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By Oliver Bowles

"The American Consul at Guatemala City reports that the Guatemala Marble Mining Company is preparing to operate a marble quarry about 13 miles from the railroad station of Zacapa, which station is a little over 100 miles from Puerto Barrios, the nearest port from which the product may be shipped. The deposit is extensive, and though somewhat broken up in places, great quantities of sound marble are available. It is claimed that the marble is equal in quality to the best product of the Italian Carrara quarries.Access to the quarry by rail is obtained by a spur track of the International Railways of Central America (Ferrocarril Internacional de Centro America) from Marmol, 3 miles south of Zacapa. This spur is about 5 miles long and terminates at the foot of the mountains. A double-track incline cable-way 2000 feet in length has been constructed to bring the marble down the mountain. From the top of the incline to the quarry there is a railway six miles in length over which the rock will be hauled by two side-geared Shay locomotives."

Mar 1, 1920

By D. W. Frommer

Laboratory mineral-dressing investigations were conducted on talc-bearing samples from Arkansas and Texas under the Bureau of Mines program of examinations and surveys, which is concerned, in part, with the improvement of conservation and utilization of domestic mineral resources. Two of the soapstones in question were successfully upgraded by flotation, utilizing stage additions of a frother and an amine to promote their talc content. The process could enable the producers to meet more rigid specifications of higher priced talc commodities. INTRODUCTION Talc is an industrial mineral with distinctive properties, such as softness, smoothness, large surface area in relation to mass, chemical inertness, and good retention as a filler, that make it particularly valuable to a number of industries. Sales to 6 industries -ceramics, paint, insecticide, rubber, roofing, and paper -consumed 84 percent of the domestic production of talc, pyrophyllite, and ground soapstone in 1952. Mine production in that year totaled 600,908 tons. Sales of crude and ground material were 593,147 tons valued at $11,347,317.2/

Jan 1, 1956

By Frank E. Cash

The iron-ore ranges in the Lake Superior district are the liarquette in Michigan, Menominee and Gogebic in Michigan end Wisconsin, and the Vermilion, Mesabi, and Cuvuna in Minnesota. These ranges produce about 85 percent of the iron ore mined in the United States. Accident experience in connection with this production is better than that of the regions producing the remaining 15 percent. Production and shipments vary slightly from year to year but closely approximate each other over a period of years. During the 4-year period 1940 to 1943, inclusive, 323,667,599 long tons of iron ore was shipped from the Lake Superior district.4/ Michigan and Wisconsin shipped 65,386,608 tons, or 20.2 percent of the total, and employed approximately 15,000 men; Minnesota shipped 258,280,991 tons, or 79.8 percent of the total, and employed approximately 10,000 men. The tons produced per man employed is much, greater in Minnesota than in Michigan and Wisconsin owing to the large open-cut production in Minnesota.

Jan 1, 1945

By Raymond P. Maloney

The Rhyolite mercury prospect is on the south flank of Juninggulra Mountain--a large rhyolite intrusive in the Kuskokwim River region about 36 airline miles northwest of Red Devil, Alaska. Bulldozer trenching by the Bureau of Mines exposed bedrock at intervals in a 2,000-by 3,000-foot area where previous prospecting by the owners had disclosed abundant float and several in-place stringers containing cinnabar in widely varying amounts. The additional trenching indicated that the mercury mineralization in the limited area investigated was confined to erratically distributed short stringers and to small lenses, occurring in discontinuous zones in numerous silica-carbonate dikes and sills or along their altered contacts with sedimentary rocks. The geologic relationship of the mercury-bearing silica-carbonate dikes and the nearby rhyolite intrusive is similar to that existing at several other mercury mines and prospects in the. Kuskokwim region. The depth of over-burden and the presence of permafrost were serious obstacles to bulldozer trenching, and only a comparatively small part of the mineralized area was thus investigated.

Jan 1, 1962

By C. M. Frost

The hydrodesulfurization characteristics of a Venezuelan topped crude oil and a Venezuelan reduced crude oil were determined at temperatures from 740° to 850° F, pressures from 800 to 1,600 psig, and space velocities from 1.0 to 2.0 Vo/Vc/hr. Kinetic calculations showed that under these conditions the desulfurization reaction was first order with respect to sulfur and had an average activation energy of 32.5 kcal/mo1. Catalyst life tests made at 750° F, with pressures of 800, 1,200, and 1,600 psig and space velocities of 1.0 and 1.25 Vo/Ve/hr, showed that the decrease in the relative activity of the catalyst was a logarithmic function of time or volume of oil processed and the amount of vanadium deposited on the catalyst. Comparative tests made with residual fuels prepared from a Wilmington, Calif., crude oil and a Wyoming asphaltic crude oil showed that catalyst life may be extended by processing fuel oil with a low metal content, but it may be shortened by the presence of large amounts of asphalt in the feed.

Jan 1, 1971

By Albert E. Long

Diamond-bit performance and cost data accumulated in core-drilling sandstones reveal significant trends of economic interest. Large-size, AA-Grade drill bort suffered less diamond loss per foot drilled than any other size or grade of diamonds assessed. Detailed analyses of the factors that affect diamond-bit performances -diamond size, diamond quality, bit size, bit type, percentage of core recovered, and physical characteristics of bit matrices -are assessed in the tables, graphs, and discussion. INTRODUCTION Since 1945 the Bureau of Mines has been compiling detailed performance records on diamond bits used in core drilling throughout the United States and Alaska. Analytical reports covering bit performance in various rocks are issued as in-formation on a significant number of bits used in anyone type of rock is accumulated. The first three such reports analyzed bit performance in gneiss,2/ schist,3/ and lime-stone and dolomite.4/ This report evaluates diamond-bit performance in sandstone. Data obtained from 627 bits, which drilled 42,665 feet on 45 different projects, are presented. The geographical distribution of the projects is shown in figure 1.

Jan 1, 1958

By Thomas E. Marshall, Anthony T. Iannachione, Leonard J. Prosser

The location and time of 2,007 microseismic emissions from a limestone mine in southwestern Pennsylvania were compared with the development of mine faces and the characteristics of the mine layout. Based on analyses of these results, the occurrence of roof failure zones appears to be associated with certain characteristics of the mine plan. It was determined that significant relationships exist between the intensity of the microseismic activity and the scale of the roof failures Microseismic activity associated with these roof falls occurs In distinct episodes, with the final failure event occurring during approximately a 12-hour period. Each roof fall episode appears to be composed of dozens of distinct roof beam failures. As each beam fails in shear and tension, tens to hundreds of audible noises representing rock fracturing or bedding plane separation can occur. While every roof fell can be viewed as unique, certain mechanistic similarities can be realized through careful observation and monitoring of these complex systems. Understanding these similarities in characteristics allows mine personnel to design the most effective and efficient control technique.

By Stephen C. Tadolini, Thomas M. Barczak

An underground investigation was designed and implemented by the National Institute for Occupational Safety and Health (NIOSH) to evaluate the effectiveness of pre-driven longwall recovery rooms supported with pumpable concrete roof supports. The pumpable roof supports were instrumented with hydraulic pressure cells to measure support loading. Displacement of the support was also measured to assess the support reaction to ground movements. Movement up to 12.5 m (40 ft) into the roof was measured with sonic probes and multipoint extensometers. Borehole pressure cells were installed in the panel fender and outby pillars to evaluate load transfer. Shield loading was also assessed to determine the impact of the panel fender yielding on face loading. The results show that the yielding of the panel fender produced uncontrollable convergence that caused yielding of the shields and stiff pumpable roof supports when the face was approximately 3.12 m (10 ft) from the recovery room. The shields continued to yield until the face advanced into the recovery room. Convergence in the pre-driven recovery room typically reached 15-20 cm (6-8 inches) once the pumpable supports yielded and shed load through a declining residual load capacity prior to being cut out by the longwall shearer. Roof deformations occurred beyond the 10 m (32 ft) horizon with total deformation ranging from five to 10 cm (2 to 4 inches), indicating that standing support was necessary to help control the span as the longwall face advanced into the pre-driven recovery room. Stability improved as the pumpable supports were cut out, thereby reducing the span between the shields and the outby pillars. In the end, the shields were successfully recovered under stable ground conditions. However, a disconcerting discovery was the load shedding of the outby pillars as the recovery room was mined into. This behavior was not expected with a relatively narrow room that is fully supported with standing support. If this mechanism is indeed occurring, the width of the room and performance of the standing support becomes even more critical. Premature failure of the support can lead to excessive convergence on the shield line that cannot be controlled even with modern shields, resulting in instabilities that can lead to catastrophic results. Understanding the load transfer mechanics associated with the advancement of the longwall face into the pre-driven recovery room and the widening of the room to recover the longwall shields is providing valuable information for the refinement of the NIOSH Ground Reaction Curve for standing and intrinsic roof support system design.

By William H. Pomroy, Shail J. Butani

"This Bureau of Mines publication presents a statistical analysis of official U.S. Mine Safety and Health Administration (MSHA) metal and nonmetal mine fire reports from 1950 through 1984, plus accounts of selected nonreportable fires (less than 30 min and no injury) and opinion data on fire hazards from mine safety directors. Fires were analyzed by time trends, ore type, ignition source, burning substance, location in mine, equipment involved, means of detection, duration, number of injuries and fatalities, mining method, and successful extinguishing agent. The leading ignition sources were electricity in underground fires and engine heat in reported surface fires. The most frequent burning substance was combustible liquids for all nonreportable fires, reported surface fires, and reported underground fires from 1978 to 1984. For underground fires reported prior to 1978, timber was the leading burning substance. Mobile equipment was the type most frequently involved in both underground and surface fires. Underground fires occurred most often in haulageway or drift areas, and reported surface fires occurred most often in plant and mill buildings, while most nonreportable surface fires occurred in other areas. The most common methods of extinguishment were water hose lines for reported fires and dry chemical handportable extinguishers for nonreportable fires. INTRODUCTIONIn support of the Bureau of Mines research on mine fire protection, two separate baseline studies on mine fire incidents have been prepared. The first study addressed coal mine fires. The results of that study are summarized in the Bureau's Information Circular 8830, ""A Statistical Analysis of Coal Mine Fire Incidents in the United States From 1950 to 1977."" This second report, addressing metal and nonmetal mine fires, is the companion to IC 8830. Together, these two reports provide a comprehensive, factual summary of the mining industry's fire experience.This report, like IC 8830, covers (1) MSHA fire incident reports, (2) records of nonreportable fires (less than 30 min and no injury), and (3) mine safety directors' opinions on fire hazards. The MSHA fire reports provide the most reliable, objective, and accurate historcial record of the major noncoal mine fires that occurred during the study period (1950 through 1984). However, MSHA fire reports alone understate the true magnitude of the fire problem because metal and nonmetal mines have been legally required to report fires to MSHA only since 1968. Although some fires were reported prior to 1968, doubtless a great many were not. Also, the reporting regulations that took effect in 1968 specify that only fires lasting 30 min or longer or involving an injury need to be reported. MSHA fire reports are thus limited in scope by MSHA's legal authority. In order to provide a more comprehensive data base, it was also necessary to gather and analyze mine company records of nonreportable fires."

Jan 1, 1986

By George D. Dub, FREDERICK G. MOSES

The Bureau of Mines, in connection with the investigations of war minerals it conducted, examined the graphite deposits of this country, studied the methods of mining and preparation used, and sought to devise more efficient methods for the preparation of do- mestic graphite, and to standardize the quality of the product. The graphite investigations covered three general phases, as follows: 1. An examination of the deposits in Alabama and other States, and a survey of the methods of mining and preparation used. In this connection methods of sampling and analysis were noted and ex- periments made to determine a standard method of sampling and a rapid but accurate method of analysis. 2. Experimental work on the concentration and refining of domes- tic crucible graphite to improve the quality of the product and to lessen waste. 3. Experimental work in crucible manufacture to determine the properties of domestic flake and the maximum proportions that might be used without impairing the quality of the crucibles. This work was accompanied by photomicrographic study of crucible structure. In this bulletin are presented the results obtained in the first two phases of the work outlined above. The bulletin is in two parts. The first part describes the methods of mining and milling used, suggests a standard method of sampling finished graphite, and de- scribes a rapid and convenient method of analysis developed at the Pittsburgh station of the Bureau of Mines, to which had been as- signed the analytical and microscopic work. The second part describes experiments on the concentration and milling of graphite, which were made at the Salt Lake City, Utah, station. As soon as the reports incorporated in this bulletin were ready, mimeograph copies were distributed to those persons most interested in order to make the results immediately available. The experimental work on crucible manufacture, assigned to the Columbus, Ohio, station, yielded results which were made known to the industry. Á report on this work will be published later as a separate bulletin.

Jan 1, 1920

By X. Shi, N. S. Dala, V. Vallaythan

"Cellular damage induced by silica dust is known to be associated with increased fragility and destabilization or destruction of the cell membranes. The mechanism by which silica dust effects biological membranes is still unknown. Using the ESR spin-trap methodology, we find that hydroxyl radicals are generated in aqueous suspensions of freshly ground silica. The amount of the radicals generated depends on the extent of grinding and ""freshness"" of the dust. Using linoleic acid as a model lipid, we show that the silica dust causes lipid peroxidation via ·OH, 02-, or linoleic acid related radicals as intermediates. Catalase and superoxide dismutase inhibit the formation of these radicals. The results suggest that free radicals associated with freshly ground silica and the related lipid peroxidation of the memberanes may be the starting point of the silicotic processes.INTRODUCTIONDespite considerable-effort over the years, the mechanism by which the quartz particles exert their toxic action on cells and the process(es) by which these actions progress to fibrosis are still not fully understood (1,2). It is generally thought, nevertheless, that the interaction of the quartz particles with the cell membranes is the starting point of the silicotic process (3). We felt that the mechanism of the membrane damage by quartz might involve oxygenated free radicals because (a) a suspension of quartz particles in contact with alveolar macrophages has been reported.(4,5) to initiate an enhancement of lipid peroxidation, defined broadly as the ;oxidative deterioration of polyunsaturated components of lipids, and (b) hydroxyl (·OH) radicals are known to be capable of peroxidation by abstracting hydrogen atoms from cell-membrane lipids (6) and initiating lipid peroxidation in lysosomal membranes (7). Moreover it is known that exposure of cell membranes, fatty acids and unsaturated food oils to ionizing radiation, which generates ·OH. radicals, causes rapid peroxidation (6). Earlier studies o~ the aqueous chemistry of quartz suspensions have reported detection of HzOz (8), implicating the formation of ·OH radicals as transient species, but, we are not aware of any report of the detection of ·OH radicals in quartz suspensions and this provided the motivation for the present undertaking. Since it is known that, because of their high reactivity (hence short life time) in aqueous media, the ·OH radicals cannot be detected via electron spin resonance (ESR) directly (9,10), we have used ESR combined with the spin-trap methodology (9) for studying the •OH formation."

Jan 1, 1988

By Rudolf E. Greuer, Linneas W. Laage, Xinton Chang

MFIRE is useful for the analysis of ventilation networks under thermal and mechanical influence MFIRE simu¬lates a mine&apos;s ventilation system and its response to altered ventilation parameters, external influences, and internal influences Extensive output enables detailed quantitative analysis of the effects of the proposed alteration on the ventilation system MFIRE was written in FORTRAN 77 and compiled with Microsoft° FORTRAN for the Intel 8086-8088 central processing units The source code is listed in appendix A for users who wish to modify the source code for operation on other computers MFIRE MODIFICATIONS OF MTU-BOM CODE The program described in Bureau of Mines Informa¬tion Circular 8901 has become known as the MTU-BOM codes MFIRE is an evolutionary product of the MTU¬BOM code with major improvements and enhancements 6 For users previously familiar with the MTU-BOM code, the following is a listing of the major improvements and enhancements incorporated by MFIRE 1 The length of an airway is an input value, LA The elevation difference of the airway is calculated from the elevation input, Z, in both programs It is possible for a data file to describe an airway that is shorter than its el¬evation difference The MTU-BOM code does not check for this error and uses the values of LA and Z This does not cause a computational problem, only a simulation problem MFIRE issues a warning message for this case, and the airway length is made equal to the elevation dif¬ference if LA is less than Z 2 To evaluate rock temperatures (average wall surface temperature of airway before a fire), it is assumed that the air temperature at an airway entrance is equal to the air temperature at the airway starting junction, and that the air temperature at the airway exit is equal to the air tem¬perature at the exit junction. The MTU-BOM code follows this assumption in all cases When a rock temperature of less than 0° F is calculated, an average temperature is used to represent the rock temperature of the airway MFIRE uses the same principle, except the consideration of unlikely rock temperatures When the exit junction of an airway is the atmosphere (a fixed condition junction), the air tempera¬ture at the exit is made equal to the air temperature at the airway beginning If an unlikely value of wall temperature (<0° F or > 150° F) results from calculations, a message is issued and the rock temperature is set equal to the air temperature at the airway exit The program user can always input rock temperature (TROCK) for an airway to override the calculated value. 3 MFIRE allows use of an optional reference airflow rate to define and limit the heat generation of a fire source This allows the simulation model to more closely resemble a real fire and to improve simulation conver¬gence Heat generation corresponds, but is not linearly related to airflow rates reaching the fire In the simula¬tion, heat generation is calculated from oxygen consump¬tion and is directly related to the variable incoming airflow Use of this optional reference airflow rate allows the heat generation to vary, but in a damped, user defined manner When the airflow rate passing through a fire source is equal to its reference airflow rate, the data items describ¬ing the fire source are not modified If the airflow rate is lower or higher than its reference airflow rate, the data items used to define the fire source are modified according to the following equations

Jan 1, 1990

By J. W. Paul

This paper deals with the second 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 results public as rapidly as possible. Part 1 dealt with the resistance of unobstructed entries and was issued as Serial 2621 of the Bureau of Mines, in July 1924. Description of tests. After the resistance of an unobstructed entry to flow of air had been determined by tests in the Experiment mine, mine cars were; run into the test section in various arrangements and the increase in resistance was determined. The cars used were of the wooden type with loose end gate, and would hold about one ton of coal, level full. They were 7 feet long. 4 feet 2 inches wide above the wheels, 3 feet high, and had a cross-sectional area of approximately 10 square feet. The average area of the entry was about 57 square feet, the ratio of unobstructed to total area being about 17.6 per cent. The track gage was 42 inches and the wheel-base 20 inches.

Jan 1, 1924

By John Millhiser, Stephen J. Kravits

The U.S. Bureau of Mines preproduction Wireless Survey System (WSS) and its performance during an in-mine test are discussed in this report. The WSS was developed to reduce downhole surveying time in order to increase the efficiency of drilling long horizontal methane drainage boreholes in coal. Borehole survey data are electromagnetically transmitted from the WSS7s downhole guidance probe, via the drill rod, to the uph&apos;ole subsystem in less than 1 min per survey transmission, regardless of borehole depth. The WSS7s in-mine test consisted of providing borehole survey data during the directional drilling of a 2,538-ft horizontal methane drainage borehole in the Pittsburgh Coalbed. By considering available drilling time, which does not include hydraulic drill downtime and the time spent traveling portal to portal, 24 shifts were needed to complete the borehole. Of the available drilling time during the tcst, 50 pct of the time was spent drilling and 50 pct surveying and maintaining the WSS to keep it operational. Previous Bureau experience indicates drilling efficiency was increased 108 pct because of the WSS, in comparison with using a commercially available wire-run directional survey instrument at 10-ft intervals.

Jan 1, 1990

By G. W. Murrie, W. P. Diamond, S. W. Lambert

A geologic study of the Mary Lee Group of coalbeds in the Black Warrior coal basin was undertaken to examine coal stratigraphy and determine regional trends and extent of the coalbeds. The area investigated encompasses 835 square miles in Jefferson, Walker, and Tuscaloosa Counties, Ala. More than 700 core logs were used to construct a structure map, coal, interval, and overburden isopachs, and cross sections. There is evidence that structure affected sedimentation. Coalbed isopachs indicate the Mary Lee Group was deposited in fluvial-deltaic and low-lying coastal plain environments. The Mary Lee coalbed is the only coalbed which is continuous throughout the area, commonly with two benches which have a combined thickness of 2 to 12 feet. The Mary Lee coalbed changes rank in the basin from high- through medium- to low-volatile coal. The methane gas potential of the Mary Lee Group coals is estimated to be greater than 1 trillion cubic feet. There is an excellent correlation between the orientation of surface cleats with those measured underground in the Mary Lee coalbed. The face cleats roughly parallel the axes of the area&apos;s folds and trend northeast-southwest.

Jan 1, 1976

Improve the effectiveness of person-wearable self-contained self rescuer (PWSCSR) training by enhancing the memory retention of trainees in proper donning procedures. Background In the fall of 1989, a total of 185 miners and inspectors were trained by Bureau of Mines personnel to don the SR-100 PWSCSR using the Bureau&apos;s 3+3 method. With the exception of a few individuals, miners were trained underground in an area set up within their working sections. The instructional protocol was as follows: (1) after placing an SR-100 simulator (equipped with a cleaned and disinfected mouthpiece assembly) on the mine floor in front of the worker, a researcher guided him or her step-by-step through the complete donning procedure, (2) the miner was required to perform each step slowly, methodically, and correctly while being talked through the sequence, (3) following this pre-practice instruction, the apparatus was repacked and the subject donned the device without coaching, while being evaluated, (4) if an error was made, the worker received corrective feedback, the unit was repacked, and the entire donning trial was redone. This procedure was repeated until the miner achieved a perfect 3+3 sequence.

Jan 1, 1990

By Edward A. Mihok

Laboratory batch-flow tests conducted on a highly ferruginous acid mine water with an activated carbon showed that ferrous iron is rapidly oxidized. This indicates that air oxidation of ferruginous acid in mine waters is catalyzed by activated carbon. The ferrous iron content of an acid mine water flowing through an aspirated activated carbon column was reduced from about 700 to about 10 parts per million in less than 1 minute. Highly efficient ferrous iron oxidation was achieved by conditioning the activated carbon by repeated treatment with acid mine water and air. The reaction proceeds rapidly in the acid environment (pH about 2.5) engendered by ferrous iron oxidation. The activated carbon was used repeatedly with little loss in efficiency, no discoloration, or solids deposition. In these batch tests, about one-third of the iron was adsorbed by the carbon, but with continuous flow, little iron adsorption is expected. Incorporating a catalytic oxidation step in the treatment of acid mine waters containing ferrous iron would greatly facilitate neutralization--precise control of pH, lower reagent costs, elimination of aeration equipment, and smaller holding ponds.

Jan 1, 1969

By Rudolf E. Greuer, Linneas W. Laage, Xinton Chang

The usual run time errors occur when illegal mathematical operations are attempted by MFIRE For exam¬ple, if the user enters a negative value for the input variable HEAT to model a heat sink or cooling station, a run tame error will occur because an exponential function is employed to better model the changing temperature dis¬tribution in the airways. DATA FILE ERRORS Two types of data file errors can occur. 1 An error may occur because the input data file itself is invalid This may be caused by: The data file cannot be found due to incorrect spelling, drive, or path specification Check the spelling and path at the prompt for location of the data file. The data file contains non-ASCII symbols Check op¬eration of the text processor to insure that only ASCII characters are produced Delete all non-ASCII and/or all out of place characters. 2 Data are accepted by the program, but are incorrect for the data types or ranges or the combination causes a data inconsistency This may be due to. An invalid character is located where a numerical value is required The input data value is outside the reasonable range The input data is insufficient to build the model for simulation. The input data exceeds the capacity of the program. PROGRAM ERROR DETECTION When the program is running, tracing messages are given on the screen indicating the group and lines of data that have been read and the section of the program that is executing Program termination indicates that problems are caused by the subsequent (not read) data file section. For each detected error, descriptive message starting with * ERROR * is issued and the program terminates. When a possibly wrong value and/or its calculated intermediate result is detected, a descriptive message starting with * WARNING * is issued and the program continues. If a modification of input value or calculated intermediate result is automatically made by the program, descrip¬tive message starting with * ATTENTION * is issued and the program continues. LOCATING ERRORS If a message indicates that the error condition occurred due to the data input file, locate and correct the data item. If no error message is issued, but the simulation results are not as expected, carefully check the list of input data shown in the output file WARNING messages and ATTENTION messages may reveal an error in the input data even though the program continues to operate Insure that the default values or modifications adopted by the program run are acceptable. Anomalistic data, though not incorrect or impossible, may lead to an unusual simulation For example, making a fan unusually powerful may prevent a normal strength fire from affecting the airflow distribution in the system Much care must be employed before considering an ex¬treme case. If a message indicates that the accuracy criterion in the temperature section of the program was not satisfied, a table detailing the current parameters of airways which have large fluctuation in the average air temperature from iteration to iteration is produced If the pattern of the parameters is clearly cyclical, while the variation of natural ventilation pressure is stable or cyclical from iteration to iteration, then, most likely there is no single equilibrium stage for the event If the variation of natural ventilation pressure decreases steadily though slowly, increasing the value of data item variables MADJ or ITN (on control line number 1) may allow convergence.

Jan 1, 1990

By R. H. Kudlich

In order to assist the various Federal and State agencies using large quantities of coal to select coal best suited technically and economically to their use, the United States Bureau of Mines has placed at their disposal a fuel inspection service. As part of this service, inspections are made at the mines which propose to furnish coal to these agencies on contracts. Such inspections cover both the mine itself to ascertain its capacity to fur- nish the desired tonnage and quality of the coal, the preparation of the coal in the tipple, and the obtaining of samples for analysis to determine the quality of coal as shipped. To insure that the sample sent to the laboratory for analysis is representative of the average quality of the coal, increments are taken at intervals until a gross sample of about 1,000 pounds of coal has been collected from each of the sizes of coal shipped by the mine, while coal has been coming from all parts of the mine. In reducing this gross sample to the small sample which is sent to the laboratory for analysis it is necessary to crush and quarter the coal by a certain standardized method until only 5 or 6 pounds of coal small enough to pass through a 3/16-inch square-mesh screen remains. The ordinary method which the bureau has followed was to crush the coal by hand with a tamper, such as is used for tamping concrete, on some hare smooth surface and to reduce the volume by quartering and riffling. During the past few years the demands from various Federal and State agencies for this service have been increasing rapidly in respect to bituminous coals. In addition to this, which might be called the normal increase, numerous requests have been received for similar service in respect to anthracite. It was obvious that if this increased demand was to be met it would be necessary either to increase the force allotted to this work or to provide the present force with some means by which their work could be made more effective. A care- ful survey of the situation showed that the greatest amount of time was consumed in trans- porting the men and their equipment from mine to mine in the same district, and in reducing the gross sample to the small finely crushed sample which is to be sent to the laboratory. Both of these phases of the work could be greatly accelerated by providing a motor truck of suitable speed and capacity, carrying a power-operated crusher, and the proper auxiliary equipment to store the gross sample as collected and to reduce it in volume efficiently after it has been crushed. Such a truck has been provided and placed in service. In the eight months it has been in operation the desired results have been fully attained. About twice as many samples as usual have been taken during that time by the same 2-pan crew assigned to this work. Many of the mines in the eastern part of the United States are in hilly or mountainous regions and can be reached only over rough, practically unimproved roads. Hence the speci- fications for the truck were drawn to cover high-quality, long-life trucks, in order that

Nov 1, 1931

This section contains a summary of our investigation of the soil conditions (type, porosity, moisture content, etc.) at the two sites (Lanse and Kato, Pennsylvania) selected for field testing of latex as a soil sealant. Other natural conditions such as rainfall, frostline, depth of the water table, etc., were also measured and recorded for possible later use in assessing the effect of the latex seal on the total environment. The numbered sites referred to throughout this report are shown on the maps of the Lanse and Kato sites (Figures 1 and 2). KA, RB and KC are positions at the Kato site - all other numbered positions refer to the Lanse site. Two other terms used throughout the report which should be explained are “horizon” and "profile". These are synonymous terms for soil layer, A horizon (or A profile) referring to topsoil and B horizon (or B profile) referring to subsoil. The properties that control the flow of water through the soil are of special interest because these will also govern the passage of a sealant into and through the soil. Normally the particle size distribution is a good measure of soil permeability, which is directly proportional to sand content and inversely proportional to silt and/or clay content. Tables I1 and I11 show the percentages of gravel or stones, sand, silt and clay of Lanse and Kato soil samples. According to the United States Department of Agriculture classification, the gravel is ,ignored and the residue separated into sand, silt, and clay fractions. Figures 4 and 5 indicate by means of the USDk soil texture triangle that the variability of composition of Lanse soil ranges from sandy loam in the creekbed to clay loam. The variation is even greater among soil samples from Kato. Porosity of soil, also known as percent voids, is another indication of how readily water will travel through soils. Soil density usually increases and porosity decreases with depth, and as expected, the porosity of the top soil at Kato, a forest, is exceptionally porous and open (see Table IV) The pore diameter and length of soil capillaries is extremely variable, and its distribution in the field is impossible to determine. In addition to the capillaries, soil also contains many macro cracks, crevices, and passages around stones and roots. All these affect the flow rate of water through soil. Poiseuille&apos;s law states that the rate of flow of a liquid through a narrow tube is proportional to the 4th power of the radius of the tube. Pore size normally decreases with depth and in soil containing appreciable amounts of silt and clay this is especially true. Thus, deeper soils should be less permeable and such was the case at Lanse and Kato.

Jan 1, 1972