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By E. W. Dean, W. A. Jacobs

"The petroleum division of the Bureau of Mines in its laboratory investigations, has had occasions to develop a number of types of electrical heating equipment. It was found that electric heaters could be used to particular advantage in the standard distillation test for gasoline. (Dean, E.W., Motor Gasoline, Properties, Laboratory Methods of Testing and Practical Specifications, Bureau of Mines Technical raper 214, 1919, 33 pages.) In order to assist in rendering this type of heater available for general use, a description of the apparatus developed by the Bureau was published. (Dean, E.W., A convenient electric heater for use in the analytical distillation of gasoline,. Jour. Ind, and Eng. Chem., Vol.10, 1918, page 823.) Shortly after the article was printed a chemical supply house undertook the manufacture of an electric heater suitable for gasoline distillation. A preliminary model was examined and tested by the Bureau and modifications were suggested that were incorporated in the type of heater that was finally marketed.Description of the Bureau of Mines-heater: The electric heater developed by the Bureau has an inverted conical resistance Plament surrounded by a layer of heat-insulating material and mounted in a metal case having a top of hard asbestos (Transite) board. The resistance element is a helix of nickel-chromium alloy wire held by a molded core of alundum. The Bureau heaters are generally of about 330 watts capacity and are used with stock types of regulating rheostats capable of reducing the effective wattage to about 43 the full-load maximum."

Jun 1, 1920

By T. Bajpayee, L. Prosser, A. Iannacchione, G. Esterhuizen

Reducing the number of roof fall injuries is a goal of the NIOSH mine safety research program. Central to this effort is the development of assessment techniques to help identify the nature of the risks associated with working under potentially hazardous roof conditions. This paper discusses a method to determine the roof fall risk using a qualitative risk-analysis technique. The ability to determine roof fall risk has been a long-standing goal of safety professionals and could provide the kind of information needed by on-site personnel responsible for worker safety to mitigate roof fall injuries.

By A. J. Farstad, R. G. Olsen

The Coal Mine Health and Safety Act of 1969, passed by Congress in the wake of the disaster at Farmington, West Virginia, led to an extensive study by the National Academy of Engineering of the problems involved in coal mine safety. One of the results of this report and subsequent research conducted by the U. S. Bureau of Mines has been the investigation of electromagnetic techniques for the location of trapped miners after a mine emergency. The Westinghouse Georesearch Laboratory has been involved in both the 2 theoretical and field studies relating to this problem. A compact personal beacon transmitter has been developed which can be attached to and powered by a miner's lamp battery. A compatible lightweight loop antenna package has also been developed which can be easily carried on a miner's belt. This antenna can be quickly deployed on the mine tunnel floor. For the purpose of calculating its electromagnetic fields on the earth's surface, the loop can be considered to be a magnetic dipole buried in the earth. (The earth is assumed to be homogeneous and to have a conductivity of s mhos/m.) The surface of the earth is assumed to be uniformily sloping and the transmitter dipole oriented as in Figure 1. The fields on the earth's surface can be computed by using a superposition of the fields of a 4 vertical magnetic dipole3 and of a horizontal magnetic dipole in proportions which depend on the slope of the terrain. In the case of level terrain a null in the horizontal magnetic 5 field occurs on the surface directly above the dipole. This null is designated as the apparent source location and is the criterion by which the source is located. The criterion was tested at two hardrock mines and two coal mines in the fall of 1972. The apparent source locations were compared to actual locations determined by conventional surveying techniques. It was found that due to nonlevel terrain the apparent and actual source locations differed by up to 13 meters. This discrepancy can be resolved by an examination of the fields of a source beneath uniformly sloping terrain. Figure 2 shows the experimental and theoretical results for a

Jan 1, 1973

By Robert L. Lagace, N. Albert Moussa

The objective of this project was to perform a preliminary study to determine the desirability/practicality of burying the communication cables in underground mines in order to protect then from the effects of fires and explosions We conducted discussions with Government and industry specialists on the physics of mine fires and explosions, mine disaster fighting, rescue, and investigation activities, and on nine operations. In addition we examined published experimental work and selected detailed NSHA accident reports on fires and explosions in underground mines. We found the overall desirability /practicality of cable burial must be regarded at this time as highly questionable, because of its benefit limitations to special sceneries, its practical operational shortcomings, and the availability of alternative cable protection options.

Jan 2, 1982

By Launa G. Mallett, Kathleen Kowalski-Trakofler, Robert H. Peters, Charles PH. D. Vaught, Peter Keating, William J. Wiehagen

On-the-job training is a common means of training or retraining workers and the practice may seem simple and straightforward. Doing it effectively however requires more thought and preparation than simply having someone follow an experienced worker around and watch what they're doing. Over the years, various techniques and practices have evolved that pass on the skills and knowledge of a trainer or coach in a manner that leads an inexperienced trainee to really absorb the information being taught. On-the-job training thus becomes less a haphazard show-and-tell and more a real transfer of information. The goal of this document is to describe how to develop or manage an on-the-job training program so that information is passed on from trainer/coach to trainee efficiently and effectively. By efficient is meant the best use of time and resources of all those involved in the training process, and by effective is meant that the trainee truly learns the skills and internalizes the knowledge needed to perform the job well. The first part of the document discusses topics to think about when developing a formal on- the-job training program. A structure based on coaching is suggested. Then a workshop designed to prepare trainers as coaches is described. Workshop materials include an instructor’s guide and trainee workbook. These materials can be used to train coaches and to assist trainees as they go through the learning process. Content related to specific jobs can be added to these materials to create targeted on-the job-training manuals. Structuring a formal on-the-job training program It is likely that some form of on-the-job training (OJT) is being conducted at your workplace. The formality of that training can range from a structured program to an informal “follow Joe around” method. If your program is completely unstructured, it may not be meeting current training needs. Worse, it may perpetuate bad habits and create “trained” employees who are not given the same information or evaluated to the same standards. Wiehagen et al. comment that, “Success in using unplanned OJT is usually dependent on the luck of the draw, that is, whether the informal trainer is competent at the task he or she is teaching, is motivated to teach, can organize the job into logical components, and knows something about good practices in teaching and evaluating” (2002, p. 27). It is only through planning a structured OJT program that consistency can be created and maintained. At the least, all trainees who have successfully completed such a program can be expected to perform at an established level—they will know what they must do to be successful.

Jan 7, 2005

By W. R. Reed

Dust dispersion modeling is a subject that has had a large amount of research activity. Much of the research has focused on large-scale global or regional dispersion models. Other models have been created for industry-specific purposes. Furthermore, some of the past research has focused on dust dispersion modeling in the mining industry. This report presents the various dust dispersion models that have been developed specifically for the mining industry. The report first gives a brief background of the regulatory environment that helped to promote development of such models. It then presents an overview of the mathematical concepts used in this dispersion modeling. Finally, each of the various models developed for the mining industry are described, along with their associated mathematical algorithms and any field validation conducted on the different models.

Jan 9, 2005

Assure fail-safe stopping of a mining vehicle immediately following a loss of electric power. Approach A separate emergency brake system which actuates when electrical power is interrupted, was installed on several mining vehicles and tested in a long-term underground mining demonstration. How It Works Separate, spring-actuated brakes, which press against brake discs, are used to stop the vehicle following power failure. To allow norm al movement of the vehicle, hydraulic oil under pres? sure from the vehicle's hydraulic system is directed to a spring? loaded piston in each emergency brake housing. That pressure causes the piston to compress the spring and relieves the spring pressure against the puck, thereby allowing the brake disc to turn freely. See Figure 1 A. If the electrical power fails or if the machine is turned off, a valve in the hydraulic line to the emergency brakes opens. That valve, shown as ?Solenoid Valve (automatic)" in Figure 1, which is normally held closed by its electrical solenoid while the vehicle is electrically powered, is opened by the spring in the valve assembly. The pressure in the hydraulic line which is connected to the emergency brakes then drops to

Jan 1, 1978

By Wilbur I. Duvall

In a previous report, entitled A Gage and Recording Equipment for Measuring Dynamic Strain in Rock, a control circuit for a drum camera was described. The purpose of this control circuit was to provide a means for firing seismic caps, synchronizing the firing of the cap with the opening of the camera shutters and generating an electrical impulse at the instant of detonation. The operation of this circuit depended on the following two characteristics of seismic caps: (1) these caps contain a bridge, which breaks at the instant of detonation, and, the firing delay time of the cap is a function of the firing current. During the course of the Bureau's studies, considerable difficulty was experienced from "firing hash", i.e., spurious vibrations that appeared on the records at the time of detonation. The cause of most of this "firing hash" was traced to the intermittent grounding of the cap leads at the time of detonation. As the cap leads were still connected to the firing battery, the grounding of the leads permitted current to flow through the rock to the gage and to return to the firing battery through the shield on the gage cables. The intermittent flow of current along the cable shield produced potentials on the gage leads that were recorded as the "firing hash." To eliminate this difficulty, it is necessary to remove the firing voltage from the cap leads the instant the cap detonates. This report supplements the previous report and describes an improved circuit that can be used to fire seismic caps, remove the firing voltage from the cap leads the instant the cap fires, control the firing delay time in the cap, and generate reference signals at the time current starts flowing in the cap circuit and at the time the cap detonates. These reference signals can be used to determine the firing delay time of seismic caps and the time at which the seismic wave is generated by the explosion.

Jan 1, 1950

By Launa G. Mallett, Charles Vaught

This report is intended to help mine safety trainers better prepare to teach the influx of new underground coal miners who are entering the industry. This is done by identifying two different approaches to instruction and discussing the ways they may affect how well prepared new hires are to deal with a dynamic and hazardous workplace. One approach is based on the use of a syllabus. Those using a syllabus are more likely to rely on lecturing or direct instruction. This is a good way to get across factual information, but does not provide a context within which miners can fit the discrete facts so that they form an integrated whole set of concepts, principles, and skills. The other approach is based on the use of a curriculum. Those using a curriculum may be more likely to help miners integrate concepts and skills that give them an overall picture of the complex mining environment and how they fit into the workplace. This will better prepare them for the decision-making and problem-solving activities that will help them work safely and productively

Jan 1, 2008

By John C. Edwards, Gerald S. Morrow

The U.S. Bureau of Mines has constructed a smoke chamber and developed sensitivity tests for smoke detectors. Response of ionization- and optical-type commercially available smoke detectors have been investigated. Six smoke detectors were measured with respect to visually obscuring smoke characterized by a corresponding optical density for smoldering and flaming coal combustion in the smoke chamber. It was determined that for one type of ionization smoke detector the alarm time was nearly equivalent to that of an odor monitor's alarm for smoldering coal combustion experiments and earlier for flaming coal combustion experiments. The experiments showed that an average CO concentration of 5 ppm corresponded to an optical density of 0.022 m for smoldering and flaming-1coal combustion. Two of the commercially available ionization-type smoke detectors were more responsive to flaming than smoldering coal combustion at an optical density of 0.022 m, whereas the optical smoke detectors-1showed the opposite trend. The responsive characteristics of the detectors evaluated with respect to known smoke conditions in the smoke chamber shows their potential for use as mine fire sensors or part of a mine atmospheric monitoring system to improve mine safety.

Jan 1, 1995

By Horace M. Lawrence, Edmund S. Leaver

"The sulphidizing filming of minerals in oxide ores as a preliminary treatment to aid their recovery by flotation is known practice. In this work the use of barium polysulphide does not appear to have been considered. A study of the properties of barium lead to the following comparative investigation of the sulphides and polysulphides of the alkaline and alkaline-earth metals. It is thought that barium polysulphide may prove to be a more satisfactory sulphidizing reagent than others now in use under conditions that favor the cheaper barium reagent.For the investigation two fairly typical oxidized ores of copper and lead were selected. The copper ore came from the Big Indian Mine in southeastern Utah, and assayed 3.8% Cu; the copper was present in a sandstone gangue mainly as the carbonates, malachite and azurite, with less than 0.2% as sulphides, or silicate. The lead ore is from the Tintic Standard mine in the Tintic district, Utah. It is typical of the oxidized lead-silver ores of that district; the lead is present in an oxidised form in a siliceous gangue, much: Uncolored by ferric oxide. The sample assayed 5.15% Pb and 11.3 oz. Ag.In addition to the results obtained in this investigation, there are included some results secured by Mr. J. B. Lain, consulting metallurgist of Reno, Nevada, on a sample of ore from the Chino Copper Co. The ore assayed about 1.7% Cu, of which about 0.25% was nonsuiphide."

Aug 1, 1925

By R. W. Crocker, H. H. Clark

The purpose of the investigation discussed in this bulletin, one of a series dealing with the use of electricity in mines, was to study the various means and methods used to confine the flashes that occur when a switch carrying electric current is opened. The flash result- ing from the opening of a 250-volt direct-current circuit carrying more than half an ampere will ignite explosive mixtures of mine gas and air. An equally dangerous flash may be produced by even less cur- rent from a 500-volt circuit. Few mine electric circuits carry less than half an ampere when in use. The need of protecting the switches of such circuits in places where gas is likely to be present is therefore obvious. Two general methods have been proposed for preventing switching flashes from igniting gas surrounding the switch. One method is to inclose the switch in a casing provided with openings that are covered with wire gauze or otherwise designed and equipped for preventing the passage of flames from the interior to the exterior of the switch casing. Switches so protected are called explosion-proof switches. The second method is to immerse the switch contacts in oil to a depth sufficient to quench any flash that may occur when the switch is operated. Switches so protected are called oil switches. The success of the first method of protection depends upon the proper design and construction of the switch casing. It is essential to the successful operation of the second method that the switch contacts be surrounded by the proper kind of oil in good condition. There are several ways in which an oil switch may be deprived of its protective feature. The oil tank may not be filled or, if filled, the oil may leak out or be spilled. The oil tank may be removed (in some designs) and not replaced or through neglect the condition of the oil may become such that it is no longer an efficient protection. While such contingencies are not likely to occur, and although oil switches may be so designed that the loss of oil is not probable, nevertheless, as compared with oil switches, explosion-proof switches seem to

Jan 1, 1913

By A. B. Hooker

Investigations at the Pittsburgh Experiment Station have shown that the satisfactory operation of aflame safety lamp depends not only upon proper design and assembly of the lamp but upon the kind of fuel used, and that much of the trouble experienced with permissible flame safety lamps at mines is due to the common use of motor gasolines, none of which is suitable in the present types of permissible flame safety laps. This report gives the results of a limited study to determine what satisfactory fuels are available, the specification limits of such fuels, and to suggest modifications of assembly and care of the lamps to improve performance with any satisfactory fuel.

Jan 1, 1938

By John Gross

In connection with some investigations being made at '!'he Ra.re uid Precious 1ets.ls Station of the U, S. Bu.rea.u of Mines, at Reno, Nev., on the precipitation of gol'i and silver from cyanide solutions, it wa.s sug­ gested tnat the use of acetylene for this purpose be investigated, A pa.tent was iss·.ied to Fre<!.erick W. Martin and Frederick Stl1.bbs in 1900 covering the precipitation of precious metals from cyanide solu­tions by acetylene, The acetylene used in the tests described below wa3 made f'rom a. corr.:nercial cal ci \'!Z:l carbid.e, A r..umber of exper:me11. +,s rezul ted in more or lP.ss ccmplete pree;p1tatien of silver, -but 1n no case was a11Y gold precipitated. As silver acetylide, obtained by precipitatir.g the silver from an ar:::ncni'i\.Ca.l so1ut1on of silver n,. tra.te by acetylene, is yellowish white, esn:, solu'.)le in cyanide and hlghly explosive, and the pr9cip1tate ob­tain£ frcvm the cy'31lide sclutions was black, not tlubla L., cyanide and not explooive, it 'Na.s deid-,d. to ir.·.restigate the na.tur.e of the slJ.ver pre­cipit.te !rem the cy;r:iide solu·t:i.i,ns, !n prepa;.•i::lg a lge (!\,wrttity ,:f the preci-pi tte 1 t. wa, fo·und that a.fter c,:.\i;:1 ete prEc"'.pi tat ion cf the eil ver the !IOl ution con ta.ined soluble eulphic.e • Thia p:!:'O'lided a el f!W "lt·d. a.ft er apr,ropri-9.te tests the preeipita.te VIO,I proved to 'be ailver sulphide.

Apr 1, 1922

Dec 1, 2007

By L. J. Prosser, A. T. Iannacchione

From 1991 through 1995, 44 miners out of a total workforce of less than 2,000 were fatally injured in the stone industry. Of these, 12 occurred at underground mining operations with nine deaths resulting from roof or rib falls. A safer environment can be achieved by evaluating the nature of the hazardous ground and by developing more efficient and effective ground-control strategies Roof and rib conditions were observed and assessed in 33 underground stone mines in Illinois, Indiana, Kentucky, Maryland, Missouri, Pennsylvania and West Virginia (Fig. 1). Hazard assessment indicated that the ground failures that occurred under moderate to substantial overburden. i.e., >30 at (100 ft), were caused by stress concentrations and geologic strictures. Ground failures near the surface are caused by solution (water) processes. Selection of the mining horizon and mine-layout decisions tremendously influence ground stability.

By F. S. Crawford

This report deals with the effectiveness and economy of installing mine timbers treated with preservatives in long-life service locations. Early in the present century, when mine timbers and labor were plentiful, it was not general practice to install treated timbers in such places. Because national sources of good mine timber are declining steadily, the mining industry must now conserve timber. Moreover, the cost of installing and replacing mine timbers has been rising. Therefore, even the simplest of treatments can be expected to give some return on the investment when applied to timbers that are to be installed in relatively permanent locations. Better methods of treatment will produce better returns. In a service test of maple timbers treated by the hot-and cold-bath method and installed in main haulageways of the Athens mine of the Cleveland Cliffs Iron Co., Negaunee, Mich., zinc chloride-treated timbers had an average useful life of 13.3 years; borax-treated timbers, 11.2 years; and sodium fluoride-treated timbers, 7.7 years. Untreated timbers used as controls had an average useful life of 3.8 years.

Jan 1, 1950

By Stephen C. Tadolini, Thomas M. Barczak

Roof support systems, longwall shields in particular, have persistently grown in size and capacity for the past 25 years. Why is this? Is it a good thing or is it unnecessary? What are the consequences of this “bigger-the-better” design philosophy? Rarely do we see a “one size fits all” approach to roof support except when it comes to longwall shields, where the historical trend for new procurements is to simply purchase the highest capacity support you can buy. Does high capacity ensure failures will not occur? The answer is no! The highest capacity tailgate supports are typically the ones that fail the most often. What does this tell us? It tells us that there are fundamental aspects of support design and ground control that we still do not understand or recognize when designing a support system. This paper provides an interesting evaluation of these issues and proposes a different approach to support design that attempts to match the support performance characteristics to the ground behavior. Along the way, some of the old premises of support design will be discarded, and new “controversial” ideas developed. Thinking outside the box never hurt any industry. Mining has made it a common practice.

By D. S. Colby

The productive capacity of natural gasoline and cycling plants in the United States or. January 1, 1954, was 926 thousand barrels per day, according to the Bureau of Mines biennial survey. This represented an increase of 114 thousand barrels per day during the 2-year period since the last survey. In the previous 2-year period, capacity had increased 164 thousand barrels per day. The total number of plants increased from 521 on January 1, 1952, to 535 on January 1, 1954. The number of operating plants increased from 506 to 521. The major increases in capacity took place in Texas, Illinois, Oklahoma, Louisiana, and New Mexico, with the absorption-type plant continuing to account for most of the new construction. In 1954, however, 6 plants reported using a refrigeration process whereas only 1 plant reported this in 1952. The number of operating compression-type plants continued to decline and combination plants showed a decline this year because a number of these plants were reclassified as absorption-type.

Jan 1, 1954

By Paul T. Allsman

SCIENTIFIC inquiries concerning phenomena that may influence mining technology were widely publicized during the year. The deep-hole drilling project "Moho," 3 the use of nuclear explosives underground, and the recovery of minerals from the depths of the sea became subjects of scientific and general discussion. The mining industry continued to watch these developments with keen interest: but its more immediate concern was the increasing tempo of competition between mineral commodities, the domestic producers of these commodities, and foreign sources of supply. The competitive situation has intensified the industry&apos;s efforts to develop more efficient new mining methods, as well as to improve the efficiency of present practices. The attitude of the industry was well illustrated by rapidly expended use of low-cost ammonium nitrate explosives, the establishment of rigid schedules for equipment maintenance, and close attention to the detailed costs of production. The complexity of planning a new coal mine is aptly illustrated by the editors of Mechanization in the April 1959 Issue, in which they outline the cost of developing a mine and the various problems, factors, and decisions involved.4

Jan 1, 1960