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Although alternating-current (a.-c.) power systems and equipment have been used in coal mining for many years, most mines in the United States are powered mainly by direct current (d.-c.). There are several logical reasons for this, but the use of d.-c, equipment is, in most instances, a direct outgrowth of the original practice of using such power for haulage systems. For traction equipment such as the electric trolley locomotive the d.-c. motor has ideal operating characteristics, and thus it has been widely used for haulage locomotive service. The first efforts at electrification of coal mines started with the haulage system and from there branched out to include the many types of electrically powered mining machinery used in the industry today.

Jan 1, 1960

By Parry. V. F., John B. Goodman

"INTRODUCTION The Denver region coal field, covering an area of approximately 7,640 square miles, extends from the Wyoming State line to the middle of El Paso County, Colo. The coal in this region is subbituminous in rank. Much of it is used as domestic fuel. During the last decade the production of coal in this field has remained fairly constant at an average of 2,600,000 tons per year. This production has come from 50 to 60 mines, 88 to 90 percent of the production being from the section of the field north of Denver.According to the Standard Specifications for Classification of Coal by Bank of the American Society for Testing Materials 4/ the coals in this region are classified in the Subbituminous B and C group. On the as—mined basis, they contain about 22 percent moisture and average 9,600 B.t.u. per pound. They are noncoking and slack to a variable extent when exposed to the weather. This is characteristic of subbituminous coals."

Aug 1, 1939

By Kenneth L. Cook

From March 1944 to July 1945 the Division of Geophysical Exploration of the Federal Bureau of Mines made magnetometer surveys of some of the principal iron ore deposits of the Iron Springs district, Iron County, Utah. The district comprises a belt about 23 miles long and 3 miles wide. Most of the large ore bodies are found as pods of replacement ore within a favorable limestone bed lying at the margins of three separate igneous intrusions in the district The magnetic surveys were confined chiefly to this geologically favorable zone at the margins. The iron ore is a mixture of magnetite and hematite. The magnetite content of the ore ranges from 14 to 58 percent. Magnetic anomalies of 1,250 gammas or more were usually found over the near-surface ore bodies. About 62,000 magnetometer stations were taken over a total traverse distance of about 300 miles. Outcropping ore bodies were surveyed to determine, insofar as was possible from the magnetic data, their probable length, width, depth, extent, strike, dip, and tonnage. Geologically favorable areas where no ore is exposed were explored in an endeavor to find new ore bodies. Favorable locations were determined for exploratory diamond drilling, both in areas of exposed ore bodies and in areas of newly discovered magnetic anomalies. Forty-five separate magnetic anomalies that indicate the possible existence of ore bodies were observed. Of these, 13 anomalies are caused by outcropping ore bodies of proved commercial size. Five are caused by non-outcropping ore bodies of proved commercial size which were discovered, in whole or in part, as a result of the geophysical surveys. Of the remaining anomalies, which lie in virtually un-tested areas where few or no ore bodies are exposed, six probably are caused by large, unexposed replacement ore bodies, nine are possibly caused by large, unexposed replacement ore bodies, and six are probably caused by unexposed magnetite veins of some small commercial importance,

Jan 1, 1949

By D. W. Blaylock

1. The Lower Freeport and Lower Kittanning beds are the most important beds in Clearfield County, Pa., from the standpoint of production. The Lower Kittanning bed has the largest remaining recoverable reserves of any of the beds in the county. 2. Known measured and indicated reserves in all beds, based on a minimum thickness of 14 inches and 1,800 short tons per acre-foot of coal in place, are estimated at 1,909 million short tons as of January 1, 1953. Of this total, 1,177 million short tons is in beds 28 inches and more thick. Areas in some beds were omitted from the estimate because available data relative to the bed characteristics are too meager to make an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, such reserves should be added to the total estimated reserves.

Jan 1, 1955

By John J. Henn

An evaluation is presented of the Bureau of Mines process for the recovery of metal and mineral values from municipal incinerator residues. This process employs standard mineral beneficiation techniques and is operating on a pilot-plant scale of 1,000 pounds of incinerator residue feed per hour. Products from this separation process include ferrous, aluminum, and copper-zinc scrap, and colorless and colored glass. Cost estimates were prepared for four plant sizes. The estimated capital and operating costs For the four plants follow: [ ] It is assumed that the separation plant is located adjacent to a municipal incinerator. Provision is made, however, for part of the residue feed to be delivered by truck so that one large separation plant can be used for residue from more than one incinerator.

Jan 1, 1971

Recent Bureau of Mines research in earth grounding safety is documented in three separate papers. First, guidelines for the design of a 5- ohm borehole ground are presented. Next, an inexpensive practical means to construct a low-resistance bed in high-resistivity soil is described. Finally, a procedure that employs a commercial resistivity meter to measure shock potentials around grounded objects is explained step-by-step. These papers complement the material presented at an earlier technology transfer seminar and published as IC 8767.

Jan 1, 1985

By N. Kumar Kittusamy

The purpose of this study was to assess the adequacy of the cab design and to determine the percentage of musculoskeletal symptoms among workers. A questionnaire was designed to assess demographics, work information, job history, and musculoskeletal symptoms in operators of heavy construction equipment. Information concerning equipment included design of the seat/chair, levers, pedals, bothersome vibration, quality of egress from the equipment, proper preventative maintenance and repairs, and age of the equipment. The body regions that were evaluated included the neck, middle/upper back, low-back, shoulder/upper-arm, elbow/forearm, wrist/hand, hip, knee, and ankle/foot. One hundred and eighty nine operators completed the questionnaire. The results indicate that these workers are at risk for developing musculoskeletal disorders, the need to perform a larger survey to further substantiate the outcome, and the need to quantify risk factors (i.e., whole-body vibration and static sitting postures).

Jan 1, 2003

By Vernon O. Markworth

This report contains the results of tests performed on three large diesel engines to determine their ability to meet selected criteria of the Mining Enforcement and Safety Administration Regulations for equipment used in gassy, non-coal mines. Study efforts were first directed toward determining the types of equipment expected to be used in underground oil shale mines. Three typical engines in the 800-1200 horsepower range were then selected for testing. Intake flame arresters, exhaust scrubbers, and water jacketed exhaust system were designed and built for each engine. During testing, each engine was evaluated for its gaseous emissions output, adequacy of the exhaust gas cooling system, ability to withstand internal explosions, and adequacy of the flame arresters. Surface temperatures of the engine and exhaust cooling system were determined under full load operation.

Jan 1, 1978

By Chas. F. Jackson

The work of the Mining Division is divided among seven sections, each in charge of a supervising engineer, as follows: 1. Metal-mining methods section, the supervising engineer of which is also supervising engineer of the Southwest Experiment Station at Tucson, Ariz. 2. Metal-mining research section. 3. Nonmetal-mining section. 4. Coal-mining section. 5. Mine-ventilation section. 6. Mineral-industries survey section. 7. Electrical section. The names of the sections indicate broadly the fields covered by each, and in the following, pages the objectives and type of work of each section will be summarized briefly and their active problems listed. The work clone during the fiscal year 1937 will also be summarized.

Jan 1, 1937

Surface mining and reclamation of a southeastern Ohio site with sandstone-shale overburden resulted in (as compared to premining levels): 1) runoff volumes and peak rates that increased by a factor of from 2 to 10 during mining and after reclamation, 2) destruction of the "aquifer" perched on the underclay of the mined coal bed and gradual, but, as yet incomplete redevelopment of this aquifer after reclamation, 3) no immediate effect on another, lower perched "aquifer", 4) up to 100 times greater sediment concentrations in runoff. Results were influenced by increasing annual precipitation amounts through the period of record; 1978, 1979, and 1980 (postreclamation years) experienced precipitation amounts approaching or exceeding long-term normalcy for the area. Part of the reason that the site produced more runoff after reclamation than before mining is that the premine condition was one of an open, porous soil under woodland, while the postreclamation condition was one of a compacted, bulldozed soil. Sediment concentration results were influenced by failure of the postreclamation erosion control system and by a series of detention reservoirs above the stream monitoring station.

Jan 1, 1983

By T. A. Lang

The objective was to develop a Program Plan of analytical studies and tests for determining ( 1) the optimum installation tension of a coal mine roof bolt, (2) the most valid bolt support theory or theories, and ( 3) the most valid roof failure theory or theories. On this basis a comprehensive literature search was made and significant material dealing with coal mine roof behavior, roof bolting and roof support was collected, reviewed, classified and analyzed. Emphasis was given to the influence of rock reinforcement on the control of deformation, stress field modification and mine roof stability. An assessment was made of the effect of various parameters including bolt tension, bolt pattern and time of installation, on the effectiveness of rock reinforcement systems, and equations developed for bolt tension as a function of these parameters, and rock properties. From these studies, a major program plan of tests and studies was developed for verifying and validating the most tenable theories of roof behavior and roof support and for determining optimum bolt installation tension.

Jan 1, 1979

By H. E. Harris

An extensive experimental program was carried out to determine the variability of respirable dust samplers and to determine whether area dust sampling is feasible in coal mines. For sampler variability, it was found under laboratory conditions, that a single dust measurement could be as much as 0.30 mg/M3 from the true value at the 95% confidence level. Under actual underground mining operations, this difference could be as much as 0.52 mg/M3 in the 0 -5.0 mg/M3 range. The results from dust sampling on 175 production shifts involving over 2,500 on-man and area dust samples showed that area sampling is viable, but the field investigation did not establish necessarily where the best area locations were.

Jan 1, 1976

By James J. Dowd

The investigation to evaluate the reserves of coking coal in the United States suitable for the manufacture of metallurgical coke is being made by the Bureau of Mines in three parts: (1) To estimate known (measured plus indicated) recoverable reserves of all coking coal; (2) to upgrade marginal coals through effective preparation; and (3) to study the carbonizing properties of coals and coal blends not now widely used for metallurgical coke making. This is the sixth of a series of reports giving the results of studies by counties under part (1) of the investigation. (See appendix.) This report covers Fayette County, Pa., which comprises the Uniontown and parts of the Brownsville, Connellsville, Donegal, Waynesburg, Masontown, and Confluence, Pa., Morgantown and Bruceton, W. Va., and Accident, Md., quadrangles. (See fig. 1.) A short resume of the chemical and carbonizing properties of the coals ar.9 included. Data on the coal beds in this county were obtained from mining companies, land companies, individual landowners, and other sources of authentic information.

Jan 1, 1951

By Rolland L. Blake

Petrographic methods of examination were used by the Bureau of Mines on a suite of samples of ultramafic rock from Soapstone Ridge, Ga., located about 8 miles south-southeast of Atlanta. The samples were analyzed to determine (1) their potential for releasing regulatory particles upon crushing and grinding and (2) their concentration of fibrous particles that approach the dimensions of amphibole and serpentine asbestos minerals. Such particles might be generated during grading and excavation for housing and industrial development and could become a health concern. Light optical microscopy, scanning electron microscopy, and X-ray diffraction were the techniques used to examine the samples. Six of the twelve samples contained amphibole as a major mineral; in five, it was a moderate to minor mineral. One sample contained no amphiboles, and serpentine was not observed or identified by X-ray diffraction in any of the samples. In nine of the samples, the amphiboles exhibited a habit that was either prismatic or acicular, but not asbestiform. Two of the samples did contain asbestos, occurring as small veins or fracture fillings, which represented only a minor percentage of the total sample. Similar petrographic screening is recommended for examining any rock deposit or mine location to delineate hazardous and nonhazardous mineral areas.

Jan 1, 1982

By S. H. Ash

THE MAGNITUDE of the anthracite industry's drainage problem in the Lackawanna River drainage area is realized when it is known that in 1948 the 27 pumping plants in this region pumped over 48 billion gallons of water to the surface from the mines in the Lackawanna Basin of the Northern field. This is almost 92,000 gallons per minute pumped against an average hydrostatic head of over 300 feet for that year. By comparison, Lake Wallenpaupack, the largest artificial body of water lying wholly in Pennsylvania, contains 71 billion gallons of water in its 24-square-mile area: the volume of water pumped from the mines in the Lackawanna Basin during 1948 was approximately 68 percent of that impounded in Lake Wallenpaupack. The Lackawanna. River and its tributaries drain a troughlike area of 345 square miles. The synclinal axis of this trough lies within the coal measures. All surface drainage into the valley must traverse some part of the coal measures. On the basis of 45.03 inches of rainfall recorded by the Scranton station of the United States Weather Bureau for 1948, the runoff from the Lackawanna River drainage area during that period was 135 billion gallons, approximately three times the volume of water pumped by all mine pumping plants in the Lackawanna. Basin of the Northern field during 1948. In other, words because of the pervious condition of the strata overlying the mine workings, approximately one-third of the total runoff in the Lackawanna River drainage area becomes mine water. This report, reveals that less than 7 percent of the 72 miles of pervious stream beds examined between Archbald and Pittston have been unproved.

Jan 1, 1952

By J. F. Barkley

[There is a general concept in the, coal trade that the moisture- and ash-free B.t.u. of coal from the same seam, and. surely from the same mine, is substantially a constant; that calculation of the -moisture- and ash-free B.t.u. value from the proximate analysis and B.t.u. determined in the laboratory will reveal whether a coal came from a given area or sears; and that, having this constant, the B.t.u. value of a coal sample can be calculated fairly closely upon a dry or as-received basis from the moisture and ash values of its proximate analysis.]

Jan 1, 1941

By E. L. Garton

Bureau of Mines routine crude-oil analyses of 88 samples from 60 fields are presented in this report. Similar analyses from other fields in California have been published in previous reports listed in the appendix, page 52. Yearly production of crude oil in California and the percentage of United States production represented by California production for 1948-54 are given in table 1. [ ] Analyses in this report are of samples from the fields listed in table 2, with production data for 1953, cumulative production through 1953, and year of discovery of each field. Information regarding the source and general characteristics of the samples is included in table 3 with a summary of analytical and computed data.

Jan 1, 1956

By John J. Henn

Ten proposed processes for the recovery of manganese from domestic resources as a high-grade oxide product are described. Nine of the processes employ sulfur dioxide, sulfuric acid, or a combination of both for leaching. The tenth process utilizes sulfur dioxide to sulfatize the ore at 600° to 850°C before water leaching. In addiction to these ten complete processes, six processes from the patent literature are described. Methods for receovering MnSO4?H2O are also reviewed.

Jan 1, 1968

By Robert M. Koerner

The feasibility of using small-scale models to simulate residential masonry foundation walls subject to fatigue loading was investigated. Five wall segments were modeled in one-quarter scale using dynamic similitude equations. The walls were dynamically loaded using a sinusoidal base motion and wall accelerations were monitored. The stiffness, natural frequency response, and damping characteristics were measured. The number of cycles of testing necessary to cause initial visible cracking was recorded. Analysis of the data indicated the importance of the relationship between the forcing function and the natural frequencies of the structure in influencing cracking damage.

Jan 1, 1980

Nineteen eighty-seven was a year of significant change in the Bureau of Mines-change to help it better adapt and respond to the wide range of new challenges facing the U.S. mineral industry. The Bureau has been regarded as the world's premier mineral information and research agency. Its authoritative, comprehensive data and its pioneering research have contributed significantly to the minerals position of the United States. Yet no organization in today's complex, dynamic world, with its rapidly advancing technologies, can afford to rest on its laurels. Mission and program must be constantly fresh and relevant to the day's issues and problems. Moreover, rather than reacting to events, the organization must strive to anticipate and prepare for them. It must have a sense-a vision, if you will-for the future.

Jan 1, 1987