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By H. E. Dresch

This report summarizes the work accomplished under Bureau of Mines contract H0188068. The contract required design and construction of a high voltage (7.5 KV) explosion proof cable connector for use on underground coal mine drag cables. A connector was constructed with elastomeric phase insulators that provide insulation shielding throughout the connector length. Connector housing was made of flame resist-ant cast poly urethane with no exposed metal components. Electrical and mechanical testing of the completed coupler resulted in satisfactorily meeting most of the design testing requirements.

Jan 1, 1981

By Carlton E. Brown

In 1935 , Brown and Yant / described a microprojector ( microscopic arrangement for projecting images on a screen ) for use in counting and measuring the size of dust particles in Owens - jet dust - counter and simila dry samples of dust collected from the air . In 1938 Brown and others , described a modification of this microprojector that could be used also in counting dust in impinger samples . Microprojectors of this second type have been set up by many mining companies and others and have been made commercially available . Hamly and Pullen5/ described a modification of this microprojector for use in making rapid comparative estimates on konimeter samples and other determinations . This report contains information on still another modification named the "midget microprojector " because of its small size .

Sep 1, 1944

By R. J. Fantel

The Bureau of Mines investigated the resource potential of 201 mines and deposits in 28 market economy countries and 17 mines and deposits in the U.S.S.R. and China. The 201 mines and deposits evaluated from market economy countries contain an estimated 34.2 billion metric tons of recoverable phosphate rock (at the demonstrated resource level), with Morocco and Western Sahara accounting for 61% (21 billion tons), followed by the United States with 19% (6.4 billion tons). The 17 mines and deposits evaluated in the U.S.S.R. and China contain approximately 1.5 billion tons of potentially recoverable phosphate rock. Potential annual capacity from low-cost, high-grade producing mines in the United States is estimated to decline significantly during the latter half of the next decade, and the United States will have to develop new, higher cost, lower grade mines in order to satisfy demand into the next century. Of the world's new production capacity which could likely be developed over the next decade, slightly over one-third could be produced at an estimated 1981 cost of $40 per ton or less, and about two-thirds would cost in the $40 to $50 range (including a 15% rate of return). In comparison, moot of the competing phosphate rock from producing mines in Morocco could be produced for under $40 per ton. The United States has sufficient demonstrated resources of phosphate rock (plus huge quantities at the identified and hypothetical resource levels) to satisfy domestic consumption for many years to come, but its future ability to compete in the major export markets against low-cost competitors is much more uncertain.

Jan 1, 1984

By L. W. Scott

This report presents an overview of explosionproof (X-P) enclosure research being conducted by the Bureau of Mines, This report emphasizes the increasing importance of research related to the safety con- siderations of X-P enclosures used in underground coal mines. Selected topics are included that summarize results of research in the areas of electrical clearances, reliability of enclosures with windows, safety factors in X-P enclosures, potting materials, performance tests for X-P enclosures, protection against high-voltage explosions, and innovative X-P devices.

Jan 1, 1985

By H. D. Bemis

This paper describing the milling practice of the American Metal Co. at its Pecos con¬centrator is one of a series on milling methods and costs being prepared by the United States Bureau of Mines. ACKNOWLEDGMENT The author acknowledges the assistance rendered by Guy Martin, metallurgist, H. E. Brown and J. H. Hastings, chemists, and Thomas J. Fahey, accountant, in gathering and pre¬paring the data presented in this paper.

Jan 1, 1932

By Jon C. Volkwein

The U.S. Bureau of Mines investigated a method of using inert gas to prevent the formation of explosive gas mixtures in auger highwall mining of coal. A combination of gasoline and diesel engine exhaust gases was introduced into the auger drill hole using a short section of pipe located at the collar. Gas samples were taken and analyzed on-site with infrared detectors for oxygen, carbon dioxide, methane, and carbon monoxide. Evacuated bottle samples were also taken and analyzed by gas chromatography in the laboratory. These gas results were analyzed for explosibility. Coal samples from various depths were used to obtain the gas content of the coal using the modified direct method. Personal expo- sure to carbon monoxide was also monitored. The highest methane level observed was 9.55%. The levels of inert gas (carbon dioxide and nitrogen) were sufficiently high to prevent any ignition of the methane. Results showed that for all conditions during mining, gas concentrations were nonexplosive. The gas content of the coal was about 0.30 cm3/g. The maximum personal time-weighted average Sample for carbon monoxide was 20 ppm. This system provides a safe, inexpensive, simple method for preventing explosions during auger mining.

Jan 1, 2010

By Robert E. Wood

The compressibility factors, Z, of helium, nitrogen, and helium-nitrogen mixtures in the three-dimensional space of temperature, pressure, and gas composition have been related to the Leiden form of the virial equation of state. The dependency of virial coefficients through the fifth on temperature and gas composition has been established for the temperature range 133.15° to 748.15° K. Compressibility factors, Z, have been computed from the equation of state and tabulated as functions of gas composition, pressure, and temperature. Tabular values of Z are presented for 30.00 through 100.00 percent helium for temperatures from 240° through 700° R for pressures from 14.696 through 3,050 psia and for temperatures from 720° through 1,300° R for pressures from 14.696 through 1,500 psia. Tabular values of Z are presented at increments of 5.00 percent helium and 20° R, and, for pressures greater than 50 psia, at increments of 50 psi.

Jan 1, 1967

This publication summarizes the research (in-house and contract projects) programmed by the Bureau of Mines for fiscal year 1985 (October 1, 1984-September 30, 1985) under its Health and Safety Technology Program. The objective of these projects is to provide an ordered and sequenced advance toward the Bureau's overall goal of providing the system technology required to create a more healthful and safer working environment for the Nation?s mining and minerals processing workers.

Jan 1, 1985

By G. S. Rice, H. P. Greenwald, H. C. Howarth

"""Rock-dust barriers""5 as they are termed in this country, are for the purpose of confining a coal-dust mine explosion to the limited area in which it originates. These barriers were first tested in 1910-1911, with favorable results under the conditions of test, at the French official gallery which was then at Lieven, Department of Pas-de-Calais. Shortly afterwards the Bureau of Mines in the course of its investigation of all practical explosion-prevention methods tried barriers in the Experimental Mine near Bruceton, using the primary form of simple fixed cross shelves 20 inches wide extending over the passageway and laden with rock-dust. The Bureau termed them “Taffanel barriers"" in honor of the director of the Lieven testing station. The trials were made in conjunction with tests of explosibility of different coal-dusts.Experience showed that although the principle of barriers had merit when they were used for secondary defence, the primary form was uncertain in effectiveness. This led the senior author to design mechanically discharging barriers to be operated by the compression air waves which precede the flame of an explosion. For the better understanding of the principal involved, it is pointed out that the advance air waves are what make a coal-dust explosion possible by stirring up the coal-dust from the walls and floor of the passageway. If a barrier can throw inert dust into the air to form a cloud as dense or denser than that formed by the coal-dust, it will neutralize the explosiveness of the coal-dust, and the flame of the explosion will be extinguished. When the flame ceases, the pressure dies away in a short distance if the 'area that had been traversed by the explosion is not large."

Jan 1, 1930

By Arthur E. Wells

"The present and possible future commercial production of potash from various sources in the United Status is discussed below under the following heads:1. Potash from the saline lakes.(a) Nebraska lakes.(b) California lakes.(c) Other lakes.2. Potash as by-product from the cement kilns.3. Potash as by-product from the iron blast furnace.4. Potash from silicate rocks.(a) Feldspathic material.(b) Leucite rocks of Wyoming..(c) Sericite slates of Georgia.(d) Glauconite (greensand) of New Jersey.5. Potash from Alunite.6. Potash from organic sources other than kelp.7. Potash from kelp.In this discussion very little more than passing reference, if any, will be given to those projects which up to date have been developed only slightly, if at all, beyond the small scale laboratory stage, or for the development of which there appears to be very little financial and technical backing at the present time. Nether or not many of these proposed projects have merit can be determined only by an actual operating demonstration.Generally speaking, the potash industry of the United States has been hardly more than marking time since the armistice. This is, largely due to the fact that the consumers of potash have been expecting that heavy shipments of foreign potash to the United States would be resumed soon at somewhere near the pre-war prices, and they have not seen owing domestic potash at present prices for many months. The result has been that domestic producers have been unable to sell their product at even cost and many producers of potash have been obliged to close down. Thu Nebraska lake plants were closed down in February. The California saline plants were operating at below capacity, and the only large alunite plant is closed down. Even the cement plants have little or no inducements to recover the potash being lost in their waste gases and the production is very small at present.This condition will doubtless continue until a definite policy is decided upon as to the future importation of potash salts from Germany and. France. If unrestricted importation is allowed at prices even 50% greater than in 1913, only a very few, if any, of the domestic projects will be in position to compete with the foreign potash immediately, and the present industry will probably greatly decline with little or no prospect for a future resumption of the industry."

Aug 1, 1919

By F. E. Armstrong

This Bureau of Mines publication reviews 237 papery on radiometric prospecting, which is the measurement of naturally occurring radioactivity in the earth's surface and its application to petroleum and natural gas exploration. Many theories and documented surveys are listed in both support and refutation of this reported phenomenon, and the Bureau of Mines is conducting research to obtain direct field information in order to determine the statistical credibility of a radiometric method of predicting petroleum accumulation.

Jan 1, 1973

By Robert G. Bottge

The Bureau of Mines has engaged m a program to determine the availability of land for mineral exploration and development in Alaska. Land availability, based on ownership and Federal and State laws and policies, is compared with mineral terranes and mineral deposits. This is the fifth of six regional studies, which cover the State with a comprehensive set of maps and data compilations. This study covers an area of 112.3 million acres in western Alaska. In July 1986, 41.0 million acres, 37% of the study area, were available for mineral exploration and development; 14.6 million acres, 13%, were available with restrictions; and 56.7 million acres, 50%, were unavailable. Nearly 65% of the unavailable land is classified as national parks, preserves, wildlife refuges, and wild and scenic rivers. Of the 34.0 million acres of mineral terranes that underlie the study area, 12.9 million acres, 38%, are available for exploration and development; 3.6 million acres, 11%, are available with restrictions; and 17.5 million acres, 51%, are unavailable.

Jan 1, 1988

By Robert L. Lappi

This report covers the final phase of a project demonstrating the economic efficiency of cross-ridge mountaintop coal mining. A demonstration mine was established at Big Wheel Gap in northeastern Tennessee. Not only was cross-ridge mining feasible for the selected site, but parallel cut methods could not be used due to a deficit in available spoil storage. Cross-ridge mining permitted coal extraction at a cost almost identical with costs simulated by computer projections using mathematical optimization techniques. No unexpected environmental problems were encountered. Volume I is accompanied by Volume II which describes the MATHMINE Mine Simulation System, software used to support the mining demonstration.

Jan 1, 1984

By G. R. Fitterer

In the manufacture of steel by any process the refining period involves the partial elimination of the metalloids carbon, manganese, phosphorus, and silicon, by virtue of their reactions with ferrous oxide. At the end of this refining stage the metal consists chiefly of iron in which small amounts of these materials are dissolved. Unless some deoxidizer is added to the steel at this time, the reaction between carbon and ferrous oxide will continue with such force that it is impossible to form sound steel in the ingot molds. Instead, the product will exhibit a marked porosity due to the formation and trapping of carbon monoxide-the product of the reaction mentioned. However, if deoxidizers are added, steel may be obtained which is dense and free from gas bubbles. At the same time the deoxidation products will remain in the steel as impurities. For example, silicon additions form SiO2 or combinations of SiO2 and FeO. Additions of manganese form deoxidation products consisting of various proportions of MnO and FeO. It is also quite obvious that simultaneous additions of manganese and silicon will form oxide combinations either in the binary system MnO-SiO2 or in the ternary system FeO-MnO-SiO2. Work at the Pittsburgh Experiment Station of the United States Bureau of Mines, in cooperation with the Carnegie Institute of Technology and the Metallurgical Advisory Board, involved the study of such deoxidizing reactions and their products. In this connection considerable information is necessary concerning FeO, MnO, SiO2, and Al2O3, and their various combinations. Some of the most needed data are the melting points of all of these materials. At the outset of this work ordinary methods of melting point determinations were found to be inadequate for various reasons, and the procedure finally selected involved the use of the micropyrometer with occasional corroboration by quenching methods. The reasons for this selection, together with a description of the apparatus, are given in the following pages.

Jan 1, 1932

By Albert L. Toenges

ALMOST all of the coal used for metallurgical purposes west of the Continental Divide is ruined from the Lower Sunnyside bed in Carbon County, Utah. Coke produced from Lower Sunnyside coal and used in western steel plants is weaker structurally than coke used elsewhere in this country. For this reason, western coal operators and steel manufacturers are anxious to develop new areas of coking coal of better quality than the coal produced from the Sunnyside bed. Early in the war, the Bureau of Mines undertook an intensive investigation of western coals to (a) develop additional reserves of coking coal to supplement proved reserves in the Sunnyside bed and (b) develop, if possible, reserves of coal with coking qualities superior to Lower Sunnyside coal. Results of investigations in the Kemmerer district, Wyoming,9 and in the Minnesota Creek area, Gunnison County, Colo.,10 have been published.

Jan 1, 1952

By B. H. Clemmons, C. H. Schack

Extractive metallurgy techniques currently employed to recover silver from primary ores and secondary scrap were reviewed and evaluated to identify and delineate metallurgical problems whose resolution would increase the supply of silver from domestic materials. The survey revealed that practically all primary silver is recovered by froth flotation concentration of various types of ores, followed by smelting and refining of the separate lead, copper, and zinc concentrates. Silver losses during the complex processing are, with rare exception, inconsequential. Furthermore, any silver production gain from base metal ores, which contribute about two-thirds of the total primary silver, is directly dependent on improvement in the market for the base metals. Statistical data on new and old silver scrap are wholly inadequate to make reliable conclusions about scrap processing problems and the possibility of increasing the recovery of silver from the many forms of secondary silverbearing materials. The available information indicates (1) that efficient silver reclamation practices are employed by the larger users of silver, and (2) that recovery of additional secondary silver involves solution of problems of collection rather than of processing. Several possibilities exist for limited increases in silver production from primary ores by improvement in metallurgical practices. Specifically, research is needed to (1) solve the problem of recovering silver from the copper ores of the Copper Range district, Michigan; and (2) devise economically feasible methods for recovery of silver from presently marginal or submarginal ores that because of grade, location, and frequently complex nature cannot presently be exploited by conventional techniques.

Mar 1, 1965

By Jr. Harty

Intensive work on the deoxidation of steel with manganese-silicon alloys by the U. S. Bureau of Mines has shown that the use of those alloys, which may be produced from our domestic manganese ores, would decrease the ferromanganese requirements of a very large tonnage of our steel by from 60 to 80 per cent and in some cases by 100 per cent. The open-hearth heats made with these alloys have been of excellent quality. The tonnage of our ferro-grade ores Which has been made available by the bureau's ore-dressing studies, combined with the products resulting from such processes as those developed by the bureau and by Bradley for Cuyuna ores, should easily fill our reduced ferromanganese requirements when manganese-silicon alloys and ordinary Spiegel are used in the way described in this report. There are no technical difficulties in the application of this practice, and any difficulties involved in its wide and immediate application would only be those arising from habituated ideas of the necessity of ferromanganese. General acceptance of this practice and development of the available sources of domestic ferro-grade material by already proven processes should make this country independent of foreign ores. This paper resents the results of work done under a cooperative agreement between the Pittsburgh Experiment Station of the United States Bureau of Mines and the Carnegie Institute of Technology, the Metallurgical Advisory Board, and the University of Pittsburgh, Pittsburgh, Pa.; between the Mississippi Valley Experiment Station of the United States Bureau of Mines and the Missouri School of Mines and Metallurgy, Rolla, Mo.; between the North Central Experiment Station of the United States Bureau of Mines and the University of Minnesota, Minneapolis, Minn.; and between the Rare and Precious Metals Experiment Station of the United States Bureau of Mines and the University of Nevada, Reno, Nev.

Jan 1, 1931

By S. S. M. Chan

The Bureau of Mines has investigated the structural aspects of shafts and support systems using the finite-element technique. In situ field measurements in deep, vein-type metal mines show that rock stresses are often higher in the horizontal direction than the vertical, and unequal in the horizontal plane. These data and laboratory and field-determined physical properties were used as input to analytical studies. Various design and construction parameters were investigated to deter-mine the effect on shaft stability. Rectangular shafts were studied in detail to determine the effects of applied stress ratio, shaft orientation and dimension, influence of interbedded quartzite and argillite, and rock fracturing. Various support systems were analyzed, including concrete lining, timber, and steel sets. Circular configurations were investigated to evaluate yield zones and liner thickness. Elliptical shafts and time effects were briefly evaluated to illustrate shape and time effects and demonstrate the methodology. It is shown that the magnitude, direction, and ratio of applied stress and rock mass anisotropy are keys to determining shaft stability. A realistic conceptual framework was developed with which to examine the rock and support interaction in deep mine shafts. Structural analysis techniques overcome some of the historical difficulties with shaft de-sign by defining the field data requirements and structural sensitivity of various design and construction parameters.

Jan 1, 1985

By David J. Kusler

This report describes a rapid, reliable, and relatively simple method developed by the Bureau of Mines Pyrometallurgy Laboratory at Bruceton, Pa., for determining lime (calcium oxide) and magnesia (magnesium oxide) in various materials containing these constituents in greater than trace amounts. Optionally, titania (titanium dioxide) may be determined for the same sample. The accuracy of the method, suitable for most purposes, is shown by comparing the Bureau results with those obtained by accepted procedures. The method has been applied satisfactorily to the routine analysis of blast-furnace slags, for which purpose it was primarily developed, and to other calcareous compositions. In the Pyrometallurgy Laboratory it has replaced the standard methods previously used to determine lime and magnesia, and has been in general use by that laboratory for the past several years. The analysis time, generally under 3 hours, is considerably less than required by standard methods.

Jan 1, 1960

By C. T. Baroch

As part of a general program for investigating all phases of titanium production, argon was substituted for helium in the reduction step at the Bureau of Mines pilot plant, which employed a modification of the Kroll, or magnesium-reduction, process. Argon was substituted for helium in 108 of the 140 batches of sponge made during 1 month's reduction operations for July 1954. Argon was substituted for helium satisfactorily, with only slight modifications in technique. Metal quality, feed rate of TiC14, magnesium efficiency, and average production per batch were closely comparable with either gas. Argon runs were slightly more troublesome because of the formation of condensable chloride complexes, which tended to plug feed and vent lines and to entrap deposits of lower titanium chlorides on the reactor-pot lids. These lower chlorides were objection-able because they were pyrophoric and created obnoxious fumes when pots were opened. When feed and vent lines became plugged care was required in poking or unplugging these lines to prevent air from entering the reactor. These problems were relatively minor, and continued development of reactors and techniques for the use of argon should further minimize objectionable side reactions obtained when argon is used.

Jan 1, 1956