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By John A. Organiscak

Laboratory and underground studies were conducted by the Bureau of Mines to evaluate the effectiveness of a water-powered scrubber and a brattice partition to create a clean split of air for longwall workers at the tailgate. In simulated laboratory tests, the system was very effective in creating a clean split of air. Observed system efficiencies were 74 and 84 pct with induced airflows of approximately 2,000 and 2,500 cfm, respectively. Underground evaluations indicated that the system was capable of reducing respirable dust at the tailgate. The first underground evaluation resulted in protection efficiencies of 30.7 and 42.5 pct at scrubber water pressures of 150 and 450 psig, respectively. A 33.7-pct protection efficiency was observed in the second underground evaluation with a modified partition and the scrubber operating at 250-psig water pressure. To be most effective, the system should have the scrubber operating at a flowrate of 10 gpm at 500 psig to deliver a maximum quantity of cleaned air behind a well-sealed partition.

Jan 1, 1983

By Roy H. Grau

The National Institute for Occupational Safety and Health (NIOSH) has conducted research to improve the ventilation of large-opening mines whose entries are at least 93m2 (1,000 ft2). The ventilation of large-opening mines is unique compared to other types of mines because (1) it is challenging to keep airflow velocities high enough to effectively remove or dilute airborne contaminants because the entries are so large, (2) large air volumes can be moved through the mines with little static pressure drop, and (3) stoppings that are used to direct ventilation airflows are costly to construct and to maintain. The research results suggest that the ventilation of large-opening mines is improved significantly by incorporating ventilation planning into the mine planning process, using propeller fans to direct airflow, developing new stopping materials and construction methods, and using long pillars to eliminate crosscuts where possible.

Jan 1, 2009

By John C. Edwards

Carbon monoxide (CO) sensors are used in mine fire early-warning systems. Experiments were conducted by the U.S. Bureau of Mines with six diffusion-type CO sensors to determine their response to a reference CO concentration under both static and dynamic flow conditions. Static experiments were conducted with 0.5 L/min flow of 16 ppm CO in N2 through 8-and 12-L chambers. Dynamic flow experiments were conducted in two environmental chambers: One had directional flow capability of 1 m/s, and the second provided moderately nondirectional flow as high as 1.8 m/s. Reference CO concentrations of 13.5 to 19 ppm in air were used for the dynamic experiments. The results of the static experiments demonstrated that the sensors consistently underestimated the reference gas concentration. The dynamic experiment results showed the sensors provided reasonable agreement with the reference gas concentration when directional flow effects were not considered. Directional flow effects were evaluated for two sensors. One of the sensors showed a strong dependence upon the relative orientation of the diffusion tube with respect to flow direction. The second sensor did not show a dependence upon flow direction. The sensors' directional flow effect is significant for their proper in-mine utilization.

Jan 1, 2010

By Je M. Oh

The Bureau of Mines is conducting research to determine the high temperature oxidation resistance of substitute stainless steels (SS) containing two less strategic elements, Al and Si, instead of Cr. Chromium is considered to be a critical and strategic metal. Although the Cr content was reduced to 8 wt pct, the alloys showed better oxidation resistance than did 304 SS containing 18 wt pct Cr. Specifically, the alloys that contained Fe-8Cr-16Ni with combinations of Al and Si showed excellent oxidation resistance even at temperatures up to 1,000° C. In this study, the effects of the alloying elements on oxidation kinetics and morphology of oxides were investigated using a Cahn Rg electrobalance, scanning electron microscopy, an energy-dispersive X-ray analyzer, X-ray diffraction, and an electron microprobe. Aluminum and silicon additions in combinatin were more effective in providing oxidation resistance than either element was alone.

Jan 1, 1986

By A. B. Hooker

Since man first mined underground, there has been need for adequate illumination; this need has never been fully supplied. At first, suitable lamps were not available. Gradually they have been developed, but along with that development the need for better and better lamps has continued owing to the following conditions and factors: 1. Increasing hazards from gas and dust ignitions. 2. The speeding of operations with mechanized mining, which necessitates greater visibility. 3. A demand that cleaner coal be loaded, which requires higher levels of illumination. 4. The cost of compensation for injuries that has created a demand for better illumination and safer lamps. Use of better lamps has been retarded by: 1. Prejudice and resistance to change on the part of the workers in some districts. 2. The cost and upkeep of the lamps. 3. The present types of lamps, while a great improvement over the old lamps, do not entirely fulfill the requirements for a safe and efficient light for underground workers.

Jan 1, 1938

By W. R. Wrzensinski

This report presents the findings from a l-yr Bureau of Mines program in which sulfur concrete reinforcing materials were tested and evaluated to determine their resistance to corrosion. It also summarizes the permeation characteristics of sulfur concrete and the exemplary performance of precast, reinforced sulfur concrete structures in various industrial environments. The Bureau is furthering the development of sulfur concrete technology as part of a larger effort to find uses for the Nation's plentiful sulfur resources in construction materials. Sulfur concrete is a corrosion-resistant material that can be used in acid and salt environ-ments where conventional materials fail. Penetration of corrosion-inducing agents is minimized because of the low permeation characteristics of sulfur concrete.

Jan 1, 1988

By Michael A. Trevits

The National Institute for Occupational Safety and Health (NIOSH) in partnership with Strata Products tested the sealing capability of Ventstop®? as part of an ongoing mine fire control and suppression research program. Ventstop®? is a multi-purpose, inflatable device that is produced by Minvent Solutions and is available world wide for use in the metal and nonmetal mining industry. Ventstop®? is also used in the Australian coal industry as a temporary ventilation control device. The device can be quickly deployed, is reusable and can be placed in horizontal and vertical mine voids to control dust, fumes and smoke. Deployment, multi-day inflation and air leakage tests were conducted at the NIOSH Lake Lynn Laboratory to determine the capability and limitations of Ventstop®? in a simulated coal mine setting. During the tests, Ventstop®? was also subjected to low level forces of a nearby methane gas ignition. It is thought that Ventstop®? could be used by the US coal mining industry to temporarily close an underground mine area in response to a fire or spontaneous combustion heating event, to temporarily redirect mine ventilation during longwall equipment moves or during stopping construction. This paper describes this inflatable temporary mine sealing technology and presents the results of the NIOSH tests. Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of NIOSH.

Jan 1, 2009

By P. A. Surgeon, R. R. Sayers

It is not the purpose of this report to try to describe all the work done during the past year for the improvement of health or the prevention of illness among miners , but to call attention to a few of the more outstanding investigations in which progress has been made . Among these , the investigations on the physiological effects of carbon monoxide , dust and ventilation , and temperature and humidity will be discussed . Carbon Monoxide . During the years 1920 and 1921 , much more work has been done on the various A survey phases of carbon monoxide than has been carried on for a number of years . of carbon monoxide poisoning in the American steel works , metal mines , and coal He conmines was made by Dr. Henry S. Forbes , of the Harvard Medical School . ** cludes from his survey that late after- symptoms following acute severe gassing rarely occur , and that almost always there is evidence of pre - existing pathological conditions when such effects do appear . He further states that he found no evidence of cumulative harmful effects resulting from frequent exposure . Dr. Forbes , Dr. Forbes , assisted by Louise Hompe , made a laboratory investigation in which anesthetized animals were exposed to carbon monoxide , illuminating gas , and benzol *** . The investigators conclude that , under the conditions of their experiments , there is no change in the coagulation time of the blood . It has been stated by many investigators that the blood of those affected by carbon monoxide does not clot as quickly as normal blood . While the investigation referred to above may not cover all the conditions , it is a valuable contribution to the subject as it indicates that the small hemorrhages found in the membranes covering the central nervous system , abdominal organs , etc. , at autopsy of those dying of carbon monoxide poisoning is probably not due to direct toxic action of the gas upon the blood .

Feb 1, 1922

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

Volumetric measures [ ]

Jan 1, 1962

By M. Kanda, J. W. Adams

A system for measuring amplitude probability distributions (APD’s) of electromagnetic noise in coal mines is described and typical APD’s from an underground coal mine are presented. The APD is a basic statistic required for the design and analysis of communication systems, especially those intended for use in noisy environments, and where neither overdesign nor underdesign is acceptable. The rms and average field strengths are obtained by integration of the APD, and examples are shown at several frequencies. All field strength levels are given in absolute units. Selected frequencies cover the range from 10 kHz to 32 MHz.

Jan 1, 1973

By T. O. Llewellyn

The Bureau of Mines investigated the use of a heavy liquid in combination with fluid cyclones to separate brucite from a Nevada ore on a continuous basis, using a mixture of dibromomethane and trichloroethylene having a density of 2.44 grams per cubic centimeter. Single-stage cyclone separation produced a concentrate that contained 84 percent of the total magnesia at a grade, on a calcined basis, of 95.6 percent MgO.

Jan 1, 1974

Illinois has the largest reported bituminous coal resources of any state and is one of largest coal-producing states in the nation. Coal-bearing rocks underlie about 65 percent of Illinois, including all or part of 86 of its 102 counties. An estimated 18 1 billion tons of coal resources are still in the ground. Using present mining methods, more than 30 billion tons of coal are classified as recoverable. This represents almost one-eighth of the total recoverable reserves of all types of coal in the United States. The state's surface mining regulatory program was conditionally approved June 1,1982. It received full approval October 25,1988. The Abandoned Mine Land Program was approved June 1, 1982, and the AML emergency authority June 11, 1984.

Jan 1, 1992

By M. J. Friedel, D. F. Scott, T. J. Williams

In an effort aimed at monitoring mining-induced stress changes that may influence ground failure, the US Bureau of Mines conducted a series of active 3-D seismic tomographic surveys at the Homestake (Lead, South Dakota) and Lucky Friday (Mullan, Idaho) mines. Existing rock bolts were used to mount geophones and as strike points for introducing seismic energy using a 3.6 kg sledge hammer. Travel time measurements were recorded spanning up to 160 m between drifts at several levels. The tomographic uncertainty was minimized by computing iso-velocity surfaces of constant probability based on statistics from multiple reconstructions and a threshold criteria. Periodic imaging using tomographic velocity surfaces demonstrated that temporal and spatial changes in the local stress field occurred in response to ground failure and stope advancement at a gold and silver mine, respectively. Keywords: Temporal imaging; Mine-induced stress; Seismic tomography; Geophysics

Sep 9, 1996

By D. A. Paice, A. B. Shimp

A test program was conducted to determine the adequacy of molded case circuit breakers for dc electrical systems in coal mines. Mine electrical system parameters and the most severe operating conditions to be expected were determined. Tests of the interrupting capabilities of several molded case breakers were made under the worst conditions to be expected. Continuous and pulsed current carrying capability of the breakers was also investigated. Breakers from two different manufacturers passed all tests successfully. Based on the results of these tests, a set of guidelines for applying molded case breakers to dc systems has been prepared.

Jan 1, 1975

By Ralph L. Rinehart, Wils L. Cooley

This paper summarizes recent experiments with grounding systems. Problems and potential hazards related to in-mine grounding systems are discussed. The monitoring of trailing cable ground conductors and testing of commercially available ground monitors are discussed.

Jan 1, 1975

By William H. Schiffbauer, William D. Mayercheck, August J. Kwitowski

This report summarizes work sponsored by the Bureau of Mines in the development of a remote operating system (ROS) for controllng a thin-seam continuous miner (TSCM) 500 feet or more distant from the extraction face. Detail s are provided on ROS subsystems including the continuous miner, video equipment, controls and displays, the electronic control system, and the operator station.

By James P. Rider, Jay F. Colinet

The National Institute for Occupational Safety and Health (NIOSH) has conducted benchmarking surveys at longwall operations across the country to identify current operating practices and the types of controls being used. Gravimetric and instantaneous dust sampling was completed to quantify dust generation from major sources and determine the relative effectiveness of the different control technologies. Results from the underground dust surveys will be presented as an update on longwall dust control technology and operating practices.

By D. Dolinar, T. P. Mucho

Horizontal stresses are caused by global plate-tectonic forces. During 1995 alone they were largely responsible for the closing of two longwall mines in the United States. This paper presents six case histories from Pennsylvania, West Virginia, Kentucky and Alabama. In each case, a mine encountered roof falls or difficult ground conditions at the headgate caused by horizontal-stress concentrations. The problems are detailed, and the control measures adopted are described. In most cases, nearby longwall panels without stress concentrations were trouble free. The paper also discusses detailed measurements that were made at two adjacent Pennsylvania longwalls. One headgate was oriented to avoid a horizontal-stress concentration, and the other was not. Eliminating the stress concentration dramatically reduced roof support loads and roof deformation. The paper concludes that proper panel orientation and sequence is the key to maintaining headgate ground control. The optimum orientation is not parallel to the maximum horizontal stress, as previously thought, but rather it is 20° in the stress shadow of the gob. Other stress-control techniques, including artificial support, are briefly discussed.

Lower noise exposure levels for operators and cleanup personnel working in portable nonmetallic mineral crushing and screening plants.

Jan 1, 1983