Search Documents

By Jeffrey M. Listak

The Bureau of Mines has conducted a rock mechanics study to monitor deformation of near-seam strata above a longwall panel in the Pittsburgh Coalbed. The primary goal was to determine the height of caving immediately behind advancing longwall face supports. This study, although site specific, provides information on the caving mechanism associated with longwall extractions so that strata behavior and its interaction with longwall face supports can be better understood. Two holes were drilled, approximately 550 ft apart along the center line of a longwall panel, from the surface to the coalbed approximately 650 ft below. Various downhole geotechnical instruments were used to monitor strata deformation. In addition, surface elevation surveys were conducted to differentiate between surface and subsurface activity. This report discusses the caving characteristics of the strata as the longwall panel approached and passed beneath the boreholes. Physical property data are also presented to demonstrate the relationship between caving behavior and local geology. Data show that immediate caving of strata above the longwall face occurred at a height less than 23.5 ft and that strata behavior above longwall extractions is highly dependent upon lithology, with major disturbances occurring at weak lithologic zones.

Jan 1, 1986

By William K. Tolley

The U.S. Bureau of Mines (USBM) is currently investigating the electrochemistry of mineral flotation. A significant need in this area is greater reliability of sensors. The USBM is testing electrolytic methods to clean and condition redox-sensing electrodes to improve the reliability and extend the service life of these instruments in the harsh physical and chemical environment of mineral processing slurries. A novel method for removing scale from fouled electrodes has been developed that includes anodic polarization to 1.2 V versus the Ag/ AgC1 reference potential, followed by brief potentiodynamic conditioning. Laboratory results show that this technique removes calcarious deposits from gold sensing electrodes and returns the electrodes to useful service within approximately 10 min. Mechanical abrasion to remove the scale is thereby avoided.

Jan 1, 2010

Locating subsurface conductive solutions is important for many applications, including in situ mining and environmental protection. Drilling boreholes for sampling is expensive and can increase contamination by mixing water from different aquifers. Various noninvasive geophysical methods are available, but previous comparisons were hampered by different methods being used at different sites or at different times. The U.S. Bureau of Mines (USBM) compared methods at one site using the same conductive solution to improve the reliability of the comparisons. Locating deep (> 100 m) solutions is most difficult, SO the USBM selected methods applicable for such depths. Objective Improve the ability to locate subsurface conductive solutions by evaluating and comparing applicable geophysical methods. Approach The experiment was performed cooperatively with other agencies to increase the number of methods studied. The USBM, the University of Arizona, Sandia National Laboratories, and Zonge Engineering and Research, Inc., conducted cooperative field tests of six electromagnetic (EM) geophysical methods to compare their effectiveness in detecting salt water brine of conductivity 3.6 S/m collecting at the water table, 157 m subsurface. The brine was injected through two boreholes. The test site was the University's San Xavier experimental mine near Tucson, AZ. Geophysical surveys using surface and surface-borehole, time-domain electromagnetics (TEM); surface controlled-source audiofrequency magnetotellurics (CSAMT); surface magnetic field ellipticity, surface-borehole, frequency-domain electromagnetics (FEM); and crosshole FEM were conducted before and during brine injection. A total of 110,000 I. of brine was injected over one week, but the effective target volume of brine was much smaller because of mixing with ground water and dispersion.

Jan 1, 1994

By Richard J. Mainiero

The U.S. Bureau of Mines in cooperation with Jim Walter Resources, Inc. (JWR), Brookwood, AL, evaluated the use of sheathed explosive charges in breaking up large stones that can jam the feeder¬breaker or pan conveyor on longwalls and halt operations. Use of the sheathed charge reduced the downtime of the longwall panel to 15 to 30 min as compared with the 1 to 2 h required to drill and shoot the stone. Firing the sheathed charge at the face caused no significant damage to Iongwall equipment. Use of the sheathed charge also represented an improvement in safety by eliminating the exposure of miners to the inherent hazards of the face for extended periods of time. Another benefit, which is difficult to quantify, is the elimination of the temptation to shoot mudcaps or adobes, which is illegal in U.S. underground coal mines.

Jan 1, 1990

Flexible hoses with rated working pressures up to 40,000 psi are used when high-pressure water jets are employed to cut rock or improve the performance of mining machines. Hose failures at such high pressures can result in serious injuries to workers. The Bureau of Mines used fatigue and burst tests to investigate the failure modes of high-pressure hoses at their rated working and burst pressures. Fatigue failure, at rated working pressures, occurred when the inner liner of the high-pressure hose broke, allowing water to seep through the wire wrapping, although the reinforcement wires did not break. At the burst pressure, all hoses failed catastrophically when the reinforcement wires broke. Low-pressure hoses placed over the high- pressure hoses for safety failed to contain water released by catastrophic failure.

Jan 1, 1987

By Thomas C. Ruhe

The Bureau of Mines conducted research to determine the safe operating conditions for using recycled (used) lubricating oil from mining equipment as a partial replacement for diesel fuel to make ANFO-type blasting agents. The use of recycled oil (RO) saves energy, reduces oil imports, and reduces mining costs. Low ambient temperatures may cause these recycled oils to become too viscous for proper absorption by ammonium nitrate (AN) prills and result in poor blast performance, safety hazards, and environmental problems. To help quantify and resolve these issues, viscosity, mixing, and performance tests were conducted at various temperatures. Diesel fuels No. 1 and No. 2 were studied separately and in blends with 25,50, and 75% RO. Good quality ANFO mixes (94-6) were produced with dry absorbent prills and blended fuel (No. 1 diesel plus RO) at temperatures as low as -40° F (-40°C) with 75% No. 1125% RO, and at -20°F (-29°C) with 50/50. Diesel fuel No. 2 also made good mixes as low as -30" F (-34" C) with 75% No. 2/25% RO, and at 0° F(-18° C)with 50/50. Reference detonation velocity tests were conducted in 1.4" (3.6 cm) diameter steel pipe at 70°F (21°C) on No. 1 diesel ANFO (94-6), giving an average value of 9722 ft/s (2964 m/s). Comparison tests showed good ANFO performance at low temperatures. Blended fuel ANFO (75% No. 1/25% RO) mixed, loaded, and tested at -40°F (-40°C), produced an average velocity of 9247 Ws (281 8 m/s). A 50/50 blend gave a velocity of 8083 Ws (2464 ds) at -20°F (-29°C). Based on these results, a practical field method has been developed to help evaluate whether a specific oil blend will mix properly with AN at a low ambient temperature. This method will help to promote the safe and reliable use of RO ANFO at low temperatures, with adequate performance.

Jan 1, 2008

"An active list of permissible explosives was published in September 1935 as part of United States Bureau of Mines Report of Investigations 32S6, under the title ""Active List of Permissible Explosives and. Blasting Devices Approved. Prior to July 31, 1935."" This list included 154 brand names,Changes in the list that have been authorized subsequently placed 24 addi¬tional brands of permissible explosives on the active permissible list as a re¬sult of tests, changes in brand names, or transfer from the inactive list. Eight permissible explosives were transferred from the active to the inactive list. The present active permissible list contains 170 brand names. The brand names of the permissible explosives placed on the active list are as follows:Black Diamond Nu-Gel No. 4 By test.Black Diamond Special A,do.Burton 11, L. F. By change in name,Burton G, L. F. By test.Columbia B By change in name.Columbia C Do.Columbia D Do.Columbia E Do.Columbia. F Do.Columbia G Do.Columbia 1 Do.Columbia 2 D.Columbia 3 DoColumbia 4 Do.Columbia-Gel 1 Do.Columbia-Gel 2 Do.Genite 5, Do.Genite 7, Do.Genite G Do.Lump Coal C By test.Peerless No, 1 By transfer from inactivePeerless No. 8, L. F. Do.Tri-State Special No. 1 Do.Unilite No. 2 Do."

Dec 1, 1936

By R. O. Dannenberg

Applicability of the fluosilicate sintering process to recovering beryllium from beryl-spodumene concentrate analyzing 1.4 to 3.7 percent BeO (10 to 30 percent beryl) was investigated. The work was one phase of a Bureau of Mines research program undertaken to assess applicability of conventional processes and to devise new procedures for treating various potential beryllium feed materials. Beryllium recovery of about 70 percent in a product of 99-percent BeO grade was achieved in treating 3D-percent beryl concentrate. The process consisted of (1) sintering a briquetted charge of concentrate, soda ash, and sodium fluosilicate for 3 hours at 750° C.; (2) extracting the soluble beryllium by multiple stages of water leaching; (3) adding caustic to the leach solution and boiling to hydrolyze and precipitate crude beryllium hydroxide; (4) dissolving the crude beryllium hydroxide in sulfuric acid and separating the solution from undissolved silica; (5) sulfidizing the acid beryllium solution to precipitate heavy metal impurities; (6) adding ammonia to the clarified sulfate solution to precipitate beryllium hydroxide; and (7) converting the hydroxide to beryllium oxide (beryllia) by calcining at 900° C. About 60 percent more sodium fluoSilicate was required per unit of beryl than is used industrially in treating 10-to 12-percent BeO concentrate (80 to 90 percent beryl). Recovery decreased, and flux requirements increased, when treating concentrates containing less beryl.

Jan 1, 1963

By J. E. Pahlman

The Bureau of Mines conducted re-search to determine the resistance of basic refractories to corrosion by ash slags that would result from the burning of coal and lignite in metallurgical operations. Basic refractories are of economic interest because they are from one-third to one-half as expensive as 90-to 99-pct-alumina refractories. Static tests were performed at 1,300° C and dynamic tests at 1,400° to 1,650° C to investigate the stability of refractory specimens in a slag environment. In alkali-containing lignite ash slags, in order of decreasing resistance, magnesite, magnesite-chrome, and chrome-magnesite refractories all had corrosion resistances equal to or better than 90-to 99-pct-alumina refractories. These basic refractories formed slag penetration layers in dynamic tests, which helped protect them from further attack. Chemically bonded basic refractories in general did not have as good a resistance to slag attack as did burned refractories of the same composition. In very acidic coal ash slag, a chrome-magnesite refractory containing 30 pct MgO plus a slag inhibitor and direct-bonded magnesite-chrome refractories with 60 pct MgO had good resistance to attack. Chrome-magnesite refractories (30 to 40 pct MgO) were moderately to severely attacked, and refractories with greater than 70 pct MgO were severely attacked by this same slag.

Jan 1, 1982

By David W. Houseknecht

Probabilities of encountering coalbed discontinuities during vertical or horizontal drilling in a specific coalbed can be estimated based on analysis of mined-out areas of the coalbed where the size, shape, orientation, and distribution of discontinuities are known. The result- ant probability estimates can be applied to cost-risk evaluations of drilling programs proposed for exploratory, developmental, or methane drainage purposes in undeveloped areas of that coalbed. Data compiled from mine maps of the Beckley Coalbed in southern West Virginia were used to estimate the probabilities that discontinuities would be encountered in two illustrative hypothetical drilling programs--one for drilling vertical boreholes and the other for drilling horizontal boreholes. Analysis based on a mined-out area of the Beckley Coalbed indicated that vertical methane drainage boreholes spaced 1,000 feet apart in a square grid pattern would each have a 29 percent probability of encountering a discontinuity in a geologically unexplored area of the coalbed. It was also determined that exploratory vertical drilling could locate most of the discontinuities if a borehole spacing of 2,500 feet were used. For horizontal drainage boreholes in the Beck- ley Coalbed, the analysis indicated a linear relationship between hole length and the probability of encountering a discontinuity.

Jan 1, 1982

By O. Q. Leone

Composite diaphragms were used in the investigation of electrowinning Ti from TiC14 in a fused LiCl-KCI-TiC'2 electrolyte. Composite diaphragms tested were of two general classes--those consisting of two or more solid materials, and those which contained, in addition, a loose material. An electrowinning cell using a flat diaphragm is described. The maximum current density for these diaphragms was 300 amp per ft2. Lower currents permitted longer operation times. The composite diaphragms gave electrode efficiencies that averaged approximately 60 percent, and the electrowon titanium was of good quality--some Brinell hardnesses were as low as 68.

Jan 1, 1972

By Louis A. Turnbull, JOSEPH J. SHIELDS

The Bell & Zoller Coal & Mining Co. recently completed construction of two slopes at Mine 3 near Zeigler , Ill . The slopes are in the Big Muddy River Valley , and construction was particularly difficult because the strata from the surface to a depth of 70 feet comprise water saturated sandy clay and sand . Many mining companies have similar shaft- and slope - sinking problems , and because these slopes were satisfactorily completed and now are in use the methods followed during construction are described in this information circular . It is believed that other companies with similar problems . will benefit by adopting the methods followed at Mine 3 .

Apr 1, 1949

By Earl R. Maize

This is the first of a series of reports dealing with development of a method of strengthening bituminous-coal-mine roof. Later reports will describe the progress made with injecting high cohesive and adhesive bonding agents into bedding planes and mine tests of roof strata strengthened by the bonds formed. The concept of strengthening roof strata in coal mines by inserting steel rods in the form of bolts has been widely accepted by the coal industry. The benefits of increased production and safety derived from this type of roof support has more than justified the increased cost of roof bolting. However, not all coal-mine roof structure is amenable to this type of support, and failures occur owing to the heterogeneity and variable character of mine-roof strata.3/

Jan 1, 1957

By Kenneth L. Rubow, Virgil A. Marple, Bruce K. Cantrell

"In a cooperative study by the University of Minnesota and the U.S. Bureau of Mines, diesel exhaust and mineral dust concentrations have been measured for aerosols generated in the laboratory and in five underground coal mines. Three mines utilized diesel-powered haulage equipment and two used all-electric equipment. Two source apportionment techniques have been applied to differentiate between the mineral dust and diesel exhaust aerosol concentrations measured. The first technique, using a micro-orifice, uniform deposit impactor (MOUDI) for size selective sampling, is based on modeling aerosol size and the premise that the diesel exhaust portion of the aerosol is predominantly submicron and the mineral dust portion is mostly greater that one micrometer in size. The second technique, Chemical Mass Balance (CMB) modeling, was used to referee the analysis of diesel exhaust and mineral dust aerosol concentrations from the size selective sampling results.The MOUDI size distribution data were modeled to obtain parameters describing the fine and course fractions of the sampled aerosol and to estimate the contributions to each mode from both mineral dust and diesel exhaust aerosol sources. The results showed the size distribution of the mixed aerosols exhibited two definite modes with the minimum between the modes occurring at 0.8 µm. Less than 5 pct of the coal mine diesel aerosol was found in the coarse size fraction. CMB analysis confirms the original premise for using aerosol size to separate diesel exhaust and mineral dust aerosol during sampling.Based on the results from the size selective sampling, a personal diesel aerosol sampler has been developed for measuring diesel aerosol mass concentrations. Th.is sampler uses an inertial impactor to size separate the respirable aerosol at 0.8 µm. All material less than 0.8 µm is collected on an after filter for subsequent gravimetric analysis."

Jan 1, 1990

By J. W. Thompson

"The recent discovery and exploitation of petroleum territory have resulted in the enactment of new petroleum laws in most of the South American Republics. The activities in the discovery of these new fields were engendered by the knowledge of the fact that present producing fields must within well defined periods be exhausted. Oil operators were willing to take the initial steps in exploitation in the absence of legislation that applied strictly to petroleum operations. The enactment of modern legislation in many of these Republics encouraging and protect¬ing exploitations may cause tremendous oil activities in these countries, and the results may be comparable with the magnitude of the undertakings and the prestige of the companies now entering this territory.These, oil fields are admirably located for convenient distribution of petroleum by water to all the Nations using oil as fuel for shipping and industrial concerns. The oil markets of the western coast of South America will derive immense benefits from the Panama Canal. This navigation route brings these markets into direct ocean shipment with the Atlantic coasts of the Western and Eastern Hemispheres.One deterrent to oil production in the Republics of South America is the want of inland. transportation facilities, but the recent laws of these Republics without exception provide for acquiring rights of way for pipe lines and other modes of transportation; and doubtless the great interests and. syndicates already operating in these regions will, as production increases, provide ample pipe line transportation sufficient to convey to the coast the oil produced. It way be assumed, from the legal guarantees afforded, and from operating equipment and machinery that are now being concentrated that refineries will be erected at shipping points for the purpose of making these petroleum products accessible to the world."

May 1, 1921

By Byron M. Bird

"The prevailing practice of washing unsized coal, 1/2-inch and finer, to 1/8-inch and finer, on a table is subject to certain limitations which are commonly overlooked. In some instances good results are obtained by this method, but often the opposite is true and the efficiency of the washing operation is low. Although the separation taking place on a concentrating table is not fully understood, the actual distribution of particles of various sizes and specific gravities was determined a number of years ago by ore-dressing investigators. Hence this paper consists of an analysis of an old problem by new methods. The experimental data on which the discussion is based were obtained in the course of coal-washing investigations conducted by the U. S. Bureau of Mines at the Northwest Experiment Station in cooperation with the University of Washington and with certain coal operator: of that State.Experimental WorkThe general method of study has been to take a large number of zonal products from the table, and separate them according to specific gravity and size into their component parts. The table used is one of the standard commercial sizes with a diagonal deck. The coal to be washed is split into representative portions, which are stored in separate bins. One portion is used for ""timing as"" the table; the products are collected continuously in the same turned to the feed bin, and thus a closed circuit is completed. When the despite conditions on the table are obtained, coal is fed from one of the re. After the table is operating smoothly the entire product is minute; such a sample is sufficiently large to represent accurately the work of the table and at the same time to minimize the effect of beginning at the end next to the head motion, separate samples are made for each foot along the edge of the deck."

Jun 1, 1926

By H. L. Gibbs

Many factors contributed to the decision to build a radiochemical laboratory at the Salt Lake City Metallurgy Research Center to investigate the application of radioactive isotopes and chemical compounds in extractive metallurgy. These reasons included the notable success achieved in biological sciences with radioisotopes, the development of reliable instruments and methods for identifying the isotopes and measuring their activities, and the commercial availability of radioisotopes in a variety of forms and known activities. The paramount reason, however, was the realization that better methods were needed for guiding and quantifying research to resolve the complex extractive metallurgy problems under study at the Research Center. This is the first of a series of reports describing the application of radioisotopes and radioactivity techniques in extractive metallurgy. The report includes a discussion of licensing and safety requirements, a general description of the laboratory and the methods used, a definition of the nature and scope of the research program, and a synopsis of the more important problems studied. Subsequent reports will concern radioactive techniques for solving specific problems in mineral dressing, hydrometallurgy, and pyrometallurgy.

Jan 1, 1960

By W. H. Forbes

The prevention of accidents from falls of roof and coal requires a considerable amount of personal judgment , for conditions are different even in adjoining working places in the same mine , and conditions may change from hour to hour even in the same working place as the coal is shot down and loaded . Experience has shown that many men can not or do not exercise enough care to protect themselves from injuries ; moreover , where the foremen have been made directly responsible for the safety of the men under them , accidents from falls of roof and coal have , in many instances , been reduced as much as 50 per cent . There is now no question that careful , constant , and intensive supervision is essential in preventing acci- { dents and more especially accidents of this class . Falls of roof and of coal account for approximately 50 per cent of all coal mine accidents and annually result in the death of approximately 1,000 men and cause lost - time injury to approximately 50,000 men . These and other accidents are recurring with little or no diminution , usually not because of the lack of knowledge of safe and dangerous practices , or of the technique of safety , but largely because of the lukewarm interest of major executives in safety or the failure of mine officials to formulate and to enforce common - sense rules and regulations . When failure is the outcome of a sincere attempt of the managing officials to teach safety to the miner , the fault may usually be attributed to misguided effort . Various solutions for the problem of eliminating accidents from falls of roof or coal have been suggested , some of which are : Standard system of timbering for the specified mining districts ; departure from the room-and - pillar system to a more concentrated system of mining ; more intensive supervision - that is , 1 section foreman for every 25 loaders instead of 1 section foreman for 75 , 80 , or even more loaders the practice in most mining districts . - However , investigations conducted by the writer at numerous mines operated by a number of mining companies in several districts show that employees and officials alike are inclined to work under loose and unsupported roof , relying solely on the " drummy " sound and on their judgment and experience as to whether the roof will stay in place for one hour or for several hours . With but few exceptions , men who had been injured by falls of roof or ccal or were found working under loose and unsupported roof , admitted that they knew of the possibly unsafe condition , but it was their opinion that the roof or coal was not loose enough to fall for some time .

May 1, 1931

By Lloyd A. Morley

This report abstracts project work performed under USBM Grant GO155003 during the period 4 November 1975 to 3 November 1976. The research was funded, as a continuance of previous support from USBM Grants GO133077 and G0155003, to gain further knowledge in mine electrical system safety. Five reports have been separately produced, all under the grant title, "Coal Mine Electrical System Evaluation," and are as follows: 1. Volume I - Continuous Monitoring, 2. Volume II - Transient Analysis, 3. Volume III - Shielded Cables, 4. Volume IV - Computer Modeling, and 5. Volume V - Battery and Battery-charging Safety. Abstracts of these comprise the balance of this document with one exception. The task ?d-c offsett currents," does not fall under the scope of the other report volumes and, further, the material to be presented does not justify a separate report. Hence, this subject concludes the Executive Summary.

Jan 1, 1977

By By Staff

"This publication summarizes, for potential contractors and all other interested parties, the research, development, and demonstration of in-house and contract projects programmed by the Bureau of Mines for fiscal year 1982(October 1, 1981-September 30, 1982) under its Minerals Health and Safety Technology program. The objective of these projects is to provide an ordered and sequenced series of advance toward the Bureau's overall goal of providing the systems technology required to create a more healthful and safer working environment for the Nation's mining and minerals processing workersINTRODUCTION The Bureau of Mines conducts a balanced, continuing in-house research and development program to accelerate systematic improvements in health and safety conditions in U.S. mines. Part I of this report outlines the Bureau's present in-house effort to all interested parties; in particular, potential contractors can refer to it when submitting USP's (unsolicited proposals), thus avoiding proposing research that duplicates work being performed by the Bureau.It is the policy of the Bureau of Mines to utilize as fully as possible the capabilities of the private sector in minerals research, and to that endPart II of this report outlines the Bureau's current projected contract research needs.The projects presented were planned at the beginning of the fiscal year and are subject to change based on emerging priorities and availability of funds. Contingencies may require that a significant portion of the program be deferred into fiscal year 1983 (FY 83) or beyond. It is important to realize that since this is a summary document, the project descriptions related to a design, fabrications, and demonstration effort do not necessarily imply total package procurement."

Jan 1, 1982