Search Documents

By S. J. Anderson

The Bureau of Mines compared three methods of rock cutting using drag cutters under controlled laboratory conditions. The methods tested were the conventional drag cutting method used on continuous miners, the kerf-core method used on some boring machines, and an experimental method called ripper cutting. All three methods were tested in blocks of Indiana and Kasota limestone. The results of this testing showed ripper cutting to be 30 to 40 pct more energy efficient than both the conventional and the kerf-core methods in Kasota limestone and 35 pct more efficient than the kerf-core method in Indiana limestone. The conventional method was, however, 9 pct more energy efficient than the ripper method in Indiana limestone. These results are considered promising, and more tests are planned with the ripper cutting system.

Jan 1, 1987

By D. G. Kesterke

Research was conducted to determine the feasibility of extracting elemental oxygen from silicate-bearing melts by high-temperature electrolysis. The method was based on a modification of existing processes for electrowinning metals from their oxides dissolved in molten halide systems. Electrolyses were performed at temperatures ranging from 1,050° to 1,250° C in boron nitride cells that incorporated a silicon carbide cathode and an iridium anode. The electrolytes contained volcanic scoria as the oxygen source, plus mixtures of BaF2 and LiF as fluxing agents. Cell gases containing almost 14 volume-percent oxygen were obtained. The average anode current efficiency for several experiments of extended duration was calculated to be 55 percent. Cell design and operating conditions are described, and some of the problems associated with the process are discussed.

Jan 1, 1971

To develop and design a bit that will rapidly drill smooth and precise instrumentation holes in soft rock. Approach Use a one-piece bit made by combining a drag bit and a diamond bit. Because a smooth-walled borehole with a precise diameter is needed for borehole pressure cells (BPC) and other borehole instruments, a diamond bit is usually used. However, diamond bit drilling is slow, and the bit will tend to bind when squeezing ground is encountered. On the other hand, the drag bit will cut faster, but the walls of the drill hole will be rough and the diameter will not be as precise. The combination will provide a bit which penetrates as rapidly as a drag bit, but retains the smooth-wall and precise borehole diameter of a diamond bit. How It Works A three-foot-length of EW-size drill rod is centered in a diamond bit by welding it to three equally-positioned spacers at each end of the bit. A drag bit is attached to the EW rod with a standard EW-to-drag bit adapter as shown in the diagram. Three equally-spaced diamond inserts are set to the desired hole size and welded to the diamond bit barrel behind the crown. These inserts increase the smoothness and precision of the hole by cut-ting away any hole closure. Three equally-spaced shims are set approximately 0.020-inch under the overall insert diameter size and welded to the rear of the diamond bit barrel. The combination bit should be used on a diamond drill with either water, mist or air as the coolant.

Jan 1, 1982

By Isaac A. Zlochower, Kenneth L. Cashdollar

The Pittsburgh Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) conducted a study of the explosibility of various metals and other elemental dusts, with a focus on the experimental explosion temperatures. The data are useful for understanding the basics of dust cloud combustion, as well as for evaluating explosion hazards in the minerals and metals processing industries. The dusts studied included boron, carbon, magnesium, aluminum, silicon, sulfur, titanium, chromium, iron, nickel, copper, zinc, niobium, molybdenum, tin, hafnium, tantalum, tungsten, and lead. The dusts were chosen to cover a wide range of physical properties-from the more volatile materials such as magnesium, aluminum, sulfur, and zinc to the highly "refractory" elements such as carbon, niobium, molybdenum, tantalum, and tungsten. These flammability studies were conducted in a 20-L chamber, using strong pyrotechnic ignitors. A unique multiwavelength infrared pyrometer was used to measure the temperatures. For the elemental dusts studied, all ignited and burned as air-dispersed dust clouds except for nickel, copper, molybdenum, and lead. The measured maximum explosion temperatures ranged from "-1550K for tin and tungsten powders to "-2800K for aluminum, magnesium, and titanium powders. The measured temperatures are compared to the calculated, adiabatic flame temperatures.

By R. Barany

The heat of formation at 298.15 ° K of muscovite was determined by solution calorimetry . The value obtained for the heat of formation from the elements was -1,421.2 ± 1.3 kcal / mole , and the value for the heat of formation from the oxides was -55.9 ± 1.3 kcal /mole .

Jan 1, 1964

By Thomas C. Miller, Rudolph Sporcic

A relatively simple and inexpensive encapsulated hydraulic device has been developed by the Bureau of Mines to facilitate study of coal bumps , and to measure pressure changes in a coalbed as it is subjected to roof loading during mining . Construction of the device and application techniques are described . Preliminary feasibility tests in the laboratory and field indicate that the device responds satisfactorily to pressure changes in coal created by roof loading .

Jan 1, 1964

[ ]

Jan 1, 2012

By F. D. Osgood, A. C. Fieldner, W. A. Selvig

In connection with investigations being conducted by the Bureau of Mines regarding pulmonary disease which is prevalent among metal miners in certain districts , a large number of rock- dust samples have been collected , and have been examined in the Bureau's laboratories . The earlier work has been described in Bureau of Mines Technical Paper 105 , " Pulmonary disease among miners in the Joplin district , Missouri , and its relation to rock dust in mines " by A. J. Lanza and Edwin Higgins , 1915 , and in Bureau of Mines Bulletin 132 , " Siliceous dust in relation to pulmonary disease among miners in the Joplin district , Missouri , " by Edwin Higgins , A.J. Lanza , F.B.Laney , and Geo . S. Rice , 1919. The methods of collecting and examining dust samples have been greatly improved during the investigation , much valuable information having been made available by similar investigations conducted by the Miners ! Phthisis Prevention Committee , Union of South Africa . The latter are described in the " General report of the Miners ' Phthisis Prevention Committee , Johannesburg, Union of South Africa , 1916 " , and " Final report of the Miners ' Phthisis Prevention Committee , Johannesburg, Union of South Africa , 1919. " The investigations by the Bureau of Mines and the South African committee show that by prolonged inhalation of air containing minute particles of sharp and insoluble rock dust , the lungs retain sufficient dust particles to cause decided injury to the lung tissue , the injured lung becoming very susceptible to the development of tuberculosis .

May 1, 1920

By H. C. Ko

As part of the Federal Bureau of Mines effort to provide thermodynamic data for the advancement of minerals technology, energy conservation, and environmental preservation, the standard enthalpies of formation of a-magnesium sulfate, a-magnesium sulfate, and magnesium sulfate monohydrate were determined by hydrochloric acid solution calorimetry. The values of the standard enthalpies of formation in kcal per mole at 298.15 K are -307.95 ± 0.13 for a-MgS04, -307.03 ± 0.13 for ß-MgS04, and -384.72 ± 0.13 for MgS04 .H2O.

Jan 1, 1979

By J. A. Organiscak

Enclosed cabs are a primary means of reducing the silica dust exposure of equipment operators at surface mines. The National Institute for Occupational Safety and Health (NIOSH) has investigated various factor effects on enclosed cab air filtration system performance. Factors experimen­tally investigated were intake filter efficiency, intake air leakage, intake filter loading (filter flow resistance), recirculation filter use and wind velocity effects on cab penetra­tion (inside to outside cab concentration ratio). Adding an intake pressurizer fan to the filtration system was also investigated. Results indicate that the intake filter efficiency and recirculation filter were the two most influential factors on cab penetration. Use of a recirculation filter significantly reduced cab penetration over the intake air filter by itself due to the multiplicable filtration of the cab interior air. Cab penetration was also affected to a lesser extent by intake filter loading and air leakage. Adding an intake pressurizer fan notably increased intake airflow and cab pressure while providing only minor changes to cab penetration.

Jan 1, 2008

By William A. Hoffman

In This Chapter [MSHA regulations for coal mines MSHA regulations for metal/nonmetal mines OSHA regulations for tunnel construction Types of respirators used in mines and tunnels Filter materials and filter efficiencies Donning, seal checking, and maintenance Filter service life and Respirator information resources] In many cases, engineering controls are not adequate to achieve satisfactory dust levels, so respirators must be used. This chapter explains the Federal regulations governing the use of dust respirators in mines and tunnels and describes the most common dust respirators used. Filter materials and filter efficiencies for respirators are discussed. This chapter also gives some guide-lines for respirator use and recommends sources for more dust respirator information. Respirator effectiveness in reducing dust exposure usually exceeds the effectiveness of most engineering control methods. RESPIRATOR REGULATIONS [Different regulations govern respirator use in coal mines, metal/nonmetal mines, and tunnels under construction.] Coal mines under Mine Safety and Health Administration (MSHA) jurisdiction. Coal mine operators are required to meet dust standards using only engineering control methods. Typical engineering control methods include ventilation and water sprays. Respirators are not regarded as an engineering control method, so respirators cannot be used in lieu of engineering controls.

Jan 6, 2003

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

MINE VENTILATION NETWORK ANALYSIS

Jan 1, 1977

By Walter R. Storms, Allan B. Bowman

This paper , which describes mining methods and practices at the Mineral Hill copper mine , is one of a series being prepared by the Division of Minerals of the Bureau of Mines on mining methods , practices , and costs in various mining districts. of the United States . The Mineral Hill mine is situated on the northeastern piedmont of the Sierrita Mountains at an altitude of 3,650 feet in sec . 35 , T. 16 S. , R. 12 E. , and sec . 2 , T. 17 S. , R. 12 E. , Pima mining district , Pima County , Ariz . ( fig . 1 ) . The claims (figs . 2 and 3) are in a gently rolling area with only scant desert vegetation . The average annual precipitation is about 11 inches . The nearest surface water is the Santa Cruz River , an intermittent stream 8 miles east of the mine . The property is owned by the Banner Mining Co. , a Nevada corporation . This report presents a brief history of the mine , describes the geology of the area and the ore deposits , outlines methods of prospecting and exploration , and gives methods of sampling and the estimation of ore reserves and values . Development and stoping methods are explained , and methods of underground transportation , ventilation , mine drainage , and safety measures are described . The concluding section of the paper is a section on milling . The Mineral Hill mine is an old mine that was reopened in 1951 after having been closed for 30 years .

May 1, 1957

By Liming Yuan

[ ]

Jan 1, 2009

By Fred N. Kissell, J. E. Matta, J. C. LaScola

The Bureau of Mines made laboratory absorption measurements on oil shale samples, which showed that the amount of methane absorbed is proportional to pressure and oil yield, and can be much larger than would be predicted based solely on porosity. Oil shale cores collected in the field were also measured for their gas content using the Bureau of Mines direct method, Cores taken from deep locations and far from outcrops yielded more gas than cores from shallower locations or at outcrops, when taking into account variations in oil yield, and all data indicate that oil shale mines that are both deep and far from an out- crop will emit low levels of methane gas.

Jan 1, 1977

By Louis D. Dornetto

The effects of electric shocks on man are an important factor in the design of power systems and protective devices. The current levels just below let-go and just prior to the onset of ventricular fibrillation must be known and taken into consideration in the design of power systems and protective devices. Isolated (ungrounded) electrical distribution systems are compared with resistance and solidly grounded systems. The advantages and disadvantages of each are discussed and recommendations are made. Transients on coal mine power systems are a problem that, until recently, have been ignored. Transient voltage levels that can be expected on both the high and low side of the load center and the effects of transients on electronic equipment and personnel are covered.

Jan 1, 1975

By W. S. Sanner

Grinding experiments were conducted to determine the finest anthracite particles that could be produced in a ball mill. Continuous and batch tests were run in a dry-grinding ball mill. Batch grinding produced the finest coal particles. They averaged 2.2 microns in diameter and were 99.0 percent smaller than 37 microns. Continuous grinding yielded a product 6.1 microns in diameter, with 96 percent smaller than 37 microns.

Jan 1, 1968

By H. H. Hill

"The wide publicity that is given to the discover; of new oil fields has led many people to believe that our supply of crude petroleum is practically in- exhaustible and that in order to keep pace with the demand for petroleum products, it is only necessary to drill a few more wells in some of the south-western states. It is not generally realized that, although many famous fields have been developed in Oklahoma, Kansas, Texas and Louisiana during the past few years, the production of crude oil in 1919 was not sufficient to meet the demand and it was necessary to import approximately 53,000,000 barrels from Mexico.Continued efforts are being made to recover a larger percentage of the oil underground by improvements in methods of drilling and in handling producing properties. Improvements are also being made in methods for handling the oil after it has reached the surface which will result in reducing losses through leakage and through evaporation. These methods for cutting down waste in production and storage, if universally adopted, will no doubt result in appreciable increases in our supply of crude oil."

Nov 1, 1920

By Robert C. Hickman

"INTRODUCTION The Cline mine has been worked intermittently for copper and gold since 1895. Scheelite has recently been detected with the aid of a ""Mineralite"" on the old waste dumps of the mine. Four diamond-drill holes were drilled by the Bureau of Mines from August 13 to September 25, 1946. Results of this drilling showed the vein to pinch at depth and to carry no mineralization of economic importance.ACKNOWLEDGMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, does the actual investigation work, and prepares the final report. The Metallurgical Branch, Oliver C. Ralston, chief, analyzes samples and makes beneficiation tests.The project was under the general supervision of Mitchell H. Kline, chief, Raleigh Division, Mining Branch.Acknowledgment is due Dr. Jasper L. Stuckey, State geologist, for logging the drill core and to J. B. Zadra and associates, Metallurgical Branch, College Park, Md., for analytical determinations."

Feb 1, 1948

By Robert M. Becker

A thick-wall cylinder solution applicable to the evaluation of anisotropic elastic parameters is derived for the interpretation of stress relief data. For a restricted class of problems, a special relationship among certain orthotropic moduli yields stress distributions for the plane orthotropic problem that are identical to the corresponding isotropic case. A ring or hollow cylinder with these specialized anisotropic properties subjected to uniform radial loads is one of the problems in this class. Consequently, known stress solutions are used to develop the strains and displacements for a specialized orthotropic thick-wall cylinder under uniform pressures. The results are consistent with anisotropic equations used in the evaluation of in situ rock stresses.

Jan 1, 1968