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By Eugene Baker, Joseph Cervik, Albert Sainato

In Europe, water infusion is used widely to reduce generation of respirable dust during mining. Its use in the United States is limited to a few plow operations in the Pocahontas No. 3 Coalbed. This Bureau of Mines report describes the technology for infusing water in to a longwall panel and reports the results of a recent demonstration in the Lower Sunnyside Coalbed that achieved dust reductions averaging 58 pct. Because water infusion increases moisture content of the coalbed, face air velocities in excess of 500 ft/min (2.5 m/s) are possible, further diluting dust levels before dust entrainment occurs. An economic analysis shows a 23-pct reduction in operating costs when coal production is increased by changing from unidirectional mining to bidirectional mining with water infusion.

Jan 1, 1983

By A. L. Murray

"Welfare endeavor in connection with both the metal and the coal mines of Utah has shown gratifying progress during recent years, and in most mining towns of the state, both the operators and their employees deserve much credit for the efforts put forth to better the living, working, educational and recreational conditions. Progress has been and is being made, but there are still a few important towns where purer water and better sewage disposal are pressing needs.In the older metal-mining towns that are incorporated and are independent of the mining properties operating in the vicinity, less opportunity is presented for the companies to exercise efforts looking toward improved welfare conditions than in company towns controlled by the mine operators.However, even in such towns the companies can do much to better welfare conditions, as shown by the progress in Bingham Canyon during the past several years. The Utah Copper Company has spent $800,000 since 1920, in the erection of modern brick cottages, apartment houses and the Germnell Memorial Club. The cottages and apartment houses have every convenience to be found in up-to-date city homes. The Gemmell Memorial Club erected and equipped at a cost of $175,000 was provided by the company for the benefit of the Utah Copper employees living in the canyon and has been made the recreational center for the camp. Another improvement is the $100,000 fireproof hotel built by the United States Mine of the United States Mining, Smelting and Refining; Co. in the Copperfield section of Bingham Canyon. This hotel will accommodate 105 men exclusive of hotel help and has all the conveniences of a city hotel."

Sep 1, 1925

By G. W. Groove, E. E. Quenon

"INTRODUCTION Uncontrolled mine fires originating in exposed coal beds through the acts of careless or irresponsible persons present a serious threat to buildings, surface property, and the life and health of persons near the affected area. Apparently, the seriousness of such fires is not fully understood by property owners or those residing in the vicinity, as practically nothing has been done to alleviate conditions. In many instances, such fires have been active for several years before property owners or civic organizations have shown any interest toward having the fire extinguished. Recommendations by Bureau of Mines investigators in the interest of controlling such fires are seldom followed, as the Bureau cannot provide the funds for doing the work.Several uncontrolled and widespread fires are burning along the outcrop of coal beds and in underground abandoned mine workings within a 25-mile radius of Pittsburgh, Allegheny County, Pa. If these fires are permitted to continue to burn unabated, the ultimate results may be far-reaching. Most of the outcrop fires investigated are believed to have originated from burning rubbish, forest fires, or workmen, hunters, or others building fires near the outcrop of ,the coal beds. In other instances, smoke and fumes have suddenly appeared in the vicinity of abandoned coal-mine openings, indicating that a fire has either burned its way along the outcrop of the coal bed or has traveled through the abandoned mine from another location. An underground or outcrop coal-mine fire will be very likely to continue to burn as long as an oxygen supply is present.; and, so far as is known, such fires do not stop burning automatically until virtually all combustible matter is consumed."

Feb 1, 1948

By Joseph Cervik, Maurice Deul, Albert Sainato

This Bureau of Mines report deals with water infusion of coalbeds, which can control methane emission at face areas during developmental mining and which may sometimes suppress dust. Studies show that water infused into the coalbed flows through the fracture system and displaces the methane in the fractures and prevents migration from the solid coal. Displaced gas migrates away from the face area that has been water infused and enters the return ventilation airways. A gradual decrease in methane emission is observed from the start of infusion until the infused zone is mined through. Depending on the permeability of the coalbed, infusion pressures ranged from 300 to 2,200 lb/in2. Face emissions in the Upper Kittanning coalbed were reduced by 89 pct; reductions of 38 to 79 pct were measured in the Pittsburgh coalbed depending on the relationship between the face cleat direction and mining direction. Respirable dust levels were reduced by about 75 pct on a longwall section in the Pocahontas No. 3 coalbed and by about 50 pct on a development section in the Upper Kittanning coalbed, but no statistically reliable reduction was found in the respirable dust levels in the Pittsburgh coalbed.

Jan 1, 1977

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 Walter J. Frank

Thls report summarizes work done under Bureau of Mines contract H0357100, "Development of a Crimp Connector for Trailing Cable Splices." The purpose of this effort was to establish optimum connector design conditions to meet flex cycle, pullout and electrical resistance criteria on phase power conductors. Field testing of "optimum design" connectors is briefly discussed. One of the primary objectives of contract H0357100 was to enable one to design better performing phase conductor connectors. Illustrating the practical significance of this 1s a discussion on the development of a new splice kit for trailing cables. The connectors in this kit were designed in accordance with the design methods described in the contract final report. Kit components, test data, and a connector installation tool are also discussed. The successful effort on the phase connector has resulted in contract H0377042, entitled "Design and Testing of Joining Sleeves for Trailing Cable Ground and Pilot Wires." The purpose of this contract (currently in effect) is to improve ground-conductor and pilot-wire performance. Significant findings to date are discussed.

Jan 1, 1979

By D. E. Ingersoll

This report describes the preparation characteristics of anthracite from the Mammoth and Holmes veins in Schuylkill County, Pa., as determined by the Federal Bureau of Mines laboratory separations at specific gravities of 1.50 to 1.90. The Holmes vein anthracite contains approximately 13 percent ash, and the Mammoth vein contains about 9 percent as fed to the breaker. Crushing Broken, Egg, and Stove sizes from each vein produces Pea-size anthracite of lower ash content than that contained in Buckwheat No.1 size and smaller. The Buck-wheat No.5 size has the highest ash content of all the sizes examined. Potential recovery from a mixture of the two veins as received at the breaker, separated at 1.90 specific gravity, is approximately 64 percent of the feed at 11.0 percent ash. The same materials separated at 1.80 specific gravity yield about 61 percent with an ash content of 10.1 percent. All rejects are from the Holmes vein, because the entire Mammoth material is less than 10.0 percent ash.

Jan 1, 1960

By Jeffrey M. Listak, Gregory J. Chekan

The U. S. Bureau of Mines is investigating longwall panel layouts to maximize coal recovery and minimize interactive problems in multiple-seam operations. When coalbeds are longwall mined in descending order, the transfer of stress from overlying gate roads is a major design constraint affecting pillar stability in the lower mine. The lower mine gate road pillars must be properly designed to withstand the additional load transfer if gate roads are superpositioned in successive seams. The Bureau's MULSIM/NL model, a boundary element computer program, was used to analyze load transfer mechanics for superpositioned gate road pillars. Analysis of Longwall Pillar Stability (ALPS), an empirically based design method for longwall gate road pillars, was used to calibrate model input parameters. ALPS provided a basis to verify model trends and to recommend limits for safe pillar design when superpositioning longwall gate roads. The attributes of the MULSIM/NL model and ALPS were combined to develop a modified method for estimating pillar stress for multiple-seam cases. The modified method uses a multiple-seam factor (MS) to estimate the stress on superpositioned lower mine gate road pillars. Numerical analysis shows that MS depends on the interburden thickness and pillar width.

Jan 1, 1992

Accurately measure time of detonation and explosive detonation velocity in a blasthole for analysis of explosive performance and delay intervals. Approach A blasthole-monitoring fiber optic probe was developed consisting of filer optic cable to carry the fight and a sensor to detect and convert the light signals into electrical signals. Events can then be recorded on an oscilloscope, tape recorder, digital computer, or start-and-stop timer. This method is simpler to use and more immune to electronic noise than existing resistance techniques. The fiber optic material,, are inexpensive and easy to obtain, and the recording devices, such as storage oscilloscopes, arc available or easy to obtain. The probe provides the mining industry, explosive manufacturers, and those studying blasting, with a practical alternative to complex and expensive coaxial cable reflectometry, resistor strings, or resistance wire methods for determining explosive and detonator performance. How It Works The fiber optic cable is a plastic light guide consisting of sixteen 0.01-inch-diameter optic strands having an overall outside diameter of 0.087 inch. The receiver module incorporates a photodiode to detect the signal and an integrated circuit receiver for signal amplification into one package about 1/2 by 5/8 by 7/8 inch.

Jan 1, 1989

By D. G. RUNNER

Information Circular 6148R, " Selected Bibliography of Minerals and Their Identification ," was issued in June 1929 , revised in July 1937, and again in October 1938. The popularity of this circular , combined with the desire to make it more comprehensive , has occasioned the preparation of this compilation of references . Where possible , date of publication , publisher, current price , and number of pages are given, although prices are subject to change at intervals . The references are grouped under the following headings : minerals , gems , rocks , geology, geomorphology, engineering geology , prospecting, mining . engineering, microscopy, technical dictionaries , and miscellaneous . For ready reference, the authors ' names are arranged alphabetically under each grouping . This list is not comprehensive, but contains only those references in most common use and which are generally available in public college libraries .

Sep 1, 1949

By Joseph P. Flick, Kathleen M. Kowalski, Lynn L. Rethi, Roberta A. Calhoun

Many miners are involved in tasks at the mine site that are similar to those sub-tasks performed in general construction, maintenance and repair (CMR) type work activities. As a result, many of the injuries in the mining industry today can be traced to employees performing these CMR type work activities. Indeed, a recent analysis of a major aggregate company revealed that 65% of all injuries documented originated from performing such CMR activities. It is hypothesized that the number of injuries to miners performing construction, maintenance and repair (CMR) work activities on mine property may be reduced through improved training that focuses on better hazard recognition using the numerous visual and other cues that are available for evaluating workplace health and safety hazards. To this end, researchers at NIOSH’s Pittsburgh Research Laboratory have merged two proven methods of training miners to recognize hazards, stereoscopic (3-D) slides and the concept of degraded images, into this training program. Stereoscopic (3-D) slides have been shown in earlier NIOSH and U.S. Bureau of Mines research to be an effective training aid for improving the ability of miners to recognize various geologic and mining-induced irregularities that can cause groundfalls.3 They realistically portray the natural mine environment, and thus are an excellent training aid for teaching miners to recognize such visual cues. The degraded image concept, originally developed by the military and used for target detection training, describes scenes where the target is partially hidden by cloud cover, dust, rain, natural barriers, buildings, or other obstructions that can camouflage or confuse the target. Research had shown that flight observers who were trained with less than ideal (or degraded) pictures were more successful in subsequent identification of targets than those trained using ideal (or highlighted) pictures of targets. In order to investigate this concept for training miners to recognize hazards, NIOSH researchers developed a prototype hazard recognition training program using such mining scenes. A control program based on traditional highlighted mining scenes was also developed. Both programs were applied to subjects in a field experiment. Results indicated that miners trained with the degraded images did significantly better on a follow-up test of hazard recognition.4 This hazard recognition program teaches trainees to look for hazards in a more realistic manner than that of the control program. This specific training program for CMR activities involves using the degraded image concept and 3-D slides. The module is designed to educate workers on hazard identification techniques and safe work practices. It focuses on teaching miners techniques for recognizing visual (sight) cues, and then uses these cues to evaluate mining conditions. It should be stressed that other senses, such as sound can also play an important role in hazard detection.

Jan 1, 1999

The object of this program was to extend the capabilities of visual paging systems both in size and function. The system developed uses the mine pager phone line for communication, monitoring, and remote control. A central station, using a mini-computer, transmits signals by phase inversion modulation of a 16,384 Hz carrier to as many as 999 remote units. The remote unit addressed returns an echo to indicate that it is functioning and, in the case of monitor units, to convey the monitor data. Magnetically latched display discs, which can be seen from both sides when posted, are used for visual paging. Lists of the addresses of posted pages, unanswered pages, and non-echoing units are prepared by the central station computer. The system was designed to be intrinsically safe and should operate for three months on a 12-volt lantern battery.

Jan 10, 1980

By M. M. Tilman

The Bureau of Mines conducted research to determine whether it is possible to substantially improve the fatigue resistance of lead sheet by means of surface coatings. Five types of coatings were applied to unalloyed chemical lead sheet. Flexural tests revealed that the best fatigue resistance was obtained with coatings of vacuum grease. Vacuum-grease coatings on unalloyed lead sheet resulted in fatigue resistance at least as good as that of the fatigue-resistant alloy Pb-0.04 Ca. Coated lead sheet was also tested in short-time tensile tests and in tensile creep tests. Tensile and yield strengths were increased by several of the coatings with only moderate loss of ductility. Creep resistance was also improved in varying degrees by most of the coatings. The Bureau also conducted research on the effectiveness of noise barriers by using sheet lead in combination with other materials. Noise barriers consisting of continuous-cast sheet lead with gypsum board were found to be effective and relatively inexpensive barriers.

Jan 1, 1978

By David F. Gearhart, Thomas M. Barczak

This U.S. Bureau of Mines report examines the roof and floor contact pressure provided by the interaction of a shield with the surrounding strata. Controlled forces were applied to an 800-ton two-leg shield in the Bureau's mine roof simulator; the distribution of forces acting on the canopy and base of the shield were measured with 24 hydraulic pressure cells. Several influential factors that affect the load distribution were investigated: (1) the magnitude of loading (leg pressure); (2) the profile of the canopy, principally the upward-sloping tip; (3) the base-lifting device; (4) horizontal load acting on the shield; and (9 compliancy of the immediate roof and floor. It was concluded that the shield does not develop full canopy or base contact without deformation of the strata. Maximum contact pressures are developed at the rear of the canopy and on the toes of the base. Less than 10 pct of the available shield capacity is developed at the canopy tip despite the design intention to ensure tip contact. Horizontal loading reduced the toe pressure acting on the base by as much as 75 pct. The base-lifting device exaggerated the inherently high toe loading, increasing the contact pressure by more than 200 pct.

Jan 1, 1992

By Kathleen M. Kowalski-Trakofler

This paper discusses human judgment and decision making under stress. The authors review selected recent literature across various disciplines and suggest a definition of stress within the context of decision making during the management of emergencies. They also discuss fieldwork by the Pittsburgh Research Laboratory, NIOSH, which explores traumatic incident stress, the relationship between previous training and performance under stressful conditions, and human behaviour in underground mine fires. The authors assert that stress is one of the factors that decision makers must contend with in most life-or-death situations. They suggest that a better understanding of individual judgment and decision making activities whilst under stress would yield a better understanding of how people reach the choices they make in emergencies. This enhanced understanding would be of enormous value to emergency managers, researchers and policymakers.

Jan 1, 2003

By Oleg Terichow

Electrophoretic mobility measurements were made by the Bureau of Mines on samples of a Florida phosphate slime to determine the optimum conditions of coagulation and settling in an aluminum sulfate solution. Addition of anthracite to promote mutual coagulation demonstrated the practicability of heterocoagulation by reduction of the repulsive effect of double layers. By proper selection of the electrolyte and its concentration, the reduction of the double layers to a net zero point of charge causes the predominance of Van der Waals' forces of attraction leading to the coagulation and rapid settling of both particle systems, as is predicted by the Derjaguin-Landau-Verwey-Overbeek theory of colloidal stability. Confirmation was found in the microfiltration tests where a modified Carman equation was applied to evaluate the specific filter bed resistance.

Jan 1, 1975

By W. W. Adams

luring the past two years the Bureau of ?,lines has been receiving from 100 to 150 coal mines in various States a report of each accident causing death, permanent total disability, permanent partial disability, or temporary disability lasting beyond the remainder of the day or shift on which the accident occurred. For each 100 accidents in these groups, there are perhaps from 35 to 45 accidents that do not disable the employee beyond the remainder of the day, and of these fraction-of-a-day accidents the Bureau has compiled no statistics. Information revealed by the reports is to the effect that falls of roof and coal in bituminous coal mines are responsible for 28 per cent of the temporary injuries to underground workers and 33 per cent of the days lost from all temporary injuries underground; they also indicate that falls caused 59 per cent of the deaths from all causes underground. Figures compiled by R. N. Hosler, of the Pennsylvania. Mine Rating Bureau, and covering accidents in bituminous; minis in that State, chow that 61 per cent of the deaths underground during the years 1917-1921 wore due to falls. Neither of these percentage figures includes deaths in major explosions; figures for all bituminous mines in the United States during the five years 1920-1024, inclusive of deaths in major explosions, show that 52 per cent of the deaths underground and in shafts were due to falls of roof and coal.

Jan 1, 1925

By Thomas M. Barczak

Longwall operators are again pushing the envelope in terms of life expectancy for longwall shields. State-of-the-art shields are now expected to last more than 60,000 loading cycles, twice the life expectancy compared with those of a decade ago. A review of trends in shield design shows that shields continue to increase in both size and capacity. Some state-of-the-art shields now weigh over 30 tons and provide up to 1,200 tons of support capacity. Although life expectancy has increased and modern shields are structurally more reliable, premature failures do still occur. This paper provides an engineering and operational assessment of shield design and provides key points to observe in what causes premature shield failures. Design practices to improve structural margins of safety that will prevent premature failures from occurring are also examined. A survey of recent shield failures is provided, as well as trends in shield design and how they might impact the performance and longevity of a shield. Hydraulic failures are more common than structural failures. Although hydraulic failures occur on all aging longwall shields, they often go undetected for long periods, resulting in degraded support capacity that can lead to serious ground control problems. The fundamentals of shield hydraulics are described in order to evaluate hydraulic failures that plague all shields at some point in their service life, and practical methods to detect hydraulic failures are examined. The paper concludes with recommendations for inspecting damaged shields and safety precautions regarding their continued use.

Jan 10, 2000

By Clarence Hall, Charles E. Munroe

In accidents resulting from the use of explosives in metal mines and quarries in the United States more than 130 men were killed and 250 seriously injured during the calendar year 1913. More- over, an unknown number of miners suffered from the effects of breathing the harmful fumes and gases given off by the burning or the incomplete explosion of some explosive. Consequently, the Fed- eral Bureau of Mines, which is endeavoring to increase safety in mines and to abolish conditions that tend to impair the health of miners, is studying the kinds of explosives used in mining and the conditions under which these explosives can be used with least danger to the miner. Information about the different explosives used in coal mining and the precautions to be taken in using those explosives has been printed in Bulletin 17 and other bureau reports, the names of which may be found at the end of this bulletin. The bureau has not been able to give much attention to explosives used in metal mines and quarries, but has published some information about these explosives in Bulletin 48, "The Selection of Explosives Used in Engineering and Mining Operations"; Technical Paper 17, "The Effect of Stemming on the Efficiency of Explosives"; and Miners' Circular 19, "The Prevention of Accidents from Explosives in Metal Mining." This bulletin aims to give the metal miner and the quarryman information similar to that given the coal miner in Bulletin 17. In- flammable gas or dust is seldom, if ever, found in quarries or metal mines, and the danger from using explosives there is less than in coal mines; but, as the figures show, the number of men killed and injured yearly in accidents caused by explosives proves the need of both miners and mine officials striving to see that none but proper explosives are used and that these are used properly.

Jan 1, 1915

By N. S. Dalal, B. Jafarl, M. M. Suryan, V. Vallyathan

"The biologic events leading to coal workers' pneumoconiosis (C'WP) are not yet fully understood. There is no good correlation between toxicity studies or animal models with human epidemiologic and pathologic data. Several studies have shown that the severity and prevalence of the CWP in miners correlate strongly with the rank and type of the coal mined. However this has not been found to be the case with laboratory animal models or in vitro studies. In 1980 Russian scientists Artemov and Resnik suggested that the discrepancy may be related to the excessive amount of short-lived free radicals present in freshly generated coal mine dust. Because of their short life, such free radicals would be absent in the ""stale"" coal dust used in most animal experiments. To test this hypothesis we have undertaken a systematic study of the generation, reactivity with oxygen and biological significance of free radicals in coal dust.Electron spin resonance (ESR) was used as a technique for the direct detection of radical production and kinetics of decay. ESR signals from the newly generated radicals decreased with time on exposure to oxygen or when stored in biological buffers at a rapid rate. In vitro biological tests were carried out which suggest that the reaction between the newly generated radicals and oxygen plays a significant role in the sample's cytotoxicity.Materials and MethodsESR measurements were made at X-band (~9.7 GHz) using a computer-controlled Bruker ER200D ESR spectrometer. 11te two coals studied in detail were obtained from the Pennsylvania State University Coal Depository. These were, a bituminous sample, PSOC-1172 (72% carbon) and an anthracite sample, PSOC 867 (95% carbon). Coal particles of several millimeter (mm) dimensions were evacuated to a pressure of ~10-3 mm Hg typically overnight. Without exposure to air, these particles were ground in an agate mortar with an agate pestle for about 30 minutes and then sieved through a 20 \1111 mesh filter before ESR measurements or cytotoxicity studies. As an index of cytotoxicity, hemolysis was measured according to the method of Harrington, with minor modifications. Sheep erythrocytes (2%) were incubated with test samples at 37°C for one hour, and the hemoglobin released was quantitatively estimated photometrically. Additionally, release of alveolar macrophage enzyme lactate dehydrogenase (LOH) was estimated after incubation of the macrophages with the coal particles at different time intervals after the grinding. Enzyme activity was assayed according to the method of Wrobleski and LaDue and expressed as percent of enzyme released in 2 hours per million cells with 1 mg of coal."

Jan 1, 1989