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By H. B. Brunot

The United States Bureau of Mines under provisions of Schedule 2C4 issues approvals covering complete operating units such as loading machines, room hoists, and storage-battery locomotives. Certain manufacturers design and build entire machines. Other manufacturers purchase a part or all of the electrical accessories from manufacturers of electrical equipment and make up permissible units by assembling them. Before the assembler purchases electrical accessories for use in such contemplated units he may require certain information from the accessory manufacturer as to whether the particular accessories are suitable for assembly in his proposed permissible outfit. To aid accessory manufacturers in marketing their product, a provision was incorporated in Schedule 20 whereby tests might be made on individual accessories and reports rendered as to the suitability of a given accessory for use in permissible assemblies.

Jan 1, 1935

By Stephen E. Mosher, Suzanne D. Smith

Ground, air, and water vehicles can expose humans to substantial multi-axis vibration. Multiple input/multiple output relationships or models exist for estimating frequency response functions of linear systems1, 2. These relationships have been applied by some investigators to evaluate the effects of occupied seat vibration3, 4. Using a multiple input/single output model, this study investigated the effects of single- and combined-axis vibration in the fore-and-aft (X), lateral (Y), and vertical (Z) directions on vibration transmission to the human chest. Frequency response functions (transmissibilities) were estimated and compared for the back-on and back-off postures. Methods A rigid seat with seat back was mounted onto the Six Degree-of-Freedom Motion Simulator (SIXMODE). A flat acceleration vibration signal was generated between 2 and 40 Hz at 1.0 ms-2 rms in the single and combined X, Y, Z, XY, XZ, YZ, and XYZ axes. The signals were shifted in time so that the combined inputs were not fully correlated. Lightweight triaxial accelerometers were used to measure accelerations at the seat base (input) and at the bony manubrium of the chest (output). The maximum of nine frequency response functions (H(?)) or transmissibilities were estimated from the auto- and cross-spectra. The system transfer matrix for the XYZ inputs and chest Z output is [ ] where PxZ, PyZ, and PzZ are the cross-spectra between the three inputs at the seat base and the Z output at the chest, respectively, and Pxx, Pxy,…zz are the auto- and cross-spectra between the input signals (? not shown in Eq. 1). Equation 1 can be similarly written for the chest X and Y outputs. Matlab® was used to estimate the auto- and cross-spectral densities for calculating the transmissibilities, ordinary coherences (for single inputs), partial coherences, and multiple coherences. Results Figure 1 illustrates the major chest transmissibilities observed for the two postures. Vertical vibration showed a consistent influence on the chest X response (Chest X/Z), most likely causing chest pitch. Some chest Z responses were observed with X-axis inputs, but the results were variable and difficult to interpret. In general, other factors besides the known inputs did not affect the transmissibilities shown in Figure 1 (Repeated Measures ANOVA, P<0.05). This was

Jan 6, 2006

By John A. Davis, David W. Brunton

During the past few years great progress has been made in the United States toward safer, more efficient, and more economical tunneling methods. This advance is partly due, no doubt, to the recent increase in the number of tunnels and adits driven for devel- oping and draining mines and transporting ore. The Bureau of Mines during 1911 and 1912 made a special examination of this phase of mining operations, in connection with an investigation of mining methods and means for preventing accidents. The details especially studied were the provisions for the safety of employees, the kinds of equipment, the methods of driving, and the costs of con- struction. The results and conclusions obtained from that investi- gation are discussed and summarized in this bulletin. Up-to-date information concerning tunneling methods is difficult to obtain. There are few books on the subject; and much of the material they contain, although interesting and of value historically, is now obsolete. The engineering periodicals, it is true, endeavor to keep abreast of the times, and several in nearly every issue present some article bearing upon tunnel work. But the very multiplicity of these articles prevents one from reading them all, and the foreman or superintendent in charge of a tunnel, or the mining engineer designing one, and especially the business man financing the project, has no time for a lengthy search after scattered articles in order to determine the present status of tunnel work. Then, too, knowledge of new methods travels slowly. Valuable inventions and improve- ments in tunneling as well as in all the other industries frequently remain in the notebook of the investigator, or as theses are buried in university libraries, or are published only in journals of small scien- tific societies. New tunneling methods and equipment that are prov- ing safe, efficient, and economical may be totally unknown outside the district in which they originate. This paper, based on a special examination both in the field and in engineering literature, is in- tended to supply data concerning modern and recent tunneling practice in the United States, and to make suggestions that, it is hoped, will result in a saving to the mining industry of energy, capital, and life.

Jan 1, 1916

By S. J. Schatzel, W. P. Diamond, F. Garcia

Methane explosions have historically been one of the major causes of fatalities and injuries in underground coal mining operations. Advanced numerical models and predictive modeling approaches have the potential to offer optimized methane control solutions for general mine planning purposes and to address specific methane-related operational problems. This paper describes the development of reservoir models for the longwall mining environment and their application for investigating the influence of various completion design parameters on the methane drainage effectiveness of gob gas ventholes. The influence of increasing longwall panel width on the effectiveness of current gob gas venthole completion and placement strategies in the Pittsburgh Coalbed were evaluated and optimized designs developed to capture the expected increase in methane emissions on the larger panel.

By R. J. Fantel

The Bureau of Mines investigated the resource availability of titanium minerals from 63 mines and deposits in 12 market economy countries. These mines and deposits contain, at the demonstrated resource level, an estimated 438 million metric tons (mt) of titanium dioxide (TiO2) in the minerals rutile, ilmenite, leucoxene, and anatase. An additional 314 million mt of TiOz is available from inferred resources. If all titanium minerals and other recovered heavy minerals are sold at total costs at least equal to the January 1984 market prices, approximately 200 million mt of contained TiO2 could be recovered in total. In terms of mineral concentrates, this equals approximately 11 million mt of rutile concentrate, 187 million mt of ilmenite concentrate, 3 million mt of leucoxene concentrate, 13 million mt of synthetic rutile concentrate (in addition to the ilmenite), and 89 million mt of titanium slag. The study indicates that world resources of low-cost rutile are declining. In order to maintain future supply for high-grade titanium resources, alternate sources will need to be developed, which may include higher cost rutile mines, Brazilian anatase deposits, increased production from slag operations, or more synthetic rutile capacity from ilmenite resources, which are abundant.

Jan 1, 1986

By Chas. F. Jackson

During the past 5 years the Bureau of Mines has published information circulars dealing with mining methods and costs at 78 ore mines; 7 circulars, each of which is devoted to a discussion of one of the principal mining, methods; and 23 circulars dealing with special phases of mining, such as ventilation, shaft sinking, tunnel driving, the cost of equipping and developing prospects and small mines, underground transportation, diamond drilling, and ground support. These circulars were written by many different authors, and in order that the method of presentation and the basis for compilation of data might be the same in all the papers the Bureau drafted an outline to be followed in their preparation. To clarify the data in these circulars, which are in the libraries of many engineers and mining companies, and the summarized data presented in this paper, that portion of the outline dealing with cost and labor-performance data is reproduced below.

Jan 1, 1934

By Gerald T. Homce, James C. Cawley

This paper updates an earlier report by the authors that studied electrical injuries from 1992 to 1998. The previous information is expanded and supplemented with fatal and nonfatal injury rates and trends through 2002. Injury numbers and rates were used to compare and trend electrical injury experience for various groups and categories. This information allowed identification of at-risk groups that could most benefit from effective electrical safety interventions. The data presented in this paper are derived from the U.S. Labor Department’s Bureau of Labor Statistics’ Census of Fatal Occupational Injuries (CFOI), Survey of Occupational Illnesses and Injuries (SOII) and Current Population Survey (CPS). Between 1992 and 2002, 3,378 workers died from on-the-job electrical injuries. Electricity remained the sixth leading cause of injury-related occupational death. From 1999 through 2002, 4.7% of all occupational deaths were caused by electricity, down from 5.2% in the 1992 to 1998 time period. The cause of death was listed as electrocution in 99.1% of fatal cases. Contact with overhead power lines was involved in 42% of all on-the-job electrical deaths. The construction industry accounted for 47% of all electrical deaths between 1992 and 2002, but showed overall improvement from 1995 through 2002 by reducing its electrical fatality rate from 2.2 to 1.5 per 100,000 workers. An additional 46,598 workers were nonfatally injured by electricity. Contact with electric current of machine, tool, appliance, or light fixture and contact with wiring, transformers, or other electrical components accounted for 36% and 34% of nonfatal electrical injuries, respectively. Contact with underground, buried power lines was involved with 1% of fatal injuries and 2% of nonfatal injuries. NIOSH research aimed at evaluating commercially available overhead power line proximity warning alarms is described. This research is expected to be the initial step for eventual development of a performance standard for such systems.

A new mine has begun production of antimony ore and concentrates in Serbia, Yugoslavia. The mine is operated by the mining and metallurgical enterprise "Aajaca." Initial production is running at approximately 45 thousand tons of ore per year, yielding about 1,500 tons of concentrate. The mine is located on the mountain Kopaonik-Raiceyoj Gori. It is planned to expand production eventually to approach the level of 300,000 tons of ore per year. This level will be a significant addition to the world supply of antimony and will place Yugoslavia among the world&apos;s major producers. Currently the United States produces only about 6 percent of its primary requirement for antimony. COBALT -Anglo American Corporation, Ltd. reportedly is considering restarting the Tenke-Fungurume copper-cobalt project in Zaire. Construction on the project was suspended in January because of inadequate financing and political uncertainties. Technical feasibility and financing on a smaller scale than previously envisioned are now being considered. However, an increased copper price may be necessary before any decision to proceed is made.

Jan 1, 1976

By Dennis R. Dolinar, Jeff Dubbert, Hamid Maleki

The advance-and-relieve method benefits from lateral destressing associated with mining in laminated rocks and a high horizontal stress regime. This stress control method is based on measurements showing that occurrence of rock failure in the roof and floor of an entry (or caving of roof strata in a panel gob) results in redistribution of stresses in adjacent entries. By locating other entries within the shadow zone of the first entry (or gob), improvements in stability can be achieved. Numerical modeling proved useful in studying the basic mechanics of lateral relief while investigating the sensitivity of results to different geologic and mining parameters using controlled experiments. It was shown that failure of rocks near an entry results in redistribution of horizontal stress and shifting of the stress to higher horizons. Measurements from two mines are consistent in showing significant horizontal stress reductions in comparison with the far-field stress regime within the destressed zone. Although the far-field stress regime is very anisotropic, these measurements show near-equal secondary principal horizontal stresses, or perhaps a switch in orientation, as a result of destressing. Stress relief is achieved through lateral movement and relaxation of rocks along weak bedding planes toward adjacent caved zones (or softened zone). Because of cave geometry in the advancing panel, horizontal stress concentrations occur near the cave line both in front of the face and to the sides. The horizontal stress concentration reaches 1.7 times the far-field stress ahead of the face. This stress increase is significant and may cause structural damage in this zone benefiting from additional support. In the next advancing panel located within the shadow zone of the gob, horizontal stresses are significantly reduced in the roof (by 50%). Thus, the stability of future advancing panel can be improved through prudent layout designs and sequencing. The width of the relief zone is significantly influenced by the height of the softened (or cave zone) and rock mass properties.

By Charles M. McCulloch

This Bureau of Mines report discusses the principles of using computers to draw maps and plot geologic data of mining areas. The types of maps that can be drawn by a computer are reviewed, using as examples two separate areas where poor roof and gas emissions caused mining problems. Such maps can be used not only to help identify problem areas, but also to predict areas where problems could occur, thus giving mine operators time to work out solutions prior to mining. The average cost of a computer-drawn map for a mine property is less than $100, including computer time and man-hours for data preparation.

Jan 1, 1976

By John P. Gooch

The solubility of 1,1,2,2-tetrabromoethane (TBE) in water was determined from 1.0° to 97.0° C. The solubility (S) of TBE in grams of solute per 100 grams water was correlated with [S = 1,920.55 [exp (40292L7 11, T2 10 T 737.577 + 9.923962 ] where T is in degrees Kelvin. A thermodynamic analysis conducted on a system consisting of a TBE phase and a water phase in equilibrium with a vapor phase led to the calculation of the activity coefficient, vapor-liquid equilibrium distribution coefficient, relative volatility, and heat of mixing for saturated solutions of TBE in water. Data required for these calculations were the solubility of TBE in water and the vapor pressures of TBE and water as a function of temperature.

Jan 1, 1972

By John E. Urosek, Dennis A. Beiter, William J. Francart

In This Chapter [Designing bleeder systems Examining and maintaining bleeder systems Evaluating bleeder system effectiveness] INTRODUCTION Bleeder systems are that part of the mine ventilation network used to ventilate pillared areas in underground coal mines. Pillared areas are those in which pillars have been wholly or partially removed, including the areas where coal has been extracted by longwall mining. Bleeder systems protect miners from the hazards associated with methane and other gases, dusts and fumes, and oxygen deficiency that may occur in these mined-out areas. Effective bleeder systems control the air passing through the area and continuously dilute and move any methane-air mixtures and other gases, dusts, and fumes from the worked-out area away from active workings and into a return air course or to the surface of the mine. A bleeder system includes the pillared area (including the internal airflow paths), bleeder entries, bleeder connections, and all associated ventilation control devices that control the air passing through the pillared area. Bleeder entries are special air courses designed and maintained as part of the mine ventilation system. [This chapter focuses on the design, examination, maintenance, and evaluation of bleeder systems in underground coal mines.] The history of coal mine explosions in the United States is a reminder of the importance of adequate ventilation. Some of those disasters were the result of inadequately ventilated pillared areas. The importance of developing bleeder systems to ventilate these pillared areas and evaluating the bleeder system’s effectiveness is reflected in present-day federal regulations. For more information on bleeder systems, see Tisdale [1996] and Urosek and Francart [2002].

Jan 6, 2006

By Frank B. Fulkerson

Mining began in Pend Oreille and Stevens Counties about 1885, Lead and zinc have been the principal products, and the area has supplied nearly all the output of these metals in the State. Fend Oreille County&apos;s output of lead and zinc from 1902 to 1956 was 110,700 and 229,600 tons, respectively. The Stevens County total was 54,100 tons of lead and 87,600 tons of zinc. Copper ore was produced mainly from the United Copper mine, Chewelah district, from 1912 to 1920; the principal gold mine was the First Thought, Orient district, which was active from 1904 to 1942. Approximately 225 mines and prospects produced; most of the ventures were on a small scale. The total value of gold, silver, copper, lead, and zinc produced from 1902 to 1956 was $75.2 million in Pend Oreille County and $39.4 million in Stevens County. INTRODUCTION In compiling the figures for this report, use was made of Bureau of Mines permanent records of nine production, the annual tabulations of producing mines, and the Minerals Yearbook. Requests to publish individual data, obtained from the annual production canvass, were made to the latest recorded operators of all mines in the area. Response to this request was good; therefore, it was possible to make the tables nearly complete. In a few instances the producer requested that the production data remain confidential, and in others it was not possible to reach the mine operator at his last known address. The district and county tables combine statistics for all mines, including those mines whose output could not be published separately.

Jan 1, 1958

By Shiro Watanabe

To determine the potentialities of nickel as a substitute for cobalt in catalysts for the synthesis of hydrocarbons from carbon monoxide and hydrogen, RESULTS The maximum oil yields obtained in bench-scale equipment were as follows: Using 100N1:20Mn:100 kaolin:200 diatomaceous earth catalyst, a maximum yield of 133.8 cm.3/m.3 of pure CO+2H2 was obtained from one pass of the feed gas, With a nickel:cobalt mixed catalyst (Ni:Co - 3:7) having the composition 100(Ni+Co):8MgO: 5Th02:200 diatomaceous earth, a maximum of 172.2 cm.3/m.3 of pure C0+2H2 was obtained.

Jan 1, 1951

The accompanying supply/demand flow diagrams and 10-year tables for mineral and fuel commodities present essential data required by government, industry, and others to formulate policies and programs that can help assure an adequate and continuing supply of mineral raw materials. The 10-year data base terminates with 1974 figures because adequate world information was not available beyond that date. The selected mineral supply/demand tables and flow diagrams comprise but one "output" from the massive body of information and data collected and com-piled by the Bureau of Mines on a continuing basis covering mineral production, consumption, prices, shipments, imports, exports, and stocks, as well as industry activities in all States and abroad.

Jan 1, 2012

By D. E. Van Dillen

Seven configurations for panel entries of a longwall coal mine are compared and ranked according to structural stability. These entry configurations are analyzed using three-dimensional finite element modeling The models include large dimensions to minimize boundary effects, elastoplastic constitutive relations, and simulated excavation and construction of support systems. The stability criteria are formulated in a quantitative manner to facilitate the ranking of the entry configurations. These criteria are based on the expected volume of caved rock in the entry openings. The stability ranking is applied to the entry excavation phase, the headgate phase, and the tailate phase of the entry life cycle. Parametric variations are applied using two-dimensional finite element models to determine the sensitivity to changes in mining and design parameters.

Jan 1, 1981

By Nabil A. Bibawy

The U.S. Bureau of Mines has established a method for the calibration of class 2 and class 4 standards of mass using a procedure from designs developed by the National Institute of Standards and Technology (NIST). This method produces a weight calibration that is within 1.0 pct of the balance sensitivity. A set of four 1-kg weights yielded a standard deviation of 3.25 mg compared to ±2.91 mg balance sensitivity. The method employs the use of a high-accuracy balance to measure the difference between a set of weights calibrated by NIST and the set to be calibrated. The error of the balance is included in the error for each weight calibrated.

Jan 1, 1989

By M. J. Ferrante

A process was investigated for preparing Specification-grade nickel (containing less than 1 percent cobalt) by stripping it electrolytically from a nickel sulfate-boric acid solution and using the stripped electrolyte for the preferential dissolution of nickel from basic carbonates of nickel and cobalt. The basic carbonates were produced at the plant at Nicaro, Cuba, owned by the U.S. Government. Determination of the optimum conditions for deposition of Specification-grade nickel indicated that the upper limit of cobalt concentration was 0.1 gram per liter. The pH, temperature, and concentrations of nickel and boric acid in the electrolyte were not critical. An aluminum cathode and two lead anodes were used at a cathode current density of 1.2 amperes per square decimeter.

Jan 1, 1959

By Sidney Katell

This report, covering the period January 1969 through December 1969, is a continuation of a series that began with the publication of Information Circular 7516 in October 1949. It is the 11th in a series of reports prepared in cooperation with the American Association of Cost Engineers. The abstracted articles are concerned with all phases of cost engineering in the field of chemical and petroleum plants and related subjects. They are from the following sources: 1. American Association of Cost. Engineers Bulletin. 2. Bureau of Mines Information Circulars. 3. Bureau of Mines Reports of Investigations. 4. Chemical Engineering. 5. Chemical Engineering Progress. 6. Chemical Week. 7. Coal Age. 8. Coal Mining and Processing.

Jan 1, 1970

In 2005, a total of 7,111 sand and gravel mining operations reported employment to the Mine Safety and Health Administration (MSHA). ? Sand and gravel mines were the largest mining sector, comprising 48.5% of all mining operations. ? Sand and gravel mines were found throughout all 50 states and Puerto Rico.

Sep 1, 2008