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By Raymond M. Stateham

The Bureau of Mines used portable infrared scanners to examine the surface of pillars and faces in the Somerset mine near Somerset, Colo. Zones of temperature buildup, indicative of potential combustion, were detected with the scanners; their existence was verified by temperature measurements with conventional instrumentation. Temperatures of 32° to 6° C were measured on surfaces with normal temperatures of 26° to 35° C. The infrared instruments and techniques appeared to offer a rapid and efficient method for locating potential trouble spots in mines susceptible to fires caused by spontaneous combustion.

Jan 1, 1974

By Douglas C. Corner

This is the first of a series of papers dealing with modern tunnel-driving methods, compiled in accordance with an outline prepared by engineers of the United States Bureau of Mines and to be published in a series of information circulars by the bureau. This series will supplement a similar and earlier series of papers dealing with mining methods and costs. ACKNOWLEDGMENTS The author desires to express hiss appreciation, of the assistance of A. C. Dennis, manager for the West Construction Co. Contractors, and Franc: E. Winsor, chief engineer for the Boston Metropolitan District mater Supply Commission who furnished much of the data and detailed description of operation appearing in the following pages. C. F, Jackson, mining engineer, United States Bureau of Mines, collaborated in the preparation and arrangement of the text.

Jan 1, 1931

By D. H. Carlson, J. H. Johnson

"The U.S. Bureau of Mines and Michigan Technological University (MTU) are collaborating to develop an apparatus for measuring diesel tailpipe emissions in underground mines. A tailpipe emissions measurement apparatus (EMA) is described that dilutes diesel exhaust and measures the concentrations of diesel particulate matter (DPM), CO, CO2, NO, and NO2 at known dilution ratios.The EMA was evaluated by side-by-side comparison of its measurements with those by laboratory grade instruments. Concentrations of CO and C02 measured by the EMA were usually within ± 14 pct of concentrations measured by laboratory-grade instruments for CO and ±20 pct for C02• EMA measured DPM concentrations were, on average, 29 pct lower than those measured by laboratory-grade instruments, with the differences being fairly consistent. The CO and C02 differences are related to the method of calculating the EMA's dilution ratio, and the difference in DPM concentrations is attributed to thermophoretic and/or condensation losses related to the EMA's unheated sample probe. Preliminary analysis of data obtained with a heated sampling probe and modifications in the sampling procedures have indicated reduced variability in DPM and in the calculated dilution ratios."

Mar 1, 1992

By L. C. IlsLey

The theory and practice followed by the Bureau of Mines in investigating electrical equipment4/ made for service in gassy mines are of particular interest not only to manufacturers but also to those organizations that deal with safety anal inspection at the mines. This publication purposes to discuss the theory upon which tests of equipment in explosive atmospheres are based and to consider inspection and other matters pertaining to investigations made by the Bureau in ascertaining whether a machine merits approval. The material in this report is taken from an earlier bulletin,5/ which is row out of print, and has been revised and brought up to date to make the information again available to manufacturers, inspectors, and others interested in the development of safe equipment.

Jan 1, 1954

By Keith L. Harris

Real gross national product3 (GNP) grew at a seasonally adjusted annual rate of 4.2% in the fourth quarter compared with a revised 4.3% rate in the third quarter, according to the most recent estimates released by the U.S. Department of Commerce (table 1). Expanding inventories, Government purchases of goods and services, residential fixed investment, and a narrowing of the trade deficit fueled the growth. Significantly reduced consumer demand led to the heavy inventory growth. Almost half of the buildup in inventories consisted of automobiles because consumers reduced purchases when Detroit ceased most incentive programs in late summer. Reduced consumer demand also affected imports, however, and the narrowing of the trade deficit resumed after widening in the third quarter. Nonresi- [ ] dential fixed investment also declined after a strong gain in the third quarter. On a year-to-year basis, the economy grew at an inflation-adjusted rate of 2.9%, the same as that of 1986. However, on a fourth-quarter-to-fourth-quarter basis, the real growth reached 3.8%, the highest growth since 19M, and exceeded the Reagan Administration's estimate of 3.4%. Rising merchandise exports accounted for about one-third of the growth in GNP for all of 1987 and are expected to continue to grow as domestic manufactures benefit from the lower value of the dollar vis-a-vis other major trading country currencies. Consumer demand became a less important factor of economic growth, but employment continued to grow (table 2), and civilian unemployment declined by 0.9 percentage points (December to December) as the industrial sector geared up to increase exports. Inflation, as measured by the fixed-weighted GNP price index, remained low at 3.4%.

Jan 1, 1988

By K. M. Connor, O&apos

Variations in overburden geology must be considered in applying subsidence prediction methodologies developed by the U.S. Bureau of Mines (USBM). To characterize rock mass overlying high-extraction coal mines, the USBM utilizes a computer spreadsheet program and modified Rock Mass Rating (RMR) system. The spreadsheet calculates an RMR based on a bed's engineering properties determined from core logs and laboratory tests. An in situ deformation modulus and a bending stiffness are computed for each bed. Stiffness-versus-depth plots identify groups of beds with similar stiffness. Large variations in stiffness between adjacent beds are considered significant horizontal discontinuities where slip is likely. Time domain reflectometry (TDR) is used to verify this hypothesis by measuring shear displacement along such discontinuities. A model of the overburden is built by assuming that a near-surface laminated beam exists above a transition zone in which large plastic slip occurs along horizontal discontinuities. Increasingly thicker groups of beds are modeled to determine the most probable beam thickness based on a comparison with measured deflection profiles. The inverse of maximum beam deflection is an index parameter known as "bridging potential," a single value that incorporates both overburden geology and mine geometry.

Jan 1, 2010

By D. Harrington

Approximately 2,000 persons are killed annually in the coal mines of the United States. There is no question that this number is at least double and probably treble what it should be and by all means the least excusable of the fatalities are those caused by explosions and fires. Fatalities from explo- sions and fires in coal mines are almost invariably caused by carelessness or negligence. Table 1 indicates that the fiscal year ending June 30, 1931, ras by no means a satisfactory one as regaris either the number of explosions or the number of persons killed by them. This tabulation lists all ignitions to which the attention of the personnel of the safety division was called and in- cludes not only major disasters, but also explosions in which fewer than five were killed, as well as several explosions from which no fatalities resulted. It will be noticed that last year there were 26 explosions in mines in 10 States of the United States, resulting in 217 deaths. In the previous year there were 34 explosions with a death list of 199, and in the year before there were 38 explosions with a death list of 139. Hence, the past fiscal year had distinctly a poorer record of fatalities from mine explosions than either of the two previous years. Of the 26 explosions in the past fiscal year, Pennsylvania had 7, West Virginic 4, New Mexico and Ohio 3 each, Alabama, Oklahoma and Washington 2 each, and California, Illinois and Indiana 1 each; the one in California was in a tunnel being driven for water purposes but giving off explosive gas (methane). In fatalities Ohio had the worst record with 38, Oklahoma came next with 45, then Indiane with 38, and Pennsylvania with 23; although Alabama had 2 ignitions and Washington 1, they caused no fatalities. Utch, Colorado, and Kentucky had no explosions reported by the safety division of the Bureau of Mines during the past fiscal year, but were on the list for the previous year, though in the case of Colorado there were no fatalities. On the other hand, Indiana and New Mexico, neither of rhich was charged with an explosion in the two previous years, were on the list for the past fiscal year; New Mexico had the bad record of three explosions, though fortunately with but a total of eight fatalities. Ohio reported 3 explosions to the safety division of the Bureau of Mines in the past fiscal year, 2 in the pre- vious year, and 3 in the year before that, or 8 in the past three fiscal years with 92 fatalities; all of these eight explosions were in open-light mines.

Dec 1, 1931

This Bureau of Mines report is devoted to descriptions of systems that provide in-mine wired telephone service. Although they may incorporate other features, each system described functions to allow one telephone to selectively access another telephone. Except for the paper on Conventional Telephone Equipment, the equipment described is newly developed and specifically designed to satisfy the requirements of underground mine communications.

Jan 1, 1977

By John C. Machisak

Injury data and experience, with related employment statistics, at coal mines in the United States for 1960 are presented in this publication under the following general sections: A General injury experience: Tables 1 to 6: Current data on number of injuries, decree of injury, frequency and severity rates, average severity, and related employment and production data by work location. B Selected injury experience: Tables 7 to 38: Current data on principal agencies of injuries, distribution of injuries by part of body injured, days of disability, extent of hand and machine loading, experience by employment and production groups, and various other operating factors and physical conditions related to the occurrence of injuries at the Nation?s coal mines.

Jan 1, 1962

By Gene Asai

The Bureau of Mines investigated the caustic extraction of alumina and soda from retorted dawsonite-bearing oil shale, as part of a program to devise technology for treating alternative domestic sources of alumina for the production of aluminum metal. Colorado oil shale yielding 13 pct oil (35 gal/ton) and containing 12 wt-pct dawsonite (representing about 4 pct extractable alumina) was retorted to obtain oil-free (spent) shale Spent shale was leached with dilute NaOH to determine the effect of particle size, retorting temperature, leaching variables, and storage conditions on extraction of alumina and soda and dissolution of impurities. Maximum alumina and soda extractions were obtained by promptly leaching minus 28-mesh spent shale, obtained by retorting raw shale at about 5000 C, with 0.5N NaOH. Under these conditions, dissolution of impurities such as Ca, Fe, Ti, and P was low. Leaching tests were made on spent shale stored for periods of up to 30 days at 0° to 42° C and at 0 to 100 pct relative humidity (RH). These tests indicated that significant reductions in alumina extraction would occur if spent shale were stored in ambient Colorado air under naturally fluctuating temperature and humidity.

Jan 1, 1983

By Leslie D. Marrus

This project and final report represent an effort to collect, analyze, and verify reliability and performance data on currently available medium -to-high seam models of continuous miners being used in underground coal mining. The analysis determined availability, mean time and tons between failures, amounts of down time associated with various failures, labor and part costs required to correct failures, and various indices of maintainability. Machine performance and reliability are discussed relative to cumulative tons (machine age) produced and production rates (machine loading). It was determined that performance can be significantly improved given preventive maintenance programs that will increase machine availability.

Jan 1, 1976

By H. M. Cooper

The determination of moisture in coal is an empirical test, because the time, temperature, and equipment are specified. The essential features of the equipment and details of the procedure are given in A.S.T.M. Designation: D271-44.:2. According to the specifications, the following features should be incorporated in the equipment used: 1. Oven must have uniform temperature in all parts. 2. Oven must be constructed with minimum of air space. 3. Oven must have means of changing the air two to four times per minute. 4. Air must be dried over sulfuric acid (sp. f-7. 1.84). The analytical procedures governing most of the nation's coal purchases are those given in A.S.T.M. Standards referred to above. These standards are general arid of such scope as to cover all ranks and types of coal. In cases where only the moisture is required, a faster method than the standard procedure is desired.

Jan 1, 1948

By GEORGE S. POPE

This bulletin is the third of a series a showing the results of ment purchases of coal according to specifications as to its quality and giving typical forms of proposals for supplying coal and general information relating to government coal purchases . Numerous calls for authentic information concerning the purchase of coal according to its heat value attest a growing interest in the subject. Many of the commodities of life have long been purchased according to specifications requiring chemical or physical tests , or both, to determine whether the material delivered meets the requirements , the price to be paid depending on the results of the tests . Until recent years coal consumers purchased coal merely on the statement of the dealer as to its quality , relying on his integrity and on the reputation of the mine or district from which the coal was obtained. It is surprising that the important question whether value was being received for the money expended was not sooner seriously considered . The purchase of coal by specification is an important step toward the conservation of our national mineral resources , for it results in an increased use of the lower grades of coal. The poorer coals find a market by competing with the better grades , not as to the price per ton but as to the cost of an equal number of heat units. This paper gives in detail the results of government purchases of coal for the fiscal year 1908–9 and the list of contracts with abstracts of specifications for the fiscal year 1909–10 , and summarizes the information on this subject obtained by the Survey. It is hoped that this information will promote a better understanding of the specification method of purchasing coal and furnish data valuable alike to coal dealers and coal consumers , so that equitable contracts can be more readily made.

Jan 1, 1910

This Bureau of Mines report is a compilation of information on computer models of mineral commodity markets in the Federal Government, The directory was compiled by the Analytic System Working Group of the Interagency Minerals Information Coordinating Committee to support the formulation of policies related to nonfuel minerals.

Jan 1, 1984

By W. L. Dare

This information circular is one of a series published by the Federal Bureau of Mines in which the methods and costs of producing uranium ore on the Colorado Plateau are discussed. This report describes the three largest company-operated uranium mines of Climax Uranium Co. - the G-1, the Mineral Joe, and the Frank No. 1. Climax Uranium Co., a subsidiary of American Metal Climax, Inc., was [corporated] May 11, 1950, just 2 years after establishment of the domestic uranium program by the Atomic Energy Commission. Twenty-five years earlier Arthur H. Bunker, now chairman of the board, American Metal Climax, Inc., organized and operated the U. S. Vanadium Co. at Rifle, Colo.3/ Soon after Climax Uranium Co. was organized, it entered into a contract with the Federal Government to build a uranium-vanadium processing mill in Grand Junction, Colo. Under the contract Climax leased from the Federal Government certain uranium-bearing lands that had been withdrawn from public entry in 1948. From Minerals, Engineering Co. on June 12, 1950, Climax acquired other uranium-vanadium properties on Calamity, Outlaw, and Monogram Mesas in Colorado and on Polar Mesa and in the Yellow Cat area of Utah. To house the milling equipment, Climax leased the old Grand Junction sugarmill building of the Holly Sugar Co. Milling facilities, based on a then new process developed for treating both uranium and vanadium, were completed, and the plant went into production in 1951.

Jan 1, 1959

By G. W. Elger

The Bureau of Mines investigated the conversion, at both laboratory and pilot plant scale, of a low-grade ilmenite to chlorination-grade feedstock that could substitute for imported rutile used to produce titanium tetrachloride. The concentrate was derived from the Tahawus, NY, lode deposit of ilmenite-magnetite in rock that contains anorthosite and gabbro. Charges of the ilmenite concentrate, containing 46.6 wt pct Ti02 blended with soda ash, were carbothermically reduced in an electric arc furnace, which separated most of the iron and left a high-titanium slag. However, the slag contained Ca, Mg, and Mn constituents that rendered the material unsuitable for continuous chlorination by causing plugging problems. After being ground and pelletized, the slag was reacted with S02 and air at 7000 to 9000 C, which selectively converted the harmful impurities to soluble compounds that were removed in a subsequent water or dilute HCI leach. In laboratory tests, the combined levels of harmful impurities were decreased from 5 to as low as 0.5 wt pct in leached slags. In pilot plant tests, leached slags sulfated at a rate of 10 lb/h averaged 85.5 wt pct Ti02 with pertinent impurity levels averaging 1.86 wt pct. The leached slag was successfully chlorinated in a laboratory fluidized-bed reactor at 9500 C to extract titanium as TiCI4.

Jan 1, 1986

By R. L. Bolmer

Driving long development raises probably is one of the most hazardous and expensive operations in underground mining. The safe handling of men and materials becomes more difficult and more time consuming in the higher sections of the raise. The efficient ventilation of these sections often is a major problem. This information circular describes a unique method by which Resurrection Mining Co, safely and efficiently completed a 622-foot vertical raise at its Irene shaft near Leadville, Colo. The method used by the company involved driving a raw, 6-foot-diameter ventilation raise and emergency escapeway, using a work cage that was suspended on a hoisting rope extended down a small-diameter drill hole. Although the method was new and experimental, the raise was completed in record time. Overall costs were less than they would have been with conventional methods. The company's initial experience suggested improvements both in design and operating technique that should prove of value to others who contemplate using the cage method of raising

Jan 1, 1958

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 James S. Browning

The Bureau of Mines conducted laboratory and small--scale continuous tests of weathered mica pegmatite ores from Hart County, Ga., to determine the technical feasibility of recovering commercial-grade mica concentrates by flotation. Two modifications of the Bureau-developed anionic-cationic method were used. In one method, sodium carbonate and calcium lignin sulfonate were used for pH control and quartz depression; this method yielded mica concentrates containing 98.5 percent mica with a recovery of 91.4 percent. In the other modification, lime and sodium silicate were used with the calcium lignin sulfonate; concentrates containing 98.9 percent mica with a recovery of 86 percent were obtained.

Jan 1, 1966

By D. Harrington

The prevention of accidents to children from blasting cans is of vital importance not only to everyone using commercial explosives but to the country at large. The manufacturers of explosives have realized this danger for years and have attempted to publicize the hazards of allowing blasting caps to fall into the hands of children. Unfortunately, many of tie users of explosives have failed to realize the danger or have ignored their responsibilities in the matter. Investigations of accidents to children from blasting caps (and scores of them occur annually) reveal that most of them are caused by blasting caps picked up or made easily accessible to the victims. The children who are blinded, maimed for life, or killed are in large part the innocent victims of the carelessness, thoughtlessness, or negligence of their elders, by whom blasting caps are left lying about, carried in the pockets, dropped or lost around blasting operations, stored away and forgotten, or left in places where trey can be found or are accessible to children. Many such accidents occur to children under 12 years of age, when they are still curious or inquisitive. One of the first reactions of a child upon finding a blasting cap is to investigate and "see" how it is made or how it "works." A blasting cap in itself, with one end open, invites a child to poke it with a nail, piece of wire, or some other object to see what is inside; or he may attempt to break it open with a rock or hammer. A lighted match could be thrust into the open end, and there are numerous other approaches, may of which can result in serious accidents.

Jan 1, 1944