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By M. G. Zabetakis

Benzene and toluene are the first two members of an important homologous series whose general formula is CnH2n-6. The members of this series differ in composition from benzene by some integral multiple of CH2; they can all be prepared in the laboratory by the Wurtz-Fittig, Friedel-Crafts and Grignard syntheses. Because 'of the industrial importance of these-hydrocarbons, the limits of flammability of eight members of the series have been determined at 100° C.-(A temperature of 1000 C. was chosen because the determination of the upper limit of flammability of p-cymene requires an apparatus temperature. of at least 90° C. As elevated temperature data are available for other combustibles at 100° C. but not at 90° C., all data were taken at 100° C. in order to obtain comparable results.) Minimum ignition temperatures of these combustibles have been determined at laboratory-pressures.

Jan 1, 1951

By E. E. Maust

The present work is part of an ongoing Bureau of Mines effort to provide a better understanding of the fundamental phenomena involved in sulfide flotation, the role of oxygen in xanthate adsorption being one essential issue. Galena was chosen as the material around which to develop a conceptual model, partly because of its demonstrated oxygen sensitivity and partly because information on its properties and flotation behavior constitutes the largest part of the fundamental information available on sulfides of commercial importance. The model is formulated primarily in terms of surface electronic energy levels produced by oxygen and xanthate and is further developed using existing experimental evidence and its implications. Four major functions of oxygen are elucidated, and the relationship of these to the formation of lead xanthate, dixanthogen, and a surface compound is discussed. Though yet incomplete, the model provides a useful framework within which the results of diverse experiments can be related to one another in their proper perspective, as shown by a brief discussion and resolution of some apparently discordant results reported in the literature.

Jan 1, 1976

By Gordon Bath

During the summer of 1946, the Division of Geophysical Exploration of the U.S. Bureau of Mines established several primary magnetic base stations near important iron-producing districts in Minnesota, Michigan, and Wisconsin. Stations were located in groups of four to six in six separate base-station areas, and each position was marked with a concrete monument. Differences in magnetic intensity between stations in these areas, as well as the difference between each area and a magnetic datum at the magnetic observatory of the Coast and Geologic Survey at Cheltenham, Md., were measured with a modified Askania magnetometer. Measurements also were made with a Hotchkiss superdip to study the usefulness of the stations for the calibration of instruments of this type. The work was planned and supervised by F. W. Lee, chief of the Division of Geophysical Exploration, and Edward F. Fitzhugh, Jr., chief of the Minneapolis Division of the Bureau of Mines. Special mention is due Harold B. Ewoldt, Bureau of Mines engineer, for his assistance in the field work, especially in locating and establishing monuments. Special mention also is due Clyde L. Holmberg, of the Bureau of Mines, for the magnetic measurements made with the Hotchkiss superdip. Helpful suggestions were received in the field from H. L. James, of the U. S. Geological Survey. Acknowledgment is made of the cooperation of Stephen Royce, Irving E. Beckwith, Arthur Johnson, and Josiah Royce of Pickands, Mather & Co., and A. E. Matson, of Butler Bros. The U. S. Coast and Geodetic Survey furnished daily magnetograms from the Cheltenham Magnetic Observatory as well as calibration equipment and values of absolute magnetic intensity. Short-term forecasts of ionospheric conditions were obtained from the National Bureau of Standards.

Jan 1, 1951

By Charles N. Speltz

Coal resource data from public and private sources, in conjunction with previously published data, were used by the Bureau of Mines to determine the location and extent of strippable coal resources in Colorado. Total strippable resources of approximately 18 billion tons were estimated in 12 separate coal regions, fields, or deposits. Coal recoverable by contour mining techniques was not included. Criteria used in defining strippable resources were a minimum coalbed thickness of 2 feet and a maximum overburden thickness of 150 feet, except where the coalbeds are of exceptional thickness. Ail Colorado coal is either Cretaceous or Tertiary in age. Cretaceous coals occui In the Dakota Sandstone, the Mesaverde Group, and equivalent formations while Tertiary coals occur in the Dawson Arkose, the Fort Union and the Wasatch Formations, and equivalent formations. The strippable coal ranges in rank from bituminous in the Yampa region to ligniferous in the Denver basin. Ali this coal is low in sulfur content (less than 1 percent); ash content is low to high; heating value ranges from 3,000 to 12,000 Btu's per pound. Ash from the lignite of the Denver basin was found to contain an abnormally high percentage of kaolinite which conceivably could be recoverable as alumina.

Jan 1, 1976

By Jr. Gabler

Because of concern over the availability and reliability of an uninterrupted supply of manganese and other materials, the U.S. Congress requested that the U.S. Bureau of Mines (USBM) study the /low of strategic and critical materials in the economy to delineate and quantify the production areas where metal values are lost. As a result, the USBM developed a generic computerized commodity flow model that is readily amenable to updating. The original model developed for cobalt, with slight modifications, was used to track the flow of manganese. This report follows the flow of manganese through its metallurgical and chemical applications and highlights areas where significant losses occur owing to downgrading, export, or disposal. The study indicates that materials containing 695,000 short tons (st) of manganese were consumed domestically in 1990. Scrap recovery specifically for manganese recycling was insignificant. However, considerable manganese was recycled through processing operations as a minor component of ferrous and nonferrous scrap and steel slag. The major loss category is manganese lost in steel processing, 323,156 st or 46 pet of the 1990 apparent consumption. Most of this loss reports to steelmaking slags. Recovery from slags is technically feasible, but is not economically feasible.

Jan 1, 1995

By W. E. Robinson

Oil-shale kerogen was processed into oil and oil products before the first oil well was completed by Drake in 1859. However, because of economic and other advantages, natural petroleum has been the principal source of liquid fuels and lubricants since 1859 and is a convenient root of many [organic] chemicals in common use today. In recent years the difference has narrowed between the cost of producing liquid fuels from well petroleum and other sources. This narrowing of cost difference has resulted both from the increased cost of finding new sources of petroleum in the United States and the experimental demonstration of lowered costs for synthetic liquid fuels by the Federal Bureau of Mines and by industry. Available petroleum resources of this country are being reduced and eventually may be inadequate to meet the demand. Alternate means of assuring an adequate supply of liquid fuels for this country include the development of processes for utilizing other carbonaceous materials such as oil shale and coal.

Jan 1, 1960

By Bruce T. Olenchuk, Wils L. Cooley

Electrical grounding is essential for the safe operation of power systems. A low-impedance path to ground is necessary to prevent the possibility of dangerously high potentials in human work areas. If for any reason this ground connection becomes faulty, a serious hazard may exist. One reason for faulty ground connections is ground bed corrosion. Corrosion of electrical ground rods has plagued the power industry and appeared in coal mine power systems. This paper will investigate ground rod corrosion, its cause, and possible solutions. Included is an evaluation of various ground rods for their ability to resist corrosion under stray current conditions. -The first known study of X-it3 Rod Corrosion is also presented.

Jan 1, 1979

By Kenneth L. Cashddollar, Terry G. Montgomery, Eric S. Weiss, John E. Going

The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) and the Mine Safety and Health Administration (MSHA) conducted joint research on dust explosions by studying post-explosion dust samples. The samples were collected after full-scale explosions at the PRI, Lake Lynn Experimental Mine and after laboratory explosions in the PRL 20-L chamber and the Fike 1-m3 chamber. The dusts studied included both high and low volatile bituminous coals. Low temperature ashing for 24 hr at 515°C was used to measure the incombustible content of the dust before and after the explosions. The data showed that the post-explosion incombustible content was always as high as or higher than the initial incombustible content. The MSHA alcohol coking test -was used to determine the amount of coked dust in the post-explosion samples. The results showed that almost all coal dust that was suspended within the explosion flame produced significant amounts of coke. Measurements of floor dust concentrations after LLEM explosions were compared to the initial dust loadings to determine the transport distance of dust during an explosion. All of these data will be useful in future forensic investigations of accidental dust explosions in coal mines or elsewhere.

Prevent the explosion of methane gas or coal dust by replacing air with inert gas inside highwall mine excavations. Approach Use combustion gases as a source of inert gas with low oxygen content to blanket the cutting, head of highwall mining machines. This gas is placed strategically at the collar of the excavation where it enters the hole to replace the mined coal volume. The elimination of oxygen from the hole prevents explosions of gas or dust. How It Works Highwall mining methods arc used when surface mining becomes uneconomical. One method of highwall mining involves use of a horizontal auger to enter the coalbed from a surface mine bench. The coal is mined in a series of horizontal, parallel, and large-diameter holes. Historically, little methane has been associated with auger mining. However, mining technology has extended the reach of auger mining, which can increase the occurrence of methane. Methane explosions at auger mining operations have been increasing. Methane has been the primary fuel source of these ignitions, but coal dust also may have been involved.

Jan 1, 1993

By John E. Pahlman

The Bureau of Mines investigated the feasibility of removing heavy metals from mineral-process waste streams by precipitation with lignochemicals and humic acids. Lignochemicals are by products from the paper industry, while humic acids are obtained by caustic treatment of peat, subbituminous coal, and lignite. These high-molecular-weight organic materials have many functional groups, which can coordinate and form innercomplex salts with heavy metals that are crystalline precipitates. Filtering of a humic-acid-or lignochemical-treated solution or waste stream containing these precipitates removes the heavy metal sequstrates. Tests were conducted with two lignochemical samples, three humic acid samples, lime (CaO), and sodium hydroxide (NaOH) in which increasing amounts of these additives were reacted with 50 mL of solution containing Fe3+ , Al3+, Cr3+, Pb2+, Cu2+, Cd2+, Zn2+, Co2+, Ni2+, Mn2+, and Hg1+. At the appropriate pH, greater than 90-and 99-pct removal was achieved for these 11 heavy metal ions from the 10-and lOO-ppm solutions, respectively, using lignochemicals and humic acids. Removal efficienC)' with these organic materials is better than that with CaO, especially for the more toxic ions, Hg1+, Cd2+, and Pb2+. Unlike the precipitates formed with NaOH or CaO, those with lignochemicals and humic acids are compact and noncolloidal. The volume of their sludge is sharply lower than that of the finely dispersed lime or soda precipitates; thus, their removal in settling tanks or by simple filtration is enhanced.

Jan 1, 1988

By H. C. Brunaugh, James Westfield, R. W. Whittaker

"INTRODUCTION The purpose of this circular is to describe the sealing off of a mine fire and subsequent use of carbon dioxide gas to extinguish it.A fire of electrical origin occurred in the Valier mine of the Valier Coal Co., Valier, Franklin County, I11., on March 29, 1949, at about 1:35 p.m. It was discovered about 3:35 p.m. in 5 south west intake airway inby 1 and 2 west panels. The No. 5 southwest airway had caved, and the fire was in the top coal beneath a large fall of rock. All men, except officials, were ordered from the mine. The mine officials decided to seal the fire, and four temporary seals were erected, which isolated approximately 200 feet of 5 south west entry. The seals were completed on March 30 at 2:45 a.m., but on March 31, at 3;40 a.m,, two of them were blown out by an explosion of gas that was produced by the fire. The two seals were rebuilt, the work being completed on March 31 at 12:00 noon, but they were blown out by another gas explosion at 12:10 a.m. on April 1. It was then decided to extinguish the fire with water if possible.To accomplish this, concrete-block dams were constructed. On April 1, about 4:25 a.m., when the dams were about half completed, water was introduced into the fire area through a 2-inch pipe.On April 4, J. G, Crawford, general manager of the Valier Coal Co., notified James Westfield, chief of the Vincennes (Ind.) Branch, U. S. Bureau of Mines, by telephone of the fire in Valier mine and requested assistance to combat it. Westfield, accompanied by F. J. Smith and H. C. Brumbaugh, Federal coal-mine inspectors, went underground and inspected the seals and dams. Later, during a conference with company officials, it was decided that the concrete-block dams were not strong enough to withstand the hydrostatic pressure that would be produced by flooding the fire area. It was then decided to use carbon dioxide gas to extinguish the fire. Four seals were completed, and 5 tons of carbon dioxide gas was introduced into the fire area, which extinguished the fire."

Apr 1, 1950

This report contains the papers presented at the Technology Transfer Seminar on Ground Control Aspects of Coal Mine Design held by the Bureau of Mines on March 6, 1973, in Lexington, Ky. Seminar attendance consisted of representatives from the coal mining industry, universities, mining consultants, instrument manufacturers, and local, State, and Federal Government. The purpose of this meeting, one of a series of Technology Transfer seminars, was to provide the coal mining industry with detailed information about recently developed techniques, equipment, and instruments which can be used in the solution of coal mine design problems and to discuss results and direction of research in mine design. The report includes opening remarks by Joseph J. Yancik, Acting Assistant Director--Mining; an overview of the Federal Bureau of mines approach to mine design; three papers an problems associated with the design of panels; five papers on coal mine roof problems; three papers on long wall problems; and the comments made by- the participants on the Bureau-industry panel discussion.

Jan 1, 1974

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

By C. W. Sill

[In the original Norris and Fay method for determining selenium, selenious acid is reduced by an excess of standard thicsulfate in accordance with the following reaction: H2Se03 + 4Na2S203 + 4HC1 = Na2SeS406 + Na2S406 + 4NaC1 + X20. (1) The excess thiosutfate is then back-titrated with standard iodine solution. The disadvantages of ouch a method are obvious. On an unknown sample, the quantity of thiosutfate required would be difficult to determine; a definite excess is required, but large back titrations would be undesirable. Inasmuch as thiosulfate is decomposed by acid, considerable error may be introduced in this method, the amount depending on the acidity, temperature, concentration of excess thiosulfate, duration of contact between thiosulfate and acid, and other factors, In a critical study of the Norris and Fay method, Coleman and McCrosky3/ show that the method is accurate to less than .1 part per thousand if the excess of this sulfate Is not greater than 5 ml. of 0.1 N solution (in 1.0 ml. of 0.x4 N sulfuric acid) whether the titration is made at 0° or 20°C. A greater excess produced unsatisfactory values at either temperature. Coleman and McCrosky regulated the excess thiosulfate by adding 5-ml. portions of thiosulfate solution followed by the addition of 1 to 3 drops of 2.5 percent potassium iodide in the presence of starch. If a starch-iodine blue color formed locally around the drops of potassium Iodide, the reduction of selenious acid was not complete. On stirring the solution, the local blue color fades and another 5-ml. portion of thiosulfate is added. When addition of potassium iodide fails to produce a local blue color, reduction of selenious acid is complete, and the excess thiosulfate is then back-titrated with standard Iodine solution. The number of equivalents involved in the reduction of selenious acid by either thiosulfate or iodide is the same, and therefore no correction need be made for the potassium iodide. This procedure is much better than the original Norris-Fay titration, but acidity and time would stilt be rather critical factors subject to variation with individual technique. Also, the method still requires the lose of two standard solutions, a rather undesirable factor from the standpoint of routine application.]

Jan 1, 1954

By D. A. Reynolds, J. D. Davis

"INTRODUDTION Investigations by the Bureau of Mines have shown that the carbonizing properties of splint and bright coals may differ greatly. In a study of 55 coal columns selected from representative coals of the Appalachian region, Sprunk and coworkers 10/ compared various chemical and physical properties of splint and associated bright coals. Carbonization tests in the Fischer retort at 932°F. (500°C.) showed that, except for bright coals of high oxygen content, the coke residue from bright coal was much more swollen and cellular than that from splint. ·with one exception, agglutinating values determined by the Bureau of Mines test, were lower for splint than for associated bright coal.Because sorting of coal in quantity is tedious and time-consuming, separate types have not been carbonized by the Bureau of Mines-American Gas Association (BM-AGA) test, which requires 85- to 200 pound charges. However, this method has been used to determine the carbonizing properties of samples 0f bed layers that are composed largely of either splint or bright coal.4/ In these earlier tests, which were made at high temperatures on layer samples from the Elkhorn bed, Letcher County, Ky., the splint coal yielded more coke than the bright coal, and this coke was slightly stronger than that from the bright coal. The cokes from samples with large proportions of bright coal were more cellular or porous, as were the low-temperature cokes obtained from carbonization of separated samples of bright coal in the Fischer retort."

Apr 1, 1944

By Th. G. Sahama

This paper contains some new thermodynamic data for silicates in the series Mg2SiO4-Fe2SiO4 and MgSiO3-FeSiO3 and Lives the result: of a thermodynamic attack on the problems of stability end paragenoses. Although some data are lacking, satisfactory agreement with mineralogical and petrological observations is indicated.

Jan 1, 1949

By H. F. Weaver

The 19th National First-Aid and Mine Rescue Contest was held in the Civic Center, Charleston, w. Va., on October 2, 3, and 4, 1961. The meet was sponsored by the Bureau of Mines and the Joseph A. Holmes Safety Association, in cooperation with State mine inspection agencies, management and labor of the mineral extractive industries, and other groups interested in safety. The Arrangements Committee, as authorized by the General Committee, made the necessary arrangements for conducting the 1961 contest. Members of the Arrangements Committee were: George Trevorrow (chairman), Bituminous Coal Operators' Association; James B. Benson, Southern Coal Producers' Association; Charles Ferguson, United Mine Workers of America; Harry Gandy, Jr., National Coal Association; and James Westfield, Bureau of Mines.

Jan 1, 1962

By Peter H. Toepfer

This report presents the factual data obtained by the Bureau of Mines during diamond-drilling investigation of the Sunset copper deposit in the Index mining district, Snohomish County, Wash. The Sunset mine, first produced copper ore in 1902, but its main period of activity was from 1923 through 1930, The mine has produced 263,500 tons of ore, from which 1,500 ounces of gold, 156,000 ounces of silver, and 12,912,000 bounds of copper-were recovered. The mine has, been idle since 1946

Jan 1, 1953

By W. W. Adams

[Sales of explosives - permissible explosives5/ other high explosives, and black blasting powder - in the United States during the calendar year 1937 reached a combined total that slightly exceeded the quantity sold in 1936. A larger output was reported for permissible and other high explosives but a smaller for black powder. Production of the three classes of explosives totaled 404,744,294 pounds, more than 3 percent over 1336. The total quantity produced included 49,579,441 pounds of permissible, 288,924,253 pounds of other high ex- plosives, 36,403,950 pounds of black powder in pellet form, and 23,836,550 pounds of black powder in granular form. Sales of granular black powder declined 26 percent compared with 1936 and of pellet black powder 12 percent; gales of permissible explosives increased nearly 4 percent and of other high explosives 10 percent]

Jan 1, 1938

By Donald J. Keefe

The Remote Working Level Monitor (RWLM) is an instrument used to remotely monitor the Rn-daughter concentrations and the Working Level (WL). It is an ac powered, microprocessor based instrument which multiplexes two independent detector units to a single central processor unit (CPU). The CPU controls the actuation of the detector units and processes and outputs the data received from these remote detector units. The remote detector units are fully automated and require no manual operation once they are set up. They detect and separate the alpha emitters of RaA and RaC' as well as detecting the beta emitters of RaB and RaC. The resultant pulses from these detected radioisotope; are transmitted to the CPU for processing. The programmed microprocessor performs the mathematical manipulations necessary to output accurate Rn-daughter concentrations and the WL. A special subroutine within the program enables the RWLM to run and output a calibration procedure on command. The data resulting from this request can then be processed in a separate program on most computers capable of BASIC programming. The calibration program results in the derivation of coefficients and beta efficiencies which provides calibrated coefficients and beta efficiencies.

Jan 1, 1977