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By R. V. Ramani, R. Stefanko, G. W. Luxbacher

1 9 THIS IS A DIGITAL COMPUTER SIMULATION OF THE VENTILATION SYSTEM OF A MINE LOCATED IN WASHINGTON COUNTY; PENNSYLVANIA. THE VENTILATION SURVEY ON WHICH THIS SIMULATION IS BASED WAS RUN FROM OCT. 27-30 AND ON NOV. 2;1976 IN THE ACTIVE PORTION OF THE MINE INBY COMBS SHAFT AND THE INACTIVE PORTION AROUND AND INBY DONAHOO SHAFT. FOLLOW-UP SURVEYS WERE THEN RUN ON FEB. 18 AND FROM MARCH 7-11;1977 TO INCLUDE THE MAIN HAULAGE SYSTEM OUTBY THE ACTIVE AREAS 0F THE MINE. ALL SURVEY DATA WAS NORMALIZED TO A STANDARD DENSITY OF 0.075 POUNDS/CU.FT. PRIOR TO THE CALCULATION OF INPUT PARAMETERS FOR THIS SIMULATION.

Jan 1, 1977

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

1 11 THIS IS A DIGITAL COMPUTER SIMULATION OF THE VENTILATION SYSTEM OF A MINE LOCATED IN WASHINGTON COUNTY, PENNSYLVANIA. THE VENTILATION SURVEY ON WHICH THIS SIMULATION IS BASED WAS RUN FROM OCT. 27-30 AND ON NOV. 2, 1976 IN THE ACTIVE PORTION OF THE MINE INBY COMBS SHAFT AND THE INACTIVE PORTION AFCUND AND INBY DONAHOO SHAFT. FOLLOW-UP SURVEYS WERE THEN RUN ON FEB. 18 AND FROM MARCH 7-11, 1977 TO INCLUDE THE MAIN HAULAGE SYSTEM OUTBY THE ACTIVE AREAS OF THE MINE. ALL SURVEY DATA WAS NORMALIZED TO A STANDARD DENSITY OF 0.075 POUNDS/CU.FT. PRIOR TO THE CALCULATION OF INPUT PARAMETERS FOR THIS SIMULATION.

Jan 1, 1977

By Thomas P. Mucho, Dennis Dolinar, Christopher Mark

During the 1990s, the former U.S. Bureau of Mines conducted a number of field studies in which the performance of different types of roof bolts were evaluated in different geologic environments. The studies used a standard suite of measurements, including multipoint extensometers, strain-gauged roof bolts, and roof bolt load cells. The sites were chosen to investigate the effect of a variety of parameters, including installed tension, bolt capacity, grout annulus, and horizontal stress orientation. Although not fully successful, the measurements provided valuable insights into each of these issues. They also showed that instrumentation and monitoring have important advantages over observational methods for comparing the performance of different roof bolting systems.

Jan 10, 2000

By D. Debasis, Christopher Mark, Gregory M. Molinda

The stability of any underground opening is, in large part, a function of the strength of the rock mass which surrounds it. The Coal Mine Roof Rating (CMRR) has been developed to quantify the defects in the rock mass and compile a strength value which can be used for engineering design. The CMRR has been applied to a number of ground stability problems, including chain pillar design, roof bolt selection, hazard assessment, intersection design, and numerical modeling. The CMRR procedure and some of these applications are described in this paper. The CMRR will soon be available in a Visual Basic computer program, allowing easy integration into exploration programs and standard roof fall assessments.

By J. W. Miller

An investigation was begun by the Bureau of Mines in 1948 to determine the preparation characteristics of American coals. Results of the investigation were planned to be reported on a county basis and from the data developed to determine: 1. Which coals either as mined or after beneficiation by conventional preparation are chemically suitable under present standards for producing metallurgical coke. 2. Which coals require special and more intensive treatment in preparation than is now practiced. 3. Which coals cannot be considered potential sources of metallurgical coke, regardless of preparation by present-day methods. This report is one in this county series that describes the preparation characteristics of the coals of Lee County, Va.

Jan 1, 1957

By T. R. Jolley

An investigation was begun by the Bureau of Mines in 1948 to determine the preparation characteristics of American coals. Results of the investigation were planned to be reported on a county basis and, from the data developed, to determine: I. Which coals either as mined or after beneficiation by conventional preparation are chemically suitable under present standards for producing metallurgical coke. 2. Which coals require special and more intensive treatment in preparation than is now practiced. 3. Which coals cannot be considered potential sources of metallurgical coke, regardless of preparation by present-day methods. This report is one in the county series that describes the preparation characteristics of the coals of Bell County, Ky.

Jan 1, 1957

By Rustu S. Kalyoncu

Nonoxide ceramics with improved high-temperature properties could substitute for high-temperature alloys and reduce toe Nation's dependence on imports of Cr, Co, Ni, and Mn. To meet this objective, the Bureau of Mines conducted research to synthesize u1trafine reactive boron nitride (BN) powders BN powders were prepared at temperatures ranging from -75? to 750? C. Low-temperature reactions (-75? to 200? C) between boron halides and N compounds led to formation of e1emento-organic compounds that were thermally decomposed to u1trafine (approximately 100-to 150-A particle size) reactive BN powders. BN powders were also prepared through the reaction of a 10w-me1tinginorganic B compound (boric acid, borax) with an organic N compound (carbimide and thiocarbimide) in N2 and/or ammonia (NH3) atmospheres at temperatures between 500? and 750? C.

Jan 1, 1986

By Ronald A. Munson

Samples of the naturally occurring zeolites phillipsite, clinoptilolite, erionite, and chabazite have been surveyed for their gas adsorption, ion exchange, and other characteristics. Chabazite and erionite, which are generally more stable, also have higher methane adsorption capacities than do the other natural zeolites. Both natural erionite and natural chabazite are classified as small-port zeolites on the basis of their inability to adsorb chlorotrifluoromethane. In the range of 8 to 100 mesh, the adsorptive capac-ity of natural zeolites is improved only slightly by a decrease in particle size. The capacity of natural clinoptilolite to adsorb methane is increased by cation replacement by the hydrogen ion and decreased by exchange with calcium ion. Natural phillipsite, which is easily decomposed by heat, adsorbed methane to a limited extent.

Jan 1, 1973

By Robert C. Johnson

Domestic byproduct fluorine (in fluosilicic acid) availability at various price levels of aluminum fluoride were determined and a contingency availability curve developed. The supply of byproduct fluosilicic acid is restricted in amount to certain geographic regions, where plants processing phosphate rock are located, and the byproduct can be collected. The maximum possible U.S. annual supply, based on potential plant capacities, is 373,400 tons of fluosilicic acid containing 295,400 tons of fluorine. Based on inputs of 5, la, 25, 50, and 100 thousand tons per year, five levels of producing aluminum fluoride from fluosilicic acid (100 percent) were costed. Based on a 12-percent discounted cash flow rate, including the cost of salvaging the fluosilicic acid, the calculated selling price of aluminum fluoride ranged from $233 per ton to $448 per ton. At the higher price, 98 percent of the potential supply of byproduct fluosilicic acid could be used profitably; at the lower price only 46 percent could be used profitably.

Jan 1, 1973

By M. C. Malamphy

A general description of the activities and results of bauxite investi-gation by the Bureau of Mines at its bauxite project in Saline and Pulaski Counties, Ark., has been given in Report of Investigations 4251. The factual data obtained during the project are reported in a series of Reports of Investigation beginning with No. 4251, of which this is the sixteenth. The data are accompanied by maps showing the location of holes drilled and the deposits developed. Each area upon which work was done is reported by half townships. Each bauxite deposit investigated was assigned a name and a number for ready reference and identification, and its location and name are shown on the appropriate half-township map. The description of each half township is followed by a description of each deposit developed in that half township. The 14 half-township maps and 77 detail maps of the bauxite deposits in this series of reports give the locations and numbers of all the holes drilled on the project, except the deep holes drilled to test the geophysical anomalies. The locations of the latter holes show on figure 13 in volume 1. The descriptions of the deposits developed are followed by complete detailed logs of the drill holes. Many of the widely spaced exploratory holes did not discover bauxite of minable thickness and grade. The pertinent information obtained from the widely spaced exploratory drill holes has been summarized and tabulated, and a table for each half township is given with the discussion covering that area.

Jan 1, 1948

By D. B. Gawthrop, A. Taylor, G. St. J. Ferrott

"This paper presents data obtained as part of an investigation of the explosive properties of ammonium nitrate. During the course of the work: it was found desirable to investigate the sensitizing action of nitrostarch in mixtures of ammonium nitrate containing low percentages of this material. Data were derived as to the sensitivity to decomposition by heat and the completeness of detonation and,of detonation of straight ammonium nitrate, as compared with ammonium nitrate-nitrostrarch mixtures containing 1 to 10 per cent of nitrostarch.The ammonium nitrate was a sample of coated material obtained from the salvage of amatol shells. Its analysis was as follows:"

Feb 1, 1930

By GEORGE S. POPE

The purchase of coal by the Government under specifications depending on the heating value of the coal, its content of ash and of moisture, and other considerations, rather than upon the reputation or trade name of the coal, was based on the fuel investigations begun by the Technologic Branch of the United States Geological Survey in 1904. The plan was first adopted by the Treasury Department in 1906. Since then the plan, variously modified in form but the same in principle, has been gradually adopted by other departments until at present of the coal used by the Government, the total value of which approximates $8,000,000 annually, more than half is purchased under specifications. The Government publications dealing with the adoption by the Government of the specification plan, the number of contracts awarded on that basis, and the quality of the coal delivered under such contracts in the several fiscal years covered by the reports are given in publications listed at the end of this bulletin. Under the authority of acts of Congress making appropriations for analyzing and testing fuels belonging to or for the use of the United States Government, a laboratory is maintained at the headquarters of the Bureau of Mines, Washington, D. C., where samples represent- ing deliveries of coal purchased under specifications for Government use are analyzed and tested. At this laboratory more than 1,200 samples have been analyzed and tested in one month. With the complete equipment and the efficient force employed, the analytical work has been so perfected that the analyses and heating-value tests of the samples received are as accurate as may be reasonably expected in laboratory work of this nature. One of the serious drawbacks to the general adoption of the speci- fication method for the purchase of coal is the difficulty of obtaining at reasonable cost samples of coal that can be considered fairly repre- sentative of the commercial product delivered in wagons, railroad

Jan 1, 1913

Although the technology involved in removing material from below the earth's surface has a long history, communication systems in underground workings are relatively new to the industry. Communication equipment did not begin appearing in underground mines until the early 1900's. Figure 1-1 shows a miner using a Western Electric standard telephone set for underground mines in 1913. These early phones were essentially the same as those used aboveground, except that they were enclosed in cast-iron boxes as protection against moisture, acid fumes, and gases. In the 1950's, the Chesapeake and Potomac Telephone Co. of West Virginia introduced a telephone set for use in explosive atmospheres that was designed around the philosophy of explosion containment. To contain an explosion within the telephone set required a 39-pound casing, which greatly limited portability. [ ] Both of these telephone sets required "pipe" or conduit, not a very practical item for a 100-squaremile coal mine. A common thread prevalent in the first 40 years of design and development is that the primary effort was placed on the telephone set. In the early 19701s, as work began on the design of modern communication systems for use in underground mine environments, the following requirements were established: 1. Must meet intrinsic safety standards .--This applies not only to coal mines, but to other explosive environments. 2. Must be compatible with the environment.--The system must with- stand dust, moisture, and corrosive conditions. 3. Must be rugged in structure.-- The system must withstand maintenance by 10-inch pliers and 4-pound hammers, as well as impact from a falling piece of roof. 4. Must be size-flexible.--Whatever is built must be sized for the small operator as well as the large companies. 5. Must be a total system in design.--The system must be intrinsically safe, including cable, power supply, and station set. 6. Must work with present telephone system.--The system should be compatible with aboveground communications already in place; it should not be the single cause of change in aboveground communications. 7. Value-added pricing.--The system should be reasonably priced so that savings created by its introduction will more than offset the installation cost.

Jan 1, 1984

By Herbert R. Babitzke

The purpose of this investigation was to optimize the high-temperature properties of columbium and tantalum. Columbium and tantalum were combined with selected alloying elements to achieve solid solution and dispersion strengthening. Fifty-six alloys were evaluated to determine their formability, hardness, strength at elevated temperatures, and oxidation resistance. The following six alloys showed high-temperature strength: [Cb-15Hf-5W-2Zr-4Al-4Ti-2N Cb-15Hf -5W-5Zr Cb-15.3Ti-4.1Zr-13.7Hf Ta-20Hf-4Al Ta-30Hf-4Al Ta-20Hf-5W-4Al] At 1,200° C, the columbium alloys had strength values of 40,000 psi or greater, and the tantalum alloys had strength values from 50,000 to 58,000 psi. For a 2-hour test period at 1,000° C, weight gains of only 9 and 8 mg/cm2, respectively, were observed on oxidation testing of two alloys, Cb-15Hf-5W-2Zr-4Al-4Ti-2N and Ta-20Hf-5W-4Al.

Jan 1, 1968

By John C. Machisak

Statistical data on injuries in the metal and nonmetal industry of the United States first became available to the Bureau of Mines by collecting reports from the operators for the calendar year 1911. Since then reports have been collected annually. The present bulletin, covering the calendar year 1954, is the 31st publication (1933-34 was published as Bulletin 398) containing statistical data on injuries at metal and nonmetal mines and related plants, and it 1s the first such bulletin to be published since 1942. The last publication was Bulletin 461, Metal and Nonmetal-Mine Accidents in the United States, 1942. The unpublished statistics for 1943-53 may be found in the Appendix of this bulletin. The Bureau of Mines is authorized to collect data on injuries and related employment at metal and nonmetal mines, but there is no Federal law that compels operators to submit such information. Therefore, all materials submitted are voluntary responses to the Bureau's requests for information. The figures presented herein may not be complete for the entire industry, nevertheless, every effort has been made to make them so, and the data given are believed to be representative of the hazards to which metal and nonmetal workers are exposed. Moreover, the figures are comparable as between States-which is significant in view of the lack of uniformity among the States as regards classes of plants covered by State laws, classes of injuries covered by State reports, and other factors that tend to make it impracticable or impossible to compare the injury experience of one State with that of another or comprehend the relative importance of the various causes of injuries in the industry as a whole.

Jan 1, 1957

By Richard F. Link

The principal procedures for the statistical analysis of gold assay and other trace-element data depend on applying either the normal frequency distribution or the lognormal frequency distribution. The consequences of applying both methods are examined through reference to example data from United States and South African gold mines. It is concluded that for estimation of average grades, except for certain data with a very high coefficient of variation (ratio of standard deviation to mean), use of the lognormal distribution is ordinarily undesirable because bias may be introduced and little efficiency can be gained. However, if biased average grades can be tolerated, as in the examination of data from surveys in exploration geochemistry, use of the log-normal distribution may be desirable. Various statistical analyses are detailed, and the tables presented to implement the analyses are more complete than those previously published.

Jan 1, 1971

By William W. Adams

Progress made by the quarrying and related industries of the United States during 1939 included increases in the number of men employed and the number of man-hours worked and reductions in the death and injury rates per million man-hours of exposure to risk. Forty-seven States reported quarries in operation; in each of 26 States the industry employed 1,000 or more men. Of these 26 States, 16 reported lower accident rates than in 1938. Among the operations of various types for which separate figures are published in this bulletin, the limestone, lime, and cement groups reported lower accident rates. During 1939, 79,449 men were employed in the quarrying industries. The period of operation of the plants averaged 236 clays per employee, with a total working time that equaled nearly 144 million man-hours. Accidents at the plants resulted in 48 deaths and 5,204 disabling injuries among the workers. Expressed as frequency rates, the accidents represented 0.33 fatality and 36.18 injuries for each million man-hours of work performed during the year. The major cause of fatal accidents inside the quarries was falls or slides of rock or overburden; nine deaths were reported from this cause. Four men were killed by explosives and four by falls of persons. Nonfatal injuries inside the quarries were clue chiefly to handling materials; about one-sixth of the total number at all operations in connection with quarries and related plants were in this class. Flying objects also caused numerous injuries, although only about one-half as many as did handling materials. Next in numerical importance were injuries from falls of persons. Then followed accidents caused by falls or slides of rock or overburden and accidents caused by machinery.

Jan 1, 1941

By M. E. Tyrrell

The purpose of the work leading to this report was two-fold: (1) To determine the properties of cemented tungsten carbide modified by the addition of one, two, and five percent of titanium diboride, and (2) to compare the properties of these mixtures when sintered, hot-pressed, and flash-welded (resistance-sintered). Minor additions of titanium diboride to mixtures of 94 percent WC and 6 percent Co decrease mechanical strength but increase oxidation resistance in proportion to the amount of the addition. One percent of titanium diboride increased the hardness by 2 Rockwell A units. Hot-pressing produced compacts with the highest density and the best mechanical strength, but losses of cobalt were high and grain growth was pronounced.

Jan 1, 1962

By Francis R. Redfern

Newton's method of solving a nonlinear equation is employed to develop a least-squares acoustic emission source location method in which the spatial residuals of the location equations are minimized. These residuals, related to the distances from the least-squares source location perpendicular to the surfaces described by the location equations, permit location error to be estimated to first order along the spatial axes. The solutions obtained by this method are the best spatial solutions to the location equations in the least-squares sense. Also presented is a procedure by which the geometrical control of a transducer array can be evaluated using the rate of change of source location with fractional velocity change.

Jan 1, 1982

By E. D. Gardner

An explosion occurred in a high-pressure compressed-air line in October, 1930, at an Arizona copper mine. The explosion was unusual, and nothing had teor. noted by the plant operators to indicate the possibility of such an occurrence. It is necessar The air is The mining company uses compressed-air locomotives to haul about 4,500 tons of ore per day from the stopos to the pockets at two hoisting shafts. The ore cars hold five tons each, and are pulled in trains of 30 cars. to charge the locomotive with compressed air at both ends of the trip. conveyed from the compressors at the surface to the distributing points unier roun in special high-pressure four inch steel pipe that was tested to withstand 2500 pounds per square inch before being installed. The air is delivered to the loco- motives at a pressure of 1000 pounds per square inch. There are no receivers in the system. The air for running the locomotives is compressed by one three-stage and two four-stage compressors which have capacities of 600 and 300 cubic feet per minute, respectively. These machines are operated by electric power, and are in an end of the main compressor building in which air is compressed to supply the air drills in the mine. Whenever the demand decreases, as at the noon hour, one or more of the Compressors are shut down. On this particular occasion, at the end of the noon hour, one of the operators was approaching the high-pressure compressors to start the two smaller machines that were not running, when the explosion took place under the floor a few fost ahead of him. The man was mocked down and received some superficial cuts and bruises, but was not seriously injured. The floor was torn , the side of the building blown out, and holes imo cited in the roof some twenty feet above. The explosion was immediately followed by a fire which was quickly put out by the plant operators with hand fire extinguishers. At the time of the explosion the 600 cubic foot compressor was running alone, and the pressure in the system at the machine registered 1040 pounds por square inch. On examination it was found that two 6-fout sections of pipe, about tan feet apart, were completely ruptured into twisted fragments; the rest of the pipe line, apparently, was not injured. The destroyed sections were in that part of the pipe near the large compressor and above the connection from the two smaller machines. It is not definitely mom what caused the explosion. Explosions in other compressed-air systems have taken place, and, although of rare occurrence, have caused loss of life. Such explosions are not confined to high-pressure installations and several have occurred at plants compressing air te one hundred pounds per square inch, or less. plosions of this nature are not to be confused with the rupturing of compressor cylinders from excessive air pressure caused by the discharge valve being closed.

Feb 1, 1921