Search Documents

By W. F. Wheeler

IN the study of the coals of Illinois now being carried on by the State Geological Survey, an attempt is being made to determine the most satisfactory basis of comparison between different coals. The following discussion is based upon work done for the survey in the laboratories of the State University and under the general direction of Prof. S. W. Parr. " Pure coal " has been defined by Mr. A. Bement1 as ash- and moisture-free coal, and the use of this " pure coal " as a basis for comparing different bituminous coals has lately been much discussed among engineers in the middle West. By some the B.t.u. of the pure coal is being used to check calorimetric results, and to calculate the calorific value of different coal-samples from the same seam, for which purposes it is necessary to assume-first, that the composition and calorific value of pure coal from different parts of the same coal-seam are uniform, and, second, that these values remain constant after the coal is mined, both of which assumptions there are reasons to believe are inconsistent with the facts. Certain variables are included in pure coal, as ordinarily defined, and disregard of them may lead to serious error. In any event, where delicate shades of difference are involved, no sure interpretation of results can be made, unless these variables be eliminated. As a basis of comparison between coals, ash- and moisture-free coal is much to be preferred to " dry coal," and still more is it to be preferred to " moist coal," as ordinarily reported in analyses. There are, however, two constituents other than ash and moisture which are similar in effect to them, and which

Jan 1, 1908

By L. J. Cabri, J. M. D. Wilson, R Lastra

An image analysis program can search for gold minerals in polished sections by scanning about 100 x 100 back-scattered electron images at a magnification of x400, allowing gold grains as small as 1 micrometre in diameter to be detected. Typically, a c.15 h overnight search of a product smaller than 45 micrometres will scan c.1 500 000 particles, providing data that are not easily obtained through manual operation of an optical microscope. The program locates grains of the correct brightness, acquires gold X-rays from them by wavelength-dispersive spectrometry, filters the data to remove artefacts and record the images and stage locations for subsequent retrieval. At the end of the run, the program allows the operator to verify and identify the grains found. Industrial studies at Canmet have included determining the nature of gold in cyanidation tailings, checking the mineralogy and size of gold grains in samples from an Indonesian Cu-Au concentrator and locating and measuring gold liberation and grain sizes in an ore

Jun 21, 1905

By Karl R. Becker

A variety of commercial detonators (fuse type and electric instantaneous and delay types) were subjected to impact and thermal stimuli to determine initiation stimulus levels and the dominant parameters in resistance to initiation. In the impact trials the detonators were impacted along their length to find the most sensitive region; threshold initiation limits obtained for these regions ranged from 3.47 to 20.82 joules (2.6 to 15.4 ft-lb). The friction sensitivity of the explosive component was an important parameter in determining sensitivity; various construction features of nonexplosive components played a role as well. In the thermal sensitivity trials, the detonators were heated from ambient to 100° C at an average rate of about 1.0° C/min, and thereafter at 0.5° C/min until they exploded; the explosion temperatures observed ranged from 121° to 188° C. These temperatures correlated quite well with the reaction temperatures of certain characteristic explosive components used by different manufacturers. The data also indicated an effect of confinement on explosion temperatures of detonators.

Jan 1, 1975

By John Paul Gries

This Bureau of Mines report reviews the mineral industry of the Black Hills area, including Butte, Custer, Fall River, Lawrence, Meade, and Penning- ton Counties, S. Dak.; and Crook, Niobrara, and Weston Counties, Wyo. It includes discussion of geological occurrence, processing, and potential of 27 commodities that have been produced from the nine-county area. The value of mineral production exceeds $70 million annually. Gold and petroleum account for two-thirds of the total, followed by clays, cement, sand and gravel, and rock. The combined mineral industries annually consume 268 million kilowatts of electrical energy, 933 million Mcf of gas, and 2 million barrels of fuel oil. Water consumption is about 10,000 gallons per minute. About 2,700 persons are employed on a year-round or significant part-time basis.

Jan 1, 1974

By Paolo Cavalcoli, Marco Ziller

"ABSTRACT: In the year 2010 the State of Denmark together with the Municipality of Copenhagen, launched a very important and complex Project : the complete construction of a new double Subway Line :the CITYRINGEN.Copenhagen is the capital with a metropolitan population of 1,9 million.This line is like a ring placed in the very town center which includes all the most historical and monumental buildings and churches, with a total length of 17 km, and the presence of 17 stations plus 4 service shafts.The buildings have been built in the last centuries in an area where the groundwater is near to the surface and there are lakes and channels: the techniques adopted were advanced for those times, but limited as far as regards settlements and resistance to horizontal movements.The soil consists in 2 main groups.1.Upper sediments of the glacial ages : thickness total = 5-20 m composed by clay- silt-sand-gravelcobbles- granite boulders and flint in blocs and in layers : frequency and size of these obstacles wherenot determined.2.Limestone layers : 2a. upper limestone : highly fractured ,highly permeable2b.Itermediate limestone : less fractured, medium permeability.2c. Lower limestone : almost not fractured, low permeability.2d Bryozoan limestone : composed by fossils with microscopic dimensionsIn all the limestone formations there are important layers of flint , having thickness variable up to 3 m and important extensions. Water : in a part of the areas of the Cityringen the water is drinkable and utilized in the public waternet.Pollution: there are polluted zones due to previous industrial activities. Benzene areas have been identified, and for those areas special protections against pollution have been implemented.METROSELSKABET ,the public owner of the Cityringen,has set as priority to operate for the construction of the Cityringen the full protection of the environment and the respect of all the stakeholders :Very strong limits for the exhausted gas emissions have been introduced, by far stronger than those applied from the State of Denmark, very strong limits for the acceptable noise emission. And last but not least very important safety measures and procedure to avoid any accident on site."

Jan 1, 2014

By T. Shibasaki

Purification of copper electrolyte at Naoshima is carried out by two stage liberation to completely depress copper and impurity ions followed by concentration of the solution to produce crude nikel sulfate as by-product. A new nickel recovering process has been developed and pilot tested recently. It consists of the following process steps.; neutralization of spent electrolyte from liberation section to remove free acid and most part of remaining impurity ions, refining and nickel concentration by solvent extraction, and crystallization of pure nickel sulfate from concentrated strip solution. This paper describes the results of laboratory and pilot plant tests, then briefly discusses feasibility of the proposed process.

Jan 1, 1987

By E. H. Burroughs

This bulletin is the fourth in the series of petroleum bibliographies being published by the Bureau of Mines, the three preceding, Bulletins 149, 165, and 180, being compilations for the years 1915, 1916, and 1917, respectively. In this bulletin the same general plan has been followed in arranging the references, but a few changes and additions have been made in the classification, the more important changes being in the classes "Geology and Origin" and "Refining and Refineries." Dl1'ring the year German periodicals were not available, and, as in the bibliography for 1917, references to articles in foreign journals that were not available have been taken' from other sources and credit given to those sources.

Jan 1, 1921

Jan 1, 2003

By James Westfield

Following is a resume of activities of the Division of Coal-Mine Inspection that have had a favorable effect on health, safety, and the reduction o1 injuries at coal mines: 1. The Federal Mine Safety Code for Bituminous Coal and Lignite Mines of the United States was issued originally by the Director of the Bureau of Mines July 24, 1946, after consultation with management and labor representatives of the coal-mining industry. The code has been used by Federal coal-mine inspectors while inspecting bituminous coal and lignite mines as a basis for determining the existence of unhealthful and unsafe conditions and practices in these mines. A revised code was issued by the Secretary of the Interior October 8, 1953, after further consultations with representatives of management and mine workers and was incorporated by reference in the 1952 and subsequent bituminous coal wage agreements. The agreement of May 29, 1946, between the Secretary of the Interior, acting as Coal Mines Administrator under authority of Executive Order 9728, and the United Mine Workers of America, covering bitumi¬nous coal and lignite mines in Government possession, charged Federal coal-mine inspectors with the responsibility of making periodic investigations of the mines and reporting to the Coal Mines Administrator any violations of the Federal Mine Safety Code. Federal coal-mine inspectors also had temporary authority to close mines found to be imminently dangerous, but such authority (under Executive Order 9728) was removed June 30, 1947, when Government control of the mines was terminated.

Jan 1, 1959

By John R. Duda

The Bureau of Mines is developing estimates of capital investment, operating cost, and selling price for underground mines producing bituminous coal by various mining methods. This study estimates the required capital investment, operating costs, and selling prices for two hypothetical mines designed to produce 1.3 and 2.6 million tons per year (MM tpy)3 by using a longwall system in conjunction with a continuous-mining system. The coal properties being mined are assumed capable of sustaining a 20-year production period. Wages and union welfare payments used in this study are those in effect as of December 6, 1975, as set forth under the National Bituminous Coal Wage Agreement of 1974. Costs of materials and equipment are based on January 1976 indexes. Initial capital investment is $34.6 million for the 1.3-MM-tpy mine and $63.5 million for the 2.6-MM-tpy mine. Capital requirements, including deferred investments, were estimated to be $50.8 and $92.2 million, respectively. These figures translate into total capital investments of $38.51 and $34.91 per ton of annual production. Assuming a desired 15-percent discounted cash flow (DCF) rate of return, with Federal income taxes at 50 percent, the required selling prices would be $13.41 and $12.27 per ton for the 1.3- and 2.6 -MM- tpy mines.

Jan 1, 1976

By Albert L. Toenges

The Grundy coal field is in process of development, and this circular was written to describe the mining methods and practices in use in the mines now being worked in this field. In lieu of man-hour labor data for individual mines a consolidated sheet of mine costs, which includes expenses for labor, material, and power, is given for all mines. The costs are for a working day only, based on average daily production. Because the demand for coal is seasonal, the costs for idle days, which vary at each mine, have not been estimated. Approximate reserves of coal seams have been estimated from data and maps taken from Bulletin XVIII of the Virginia Geological Survey4/.

Jan 1, 1936

By Edward P. Barrett

SPONGE IRON has been defined as the metallic product formed by the reduction (removal of combined oxygen) of iron ore or other iron oxides at temperatures below the fusion point of iron. This product probably derived the name "sponge iron" from its porous nature. When the reduction proceeds at slightly higher temperatures and the particles of metal weld together or finally even melt to yield pellets or balls that lack the porosity and low-density characteristic of sponge iron, the product might more correctly be called "direct iron."

Jan 1, 1954

By D. J. Reddish

An understanding of the mechanisms that cause large seismic events in a deep mine provides a foundation for designing effective measures to reduce the incidence of these events, as well as reduce the potential for damage arising from these events. The work described in this paper focuses analytical efforts on major recognizable and controllable factors that influence mining-induced seismicity and serves to screen out many of the more random aspects of individual events. Information used in this study was developed in the course of a long-standing rock burst research program conducted by the U. S. Bureau of Mines in cooperation with mines in the Coeur d'Alene Mining District and regional universities. Information was collected on 39 seismic events having local magnitudes greater than 2.5 that occurred between 1989 and 1994. Five major types of events were developed from these data that describe all but two of the 39 large events. The characteristic mechanisms, tint-motion pattern, damage pattern, and relationships to mining and major geologic structures were defined for each type of event. This information provides a foundation for assessing whether or not changes in mining activity aimed at reducing one type of rock burst will increase the incidence of other types.

Jan 1, 1996

By L. H. Van Vlack, T. Y. Tien, R. J. Martin

The phase relationships of the MnTe-MnS system were studied by DTA procedures. There is an eutectic at 810°C with about 10 mole pct MnS-90 mole pct MnTe. An eutectoid occurs at about 710°C with approximately 7 mole pct MnS where the MnTe(NaCl) solid solution dissociates on cooling to MnTe(NiAs) and MnS. There is very little solid solubility of MnTe in MnS. ALTHOUGH MnS may exist in three different crystal forms,' only the NaC1-type phase is stable.2 Above 1040°C, MnTe also has the cubic NaC1-type structure. Below that temperature, MnTe changes to the NiAs-type structure.3 This phase transition is rapid for both heating and cooling. As a result the high-temperature crystal form of MnTe cannot be retained at room temperature. Because MnO, MnS, and MnSe are all stable with the NaC1-type structure, and MnTe has this structure at high temperatures,4 solid solution formation could be expected among these compounds. It is interesting to note, however, that a complete series of solid solutions exist only in the MnS-MnSe system,' and that the solid solution is quite limited in the MnO-MnS system.' The MnSe-MnTe system possesses a complete series of solid solutions at high temperatures with separation at lower temperatures.7 Although ion size may be critical in the miscibility of MnO-MnS, it is quite possible that the bond type plays a more important role with the miscibility of MnSe-MnTe. This would permit us to speculate that the miscibility gap would be extensive in the MnTe-MnS system. EXPERIMENTAL Preparation. The samples were prepared by mixing and compacting MnTe and MnS powders. The MnS was previously prepared through the sulfur reduction of Mnso4.8 The MnTe had been prepared by mixing and compacting double vacuum distilled metallic manganese and high-purity tellurium in stoichiometric ratio modified with 1 wt pct excess tellurium. The compacted powders were put in a graphite crucible which was sealed in an evacuated vycor tube. The free space in the vycor tube was made minimal to reduce the loss of tellurium. The sealed assembly was then heated slowly to about 500° C where the free manganese and tellurium reacted vigorously, melting the MnTe which formed. Only one phase, MnTe, was detected by X-ray powder patterns and metallographic techniques. Each compact of MnTe-MnS was placed in a graphite crucible and then sealed in an evacuated vycor tube. The samples were heated at 1250°C for 4 hr and furnace-cooled. Microscopic examination revealed no third phase beyond MnS and MnTe. A typical microstructure is presented in Fig. 1. Identification. X-ray powder patterns were obtained using 114.6 mm Debye-Scherrer camera and Fe-Ka radiation. Mixtures of cubic MnS and hexagonal MnTe were observed in all of the compositions prepared. No lattice parameter change was noticed among different compositions, indicating no solid solution could be retained at room temperatures between these two end-members. A lattice parameter of 5.244Å for MnS was obtained by the Nelson and Riley9 extrapolation method using the diffraction lines of (h2 + k2 + 12) equal 12, 16, 20, and 24. The values, a = 4.145Å and c = 6.708Å, for hexagonal MnTe were obtained from the (006) and (220) lines in the back-reflection region. These values agree well with the values reported by Taylor and Kag1e.10 Differential Thermal Analysis. A differential thermal analysis procedure was used to determine phase relationships since the high-temperature equilibrium conditions could not be retained for examination at room temperature, even when the sealed samples (~0.5 g) were quenched in water. The samples were sealed in an evacuated 4 mm vycor tube with a recess in the bottom to accept a thermocouple. An Al2O3 reference was similarly prepared and the two placed within a piece of insulating fire brick to dampen spurious temperature changes within the furnace. The furnace was controlled by a mechanically driven rheostat which increased the temperature at a rate of about 15°C per min. Known phase changes in the Pb-Sn system1' and the a-to-ß quartz inversion12 were used for calibration

Jan 1, 1969

By John Wilson

"The unconformity beneath 75 per cent or over 6000 km2 of the Athabasca Basin in Alberta lies within economically exploitable depths. The basement beneath this unconformity consists of an extension of the Wylie Lake Pluton, locally faulted and containing areas of mylonitic rocks. While the rocks of the Wylie Lake Pluton are not promising host rocks for uranium ore deposits, the areas of mylonites, graphitic rocks and possible remnants of granitegneiss would bear closer examination. One area of maficmylonites shows a weathering zone enriched in Si, Ca, Na, Pb, Ni, Ba, Co, Sr, Zn and U in addition to reported values of 0.08 oz/ton gold. This zone occurs beneath 800 m to 900 m of Athabasca Group sediments, but similar rock types are present beneath much thinner cover elsewhere. Detailed geophysical exploration is required over the area of thinner Athabasca Group rocks to define more precisely the areas of promising basement rock type.IntroductionThe Athabasca Basin in Alberta has considerable economic potential which has not yet been realized. The geological setting is closely analogous to parts of the basin in Saskatchewan which host major uranium deposits. Recent advances in geophysical techniques have led to deposits being located in Saskatchewan below 600 m of cover. This means that the unconformity between the Athabasca Group and the basement lies at exploitable depths over 6000 km2 or 75 per cent of the Alberta portion of the basin. Much of this area was only cursorily examined almost a decade ago. In addition, Alberta's new Metallic Mineral Regulations have clarified the regulatory situation in the area, and opened up much land for exploration. This article is based on Wilson's (1985a) study of the Athabasca Group and Wilson's (1986) work on the basement and alteration beneath the Athabasca Group in Alberta."

Jan 1, 1987

By Ronald P. Hollenbeck

This study reviews and discusses the fluorspar industry in the Eastern United States, with emphasis on factors controlling the industry such as production, consumption, uses, and transportation. The greatest potential for increased consumption of fluorspar in the immediate future was found to be in the manufacture of fluorine chemicals and steel. Important factors affecting the future domestic industry include imports and the maintenance of adequate domestic fluorspar reserves. Exploration, commercial deposits, mining and milling, reserves, and new developments in the industry are covered.

Jan 1, 1967

By William Cochran

Data on the cost and quantity available were developed for rutile (TiO2), which is potentially recoverable as a byproduct at sand-washing plants in the Southeastern States of Alabama, Georgia, North Carolina, and South Carolina. Baaed on 1969 production data, an estimated 4,300 tons of rutile could be recovered annually from plants that process more than 25,000 tons of sand per year. Rutile prices at which this resource would be available ranged upward from $262 per ton, compared with the current market value of $185 per ton.

Jan 1, 1972

By M. Heger

February 2, 1999 marks a milestone in earth-moving technology at the San Miguel Lignite Mine. It was on that date that The North American Coal Corporation (NAC) took delivery of three Leica Dozer 2000 GPS grade control systems for use on its bulldozers. The primary reason for the purchase of these grade control systems was to prove that GPS technology could safely and economically be utilized on heavy equipment to assist operators in defining grades. If these properties were successfully demonstrated, the ultimate vision of the project was to expand the system to a point were GPS would become the primary means of providing grade control information to the mine’s heavy equipment operators. Twenty nine months and more than $500,000 later this vision was realized when the final bulldozer operating at the San Miguel Lignite Mine was equipped with Dozer 2000. Presently North American Coal has a total of nine Dozer 2000 GPS grade control systems at San Miguel providing cut and fill information to operators 24 hours a day. These grade control systems have allowed the San Miguel operation to increase safety, reduce costs, improve operator attitude, and better ensure environmental compliance. This article discusses both the nature of these benefits and some of the issues that had to be dealt with along the way.

Jan 1, 2002

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 L. K. Weaver

Bureau of Mines investigated the progressive impact that petroleum (crude oil and condensate) operations in the Gulf of Mexico have had on onshore operations and the expected effect of increasing activities in this area on future petroleum supplies from domestic sources. The data analyzed include capital expenditures, number of wells drilled, success ratio for exploratory wells, daily production per completion, annual producing rates, and oil reserves. The report compares offshore and onshore data and ascertains trends in petroleum industry operations. Observed data and trends indicate that in the near future Gulf of Mexico development and production will continue to increase relative to total U.S. petroleum activity. By 1975 annual oil and condensate production from the Gulf of Mexico is expected to be in the range of 750 million bbl to 1,150 million bbl, and account for approximately 20 to 30 pct of the estimated total domestic production.

Jan 1, 1969