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By Anthony T. Xannacchione, Luis E. Vallejo

At present, there is little knowledge concerning the shear strength of clays containing floating rock particles with concentrations from 0 to 30%. In practice, the effect of rock particles is typically disregarded in shear strength analysis The two primary reasons for this are: 1) a lack of agreement concerning the influence of rock particles on material strength, and 2) the expense and difficulty of testing day-rack mixtures with existing laboratory procedures. These factors have impeded the development of successful slope remediation design techniques far colluviums derived from resistant sedimentary rocks or spoil produced from surface mining. This study reviewed 3 1 technical papers which contain analysis of shear strengths for clay and sands with varying mixtures of rock particles. These technical papers, published over the last 40 years, are comprised of field case studies, laboratory evaluations, and theoretical analysis. Evaluation of this body of knowledge ha shown that the shear strength gradually increases with increasing percentages of floating particles in unsaturated clays.

By Lucia Kuizon

The Pinnacles Wilderness Contiguous Wilderness Study Area (WSA) (CA-040-303) is 30 miles south of Hollister, CA, in San Benito and Monterey Counties. It is composed of five parcels of public land totaling 5,838 acres adjacent to the Pinnacles National Monument. The U.S. Bureau of Land Management later reduced the size of the Recommended Suitable Area (RSA) to 2,200 acres. U.S: Bureau of Mines personnel examined the entire WSA in May 1984. The WSA is underlain by Tertiary sedimentary and Cretaceous plutonic rocks. Diatoms occur in interbedded tuff, shale, and sandstones in the northern part of the WSA, but outside the RSA. In 1984, there were no mines, prospects, mining claims, leases, or mineral resources in or within one mile of the study area. No energy minerals were identified; however, an oil well was drilled in 1951 in the northern part of the WSA, but outside the RSA; it was a dry hole.

Jan 1, 1985

Coal mining in Indiana is limited to the south-western portion of the state, with coal currently being recovered in 19 counties. The coal-producing area of the state covers approximately 6,500 square miles. Although most of the coal in Indiana is recovered by surface mining methods, a small percentage is recovered through underground mining. To date, 40 percent of the known coal reserves have been removed. Indiana has about 33 billion tons of identified coal reserves, of which approximately 17 billion tons are recoverable using current technology. Of this recoverable coal, about 15 billion tons are recoverable by underground mining and 2 billion tons are recoverable by surface mining methods. The State of Indiana has regulated the environmental impacts of coal mining since 1941. Indiana was the second state in the nation to pass legislation requiring mined land reclamation. Its SMCRA regulatory program was approved July 29,1982, and its Abandoned Mine Land Program was approved July 29, 1982.

Jan 1, 1992

By Alla D. Mah

The need for more and better basic thermodynamic data for the oxides of many of the rare metals is evident to anyone who attempts thermodynamic calculations involving these substances. In continuation of a Bureau of Mines program to meet this need, this paper reports new experimental values of the heats of formation at 298.15° K. of the hexagonal crystalline variety of germanium dioxide and germanium dioxide glass. The values were obtained by means of combustion calorimetry and sodium hydroxide-solution calorimetry. The calorimetric results also made possible the derivation of values for the heat and entropy of fusion of hexagonal germanium dioxide at its melting point. The newly measured data were combined with previously known entropy and high-temperature heat content values to obtain heats and free energies of formation of germanium dioxide (in the hexagonal crystalline, glassy, and liquid states) over the temperature range from 298.15° to 2,000° K.

Jan 1, 1962

By H. B. Carroll

The performance of commercially available portable instrumentation for detecting nitrogen dioxide, sulfur dioxide, and hydrogen sulfide was evaluated. Length-of-stain detector tubes from several manufacturers were included in the study. The instruments were evaluated in atmospheres with 50-and 80-percent relative humidities at 75° F and containing test gas concentrations of 0.1, 0.25, 0.50, 1.0, 1.5, and 2.0 times the threshold limit values. The results from the gas analyzers were correlated with the known contaminant concentration by calculating and plotting an estimated line of regression, confidence limits, and correlation coefficient for each detector system. An increase in the relative humidity from 50 to 80 percent at /5° F changed the instrument response to the contaminants. The uncertainties in detection precision reported are for the observer-instrument system. The main difference or inconsistency in toxic gas concentrations determined with length-of-stain tubes resulted from the observer's interpretation of the results rather than from a predominant difference in the tubes.

Jan 1, 1975

By W. W. Adams

Rock dust, as a preventive or limiting factor in explosions of gas and coal dust in bituminous-coal mines, was used in larger quantities in 1939 than in any other year except 1937 since annual figures first became available in 1930, Reports from mining companies to the Bureau of Mines revealed that 144,430,000 pounds of rock dust was applied to underground mine workings in mines that produced 126,635,677 short tons of coal during the year. This quantity of rock dust applied averaged 1.14 pounds for each ton of coal produced. Rock dusted mines were the source of 39.7 percent of the total production of bituminous coal from underground mines; 33.2 percent of the total number of underground workers were employed at rock-dusted mines, and 35.9 percent of the total number of man-hours worked underground at all bituminous-coal mines in the United States during 19719 can be accredited to mines so treated.

Jan 1, 1940

By Roy L. Wilfong

The thermal decomposition of the ammonium sulfate, carbonate, nitrate, oxalate, and sulfate salts of praseodymium, neodymium, and samarium was investigated thermogravimetrically in the temperature range 25° to 1,500° C. Each salt was decomposed at a heating rate of 2.5° C, per minute. The pyrolytic sequences have been identified and the temperatures of formation of inter-mediates, the minimum oxide formation temperatures, and values for loss on ignition have been determined. The nonstoichiometric ranges between Pr6011 and Pr203 and the extent of these ranges have been determined for oxides derived from the carbonate, nitrate, and oxalate salts of praseodymium. The alum and sulfate salts of praseodymium produced the sesquioxide without forming the intermediate non-stoichiometric oxides. The temperature limits of formation and regions of stability for the alums and sulfates were better defined than were those for the carbonates, nitrates, and oxalates. The minimum oxide formation temperature increased in the order of samarium, neodymium, and praseodymium irrespective of the anion.

Jan 1, 1962

By William M. Schafer

Forage plots were established on agricultural lands contaminated by acid mining waste. The acid produced through oxidation of pyrite and other sulfides caused elevated solubility and plant availability of copper, zinc, and arsenic which killed vegetation and polluted surface and groundwater. Soil amendments including agricultural lime (CaCO3), hydrated lime (Ca(OH)2), phosphorus, and organic matter were used to reduce the toxicity of metals. Several acid-tolerant grasses were used to vegetate the amended soils. Various soil extraction techniques were used to see which best correlated with vegetation performance. The extractions corresponded to three "forms" of metals in soil including soluble (water-saturation extract); plant-available/weakly adsorbed (DTPA extract); and total (HNO3/H202 extract). Of the extractants tested the DTPA levels appeared to correlate best with metal levels in plant tissue. The DTPA soil extractant serves as a useful tool in predicting potential phytotoxicity of mine waste materials.

Jan 1, 1989

By Herbert H. Einstein

Instability of rock slopes often occurs in the form of excessive movement of bodies that are bounded by discontinuities. The well known limit equilibrium analysis for wedges and blocks suffer, however, from procedural simplifications and from the basic deficiency of limit eguilibrium analysis--the rigid body assumption. Thus, stability analysis for 2-and 3-plane wedges with a wide range of additional features regarding failure modes and external forces have been developed. The deficiency, due to the rigid body assumption, was corrected by an approach that includes the effects or the in-situ stress field and of the stiffness of discontinuities. The final step in making limit equilibrium approaches more valid was achieved with the method of artificial supports which makes it possible to identify among all possible failure modes the critical one and to determine the corresponding factor of safety. The analytical development includes the creation of appropriate computer codes and routines for programmable pocket calculators.

Jan 1, 1979

In the interest of safety in mining, the Bureau of Mines recommends: 1. That cages or skips used for hoisting or lowering men in vertical and steeply inclined shafts shall be provided with safety catches designed to prevent falling of the cage or skip if the hoisting rope or other connections break; and 2. That cars used. for hoisting or lowering men with ropes in slopes shall be provided with arresting devices, other than ordinary brakes, that come into action if the hoisting rope or other connections break. In presenting this decision, it is recognized that the principal requirements for safety in hoisting operations are the use of hoisting ropes of ample size and strength to provide a factor of safety recognized as adequate by the best en engineering practice; their proper care, protection against undue wear and corrosion, and frequent inspection; and immediate removal of ropes from service when inspection or tests cast doubt upon their further safe serviceability.

Jan 1, 1938

By Gerald T. Homce, James C. Cawley

Problem: CFOI and SOII data show that 2,287 U.S. workers died and 32,807 workers sustained days away from work due to electrical shock or electrical burn injuries between 1992 and 1998. Method: The narrative, work activity, job title, source of injury, location, and industry for each fatal electrical accident were examined. A primary causal factor was identified for each fatality. Results: Electrical fatalities were categorized into five major groups. Overall, 44% of electrical fatalities occurred in the construction industry. Contact with overhead power lines caused 41 % of all electrical fatalities. Discussion: Electrical shock caused 99% of fatal and 62% of nonfatal electrical accidents. Comprising about 7% of the U.S. workforce, construction workers sustain 44% of electrical fatalities. Power line contact by mobile equipment occurs in many industries and should be the subject of focused research. Other problem areas are identified and opportunities for research are proposed. Impact on Industry: Improvements in electrical safety in one industry often have application in other industries.

By R. L. Rankin

The program objective was to conduct surveys of respirable dust concentrations in coal mining operations at locations outby the working face. The results of these surveys were directed toward 1. identifying outby dust sources, 2. evaluating the severity of the major dust sources, 3. establishing dust sampling frequency, 4. establishing dust sampler locations, and 5. assessing the? areas of influence of the dust sources. The study included dust sampling of only nonhigh risk personnel and areas at six dif-ferent mines. Thirteen continuous mining, four longwall and two conventional mining sections were sampled. The severity of outby respirable dust sources such as load points, runways, dump points, beltways, transfer points and main haulage operations were characterized and areas within the mine were ranked according to severity. Information on engineering controls was also acquired. Guidelines for implementing a dust sampling program are presented and include sampler locations, ventilation surveys, dust surveys, effects of shift-to-shift variations, and sampling frequency.

Jan 1, 1980

By Fermont F. Clarke, Others, Paul Zinner

"INTRODUCTION The Edison mine comprises workings on two irregular spodumene-bearing pegmatite dikes which outcrop near the town of Keystone in the southern portion of the Black Hills of South Dakota. The Bureau of Mines conducted an investigation of the Edison mine as part of a comprehensive study of the lithium mineral-production possibilities in the Black Hills area. The work was undertaken during the Second World War, when the demand for certain lithium salts and compounds exceeded the then small productive capacity of the industry.During the course of the project, the Bureau of Mines completed 13 diamond core-drill holes, aggregating 2,114.5 feet of drilling. Twenty-six cannel samples were taken from the main Edison shaft, and 13 miscellaneous samples were obtained to permit analysis of the efficiency of phases of mining and sorting operations. Metallurgical tests were made by the Bureau of Mines to investigate the feasibility of beneficiating spodumere-bearing ores from the Edison mine. 3/"

Apr 1, 1948

By R. C. Annear

This report describes open, sublevel, and shrinkage stoping at the Greenwood mine, operated by Inland Steel-Co. The iron ore mine is in Marquette County, Mich., about 6 miles southwest of Ishpeming (fig. 1). The Greenwood is one of three active underground hard-ore mines on the Marquette range, the others being the Cliffs-Shaft and the Champion mines. The operation reflects an achievement in exploiting small, difficult-to-mine hard-ore bodies lying beneath a 200-foot overburden of glacial drift, which is partly water bearing. This report can indicate only briefly the efforts of personnel in overcoming adverse conditions in mining more than 2 million tons of ore, 80 percent of which was in lump form, for open-hearth production of steel. Significant data presented include descriptions of the principal mining methods employed, sublevel and shrinkage stoping; percent aged mining costs for the entire year 1957, covering both direct mining costs and general expenses; and performance records in units of labor, power, and supplies.

Jan 1, 1960

The extremely cold weather and heavy snowstorms of January and February in northeastern Pennsylvania--with frozen mining equipment, diminished preparation and lack of railroad cars--severely hampered the production and distribution of anthracite. As a result, the previous estimates for the 2 months have been revised. On March 1, 1977, at the Porter Tunnel of the Kocher Coal Company at Tower City, Pa., an underground flash flood, which apparently broke through the wall of an adjoining abandoned shaft, swept through the mine. As of March 9, 1977, four miners were reported killed, three injured, and five trapped in the wreckage. The Kocher Coal Company began operations at the Porter Tunnel in 1968 and has had no fatalities until this current tragedy. The mine employs 20 persons on the surface and 115 miners underground, producing 750 tons of coal per day. Of the 109 underground mining operations in the anthracite region, this is the one remaining large mine that employs over 100 men.

Jan 1, 1977

By Frank E. Williams

This Bureau of Mines report describes 147 known fluorspar deposits in New Mexico and briefly mentions 54 miscellaneous occurrences for which little or no information was obtained. Most miscellaneous occurrences are minor and too poorly exposed to be considered more than prospects. History and production of fluorspar in New Mexico, type of deposition, mineralogy, uses, and grade specifications are discussed. Total mine production of fluorspar in New Mexico is nearly 641,000 tons of various grades of crude ore and hand-sorted material. Fluorspar deposits occur in 13 of the state's 32 counties. Grant, Valencia, and Luna Counties account for 86.4 percent of the total production. During the investigation, 141 deposits were visited. A total of 72 character samples was collected for assay, and 3 larger samples were collected for bench-scale metallurgical tests. Results of these metallurgical tests indicate that an acid-grade product can be obtained with 95 percent recovery of the CaF2 content of the crude ore.

Jan 1, 1966

By Terry J. Close

Between 1986 and 1989, at the request of the U. S. Bureau of Land Management, personnel from the U. S. Bureau of Mines Western Field Operations Center studied the highly-mineralized, 25,335-acre, Crack Canyon Wilderness Study Area (UT-060-028A), to evaluate its identified mineral resources. The 16-mi-long, 2-mi to 4-mi-wide stud/ area is on the southeast side of the San Rafael Swell, about 40 mi southwest of Green River, Emery County, southeast-central Utah. The study area is underlain by Mesozoic sedimentary beds. Uranium, the principle mineral resource, occurs in two formations. The principle uranium deposits are in mudstone, sandstone, and conglomerate lenses in the 22-mi-long outcrop of the Triassic Chinle Formation which parallels and straddles the northwest boundary of the study area, Some small low-grade uranium occurrences and an extensive gypsum deposit are hosted by the Jurassic-age rocks that underlie the southeast part of the study area.

Jan 1, 1989

By E. D. Calvert

As part of its goal to minimize the requirements for critical and strategic minerals, the Bureau of Mines is conducting research to foster the use of domestically abundant materials such as molybdenum. This report describes the development of an investment shell molding technique that can be used to make castings of molybdenum and its alloys. The mold material is cubic Zr02 with a monoclinic Zr02 binder. The shell, formed by standard investment molding techniques described in the text, is prepared for molybdenum casting by firing for 6 hours at 1,550° C (2,822° F) or for 4 hours at 1,650° C (3,002° F). The resulting castings have predictable and reproducible dimensions with good detail. As-cast strength is poorer than the strength of wrought materials below 1,600° F. At and above this temperature, tensile strengths of cast and wrought materials are nearly equal. Aqueous corrosion of the castings in most media is insignificant.

Jan 1, 1982

By Robert S. Warfield

The Federal Bureau of mines and U.S. Geological Survey conducted exploratory investigations and geologic mapping in the Wishbone Hill district of the Matanuska coalfield almost continuously from 1942 through 1958. These investigations delineated reserves of high-volatile bituminous coal necessary to supply the rapidly expanding military and civilian requirements in the Anchorage area. This report describes the program conducted by the Bureau of Mines from 1949 through 1958, and briefly summarizes previous investigations, the results of which have already been published. The coal-bearing structure on both the north and south limbs of the prominent Wishbone Hill syncline was explored by 8,719 feet of churn drilling and 25,460 feet of diamond-core drilling. A total of 33 holes were drilled ranging in depth from 60 to 2,114 feet. To supplement the drilling operations, bulldozer and dragline trenching were undertaken at key locations; about 25,000 cubic yards of dragline trench were excavated in the vicinity of the old Premier mine.

Jan 1, 1962

By Krishna P. Sinha

An investigation was made to determine the creep behavior of oil shale at elevated temperatures. During the first phase of the investigation, work done on creep behavior of geologic materials was reviewed and triaxial creep tests on oil shale were planned. Tests at temperatures up to 250°C and axial stress up to 3000 psi were conducted at no confinement and at confining pressures equal to 1/3 and 2/3 of axial stress. Wide variations in the elastic properties as well as creep characteristics are exhibited. Creep deformation is more pronounced at elevated temperature but no definite quantitative remarks can be made regarding effect of grade of oil shale due to wide scatter and limited number of data paints. Primary creep can be described by a power law. Secondary creep seems to be an experimental function of deviatoric stress. Teritary creep was not observed within the test duration (24 hours in most tests).

Jan 1, 1983