Search Documents

By William J. Karwoski

To improve rock-burst control in deep vein mining, a field demonstration has been carried out by the Bureau of Mines to test a new rock-burst control concept--rock preconditioning in advance of mining. The procedure is to fracture the major rock-burst-prone zone during the development of each level before production mining. This allows initial mining to begin in a preconditioned zone and later mining from the level below to end in a prefractured or preconditioned pillar zone that is relatively burst-free. This full-scale field demonstration was carried out On the 7700 level of the Hecla Mining Co.'s Star-Morning mine. An expected burst-prone zone along the main vein between 7 and 10 crosscuts, some 250 feet long by 40 feet above and below the level, was preconditioned by blasting a fanlike ring of drilled holes from each crosscut. The drill holes, up to 100 feet long and 4 inches in diameter, were loaded with high explosives and shot. About 4,550 feet of drilling and 9,000 pounds of explosives were involved in the effort. Comparison of preshot and postshot data from monitoring instrumentation indicated that the blasting did fracture the rock in the planned zone and did result in an immediate stress decrease and softening of rock. The field data compared favorably with predicted results from a finite-element computer model simulation of the destressing. Based on observations made during mining and on the data from the Hecla rock-burst monitoring system, there is no doubt that this preconditioning in advance of mining demonstration resulted in much-improved rock-burst control during first-floor mining. It was also concluded that preconditioning the vein was more effective than preconditioning the wall rock.

Jan 1, 1979

By H. R. Pierce

Bureau of Mines engineers end others have endeavored to deter-nine a fundamental method for gauging the capacity of gas wells to deliver gas under different pressure conditions. Their studies show that for accurate gauging two factors must be determined: (1) The actual pressures at the face of the sand in the well (usually referred to as "at the sand"), acid (2) the relation between such pressures and the rates. of flow of c as through the sand. This paper, the first of a series, describes a method of attacking the problem of determining the actual pressures at the sand by means of observations of pressures and volumes at the well head.

Jan 1, 1929

By William F. Keyes

Greensand, which is widely distributed in the Eastern United States, was produced in 1975 only by Inversand Co., a subsidiary of Hungerford & Terry, Inc., near Clayton, N.J. Production and sales information are not available for publication. Raw greensand produced by the company was sold for agricultural use as a soil conditioner. Processed greensand was used by manufacturers as filter media in equipment for the removal of manganese, iron and other elements from water. The University of Delaware received a grant of $17,051 from the Bureau of Mines early in 1976 to continue its studies of the effectiveness of greensand in removing metallic contaminants from waste waters.

Jan 1, 1977

A mobile vacuum sweeper to remove loose coal and coal dust from underground coal mine workings was designed, built, tested, and evaluated. The design was based on an extensive test program. Pick up and conveying rates vs. air volumes, velocities, and nozzle shapes were determined for coal rubble in a laboratory pneumatic handling system. A gas/solids separation system was developed and tested in the laboratory capable of separating the solids loading from the vacuum system air stream to the very high degree required to preclude degradation of the ambient (mine) air. Two designs were made, one for belt conveyor and one for general district cleanup. The belt cleanup machine was chosen for test and demonstrated in an underground coal mine performing cleanup work in belt haulageways and on ribs.

Jan 1, 1975

By Tuncel M. Yegulalp

The objective of this study was to categorize mining operations in the stone, and sand and gravel industries into areas of similar ground control functions and define initial factors affecting operational safety in each area, by means of utilizing publicly available data, telephone interviews and on site observations. The findings and recommendations presented in this report are based on the information collected during the two phases of the project. They also contain, in part, the collective qualitative opinion of the operators with respect to government rules and regulations on ground control safety and the implementation of these rules and regulations by government inspectors.

Jan 1, 1981

By John G. Palmer

Continued development of an especially impregnated silica gel capable of reversible chemical detection of carbon monoxide (CO) was reported. The affects of changes in mine-related ambient conditions on the detection catalyst's response were explored. Temperature, humidity, and several interfering gases were found to affect the detection catalyst. The interferents include hydrogen sulfide, nitrogen dioxide, acetylene (and methylacetylene), and ammonia. High humidity decreased the detection catalyst's sensitivity to carbon monoxide for some formulations. Increasing temperature generally decreased the reaction time of the detection catalyst with carbon monoxide. Badges and carriers for the visual presentation of the detection catalyst were constructed. Several variations of these devices included provisions for absorbants and filtering agents which help protect the detection catalyst from gaseous interferents. A variety of catalyst support agents were tested in an effort to find the most suitable. Included were alumina, magnesium oxide, magnesium silicate, and several forms of silica gel. In addi tion to free-flowing forms of these sorbents, thin layer chromatography plates coated with cellulose, alumina, and silica gel and newly developed PTFE entrained silica gels were examined. A limited physical, chemical, and mechanistic characterization of the detection catalyst and the materials used to prepare it has been carried out. Metal component ratio studies, spectral, analytical, pH, and rate measurements were done.

Jan 1, 1982

By Dana T. Updyke

An evaluation was made of one of several improved underground communication systems sponsored by the U.S. Bureau of Mines. The system evaluated was installed in a typical metal/non-metal room and pillar mine and utilized UHF repeaters connected to a unique distributed antenna and passive reflector system which provided mine-wide communications. A microprocessor controlled data collection system was assembled and installed for the evaluation. Data consisting principally or times and durations of messages and identities of the originating transceivers was collected between February and August of 1982 (6 mos.). Analysis of the data shows that the principal benefits are reduction in time required for unscheduled maintenance and repair, enhancement of safety, and better coordination of production activities. A cost benefit analysis shows a net benefit over cost, although it is also concluded that the capacity of the system is greater than can be justified by current activity in the mine.

Jan 1, 1983

By Walter B. Lenhart

This paper is one of a series on milling methods and costs being. published by the Bureau of Mines. The milling practices and special problems relating to grinding, tailings disposal, and choice of a treatment process at the Cardinal mill are discussed. The property of the Cardinal Gold Mining Co. is about 18 miles southwest of the town of Bishop, Inyo County, Calif., at an altitude of approximately 8,500 feet. The camp has been designated Bishop Creek by the postal authorities. The property comprises 33 mining claims, including fractions and millsite in sections 19, 20, 29, and 30, T. 8 S., R. 31 E. These claims are located in a general way along the strike of a band of quartzite.

Jan 1, 1938

By R. R. Sayers

"The number of investigations reported during the past year indicates that control of the health hazard due to abnormal air conditions is still a matter of serious consideration in the mining, metallurgical, and allied industries.Australia. - In an investigation into the health and working conditions of employees in the mining industry of Tasmania and Victoria3, it was found that although pulmonary tuberculosis may occur early in life, silicosis is e disease of slow evolution and does not appear frequently under the ace of 40. A period of at least ten years in the industry was found necessary to produce silicosis, and in no case was the disease found in those who had not worked underground. A very high incidence of silicosis was found in all fields among those who had worked underground 20 years and longer. There was some evidence that silicosis complicated by tuberculosis may occur earlier than uncomplicated silicosis.England. - In a paper presented before the Section on Occupational Diseases of the British Medical Association, Dr. E. L. Middleton, the medical inspector of factories, called attention4 to the occurrence of silicosis in various industries throughout the country.punitive on some quite harmless industries. Thus Middleton says: ""Where the amount of dust is small the action of the phagocytes is likely to be effective, but where it is great . . ."" What dosage is indicated by ""small"" and ""great"" in this connexion? If the meaning of ""small"" were known, would it be correct to go on to say, as he does, ""each successive dose of silica produces a summation of effects""? Then, again, would it be fair to say ""a comparatively brief period of exposure may be the only determining factor""? What, in minutes, hours, or days per week, per month,' or year, is intended by ""a comparatively brief period""? ""Intermittency of the process"" is another expression used in summing up the reasons for and against a standardization of air purity by a gravimetric process or enumeration of the particles; the arguments against such a standardization are, by Middleton, considered strong, but they are by no means convincing to us. A standard has been accepted in respect of the amount of lead in milligrams per 10 cubic metres of air; Dr. Ronald Lane showed in another paper read that adherence to this makes the occurrence of poisoning highly improbable. Mavrogordato has placed on record figures of silica dust at different stages of the improvements in the workings of the Rand mines, and such a control is in constant operation in them today.We emphasize these points because apparently the Government has taken the unusual course of legislating first and postponing inquiry to a later date, as in the ""Various Industries (Silicosis) Scheme, 1939."" The insurance companies also have a considerable interest in the matter of compensation for the silicosis risk. Where exposure - as in the refractories industries, the grinding industries, sandstone industry, and pottery industry - is day in and day out, they rightly demand a premium far higher than for any other disease scheduled under the Workmen's Compensation Act - 5 per cent on the wages bill. row every industrial employer, such as the paint and varnish manufacturer, who has a sack of crushed silica in his store .room, from which he extracts once a week enough to make a paste With spirit and add to his other ingredients in order to give them the necessary ""bite,"" becomes involved, and may have to abandon the use of the material or pay 8 per cent on his wages bill for an absolutely negligible risk.. For meting out justice standardization seems urgently called for."

Feb 1, 1930

By Jeremy P. Doolan, Leigh B. Neindorf, Geoff W. Capes

The development and use of rock mass classification tools have been a key component for improving stope design over the past 4 years at the Xstrata Zinc George Fisher Mine in northern Queensland, Australia. In 2003, stope extraction data from 3 years of open-stope mining provided an excellent situation to review the assumptions in the feasibility study. Extracted stope profile information, drillhole geotechnical data, underground observations, and oral and written communication were used to develop a thorough stope reconciliation performance database. With-out collecting the back analysis data and presenting the data in a usable format, engineers are left to debate opinion instead of engineered judgment. This can lead to biased and uninformed design parameter choices with the potential to repeat poor design. This paper demonstrates some effective, practical examples of empirical data collection where rock mass classifications tools were developed and used to create improved confidence in predicting stope stability and failure profiles. The work contributed to design changes that resulted in a reduction in stope hangingwall dilution and an increase in head grade while continuing to ramp up production from 2003–2005.

Jan 5, 2007

By L. Douglas Smoot

This research program was a theoretical and experimental study to improve understanding of the mechanisms of flame extinguishment in methane-coal dust-air-suppressant mixtures. This final report is a summary of work conducted during this grant, sponsored by the Bureau of Mines. Work under this new grant closely followed a recently completed contract for the Bureau of Mines that was conducted at this laboratory, and results of the earlier contract are also summarized in this report, as required in the grant work statement. The experimental effort was concentrated on supplementing the limited data available to describe laminar flames in methane-coal-air-suppressant mixtures. The theoretical effort was devoted to developing a comprehensive model that could be used to explain and extrapolate the experimental data. Selected for study were the following flames: Methane-air; methane-air plus KHCO , KNO3, K C204, KBr, Al203 or Monnex; methane-coal dust-air; coal dust-air with size, volatiles content, and concentration as variables, and coal dust-air plus KHCO3, KN03, KBr, NaCl or CaC03.

Jan 1, 1978

Study to develop a new and more cost effective equipment system, incorporating a winch-pulled dozer blade, for leveling spoil and performing reclamation of area strip mines.

Jan 1, 1975

By Kenneth R. Maser

This report describes a research and development program sponsored by the United State s Bureau of Mines. The purpose of the program was to develop reusable explosion-proof bulkheads for a cross-cut emergency shelter, and to study the implementation of such bulk-heads, and the resulting shelters, as part of an emergency escape plan in a normal coal mining environment. The first part of this report reveals a number of significant conclusions regarding the application of emergency shelters. A study of the cause s of, and the conditions prevailing during a mine emergency indicate s that ideal placement of the shelter s would be midway along developing entries, and at the inter section of butt and main entries. The proper spacing of shelters is based on the travel capability of trapped miners, which is in turn dependent on the height of coal. The life of a given emergency shelter, based on an analysis of the above information, will be anywhere from 6 months to 10 years. Consequently, some shelters are regarded as "temporary?, while others "permanent?.

Jan 1, 1975

By Edward G. Cunney

[Track in underground bituminous coal mines was investigated and technology has taken from other industries in order to Main information on conditions that impair the safety and efficiency of the track and to develop guidelines ad useful information on the constriction, inspec¬tion and maintenance of mine track. Volume l contains information oil the investigations, observed track conditions, useful technology from railroads and other industries, derivations of track condition descriptors and limits, conclusions, and recommendations. Volume 2, Guidelines, contains recommended standards and practices for mine track. It includes the relation of track conditions to safe speeds; descriptions and limits for measurable track features such as gage, descriptions of conditions for track components that are normally not measurable, such as subbase soils; construction requirements and techniques; inspection requirements and methods; and methods for managing and performing track maintenance work. As a research product, it 0005 nut repeat the summary or derivations. Volume 5, Inspection Handbook, summarizes recommended standards and procedures from Volume 2 and provides related information for read: refer¬ence by inspectors in tin mines. As a research product to be used in mines, it does not repeat the summary, derivations or references.]

Jan 1, 1977

By Jesse A. Miller

ALTHOUGH the element titanium was discovered by William Gregor in 1790, over a hundred years passed before it was put to commercial use. The first commercial application of titanium was as an alloy additive to iron and steel, and the first ferroalloys were produced domestically in 1906. Titanium pigments were developed somewhat later and have been produced in the United States since 1918. The use of titaniferous material in welding-rod coatings first gained acceptance ill the mid-30's. The metal titanium has only had commercial importance since 1948; domestic production for that year was 10 tons. The relative importance of these major uses of titanium in various forms may he gaged by the consumption of titanium dioxide (Ti02) for these purposes in 1954. Of a total of 440,000 short tons of Ti02 consumed in 1954, 95 percent of the total was consumed for pigments; 2 percent for welding-rod coatings; 1 percent for non-titanium-base alloys and carbide; and 2 percent for miscellaneous uses. The titanium-metal industry is in its infancy, but it has more than doubled its output every year from 1948 to 1954, reaching 5,370 short tons in 1954.

Jan 1, 1957

By Annie G. Smelley

The Bureau of Mines is testing a dewatering technique for phosphatic clay waste that will recover a portion of the water lost using conventional waste disposal methods and produce solids suitable for land reclamation. The technique utilizes a flocculant, polyethylene oxide (PEO), that forms strong, stable flocs that can be dewatered on a static screen followed by further dewatering on a rotary screen. In field tests conducted in northern Florida, clay wastes containing a nominal 2.5 pct solids have been consolidated to greater than 20 pct solids. The rate at which PEO-treated material continues to dewater in a mine cut also was monitored. Preliminary results indicate that PEO--treated material will dewater to 30 pct solids in 140 days. Pretreatment of phosphatic clay waste with lime and H202 was shown to improve the dewatering technique for problem clay wastes.

Jan 1, 1985

By Ralph D. Gift

This report describes a program of research to evaluate methanometry in coal mines. The program commenced by conducting an extensive state-of-the-art survey. Details of the survey are presented which includes a rating of various types of instruments that can be used to detect and record methane gas. Laboratory test data, on mine instruments tested are presented together with results from a computerized statistical analysts.

Jan 1, 1972

By Thomas M. Barczak

The U.S. Bureau of Mines has been conducting research to optimize the design and utilization of mine roof support systems. An objective of these efforts is to evaluate the mechanical and structural responses of various mine roof support systems under simulated load conditions in the Bureau's mine roof simulator. Underground studies are also made to evaluate the in situ behavior of support structures. The purpose of this report is to document practical applications for longwall face and gate road supports that have resulted from these studies. This report is not intended to be an all-inclusive manual on every aspect of support utilization, but it does provide a comprehensive assessment of practical considerations relating to the mechanical and structural behavior of these support systems. Forty-six recommendations are made to provide assistance to mine operators in the testing, selection, and utilization of longwall face and gate road supports. Many of these recommendations offer innovative solutions to everyday problems faced by mining personnel in the control of ground in longwall mining.

Jan 1, 1989

By I. Liebman

A Bureau of Mines study is in progress to determine the effectiveness of passive water barriers in suppressing coal-dust explosions. A 2.9-ft3-capacity water-filled plastic tub was found effective in suppressing dust explosions propagating at speeds of 250 to over 1,000 ft/sec. Work directed at determining the limitations of water barriers showed that the passive water barrier technique is also feasible for the suppression of weak dust explosions propagating at speeds of 100 to 250 ft/sec. For relatively slow accelerating flames, dynamic wind forces appear to be the important quantity governing fragmentation of the plastic tub and subsequent water release and dispersion, whereas dynamic impulse appears to be the significant quantity for rapidly accelerating flames. The acoustic approximation (relation between static pressure and flame or wind speed) is shown to be valid in a long single mine entry. This relationship appears to be useful in predicting the regions within a long single entry where passive water barriers are effective in quenching a dust explosion.

Jan 1, 1974

By F. A. Rutledge, H. Marstraander, J. H. Hulbert, G. A. Apell

"INTRODUCTION The inability of Alaska coal mines to supply the quantity of coal required by public and private consumers and by the armed forces in Alaska caused the Coal Procurement Section of the Alaska Department, U. S. Army, to be established. It proposed to investigate the coal deposits and to expedite production of coal. The Bureau of Mines has closely cooperated in this program and was in direct charge of exploration. As to develop and equip an underground coal mine would have taken time and the need for coal was acute, a deposit that could be prepared for mining quickly was desirable. Several such deposits of stripping coal were known to occur in the Nenana field and were examined by the Bureau. One of these, the Diamond strip mine 4 miles west of Healy, was brought into production late in the fall of 1943. This mine was operated for the Army Coal Procurement Section by the C. F. Lytle Co. and the Green Construction Co.The Roth property, or Leasing Block No. 28, in the Healy Creek Valley offered the largest available tonnage of both stripping coal and total reserves. A program of exploration by the Bureau of Mines was inaugurated in 1943 and completed in 1944. Field parties of the Federal Geological Survey mapped the area had correlated the coal beds during the 1944 and 1945 summer seasons."

Nov 1, 1946