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By R. E. Heithecker

In Kansas, almost every oil well drilled into a limestone formation is treated with hydrochloric (muriatic) acid upon completion. This is done to increase the potential capacity of the well and thereby increase its "daily allowable" production (see p. 9), to shorten the time required to produce the recoverable oil, and to increase the quantity of oil recovered ultimately from the reservoir. The porosity and. permeability of limestone formations seldom are uniform throughout the proved area, consequently the production capacities of completed wells vary considerably. Acid treatment of wells tends to increase production capacity and to equalize potential capacity. If offset wells already have been treated with acid, new wells usually are treated to protect the property on which they are drilled against drainage. Even though competitive conditions do not exist in a field, it

Jan 1, 1939

1. Proposals were submitted to the Western Administrative Center of the US Bureau of Mines, Denver, Colorado on 30th December, 1974 and Contract No J 0255003 was awarded, the effective date being 8th May, 1975. Dames and Moore, Denver, are associated with PD-NCB Consultants in regard to environ-mental problems, surface mining practice and legislation in US. BACKGROUND TO THE STUDY 2. Under the threefold pressures of -increased domestic fossil fuel demand -increased value of domestic energy resources -increased demand for environmental protection and safety

Jan 1, 1976

By B. J. Arnold, F. F. Aplan

"The captive bubble and sessile drop contact angle techniques have been used to evaluate the hydrophobicity of petrographically identified coal macerals. The magnitude of the contact angle on vitrinite is shown to be a function of coal rank ( %C, %0 and % vitrinite reflectance), increasing with increasing rank to a maximum for low volatile bituminous rank coals then decreasing for anthracite. The least data scatter is found when vitrinite reflectance is used as a rank parameter. Contact angles measured or estimated for other discrete macerals, indicate a variation in hydrophobicity based on coal type. These data correlate well with known flotation results. Coal is a heterogeneous mixture of plant remains and associated minerals that have undergone chemical and physical changes by biological and geological processes. These plant remains form coal macerals, discrete organic entities in the coal which have characteristic chemical and physical properties. As the differing chemical nature of each maceral will affect its behaviour in processes such as carbonization the separation of macerals during coal preparation may provide an important asset in coal utilization.Separation of some of the macerals based on specific gravity has been achieved in the laboratory, and by Sun and Cohen , in a study of two Pennsylvania bituminous coal preparation plants. It was indicated that the lighter exinites report almost exclusively to the clean coal while the denser inertinites are concentrated in the higher gravity fractions. The Longwy-Burstlein process6 took advantage of the difference in hardness or friability of the macerals by using impact breakage followed by screening to remove the more friable vitrain,clarain and fusain. The remaining durain, often high in spore content, was then recrushed. The re-mixed fractions produced the optimum size for obtaining the best coke strength for a particular coal.Separation or concentration of rnacerals by froth flotation largely depends on differences in the hydrophobicity of the macerals. Sun and Cohen 5 . indicated an order of decreasing floatability as exinite, vitrinite and inertinite, while a Russian study (as cited by Brown 7 ) showed that vitrains floated more readily than the duller types. More recently, Hirt and Aplan8 showed that 'pseudovitrinite' floats somewhat faster than does vitrinite while fusinite floats very slowly. Olson and A plan found that vitrinite floated easily while substantial quantities of the non-floated coal contained fusinitic material. Burdon noted that vitrinite is more floatable than semifusinite, and Sarker et a/. 11 have shown that vitrinite is selectively concentrated by froth flotation and oil agglomeration. Sun indicated that flotation, based on his calculated floatability index, should decrease in the order clarain, vitrain, fusain and durain; while Horsley and Smith 13 indicated the decrease to be: vitrain, clarain, durain and fusain. These differences can be attributed to the specific coals used in each study and to the individual macerals composing each coal type within a given coal."

Jan 1, 1989

By Herbert H. Einstein

The thrust of research reported in Part I was to collect in-situ data from exploration programs and the published literature, and to empirically establish distributional patterns for these variables. Since discontinui¬ties in a rock mass govern to a large extent its engineering properties and thus the performance of any slope in the mass, work has been devoted to determining the appropriate distributional forms for attitude spacing and length of discontinuities and to distributional properties of resis¬tance and deformability parameters. The conclusion from these analyses is that trace lengths are logNormally distributed and that joint spacing is Exponentially distributed, regardless of orientation of the sampling line, and regardless of whether each joint set is considered separately or not. Joint orientation (attitude) data representing 22 individual joint sets from eight sites (a total or approximately 20,000 joints), do nor strongly support any of the commonly used distributions as broadly applicable in practice. The autocorrelation )f geometric joint properties is also examined. However, no significant spatial correlation could be found even after extensive data manipulation. The investigation of resistance and deformability parameters starts with a review of mechanisms and models that are used to represent them. Review and statistical evaluation of approxi¬mately 2,000 discontinuity shear tests has shown that good statistical estimates for use in reliability analyses can be obtained for friction angles.

Jan 1, 1979

By James S. Wroth

The Act of Congress approved June 25, 1926 (Public Act 424, 69th Congress), authorized joint investigations by the U. S. Geological Survey and the U. S. Bureau of Mines to determine "the location, extent, and mode of occurrence of potash deposits in the United States." The particular deposits selected for exploration were the extensive rock-salt formations underlying large areas in western Texas and southeastern New Mexico, from which potash salts had been identified in the cuttings and sludges from oil wells drilled with cable tools. The evidence of these sludge samples was qualitative only and beyond definitely proving the presence of potash salts in the salt beds, gave little clue to the possible size, richness, or extent of the potash occurrences.

Jan 1, 1929

A compilation of papers presented at the Fifth WVU Conference on Coal Mine Electrotechnology in Morgantown, West Virginia, on July 30, 31, and August 1, 1980. Papers cover areas of electromagnetics/power systems, power systems, monitoring and control, and communications.

Jan 1, 1980

By Clayton R. Morlock

Airblasts have been monitored at four coal strip mines and at a limestone quarry. Thirty-seven production blasts have been monitored with three seismographs, resulting in one hundred and eleven complete air pressure records. Instrumentation selection use is described. Data analysis includes an assessment of the predictability of peak overpressures by means of the cube root scaled distance law. It is found that predictability for the cases studied here is not good. An extensive discussion of possible explanations is included. A detailed analysis of the frequency content of the observed airblasts, of considerable importance in evaluating potential annoyance problems, has been made for all records. A computer program has been written to simulate airblasts induced by multiple-hole blasts. A series of small experimental blasts have been detonated and monitored in order to allow an assessment of the program. It is clear that airblasts, especially when induced by very small charges and monitored at very close distances, are highly sensitive to detonation times. Retrofitting of airblast records occasionally was possible, but considerably improved field work is required to validate or refute the computer model.

Jan 1, 1983

This report provides the results of an industrial engineering study that assessed the safety and efficiency of underground ore handling in U.S. metal mines. One of the primary findings of the study was the improvement needed in controlling muck size in the ore handling stream. Oversize ore causes much additional labor, creating work stoppages and is a principal cause of accidents in metal mines. This report includes data on block caving, back cut and fill room and pillar, shrinkage stoping, and sublevel stoping.

Jan 1, 1974

By David E. Van Dillen

The computer program described in this user's guide provides for the static, three-dimensional, linear and nonlinear analysis of structural and geological systems by the finite element method. The guide describes the capabilities and general features of the program and shows how input is prepared. A number of recent advances in finite element theory and computer technology are incorporated in the program. Nonlinear material properties are provided for, including isotropic, anisotropic, and time-dependent material properties, gravity loading, simulation of a sequence of excavation or construction, and a slip or joint element. The finite elements include beam, rod, axisymmetric and plane quadrilateral, hexahedron, thick shell, axisymmetric and plane joint, and a three-dimensional joint. The program also has an automatic mesh generator to minimize user input preparation for continuum finite element meshes.

Jan 1, 1981

By Margaret R. Egan

A series of experiments were undertaken by the Bureau of Mines to determine the emission products of several types of conveyor belting and other combustible materials found in mines. These experiments were conducted under intermediate-scale, simulated mine conditions to determine smoke characteristics and gas concentrations. From these determinations, heat-release rates, particle sizes, obscuration rates, combustion yields, and production constants were calculated. Three types of belts were investigated: chloroprene, also known as neoprene (NP); polyvinyl chloride (PVC); and styrene-butadiene rubber (SBR). The belts were designated as ignitable or self-extinguishing depending on the length of the burning time and the subsequent combustion products. Under these experimental conditions, the SBR belts were the easiest to ignite. The PVC and NP belts tended to self- extinguish within a few minutes after ignition, but were still capable of maintaining a brief flaming period. These conveyor belt combustion results are compared with previous analyses of wood, transformer fluid, and coal fires. Together they form a data base by which findings from future experiments with other mine combustibles can be compared.

Jan 1, 1988

By Arel B. McMahan

The U.S. Bureau of Mines investigated 21 mines, prospects, and mineralized sites in and adjacent to a 38,713-acre portion of the 255,058-acre Kingston Range Wilderness Study Area in 1983. The study area is 35 miles north of Baker, CA in the Mojave Desert. Mineral deposits in and adjacent to the study area are in altered carbonate rocks intruded by diabase sills near monzonite porphyry contacts. Monzonite porphyry forms the core of the Kingston Range and underlies about 70 percent of the study area. Sedimentary carbonate rocks are exposed in bands on the north and east boundaries and as isolated roof pendants in the southeastern portion of the study area.

Jan 1, 1986

By Scott A. Stebbins

This Bureau of Mines publication presents a method for estimating capital and operating costs associated with the exploration, mining, and processing of placer deposits. To ensure representative cost estimates, operational parameters for placering equipment and basic principles of placer mining techniques are detailed.

Jan 1, 1987

By William J. Krisko

This contract final report summarizes the design, fabrication and testing of a "line brattice air curtain" device under Bureau of Mines Contract H0357097. The purpose of this program was to develop the concept of using an air curtain for coursing ventilating air parallel with the air curtain From the last open crosscut to the face in exhausting ventilation systems to replace the line brattice cloth in room and pillar coal mining operations. The final design of the air curtain device consists of a 10-foot long closed end pipe with c: slot cut along its length. Pressurized air is delivered to the open end with a hydraulically-driven blower. A sheet of air emanates from the slot and is directed toward the mine roof. An invisible sheet of air is thus created between the top of the machine and mine roof and acts a an extension of the existing conventional line brattice.

Jan 1, 1977

By Sigmund Black

Ingersoll-Rand Research, T n c and the Lee-Norse Co. built a Bureau of Mines sponsored, special deep cutting continuous miner under this contract to study the effects of rotational speed and depth of cut on airborne respirable dust. After preliminary tests indicated and later verified that deep cutting - low rotational speed reduces airborne respirable dust, a series of underground tests were performed (9 combinations of rotational speed and depth of cut at 45° bit angle and 4" bit spacing). Additional data was obtained on specific energy, coal sizing and noise. The conclusions reached from the tests results were; a) deep cutting reduces airborne respirable dust generated and specific energy needed to cut coal., b) the greater majority of the decrease occurs in going from 1" to 2" depth of cut, c) lowering rotational speed has a particularly sizable effect of reducing the amount of dust at the operator's location, d) no significant relationship was found for either noise level or coal sizing to rotational speed or depth of cut. Recommendations include. a)) use of specific energy as an indicator of the change in dust level correlating to changes in cutting parameters, b) mine operators should acquire new deep cutting machines., since retrofitting would be selective.

Jan 1, 1977

By Stanton L. Tainter

As a part of a wartime program to aid in the development of known ore bodies and in the discovery of hitherto unknown deposits of strategic minerals, the Bureau of Mines investigated the feasibility of diamond-drilling the Christmas copper deposit, in Gila County, Ariz., to increase the reserves of milling ore. Upon recommendation of the examining engineer, drilling was begun in September 1942, from the bottom (770) level of the mine. One month later, in cooperation with the Bureau, the Federal Geological Survey started geologic mapping of the mine workings. Since extensive and costly development would be required, the War Production Board concluded that ore below the bottom level could not be mined at that time because of the wartime shortages of equipment and man-power. In January 1943, drilling was moved to the 300 and 400 levels to locate reserves readily accessible for continued production of fluxing ore. This drilling, which was under the supervision of L. G. Marshall, was completed in January 1944.

Jan 1, 1948

By M. H. Kline, T. J. Ballard

"INTRODUCTION The Cranberry magnetite deposits occur in pre-Cambrian granite-gneiss in a belt extending from 3 miles southeast of Cranberry, N. C., to about 6 miles southwest of Magnetic City, Tenn. The belt forms a curve, elongated to the north, approximately 26 miles in length.The Bureau of Mines investigation has been confined to the eastern part of the belt, comprising the area from Fork Mountain, Avery County, N. C., to the Hcupscup Knob prospects in Carter County, Tenn.The deposits were worked at least as early as 1820. The Cranberry Iron & Coal Co. and its successors operated the Cranberry mine intermittently for about 50 years until 1930, when operations were abandoned.The magnetite rock is amenable to concentration. Numerous laboratory tests and pilot-mill operations have proved that a high-iron, and low-phosphorus concentrate can be obtained by fine grinding and magnetic, separation, the quality of the concentrate depending upon the extent of grinding. The principal objectives of the Cranberry project were threefold.The primary consideration for beginning exploration of the deposits was the need for developing additional deposits of high-grade iron ore during the war and for replenishing the war's depletion of iron-ore reserves for the peacetime economy. The emergency did not permit logical sequence bf development, and it was necessary to begin drilling before the geophysical survey was completed. The first drilling was begun at the Cranberry mine; and the holes were located from the geological data, coordinated with the position of the mine workings."

May 1, 1948

By Wilson Blake

This report presents the results of a 7-year Bureau of Mines program to review, revise, and make an effective engineering tool of the microseismic method of determining the stability of rock structures. The program consisted of developing new microseismic equipment and data analysis techniques and extensive field investigations to demonstrate the effectiveness and potential of the broad-band microseismic method. The guidelines for choosing the components of a microseismic system are presented along with approximate cost figures. Different microseismic systems are discussed, including completely automated systems. Procedures for conducting microseismic investigations and analyzing microseismic data are discussed in detail. Field situations which show the full value of the microseismic technique as an engineering tool are described.

Jan 1, 1974

By William J. Campbell

Three types of X-ray analytical instrumentation were compared for applications in the secondary brass and bronze industry. The instruments were a conventional X-ray spectrograph, a portable X-ray spectrograph, and a radioiso-topic X-ray analyzer using balanced filters. The following two general applications were considered: Rapid identification for sorting scrap metals and quantitative analyses to provide guidance in the melting and casting of alloys. Twenty-three analyzed copper-base alloys were used as standards. Although the alloys varied widely in composition, matrix correction procedures were not necessary except for copper. The conventional X-ray spectrograph provides positive identification of the alloys and quantitative values for the six elements investigated--aluminum, copper, iron, lead, tin, and zinc. Equivalent results were obtained with the portable X-ray spectrograph for those elements whose characteristic X-rays are in the wavelength range of the instrument. The radioisotopic X-ray analyzer distinguishes certain groups of alloys and provides quantitative determinations for copper, lead, tin, and zinc. The sensitivity of the analyzer was marginal for the determination of small concentrations of elements of atomic number 26 or lower.

Jan 1, 1972

By Jay C. Hanson

Various electrical and electromagnetic (EM) geophysical techniques are currently being evaluated by the U.S. Bureau of Mines for their effectiveness in the detection and monitoring of electrically conductive (1 to 5 S/m) lixiviant (leach solution) to depths of 600 m, either above or below the water table. These techniques include magnetotellurics (MT) , controlled source audiofrequency magnetotellurics (CSAMT), resistivity and focused resistivity, ground-penetrating radar (GPR), frequency-domain electromagnetics (FEM), and time-domain electromagnetics (TEM). Of these techniques, TEM may be the most effective, but CSAMT and focused resistivity also hold promise. Geophysical computer modeling of the borehole TEM technique was conducted based on an idealized geoelectric section (layered earth) with characteristics based on the Santa Cruz porphyry copper deposit near Cas a Grande, AZ. Layer resistivities and thicknesses were obtained from geophysical data and geologic logs available from the site. Modeling of borehole TEM in both preleach and during leach situations was conducted. Simulating the TEM method using computer modeling proved to be encouraging since there were substantial differences between leached and nonleached responses. The modeling does not prove the effectiveness of TEM in the field, but does indicate that detection of deep lixiviant zones is theoretically possible.

Jan 1, 1992

By D. K. Ingram, P. Jurovcik

The National Institute for Occupational Safety and Health (NIOSH) identified hearing loss as the most common job-related disease in the United States in its 1996 National Occupational Research Agenda. Previous studies by NIOSH have shown that operators of surface drill rigs without cabs are commonly exposed to A-weighted sound levels exceeding 90 dB. During hammer-drilling, A-weighted sound levels exceeding 100 dB were recorded at the operator station. NIOSH collaborated with a local drilling company to design and install a partial cab between the operator and the drill steel in an effort to reduce the sound level at the operator station. Sound level measurements in the field show the partial cab reduces the A-weighted sound level by 5 to 9 dB at the operator’s left ear and 2 to 5 dB at the operator’s right ear while hammer-drilling. This paper briefly discusses the preliminary design of a cab and the testing of materials for construction of the prototype. An explanation of the ideas behind the prototype design and fabrication are covered. Finally, the field test method and results are discussed in detail.1