. The size of the cardboard layers varied from 1/8- to 1-in thick. One of the blocks had the cardboard layers embedded at an inclined angle to determine the effect of the orientation on the drilling parameters. A series of experiments was conducted with the rotational speed and the penetration rate held constant and the thrust and torque allowed to vary. The information collected from the experiments is used to determine the application of the drilling parameter measurements for identifying rock properties, fractures and bedding separations.

This chapter presents data on occupational exposures from several sources. Data from compliance samples obtained by MSHA inspectors are presented in table 6-1 for coal mine dust and silica dust, and in tables 6-2 through 6-6 for metal fumes. Since these samples were taken for compliance monitoring rather than as part of a survey of the industry, it is difficult to predict how well they indicate actual exposures for all mining operations. In the coal industry, 7.8% of all respirable dust samples during 1986-1995 were above the permissible exposure limit (PEL). Of silica dust samples obtained during the 10-year period, 23.7% were above the PEL in coal, 16% in metal, 10.8% in nonmetal, 9.1% in stone, and 7.6% in sand and gravel. Of metal fume samples, silver samples showed the largest percentage above the PEL-approximately 48% of samples in both metal and nonmetal. Tables 6-7 and 6-8 present data on noise exposures from the MSHA "dual threshold" survey, which was published in the Federal Register [61 Fed. Reg. 66347 (1996)] as part of a proposed rule change for occupational noise exposure in mining. This study examined a group of samples obtained during 1991-1995 and compared the percent of samples that were above two separate specified limits. The first limit was the current noise standard, a time-weighted average of 90 dBA, calculated to include only exposures at 90 dBA and above. The second limit was a time-weighted average of 85 dBA, calculated to include exposures at 80 dBA and above. Tables 6-8 and 6-9 refer to musculoskeletal overload conditions examined in the National Occupational Health Survey of Mining (NOHSM) [NIOSH 1996]. Table 6-8 shows the operational definitions for each condition; table 6-9 shows the percentage of the workforce potentially exposed, by commodity. Across all commodities, a large proportion of workers were exposed to musculoskeletal overloads due to positioning of the neck and back; positioning and motion of the forearms, arms, and shoulders; heavy lifting; and positioning and movement of the lower limbs. The recorded overloads were defined in the survey and did not exceed any NIOSH, MSHA, or OSHA guidelines for musculoskeletal overloads. Further information on this survey appears in appendix A.

Jan 5, 2000

By G. L. Oldright, Virgil Miller

"ACKN0WLEDGMENTSThe data given in this paper were collected at the Bunker Hill smelter through the courtesy of Stanley A. Easton, the vice-president and general manager, Frank M. Smith, the smelter director, and with the assistance and cooperation of A. F. Beasley, the smelter superintendent, and his staff members.THE BLAST FURNACE AND PLANTThe general lay-out of the recently built (1917) Bunker Hill plant has been given in the technical press in articles that were cited in Report of Investigations 3088. In addition it may be noted that the description of an ideal smelter given by Riddell 5 a year later fits the Bunker Hill smelter very well, with some changes, such as the location of the stack, made necessary by topography. For purposes of this article on the blast furnace it may suffice to state that the plant is one of the ""side hill location"" type. The various successively lower benches may roughly be considered as made for (1) the stack, (2) Cottrells and bag houses, (3) Dwight and Lloyd sintering machines with the equipment or bins for handling or mixing the feed and storing the finished product, sinter, and (4) the blast furnace feed floor with a slightly rising gradient to the bottom of the bins for sinter, feed, and take. The lowest bench (5) might be considered that of the blast furnace tapping floor at which or at appropriately slightly lower elevations are located the units for softening, refining, and treating precious metals, and for casting and loading lead. A very careful study of grades was made in order to be able to handle the products easily. All units were left with at least one end open to permit expansion of the plant, it desired, and each unit was separated from the other, evidently so that the operators on one level would be annoyed as little as posssible with the products made on another."

Apr 1, 1931

By Dorsey A. Lyon, Robert M. Keeney

This bulletin is one of a series dealing with the application of the electric furnace to the smelting of ores and the manufacture of alloys, and is published by the Bureau of Mines in the endeavor to increase efficiency in metallurgical processes. The bulletin presents, first, a critical discussion of the possibility of smelting copper ores in the electric furnace; second, the results of the experimental work of other investigators on the electric smelting of copper; third, the results of experiments by the authors on the electric smelting of native copper concentrates and sulphide copper ores; and, fourth, a comparison of the electric furnace with the blast furnace and reverberatory furnace for copper smelting. Before considering the electric smelting of copper ores the reader should understand that the electric furnace was not developed as a competitor of the combustion furnace, but for the purpose of doing high-temperature work that can not be done in the combustion furnace, and for the treatment of ores from deposits that are in regions where fuel is scarce and costly but hydroelectric power is comparatively cheap, as in Chile, and in certain parts of Canada, the United States, and Mexico. Furthermore, it is not the object of this report to try to prove that the electric furnace should replace the reverberatory or the blast furnace, as used at present in smelting copper ores, but to show that the electric furnace may be used with advantage in localities where conditions are not favorable to the use of the reverberatory or the blast furnace. For example, otherwise valuable ore deposits may be situated in a district so remote from, or inaccessible by, railway that the cost of get- ting coke for smelting, or of transporting the ore to a smelter, is pro- hibitive. If there is sufficient water power at hand, from which electric power can be developed at a reasonable cost, and this electric power is used for smelting the ore in an electric furnace, with subse- quent bessemerizing, if necessary, the concentrated product may be

Jan 1, 1915

By Richard Mainiero, James H. Rowland

For many years there have been small scale tests available for evaluating the toxic fumes production by cap-sensitive explosives (DOT Class 1.1), but these could not be used with blasting agents due to the large charge sizes and heavy confinement required for proper detonation. Considering the extensive use of blasting agent in construction and mining, there is a need to determine the quantities of toxic fumes generated by blasting agents. At the International Society of Explosive Engineers Twenty Third Annual Conference on Explosives and Blasting Technique in 1997, the authors reported on a facility for detonating large (4.54 kg), confined blasting agent charges in a controlled volume that had been constructed at the National Institute for Occupational Safety and Health’s Pittsburgh Research Lab’s Experimental Mine. Since 1997, this facility has been used to collect data on toxic fumes produced by the detonation of various ammonium nitrate/fuel oil (ANFO) mixtures and several cap-sensitive explosives. ANFO composition ranging from 1 to 10 percent (pct) fuel oil have been studied. As expected from previous studies, with an increase in fuel oil content the carbon monoxide production increases, while nitric oxide and nitrogen dioxide production decrease. The detonation velocity varies from 3,000 to 4,000 m/sec for the 1to 10 pct range of fuel oil content, suggesting that ANFO mixes with improper fuel oil content may appear to detonate properly, while their fume production differs significantly from optimum. The study also considers such factors as degree of confinement, water contamination, and aluminum content on blasting agent fume production. Results indicate that water contamination of the ANFO has little effect on carbon monoxide production, but causes significant increase in nitric oxide and nitrogen dioxide production. Decreasing confinement from Schedule 80 steel pipe to 0.4-mm thick sheet metal also has little effect on carbon monoxide production, but significantly increases nitric oxide and nitrogen dioxide production. Adding5 and 10 pct aluminum to the ANFO had no clear effect on carbon monoxide, nitric oxide, or nitrogen dioxide production.

By David L. Moffatt

Considerable current interest is evident[l,2] in the use of transient electromagnetic methods for subsurface remote sensing. A transient method is discussed which uses a periodic video-type pulse containing a wide frequency range. A video pulse is used as an interrogating signal both for "target" identification and detection for relatively short depth (c 20 meters) applications in soil and soft rock media. If the medium is favorable, e.g., hard rock, greater depth applications appear to be feasible. The same procedures would be applicable for deep geological exploration but would require a substantial reduction in frequency and increase in target size. It should be noted that video pulse generators with 35 kv peak voltage and nanoseconds base widths are now within the state-of-the-art, thus significant power over broad spectral ranges is possible. In the design of a video pulse sounding system, 5 main problem areas can be identified; 1 ) selection of the pulse shape or spectral content of the video pulse, 2) design of a radiating structure which effectively couples such a pulse into the medium, 3) isolation of the radiating and receiving mechanisms, 4) realistically accounting for the dispersion and attentuation of the medium and the air-medium interface, and 5) interpretation or processing of the received signal waveform. Each of these problem areas will be discussed and illustrated with experimental and/or theoretical results. The Video Pulse Selection of the proper video pulse signal is dictated by 3 considerations, the maximum desired depth of penetration, the attenuation of the medium and the required resolution and size of the target. For a lossy medium, penetration and resolution are clearly at cross purposes and a compromise is necessary. The exact nature of the compromise is dictated by the application, but the spectrum of the video pulse should not contain any frequencies higher than the predicted cut-off, i.e., that frequency which is attenuated to the threshold level of the receiver. As a practical matter, it may be necessary to select 1 or 2 video pulses reasonably suited

Jan 1, 1973

By K. L. Rubow

"Diesel exhaust and mineral dust concentrations have been measured for aerosols generated in the laboratory and as found in five underground coal mines- 3 utiliting diesel-powered hallage equipment and two electric-powered equipment. Two source apportionment techniques have been applied to differentiate between the mineral dust and diesel exhaust aerosol concentrations. The first technique, using a microbrifke uniform deposit impactor CMOUDI) for size selective sampling, is based on modeling aerosol size and the premise that the diesel exhaust portion of .the aerosol is predom1nately submicrometer and the mineral dust portion is mostly greater that one micrometer in size. The second technique, Chemical Mass Balance CCMB) modeling, was used to referee the analysis of diesel exhaust and mineral dust aerosol concentrations from the size selective sampling results. ,The MOUDI size distribution data were modeled to obtain parameters describing the fine and course fractions of the sampled aerosol and to estimate the contributions to each mode from both mineral ·dust and diesel exhaust aerosol sources. The results showed the size distribution of the mixed aerosols exhibited two definite modes with the minimum between the modes occurring at 0.8 um. For the diesel equipped mines, this analysts yielded an average value for the fraction of the fine aerosol attributable to mineral dust of 1 pct. Less than 5 pct of the coal mine diesel aerosol was found in the coarse size fraction. CMB analysis confirms the original premise for using aerosol size to separate diesel exhaust and mineral dust aerosol during sampling."

Jan 1, 1988

By C. B. Manula, R. L. Sanford, R. A. Rivell

A central requirement for using simulation models is the need for retrospect testing to validate experimental conclusions. Acceptance of a model by managers and safety practitioners is more likely to depend on its tested performance in-the field rather than on the underlying logic or the validity aspects of the model itself. It is here that simulation bridges the gap between theory and useful design procedures. The original version of the rail haulage sub-assembly was success¬fully tested in the field (Sanford, 1969). However, the case studies that were described here involved single-stage haulage and restricted jobtypes from UGMHS. Since this report together with Volume VI (Production Subsystem) describes extensive changes and modifications to the rail haulage sub-assembly and UGMHS, field tests were necessary to verify both the rail model and the linking concepts to the Produc¬tion Sub-system. Mine Description The candidate mine selected for model verification works the 6 1/2 foot Pittsburgh seam. Shaft openings are used for manways and ventilation and a dual compartment slope for materials handling. In the bottom half of the slope, a hoist with track handles supplies and equipment. In the upper half, a 42 inch belt conveyor travelling at 450 fpm moves coal from a rotary dump to the surface. The immediate roof is shale with the first 12 inches taken during development mining. About 4500 raw tons are produced daily from seven face units and one spare working three shifts. At seven of the sections,

Jan 1, 1974

By Hon-Chung Ko

This Bureau of Mines report provides the enthalpies of formation of cupric bromide and cuprous bromide as determined by hydrochloric and hydro-bromic acid solution calorimetry. At 298.15 K, the values are -33.10 ± 0.4 kcal/mole for CuBr2, and -25.24 ± 0.25 kcal/mole for CuBr.

Jan 1, 1975

By N. F. LeJeune

For a number of years the Bureau of mines has conducted semi-annual surveys to determine the changes in the characteristics of the motor gasoline being sold in the United States. The Bureau of Mines surveys, from April, 1917, to January, 1943, indicated a progressive decrease in the end point range. The survey for July, 1923 showed an interruption in this progressive decrease. This interruption, as shown in Table 1, in the line marked "Difference," was apparently a definite one, for the data obtained in the surveys of July, 19233, January, 19244, and the present one, apparently substantiate it. The figures in Table 1 were obtained by averaging the end points of the least volatile and most volatile samples of gasoline. For example, of 850 samples analyzed in 1919, the 10 per cent (85 samples) having the highest end points and the 10 per cent having the lowest end points were grouped, and the end points of each group averaged. These averages are represented in the table as the "Maximum 10 per cent" and the ?Maximum 10 per cent," respectively. The same scheme was used on the succeeding surveys.

Jan 1, 1924

By Jr. Herty

Ferromanganese continues to be an indispensable requirement in steel manufacture. Approximately 470,000 of the 80 per cent ferro-alloy was consumed in 1929 and increasing amounts will be required annually by the steel industry unless some satisfactory substitute is found. An average of 14 pounds of metallic manganese is used for each ton of steel produced, The principal use of manganese is for de-oxidation of the metal in the steel refining processes, although a considerable amount is also used for the production of special manganese steels. Unfortunately, domestic production of manganese ore is inadequate to meet normal peace-time requirements, not to mention increased abnormal war-time demands. The rather large quantities of low-grade manganiferous iron ores which occur in the Coruna Range in Minnesota have for a number of years greatly appealed to those interested in the development of a domestic source of the supply. The North Central Experiment station of the Bureau of Mines has made an elaborate study of the possibilities of the pyrometallurgical treatment of ores from these deposits and much of the valuable information secured by them has already been published.

Jan 1, 1930

By G. B. Shea

The accident experience of the California petroleum industry for 1927 was characterized by a decrease it .the number of fatalities. The year closed with a total of 41 fatal accidents, as compared with a total of 54 for the preceding year. 3 In percentage, the figure for 1927 represents a decrease of 24 per cent from that of 1926 and evidences the promising results of organized safety work, in which the industry in California has taken an absorbing interest. The percentage of decrease for 1927 is the largest recorded in any one year since the compilation of the fatality record in the California petroleum industry was begun. Although good progress has been made during the past few years, much remains to be done to reduce still further the human and economic waste caused by accidents. This review is intended to show the employee, as well as the employer, the proximate and contributing cause of accidents. To increase the value of the report, preventive measures in various instances are suggested, on the theory that accidents of a similar nature will occur unless remedial action in taken to remove the cause.

Jan 1, 1928

By Robert P. Vinson, Fred N. Kissell, Edward D. Thimons

Because of the high number of accidental methane gas ignitions in metal and nonmetal mines, the Bureau of Mines searched for a simple guideline that would allow mine personnel to evaluate the methane hazard in a given mine. Air samples were collected by the Bureau in 53 metal and nonmetal mines and analyzed for trace evidence of methane gas. Samples were collected in the returns and at the working faces. Those mines classified as gassy by the Mine Safety and Health Administration had a significantly higher average methane concentration than those classified as nongassy. Of the 9 gassy mines sampled, 7 had methane concentrations above 100 ppm, whereas only 1 of the 44 nongassy mines had a concentration above 100 ppm. The 100-ppm concentration may be used as a simple and convenient guideline for forecasting the methane hazard in a mine, whether or not the mine is classified as gassy. There was no consistent correlation between commodity mined and methane concentration, nor was there a correlation between mine depth and methane concentration. Neither of these factors can be considered a guideline for predicting methane hazards.

Jan 1, 1979

By Connie S. Musulin

The Bureau of Mines conducted an experiment at Exxon Mineral Co.'s Buffalo Shaft Operation to determine the time required for radon concentrations to return to a base average after fan shutdowns. Shutdown times ranging from 5 min to 16 hr were evaluated. An equation was derived to calculate a ratio that determines the time required for the radon concentration to return to the average level that existed in the mine prior to shutdown. For fan shutdowns of 15 min or more, underground personnel should be evacuated to areas with natural downcast ventilation. For shutdowns of less than 1 hr, personnel should not return to the working area until the elapsed time is four times the shutdown, or until the working area is resampled and found safe. If the mine is not in production during weekends, the downcast fans can be turned off .from midnight Friday until 4 p.m. Sunday, and the radon daughter concentration should be below 1 WL throughout the mine by the start of the shift Monday. This fan shutdown would conserve energy and save the mining company an estimated $21,000 each year.

Jan 1, 1982

By Jürgen F. PH. D. Brune, Alex C. Smith, Michael A. Trevits

Underground coal mine fires in the United States continue to present a significant hazard to the safety and health of mine workers. The leading causes of mine fires include flame cutting and welding operations, frictional heating and ignitions, electrical shorts, mobile equipment malfunctions, and spontaneous combustion The National Institute for Occupational Safety and Health (NIOSH) is conducting an in-depth program of research to address mine fire prevention, early and reliable fire detection and mine fire suppression and control technologies. One segment of the research portfolio is focused on remote methods for addressing coal mine fires. This research is important because remote methods represent the primary means of fighting a mine fire when conditions are too dangerous to fight the fire directly underground. Technologies under investigation include remote methods for installing ventilation control devices (mine fire seals) and remote methods for suppressing the fire using, the injection of inert gas, gas-enhanced foam and jet engine exhaust gases into the fire zone. This paper presents a summary of remote mine firefighting technologies used in the U.S. and the results of completed NIOSH research.