Search Documents

By S. H. Katz, J. J. Bloomfield

In studies of mine and tunnel ventilation conducted by engineers of the Bureau of Mines , various smokes are used to determine flow of air , direction of the currents , and the rate of mixing . The instrument for generating streams of sulphur trioxide (SO ) smoke , shown in the drawing herewith, has been found helpful , convenient and practicable for such purposes ; it is also especially useful in some places where fire for generating smokes is not permissible . The apparatus consists simply of a glass tube containing fuming sulphuric acid on granular pumice stone , attached to a rubber syringe bulb . When a squeeze of the bulb blows air through the tube , a stream of dense white smoke evolves, which follows and makes visible the air currents . The tubes after preparation are hermetically sealed to prevent deterioration . When ready for use , they are easily broken open at a file scratch for the purpose on both tips , and inserted into a rubber nipple at the bulb . Sometimes it is of advantage to attach them to a longer rubber tube leading to the bulb . Tubes of the size shown (about 1/2 inch outside diameter by 5 inches long) are usually sufficient for the needs of a day . Thereafter they cease to fume because the acid absorbs moisture from the air and looses its effectiveness . Smaller sizes of tubes and larger have been made , but the size shown has proved most practicable . Immediately after a person has finished using a tube it should be buried or disposed of in a place where it will not be touched by shoes or clothing, or come in contact with wooden floors , furniture , or metals , because the acid , which will eventually leak from the tubes , is highly corrosive . -- Reports of Investigations , Department of the Interior , Bureau of Mines .

Jul 1, 1923

To provide for continuous remote sensing of carbon monoxide (CO) in underground mines. The Approach A transducer module has been developed as a wall-mounted, continuously operating instrument that will measure ambient levels of CO, and produce a signal that is proportional to the concentration.

Jan 1, 1982

By J. M. Stuve

A novel calorimetric solution technique, recently developed at the Bureau of Mines, was tested using synthetic samples of chalcocite (CU2S) and covellite (CuS). The solution of these refractory sulfides was accomplished by oxidation with bromine in a moderately acidic, aqueous solution. The resulting values for the standard enthalpies of formation (?Hf°, 298.15) for CU2S(c) and CuS(c) were -18.1 ±1.1 kcal/mol and -13.3 ±1.1 kcal/mol, respectively. These values are in good agreement with published formation values derived from other methods of physicochemical measurement.

Jan 1, 1982

By Rimas Pakalnis, Ted Williams, Tom Brady, Wilson Blake, Mary MacLaughlin, Kathryn Clapp, Cristian Caceres, Mario Morin

This paper describes a focus of work presently being conducted at the Rock Mechanics Research Group at the University of British Columbia. The underhand method under consolidated fill ensures a high recovery under an engineered back that is comprised of cemented rock fill and/or cemented paste fill. This method of mining is generally necessary either due to a weak rock mass comprising the immediate back and/or high induced back stresses. A major concern in the design of sill mats is the loading and strengths associated with the overlying sill mat. This paper reviews past practice coupled with present observations and measurements from over ten (10) mines throughout North America. It outlines areas of concern in terms of design requirements.

By G. R. Friggens

A nuclear method for continuously monitoring the coalbed and ash levels and void formation in commercial-scale, fixed-bed, pressurized gas producers is proposed. Measurement of gamma ray transmission through the coalbed is the basis of the method. The coalbed level is monitored by detecting the trans-mission of gamma rays from a 1 to 2 Ci Co-60 source positioned on the outside wall of the vessel. Coal bridging or, alternatively, ash level is monitored by a 10 Ci Co-60 source at the center of the coalbed. Source activities and geometries are calculated for a 12-foot-ID producer designed to operate at 350 psi. Source capsule and detector specifications and operational safety are also discussed.

Jan 1, 1973

By Raymond L. Carpenter

In connection with its continuing studies of the characteristics of alloys and alloying elements, the Bureau of Mines investigated the crystal structure of fused boron. This report describes how the structure of fused boron was found to be rhombohedral by the powder method for crystal-structure determinations by X-ray diffraction. The determinations of the crystal structure of boron reported in the literature were made on crystals prepared by various methods such as electrolysis, thermal decomposition of a boride, or by hydrogen reduction of boron tribromide. Table 1 summarizes the data found in the literature on the crystal structure of boron. The information shows the following: (1) Three structures have been reported for boron, (2) boron prepared by different processes--or even by varied conditions of a process--produces crystals of different structure, and (3) no information is given on the crystal structure of fused boron.

Jan 1, 1960

Compare the fire endurance of paneled steel stoppings with that of traditional concrete block Stoppings. Background Permanent stoppings or partitions arc used in mines to separate ventilation airways. The ability of stoppings to retain their structural integrity for a minimum length of time under lire conditions and prevent the spread of flame and toxic combustion products to an adjacent airway is critical. The success of miners in reaching safety during a fire depends largely on the presence of uncontaminated airways. Traditionally, permanent stoppings for coal mines are constructed of concrete blocks. Recently, paneled steel stoppings that satisfy many of the requirements demanded of permanent stoppings, such as incombustibility and strength, have been introduced. Their use also introduced concerns such as the ability of a steel stopping to maintain its ventilation control function when exposed to a fire and the potential that the fire could transmit enough heat through the stopping to ignite combustible materials on the unexposed side. To address these concerns, the Bureau of Mines investigated the fire endurance of galvanized steel and concrete block stoppings.

Jan 1, 1989

By W. F. Marshall

The effect of engine parameters on exhaust emissions from two diesel engines was studied experimentally. Fuel-injection characteristics and intake air conditions were considered as parameters influencing the emissions. Emphasis was placed on the effect of parameter variations on nitrogen oxide (NOx) emissions, because diesels generally emit very low levels of carbon monoxide (CO) and unburned hydrocarbons. Emissions other than NOx were at lowest levels when the engines were adjusted for best performance. NOx emissions can be diminished somewhat through variation in fuel-injection characteristics, but there generally are penalties in emissions of CO, smoke, and unburned hydrocarbons or in engine performance. Temperature and composition of intake air have a significant effect on NOx emissions. Levels of NOx are reduced by recirculating the exhaust gas or by adding water to the intake air stream. However, the rate of water added or exhaust gas recirculated must be limited to prevent the degradation of engine performance and increased emissions of CO and smoke. At high exhaust recirculation rates, levels of CO and smoke were increased such that it was necessary to derate the engine and also to use a catalytic system for oxidation of CO.

Jan 1, 1971

Continuous remote sensing of air speed In underground mine airways. Approach An ultrasonic technique measures a form of air turbulence which is proportional to air velocity. How It Works The stainless-steel enclosed transducer consists of a sensing head with circuitry, and a telemetry card. The sensor uses a patented ultrasonic technique to measure a form of turbulence created In the air. This turbulence, known as vortex shedding, is related to the air speed through the sensor. Air flowing past a cylindrical post creates vortices which flow down the air stream on both sides of the post. Pulses from an ultrasonic transmitter pass through the vortices to a receiver; the effect of the vortices on the pulses is a measure of air velocity. The transducer contains a telemetry card, known as an accessor, which transmits reports on air velocity through a pair of wires to a monitoring system. The accessor contains an analog-to-digital converter and digital telemetry circuitry required for computer system operation. The transducer does not contain any read-outs or alarms and air velocities are displayed by means of a centrally located

Jan 1, 1982

Provide a coalbed methane data source for industry use in mine planning. Approach Coalbed methane data have keen collected and formatted into a computer implemented data base with software developed for storage, retrieval, and generating files of selected data in response to information requests and for statistical analysis of relationships among various coal parameters. How It Works Coalbed methane data is obtained by the Bureau's direct method test on exploration coal cores. The test involves sealing fresh coal cores in desorption canisters and periodically bleeding the gas into a water-filled, graduated cylinder to measure the volume of gas released. Coalbed methane data collected over the past 9 years have been entered into a computer-implemented data base for efficient retrieval and statistical analysis. Data base processing is accomplished with a commercially available storage, sorting, retrieval, and report writing software package (Datatrieve 11). Information requests from the coal industry are processed with the system, and the data in the desired output format am printed and forwarded to the requestor. Information such as coalbed name, location (state and county), depth of sample, gas content, and coal rank are available from the system. The data can be used for

Jan 1, 1982

By Matthew J. DeMarco, Anthony T. Iannacchione

Coal bumps have presented serious mining problems in the U.S. throughout the 20th Century. Fatalities and injuries have resulted when these destructive events occur at the working face. Persistent bump problems can result in abandonment of large reserves or lead to premature mine closure. Through the years, alternative techniques such as artificial supports, extraction sequencing, destressing, pillar design changes and specific pillar retreat practices have been successfully implemented to mitigate coal mine bumps. Several techniques have evolved for room-and-pillar operations that control the way the roof rock breaks, regulating the manner in which stresses are redistributed in the mined section. Special mine layouts employed in longwall mines have also proved to be successful in safely redistributing or containing excessive loadings. However, with ever increasing production rates, greater overburdens and new mining systems, the need to evolve even more effective bump control designs will continue to challenge the U. S. coal mine industry.

By M. J. Sapko

The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) has conducted full-scale explosion experiments, to evaluate the strength characteristics of various seal designs, used for safely isolating worked-out areas in underground coal mines. Large-scale explosion tests conducted within the multiple entry section of PRL's Lake Lynn Experimental Mine (LLEM) is currently the only accepted test method used by the Mine Safety and Health Administration (MSHA), for deeming a seal design suitable for use in American mines. These explosion tests are labour intensive, expensive to conduct, and can interfere with other critical underground safety and health research programs conducted by NIOSH. The PRL has developed an alternative seal evaluation method, based on a hydrostatic pressure loading concept that can facilitate the in situ testing of seals in an operating mine. Two chambers within LLEM and one within PRL's Safety Research Coal Mine (SRCM) were used for hydrostatic pressure loading various seal designs. The results from these chamber tests compare favourably with those from the large-scale explosion tests in the multiple entries. In addition to testing seal designs at the required 20 psi static pressure level, the chamber test approach also allows for the determination of the seal's ultimate design strength. Six-scaling relationships for predicting the strength of seal designs as a function of entry size are also presented.

By Barbara J. Halpern

There?s no denying that mining is a male-dominated industry. Yet thanks to technologies developed over the last 20 years, societal changes in sex role stereotyping, individual determi­nation, and the willingness of companies to train women, there are no jobs in mining today where women are not represented. Women are drillers and electricians as well as drivers of heavy equipment and haulpack trucks. They perform jobs ranging from field exploration and metallurgy to clerical and janitorial and warehousing positions, from prospectors and underground blasters to geologists and land reclamation experts, from communicators to legal experts on mining law and more. The Women?s Mining Coalition, founded in 1994 to shepherd responsible legislative mining reform, estimates that 20 percent of the workers in the mining industry are women. Although women are concentrated in clerical and adminis­trative jobs, at least 10 percent are in non-traditional, hardhat jobs, claims the group. There are women in management, but the numbers in senior management remain small, especially in larger companies.

Feb 1, 1998

By D. Hurrington

For severlrl 1e1.rs the Bureau of Mines has studied dust and ventili in metal mines a.s a.tfeoting the hea.l th, safety, and efficiency of underground workers. From its beginning this work haa been directed by G, s. Rice, chief mining engineer, A. cooperative agreement was ma.de in 1915 with the u. s. Publi Health Service; since that time tield obmervations 1n metal mines in Arizona, California, Idaho, Montana, Michigan and Nevada, and less extensive observation, in several other States have been made by mining engineers of the U, s. Bureau of Mines, and doctors of the u. s. Pu.blic Heal.th Service. Most of the analyt:J:eal work has been done by chemists, petrographers, and other specialists in the Pittsburgb station ot the Bureau of Mines, Numerous articles have been printed by the otticial and the technical press on this important in•estigation; 1n response to the need for a btiet bibliography of this literature. it has been compiled to facilitate accp1,intance with published data ot1. the subject,

Jul 1, 1922

By C. M. Mason

A series of gelatinous permissible explosives was prepared with increasing sodium nitrate content and subjected to an improved technique for evaluating incendivity in coal dust-air and coal dust-gas-air mixtures. Those explosives containing an appreciable amount of sodium nitrate were found to be very hazardous in coal dust-air and coal dust-gas-air mixtures.

Jan 1, 1969

By J. B. Janus

This Bureau of Mines publication updates a series of reports on the quality of coal purchased under specifications for Government use. Listed are analytical data on the composition and quality of tipple and delivered samples of coal collected during the period July 1975 through September 1976.

Jan 1, 1977

By Rad B. Langston, Ted J. Williams, John A. Marjerison, Rimas T. Pakalnis, Tom M. Brady, Doug C. Bayer, Mark J. Bren

Underhand cut and fill mining methods are used at the Lucky Friday, Stillwater, and Galena mines in the western US in an effort to safely mine in difficult ground conditions and as a primary mining method where access below the ore is limited. The method has evolved at each mine to meet the unique situations associated with their milling procedure and mine layout. Details of the operational aspects of the backfilling and mining cycles at each mine are presented in this paper, accompanied by a summary of the mechanical properties of the backfill and its in-situ geomechanical behavior.

Develop a metal substitute which is more plentiful and less expensive than the metals currently being used in high performance, permanent magnets, while maintaining the quality of the magnet. The New Alloy The rare-earth metal used in most high performance magnets is samarium, an expensive metal of limited availability. Cobalt is also used in high performance magnets, but supplies of this metal also are limited because it is not domestically mined and must be imported. The Bureau of Mines embarked on research to find a less costly domestic: metal source for use in industrial magnets. The alloy found most promising consists of mischmetal, a relatively abundant, naturally occurring mixture of rare-earths, which can be used as a replacement for samarium. Additives of copper, magnesium and iron used in combination with mischmetal aid in replacing some of the cobalt needed for the magnets.

Jan 1, 1983

By J. E. Chilton

Regular monitoring for methane gas is required near working faces in gassy underground mines where the potential for methane ignitions is greatest. However, high concentrations of methane can also accumulate outby the face where methane levels are monitored less frequently. Wearing a personal methane monitor equipped with an alarm could protect persons working in these outby areas from injury or death due to methane ignitions. The National Institute for Occupational Safety and Health (NIOSH) has conducted studies to evaluate methanometers that could be used as person-wearable monitors. For the present study, seven different person-wearable monitors that are not currently approved for underground use were evaluated. This paper describes test procedures used to evaluate performance of methane monitors that could be used underground for continuous personal monitoring of methane. The information in this report provides data that allows the reader to make side-by side comparisons of these instruments.

By Alan H. Goode

The advancement of high-temperature drilling fluid technology for application in geothermal environments is part of the Bureau of Mines program for more efficient development of our Nation's energy resources. The bentonite constituent of water-base drilling fluids is sensitive to destabilization by high-temperature and salinity. A substitute material for bentonite, phosphate slime, which is reported to be saline resistant, was considered. These studies show that spray-dried slime suspensions have more favorable rheological behavior, but poorer filtration properties, as compared with bentonite suspensions.

Jan 1, 1975