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By E. P. Youngman

The law of June 5, 1911, suplements and amends the Laws of April 21, 1810 (the basic law) and May 2, 1837. The Royal Decree of September 15, 1919, coordinates the provisions of the Law of June 5, 1911, with those of the Laws of April 21, 1810, of May 2, 1837, and of July 8, 1865, that have remained in force, as well as with certain articles of the Law of September 1, 1913, which revisad the system of taxation. The revised code has been brought together in one volume.3 All citations in this abstract refer to the coordinating Royal Decree of September 15, 1919, unless it is otherwise specifically indicated.

May 1, 1930

By B. R. Mohal, F. F. Aplan, S. Chander

"Dust abatement by water sprays involves the subprocesses of 1) collision between dust particles and water droplets, 2) adhesion of particles to droplets, and 3) engulfment of particles by the droplets. A review of the fundamental aspects of these subprocesses shows that collisions between particles and droplets are determined by aerodynamics and the size and surface charge of the particles and of the droplets. However, the adhesion and engulfment subprocesses depend upon the wetting characteristics of the particles. Although wetting agents (also known as surfactants) have been used as dust suppressants in several investigations, conflicting results are available regarding their effectiveness. In this paper, we show that these results can be explained if the effects of coal rank on surfactant adsorption and wetting characteristics are taken into account.The influence of several nonionic surfactants containing polyethoxy adducts on the wetting behavior of coal is presented. The wetting was determined by a modified Walker Test method, and contact angle measurements. The results show that the wettability of coal depends upon coal rank, structure of the hydrocarbon chain of the surfactant, and the number of ethoxy groups in the molecule.IntroductionDue to the inherent nature of the mining process, a large number of particles are generated, a portion of which becomes airborne to create dust. Dust can be aesthetically and environmentally unacceptable and it can also be explosive. Fine particles in the respirable size range ( < 5 urn) are con-sidered to cause lung diseases, namely, silicosis, pneumoconiosis, etc.(1) Several approaches to reduce dust in mine environments are practiced throughout the mining industry. These include decrease in generation of dust through improvements in mine machinery, ventilation (in which lower dust levels are achieved by dilution of contaminated air with clean air), and dust removal methods. Water sprays are most commonly used to remove dust par-ticles. Recently, scrubbers are reported to have been installed on mining machines to remove dust,(2,3) which also make use of water sprays to reduce dust."

Mar 1, 1989

By L. C. IlsLey

From time to time the Bureau of Mines has issued publications dealing with the various classes of explosion-proof mining machinery that have been tested and approved as permissible for use in mines having atmospheres that may become inflammable by reason of the inadvertent presence of gas or dust. These publications are confined almost entirely to description of the features contributing directly or indirectly to the prevention of explosion or shock hazards, and are intended to give inspectors, safety engineers, and others already familiar with the general safety requirements more detailed information on the safety features of the design of a particular machine. As a background for papers describing permissible machines and to avoid the necessity of duplicating descriptions of methods of conducting investigations and tests of such machinery, Bureau of Mines Bulletin 305, Inspection and Testing of Mine-Type Electrical Equipment for Permissibility, was pub¬lished in 1929. Three bulletins giving detailed descriptions of the three most numerous types of machines have been issued, viz., Bulletin 313, Permissible Storage-Battery Locomotive and Power Trucks. Bulletin 343, Permissible Coal-Handling Equipment. Bulletin 392, Permissible Coal-Cutting Equipment.

Jan 1, 1937

By R. Karl Zipf, Z. T. Bieniawski

"SummaryAs part of an effort.to understand the mechanics of fine fragment formation in coal, which is important in studies of respirable dust due to mining, fracture toughness measurements and the strain energy density (SEO) theory were applied to calculate the crush zone size under a cutting tool in coal. This · zone is the major source of fine fragments in the 1 to 10 µm size range. The model used in these calculations is a boundary element program containing a failure criterion based on the SEO theory. The boundary element program calculates linear elastic stresses at numerous points in the coal material ahead of a cutting bit. These stresses arc then input to a subroutine called critical ftaw length and orientation (CFLO) which uses the SED theory to determine the CFLO for a small crack at the boundary element stress computation point. The extent of crushing is based on earlier postulates about . the role of inherent flaws in a fragmentation process. To form 1 to 10 µm fragments requires firstly a local stress strong enough to activate flaws with a characteristic length less than 1 to 10 µm and secondly, a flaw density sufficient to provide an average spacing between flaws also on the order of 1 to 10 µm. The locus of active lO µm ftaws represents the maximum possible extent of fine fragmentation in the 10 µm or less size range assuming that a sufficient inherent flaw density exists. The approach offers a first order approximation to the extent of crushing under a tool tip. The size and shape of the crush zone volume is affected by the attack angle and geometry of the tool.IntroductionFine fragment generation in the 1 to 10 µm size range under the action of a generic coal cutting tool may be explained on the basis of fracture mechanics which suggests two major sources of fine fragments: first in a crush zone near the tool tip and second by shear fracturing. along major macrocrack surfaces (Zipf and Bieniawski, 1988a). In this paper, fracture toughness measurements and the strain energy density theory are used to calculate the crush zone size. This zone represents the major source of fine fragments in the 1 to 10 µm size range and understanding the mechanical factors controlling its size represents a first step toward using fracture mechanics to characterize the ·tendency of various coals to produce undesirable fine fragments."

Aug 31, 1989

By Wilder D. Foster

In estimating the hazardous qualities of a dusty atmosphere it is frequently desirable to determine the composition of the air-borne dust. Samples collected from ledges or from the rock itself are Likely to be unsatisfactory for this purpose owing to the possibilities of differential disintegration of the rock and of variations in settling rates of the different components of the minerals. It may be necessary, therefore, to collect samples of dust from the air. Samples collected from the air may be analyzed chemically, by X-ray diffraction, and by the petrographic microscope. Chemical methods are unsatisfactory owing to the small samples usually available and to the limitations and complexities of: present methods. X-ray technique requires expensive apparatus not ordinarily available except in research laboratories. Owing to the simplicity and rapidity of petrographic is examination of atmospheric mineral dusts, it was considered worthy of further study.

Jan 1, 1938

By K. D. Luxbacher

Understanding methane emissions in underground coal mines is critical for a safe and productive mine. In addition to reasonable estimation of initial coalbed reservoir parameters, it is also crucial that changes in effective stress due to mining and pore pressure reduction are taken into account due to their effects on porosity and permeability. Primary parameters for estimation of emissions or modeling of the mining environment for this purpose are porosity and permeability which can change dramatically as a result of stress redistribution associated with mining and gas desorption from a large coal volume. These parameters affect the emission rates and ventilation requirements, as well as water inflow into the working environment. Stopping leakage, on the other hand, is a secondary stress dependent factor in estimation of emissions, as convergence of the roof and floor strata, compromising the integrity of the stopping, may result in leakage, making prediction of ventilation requirements difficult. This paper aims to examine the effects of porosity and permeability changes of the coal seam on methane emissions in an underground continuous miner section. The models were developed and executed in a dynamic fashion to simulate an advancing section. Through this process, the changes of effective stress in coal, particularly their change paths, on porosity and permeability were incorporated into the models and methane emissions, concentrations, air requirements, water inflow and possible leakage from the stoppings were investigated using a conventional coalbed methane reservoir model.

Jan 1, 2009

Reduce dust exposure of longwall shearer operators by keeping them upwind of the primary cutting drum. Approach Use a different coal cutting sequence by cutting from headgate-to-tailgate, making the cleanup pass from tail-gate-to-headgate. How It Works The cutting action of the shearer drum is usually the primary source of respirable dust at longwall shearer faces. Dust exposure of the shearer operator is deter-mined by his position relative to the lead drum, which is normally in the raised position taking a full sump. On long-wall faces where the cut pass is taken from tail-to-head, against the primary airflow, the shearer operators must remain at their controls, on the return-air-side of the primary dust source, to maintain proper control. A simple method to lower shearer operators&apos; dust exposures is to extract the primary coal from head-to-tail, thus positioning the operators up-wind of the lead cutting drum. The bottom coal is then cut, and the floor cleaned by the trailing drum during the tail-to-head cleanup pass. This sequence places the primary dust source, the cutting action of the shearer drums, on the return-air side of both shearer operators, except when cutting out at the longwall headgate.

Jan 1, 1984

By D. J. Bauer

A pure scandium solution was concentrated from 10-4 mole per liter to 0.5 mole per liter by continuous foam fractionation in a spaced, packed column. Recovery in the foam was 77 percent using a spaced, packed draining column with sodium n-methyl-n-"coconut oil acid" taurate as the surfactant. The technique was first studied batchwise in a small unpacked column to determine the more important variables. Optimum surfactant concentration was found to depend on scandium concentration. Extraction and, in general, enrichment ratios were highest in the 2.5 to 3.5 pH range at temperatures ranging from 50° to 70° C. An airflow rate of 136 ml./min. was satisfactory in the equipment used.

Jan 1, 1962

By BUREAU OF MINES

LIST OF PUBLICATIONS ON CERAMIC INVESTIGATIONS U.S. BUREAT OF MINES .

Jan 1, 1923

By L. C. IlsLey

From time to time the Bureau of Mines has issued publications dealing with the various classes of explosion-proof mining machinery that have been tested and approved as permissible for use in mines having atmospheres that may become inflammable by reason of the inadvertent presence of gas or dust. These publications are confined almost entirely to description of the features contributing directly or indirectly to the prevention of explosion or shock hazards, and are intended to give inspectors, safety engineers, and others already familiar with the general safety requirements more detailed information on the safety features of the design of a particular machine. As a background for papers describing permissible machines and to avoid the necessity of duplicating descriptions of methods of conducting investigations and tests of such machinery, Bureau of Mines Bulletin 305, Inspection and Testing of Mine-Type Electrical Equipment for Permissibility, was published in 1929. Three bulletins giving detailed descriptions of the three most numerous types of machines have been issued, viz., Bulletin 313, Permissible Storage-Battery Locomotive and power Trucks. Bulletin 343, Permissible Coal-Handling Equipment. Bulletin 382, Permissible Coal-Cutting Equipment.

Jan 1, 1937

By Frank E. Cash

Large quantities of explosives are consumed in the underground mining of ores in the Lake Superior district. Because of the recognized danger of accidentally releasing the potential highly destructive forces contained, the safes possible procedure in the transportation, storage, and use of explosives is necessary. Underground magazines recently constructed in the district give evidence of the earnest desire of the mine operators to incorporate all possible safe-guards in the storage of explosives, including a careful choice of location and arrangement in the plan of the magazine.

Jan 1, 1946

Reduce exposure of longwall face workers to respirable dust generated during the advancement of roof supports. Approach Identify and implement current water-application and improved support-movement practices used to lower support-generated dust. Defining the Problem Bureau studies have shown that on some longwall faces support dust can contribute over 30 percent of the respirable dust exposure of face workers. Conditions contributing to high levels of respirable dust generation during support movement are: depth of cover greater than 1,000 ft; immediate roof consisting of coal top or friable shales; and face-air velocities in excess of 500 fpm. Moreover, at most longwalls, supports are advanced on the intake-air side of the shearer as it travels with the airflow. This places the shearer operators, and in many cases the support movers, downwind of support advance, thus increasing their respirable dust exposures.

Jan 1, 1984

By Byron. O. Pickard

"An Arizona mining company recently demonstrated a new use for the geophone by successfully locating leaks in compressed-air lines which were buried under from 1-1/2 to 2-1/2 feet of fine rock fill. The following information is abstracted from data sent to the Bureau of Mines by the superintendent of the mine.The company has two parallel main compressed-air lines, about one and one-half miles long, buried under an average of two feet of fine rock fill. One of the lines is a four-inch high-pressure (1000 pounds) main, and the other line a ten-inch low pressure (90 pounds) main. The two mains are separated by a 10 to 3C foot interval, and run from the compressor plant to the No. 2 shaft, where they are taken underground. A pump line is also buried in the immediate vicinity.Several leaks, not audible enough to be located, were developed in the Alms. Various =Abode were suggested that did not seem practicable to the management. Finally, the company obtained a Bureau of Mines' geophone and experimented with it. The first test& were conducted while the pumps were running, and while there was noise on the concrete pavement, all of Which caused so much vibration in the geophone that it was impossible to detect the leaks.The second attempt was made at the close of the day shift when the compressors were not operating and when the pumps could be shut down. The valves in the far end of the surface lines were closed, and the lines were pumped to full pressure (90 and 1,000 pounds respectively).Geophone readings were then taken at 7 or 8 foot intervals directly see the lines. Several leaks some very large in the high-pressure line were audible with the geophone at distances varying from 15 to 30 feet. A con-le leak in the low-pressure line was found at a distance of 10 feet. detecting the leaks, no difficulty was found in locating them exactly. ""At this time"", laid the superintendent of the mine, are unable to large a leak must be in order to be located under two feet of loose geophone. The fill we worked over was quite loose and dry and unfavorable for the work in question. However, we have no that the instrument is a valuable adjunct to our business""."

Aug 1, 1922

By Jeffery L. Kohler, Eric R. Bauer

Prolonged exposure to noise over a period of years generally causes permanent damage to the auditory nerve and/or its sensory components. This irreversible damage, known as noise-induced hearing loss (NIHL), is the most common occupational disease in the United States today. Workers suffering from NIHL have difficulty understanding human speech and hearing other workplace cues. Despite the use of regulations and efforts by government and industry to reduce NIHL, the problem today is as prevalent as it was more - than two decades ago. Recently, the Mine Safety and Health Administration (MSHA) promulgated a new regulation that is designed to reduce NIHL in the mining industry. One of the more significant provisions is the elimination of MSHA&apos;s past practice of giving "credit" for the use of personal hearing protection, thereby reestablishing the primacy of engineering and administrative controls. However, there is a knowledge gap that is impeding the development and implementation of engineering and administrative controls. Although significant data exist on the exposure to noise by occupational code, little is known about the noise sources that contribute the most to the worker&apos;s dose. This is problematic in a workplace with multiple noise sources and workers who travel among noise sources. Yet without this knowledge, it is difficult to focus control efforts in any practical manner. Thus, it is important to characterize noise sources sufficiently well so that the sources most hazardous to hearing are identified and those conditions of exposure that are most amenable to engineering controls are pinpointed as well. The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) is conducting a cross-sectional survey of noise sources and worker noise exposures in the mining industry to address this deficiency. The initial effort, conducted at a coal preparation plant and results are described in this paper. Preliminary analyses indicate that the noise levels on all floors exceeds 90 dBA in most areas, and that levels as high as 115 dBA were recorded. In addition, the one worker whose responsibility is to monitor the equipment and "house clean" the plant is slightly overexposed, even though he spends only half the shift in the plant. General information on the hearing loss problem in mining, a review of hearing protection use and noise regulations in mining, and other background materials are also presented.

By E. D. Gardner

Humphreys Gold Corporation of Denver, Colo., was conducting a successful placer operation in 1936 on North Clear Creek about 6 miles below Blackhawk in Gilpin County, Colo. About 3,000 cubic yards of gold-bearing gravel are dug daily (September. 1936) by two draglines and a power shovel. The gravel is screened in a portable washing plant; the trommel oversize is discarded, and the undersize is pumped to a gold-saving plant. The gold is caught in riffles in sluice boxes. The total cost of mining is about 20 cents per cubic yard. The mine is in a narrow canyon at an altitude of 7,200 feet. The Blackhawk-Central City branch of the Colorado & Southern RR. runs over the property. Freight platforms for receiving supplies were moved as the workings advanced. The workmen reached the mine on a speeder that ran on the railroad tracks from a point on the automobile highway (U. S. 40) on Clear Creek near the bottom of Floyd Hill, about 5 miles distant. The mine is 36 miles by road and speeder, or 30 miles by rail, from Denver.

Jan 1, 1937

By Mark I. Copeland

The formation of A1203 dispersoids 0,14 and less in size in dilute iron-aluminum alloys by internal oxidation in wet hydrogen and dispersion strengthening of iron by application of the technique to iron powder were found to be feasible by the Bureau of Mines. In flowing H2-1.5 H20 gas, A1203 dispersoids 0.1w and less in size formed (at 650° to 750° C) in Fe-l and 2 Al sheet material but not in Fe-3 or 4 Al alloys. With higher temperatures and/or higher H2O/H2 volume-ratio gases, A1203 and FeA1204 dispersoids >0.14 in size formed in all the sheet materials- Minus 100-mesh Fe 2 Al powders were internally oxidized under conditions that promoted formation of fine A1203 particles in sheet material, and then the oxidized powders were hydrogen reduced, sintered, extruded, and evaluated. During internal oxidation, fine A1203 dispersoids formed within the powder grains, and coarse FeA1204 particles formed on the powder surfaces and grain boundaries. The FeA1204 content was essentially eliminated during sintering by reacting with the unoxidized aluminum that remained in the center of the larger internally oxidized powders. The tensile strength at 800° C depended upon the aluminum-oxygen weight ratio of these elements in the extrusions and reached a maximum of 17,000 psi. The stress-rupture strengths at 800° C of the better alloys were comparable with those of type 310 stainless steel.

Jan 1, 1972

By E. J. Gleim

Contact with trolley wire in the mines of the United States has taken a considerable toll of life throughout the years that trolley locomotives have been employed as a means of&apos; transportation. A study3/ of the records over a 15-year period for one State alone showed that, of 98 fatalities resulting from contacts with electrical circuits and equipment, 75 were caused by direct or indirect contact with unguarded trolley wire in coal mines. The law relating to guarding trolley wires in the mines of this particular State, as amended in 1935, reads in part as follows: "All trolley wires carrying 220 volts or more, and less than six feet six inches above top of rail, must be guarded at all points under which men and animals are required to pass***,&apos;" The natural conclusion to be drawn from such records is that lack&apos; of guards or shields must be held responsible for these fatalities. As a preventive measure, it has been advocated that every foot of trolley wire in mines should be guarded. Although some such drastic steps may appear to be amply justified, closer examination of the records nor this and other coal-mining States shows that absence of guards is not entirely responsible; but rather that other factors, such as carelessness and neglect it the observance of certain well-established simple rules concerning installation and location of trolley wires, also are responsible. In other words, if trolley wire is installed carelessly and its maintenance is neglected, it should not be expected that the mere installation of guards will overcome such carelessness and neglect. This publication discusses Various types of guards that have been used in Coal and metal mines of this country, together with related steps bearing upon the problem of &apos;preventing shock and fatalities from contacts with trolley wire. The material herein contained is taken largely from Information Circular 6577,4/ now out of print, and has been revised to include some types of guards that have been used in metal mines, together with a discussion of guard materials not covered in that publication.

Jan 1, 1945

By R. V. Ramani, C. B. Manula, A. Owili-Eger

Network analysis of mine ventilation systems is not new, having been traced back to 1854. A Committee Report (1970) has also reported the extensive work done in this respect in the United Kingdom, Japan, U.S.S.R., South Africa, United States, and other countries. Wang, et al (1970) developed a computer program which is an improvement over the earlier one developed by Wang et al (1967). The program has been recently modified and extended to include methane emission features by Owili-Eger (1973). This computer program incorporates all the novel features of the earlier programs. These include the capabilities of mesh selection, free splitting, internal or external fans, natural ventilation pressure and fixed quantity branches. The program is written in Fortran IV and, in effect, is an experimental mine in which many ideas can be tried out. The computer produces, besides the input data and certain computational data, the quantities and head losses in the branches, the head losses to be adjusted in the fixed quantity branches and the fan operating point. The last named program, hereafter to be referred to as the PSU/MVS, is presented in Appendix I. The application of this program is demonstrated in this manual through a series of selected examples. Application of the methane generator program is not included here as a detailed report on the subject is available elsewhere (Ramani et al, 1975).

Jan 1, 1975

By S. E. Khalafalla

The ability of potentiometric, gas-sensing electrodes to reliably monitor free gaseous molecules in solution has been recently demonstrated. A gas such as sulfur dioxide from a dilute sample solution diffuses through a hydrophobic, gas-permeable membrane to an internal filling solution. The latter solution contains a sufficiently large excess of sodium bisulfite, the concentration of which can be considered constant regardless of the quantity of sulfur dioxide entering by diffusion. The electrode response is essentially due to the liberated hydrogen ions from the bisulfite-sulfur dioxide equilibrium. This Bureau of Mines report describes a new technique used to detect the formation, and to estimate the stability constant, of gas-molecule and gas-ion complexes in solution, as part of an effort to minimize the undesirable environmental impacts associated with mining and mineral processing. Although the unknown activity coefficients of the neutral and ionic species in the external solution complicate the quantitation of results, methods to circumvent these difficulties are presented. The technique is based on the isometric shift of the Nernst diagram of ion-selective electrodes to higher concentrations relative to the standard aqueous calibration curve. The method is applied to detect and estimate the formation constant of a sulfitocitrate complex, and agrees well with an independently determined stability constant of the disulfitomercu-rate complex.

Jan 1, 1978

By C. E. Hennig

On January 1, 1960 there were 310 petroleum refineries in the United States, with a crude-oil capacity of 9,901,424 barrels daily, according to the Bureau of Mines&apos; annual survey. Compared with a year ago, this represents a net decrease of three in the number of refineries and an increase of 81,578, barrels per day in crude-oil throughput capacity. Continuing the trend to fewer units with greater individual throughput, the capacity of the average refinery in the United states increased during 1959 from 31,373 barrels per day to 31,740 barrels per day. Compared with the previous year, total crude-oil capacity of refineries on January 1, 1960 was lower in the Appalachian No. 1, Other Rocky Mountain, and Texas Gulf refinery districts. All other districts showed slight increases in capacity. At the beginning of 1960 the industry had under construction facilities that would increase the crude-oil capacity in the United States by 70,947 barrels per day. This was the smallest capacity increase under construction at the beginning of the year since 19460 Included in this construction of additional capacity were two new refineries, one in Michigan and another in Hawaii. In addition, the industry was constructing facilities to replace 50,250 barrels per day of existing crude-oil capacity.

Jan 1, 1960