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By David C. Oyler, Gregory Hasenfus, Gregory M. Molinda

Few studies have specifically measured and documented the large-scale loading behavior and durability of ventilation stoppings to mining induced movements, particularly from longwalls. Ventilation stoppings are more commonly the concern of ventilation engineers, and ventilation stopping response to ground movement has only been documented in an incidental manner. This paper presents the investigations of underground measurements that have been conducted to determine the loading response of stoppings constructed from lightweight aggregate concrete masonry units (CMU). These investigations have produced some interesting results that may prove beneficial, not only for developing and assessing alternative stopping construction techniques, but also for designing and selecting standard construction methods for use in varying mining conditions. For instance, the interface friction that results from wedging a CMU stopping during construction plays a substantial role in its ability to resist both lateral and vertical loads. Although they are not intended for ground support, the study showed that block stoppings can resist vertical loads of at least 2,700 to 3,000 kN. Asymmetric loading of a stopping may result in localized failure of blocks within a stopping, which, depending on the severity, can be a precursor of impending stopping failure. In addition to measurement results and implications, the paper will also present details of field measurement methods used to assess stopping response. Stopping stiffness and material strength characteristics will also be presented.

By Kenneth O. Bennington

This investigation is part of the Bureau of Mines research effort directed at advancing mineral technology and minimizing energy requirements for extractive metallurgy. The emplacement of the primary minerals petalite (LiAlSi4010) and spodumene (LiAlSi206) in the lithium pegmatites is examined on the basis of their Gibbs energies of formation determined from lithium metastltcate and oxides, using a series of proposed reactions. The reaction between spodumene, quartz, and petalite (LiAlSi206 + 25i02 [=] LiAlSi4010) apparently does not take place in nature but may be proved experimentally.

Jan 1, 1982

By D. J. MacDonald

The Bureau of Mines has carried out investigations on a method for producing zirconyl sulfate solution from zircon sand, comprising (1) reacting zircon sand with molten NaOH, (2) leaching the resultant fusion frit with water to remove sodium silicate and to convert sodium zircon-ate to hydrous zirconium oxide, and (3) leaching the hydrous zirconium oxide from unreacted sand with hot, dilute H2S04 to produce crude zirconyl sulfate solution. The following conditions were found to be suitable: reacting 0.6 kg of NaOH per kilogram of zircon sand for 10 min at 600° C; leaching the frit with 3 to 4 liters of water per kilogram of solids; leaching the residue with 5.1 liters of water and 1.25 liters of 98-pct H2S04 per kilogram of original solids for 10 min at 90° C; and filtering or decanting to recover unreacted zircon sand. A preliminary cost estimate is included.

Jan 1, 1982

By C. D. McMaster, John C. Hartley

Three systems that monitor ventilating fans are described . These electronic monitoring systems automatically perform most of the operations required to conform with the provisions of the Federal Mine Safety Code in the event of fan failure or slowdown .

Jan 1, 1964

By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

9. Remote Sealing System Sensitivity 9. 1 Introduction In the previous sections a description of the overall system has been presented along with detailed descriptions of the equipment and techniques employed with the preliminary probing system, the seal em¬placement system and the seal checking system. In addition, the use of these subsystems in a specific mine application has been described in considerable detail. A broad range of parameters of interest was specified in the contract, as summarized in Section 1. 3. Most of these are a function of the general location; i. e. , the location of the mine, and the specific location; i. e. , the location of the boreholes. These parameters of interest include passage size, shape, depth, slope and water con¬ditions. The length, diameter and location of the boreholes within the mine passage and on the surface are critical parameters as well. A few additional parameters may affect one or more of the remote sealing subsystems. These include temperature, topography, rock and soil conditions, and underground water. While variation in these parameters will not render the system inoperative, consideration of them in the planning stages will simplify and expedite the field operation. In the following sections the effect of the various parameters on the remote sealing operation will be discussed. For clarity, the several tasks, borehole drilling and casing, preliminary probing, fly ash delivery, foam topping and seal checking, will each be considered separately.

Jan 1, 1973

"""Hazard"" is the general expression used by safety engineers to denote risk, or the danger to property or human beings from the contingencies peculiar to different industries. Where a business, family, or individual is subjected to possible financial loss from any particular hazard, it is customary and is considered good practice to insure for reimbursement of possible loss. Accordingly, we take out insurance for earthquakes, for fire, for accidents, etc., and are charged a different premium for each. The premium rate is based on our relative exposure to the hazard in comparison to the total loss to our particular class of business in our geographical location over a given period.Insurance, then, must be considered as the experience of a group rather than of an individual, and any individual may be fortunate or unfortunate over stated periods. Through the law of averages, the probability of loss because of exposure to hazard is becoming more accurately measured as experience is accumulated and data are analyzed.Lion human life came to have a financial value in the eyes of the law, and employers were held liable for losses through accidents to employees while on duty, insurance companies began to underwrite the accident risks of the different employers and divided them into classes based on the amount of risk involved. Premiums for compensation insurance are based on relative exposure, which is measured by pay roll. The premium is rated in proportion to the severity of losses established by statistical studies.' It soon became evident that the accident experience of employers in the some industry varied widely; that is, there were good and bad risked in the same line of business. This resulted in ""experience rating"" of premiums, meaning thereby that an employer with experience in accident cost was premium rated in proportion to his losses over a stated period (usually three or more years)."

Feb 1, 1926

By Wilbur I. Duvall

The Bureau of Mines presents a theoretical solution for the stresses and displacements in an infinite elastic plate containing a circular hole whose boundary is subjected to applied shear loads over four separated arcs. The results for the applied shear loads can be superimposed on the results for applied radial loads, given in a previous publication, to obtain a complete two-dimensional approximation of the stresses and displacements induced in the rock by tunnel boring machines anchored in a circular tunnel by means of four props. Analysis of the various solutions shows that the tangential tensile stresses induced on the boundary of the circular tunnel by applied radial loads can be minimized in the roof and floor of the tunnel by the application of appropriate shear loads to each of the four props. Thus when planning tunnel boring operations, consideration should be given to the in situ stress field in the rock and the induced stresses in the rock resulting from the applied radial and shear loads produced by the props of the boring machine.

Jan 1, 1968

By Forrest T. Moyer

Injury experience in the mineral mining and processing industries during 1968 was slightly improved in the nonfatal-injury record but worse in the fatality record. The resulting frequency rate of all injuries was slightly better, whereas the injury-severity rate retrogressed appreciably from the figure for 1967. Overall operating activity, as measured by man-hours of worktime, was slightly higher in 1968. However, there were several major segments of the mineral industries in which activity was lower owing to reduced demand for mineral products and to several major work stoppages. These statistics comprise the injury and work experience of all personnel engaged in production, exploration, development, maintenance, repair, and force-account construction work, including supervisory and technical personnel, and working partners and owners at mineral-producing and mineral-processing establishments in the United States. Data concerning officeworkers are excluded except for the oil and gas industry for which such information is not separable. All injury rates and totals are calculated from data before rounding. The data for 1968 are preliminary except for the anthracite, coke, petroleum and natural gas, native asphalt, peat, and slag industries, which are final. The figures represent full coverage for all industries except oil and gas for which coverage is not complete, particularly with respect to small companies.

Jan 1, 1970

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' 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***,'" The natural conclusion to be drawn from such records is that lack' 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 '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 Joseph Cervik, Gerald L. Finfinger

The Bureau of Mines conducted an experimental degasification project in Island Creek Coal Co.'s Virginia Pocahontas No. 5 mine. Methane from the over- lying Pocahontas No. 4 coalbed was entering mine workings in the Pocahontas No. 3 coalbed through fractures in the roof rock. Small-diameter (1-5/8-inch) holes were drilled into the overlying coalbed to reduce the gas pressure and intercept methane flows, which were piped to the surface through an under- ground 6-inch-diam steel pipeline. The total methane flow rate from the vertical holes averaged 150,000 ft3/day for the first month. Methane flows into the mine were reduced by 47 pct, thereby demonstrating the effectiveness of this form of degasification in reducing ventilation requirements and providing a safer working environment.

Jan 1, 1979

By R. E. Head, Virgil Miller

"INTRODUCTIONRecent investigations at the Intermountain Experiment Station of the Bureau of Mines at Salt Lake City indicate that metallurgists have given little attention to the occurrence of jarosite minerals in the oxidized ores of lead and silver. These investigations have also emphasized the importance of knowing when these minerals occur in the oxidized ores, especially those containing lead, silver, and gold, as their presence is a material factor in selecting a suitable kind of treatment. Since the question of the occurrence of jarosites in oxidized ores has come to the attention of the Bureau of Mines, investigation has indicated that plumbojarosite and argentojarosite are quite common. These two minerals appear to be widely distributed and probably escaped recognition by persons who had attempted to treat certain oxidized lead ores in which the jarosite minerals represented a material portion of the metal content.Consideration of the physical characteristics of the jarosites also indicates that in many cases failure to treat some of the oxidized lead ores with success has been directly due to the fact that the greater portion of their lead and silver content was present as plumbojarosite and argentojarosite. The data and the description of these minerals given in the body of this paper indi¬cate that attempts to recover lead and silver from ores in which appreciable amounts of the metals occur as plumbojarosite and argentojaeosite would be unsuccessful if confined to gravity methods of concentration. There are un-doubtedly considerable tonnages of oxidized lead ores in the various mining regions of this and other countries, and it is quite probable that in some of these ores the metal content of lead and silver may be largely anglesite (lead sulphate) and cerussite (lead carbonate) but that they will also contain cerargyrite (silver chloride), argentojarosite, and plumbojarosite. The treatment of such ores therefore presents an important problem, since a product is discarded from ores from which the recoveries of lead and silver have been below 70 per cent which is probably too low-grade to warrant aftertreatment by any process now in use."

Apr 1, 1928

By Maurice Deul, Herbert H. Fields, John H. Perry

The Bureau of Mines has been promoting health and safety in mining since its establishment in 1910. One area of research covers methane control in coalbeds; this report describes a multipurpose borehole used for both degasification and the production of commercial-quality gas. The multipurpose borehole was drilled into a barrier pillar, and seven horizontal degasification holes and one pressure point hole were drilled radially out from its perimeter. On January 28, 1974, after 505 days of degasification, a compressor was installed to the exhaust stack of the multipurpose borehole (2), and pipeline--quality gas was introduced into a commercial pipeline. As of February 4, 1975, over 171 million cubic feet of gas had been purchased by the gas company. The in situ pressure at a depth of 200 feet into the coalbed and the average gas flow and water flow from the degasification holes as they were completed and closed off were 203 psig, 1,200,000 cfd, and 6.8 gpm, respectively. Twenty-four hours after the seven holes were connected through individual pipes to the atmosphere, the total gas and water flows and the in situ pressure dropped, respectively, to 971,000 cfd, 1.3 gpm, and 18 psig. Five hundred days later, the corresponding values were 620,000 cfd, 0.15 gpm, and 10.5 psig. Daily flows have been as high as 800,000 cfd, and as low as 360,000 cfd, during the last 500 days. On February 4, 1975, after 882 days of degasification, 576 million cubic feet of gas had been removed from the Pittsburgh coalbed; apparently a much larger area of virgin coal is being degasified than is defined by the holes. This study indicates that horizontal boreholes drilled into a coalbed from the bottom of any shaft will effectively remove gas from the Pittsburgh coalbed.

Jan 1, 1975

By G. G. Morgis, J. J. Forbes

"INTRODUCTION The greatly diversified and increased uses of beryllium and its con& pounds in recent years have focused attention on the health hazards incident thereto. The Bureau of Mines has a fundamental interest in safety and the elimination or reduction of health hazards in the mineral and allied industries, and it recognizes that serious hazards are inherent in the production and use of beryllium and its compounds. This circular presents a review of the literature pertaining to such health hazards but does not describe original research by Bureau personnel. Most of the bibliography has boon either quoted in part or abstracted in an effort to present information in a comprehensive and readable form.In reviewing the literature, differences of opinions wore recognized in the writings of the respective authors, but no attempt was made to evaluate such differences. This presentation was devoted strictly to reporting without editorial comment.SUMMARYAlthough beryllium was known to industry for about 150 years, its toxicity did not present any serious problems in the United States until the advent of World War II, when the increased use of this element and its compounds brought to light several toxicologic reactions occurring primarily in the lungs and skin of workers handling it. The pulmonary effects, characterized as acute pnoumonitis and chronic pulmonary granulomatosis in beryllium workers, are far more serious than the dermatological manifestations.The addition of beryllium to the list of toxic industrial metals has boon so recent that there is still some confusion in the clinical picture. Data on magnitudes of exposure likely to be responsible for the production of disease are not yet adequate. There appears to be no relation between the severity of exposure and the development of cases some of those having had severe exposure have not developed a reaction, whereas those having a slight exposure in some instances have developed a response."

Jul 1, 1950

By Robert A. Bruce

A motion transducer based on coherent mixing of laser light backscattered from rough surfaces is evaluated in terms of sensitivity, bandwidth and range. Tests made with a prototype composed of a 4-mw HeNe laser, a silicon avalanche photodiode, and a 15-cm aperture telescope demonstrate that remote measurements with reasonable bandwidth and accuracy are feasible at distances up to 100 meters.

Jan 1, 1977

Provide minx operators with means for evaluating dust generation and bit wear effects on Production without costly and extensive underground testing. Approach Develop personal-computer-based cutting system models that will simultaneously evaluate machine, Coal seam, and mine-operator-controlled parameters for their interactive effects on dust generation, bit wear, and Production by either a longwall shearer or a continuous miner. How It Works CSM Programs have been developed to analyze relative dust generated by a double-drum, ranging arm, longwall shearer and a continuous miner. These interactive programs Provide relative dust, culling forces, and production values for any given set of mining machine parameters, specific seam conditions, and operator-controllable parameters. Expanded versions of each program provide a dynamic evaluation of the effects of bit wear, over time, on production.

Jan 1, 1989

By William L. Rice

Geochemical humus sampling techniques were used by the Bureau of Mines in investigating a potential large, low-grade gold deposit in the Orogrande district, Idaho. Conifer needle humus samples were processed by ashing and fire assay-atomic absorption analysis. An area bearing anomalous concentra¬tions of gold and silver was outlined by the geochemical method.

Jan 1, 1970

By Pablo Velasco

Ecuador had limited mineral output, al-though the Government attempted to stimulate metallic mineral exploration and also evaluated a gypsum and a phosphate deposit. A pilot plant to exploit gold deposits was established, and there was extensive gold exploration activity in southern Ecuador. Domestic output of iron and steel declined sharply. Among all minerals, petroleum output was the dominant factor with both exports and production increasing significantly over that of 1988. Crude oil exports contributed 63% of total export earnings and about 70% of the central Government's revenue.

Jan 1, 1986

Improve the safety of mine workers by developing a means of forecasting impending roof falls in underground mines. Approach The Bureau of Mines, through in-house and contract research, has developed the Roof Fall Warning Device. This battery-operated, portable electronic system forecasts roof falls by detecting and interpreting high-frequency rock noise, The technology has shown potential for detecting stress-related failures in a variety of underground environments. How It Works All geologic materials produce high-frequency acoustic emissions when they encounter an increase in stress. These ultrasonic frequency range events ( >20kHz) are well above the audible range of human hearing, very small in amplitude and duration, and can only be detected with sophisticated electronic equipment.

Jan 1, 1990

By Howard F. Puariea

This paper is one of a series describing methods and costs of recovering sand and gravel from alluvial deposits in the United States and deals directly with the methods employed by the Portland Gravel Co. in operating a clamshell dredge on the Willamette River near Portland, Oreg., and a pump dredge on the Columbia River near Vancouver, Wash. These papers are designed to disseminate technical information regarding the methods used. The cost tabulations represent local expenditures only and not total production costs. It is recognized that publication of total costs may in some instances cause embarrassment to individual producers as well as to the industry as a whole. On the other hand operating costs are essential to the technical discussion and study of methods employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulations shall ensue.

Jan 1, 1932

By R. Barany

This paper reports determinations of heats of formation (from the oxides and elements) of crystalline cadmium metasilicate and crystalline lead meta-silicate by hydrofluoric acid solution calorimetry. The results, in conjunction with known entropy values, yield free energies of formation. There are no earlier data of this type for cadmium metasilicate. The results of this investigation for lead metasilicate deviate from the literature values (which are less reliable) in the direction of increased thermodynamic stability. Both cadmium and lead metasilicate are much less thermodynamically stable with respect to their constituent oxides than are the corresponding compounds of the alkaline earth metals.

Jan 1, 1959