Search Documents

By G. L. Fitzpatrick

Preliminary results of an experiment in seismic holography indicate that the techniques of acoustical holography may be successfully used with seismic waves to determine the size and general shape of underground objects. This experiment was carried out under field conditions on a moderately large scale compared with the typical laboratory experiments in acoustical holography. The object to be mapped was a 100-foot-diameter, spherical, low-velocity zone of explosively fractured rock in oil shale at an average depth of 80 feet. The seismic wavelength of the Fourier component wave used in making the seismic holograms was 50 feet at a frequency of 140 cps. The hologram sampling aperture was 226 feet square and was sampled by 441 geophones in a 21 by 21 rectangular array. One novel aspect of the experiment was the use of a wide-band polychromatic explosive source of seismic waves rather than a narrow-band quasi-monochromatic vibrator source. A successful laser reconstruction of the object image from a lensless Fourier-transform hologram in the form of a 5/l6-inch-square photographic transparency is illustrated. The size of the underground object measured from the laser reconstruction of the object and the size inferred from a knowledge of the amount of explosives used to fracture the site and the tensile strength of the oil shale are found to agree.

Jan 1, 1972

By J. M. Goris

The U.S. Bureau of Mines is conducting research on cable bolt ground supports to assess their material and support properties, to provide design criteria for using cable bolt supports as roof control systems under various types of underground mining conditions, and to provide a mathematical model of cable bolt support systems. Part 1 describes laboratory studies of the support properties of cable bolts made of conventional steel cables and provides recommendations on such topics as the use of thick grouts, selection of breather tubes, and reduction of water bleeding in cement-based grouts. The studies evaluated both single and double cables; effects of different embedment lengths, water-cement ratios, and grout curing temperatures on support strength; effects of use or nonuse of breather tubes; pumpability and water-bleeding properties of grouts; and the strength properties of sand-cement grouts. Part 2 will cover the strength characteristics of birdcage cable bolt supports, epoxy-coated cables, and cables with steel buttons attached.

Jan 1, 1990

By H. Kenworthy

Small batches of fluorspar flotation concentrates were made into nodules and pellets on a laboratory scale. Several of these were rated acceptable by laboratory evaluation methods. The most satisfactory pellets were produced by mixing fluorspar with about 12.5 percent of water, by weight, and 4 percent of organic binders. These binders) for the most part) originated from petroleum and wood-pulp industries. They were generally difficult to handle and were not easily incorporated with the fluorspars tested. Most of them seemed to have an aversion for damp fluorspar and had to be forcibly mixed with the fluorspar; which was then formed into pellets by pressure. Substitution of fuel oil in varying amounts in the binders enhanced the mixing and penetrating qualities of these binders but at the same tire tended to make the pellets more porous. Tall oils performed the same function to a lesser degree and usually decreased the water absorbency of the finished pellets. Heat-treating temperatures to set up these binders were moderate -about 5000 F. for 30 to 50 minutes was usually enough for both drying and heat treating. Nodules made with 1-1/2 to 2 percent of bentonite as a binder were easily mixed and formed. They required a high degree of heat (about 1,500° F.) to develop their strength and were quite water-absorbent when finished. Two fluorspars were examined for weight and fluorite loss after heat treatment at similar temperatures. Both showed a definite wej.ght and analytical loss of fluorite. Bentonite was used also as a binder to successfully nodulize finely ground oxides of iron, manganese, and nickel.

Jan 1, 1951

By Virginia E. Gleason

In this report, recommendations are made for programs to develop workable techniques to stop or prevent acid mine drainage formation in those underground coal mines where acid production could take place. These recommendations include development of mine closure technology, development of surface water infiltration control procedures, study of the effect of roof collapse on mine water characteristics, evaluation of the long-term effects of flooding underground mines above drainage, investigation of the effectiveness of section sealing in active mines, development of a simple model for predicting mine water quality and quantity, preparation of a manual on mine drainage abatement procedures, and development of a program to disseminate information on mine drainage abatement to the coal industry. These recommendations are based on an in-depth evaluation of information acquired over years of research on acid mine drainage formation, on numerous laboratory and field studies of methods of preventing or minimizing acid mine drainage formation, and on review of the geological, hydrological, and mineralogical factors involved. There are 772 references.

Jan 1, 1978

By Philip C. Tully

[This bibliography contains 3,655 different citations to technical and scienfic literature on helium and alpha-particles, abstracted by 13 abstract service iblicatlons during 1964. Multiple subject classification increases the total number of entries to more than 5,800. Helium citations are listed by 22 major assifications, alpha-particles by 12]

Jan 1, 1970

By Lathrop E. Roberts

The opinion is general among smelter operators that magnetite formed in the converter and reverberatory furnace has much to do with the loss of copper in the slag. Its action appears to be due in part to its relatively high infusibility, chemical stability, and specific gravity, as a result of Which it tends to form a layer of highly viscous "magnetite mush" between slag and matte. Particles of matte which might otherwise settle out of the slag are unable to pass through this layer. Maier and Van Arsdele have shown that the inclusion of grills of matte in the slag is also at tires very probably due to chemical reaction between magnetite and the constituents of the matte. In smelter control and in any laboratory study of slats the determination of magnetite is therefore a matter of some importance. The difficulties in the ray of making such a determination with any accuracy are rather obvious. Iron may occur in slag as ferric oxide, magnetite, various intermediate oxides, sulphides, silicates, as free metal, and in solid solution of several of these substances. Even if only the total iron content is to be determined, accuracy can be obtained only by painstaking and time-consuming separations from interfering elements. The determination of ferrous, ferric, and free iron in the presence of each other is a difficult matter under the most favorable conditions, and when present in a slag the difficulties are increased by the refractory nature of the sample, by the presence of sulphides, and by such elements as vanadium and molybdenum.

Jan 1, 1931

By Lathrop E. Roberts

[The opinion is general among smelter operators that magnetite formed in the converter and reverberatory furnace has much to do with the loss of copper in the slag. Its action appears to be due in part to its relatively high infusibility, chemical stability, and specific gravity, as a result of which it tends to fern a layer of highly viscous. "magnetite mush" between slag and matte. Particles of matte which might otherwise settle out of the slag are unable to pass through this layer. Maier and, Van Arsdale4 have shorn that the inclusion of prills of matte in the slag is also at times very probably due to chemical reaction between magnetite and the constituents of the matte. In smelter control and in envy laboratory study of slats the determination of magnetite is therefore a matter of some importance. The difficulties in the ray of making such a determination with any accuracy are rather obvious. Iron may occur in slog as ferric oxide, magnetite, various intermediate oxides, sulphides, silicates, as free metal, and in solid solution of several of these substances. Even of only the total iron content is to be determined, accuracy can be obtained only by painstaking and time-consuming separation ions from interfering elements. The determination of ferrous, ferric, and free iron in the presence of each other is a difficult matter under the most favorable conditions, and linen present in a slag the difficulties are increased by the refractory nature of the sample, by the presence of sulphides, and by ouch elements as vanadium and molybdenum.]

Jan 1, 1931

By P. D. Kovscek

The Bureau of Mines equipped a longwall shearer with a water-jet-assisted mechanical cutting system to determine the effect of the high-pressure sprays on machine performance, airborne dust levels generated, and size of particles formed. Testing was conducted on a simu-lated coal block (coalcrete) while cutting at a water pressure of 190 psi and at water-jet-assisted pressures ranging from 1,000 to 6,000 psi. The shearer motor energy used by the shearer while cutting coalcrete was determined for each cutting condition. Results indicate that the motor energy required by the shearer for each ton of material cut did not vary significantly as the water pressure was increased. Results of dust measurements recorded near the cutting drum indicate that at water pressures above 3,000 psi, dust reductions up to 85 pct were achieved com-pared with cutting with conventional sprays. Analysis of the particle size distribution during cutting showed that increasing the water pres-sure resulted in increased median particle size. In light of these results, various mechanisms for water-jet-assisted cutting are discussed.

Jan 1, 1986

By E. D. Calvert

This Bureau of Mines report discusses the electric-arc reduction of zirconium and hafnium oxides with carbon yielding a metal-metallic carbide mixture. The carbon to oxide ratio in the feed determines the metal to carbide ratio in the product. A sample of this product was produced -or testing as a feed for the deBoer iodide-dissociation process. A new technique for producing pure carbides is described, which uses the intense heat of the arc to volatilize the carbide. The condensed vapor form , crystals of nearly stoichiometric carbide, INTRODUCTION This research examines the preparation of refractory metal carbides in the controlled atmosphere electric-arc furnace.

Jan 1, 1962

Phase I of U.S. Bureau of Mines contract H01220S3, "Improved Sensors and Fire Control Systems for Mining Equipment, II was an investigative effort involving study of the fire problem and preliminary design of a fire protection system. Overall contract objectives included three basic efforts: * Identify problems * Develop a design * Demonstrate a system The first two efforts were conducted during the period June through November, 1972. Phase II will involve testing of system components; construction and testing of a mockup; and demonstration of the system on a truck to prove its effectiveness under actual operational and environmental conditions.

Jan 1, 1972

By M. A. Trevits, J. E. Urosek, A. C. Smith, M. P. Valoski

The National Institute for Occupational Safety and Health (NIOSH), in partnership with the Mine Safety and Health Administration (MSHA), is conducting research to test, evaluate, improve or modify coal mine fire-fighting strategies and methodologies through large-scale tests. Since wood is the second most abundant fuel available during a coal mine fire, it was decided that series of large-scale wood crib fire tests were needed to measure the products of combustion and to observe the capability of commonly available direct application fire suppression equipment, namely, fire extinguishers, water and gas-enhanced foam. This paper discusses the wood crib fire tests, provides insight into the products of combustion and describes observations made during the application of the fire suppression agents.

By A. A. Berk

The Bureau of Mines devised a test nipple for the field study of corrosion in the condensate-return lines of Federal heating plants. Corrosion surveys, made with this device, showed that the deterioration of the piping was caused principally by carbonic acid in the steam condensate. Corrosion problems were brought under control when the carbonic acid concentration in the condensate was decreased. In many instances, this was effected by decreasing the total carbon dioxide content of the feedwater; in others, the condensate acidity was neutralized with volatile, alkaline chemicals. Filming treatment with octadecylamine, reported successful in controlling return-line corrosion in industry, was much less effective in Federal area-heating plants. Laboratory study by the Bureau disclosed that octadecylamine is unstable in heating systems. Analytical methods were developed for this chemical and its degradation products in heating-plant condensate. Field surveys, in using these methods, confirmed the instability of the filming material. Laboratory tests showed that the degradation products are not useful film formers. Since filming treatment has little effect on condensate corrosivity, the piping was corroded where it was not coated by the treatment chemical.

Jan 1, 1962

By R. W. Stahl

An emergency is defined as an unforeseen combination of circumstances that calls for immediate action. When applied to a coal mine, an emergency may call for prompt removal of the men to the surface through travelways other than the haulageway or intake airways, which are generally contaminated with irrespirable air as a result of an explosion or fire. Therefore, maintenance of adequate and travelable escapeways from all working areas of a mine is vitally important insurance against disaster. Several mine disasters could have been avoided if well-defined escape routes had been provided and made known to all mine employees. Such occurrences, unnecessary as they generally are, unfairly indict the industry when only a small segment thereof is involved. As a result of a rather recent disaster, which might not have happened if good escape routes had been provided, the Bureau of Mines decided to delve into the escape procedure to determine (1) what is being done in the industry and (2) what might be done at reasonable cost.

Jan 1, 1962

By Galen G. Waddell

The Deep Creek zinc and lead mine afforded an excellent example of a relatively small underground mine operation that approached the low mining costs of large, highly mechanized mines, An open stope mining method incorporating sublevel benches and vertical long holes was used (fig. 1). Detailed descriptions are given on the exploration program, stope development, stoping procedures, and pillar removal. Pressure grouting was used to check the inflow of water and thus prolong the life of the mine. Statistics on mining costs and on electric power consumption, haulage from mine to mill, and milling costs are included.

Jan 1, 1963

By J. R. Ruark

Because of the importance of oil-shale reserves the Bureau or Mines resumed research investigations in this field beginning in 1944. The Bureau early decided to build a Large-scale demonstration plant to accomplish the dual purpose of obtaining design data and to produce crude shale oil for refining studies. Two 40-ton-Capacity batch N-T-U (Nevada-Texas-Utah) retorts were completed for this purpose in 1947. After a preliminary operation, the plant was used to investigate process variables of air rate, recycle gas rate, and shale particle size and crude. Correlations obtained from these variables are presented in this report. Researchers concluded that recycle gas was not necessary for efficient operation of the process. Short comings of the batch method of processing the oil shale are pointed out in the report. Several periods of prolonged production operations were carried out. During these periods, the retorts were operated to produce as much crude oil per day as possible. The lifetime operation of the N-T-U retorts was divides into three periods, namely, preliminary operation, process variable study, and production operation. During the preliminary operation, 187 runs were made with a total of 7,596 tons of raw shale used to produce 3,688 barrels of crude shale oil. During the process variable study, 179 runs were made with a consumption of 7,494 tons of raw shale and a production of 4,218 barrels of crude shale oil. The production operation consisted of 554 runs in which 22,457 tons of raw shale was used to produce 12,359 barrels of crude shale ail. The overall total for the lifetime operation of the retorts consisted of 920 runs with a total consumption of 37,547 tons of raw shale and a production if 20,265 barrels of crude shale oil.

Jan 1, 1956

By Richard J. Mainiero, James H. Rowland III, Marcia L. Harris

This paper reviews the potential hazards posed by the toxic fumes produced by detonating explosives in surface mining and construction operations. Blasting operations produce both toxic and nontoxic gaseous products; the toxic being mainly carbon monoxide (CO) and the oxides of nitrogen (NOx). The quantity of toxic gases produced by an explosive is affected by formulation, confinement, age of the explosive, and contamination of the explosive with water or drill cuttings, among others. Techniques to protect workers and the public from the potential hazards of explosive-related toxic fumes are discussed. These include: • Minimizing the quantity of toxic fumes produced. • Determining where the fumes may go so workers and neighbors can be moved out of harm’s way. • Preventing the fumes from moving towards workers and neighbors. • Monitoring the air near workers and neighbors so they can be relocated if fumes appear. • Ventilating structures or confined spaces until CO falls below a hazardous concentration.

By K. L. Paciorek

The aim of the present study was to determine the thermal oxidative behavior of materials used in coal mines, with emphasis on the type and relative concentration of the products, in particular the toxic species formed. To supplement this work and to gain understanding as to the type of products possibly formed and also to assess the limitations and advantages of the various analytical methods used a literature survey of the past investigations performed on the compositions of direct interest to the subject program was conducted. The compositions thus covered were cellulose, polyvinyl chloride, neoprene, urethanes, polyamides, polyesters, polyethylene, epoxy, phenoxy, urea-formaldehyde and melamine formaldehyde resins. The results of this review are compiled in the Appendix. The experimental work consisted of thermal oxidative degradation of 36 materials and 4 composites using a stagnation burner apparatus developed in these laboratories which affords a dynamic system approximating somewhat the conditions encountered in underground coal mines. This technique as employed during this program gave only the relative product concentration at specific periods of the decomposition process, The advantage of this approach is that in this manner screening of materials can be accomplished in conjunction with some assessment of the decomposition rate as influenced by temperature and material composition. Limited static tests were performed using a sealed tube method. The materials studied were grouped according to their compositions. The following were the main groups: (a) polyvinyl chloride-containing materials, (b) neoprene compositions, (c) rigid foams (urethanes, isocyanates), (d) miscellaneous materials (including jute, fiberglass, polyethylene and some articles of unknown composition), (e) coal and fluids (phosphate esters, organic esters, oil-water emulsions), and finally (J) composites. The latter comprised a mixture of a phosphate ester fluid with (a) coal, (b) a representative polyvinyl chloride sample, and (c) a neoprene type composition.

Jan 1, 1972

By A. R. T. Denues, A. P. Rowles

"INTRODUCTION Summarized data developed by J. E. Crawshaw and E.J. Murphy, 4/of the Explosives Division of the Bureau of Mines, suggesting marked variations in oxygen condition in three permissible explosives, have been reported 5/. Such variation is of interest in other work, it having been shown, for example, that the oxygen condition may have marked effect upon the products 3/ and the propulsive strength 7/ of explosives. It seemed that a more detailed presentation and more usual statistical analysis of these data might be of considerable general interest and not complemented in the literature.This report presents both the original data developed by Crawshaw and Murphy and the results of a simplified but seemingly acceptable statistical analysis of these data. The logical ground for this analysis might seem somewhat questionable because of the lack of systematic information concerning the extent of errors in the analytical procedure but the data show that there are several cogent and seemingly unequivocal indications of real heterogeneity in the explosives."

Jun 1, 1942

By R. Stefanko

This first Annual Report covers the work on Contract No. H0377043 "Cable for Face Equipment", from August 1, 1977 to July 31, 1978. It reports the progress in the three areas of over-and short-circuit protection, cable ampacity research and cable couplers. Field trips have established many interesting facts related to circuit breaker settings and cable size. For example, the determination of cable sizes depends on the RMS duty cycle current determined by a particular piece of equipment, but the actual selection of the cable to be used is often a function of the maximum allowable circuit breaker instantaneous settings as specified in Title 30. In order to avoid nuisance tripping as a result of instantaneous starting current field, laboratory and analytical studies are being conducted to determine proper settings and cable sizes Also an extensive program has been established to monitor the performance of high voltage cable couplers and determine their modes of failure. Various equipments are being designed for laboratory testing, and an extensive reeled cable experiment is also under way.

Jan 1, 1978

By Jürgen F. Brune, Liming Yuan, Alex C. Smith

To provide insights and assistances for the optimization of ventilation systems for U. S. under-ground coal mines facing both methane control and spontaneous combustion issues, a computational fluid dynamics (CFD) study is being conducted to investigate the effect of the ventilation scheme on the prevention of spontaneous combustion in longwall gob areas. This report focuses on the flow patterns within the gob under three different ventilation systems; one-entry and two-entry bleederless systems as well as a three-entry bleeder system. The gas flow in the caved gob area is simulated as a laminar flow through porous media while the gas flow in ventilation airways is simulated as a fully developed turbulent flow. The air flow patterns are visualized using flow path lines. Air velocity contours and vector data are also obtained. The possible location of critical velocity zones where the gob is most liable to spontaneous heating is discussed.