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By Thomas M. Barczak, Ron Smith

Steel liner plates, which are bolted together to form a shell, are commonly used to provide temporary protective linings in the tunneling industry to ensure the stability of the tunnel and safety of the workers until more permanent ground reinforcement can be installed. As the ground deforms to try and close the opening, the liner plate is radially stressed, and by deforming redistributes these loads back to the surrounding insitu earth. Grouting behind the plates is done to fill any voids and ensure uniform contact to the strata around the back of the plates. Another function of the liner plate in some applications is to act as a platform or structure for the mining machine to react against in order to develop the necessary forward thrust to be able to excavate the face. In this case, the liner plates are loaded axially as a horizontal column of bolted liner plate rings, creating a jacking force against the liner plate assembly. In general, the buckling strength of the plate sections determines the jacking force capacity. Historically, the jacking force capacity of tunnel liner plates has been theoretically determined by some simplistic equations developed from tests of single liner plates. Recently, full-scale tests on a complete circular section of bolted liner plate ring segments have been conducted in the NIOSH Safety Structures Testing Laboratory using the unique Mine Roof Simulator to apply controlled loading in a manner that simulates the real world environment. Due to the unique size and capacity of the Mine Roof Simulator, these are believed to be the first full-scale tests conducted on the jacking force capability of tunnel liner plate rings. These tests indicate that the previously used theoretical equations tend to over predict the jacking force capacity of these tunnel liner plates. Unanticipated deformations in the field have been observed at loads below these theoretical design loads, therefore, a more accurate determination of the jacking force capability was needed. This report summarizes the full-scale test results, examines design parameters that impact the jacking force capability, and develops new mathematical models to improve the prediction of design loads.

By T. C. Higgins, J. S. Malesky, J. A. O'Connor

"INTRODUCTION This circular contains the story of a stubborn mine fire of electrical origin that started on the main haulage road of No. 59 mine of the Peabody Coal Co. and illustrates that sometimes serious fires can be fought by direct attack. The story also points out that the cost of such procedure can be extremely high, and it is better, therefore, to minimize the possibility of a fire of electrical origin by suitable over-current and line-fault protection. The lives of 163 men were saved by utilizing a recently sunk air shaft near active workings as an escapeway. These men could not have reached the older openings. Also described are the rescue of 75 additional men through another air shaft, sealing of the fire, attempted extin¬guishment with carbon dioxide, and the difficulties of fighting the fire and recovering the mine.A fire occurred shortly before 12 o'clock noon, August 15, 1949, in the No. 59 mine, Peabody Coal Co., Springfield, Ill. All 257 men underground escaped to the surface. One group of 75 men was delayed from escaping for several hours after the alarm was given because smoke and fire gases were circulating in a main return airway, which intervened between their working section and one air shaft, and also in the stairway compartment of the shaft. After being supplied with universal-type gas masks, or self-rescuers, these men were conducted from the mine by members of a State mine-rescue team and other mine employees. Six nine officials were hospitalized because of exposure to carbon monoxide during fire-fighting activities; all were discharged a few days afterward. Later, while doing work incident to fighting the fire, two men were killed, and several were injured by falls of roof and rib.The fire broke out after a collision of a loaded trip with four empty mine cars on the main east haulage entry. The mine cars were jammed against the trolley wire causing a sustained electric arc that ignited the wooden mine cars and the fire spread to the timbers and coal."

Apr 1, 1950

By H. P. Greenwald, G. E. McElrey

"Part IV.- The Resistance Caused by Right-Angle Bends. IntroductionThis paper deals with the fourth phase of an extensive research on coal-mine ventilation factors. A comprehensive report of the entire work is in course of preparation, but abstracts of the various chapters are being prepared in order to make the major results public as rapidly as possible. Parts I, II and III were issued as Serials Nos. 2621 (July 1924), 2647 (October 1904) and 2671 (March 1925) and dealt with the resistance of unobstructed entries, the resistance due to mine cars and, the resistance of timbered entries respectively.Description of the Tests With the last cutthrough between the two butt entries of the test section in the Experimental Mine open, the air flow was deflected, around two right-angle bends in the same direction, the butt entries being 50 feet center to center and approximately 6 by 9 feet in cross section. Each bend had a dead end opening off of it; that at the first bend was in the direction of flow and that at the second bond was at right angles to the flow. For a primary test condition the inner corner of each bend was trimmed square and the dead ends were closed off with board brattices set flush with the line of the cut-through.The two corners of the first band were, then modified both independently and in conjunction. Various modifications of both bends in conjunction were also tested with rather surprising results as to the effect of conditions at the first bend, upon the pressure losses at the second. To confirm the theory developed to fit these results a series of tests were made to give a direct comparison of the -pressure losses as between two bends with the air flow deflected in the some direction at each and with the air flow deflected in opposite directions. The former is designated ""double"" and the latter a ""reversed"" right-angle bend. This series of tests was conducted, however, on the bends at one of the intermediate cutthroughs at which the flow could be deflected us either direction at the second, bend. Here also the average cross-section was 6 by 9 feet and the bends were 50 feet apart."

Jan 1, 1928

By W. J. Fene

"The prevalence of accidents in the coal-mining industry has prompted a study of the workmen's compensation laws of the various States and the statistics of accident costs, for the purpose of explaining to operators how the compensation laws are regulated and to show the cost of accidents.The subject of compensation laws and accident costs is by no means new, but the prevalence of coal-mine accidents would indicate that the mine operator in general is not thoroughly conversant with their importance. Unquestionably, compensation laws are a large factor in promoting accident prevention, and it is believed that a greater measure of success would be accomplished in preventing accidents if all mine operators were fully aware of their important bearing on the cost of production.Many operators seem to be indifferent to accident occurrence; possibly they do not real¬ize the seriousness of the accident hazards that exist in their mines, even after the hazards are brought to their attention. There is no question that material financial advantages are to be gained by the prevention of accidents and it would appear that when these advantages are thoroughly understood, operators would be anxious to eliminate, insofar as is feasible, conditions likely to cause accidents.The unsettled state of the mineral industry and the irregular operation of mines during the past several years has probably been an important factor in influencing the apparently indifferent attitude of the operator. The chaotic conditions in the mining industry and especially in coal mining are unquestionably a factor that tends to increase accidents, just as mine idleness increases roof hazards and results in deterioration in mechanical, electrical, and haulage equipment, and promotes disorganization of the personnel. During such times greater efforts should be exerted toward the prevention of accidents because of these increased hazards and of the financial advantages brought about by the various savings to be effected when mine accidents are held to a minimum.This report on accidents in the coal mines of Pennsylvania was made possible largely through the cooperation of William J. Maguire, director, Bureau of Statistics, Pennsylvania Department of Labor and Industry, and Rush N. Hosier, superintendent, Coal Mine Section, Pennsylvania Compensation Rating and Inspection Bureau, who made available their records and extended much assistance and numerous courtesies during this study."

May 1, 1932

This book has employed miners' narratives to illustrate basic concepts about the escape process. One of the most powerful means by which people make sense of their experiences is through the telling and internalization of stories [Bruner 1990]. By couching one's own and others' motives and actions in terms of a coherent narrative, a person is able to learn from mistakes and plan future behaviors that may help ensure survival. A growing body of research suggests that decision-making skills used to deal with emergency situations can be taught and assessed by simulations based on narratives from the real world [Bransford et al. 1986; Brecke 1982; Brener 1984; Connolly et al. 1989; Halff et al. 1986; Jones and Keith 1983; Lacefield and Cole 1986]. Such techniques have been used to address the decision-making of medical personnel, civil and military flight crews, and even people involved in broader life events such as political and military situations [Babbott and Halter 1983; Dugdale et al. 1982; Farrand et al. 1982; Gilbert 1975; McGuire 1985; McGuire et al. 1976; Flathers et al. 1982; Giffin and Rockwell 1984; Jensen 1982; Janis and Mann 1987]. Given the validity of this method of study and the promise it holds for helping people improve the quality of their responses to nonroutine occurrences, it is perhaps surprising that there have been no studies of emergency decision-making among blue-collar workers prior to those conducted by the present authors and their colleagues. The purpose of this chapter is to describe underground coal miners' decision-making performance on a table-top simulation whose problem structure is derived from interviews with a group of eight miners who escaped from the 5 Left section at Brownfield Mine. The exercise was constructed by a panel of domain experts (mine safety and rescue personnel) with the assistance of an educational psychologist. The simulation includes actual predicaments with wise and unwise decision alternatives that, in the opinion of these domain experts, are characteristic of such escapes. Results reported in this chapter are the scores of a sample of experienced mine workers who completed the simulation. Because the exercise is a series of objective performance tasks coupled with detailed and immediate feedback, this simulation can be used to teach and refresh critical escape skills, as well as to provide data concerning the proficiency of miners at the time of exercise administration.

Jan 1, 2000

Objective To develop and evaluate the effectiveness of safety training tools specific to underground metal/nonmetal mining. Background In a series of stakeholder meetings held in the western United States beginning in 1998, participants identified a critical lack of appropriate training materials applicable to metal/nonmetal mining. Participants in the meetings provided many insights into what types of training materials are most effective in dealing with both experienced and inexperienced miners. Most important was that the materials should be realistic and interesting and that some way should be found to capture the wisdom and expertise of older miners before they retired. In response, training videos that focus on safe practices during the mining cycle are being produced. Two videos one on handling explosives underground and one on identifying roof hazards and proper scaling techniques were completed during1999, and a third video is now available. This video, entitled “Ground Support...It’s Important, or Miner Mike Saves the Day,” presents information on why ground supports work and how to install them properly. Approach The new video, “Ground Support…It’s Important,” presents a scenario in which two young miners make a bad decision to leave some supports out in order to catch up in their mining cycle. An expert miner, “Miner Mike,” sees this potentially disastrous situation and educates the young miners about what could happen if they continued to leave supports out. He introduces the young miners to several expert miners, who explain how to install different types of supports correctly, as well as share what experience has taught them over the years. How It Works All footage was taken in operating, underground mines, using14 experts to provide the teaching. Because of the wide variety of supports used underground, it was necessary to focus on those types more common to hard-rock mining. While more complex support systems, such as shotcrete and cable bolts, are mentioned, detailed material is not included. In the course of educating young miners Jeff and Jason, Miner Mike provides information on— •Why supports are necessary in underground mines. •The main types of supports commonly used in underground hard-rock mines. •How supports work. •How holes for bolts are drilled correctly using jacklegs, drill jumbos, and bolting jumbos.• How wire mesh, wire panels, metal mats, and different types of bolts, including mechanical bolts, friction bolts, grouted bolts, and cable bolts, are installed properly. •How to recognize that supports have failed and what to do about it.

Jun 1, 2000

Homans [1950] offered a working definition of group that is useful for this research: "We mean by a group a number of persons who communicate with one another often over a span of time, and who are few enough so that each person is able to communicate with all the others, not at secondhand, through other people, but face-to-face." This chapter begins with a discussion of the group concept in reference to the hypothesized escape groups mentioned earlier. It then moves to an examination of analysis techniques used by the authors. Finally, the subjects themselves are profiled according to their demographic characteristics. The Nature of Groups Warriner [1956] took a realist approach to understanding groups: "(1) the group is just as real as the person, but (2) both are abstract, analytical units, not concrete entities, and (3) the group is understandable and explicable solely in terms of distinctly social processes and factors, not by reference to individual psychology." Warriner's realist position merely holds that "group" occupies a different domain in which it is no more or less concrete than "person." At this group level the unit of analysis will be those relations that indicate social rather than individual behavior. It is possible to investigate these group properties empirically-if a researcher avoids confusing conceptual entities with concrete ones. Most people seem to accept that group attributes must somehow be inferred, but think personal attributes will be directly manifested, requiring little or no interpretation [Snizek 1979]. In other words, nobody would equate physical components of an underground working section with the actual work group, yet social scientists (as well as laypeople) very often confuse real individuals with notions of the person. In actuality, neither groups nor persons are directly disclosed to the senses; both are inferred by experience and observation. One can "see" a group just as clearly as one can "see" a person, given the proper perspective from which to do so. It is necessary, in developing this perspective, to begin with a sound definition of the thing being examined. Besides communication, or more generally, social interaction, Homans [1950] included three other components of group makeup. "Sentiment" is characterized as the feelings people tend to form about one another when they interact often. These feelings include not only friendliness and dislike, but attitudes such as approval or disapproval. A "norm" is an idea, held in common by group members, that specifies how people ought to behave in given circumstances. In lay terms, norms are simply those informal rules individuals abide by in order to get along together in social situations. Finally, "activity" refers to those things persons do with others. In work groups, as an example, many of the activities are cooperative and goal-directed.

Jan 1, 2000

The production of harmful pollutants from coal mines and/or from coal and associated strata has been a recognizable fact in the United States for over two hundred and seventy years. In 1698, Gabriel Thomas observed(l) that the colored water flowing from streams in this country was similar to that which flowed from the coal mines in Wales. Hence, water pollutants such as acid were being produced before any known coal mines were operating in this country. The coal mining industry has contributed to the increase of pollution by exposing large amounts of sulfide materials that enable the reaction of water, oxygen and sulfur containing materials to form acid. A map of the United States coal fields can be seen on Figure 1. The anthracite regions of Pennsylvania, although small when compared to the total reserves, have produced some of the country's major water problems. The map indicates the extent of bituminous reserves of the Appalachian and midwest regions. Also evident are the bituminous, subbituminous and lignite coal reserves in the west which have recently come into greater demand. Acid mine pollution is encountered in numerous states, but the major problem is found in the Ohio, Susquehanna, and Potomac River basins.(2) Most coal beds contain some sulfur which may be in the inorganic, sulfate, or sulfide form, and thus have the potential to produce sulfuric acid. However, much of the strata that overlays the coal beds also contains acid neutralizing materials. Therefore, the amount of acid produced depends upon the amount of both acid and alkali materials that dissolve in the water in any given mine. The common sources of sulfurous material in the seam or surrounding rock are generally called sulfur balls or "nigger heads" by the miners. Sulfur balls that have been observed(3) seem to be equally divided between those containing sulphuritic iron capable of producing sulfuric acid upon oxidation and those that are primarily calcium carbonate. It has been observed in many instances that two types of water, acid and alkaline, are being produced in the same mine. A study of the geological strata and a survey of subsidence, faults and sulfur balls will usually give some indication of why this happens. The reaction of pyrite (FeS2) with oxygen and water to form ferrous sulfate (FeSO4) and sulfuric acid (H2SO4) by a series of complex chemical interactions is well documented but not well understood.(4,5) However, it is well known that the reactions to form the acid cannot occur unless all three constituents are present. Since pyrite is inherent in most coal seams and air is needed to sustain the miner, the most logical answer is to eliminate water infiltration into the mine, or to remove it from the mine before acids can form.

Jan 1, 1970

Objective To reduce equipment operator exposure to respirable dust in enclosed cabs by examining the effectiveness of retrofitting air pressurization and filtration systems on existing cabs. Background Many types of heavy equipment are used in mining, construction, and agriculture. Most have enclosed cabs to protect the equipment operator from excessive dust and noise exposure. When the equipment is new, controls are normally implemented into the cab to keep these exposures at acceptable levels. However, as this equipment becomes older, many components of the enclosure deteriorate, such as gaskets and seals. This causes the effectiveness of the enclosed cab to be greatly reduced. Once this occurs, the equipment operator's dust exposure can increase to hazardous levels. In surface mining operations, elevated exposures to crystalline silica have caused an excessive incidence of silicosis. Approach A cooperative research study with a mining operation and a cab filtration company was conducted to evaluate the effectiveness of retrofitting an older surface drill with two controls to lower the drill operator's respirable dust exposure. These two controls were: (1) A good air filtering and pressurization system to ensure that clean air was delivered into the enclosed cab. Ideally, the incoming air filter should be 99% efficient in removing particles with an aero- dynamic diameter of 0.3 pm or greater from the airflow. (2) Sufficiently sealing the cab to develop a positive static pres- sure and ensure that dust was not leaking into the cab. This was done by plugging all holes and cracks and maintaining good gaskets and seals. To prevent wind from forcing contaminated air through holes in the cab, the cab's static pressure must be greater than the wind's velocity pressure. During the course of this research, it was found that a floor heater fan used in the drill during the winter months greatly increased the operator’s Respirable dust exposure. Problem Identification Four days of background dust levels were measured as a baseline for this research. These baseline measurements were taken in May 2000 when air temperatures ranged from 60° to 70° F. When this was completed, the two controls were implemented. The first control was to install an improved air filtering and pressurization system on the enclosed cab. This was composed of a two-stage prefilter, a blower, then the respirator-medium secondary filter. Since the secondary filter was on the positive side of the fan, all air delivered into the enclosed cab had to pass through this secondary filter. After the filtering system was installed, the cab was pressurized to a static pressure of0.01 inches of water (w.g.), which is still very minimal. The second control was to seal the cab. New door gaskets were installed, and all cracks and holes in the shell of the enclosure were plugged. This increased the cab pressurization to approximately 0.1 inches w.g.

Mar 1, 2001

By H. B. Humphrey, J. J. Forbes

"In accident prevention, a study of statistical data is necessary to determine primary causes of accidents to devise means to eliminate causes at the original sources. Explosions in coal mines of the United States during the 10 years ending December 31, 1931, ranked third in the causes of fatal accidents; they constituted 16.2 per cent of all fatal accidents in bituminous mines and 8.4 per cent of all fatal accidents in anthracite mines. A study of coal-mine explosions in Pennsylvania, with approximately 160,000 men employed in anthracite mines and about 145,000 in bituminous mines or about 205,000 out of -the approximately 525,000 men employed in all coal mines of the United States, should give information of value to all persons endeavoring to reduce or eliminate coal-mine explosions. This circular reviews explosions of gas or dust or of both in the coal mines of Pennsylvania to show the hazard of gas and dust, to point out the influence of certain factors in causing explosions, and to emphasize the efficacy of explosion-preventive measures.The data published annually by the State Department of Mines and of the United States Bureau of Mines were used in compiling the tables of explosions. Through the cooperation of W. H. Glasgow, secretary, Department of Mines of Pennsylvania, and his assistants, many doubtful cases were clarified, so that as far as recorded the history is comparatively complete. Figures used in compiling some of the tables were furnished by W. W. Adams, chief statistician, demographical division, United States Bureau of Mines.Anthracite in the Wyoming Basin of Pennsylvania was used locally by gunsmiths in 1755, by blacksmiths in 1769, and as domestic fuel in 1808.Mining and shipments developed slowly between 1806 and 1812, but more rapidly after that.Early mining along the outcrops gave essentially no trouble from gas, but by 1870, when State inspection was established, explosions were frequent; ventilation was crude and accumulations of gas were generally ""brushed"" or burned out.Table 1 lists 1,232 ignitions and explosions of gas in anthracite mines from 1870 to 1932, inclusive, every one of which was accompanied by loss of life. Some details are given of 110 representative cases in which five or more lives were lost or in which it appeared that some violence was present.During the period 1870 to 1932, inclusive, gas explosions caused 2,213 fatalities, or an average of about two deaths for each ignition or explosion. Records are not available as to the number injured in these and in other explosions where no deaths occurred, but from a study of explosion reports it appears probable that the number injured exceeds the number killed. In the 110 cases described, 599 were killed and 294 were injured. As shown in Table 2, fatalities from gas explosions averaged 8.3 percent of the total fatalities in Pennsylvania anthracite mines from 1870 to 1931, varying from 6.0 percent in 1931 to 13.1 percent in 1927."

May 1, 1933

By Ryron O. Pickard

"The Berkeley safety station of the U. S. Bureau of Mines was recently informed that a geologist was killed through entering an abandoned 90-foot exploratory shaft without making a preliminary test of the shaft atmosphere. He was one of a geological party which was investigating coal lands in California. The only light that he carried into the shaft was an electric flash light. After he had descended a short distance, one of his associates on the surface heard him exclaim, ""This place is full of gas, I am coming up"", He had no more than finished the remark when he was seen to lose his grip on the ladder and fall down the shaft. He was apparently weakened from impure air in the shaft, and could no longer suppers himself on the ladder. When his body was recovered, it was found that his neck had been broken by the fall.This is the ;second recent accident that has been called to the writer's attention where a life has been lost in abandoned exploratory workings; the other fatality being in Minnesota where a mining engineer was overcome while sampling a shallow pit in iron-ore formations. This engineer was on the bottom of the shallow pit and died before help could reach him. It was generally supposed that each of these deaths were due to poisonous gases, but the writer believes, after reviewing the information available, that death in both instances may have been directly caused by deficiency in oxygen.Frequently in the daily press there are items relative to lives being lost through cleaning out old wells, and as a general rule such accidents are also caused by impure atmospheres.In every abandoned shaft or pit, or in fact, any old working where the air has been stagnant for a considerable time, there is always danger of oxygen deficiency, as the oxygen which originally comprised one-fifth of the atmosphere may be appreciably replaced by gases that do not support life, usually by carbon dioxide (black damp) or methane (fire damp). Much valuable information on the subject of mine atmospheres, mine gases, and the effect of oxygen deficiency onthe human system is contained in Miners' Circular 14, ""Gases Found in Coal Mines"" by G.F. Burrell and F. M. Seibert; Technical Paper 122, ""Effects of Oxygen Deficincy on Small Animals and Men"", by G. A. Burrell and G. G. Oberfell; and ''Chit of Properties of Mine Gees"" by G. A. Burrell. These publications of the Bureau of Mines should be rent by all who are interested in the subject of this paper."

Nov 1, 1921

By Thomas L. Chapman

The San Manuel is a deposit of low-grade disseminated copper ore. It was brought to the attention of the government in October 1942 through an application to the Reconstruction Finance Corporation for a development loan, supported by a report by Henry W. Nichols. Nichols' sampling of two outcrops containing copper silicate and his geologic map indicated that a minable body of copper ore might be developed. The Federal Geological Survey was requested to examine the property. The Survey mapped the geology in March 1943 and cut a few check samples, which substantially confirmed Nichols' sampling of the outcrops and a few shallow workings. The geologists of the Survey recommended some test drilling by the Bureau of Mines. The property was examined by the author and Wm. D. Hughes, associate engineer of the Bureau of Mines on March 22 and 26, 1943, and a preliminary drilling campaign was recommended. Five shallow churn-drill holes totaling 1,480 feet were put down under the supervision of Chas. A. Kumke, one of the Bureau's engineers, from November 23, 1943, to January 13, 1944. This work indicated that the deposit extended deeper than the 350-foot depth attained in the deepest hole and might have very considerable areal extent. Additional funds were allotted, and the drilling contract was extended twice to a final maximum of 17,000 feet with 2,000 feet maximum depth of hole. Drilling was continued by the Bureau of Mines until February 2, 1945, when 15,844 feet of hole had been drilled. The Magna Copper Co. took options on this and adjoining property in September 1944 and commenced drilling with two machines. It also engaged the two contract drills used by the Bureau after it stopped drilling. It exercised its options in August 1945 and organized the San Manuel Copper Corp. to operate the property. That company is continuing to explore the ore body with six churn drills. Thomas Lyon took options early in 1945 on holdings adjoining the San Manuel property on the east and is operating two churn drills. Exploration up to the completion of the last holes started by the Bureau of Mines indicated a block of ore 3,100 feet long, 400 to 800 feet wide, and 500 to 900 feet thick, and averaging about 0.8 percent copper. Subsequent drilling showed that the ore body extends considerably beyond this block. The axis of the ore body strikes about N. 61° E. Copper minerals are disseminated in hydrothermally altered quartz monzonite and monzonite porphyry. Ore outcrops in two small areas over the northeast part of the block. Elsewhere the copper-bearing rocks are capped by Gila conglomerate, which thickens toward the west and south. Drilling showed that the ore is in a thick, tabular body with a steep dip to the south. The ore body lies near the surface in the northeastern part of the block. The south side of the block is much farther below the surface than the north side. There the upper part of the copper-bearing rocks is lightly mineralized, so that the hanging wall of minable ore lies deeper than the base of the conglomerate cap, which thickens southward.

Aug 1, 1947

By Thoms L. Chapman

The San Manuel is a deposit of low-grade disseminated copper ore. It was brought to the attention of the government in October 1942 through an application to the Reconstruction Finance Corporation for a development loan, supported by a report by Henry W. Nichols. Nichols’ sampling of two outcrops containing copper silicate and his geologic map indicated that a minable body of copper ore might be developed. The Federal Geological Survey was requested to examine the property. The Survey mapped the geology in March 1943 and cut a few check samples, which substantially confirmed Nichols’ sampling of the outcrops and a few shallow workings. The geologists of the Survey recommended some test drilling by the Bureau of Mines. The property was examined by the author and W. D. Hughes, associate engineer of the Bureau of Mines on March 22 and 26, 1943, and a preliminary drilling campaign was recommended. Five shallow churn-drill holes totaling 1,480 feet were put down under the supervision of Chas. A. Kumke, one of the Bureau’s engineers, from November 23, 1943 to January 15, 1944. This work indicated that the deposit extended deeper than the 350-foot depth attained in the deepest hole and might have very considerable areal extent. Additional funds were allotted, and the drilling contract was extended twice to a final maximum of 17,000 feet with 2,000 foot maximum depth of hole. Drilling was continued by the Bureau of Mines until February 2, 1945, when 15,844 feet of hole had been drilled. The Magma Copper Co. took options on this and adjoining property in September 1944 and commenced drilling with two machines. It also engaged the two contract drills used by the Bureau after it stopped drilling. It exercised its options in August 1945 and organized the San Manuel Copper Corp. to operate the property. That company is continuing to explore the ore body with six churn drills. Thomas Lyon took options early in 1945 on holdings adjoining the San Manuel property on the east and is operating two churn drills. Exploration up to the completion of the last holes started by the Bureau of Mines indicated a block of ore 5,100 feet long, 400 to 800 feet wide, and 500 to 900 feet thick, and averaging about 0.8 percent copper. Subsequent drilling showed that the ore body extends considerably beyond this block. The axis of the ore body strikes about N. 61º E. Copper minerals are disseminated in hydrothermally altered quartz monzonite and monzonite porphyry. Ore outcrops in two small areas over the northeast part of the block. Elsewhere the copper-bearing rocks are capped by Gila conglomerate, which thickens toward the west and south. Drilling showed that the ore is in a thick, tabular body with a steep dip to the south. The ore body lies near the surface in the northeastern part of the block. The south side of the block is much farther below the surface than the north side. There the upper part of the copper-bearing rocks is lightly mineralized, so that the hanging wall of minable ore lies deeper than the base of the conglomerate cap, which thickens southward.

Aug 1, 1947

By R. V. Ramani, A. S. C. Owili-eger

System Size N,NX Number of blocks in x-direction M,NY Number of blocks in y-direction NTIMES Number of systems to be simulated LENGTH Length of medium WIDTH Width of medium THICK Thickness of medium NZONE Number of material zones Medium Properties XPERM(I,J) Permeability in x-direction at the point (i,j) YPERM(I,J) Permeability in y-direction at the point (i,j) PHI Medium porosity T Medium temperature Gas Properties PURL, VISCOG Gas viscosity Z Gas deviation factor BETAG Gas compressibility coefficient Initial and Boundary Conditions IBC Initial and boundary conditions NPRESS Number of specified pressures NQUAN Number of specified quantities FACEP Face pressure RESEP Reservoir pressure

Jan 1, 1974

By L. C. Ilaley

The Buresa. ot Mines at its Pittsburgh Station conducted tests aa earl7 a.a 1911 looking into the satety of miniature electric bulba. The first teata were maie with bulbs euch as were being sold with the partly developed lamps then on the market. 'l'he.sa aarly teats demonstrated the da.nger of using minia.tu:re bulbs in explosive mine atmospheres unless the current that enet gized the glow!ng filament was in aome minner inter.N.ptecl if the glass surrounding the filanant should be broken.

Jun 1, 1922

By John Gross

The Alaska Station of the Bureau of Mines has recently conducted tests on two tailings from black sand which had been treated previously at the Station. The results of this previous treatment have be on given in a paper entitled "Recovery of Gold from Black Sand by Classifier Concentration." The gold in these tailings was intimately united with quartz, and was so finely divided that it could not be detected with the naked eye, nor even by P&nn ing unless the material was ground. Its fineness is further shown by the assºy result, which reported only lz per cent of the gold content as "metallics", Wºorea's the assay of the original sand reported 36 per cent of the gold as "metallics." The fact that the gold was in such fine particles, closely united with quartz, precluded further recovery by amalgamation without grinding. On the other hand, the small content present, as well as the lack of grinding appliances at the placer mines of Alasia, made it necessary that the material be cheaply handled if at all. With these facts in mind the experiments described below were undertake.n.

Oct 1, 1920

By A. A. Afshari, D. G. Frazer, C. F. Stanley

"INTRODUCTIONThe primary function of the lung, i.e. gas exchange, occurs in peripheral units termed alveoli• Diagnosis of lung dysfunction ls therefore dependent on techniques to evaluate the status of the peripheral airways. Since these airways and alveoli are very small, it is difficult to determine directly how they function or how the function is changing due to disease. Yet this unde1·standing is critical to the design of instrumentation to detect early changes in lung function due to disease.An interesting hypothesis describing one aspect of small airway function has been proposed by Frazer (1) as gas trapping due to the formation of menisci in the airways. An additional study (2) proposes that the breaking and possibly the formation of these menisci could generate lung sounds, i.e. crackles. These lung sounds were recorded by placing a microphone at the trachea of an excised rat lung. The lung was degassed and then inflated and deflated. At points along the path of inflation, lung sounds were recorded. However, determination of the origin of the sounds was not attempted due to the difficulties induced by contacting the lung st1rface with a microphone.The purpose of this paper is to describe a non-contacting, whole field technique to monitor and describe the movements of the lung surface during inflation - deflation cycles.HOLOGRAPHIC INTERFEROMETRYHolographic interferometry is a full field, non-contacting and non-destructive technique that measures deformations of an object with a sensitivity in the order of the wavelength of light. A laser beam is split, with one beam reflected from an object and the other used as a reference beam. Both beams combine to produce a hologram of the object on a photographic plate. The process utilizes the concepts of interference, i.e. the two wave amplitudes will add at the points where the difference in optical path lengths over the exposure period is zero or a whole number of wavelengths and will subtract at other points."

Jan 1, 1989

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

In lare-scal e blasting, it is customary to fire me.l'\Y shot.!:l simu1. taneously. The electric !atonators ara usually conneced in seies, ard are fired either from a power circuit or :from a blasting ma.chine with large capacity, operated by hand. "!hen :'::ri111; with a blasting ca.chine, trouble with missed shots has been freqi.,.ently e>:pert0nced.. Unit1:i:' thes ,:::rcu:ns tances, the shots that fail to fire are often a gr"up in the t.:E"nter r,f t>e series, Various explaz,.a.tions hs.ve been given as to the cause of the failurs. Tis paper covers a few tests made cy the electrical section of tl:.e Dti..'t'cau. cf Mines, wh;.r.;h may be helpful in understanding the -probable cuse of tl1e misfiring of c.:anter shots, Wh3tever th9 source ot the firir. current generator, magneto, or batter, the CUl"rent delivered th:·01.1.gh a shot-f:?·ing circu.it is determined by t.ae total resistance of ,;he clrcili +.; c:1nd all cure:it leaving th9 p,si tive terminal must return to tre negative te1-minal. If a. metallic circuit is well i1,.sul.:tted, praeti­ccl. l;1 a.ll of the t.'Urrent keepo within the circu.it; but in a. shot-!11·.irig ci.rc1li t, Nhere the ·.vires f:ll·e often 1n c.c,i.cact with the eru:"!ih as i11 wet holer., end whero the ins".lla.tion of the leg wires :i. inadecpa.te to prc·,ent lea.l.tage, the current ma.v tu.e v a.r ious pa the: thro-.. .. gh the nr r. earth.

Aug 1, 1922

By Geo S. Rice

"Three men lost their lives in the Black Diamond Coal Mine near Seattle, Wash., recently while wearing oxygen breathing apparatus. The press dispatches stated that these men lost their lives while practicing with the apparatus. Later reports stated that the men died while attempting to make a trip 1200 feet down a 25 degree slope which was filled with black damp, in order to measure the amount of water that had accumulated at the bottom of the mine, and the trip was attempted with oxygen in the tanks of the apparatus with dials indicating only 45 minutes supply. The oxygen in the tank was used up and the men therefore lost their lives from a deficiency of air to breathe.In spite of all the education and training done by the Government to prevent accidents, men are prone occasionally to take unnecessary chances. Every piece of apparatus, no matter how perfect, has its limitations. The Government, through the agency of the Bureau of Mines, has trained many thousands of miners in the use of mine rescue apparatus. The training has been given to all miners who requested it, and the Bureau has gone to the extreme of urging miners to join the rescue and first-aid classes. In spite of all the efforts of the Government, men occasionally attempt the impossible."

Jul 1, 1920

By Franxis Church Lincoln

"INTRODUCTION During September 1944, the Bureau of Mines undertook a program of investigation and limited exploratory drilling at the Last Chance mine, near the village of Arthur in Grant County, Wisconsin, as part of a general investigation of the zinc-producing area of southwestern Wisconsin when every effort was being made to increase the production of metals important to the Nation's war program.The Bureau's attention was directed, to the Last Chance mine when the operators discovered high percentages of zinc in an exploratory churn drill hole a short distance southeast of the mine. The ore was found in the Trenton Limestone, which underlies the ore horizon then being mined. To determine whether this discovery was important, and to demonstrate the possible extension of the ore the Bureau of Mines drilled five additional holes in the vicinity of the discovery.ACKNOWLEDGMENTSIn its program of exploration of mineral deposits, the Bureau of Nines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report."

Mar 1, 1947