Search Documents

By Mike Muchard

Augered cast-in-place piles are one of the most cost effective deep foundation options available to designers but have been largely underutilized due to skepticism associated with quality assurance and hence capacity. When installed correctly, unit friction values can rival any other competing foundation system. To this end, many means have been implemented to increase confidence in the competence of the foundation. One such method is load testing via the Statnamic test method. This paper presents an overview of the Statnamic test method, advantages and disadvantages of its use, and several case studies where Statnamic testing of augered cast-in-place piles confirmed quality construction, brought about design changes, or proof tested problematic installations.

Jan 1, 2000

By Foster Fraas

One of the lithium minerals most widespread in the earth's surface is spodumene (Li2O-A1203-4Si02) a lithium aluminium silicate. For some time, deposits of this mineral were known to exist in the Black Rills of South Dakota, but it was only quite recently that Hess4/ pointed out the great magnitude of the low-grade e deposits it s in North Carolina. The theoretical lithia (Li20) content of spodumene is 8.04 percent. The only other minerals with such high lithia content are the phosphates, but these occur only in pockets and are not in extensive deposits5/. Actually, however, the lithia content in spodumene is never found to be this high, being nearly always below 7 percent for the pure mineral, and part of the lithia is apparently replaced by other alkalies.

Jan 1, 1937

By S. R. Zimmerley

As a result of the drilling program of the :Mining Division, Bureau of Mines, large amounts of manganese ores have been blocked out in the Drum Mountain District of Utah. The ores, as mined, would not be acceptable for the production of ferromanganese, and this investigation was made to determine their amenability to concentration by ore-dressing methods and the amount of

Jan 1, 1942

By S. R. Zimmerley

As a result of the drilling program of the Mining Division, Bureau of Mines, large amounts of manganese ores have been blocked out in the Drum Mountain District of Utah. The ores, as mined, would not be acceptable for the production of ferromanganese, and this investigation was made to determine their amenability to concentration by ore-dressing methods and the amount of

Jan 1, 1942

By P. P. Jenkins, T. G. Ball

Paper presented at the Drillex '90 conference held in London, 5 April 1990. Two drilling techniques are employed - guided longhole drilling and reverse circulation coring - for underground longhole exploration of the coal reserves and the fault structures that affect them. These are complementary to, or replacements for, surface boreholes, underground development drivages and seismic techniques. The developments of the drilling techniques and some case histories are presented in detail.

Jan 1, 1991

By Ronald F. Balazik

This Bureau of Mines study identifies and examines the costs of Federal, State, and local environmental protection controls on domestic phosphate rock mining, The costs include the expenditures needed to comply with government regulations and the effects that these expenditures and regulations have on supply. The study analyzes costs of environmental impact assessments, air and water quality standards, reclamation laws, potential solid waste controls, and local government restrictions. In addition, an industry survey and the Bureau's Minerals Availability System (MAS) are used to evaluate land management policies that restrict access to phosphate resources, Conclusions drawn from these analyses confirm that (1) domestic phosphate mining has incurred substantial control costs and may be subject to significant new regulatory costs in the next several years, (2) certain environmental controls can discourage mining investment, (3) environmental policies governing land-use controls affect the disposition of sizable phosphate resources, and are key determinants in the development of those resources on the Federal do- main, and (4) environmental costs could diminish the competitiveness of domestic producers.

Jan 1, 1983

By J. H. Holden

Operations involving the processing of coal, oxygen, and steam into synthesis gas by means of two pressure-type gasifiers have demonstrated the effect of heat loss and operating variables on carbon gasified and oxygen and coal requirements. Carbon gasified is the fraction of carbon in the coal that is converted to gas. Oxygen and coal requirement is the quantity of each that is needed to produce a unit volume (M std. c.f.) of carbon monoxide and hydrogen. Operating pressure of the gasifiers ranged from 150 to 300 p.s.i.g. and coal was fed at 200 to 500 lb./hr./cu.ft. of reaction-zone space. Oxygen-to-coal ratios were 8.5 to 10.5 std. c.f./lb. Heat loss and residence time have opposite effects on carbon gasified; increasing the heat loss decreases the carbon gasified, but increasing the residence time (by raising the operating pressure or reducing the coal-feed rate) increases the carbon gasified. The effects of these two factors are difficult to separate because they usually change simultaneously. A comparison of the results obtained from the operation of two gasifiers with different levels of heat loss, however, permitted the effect of heat loss to be separated from that of pressure and coal-feed rate. When the results were deter- mined on the basis of constant heat loss, increase of the residence time increased the carbon gasified until the reaction virtually had come to completion. For example, at 150 p.s.i.g., decreasing the coal-feed ratio from 500 lb./hr./cu.ft. to 200 lb./hr./cu.ft. substantially increased the carbon gasified. At 300 p.s.i.g., however, changing the coal-feed rate had little effect on the carbon gasified because the reaction had almost reached completion and further increase in residence time resulted only in a negligible change.

Jan 1, 1962

By Harry Perry

One of the most notable achievements of the iron and steel industry in the United States in this century has been the general increase in productivity of individual blast furnaces and the reduction in coke rate. Most of the improvement in furnace operations has occurred within the past decade. During this time the output of the average furnace increased about one-third, while fuel rates decreased from 15 to 20 percent. For example, in 1949, the iron and steel industry produced 811.2 short tons of pig iron per blast-furnace day with a coke rate of 1,870.4 pounds per ton of pig iron, By 1960, the average production of pig iron per blast-furnace day had risen to 1,182.4 tons, while the coke rate had decreased to 1,497 pounds per ton of pig iron. These figures are averages for the entire industry; many furnaces produced over 2,000 tons per day and one furnace, operating on pellets, reached 2,700 tons of pig iron per day, Coke rates of individual furnaces varied, but some furnaces operated on less than 1,200 pounds per ton of pig iron. The significance of this decrease in coke rate is shown clearly when data on pig-iron production and coke consumption in 1959 are compared with 1948. In 1948, 57.3 million short tons of coke was charged into blast furnaces to produce 60.1 million tons of pig iron; in 1959 only 47.6 million tons of coke was needed to produce 60.2 million tons of pig iron. Thus, in 1959, nearly 10 million tons less coke was required to produce about the same amount of pig iron as was produced in 1948.

Jan 1, 1962

Geophysical Abstracts 1 - 86 were issued in mimeographed form by the Bureau of Mines; Abstracts 87 - 111 were published in bulletins of the Geological Survey; Abstracts 112 - 116 were issued in mimeographed form by the Bureau of Mines as Information Circulars 7256, 7257, 7267, 7273 and 7285. 1. GRAVITATIONAL METHODS 7380. Dryden, H. L. A reexamination of the Potsdam Absolute Determination of Gravity. Jour. Research Nat. Bureau of Standards, vol. 29, No. 5, 1942, pp. 303-314.

Jan 1, 1944

By Clarence Karr

THE BUREAU OF MINES is investigating methods for upgrading tar produced by the low-temperature carbonization of bituminous coal. This survey was undertaken to compile information needed for identifying the ether constituents of low-temperature tar. Physical properties are listed for 1,024 aromatic ethers. The compounds include cyclic and noncyclic, polyfunctional and monofunctional ethers with oxygen joined directly to either one or two aromatic rings. Alkyl groups up through butyl are included. The compounds are divided into 37 groups ranging in complexity from alkoxybenzenes to dibenzopyrans. Compounds containing aromatic ether groups are important constituents of the neutral oxygen components of low-temperature tar. For example, at Morgantown, W. Va., the Bureau of Mines has identified and determined the amounts of benzofuran, 2-, 3-, 5-, 6-, and 7 -methylbenzofuran, diphenyl ether, dibenzofuran, 2,3-dimethyldibenzofuran, and two other dimethyl-dibenzofurans in the neutral oil from a low-temperature bituminous coal tar (103, 104).3

Jan 1, 1962

By James Westfield

Following is a brief resume of the Division's activities that have had a favorable effect on health, safety, and the reduction of 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 on July 24, 1946, after consulting 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 on 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 bituminous-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 on June 30, 1947, when Government control of the mines was terminated.

Jan 1, 1961

By Eldon C. Pattee

Reconnaisance samples of reported beryllium occurrences in Idaho, Washington, Montana, and Oregon were chemically and spectroscopically tested in a mobile laboratory. The two predominant types of occurrences were green beryl associated with Cretaceous intrusions and disseminated aquamarine associated with Tertiary intrusions. Although the beryllium content of known deposits in the Northwest is too low for economic development at present, total submarginal-grade beryllium resources in pegmatites are estimated to be 570,000 to 1,870,000 tons containing 0.024 to 0.167 BeO. A potential source of 500,000 to 700,000 tons of beryllium-bearing tactite in Idaho and Montana averages 0.033 to 0.080 percent BeO.

Jan 1, 1968

The deposit was discovered during systematic reconstruction of the geological history of glacial overburden, which averages 6 m in thickness over 80% of Sweden, by geochemical sampling and searching for small grains of eroded bedrock. The gold is mainly concentrated in and around high-grade quartz veins within a broad shear zone, though the correlation coefficient between quartz and gold in samples is not significant. Production from two pits, now connected, in the Central and Eastern orebodies has increased steadily from 1 238 kg Au in 1989 to 2 120 kg in 1994, the highest in Europe. The mine has adapted and improved its mining methods to achieve significant productivity increases and cost reductions. Most of the improvements have been achieved through a better understanding of the controls on mineralisation and of the implications of those controls for selective mining. Geostatistics has played an important role in the quantification of grade variability and gold occurrence. Better blasting and loading techniques have improved selectivity, grade control has been enhanced by a grade-control drilling programme, and significant improvements in mineral processing have been made

Dec 1, 1995

By Robert C. Steckley

A study of joints in Marathon County, Wis., was made to determine the orientation of regional paleotectonic stresses and to develop a method of using optical diffraction analysis (ODA) in studying joint orientations and spacings. Standard geologic and petrofabric techniques employing the use of a geologic compass and a Schmidt net were used in gathering, describing, and reducing joint orientation data. Analysis of selected outcrops with ODA indicates that ODA can be applied to study both joint orientations and spacings. ODA is shown to be a rapid method that can be used to complement standard petrofabric techniques, especially in the study of joint spacings.

Jan 1, 1972

By Paul C. McWilliams

The U.S. Bureau of Mines has, primarily through its contract program, used large-scale centrifuges to determine design criteria for tailing embankments. The centrifuge runs were made at two installations, the University of Cambridge, Cambridge, England and Sandia National Laboratories, Albuquerque, NM. The major problems considered were as follows: slope stability of embankments, modeling erosion and seepage, use of the phreatic surface level to ascertain the validity of centrifuge modeling, and the effects of compaction and weathering on a tailings embankment. This report summarizes the results of the four test series conducted at University of Cambridge and Sandia National Laboratories. A review of prior centrifuge applications to mining problems is included. Consideration is given to future centrifuge application to mining problems in both soil and rock mechanics.

Jan 1, 1989

By R Lastra, J. A. Finch

An artificial standard material has been developed and used to examine the robustness of some of the procedures for correcting stereological bias. Different mineral liberation distributions were constructed from the standard material. The particles were mounted, sectioned and the sectioning data measured with an electron microscope interfaced to an image analyser. Four correction procedures were used and the corrected and true liberation distributions compared. It was found that the large-sections correction provided a simple, uncorrupted correction. Hill's fast approximation performed well except in cases of narrow liberation distributions; the sectioning data appeared to support the assumption that the locked section and locked particle distributions are identical. Barbery's correction performed well in most cases, having difficulty only with the very irregular liberation distribution. The PARGEN correction was able to provide a good estimate of the true amount of free material, but had difficulty in predicting the locked particle distribution

Jun 21, 1905

By B. G. Tarasov

This paper proposes the further development of a recently identified shear rupture mechanism (fan mechanism) that elucidates a paradoxical feature of hard rocks ? the possibility of shear rupture propagation through a highly confined intact rock mass at shear stresses that can be significantly less than frictional strength. In the fan mechanism, failure is associated with consecutive creation of small slabs (known as ?domino blocks?) from the intact rock in the rupture tip, driven by a fan-shaped domino structure representing the rupture head. The fan head combines such unique features as extremely low shear resistance, self-sustaining stress intensification, and self-unbalancing conditions. Consequently, the failure process caused by the mechanism is inevitably spontaneous and violent. Physical and mathematical models explain unique and paradoxical features of the mechanism, which can be generated in primary ruptures and segmented faults. The fan mechanism provides a novel point of view for understanding the nature of spontaneous failure processes, including shear rupture rockbursts. The process explains, in particular, features of shear rupture rockbursts such as activation at great depths, generation of new shear ruptures in intact rock mass, nucleation of hypocentres at significant distances from the excavation, shear rupture development at low shear stresses, and abnormal rupture violence.

Jan 1, 2014

By Charles W. Axten

Since the mid-1970s, samples of airborne and waterborne fibrous particulates have been collected in the area of the Northshore Taconite Ore Processing Facility by the Minnesota Department of Health (MDH), the Minnesota Pollution Control Agency (PCA), and the University of Minnesota. Indirect sample preparation has consistently been used although other aspects of the sampling methods and sites have varied and analytical procedures were altered over time as more accurate and precise microscopy methods were developed (i.e., phase contrast optical microscopy, transmission electron microscopy, transmission electron microscopy with energy dispersive spectroscopy). In the mid-1970s, levels of airborne fibrous particulate in the Silver Bay area averaged from 0.00030 to 0.03 f/ml. This level was significantly greater than levels of similar particulates in the St. Paul, MN area, although two of the Silver Bay sampling sites, considered individually, did not indicate levels of fibrous particulate markedly different than that seen in St. Paul. More recent sampling data (i.e., 1990?2001) indicate mean concentration of airborne fibrous particulates (amphibole-like fibrous particulates) of 0.0020 f/ml with a range of values from 0.0001 to 0.0140 f/ml. Such levels are not significantly different from those seen in other non-urban environments in the US and Europe. Concentrations of fibrous particulates in water samples were higher in the mid-1970 when iron ore tailings were being deposited in Lake Superior, but since the tailings have been deposited on land waterborne levels of fibrous particulate in the Beaver River have remained relatively constant averaging in the range of 7.5 MFL. This level is only slightly in excess of the current EPA drinking water standard for fibrous particulates. Review and consideration of this data is important in determining the potential health risks associated with airborne and waterborne fibrous particulates in the areas of the Northshore Taconite Ore Processing Facility. © 2007 Elsevier Inc. All rights reserved. Keywords: Taconite; Asbestos; Asbestiform fibers; Fibrous particulates; Cleavage fragments; Phase contrast optical microscopy; Transmission electron microscopy

Jan 1, 2007

Very few of those occupied in pursuits other than mining have any conception of the extent of boring operations that have been carried out on the gold and coal fields of Victoria, or of the valuable and definite knowledge obtainable by such means. The subject comprises various branches, which it will be necessary to describe in detail. The three main divisions are The Administrative, which includes all financial work and general management. The Professional, dealing with topographical and geological work necessary before any scheme of boring can be laid out, the preparation of plans, the inspection of cores obtained from bore holes, the examination of diamonds, etc. The Mechanical Branch, dealing with the drilling machinery, setting of diamonds, maintenance of stores, etc. In 1877, the Goverpment of Victoria decided to assist in prospecting the mineral resources of the colony by the aid of diamond drill boring, and for that purpose, a vote of £5,000 was passed, with which were purchased three diamond dulls, an American type being adopted.

Jan 1, 1901

By Joseph A. DeCarlo

Coal is one of our basic sources of energy (heat, power, light) and an essential raw material for most metallurgical processing. More than two-thirds of the electricity currently produced by thermal powerplants in the United States is generated by coal, and it is expected that coal will continue to be the major fuel used for this application at least through the 1970's. Coke produced from bituminous coking coal is the principal fuel of iron blast furnaces, and unless ironmaking methods change greatly, coal will continue to maintain a dominant role in iron-ore processing and steel manufacturing for many years. Export markets are expected to increase also, adding to the overall increased demand for coal. Accompanying the increased total requirement, however, will be an ever-increasing demand for higher quality coals, specifically, coals of low sulfur content. Except for special-purpose coals such as those used for the production if coke and ceramics where impurities in the fuel contaminate the end product, the amount of sulfur in coal has been only a minor consideration in the selection of a particular coal for fuel. Major considerations, particularly for the coals used to generate electric power, have been availability and cost. An increased national concern for control of air pollution, however, particularly that resulting from the emission of sulfur oxides in stack gases to the atmosphere, has led to more rigid specifications on coal quality, and the sulfur content of coals will become increasingly more important in the future.

Jan 1, 1966