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By D. S. DeLong, A. Giza, D. G. Fraser, V. A. Robinson, T. B. Whitmoyer, J. E. Sneckenberger

"A cotton dust animal exposure system has been modified to incorporate a microcomputer feedback loop to monitor particle concentrations. The loop's major components are a minature real-time aerosol monitor (miniram) to estimate concentrations and a microcomputer to read the miniram's data and to control a stepper motor that adjusts the amount of dilutant air mixing with respirable cotton dust. Ninety minute trials of this system indicate that the standard deviation of particle concentrations is within 0.68 Mg/m3 of the average concentration, insuring a near constant concentration of respirable dust throughout the exposure.INTRODUCTION Previous workWeyel et al. (1984) have determined that respirable cotton dust can be shaken from bulk cotton samples using acoustical energy. The particle generator designed to utilize this fact operates like a commercially available sonic sifter, but on a much larger scale.While this generator successfully resuspended trapped respirable cotton dust, the generator output concentration decreased exponentially with time. This disadvantage was solved by Frazer et al. (1986) by operating the generator with a sinusoidal voltage near the minimum resonance frequency of the generator. This adjustment enabled the generator to produce respirable cotton dust for six hours or longer.Frazer et al. (1987) utilized the modified acoustical generator to produce a cotton dust animal exposure system. The cotton dust concentrations were estimated by a miniram, a light scattering aerosol Monitor. The system operator used the miniram values to adjust the system's parameters to maintain the desired concentration level.PurposeThe objective of this study was to introduce a computerized feedback loop to the operator controlled cotton dust animal exposure system. The miniram's estimates were analyzed by a microcomputer to determine what adjustments in the flow of dilutant air were necessary to maintain the desired cotton dust concentration. These modifications were intended to improve system performance and ease the system operator's work burden."

Jan 1, 1988

The Bureau of Mines Minerals Information organization collects worldwide data on virtually every commercially important nonfuel mineral commodity. These data form the base for tracking and assessing the health of the minerals sector of the U.S. economy. This data collection activity was instituted by the 47th Congress in an appropriations act of August 7. 1882 (22 Stat. 829) to place the collection of mineral statistics on an annual basis. The most recent authority for the Bureau of Mines Minerals Information activity is the National Materials and Minerals Policy, Research and Development Act of 1980 (Public Law 96-479, 96th Congress), which strengthens protection for proprietary data provided to the U.S. Department of the Interior by persons or firms engaged in any phase of mineral or mineral-material production or consumption.

Jan 1, 1987

By Gerrit V. R. Goodman, Fred N. Kissell, Charles D. Taylor

In This Chapter [Methane emission peaks Exhaust line curtain or duct The spray fan system Dust scrubbers with blowing ventilation Dust scrubbers with exhaust ventilation The ventilation of abnormally gassy faces Methane detection at continuous miner faces Ventilation and methane detection at bolter faces and Reducing frictional ignitions] This chapter gives guidelines for preventing methane gas explosions at continuous miner sections in coal mines, both at continuous miners and at roof bolters. The need to control peak methane emissions is particularly stressed. Emphasis is also placed on ventilation principles, monitoring for gas, and reducing frictional ignitions. METHANE EMISSION PEAKS Methane emission from the coal at continuous miner faces varies considerably. Plotted on a chart, methane emissions consist of a series of peaks and valleys corresponding to the cutting cycle of the mining machine, with the methane concentration spiking as the machine cuts into the coal (Figure 3–1) [Kissell et al. 1974]. These methane peaks can be substantial. For this reason, efforts to safely dilute the methane must focus on the level of the [ ]

Jan 6, 2006

By Harold W. Lipper

HELIUM shipments in 1963 exceeded the volume shipped during the previous year for the 14th successive time. Shipments from Bureau of Mines plants were 627.3 million cubic feet, an increase of 5 percent over the volume shipped in 1962. Production from Bureau of Mines plants totaled 774.2 million cubic feet. The Bureau purchased 1,420 million cubic feet of helium in the helium conservation program and stored it underground for future use. Each of the five plants, financed and built by private industry for helium conservation, made deliveries during the year. Helium continued to playa key role in space, atomic energy, defense, and other research programs. Additional capacity for liquefying helium became available, and the first civilian helium-cooled nuclear-powered reactor in the United States began pre-operation testing.

Jan 1, 1964

By P. Yant, A. C. Fieldner

"IntroductionIn its investigations relative to reducing the hazards of carbon monoxide poisoning, the Bureau of Mines recently had its attention drawn to a compound2a sold under a trade name for which claims are reported to have been made regarding its efficacy in reducing that type of poisoning in automobile garages. Accordingly, some of the product was obtained and analyzed for its power to absorb, oxidize, or destroy carbon monoxide; and the results are herein reported.Description of ""Compound"" (quoted from manufacturer's circular)While the circular does not actually state that the ""compound"" protects against carbon monoxide, the inference is therein, because each of the two following quotations is below these respective headings; ""Carbon-Monoxide Poisoning,"" and ""Chronic Gassing Among Garage Workers.""The ""compound"" holds chlorine and oxygen gases in solution with formaldehyde, which unites with the hydrogen to form hydrochloric acid., giving an over-supply of oxygen which burns up carbon just as a piece of wood is burned in the fire. The formaldehyde in the composition of the ""compound"" is a great affinity for ammonia and hydrogen sulphide."

Apr 1, 1924

By K. O. Bennington

Enthalpies of formation of three sodium titanates were determined by hydrofluoric acid solution calorimetry, The values obtained for formation from the elements at 298.15° K are -370.9±0.5 kcal/mole for Na2TiO3, -832.1±0.9 kcal/mole for Na2Ti307, and -1,510.9±1.7 kcal/mole for Na2Ti6013. Tables of enthalpies of formation and Gibbs energies of formation are given as a function of temperature both from the elements and from the component oxides for Na2Ti03 and Na2Ti307.

Jan 1, 1973

By David C. Oyler, Gregory Hasenfus, Gregory M. Molinda

Few studies have specifically measured and documented the large-scale loading behavior and durability of ventilation stoppings to mining induced movements, particularly from longwalls. Ventilation stoppings are more commonly the concern of ventilation engineers, and ventilation stopping response to ground movement has only been documented in an incidental manner. This paper presents the investigations of underground measurements that have been conducted to determine the loading response of stoppings constructed from lightweight aggregate concrete masonry units (CMU). These investigations have produced some interesting results that may prove beneficial, not only for developing and assessing alternative stopping construction techniques, but also for designing and selecting standard construction methods for use in varying mining conditions. For instance, the interface friction that results from wedging a CMU stopping during construction plays a substantial role in its ability to resist both lateral and vertical loads. Although they are not intended for ground support, the study showed that block stoppings can resist vertical loads of at least 2,700 to 3,000 kN. Asymmetric loading of a stopping may result in localized failure of blocks within a stopping, which, depending on the severity, can be a precursor of impending stopping failure. In addition to measurement results and implications, the paper will also present details of field measurement methods used to assess stopping response. Stopping stiffness and material strength characteristics will also be presented.

By James S. Browning

The Bureau of Mines conducted laboratory and small-scale continuous tests of kyanite ore from Georgia to determine the technical feasibility of recovering commercial-grade kyanite concentrates by flotation. The research indicated that combinations of sulfuric acid and petroleum sulfonate may be used effectively for flotation of kyanite from quartzite-kyanite ore. Over 87 percent of the kyanite was recovered in a concentrate analyzing 55.8 percent A1203 and 5.3 percent acid-soluble Fe203. Subsequent treatment of the flotation concentrate by high-intensity wet magnetic separation reduced the acid-soluble Fe203 to 0.8 percent and increased the alumina content to 57.6 percent, with a recovery of 82.7 percent of the total alumina in the ore.

Jan 1, 1970

By R. W. Dalzell, Fred N. Kissell, J. L. Banfield, M. G. Zabetakis

Methane concentration peaks were measured by the Bureau of Mines at coal mine working faces during entry development. The statistical distribution of peaks was found to be normal or log normal depending on how well the methane was being mixed into the ventilation airstream. A normal distribution indicated good mixing, whereas a log-normal distribution indicated that mixing was poor. In addition, the "highest" peaks over selected intervals were found to fit a type I extreme-value distribution, a result similar to that obtained while mining longwall faces.

Jan 1, 1974

By M. G. Zabetakis

The method of moving averages was found useful in assessing the nature of methane emission in coal mines. Emission rates were influenced markedly by the presence of abandoned oil and gas wells in the vicinity of the mine. Such wells appeared to increase the flow rate of methane into the mine by a factor of 2 to 30 in an active mine in the Pittsburgh coal seam.

Jan 1, 1972

By W. F. Marshall

The Bureau of Mines conducted a series of experiments to determine the influence of exhaust rebreathing on emissions from various gasoline and diesel engines. Tests were conducted that simulated operation of engines in nonventilated spaces as well as in spaces with partially restricted ventilation. Results of these tests showed that exhaust rebreathing can have a marked effect on exhaust emissions and thus on the composition of the air in the working space. For the case of restricted ventilation, unacceptably high (greater than 50 ppm) levels of CO in the air of the working space resulted from exhaust rebreathing rates as low as 8 pct exhaust in the engine's intake. Operation in a nonventilated space resulted in highly critical CO levels (fatal in a few minutes) at times corresponding to 1 to 3 pounds of fuel consumed per 1,000 cu ft of space. Tests involving spaces of various sizes showed that volume of the air space [per se] is not important--the primary variable is fuel consumed per unit volume of air space.

Jan 1, 1973

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

MINE VENTLATION NETWORK ANALYSIS

Jan 1, 1977

By Robert W. Freedman

This report describes sampling and analytical procedures used for measurement of sulfates in diesel tailpipes and in the diluted exhaust within dilution tunnels. A variety of methods exist for sulfate analysis for such systems, including ion exchange. Two chemical methods used by the Bureau of Mines are described in detail. These are based upon spectrophotometric measurement of chloranilic acid using barium chloranilate. The procedures are rapid and relatively inexpensive. In general, ion exchange is preferred by many analysts for sulfate analysis. However, it is more complex and expensive than chloranilic acid procedures, which are adequate for exhaust analysis.

Jan 1, 1982

By Ben A. Kornhauser

Benin's industrial sector experienced severe economic and financial problems in 1986, including disappointing performances of the Onigbolo cement plant and the Semé Oilfield, plus a shortage of technically trained personnel and experienced management. Oil production remained about 1,000 barrels per day. Import and export trade between Benin and the United States remained minimal. Because much of Benin's outstanding external debt was in U.S. dollars, the stronger dollar greatly increased the debt burden. The 1985 budget of $304 million' was composed of an investment budget of $194 million and a current budget of $110 million. Of the investment budget, 84% was expected to be externally financed. About $45 million was given to three priority projects: the joint Benin-Togo Nangbeto hydroelectric project scheduled for completion in 1986; drilling of new exploratory wells of the Semé petroleum project, and the Dassa-Parakou highway. The budget deficit was projected to exceed $43 million despite a decrease in projected revenue owing to an anticipated decline of 25% in import tax revenue, normally the largest source of Government revenue.

Jan 1, 1987

By R. V. Ramani, V. T. Burgos, J. A. McClay

Cost Systems Cost systems are organized methods of collecting, allocating, and accumulating resource utility expressed in terms of money. There are two major spheres of cost accumulation: financial accounting and cost accounting. Financial accounting deals primarily with historical costs and provides a means of measuring and recording cost events which have al¬ready taken place. While there are no legal requirements to control the methods of recording and reporting cost data in the United States, the procedures in use are guided by professional organizations such as the American Institute of Certified Public Accountants. The final pro¬ducts of financial accounting practices are the income statement and balance sheet which describe the financial status of the organization under study. Cost or managerial accounting is an expansion of financial ac¬counting procedures, providing more detailed cost breakdowns on present operations with one objective being the projection of present costs into the future. The projection process tends to limit the accuracy of the information; however, to management and project justification per¬sonnel, data on future operations tends to be of greater value. The basic principle behind cost accounting is the cost cycle. As products are developed from raw materials, the value of the work-in¬process increases due to the cost input of the various fabricating ele¬ments. Thus, from the basic input elements of facilities, labor, and raw materials, costs are added to each unit of production as a function of the work performed on that unit.

Jan 1, 1975

By Daniel N. Tallman

To provide technology for achieving more efficient water filtration systems for the mineral industry, the Bureau of Mines performed demon-stration filtration tests at three iron ore mines and one steel mill. A comparison of equivalently sized magnesium oxide (MgO) and sand filters showed that MgO had a higher capacity and could operate at higher fil-tration rates than sand. In demonstration tests when alum (AlK(S04)2) was the coagulant, suspended solids breakthrough occurred even though the pressure across the filter (head loss) was 7 psig or less. Under these circumstances, the MgO demonstrated 20 to 100 pct greater filtra-tion capacity, defined in terms of the volume of water filtered before breakthrough. When an organic floccu1ant was used at one location, head loss was the run-limiting factor; the filters essentially plugged with-out any solids breakthrough.

Jan 1, 1985

By Gordon H. Dechman

This Bureau of Mines report presents an iterative approximation method for microseismic source location that was developed to adapt microseismic techniques for rock structure analysis to investigations of surface problems, such as slope failure in an open pit mine. The source location method and two derivative location algorithms are described in detail, and the speed and accuracy of the two algorithms are compared.

Jan 1, 1977

By W. H. Eddy

The Bureau of Mines conducted laboratory batch and continuous flotation processing tests on waste granite fines from South Carolina to determine the possibility of recovering high-quality feldspar and glass sand. Three flotation systems were used for removal of the iron-bearing biotite: Two employed an alkaline anionic-cationic circuit and the third employed an acid cationic circuit. Commercial-grade products were obtained when the remaining biotite was magnetically removed from the feldspar and quartz concentrates. Continuous flotation processing yielded a feldspar concentrate containing, in percent, 3.60 Na20, 5.60 K20, and 2.25 Ca0, with recoveries of 75.3, 66.6, and 72.6 percent, respectively. The feldspar tailing was high quality glass sand containing 98.0 percent Si02 and 0.025 percent Fe203; about 60 percent of the quartz was recovered.

Jan 1, 1972

By Charles C. Hwang

In this Bureau of Mines report, a previously developed theory of reverse stratified flow in ventilated duct fires is applied to mine-related ventilation systems that utilize an exhaust fan to supply the forced airflows. The coupling between a fire and the ventilation airflow in a single-entry duct is analyzed to relate the air velocity in the absence of a fire to air velocity during a fire. By combining the derived coupling equations with the results of the previously developed theory of reverse stratified flow, it is possible to calculate critical flow velocities required to prevent reverse stratified flow in the event of a duct fire. The sample calculations shown agree with the few experimental results available from small-scale tunnel fires.

Jan 1, 1978

By J. Brad Seymour, Mark K. Larson, Richard L. Rains, Douglas R. Tesarik

For several years, researchers from the Spokane Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) have been using geotechnical instruments in underground mines to study ground control problems and develop means of reducing accidents and fatalities caused by ground falls. This paper describes many of the different types of instruments, sensors, and data acquisition equipment that have been used for these studies; briefly explains the advantages and disadvantages of various sensor technologies; provides practical recommendations regarding the use of specific instruments and data acquisition systems; and outlines a general approach to the design and implementation of a successful instrumentation plan. A wide variety of instruments are commercially available for measuring deformation, strain, stress, and/or load. If used correctly, these instruments can provide important quantitative information regarding the mining-induced behavior of the host rock, the performance of ground support systems, and the safety and stability of underground workings. Data collected from these instruments can warn mine staff of impending ground control failures or hazardous working conditions, as well as provide valuable information for the design of ground support systems and the configuration and sequencing of mining excavations. We hope that the practical information presented in this paper will encourage a more widespread use of geotechnical instruments in underground mines and lead to reliable measurements that aid the engineering decisions affecting the safety of miners.

Jan 10, 2000