Search Documents

By J. H. East, D. Harrington

Fires in metal mines have resulted in some of the worst disasters in American mining history insofar as loss of life is concerned. One fire caused the death of 163 miners and individual less spectacular fires have cost the lives of scores of workers. Metal mines are often very deep, and the men working on numerous levels far removed from direct communication with the surface. In many instances they cannot be warned quickly of an emergency or a mine fire by telephone or other usual method of communication, or by messenger, flashing lights, gongs, sirens, or whistles. Telephones are not paricularly effective as a means of warning unless placed at all strategic points and with attendants always on duty; though telephones well placed have a definite value in any well-pla.mied emergency procedure in mines of all kinds. Messengers are slow and men working in remote parts of a mine would not receive a warning quickly enough. Most metal mines are not electrically lighted, except at or adjacent to shaft stations and in principal haulageways, and this limits the effectiveness of flashing lights. Electric gongs and sirens or whistles have been tried as warning signals, but the sound is quickly deadened and does not travel upward into the stopes, especially those of an extensive volume. Shutting off the compressed air is by no means satisfactory as a warning, as not infrequently it is stopped accidently, so that it loses its value as an alarm. The introduction of water into compressed air lines is undesirable as a fire warning and necessitates considerable care, especially in deep mines; pressure-reducing valves must be provided to reduce pressure that otherwise would break connections or split the pipe. A quick, effective method of warning miners underground of the existence of an emergency requiring them to leave the mine immediately, such as a fire on the surface or underground, is provided by the introduction of stenches in the compressed-air lines. This method of warning is by no means experimental, inasmuch as it has been used successfully for many years in

Jul 1, 1943

By J. Gautam, T. Ong, W. E. Wallace, M. Keane, S. Xing, J. Harrison

"INTRODUCTIONOrganics extractable from respirable diesel exhaust soot particles by organic solvents have been known for some time to be direct acting frameshift mutagens in the Ames Salmonella typhimurium histidine reversion assay (Huisingh, et al). Upon deposition in a pulmonary alveolus or respiratory bronchiole, respirable diesel soot particles will contact first the hypophase which is coated by and laden with surfactants. To model interactions of soot and pulmonary surfactant, we dispersed soots in vitro in the primary phospholipid pulmonary surfactant dipalmitoyl glycerophosphorylcholine (lecithin) (DPL) in physiological saline. We have shown that diesel soots dispersed in lecithin surfactant can express mutagenic activity, in the Ames assay system using S. typhimurium TA98, comparable to that expressed by equal amounts of soot extracted by dichloromethane/ dimethylsulfoxide (DCM/DMSO)(Wallace, et al, 1987). Here we report additional data on the same system using additional exhaust soots and also using two other phospholipids, dipalmitoyl glycerophosphoryl ethanolamine (DPPE), and dipalmitoyl phosphatidic acid (DPPA), with different ionic character hydrophilic moieties. A preliminary study of the surfactant dispersed soot in an eucaryotic cell test system also is reported.MATERIALS AND METHODSSoots D4 and D6 were collected at two different times as scrapings from the exhaust pipe of a diesel tractor-trailer immediately after the engine was stopped. Surfactant dispersions were made by ultrasonic probe sonicating 25 mg of commercially obtained DPL, DPPE, or DPPA into 1O ml of O.85% physiological sterile saline (PSS) for 10 min at 40 watts power. For surfactant dispersions, 2.5 mg soot was mixed into 2.5 ml of the appropriate phospholipid dispersion. Mixtures were sonicated by 40 watts sonicator probe for one min, then incubated in the sonicator water bath for 30 min at room temperature; the mixture was then incubated for one hour at 37C while being rotated continuously. Dilution series were made with saline. For solvent extraction, 2.5 mg soot was mixed into 2.5 ml of DCM and incubated in a sonicator water bath for 30 min at room temperature. The sample was then mixed with 2.7 ml DMSO, placed in a dry bath at 45C, and the DCM evaporated under a stream of nitrogen gas until 2.5 ml of liquid remained. Ames salmonella/microsome assay utilizing TA98 for frameshift mutation was used for mutagenicity testing, with and without S9 activation, as described by Ames et al (1975). Unfiltered sample extractions or dispersions were preincubated with tester cells for 90 min at 37C : 0.1 ml of sample was mixed with 0.5 ml of PSS, or of S9 mixture, and 0.1 ml of an overnight TA98 culture incubated samples were then added to 2 ml of top agar supplemented with biotin and a trace amount of histidine, and overlayed onto Vogel-Bonner minimal media plates. After 48 hours incubation at 37C, revertant colonies were counted. Solvent controls were DMSO, DPL, DPPE, DPPA, and saline. Positive controls were trinitrofluorenone (1 ug/plate), for samples not treated with S9, and 2-aminoanthracene for S9 treated samples (2.5 ug/plate). All samples were assayed in duplicate. Sister chromatid exchange (SCE) assay was performed, following Lett, et al (1981), using V79 cells, of Chinese hamster pulmonary fibroblast origin. Stock diesel sample suspensions were made as 10 mg soot/ml DPL suspension, or 20 mg soot/ml in DMSO. Aliquots of these soot preparations were added to 15 ml of culture medium per sample flask to result in concentrations of 25, 50, and 75 ug soot/ml medium. After 12 hours incubation, 200 ul of 25 uM 5-bromodeoxyuridine (BrdU) was added to each flask. After another 35 hours incubation, 200 ul of 10 ug/ml colcemid were added; and the cells were harvested three hours later. Cells were swollen by hypotonic saline, and fixed twice with methanol/acetic acid, and burst on microscope slides. Cells on the slide were stained with Hoechst 33258, exp"

Jan 1, 1990

By Mark S. Stagg, Virgil J. Stachura, John W. Kopp, David E. Siskind

The Bureau of Mines studied airblast from surface mining to assess its damage and annoyance potential, and to determine safe levels and appropriate measurement techniques. Research results obtained from direct measurements of airblast-produced structure responses, damage, and analysis of instrument characteristics were combined with studies of sonic booms and human response to transient overpressures. Safe levels of airblast were found to be 134 dBL (0.1 Hz), 133 dBL (2 Hz), 129 dBL (6 Hz), and 105 dB C-slow. These four air- blast levels and measurement methods are equivalent in terms of structure response, and any one could be used as a safe-level criterion. Of the four methods, only the 0.1-Hz high-pass linear method accurately measures the total airblast energy present; however, the other three were found to adequately quantify the structure response and also represent techniques that are readily available to industry. Where a single airblast measuring system must be used, the 2-Hz linear peak response is the best overall compromise. The human response and annoyance problem from airblast is probably caused primarily by wall rattling and the resulting secondary noises. Although these will not entirely be precluded by the recommended levels, they are low enough to pre- clude damage to residential structures and any possible human injury over the long term.

Jan 1, 1965

By Russell C. Frith, David C. Oyler, Dolinar Dennis R., Christopher Mark

Unusual circumstances may require that a longwall retreat into or through a previously driven room. The operation can be completed successfully, but there have been a number of spectacular failures. To help determine what factors contribute to such failures, a comprehensive international database of 131 case histories has been compiled. The cases include six failures where major rock falls occurred in front of the shields, and seven even more serious failures involving major overburden weighting. The case studies suggest two types of room failure mechanism. The first is a roof fall type failure caused by loading of the immediate roof at the face as the fender or remnant longwall panel narrows. The second is an overburden weighting type failure caused by the inability of the roof to bridge the recovery room and face area, and affecting rockwell above the immediate roof. The data indicate that the roof fall type of failure is less likely when intensive roof reinforcement (bolts, cables and trusses) is employed together with higher-capacity shields. The overburden weighting failures, in contrast, occurred when the roof was weak and little standing support was used. Weighting failures were not greatly affected by the density of roof reinforcement. In one of the overburden weighting cases, in a Pittsburgh coal bed mine, stress cell, convergence, bolt load and extensometer data have been used to analyze the failure in detail. Key words: coal mining, ground control, longwall, recovery room.

By H. Robert Ensminger

As a result of the new mining law implemented in August 1985 and the programs conducted by the Institute Ecustoriano de Mineria (INEMIN), which was created by this legislation, there was considerably greater activity in the nonfuels mineral sector during 1986. Over the next 2 years, INEMIN will be developing a national mining plan that will guide Ecuadorean mineral development for the balance of this century. As stage one of INEMIN's mineral study, historical records were reviewed and 300 abandoned mines and 1,200 unexplored mineral deposits were available for further investigation. In 1986, INEMIN established 5 branch offices and negotiated 250 new mining contracts with foreign companies valued at $16 million. Despite all this activity, INEMIN officials estimate that 100,000 square kilometers remain available for claim staking. Technical assistance contracts were signed with Belgium, the Federal Republic of Germany, Italy, Spain, and the United Kingdom, to assist in a variety of assignments ranging from helping prepare the national minion plan to the development of industrial mineral deposits.

Jan 1, 1988

By Oliver Bowles

As the preface states, this bulletin is the fourth of a series of re- ports by the Bureau of Mines on different phases of quarrying in the United States. The first part of the bulletin describes the chief types of cements, the growth of the cement industry in this country, and the character of the raw materials used. The bulk of the report deals with quarrying methods and equipment, and gives especial attention to drilling and blasting; a chapter on rock mining and one on pros- pecting are included. Methods of manufacture are mentioned briefly, as that subject, except as related to quarrying, lies outside the scope of this report; but transportation methods and the effects of the man- ner of mixing the materials at the quarry or crushing plant on quarrying methods are discussed.

Jan 1, 1918

By E. S. Longfellow, S. H. Katz

Poisonous hydrocyanic acid gas (HCN) is sometimes evolved in dangerous quantities from cyanides used in metallurgical and chemical operations. This gas is much used for fumigating buildings, ships, greenhouses, and such commodities as grain and cotton to destroy rats, mice and insect pests. Wherever cyanide fumes are evolved, thorough ventilation is necessary in order to render the sur- rounding air safe to breathe. Many persons have been killed by entering tanks and fumigated places too soon, and a simple test for this gas would promote safety. In view of the need for an easy method for quantitatively determining HCN in air, the three color reactions used originally for testing HCN in solution tions *** were modified and adapted. The reactions employ (1) picric acid (CH(NO2)3OH) which is yellow but combines with hydrogen cyanide to form a red- purple dye, isopurpuric acid****; (2) phenolphthalin (CH1604), which is a reduc- tian product of the phenolphthalein (CH4) used for acid indicator, this colorless substance is oxidized***** by presence of HCN to pink colored phenolph- thalin; and (3) guaiacum which oxidized from colorless to blue******. Phenolph- thalin and guaiacum require the presence of copper compounds which catalize the color formation by reduction of cupric cyanide. The chemical processes involved *Associate physical organic chemist, Bureau of Mines, Department of the Interior. **Assistant gas chemist, Bureau of Mines, Department of the Interior. 2014 20 *** Kohn-Abrest, E., Notice toxicologique sur les gas: Arnales des Falsifica- tions, vol. 8, 1915, pp. 215-35. (Tested air with picric acid and guaiacum papers). **** Élasiwietz, H., Ueber eine neue Zersetzungsweise der Trinitrophenylsaure: Anal. der Chemie, vol. 110, 1859, pp. 289-303. ***** Weehuizen, F., Phenolphthalin as reagent for HCN: Pharmaceutrisch weekblad, Utrecht, vol. 42, 1905, pp. 271-2. Abstract, Jour. Chem. Soc., vol. 88, part 2, 1905, p. 489. ****** Schonbein, C. F., Ueber den thatigen Zustand der Helfte des in dem Kupfer- oxydenthaltenen Sauerstoffs und ein darauf beruhendes hochst empfindliches Reagens auf die Blausaure und die loslichen Cyanmetalle: Jour. fur. Praktische Chemie, vol. 106, 1869, pp. 263-70.

Jun 1, 1923

By D. A. Hill

Introduction The fields of an infinite line source in the presence of a conducting half-space have been examined by Wait and Spies (1971). In any real communication link using a current-carrying cable for the transmitting antenna, the cable is of finite length. Here we examine the fields of a finite length cable carrying a constant current in the presence of a homogeneous conducting half-space. The constant current assumption is valid at sufficiently low frequencies when an insulated cable is grounded at the end points (Wait, 1952; Sunde, 1968). Here we examine both surface and buried cables since both downlink and uplink communication links are of interest. Also, we examine both frequency and time solutions since either CW or pulsed communications may be used. Finally, it is necessary to include both magnetic and electric field solutions since reception could be with either loops or dipoles. Since the finite cable solution is more complicated than both the infinite line source and the short dipole solutions, we explore under what conditions a cable appears to be either infinitely long or very short. Some special cases, such as- the low frequency limit, permit analytical solutions which exhibit the dependence on various parameters, such as cable length, quite clearly. Frequency Domain Subsurface Fields The geometry of a line source of length 2[l] located on a conducting half-space with the observer in the half-space is shown in Figure 1. The fields

Jan 1, 1973

By M. M. Tilman

The Bureau of Mines investigated the precipitation strengthening of lead¬-base alloys containing 0.5 through 4 weight-percent combined Cd plus Sb. The Cd and Sb were alloyed in a 1-to-1 atomic ratio which maintained compositions along the quasi-binary section Pb-CdSb. Tensile properties, creep rates, and stress-rupture values were obtained on alloys in the aged condition. The highest tensile strength was observed in an alloy of Pb-3 CdSb, After aging for 6 months at 90°±3° F, this alloy had a mean tensile strength of 8,950 psi with 15-percent elongation. An aged alloy of Pb-1 CdSb exhibited a steady state creep rate of 1.2 X 10-3 percent per day at a stress of 500 psi and a temperature of 90°±3° F. Times to rupture at stresses up to 4,000 psi and at a temperature of 90°±3° F were obtained for some compositions.

Jan 1, 1970

This chapter analyses the parameters influencing initial design of communication systems, for new mines and upgrading existing systems. Paragraph 5.2 outlines those variables that must be taken into account during the design stages of a new wired phone system. Recommended features, general requirements, and how they can be implemented are treated in this section. Paragraph 5.3 describes ways of improving or extending the range of trolley carrier phone systems and pager phone systems already installed in the mine. 5.2 New Phone System Design The task of designing an adequate communication, control, and monitoring system for an underground mine must be addressed on a system basis. In addition to insuring that effective voice communication is established, any new system should take into account present and future requirements of remote control and monitoring functions. Chapter 4 illustrated the drastic savings in response time that can be realized when remote control and monitoring are integrated into the overall communication system. The importance of including control and monitoring in the overall design plan for any system cannot be overemphasized. Because each mine is unique, and thus usually has its own special operating characteristics and communication requirements, there is no such thing as "the one best system" to meet the requirements of all mines. The optimum communication, control, and monitoring system for a mine must be one that has been tailored to meet the special requirements of that particular mine. Factors that must be considered during system design include- a. Type of mine and mining methods (low- or high-seam coal, deep hardrock mine, stope caving, longwall, room and pillar, etc.). b. Maximum number of working sections. c. Expected mine growth rate and eventual maximum size. d. Haulage methods (tracked trolley, diesel, belt, etc.). e. Underground power distribution system (dc, ac, or both). f. Features desired (two-way radio paging, private line capability for emergency use, etc.). g. Redundant or backup systems for use during outages of the normal system. Although no two mines are alike, the following items have been established as the main characteristics desired for any underground communication system: 1. Multiple Communication Paths to Outside--the objective here is to give all telephones a second method of communicating with the surface. 2. Audible Emergency Signaling--the communication system provides the main means of alerting miners during emergencies. The system should include means to broadcast distinct audible signals for emergency signaling. Initiation of these signals should probably be controlled from. a central outside point, such as a surface control room. 3. Emergency Override--provisions should be included to permit any conversation to be overridden with emergency communication. 4. Selective Area Page--as mines grow larger it is apparent that the entire telephone system paging mode need not be activated each time a call is initiated. When the general area of a

Jan 1, 1984

By D. Harrington

In general, mining is carried on underground, that is, in confined places where it is difficult to obtain adequate lighting and frequently in rock strata requiring much care to prevent caving. Moreover, explosives must be used in mining with the numerous hazards associated with them, and some mines give off explosive or irrespirable gases; also, ma- chinery must be used, usually under conditions much more hazardous than on the surface. These and many other considerations cause mining to be probably the most hazardous occupation in which large numbers of our fellow countrymen are employed. Prevention of accidents in the mining industry is far more complicated than in surface industrial work, even of the more hazardous types, because the different elements that enter into possible accident occurrence are ascertained more readily above ground and suitable action can be taken against them; moreover, errors in connection with prevention of accidents in surface industrial work usually affect only one or, possibly, a few persons, while in zines one human error may readily cause an explosion or other untoward occurrence resulting in the death of scores or even hundreds of persons. This difficulty in the prevention of accidents in and around mines is well-known, and most countries and States have regulations to guard the safety and, to a much smaller extent, the health of workers in mining and allied industries. In general, the State laws and regu- lations regarding the welfare of mine workers are merely a skeletonized outline of some more or less fundamental minimum requirements and are far too general to do much more than suggest some procedure which may or may not be safe or healthful. Most of them are grotesquely out-of-date as applied to present-day conditions, and none of them is adequate to protect life, limb, health, or property. Unquestionably, there is great need for a closer correlation of the laws and regulations of the various States with regard to safety in the mining and allied industries, and while mining conditions vary far too much for a standardized mine safety law applicable to all of the States, on the other hand there are numerous standard and fairly fundamental safety pro- visions which apply to all mines and which should be embodied in the mining codes of all States. Undoubtedly, these standardized safety requirements would be opposed by a consider- able part of the industry, but the ultimate effect would be beneficial to the owners, work- ers, and the general public. For many years progressive mining companies in the United States have not been satisfied to operate only within the meager safety requirements of the State laws or regulations and have adopted additional and far more effective safety procedure of their own, although com- plying also with the State laws and regulations. As a result of this forward-locking policy, zany of these companies have made astonishing progress in the reduction of accidents.

Dec 1, 1935

By A. B. Hooker, L. C. IlsLey

"Field inspections and data relative to the use of rubber-sheathed trailing cables in mines show that much cable is ruined or its probable life shortened by being overheated in service.The length of cable required to make connection from a source of supply to a machine at the face workings may be 100 to 500 feet. As a rule, the cable is carried on a reel and unreeled as required; and thus in most cases soma of the cable is not removed from the reel. The overheating generally occurs in that part of the cable which is left on the reel.Factors that determine the heating of trailing cables are:1. The size of the conductors in the cable.2. The maximum energy to be supplied through the cable, based upon the horsepower of the motor and the degree to which the motor is loaded.3. The voltage of the supply and the variation of the voltage at the receiving end.4. The time length of current flow and whether continuous or intermittent.5. The kind of current (direct or alternating).6. The amount of ca· le left or the reel.7. The type of cable used.8. The kind of reel used.In connecti0n with an investigation of the general performance of rubber-sheathed trailing callas, the Bureau of Mines has made a limited study of some of these factors, including the following points:"

Jul 1, 1931

By J. W. Town

The Bureau of Mines studied the effects of reducing gas composition, tem-perature, and superficial gas velocity on the regeneration rate of alkalized alumina. Regeneration was assumed to follow the simple first order reaction for removal of sorbed S02: dµ/dt = -Kµ. An Arrhenius relationship can be plotted, which shows an activation energy of about 75 kcal/mole for simulated reformed propane. The general effects of the individual gases can be described as follows: (1) CO and H2 produced rates proportional to their con-centrations, up to about 5 percent for each; (2) addition of CO2 had no effects on the regeneration rate by CO; (3) the regeneration rate by H2 was lowered by the addition of H2O while the regeneration rate by CO was increased by 0 addition; (4) H2S showed a positive effect up to concentration levels of about 2 percent and then produced a rapid negative effect; (5) carbonyl sulfate (COS) increased the sulfur content; and (6) propane was as effective in regenerating the loaded pellets as was simulated reformed propane.

Jan 1, 1971

This Information Circular from the National Institute for Occupational Safety and Health (NIOSH) documents and supplements the information presented in a series of workshops held during 2002 and 2003. The primary intended audience consists of all who are involved in developing and conducting miners' training. According to the Mine Safety and Health Administration (MSHA), mine operators reported 240,000 full-time equivalent workers and independent contractors reported 42,000 full-time equivalent workers working on mine property during the year 2000. Unfortunately, these workers have a relatively high risk of suffering serious work-related injuries and illnesses. The mining industry has the highest rate of occupational fatalities among all U.S. industries. The fatality rate is 30 deaths per 100,000 workers compared to 4.6 for all private industry (Morbidity and Mortality Week Report, 2001; NIOSH, 2002). Compared to workers in other industries, miners also have a relatively high rate of nonfatal lost-time injuries, and their injuries tend to be more severe (Bureau of Labor Statistics, 1999). Many miners are also exposed to significant health hazards, including coal and silica dust, diesel exhaust, and noise. More than 1000 U.S. miners die of lung disease each year (NIOSH, 1999). Mine safety and health professionals have long recognized training as a critical element of an effective safety and health program. Federal regulations (30 CFR, Parts 46 and 48) require mine operators to provide initial safety and health training to all new miners, as well as a minimum of 8 hours of refresher training each year. The time and money being spent to train U.S. miners is substantial, and so there is a strong and steady demand for new and better mine training materials and methods. A growing concern among mine safety professionals regards the training of new workers. A major change in the mining workforce is anticipated within the next decade. In major segments of mining, especially coal, relatively few workers have been hired since the 1970's. Thus, as an entire cohort of miners in the current workforce nears retirement, the replacement of these employees will require an influx of new workers. New miners may be young people who lack the ability to recognize and respond to mining hazards in an appropriate manner. They may also have had different educational experiences than their older counterparts. Many safety professionals believe that these two cohorts require different approaches to training. The papers in this report should help prepare mine trainers for the changes about to occur in the workforce and acquaint them with strategies they can use to enhance the effectiveness of their training. The first three papers present basic principles for teaching adults. The five remaining papers are intended to illustrate how these principles can be applied to the development and imple¬mentation of effective training for miners. Below is an overview of these papers. 1. Kowalski and Vaught review the process and principles of adult learning. The learning model they present includes a discussion of goals, content, delivery, assessment, and remediation. Adults are viewed as active learners, experienced-based, expert in their own right in specific areas, independent, real-life centered, task-centered, problem-centered, solution-driven, skill-seeking, self-directing, and internally and externally motivated. Basic aspects of curriculum development are briefly reviewed. For further information about adult learning, see Camm and Cullen's paper. 2. Mallett and Reinke's first paper discusses issues related to training new miners who have recently or will soon be entering the mining workforce. These new generations of miners have different learning style preferences and training needs than Baby Boomers and other older miners. Even trainers who have been highly effective in the past should reassess their training styles and their classroom materials to determine if they are prepared to meet the needs of these young new workers. This paper provides information that will help mine trainers communicate across the generation gap. 3. Mallett and Reinke's second paper provide an overview of training evaluation. Trainers and decision-makers are given a framework for planning and assessing training evaluation strategies. The authors present Kirkpatrick's (2001) model of evaluation categories and discuss how to start an evaluation plan and various ways to collect data. They do not provide detailed instruction in evaluation methodologies, but give trainers a review of the things they need to consider when developing an evaluation plan. A good evaluation plan can inform revisions to a training course, assess trainee learning, and/or answer managers' questions about program effectiveness. 4. Brnich, Derick, Mallett, and Vaught discuss a technique for incorporating worker participation into fire prevention and safe equipment operation training. This technique involves development of short (5 to 7 minutes) videotapes coupled with toolbox talks that ground the content of the videos within the context of a miner's workplace. An example of one of these training modules is presented, along with the results of an evaluation performed on its effectiveness at improving miners' understanding of what types of information they should be sure to communicate during a mine emergency. 5. Wiehagen, Conrad, Friend, and Rethi discuss on-the-job training (OJT) as a method for teaching miners safety and production skills. Much of the training is done by experienced workers. This paper describes how small investments can help improve the effectiveness of on-the-job training. Effective on-the-job training involves some structure and planning in the transfer of responsibility for task performance from the trainer to the novice. Assisting the trainer could involve helping develop up-to-date job analyses and offering strategies for teaching and evaluating job skills. This paper addresses organizational considerations supporting structured on-the-job

Jan 1, 2002

By 1980, the U.S. mining community had reached a broad consensus regarding coal pillar design. The pillar load could be estimated from tributary area theory, and the pillar strength from empirical formulas and laboratory coal strength testing. Then the growth of longwall mining required new thinking. Recently, powerful design methods have emerged from analysis of large data bases of real-world pillar successes and failures. These include the Analysis of Retreat Mining Pillar Stability (ARMPS), the Analysis of Longwall Pillar Stability (ALPS), the Mark- Bieniawski rectangular pillar strength formula, and guidelines for preventing massive pillar collapses. Sophisticated numerical models have also helped transform the pillar design landscape. In the process, our understanding of pillar mechanics has been greatly enriched. A new paradigm divides pillar failure into three categories:

"Correlatina Lung Crackle Usina Holographic lnterf erometryAli Afshari, MS, West Virginia University, 1989The Effect or Surfactants on Suppression of Non-Wettable ParticlesAli Alaboyun, MS, Mineral Engineering, The Pennsylvania State University, 1989Geochemical Characterization of Kerogem, ShaJes, and Coal .Refme ~ted with Allegheny Fonnationof Cases of Northern West VirginiaDick Andre, MS, West Virginia University, 1987Particle Concentrations in a Hazelton Inhalation ChamberShahram Bavani, MS, West Virginia University, 1985Use and Potential of Luer Holographic Interferometry and Subsidence Model Study of an Underground.Room and Pillar MineRichard Begley, MS, West Virginia University, 1984Development of a Mechanistic Model for Prediction of Subsidence in a Longwall MineRichard Begley, PhD, West Virginia University, 1990.Redesign of Micro-Orifice Unifonn Deposit ImpactorSteve Behm, MS, University of Minnesota, 1991A Fracture Mechanics Study of Crack Propagation Mechanism in Coal: The Mechanics of Fine FragmentFonnationZ. T. Bieniawski and R. Karl Zipf, Jr., Mining Engineering Department, The Pennsylvania State University,University Park, PA. Final Report, October 1, 1988A Mathematical Model for the Prediction of Ambient Dust Concentrations in Mine AtmospheresR. Bhaskar, MS, Mining Engineering and Operations Research, The Pennsylvania State University, 1984Spatial and Temporal Behavior of Dust in Mines-Theoretical and Experimental StudiesR. Bhaskar, PhD, Mining Engineering, The Pennsylvania State University, 1987Experimental Studies of Dispersion and Deposition of Fane Particles in a Wind Tunnel and Mine AirwayKlaus Bode, MS, Mining Engineering, The Pennsylvania State University, 1991Perf'onnance of the High Yield Technology PM - 100 - Particle 11ux MonitorRobert Caldow, MS, University of Minnesota, 1987Development of Improved Methods for Monitoring and Control of Diesel Particulate in an Underground CoalMineD. H. Carlson, B. C. Cornilsen, P. L. Loyselk, X. Shan and J. H. Johnson, Michigan Technological University,Houghton, Ml. Final Report, June 15, 1991"

Mar 1, 1992

By R. L. Montgomery

Heats of solution of cerium metal and cerium (III) chloride in hydrochloric acid were measured. The standard heat of formation of the aqueous cerium (III) ion at 25° C is -166.1 ± 0.3 kcal/mole. Heats of solution of cerium (III) chloride in hydrochloric acid are consistent with the existence of a complex CeC1++ having a stability constant of 1 and a heat of complexing of 5.4 kcal/mole.

Jan 1, 1962

By William D. Monaghan, Thomas H. Dubaniewicz, Kenneth L. Cashdollar

Emerging laser technologies are quickly gaining acceptance in the industrial workplace. Besides the risk of human exposure, one safety concern with the more intense lasers is the potential for ignition of flammable gases, vapors, dusts, fibers, or flyings often found in hazardous (classified) industrial settings. In underground coal mines, lasers are being considered for remote measurement of explosive methane gas. Current federal safety regulations for underground mines contain no specific guidance for evaluating the safety of optoelectronic components such as diode lasers. The National Institute for Occupational Safety and Health is conducting research to help provide a scientific basis for developing appropriate safety guidelines for optical equipment in the presence of flammable methane gas and/or coal dust. One phase of the study is an experimental evaluation of methane-air ignition by laser heated small particles. Minimum observed igniting powers for laser energy delivered by 200-, 400-, and 800-um core diameter fiber optic cables and directed onto selected targets in methane-air atmospheres were 0.6, L l, and 2.2 W, respectively. Comparisons are made with other ignition phenomena, including heated wires.

By John M. Gomes

Two methods for electrowinning tungsten from wolframite [(Fe,Mn)W04] were investigated. The first method, direct electrowinning from wolframite concentrate dissolved in molten salt mixtures composed essentially of various combinations of sodium phosphates, sodium borates, and sodium halides, yielded impure products. The second method was electrowinning from a halide-tungstate melt that was obtained from a high-temperature, two-phase extraction of tungstic oxide (W03) from wolframite. Electrolysis in electrolytes prepared from addition of sodium metaphosphate (NaPO3) and boric oxide (B2O3) to the halide-tungstate melt produced tungsten metal of 99.9 percent purity. Tungsten carbide (WC) was electrodeposited from the halide-tungstate melt when the melt was adjusted to contain 82 mole-percent NaCI and 6.0 mole-percent each of W03, sodium metaborate (Na2B204), and caustic soda (NaOH).

Jan 1, 1970

By R. V. Ramani, V. T. Burgos, J. A. McClay

Cost Data Library The data retained in the Cost Data Library is of a semi¬permanent nature in that it is held in storage for immediate use with the program although its contents may require periodic evaluation to maintain it in a current status. The library is composed of six arrays containing both technical and cost data. The following description of the library input system provides the information necessary to maintain an active storage file. Array POWERA: FORMAT (8F10.0) - contains the step groupings of the power rate schedule for power cost computations. Four input data cards are required to fill this storage area. Card Column 1 1 - 10 Demand in Kilowatts for the First Step of the Demand Rate Schedule 11 - 20 Demand in Kilowatts for the Second Step of the Demand Rate Schedule y 41 - 50 Demand in Kilowatts for Fifth Step of the Demand Rate Schedule 51 - 60 Maximum Demand Level for this Rate Schedule 61 - 70 Percent Power Factor for this Rate Schedule 71 - 80 Unassigned 2 1 - 10 First Step Demand Charge, $/Kw 11 - 20 Second Step Demand Charge, $/Kw 4¬ 41 - 50 Fifth Step Demand Charge, $/Kw

Jan 1, 1975