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By A. George Stern

In the examination of bentonitic clay suspensions used for oil-well drilling fluids3/ (and for other purposes, such as a core binder for foundry sand) it is important to have comparative tests for evaluating them. A satisfactory clay for these and other purposes should 'rave the property of forming what is commonly called a "gel," but the measurement of this property has been a real problem. To date the solution has not been satisfactory, and some of the difficulties are considered in, this, paper, which describes a simple form of instrument (identified as an eykometer) for measuring the yield point under hydrostatic conditions of non-Newtonian clay suspensions, including those muds that are thixotropic. An oil-well drilling mud serves several functions, many of which depend on the "gel" characteristics of the mud. Among the more important functions are: (a) To plaster the sides of the hole to prevent caving of the walls; (b) to prevent the loss of the circulating fluid out of the hole by seepage; (c) to carry sand and cuttings out of the hole to the surface as they are formed by the rotary drill; and (d) when circulation of the fluid stops for shut-down or other unavoidable cause, to hold the cuttings in suspension by the setting up of the gel, thereby avoiding the difficulties that result when these cuttings are allowed to fall through the fluid and pack at the bottom of the hole.

Jan 1, 1940

By Lynn Alcorn, Jeffrey Shawn Peterson

Data collected by the Mine Safety and Health Administration (MSHA) has shown that roof bolting machine (RBM) operators are the second most likely type of underground mining machine operator to be are over exposed to noise, per the MSHA Permissible Exposure Limit. In response to this, the Pittsburgh Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) has initiated a project to develop engineering noise controls for roof bolting machines. Key to this research is an evaluation of the duty cycle of a typical roof bolting machine operation and this paper presents the results of such an exercise for data collected at two cooperating coalmines. The evaluation entails a time motion study of an operators' shift, logging each activity for time (e.g., tramming the machine, drilling holes, installing the roof bolt, etc.) and the noise levels associated with each task with a Larson Davis Spark 705+ dosimeter. NIOSH post processed the data to determine which tasks the operator devotes the most time to and the noise dosage accumulated during those tasks. These results provide insight into which portion of the operators' duty cycle is the most prominent contributor to noise exposure and thus, where research activities for the development of engineering noise controls should be focused. It was determined that the task of drilling holes is the most significant source of the operators' noise exposure and project research has focused on engineering noise controls to reduce the noise emissions generated during the drilling portion of the machine duty cycle.

By T. N. Rushton

Rate minima are encountered in the reduction of magnetite with hydrogen. In a certain temperature zone, the reaction rate decreases with rise in temperature. This is inexplicable by classical kinetic theories; neither is a transition in reduction mechanism suitable for interpreting the observed behavior, This anomaly can be fully explained by hypothesizing two species of chemisorbed hydrogen with different adsorption coefficients and activation energies for adsorption. Competition between two energetic states of adsorption occurs with temperature rise, with the low energy state predominating below the anomalous temperature zone and the high energy state above it. The presence of two possible adsorption sites appears to be characteristic for oxidic adsorbents.

Jan 1, 1968

By Donald James Butler

Problems resulting from underground mines in three inactive mining districts in Colorado were investigated. The purpose was to determine how these problems could be reduced or eliminated in new closings -- essentially by benefitting from lessons of the past. Mines in Leadville, Westcliffe and the Cripple Creek-Victor districts were evaluated. Two basic types of problems were found to exist in the districts: environmental degradation and hazardous conditions. Environmental problems result largely from acid and toxic drainage from the runes and from leaching of surface waste rock piles and mill tailings impoundment. The acid drainage contributes high levels of metals to streams and deposits sediment in the stream bottoms. Erosion of waste piles is a lesser problem. Hazardous conditions from open or improperly sealed mine shafts and adits, mine subsidence pits, and from deteriorating and unsafe surface structures are common to the three districts. These problems become worse with the ravages of time and vandalism. Engineering solutions which would correct or reduce many of these problems are presented. These recommendations should also be applied to new mine closures, however, more basic changes are needed to effectively implement improved mine closures. The changes must take place in the areas of legislation, mining practices and education. Legislated regulations should realistically reflect the needs of both the mine operators, protection of the environment and the best interest of the general public. Benefits should be provided for compliance with regulations instead of penalties being assessed for noncompliance. Hazardous conditions and environmental problems associated with mines can be alleviated through improved mine design and effective cloning procedures. Education should provide an appreciation by the general public of past and present problems facing mine operators. This will result in an improved mining climate which, in turn, will insure a continuing supply of minerals to meet increasing needs.

Jan 1, 1983

By R. H. Thompson

Preliminary safe distances for blasting wiring from typical electromagnetic sources are presented. The distances are for underground coal mines and electromagnetic sources in the frequency range below 10 MHz. The distances are based on measurements performed at 3 locations in each of 3 coal mines. The measurement apparatus, measurement procedure, measurement results and the rationale used in the calculation of the safe distances are all described. The safe distances presented are dependent on the measurement results and their interpretation. More measurements are clearly necessary to establish the validity of the suggested distances.

Jan 1, 1985

By Donald O. Capstick

A mineral survey of the approximately 144,000-acre Borah Peak study area was conducted by the U.S. Bureau of Mines in 1985 at the request of the U.S. Forest Service. The area studied included the Borah Peak RARE II roadless areas (No. 14210, 119,864 acres of land recommended for wilderness designation; and No. X4210, 18,440 acres of land recommended as non-wilderness) and other contiguous Forest Service administered land. The study area is in Challis National Forest in southeast Idaho about 30 miles south-southeast of Challis, ID. Burnt Creek, a conterminous study area to the northeast, on lands administered by the U.S. Bureau of Land Managment, was examined concurrently. Dolomite and limestone inferred reserve bases exceed 1 billion tons each within the Borah Peak study area. The material is widespread and of high quality. Extensive sampling and more detailed mapping are required to better define the resources; however, ample dolomite and limestone occur nearby, outside the study area. Dolomite is the main constituent of several geologic formations within the study area. Sample analyses indicate that the more than 1,000-ft-thick Jefferson Formation dolomite is the most pure and is equivalent to material being mined at a dolomite-to-magnesium processing plant near Addy, WA. Analyses from limestone-bearing formations underlying much of the study area indicate that large quantities of the limestone may be suitable for a variety of uses.

Jan 1, 1987

By M. K. McCarter

Previous investigations suggest the possibility of determining shear strength of geologic materials by measuring the force necessary to rupture the web between two closely-spaced, parallel holes using a borehole jack. Current research using finite element modeling and laboratory testing of intact rock indicates that web failure initiates by tensile fracturing induced by a complex stress field. Based on these results, a theoretical justification for relating web strength with shear strength appears unlikely for holes of equal diameter spaced two diameters apart. Empirical results, however, show a strong correlation between average web strength and average unconfined compressive strength for some rock materials under laboratory conditions. A good correlation also exists between residual web strength and the residual angle of friction under the same conditions. This research project involves the construction and field testing of a large borehole jack. The jack is designed to operate within a conventional 12-1/4 inch rotary blasthole common to open pit mining. The system is capable of exerting approximately 800,000 pounds on curved platen measuring roughly 4x24 inches. Field tests indicate that the system will operate in a mining environment, and preliminary results suggest the possibility of using the force-displacement data generated by the jack to rank the competency of material within a mine bench.

Jan 1, 1982

By Kenneth G. Skinner

Diatomite, also known as diatomaceous earth, diatomaceous silica, kieselguhr, and moler, has been used extensively for many years, but only during the past two decades has it become an important industrial mineral. United States sales for 1.936-38 totaled almost 280,010 tons,7 but relatively little (with the exception of that sold by an Oregon company affiliated with a larger California company) was sold by Pacific Northwest producers. In attempting to develop some of the many Pacific Northwest diatomite deposits, these producers have been handicapped by lack of published technical information regarding processing methods and the suitability of different deposits for specific uses. To determine some of the physical and chemical properties of known Pacific Northwest diatomites, the present investigation was started in 1938 by the Bureau of Mines in cooperation with the College of Mines, University of Washington. Figure 1 shows the location of deposits sampled. Because most relatively pure diatomites can be used as concrete admixtures or as inert fillers in rubber, paints, and plastics, this investigation concentrated upon determining some filter-aid characteristics and their relationship to other physical properties. A filter-aid is a powdered material that, when added to solutions to be filtered, improves flow rate, filtrate clarity, or both. Some chemical analyses also were made.

Jan 1, 1944

By H. L. Riley

At the Southern Experiment Station, Tuscaloosa, Ala., reports are prepared from time to time on results of washability studies of coal from important beds in the Southern Appalachian region. The investigations that provide the material for these reports are made by the Bureau of Mines, United States Department of the Interior, in cooperation with the University of Alabama and the mine operators. The principal objective of a washability study is to obtain technically and commercially important data to aid in determining the best methods for preparing and utilizing the Nation's reserves, particularly of coking coals. Such information is also important from the standpoint of conservation, because it facilitates the selection of preparation methods that will yield an acceptable product with a minimum loss of coal to the rejects.

Jan 1, 1958

By Michael Zachariah, Art Miller, David Kittelson, Gib Ahlstrand

This report describes an investigation in which we used iron-doped diesel fuel to generate metal-bearing diesel particles and a subsequent analysis of the particles using transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS). For this study, DPM was generated by a 1.5-L diesel engine and the fuel was doped with ferrocene to enhance the level of iron in the system. The exhaust particles were collected on TEM grids and analyzed using the Philips CM12 TEM/EDS instrument. Results show that when the iron-to-carbon (soot) ratio (Fe/C) in the engine is low, the exhaust particles have morphologies similar to those for the undoped case, but at a threshold Fe/C value of 0.013 (for this engine), homogeneously nucleated metallic nanoparticles are formed and begin agglomerating. The number and size of these nanoparticles increase with level of doping. Metal-bearing particles that span a wider size range are also formed. Agglomeration of metallic and carbon particles is observed in two distinct modes: attachment of iron primary particles (5–10 nm in diameter) to carbon agglomerates, and coagulation of iron agglomerates (20–200 nm in diameter) with carbon agglomerates. Results of this work imply that as new engine technologies reduce soot levels in the engine and/or levels of trace metals in the fuel are increased, the generation of metallic nanoparticles may ensue, creating a potential health concern. Keywords: Nanoparticles; Particulate emissions; Metallic particles; Metal emissions

By J. R. Thoenen

In Progress Rerort 1,4/ a number of facto were demonstrated and conclusions drawn from experimental tests and records made during commercial blasting operations at a number of quarries. For example, the tests showed (1) that vibrations received on outcrops were of comparatively

Jan 1, 1938

By O. Q. Leone

Excellent metal quality, with lower power requirement, is attained in electrorefining titanium by using internal heating of the fused-salt bath. An internal heater provides more effective heat utilization, simplifies structural components in cell design, and prolongs cell life by eliminating direct application of heat to the cell container. This Bureau of Mines report covers one phase of the research in progress at the Electrometallurgical Experiment Station at Boulder City, Nev., for improving the techniques and lowering the total power requirement for electro-refining titanium metal.

Jan 1, 1959

By Arnold B. Hubbard

A thermal decomposition study of the kerogen in three Colorado oil shales was made at different temperatures by heating the shales in the absence of oxygen at atmospheric pressure and measuring the decomposition products (gas, oil, and bitumen) formed. From these data the specific reaction rates, "k", for the thermal decomposition of kerogen were determined for each temperature studied, making it possible to calculate the time required to accomplish a given amount of decomposition within the temperature range. The influence of temperature on reaction rates was presented by plotting the data according to the Arrhenius equation, thus providing a means of estimating the values of "k" for any temperature within the range of this study. It was found that the specific reaction rates for the thermal decomposition of the kerogen in the three sampler were comparatively equal at corresponding temperatures.

Jan 1, 1950

By L. G. Marshall

This report describes dredging and processing of sand and gravel from a glacial-fluvial deposit in the Raccoon River valley near West Des Moines, Iowa. Preliminary cleaning and separation of the sand and gravel at the dredge site with subsequent transportation to separate plants and the production and disposal of the various grades of aggregate material are also described. The geology of the deposit is summarized. A tabulated summary of costs in units of labor, power, and supplies is included.

Jan 1, 1963

By Keith L. Harris

Recent data indicate a marginal decline in overall growth in world economic output from 3.1% in 1985 to 2.9% in 1986 (table 1),2, 3 Many nations experienced slower economic growth because of the huge trade imbalances existing between the United [ ] States and Japan and the Federal Republic of Germany, the U.S. budget deficit, and the growing Third World debt. Some developing nations, however, experienced booming growth. Declining prices for energy and nonenergy commodities and the fall of the dollar against the currencies of major industrial countries benefited several developing countries--energy importers and exporters of manufactured goods with currencies tied to the U.S. dollar, which were able to expand markets in the industrialized nations. The drop in commodity prices increased demand in industrial countries and depressed it in developing countries. Lower demand in the developing countries contributed to a decline in the real net exports from industrial countries. As a result, output growth in industrial countries declined from 3.0% in 1985 to 2.4% in 1986, despite growing internal demand, Average output growth of developing countries increased from 3.296 to 3.596 during the same period, however, primarily because of the low prices of their products and the strength of demand in industrial countries for those products. Developed country output growth was extremely uneven, however. For example, the economic output of nonfuel exporters grew 5.4% in 1986, while that of fuel exporters dropped 0.7%.

Jan 1, 1987

By Leslie S. Rubin

A ventilated helical boost pump was developed that can handle varying flow rates and/or solids concentrations while operating at a single rotational speed and without computer assisted feedback controls. The boost pump developed and briefly tested during this program was designed to accomodate flows suitable for a 3-in. diameter pipeline. The boost pump's ventilated design provides the automatic pressure regulation needed to meet the system's requirements for supporting transient pipeline flow.

Jan 1, 1984

By R. H. Hiltz

The Coal Mine Health and Safety Act of 1969 legislated maximum dust levels for the working place. As the law was implemented, extensive efforts were undertaken to provide the technology necessary to control dust generation. One approach to dust control was the use of high expansion foam in place of the usual water sprays on coal cutting equipment. At the time of the act, high expansion foam had already seen considerable testing for the suppression of dust in underground coal mines. Work by MSA, several coal companies and the Bureau of Mines itself had provided data which showed foam to have some merit as a dust control mechanism. It suffered in a few areas, however, which limited its practical application. Its principal difficulty was persistence which hampered operations due to foam buildup, but problems were also encountered due to equipment size and form.

Jan 1, 1975

By L. C. IlsLey

Many accidents rightly classifiable as electrically caused are not so classified for the reason that in numerous accidents the part that electricity played in causing the fatality is only suspected. For instance, a workman might receive a shock that would cause him to lose his balance and fall beneath a trip of cars; if no one saw the first part of the accident, the cause undoubtedly would be charged to "haulage." This paper covers a brief study of fatal and nonfatal electrical accidents. The first usually result from direct contact with the electrical circuit or electrical apparatus; the second more often are the result of arcing or flashing due to handling defective apparatus or making repairs on "live" equipment or circuits. It is hoped that helpful suggestions may be offered for minimizing accidents of these two classes.

Jan 1, 1938

By D. J. Dollhopf

A week-long selective overburden handling dragline op ration was conducted at a strip mine near Colstrip, Montana. The objective of the demonstration was to hvdrologically isolate a saline overburden zone during placement in the spoil piles. The saline zone had concentrations considered inimical to successful reclamation and was potentially dangerous to future water quality in the spoils aquifer. The zone was identified after review of chemical data for overburden samples collected from the intense 60 m grid drilling pattern. The saline zone in the overburden was: 1) handled in a normal manner; 2) segregated and buried; and 3) segregated, buried, and covered with a relatively impermeable 1.0 m thick clay cap. The method used to formulate this demonstration, the demonstration itself, and the monitoring and evaluation techniques are described in this report. Observation wells were installed to monitor ground water in the overburden, Rosebud coal, and McKay coal. Data from these wells were, used to estimate post reclamation water levels and to evaluate recharge and water movement characteristics in the vicinity of the demonstrations. The inimical zone was successfully handled in a selective manner with a minimum of delays. Economic analysis indicated cost of these selective burial operations to be about 1.1 to 1.5 times the cost of the normal operation at this particular mine site. Long term monitoring will be required to evaluate the effectiveness of these handling techniques in hydrologically isolating undesirable overburden materials.

Jan 1, 1977

By L. B. Berger

Studies showing the effect of mixing hot exhaust gases with the intake air of a four-stroke-cycle Diesel engine are described. The results indicate a marked increase in carbon monoxide in tip exhaust gases, a decrease in oxides of nitrogen, and no significant effect on aldehydes. The increase in carbon monoxide was greater at higher fuel-air ratios and was caused partly by the increase in fuel-air ratio end partly by the decrease in oxygen concentration resulting when exhaust has was added. The application of these results to the use of Diesel engines underground is considered.

Jan 1, 1940