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By Jack Kadlecik

This final technical report describes the concept feasibility study, testing, design and development effort which went into. The quick opening enclosure access cover and flame path tolerance checking system. A detailed definition of the explosion-proof multiple start threads is shown for two (2) sized electrical enclosures.

Jan 1, 1972

By D. Harrington

When the word "gas"' is mentioned in connection with mining almost invariably it is inferred that the explosive gas, methane, is in mind and that the reference is to coal mining. Although methane is likely to occur in any coal mine the metal mines of the world contain by far a greater variety of gases than do the coal mines. Often the gases in metal mines are as dangerous as the gases likely to be found in coal mines, and sometimes are even more deadly. A coal mine is more likely to contain methane than a metal mine. In rare instances it may contain high percentages of nitrogen or carbon dioxide or it may be deficient in oxygen where the air is confined in a blind end or in a sealed region. Much more rarely relatively small percentages of ethane or other hydrocarbons with an odor of ether, gasoline, or kerosene, or minute percentages of hydrogen sulphide are found in a coal mine. During a coal-mine fire or explosion carbon monoxide content is likely to be high (4 per cent or more), and if the coal contains much sulphur the high fumes may contain some sulphur dioxide.

Jan 1, 1931

By S. H. Lorain

Mechanized dirt-moving equipment has greatly increased the scope of prospect trenching by lowering the costs and increasing the speed of such work. Where the soil covering was more than 3 or 4 feet deep, operators were quickly discouraged and abandoned surface exploration in favor of shaft sinking, drifting, or diamond drilling; wildcat trenching was seldom undertaken, even where the soil covering was thin. Although power shovels, trench diggers, and draglines are useful under special conditions, caterpillar-mounted angledozers will usually do the same type of work and have a far wider range of adaptability. They are therefore incomparably the most generally useful equipment for the purpose. Since 199 the Bureau of Mines has been engaged in a widespread search for minerals useful to the war program; this work required a great deal of pioneer exploration in areas where known outcrops were marginal or subcommercial by pre-war standards. Engineers in charge of field operations were quick to perceive the applicability of mechanized trenching on a fairly large scale, particularly in the Northwestern States, where completely exposed vein-outcrops are rare. Probably no other organization to date has done a comparable amount of angledozer prospect trenching under such a wide range of conditions. The following comments and accompanying cost tables are based on work performed chiefly in Idaho, under a variety of physical and climatic conditions. The most important applications of the angledozer for such work may be described under three heads:

Jan 1, 1944

The U.S. Bureau of Mines conducted a laboratory study to determine what effect use of water-jet-assisted cutting has on frictional-ignition suppression. A single bit with a steel tip, installed on a rotating drum, repeatedly made 22-in-long cuts in a block of Berea sandstone. The drum was operated in an enclosure that contained an explosive methane-air mixture. High-pressure front-mounted water jets operating at 2,000 to 5,000 psig and low-pressure rear-mounted sprays operating at 80 psig were used; the number of ignitions that occurred with each type of spray was compared. The rear-mounted spray was more effective for preventing frictional ignitions than the front-mounted water jet.

Jan 1, 1989

By Michael M. Hamilton

In 1984 and 1985 the U.S. Bureau of Mines performed a mineral survey of the South Jackson Mountains Wilderness Study Area covering 60,211 acres of mountainous terrain of Humboldt County in northwestern Nevada. Approximately 550 lode claims have been located within or adjacent to the study area from 1900 to the present. Total recorded production for the area is 28.19 ounces gold, 1,105 ounces silver, 959 pounds copper, 6,016 pounds lead, and 12,446 pounds zinc; an additional two carloads from one mine contained an unknown amount of metal. In early 1986, there were eight active properties with a total of 126 claims. Wescord Resources and Long Lac Exploration (Texas) Inc. are involved in a joint exploration of the Jackson Mountains for volcanogenic massive sulfide deposits. Development at the Claudia mine continues in 1986. Results of the survey indicate that there are no identified mineral resources or reserves within or adjacent to the study area. Twenty-two properties have mineral occurrences containing gold, silver, copper, lead, zinc, iron, antimony, vanadium, and cobalt, with silver, copper, and iron being the most abundant.

Jan 1, 1987

[Determine how subsidence resulting from underground coal mining affects surface structures, and evaluate the usefulness s of the tiltmeter for monitoring foundation movement. Approach The Bureau of Mines is studying foundation response to mine subsidence in order to determine how subsidence-induced ground movements affect foundations in place directly above the mint. These investigations are essential if economic mitigation and repair techniques are to be made. In addition, commercially available tiltmeter are being evaluated (or use as a cost-effective monitoring technique. To study foundation response and to evaluate the tiltmeter system, full-scale model foundations were constructed, instrumented, and monitored for three years. Vertical and horizontal displacements, tilt magnitudes and directions, and observed damages were recorded. Displacements were compared with measured lilt to determine if the tiltmeter was tracking foundation response to subsidence, The Bureau developed a computer software package to aid in the reduction and analysis of the tiltmeter data.]

Jan 1, 1988

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 1973 figures because adequate world information was not available beyond that date. Moreover, 1974 was an anomalous year with respect to prices, supply, and demand for many commodities. 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, 1975

By Wesley T. Holmes

This report describes the first phase of an investigation aimed at obtaining a wider knowledge of the problems involved in smelting titaniferous magnetites. Liquidus temperature measurements were made on selected slag compositions in the titania-alumina-silica-calcia-magnesia system. Both the melting-holding-quenching method and the hot-stage microscope method were used in the tests. Liquidus temperatures of slags studied ranged from 1,217° to 1,667° C. The lowest liquidus temperature of the slags occurred when the difference between CaO plus MgO and Si02 was less than 12 weight-percent. Liquidus temperatures were also lowered when Si02 was substituted for Ti02 plus Al2O3 when CaO and MgO levels were held constant. Improved methods for the measurement of liquidus temperatures on very small samples are described.

Jan 1, 1968

By Bradley V. Johnson

This publication summarizes the in-house and contract research and development projects conducted since 1974 by the Bureau of Mines for the control of noise and vibrations from surface mine blasting.

Jan 1, 1982

By R. Barany

In this paper, closed expressions have been obtained for the frequency spectrum of a Born-Karman square lattice in terms of elliptic and hyperelliptic integrals. This work is part of continuing research by the Bureau of Mines with the thermodynamic properties of metals and minerals. Although other workers have obtained various types of approximations for the general case of the frequency spectrum of a square lattice, no one previously has obtained closed analytic expressions for this spectrum. To understand the optical and thermodynamic properties of crystals, several investigators have studied the distribution of frequencies of normal modes of vibration of the crystal lattice. Born and Karman3 laid the foundation for the theory of lattice dynamics and obtained detailed results for the case of a one-dimensional lattice. Blackman4 used numerical techniques to estimate the frequency distribution of a two-dimensional square lattice. Mbntroll5 analytically determined the frequency distribution of a square lattice for a particular value of the force constants. He also studied the more general problem and obtained some analytic approximations, using the method of moments. However, the calculations by this method were so difficult that it was not always practicable to carry them out. Van Hove6 and Montroll7 studied the nature of the singularities in the frequency spectrum of both a two and

Jan 1, 1962

By Mark Sheppard

The technical literature on the general subject of crushing contains many references to the work of investigators on the laws governing, and the factors entering into, the economical production of fine materials. In fine grinding, whether for the purpose of producing fine material, or for the unlocking of minerals in an ore, close control of the screen sizes of primary-crusher products is of secondary consideration and accordingly has received very little attention. The growth and development of the nonmetallic industries, however, have drawn more attention to primary crushing. Many of these industries are interested in the production of relatively coarse products that meet certain definite size specifications, a condition entirely different from that existing in the field of ore dressing. Under such conditions, a knowledge of the factors governing the selection and operation of primary-crushing equipment is essential to the economical production of a satisfactory material.

Jan 1, 1939

By James A. Wasson

This report summarizes the results and conclusions reached by various investigators who have attempted to determine the extent to which hydraulic fracturing will affect the secondary recovery of crude oil by waterflooding. It also discusses the most advantageous use of this well-stimulation method in waterflood projects. A thorough search of the literature was made, and pertinent information was abstracted from appropriate reports. A carefully designed and controlled program of formation fracturing is an effective aid in waterflooding because it increases water-injection and oil- production rates. Generally, fracturing has resulted in little or no reduction in ultimate oil recovery, but under certain circumstances recovery has been substantially increased.

Jan 1, 1963

By T. C. Woo

This report describes the program that studied the theoretical and practical aspects of the belt cleaning systems, investigated-the possibilities of a self-replacing and/or sell-adjusting belt cleaning device, and designed a horizonal pentagonal turret setup for the underground mine belt conveyors. This design resulted from comprehensive literature survey (both academic and commercial), actual mine visits, study of the mechanics of belt cleaning and bench-type experiments. It has complete working drawings and rough cost estimates.

Jan 1, 1977

By Mark Sheppard

The technical literature on the general subject of crushing contains many references to the work of investigators on the laws governing, and the factors entering into, the economical production of fine materials. In fine grinding, whether for the purpose of producing fine material, or for the unlocking of minerals in an ore, close control of the screen sizes of primary-crusher products is of secondary consideration and accordingly has received very little attention. The growth and development of the nonmetallic industries, however, have drawn more attention to primary crushing. Many of these industries are interested in the production of relatively coarse products that meet certain definite size specifications, a condition entirely different from that existing in the field of ore dressing. Under such conditions, a knowledge of the factors governing the selection Paid operation of primary-crushing equipment is essential to the economical production of a satisfactory material.

Jan 1, 1939

Bahrain's oil revenue increased from $337 million2 in 1916 to $378 million in 1977. Despite the increase in value, petroleum receipts made up only 584 of all Government income in 1877, compared with 74% in 1976 and 83% in 1975. Bahrain became an oil producer in 1932 with the discovery of the Awali oilfield, and since that time, the Awali oilfield has produced over 600 million barrels of crude oil. Awali production in 1977 was 21.2 million barrels. Bahrain shares the revenue from the Abu Safah oilfield, located in the Persian Gulf north of Bahrain, equally with Saudi Arabia. Revenue from the Abu Safah oilfield was approximately $179 million or 47% of oil revenues in 1977. Output from the Abu Safah oilfield was 48 million barrels, an increase of nearly 30% over 1976 output. The Bahrain Petroleum Company (BAPCO). the nation's only oil-producing company, was owned 40% by California Texas Oil Corp. (CALTEX and 60% by the Govern¬ment. The Government established Bahrain National Oil Co. (BANOCO) in 1976 to administer the Government's share of BAPCO, oversee exploration concessions, and manage domestic marketing of petroleum products. The Government announced its intention to acquire 100% control of crude oil and natural gas production. CALTEX was to retain complete control of the 250,000-barrel-per-day oil refinery near Sitrah.

Jan 1, 1981

By Robert L. Lagace

This final report documents the work done by Arthur D. Little, Inc. (ADL) on behalf of the U.S. Bureau of Mines, Pittsburgh Mining and Safety Research Center (PMSRC), on Contract H0122026 (which began in August of 1971). Under this contract ADL provided technical assistance to the Bureau on a task basis on virtually all aspects of the Bureau's programs related to present and planned emergency and operational communications and miner location systems for underground coal mines. The work consisted of independent investigations, analyses, experiments, breadboard and prototype hardware development, workshops and technology transfer seminars on mine communications, and on-going evaluations and guidance related to the Bureau's contracted programs on electromagnetic noise, mine communications systems, and trapped miner location. This final report documents the work in two volumes, Volume I, "Emergency and Operational Mine Commun¬ications," and Volume II, "Seismic Detection and Location of Isolated Miners." The Tables of Contents of both Volumes are included in each Volume.

Jan 1, 1974

By William J. Campbell

Expansion measurements of platinum, added as an internal standard, are used for thermal calibration of X-ray cameras and diffractometers. Accuracy of the temperatures derived by this technique depends on the precision of expansion measurements and the reliability of reference expansion data. Temperature measurements to ± 1° C. require ?d or ?a to be determined within ± 0.001 percent. Selected expansion data are concluded to be reliable to 2° C., 5° C., and 25° C., over the temperature ranges 0° C. to 700° C., 700° C. to 1,000° C., and 1,000° C. to 1,700° C., respectively. Tabular expansion values from 25° C. to 1,700° C. in 2° C. intervals were calculated from the following equation; Expansion, percent = [8.91 + 1.28 x 10-3(t-25) + 0.04 x 10-6(t-25) ] [t-25.104 ] These tabular values facilitate future corrections of published temperatures as more reliable expansion-temperature data become available.

Jan 1, 1962

By R. A. Kearns

Biennially the Bureau of Mines issues a list of equipment that has been accepted as approved or permissible during the two calendar years immediately preceding the date of publication of the listing. By so doing the mining industry is kept informed of the availability of the latest equipment for safe use underground. This list supplements Bulletin 543, Permissible Mine Equipment Approved to January 1, 1953; Information Circular 7722, Permissible Mine Equipment Approved During the Calendar Years 1953-54; Information Circular 7840, Permissible Mine Equipment Approved During the Calendar Years 1955-56; and Information Circular 7957, Permissible Mine Equipment Approved During 1957-58. This list includes equipment meeting those standards that have been revised since Information Circular 7957 was .issued. Schedule 16E,4 a revision of Schedule 160, was approved May 19, 1960.

Jan 1, 1961

By A. C. Fieldner

[The Sectional Committee on Classification of Coals, functioning under the sponsorship of the American Society for Testing Materials and the rules of the American Standards Association, in its 1934 report recommended to the American Society for Testing-Materials that Specifications for Classification of Coals by Rank be adopted as tentative. These specifications, slightly modified as recommended by the Sectional Committee, in its 1935 report,6 wore approved as tentative standards by the society in 1935. The specifications rover the classification of coals according; to their degree of metamorphism, or progressive alteration, in the natural eerie s from lignite to anthracite. The basic scheme of classification is according to fired carbon and calorific value (expressed in B.t.u.) calculated to the mineral-matter-free basis. The higher-rank coals are classified according to fixed carbon on the dry basis, and the lower-rank coals according to B.t.u. on the moist basis, that is, containing its natural bed moisture but free of visible surface moisture. Agglutinating and weathering indices arc used to differentiate between certain adjacent groups.]

Jan 1, 1935

By Richard A. Dick

Underground blasting in permanently frozen gravel was studied in a 7-by 12-ft drift by running a nonreplicated 2 X 2 X 2 factorial experiment on the effects of type of cut, delay, and explosive on the fragmentation subsystem. Comparisons were made between a V-cut round and a burn-cut round, millisecond delays and half-second delays, and 40 percent special gelatin and 60 percent high-density ammonia dynamite. The number of large blocks in the muck pile) loading time, shuttle car operating time lost because of cleanup needs, length of advance per round, and length of muck pile were recorded and statistically analyzed. None of the blast parameters had a significant effect on the length of advance or length of muck pile, although the half-second delays tended to give a shorter muck pile than millisecond delays. The burn cut required less secondary breakage, less loading and cleanup time, and gave better overall fragmentation than the V-cut. The ammonia dynamite shots required less secondary breakage and less loading time than those using special gelatin. The half-second delays gave better overall fragmentation and required less cleanup time, but the millisecond delays gave a better loading rate. None of the differences between delays and explosives were notably significant.

Jan 1, 1970