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By L. L. Rethi

The U.S. Bureau of Mines summarized injury data for independent contractor employees working at all locations of coal and metal-nonmetal mines from 1983 through 1990. During the eight years, the greatest contrast in degree of injury between independent contractor and operator employees was in fatalities. From 1983 through 1990, there were 132 independent contractor employee fatalities in the mining industry. In 1988 though, independent contractor employees accounted for nearly one-fourth of all mining fatalities. The fatality incidence rates of independent contractors were consistently higher than those of operators during the eight years. For instance, in 1990, the contractors' rate was twice that of operator employees in coalmining and nearly five times that of operators in metal-nonmetal mining. Three other salient facts highlight the independent contractor employees' fatality injury data during these years. First, 82% of the independent contractor employee fatalities occurred at surface locations. Second, two job classifications?truck driver and equipment operator?represented 37% of the fatalities throughout the 8-year period. And finally, four accident classifications?powered haulage, slips and falls, machinery, and electrical?accounted for 71% of all independent contractor employee fatalities.

Jan 1, 1993

By Levent Ozdemir

The results of a laboratory research program aimed at the development of a water jet assisted drag bit cutting system for coal mine applications are presented. Two types of drag bits, a conical and a plow bit, were tested in a hard sandstone rock with jet pressures of up to 20,000 psi. Jet locations investigated were in-front and behind the bit. For each jet mounting location, three jet impingement distances with respect to bit tip were tested. The closest jet impingement location to bit tip was found most effective, providing the greatest force reductions on the bit. Overall, significant bit force reductions up to 50 percent were obtained with jet assist. Also observed was a drastic reduction in airborne dust when jets were employed.

Jan 1, 1986

By M. H. Chetrick

An important factor in the design and operation of a lignite-gasification plant is knowledge of the thermal requirements. These not only vary with different-size plants but also with the operating conditions for a plant of given capacity. Thermal data have been collected since 1945 from a commercial-scale lignite-gasification pilot plant operated by the Bureau of Mines at Grand Forks, N. Dak. The description and operation of this plant and a study of the gas-composition data have already been described in previous reports (1, 2, 3, 4, 5).2) / This investigation was made to review the thermal data taken in tests and to correlate them in terms of the fraction of undecomposed steam and the H2:CO ratio.

Jan 1, 1953

By Peter L. Swanson

This investigation, which began 90 minutes after the February 3, 1995, seismic event, has benefitted from the assistance of a large number of individuals. These individuals provided information, data, analysis, brainstorming opportunities, field equipment, assistance with communication, conducted rock mechanics tests, and provided insight into mining in the southwestern Wyoming trona district. They include Rich Hodgson, Ron Hughes, Larry Refsdal. Mike Weller, John Kolesar, Joe Vendetti, and Rick Casey (Solvay Minerals), Dave Delling (Solvay consultant - former Solvay President), Karl Zipf (formerly with USBM, now with MSHA), Bob Friend, Bob Ferriter, Dave Ropchan, Jerry Davidson (MSHA Tech Support), Don Stauffenberg, Ben Hohler (Wyoming State Mine Inspector's office), Bruce Presgrave (USGS/NEIC), Chris Wood, Dan O'Connell (Bureau of Reclamation), Sue Nava, Jim Pechmann (University of Utah), John Norgord and members of FMC's mine rescue team (FMC Corp.), Bill Walter (Lawrence Livermore National Laboratory), Ron Gerlick, Kevin Wood, and Mike Harmel (USBM rock mechanics lab), Jim Case (Wyoming State Geological Survey), and Solvay consultants. In addition, many individuals helped us gather information on other recent large mining-related seismic events in Germany, Russia, and Australia. and other parts of the United States. These individuals include Wolfgang Minkley (IfG Institut fur Gebirgsmechanik, Leipzig), Arnfinn Prugger (Potash Corp. of Saskatchewan), Hartmut Spetzler (University of Colorado/ University of Bayreuth), Sergei Stanchits (Ioffe Poly-technical Institute, St. Petersburg), Rocky Thompson (Cyprus-Amax) and numerous seismologists throughout the Internet.

Jan 1, 2011

By H. Netuka, J. V. Horak, A. W. Khair

"A general review of major problems concerning mathematical modelling of roof bolting problem is given. A mathematical model (MM) of interactive set Bolt - Resin - Rock and its discretization based on the Finite Element Method (FEM) is developed to calculate numerically course of displacement, stress and strain fields in this set. This new MM enables to get also course of the normal and tangential components of contact stress vector, normal displacement and then mutual tangential slip at the bolt - resin and resin - rock interfaces, respectively.Behavior of system on all interfaces is modelled in the MM as a ""unilateral contact"" governed by so called non-classical boundary condition of Signorini's type including Coulomb's law of friction between resin and rock, and ""a given friction"" law between bolt and resin (see Duvaut, Lions (1972) for mathematical formulation).Numerical example and some values of resulting stresses are shown and remarks on necessary and sufficient conditions for solvability of the problem are also given.IntroductionAs is well known roof bolting has become the primary support system in almost all underground coal mines. But the ""theoretical"" design criteria for roof bolt patterns are rather problematic because: "" ... real mechanisms by which the roof bolts reinforce the immediate roof of underground coal mine entry are still relatively unknown"", see Peng (1986).The aim of this contribution is to present brief description of fundamentals of mathematical theory (see Hlavacek et al., 1988) which could be, according to our opinion and knowledge, very helpful for numerical modelling of a such type of problems. For the sake of brevity we restrict ourselves here to just one of the simplest possible problem: analysis of the behavior of interactive set composed by only single full - length - grouted bolt, resin (or cement) and suitable part of domain of a ""immediate"" neighborhood of bolt which should represent physical action of real rock material."

Dec 1, 1995

By Boyd Guthrie

Methods of distilling topped crude oils and distillates under vacuum, accompanied by good fractionation, have taken a place of major importance in the refining industry. In the refining of petroleum products it is generally desirable to produce a distillate of good quality, and this objective is attained by fractionation of a high degree. The laboratory and commercial practice have proved that by varying the amount of fractionation the quality of the distillate can be changed, and refiners are cognizant of the advantages of good fractionation. Distillation under high vacuum, however, is a relatively new practice in petroleum refining, and only during the last few years has there been an indication that this method may become a general practice in the industry. Vacuum distillation offers many advantages over older methods of distilling petroleum products. Vacuum combined with steam distillation, for example, is replacing straight-steam distillation because the quality of the products of vacuum and steam distillation surpasses that of those produced by straight-steam distillation. Although the injection of varying amounts of steam in a vacuum unit is common practice, the amount of steam used is becoming loss as the vacuum within the unit is increased. This report describes the construction of a visible-action laboratory batch still and fractionating column and gives certain data pertaining to the operation of the apparatus under vacuum for the production of lubricating distillates. The apparatus was designed and built to produce lubricating distillates under as nearly ideal conditions as possible, in order that a subsequent study of the characteristics of the distillates could be made. For example, a study could be made of the distillates obtained up to the point of cracking of the charge if a topped crude were charged to the still; if the still was used as a rerun unit for lubricating distillates a study of nearly the entire charge could be made. Only topped crude has been charged to the still so far, and therefore this paper is limited to the results obtained from the distillation of such a charge. The results so far obtained indicate that such an apparatus is valuable in a study of different crude petroleums as sources of lubricating distillates.

Jan 1, 1932

By Scott A. Stebbins

During 1981, the U.S. Bureau of Mines and U.S. Geological Survey conducted a mineral resource survey of the 6,400 acre (15,800 ha) Lincoln Creek RARE II area (No. 5983) in the Toiyabe National Forest (fig. 1). Samples of outcrops and stream channels contained no significant amounts of economic minerals. A radioactive deposit in a pegmatite dike occurs 1.25 mi (2.02 kin) southeast of the study area, hut similiar deposits have not been discovered within the area boundary. No coal or deposits were found.

Jan 1, 1982

By L. B. Pankratz

High-temperature heat contents were measured for two praseodymium oxides and three terbium oxides. There were: Pr2O3 (298° to 1,600° K), PrO1.833 (298° to 1,050° K), Tb2O3 (298° to 1,600° K), TbO1.719 (298° to 880° K), and TbO1.812 (298° to 850° K). With the exception of PrOl.833, all results were regular. PrO1.833 had a small thermal anomaly at 760° K with an extra absorption of 380 cal/mole. The measured heat content values, tabulated smooth heat contents, and entropy increments are reported. Heat content equations were derived.

Jan 1, 1966

By Ben A. Kornhauser

The mineral industry consisted primarily of natural gas production and of urea fertilizer, which was manufactured for domestic agriculture. Copper and iron deposits were being developed. Information regarding the mineral industry of Afghanistan was sparse. The Government continued to emphasize the development of mineral resources that could benefit the economy of the U.S.S.R. and repay Soviet grants. The northern half of the country, north of the Hindu Kush mountain range and adjacent to the U.S.S.R., received considerable Soviet aid to develop mineral resources.

Jan 1, 1986

By H. G. Iverson

The effects of adding boron and boron plus carbon to electrorefined vanadium were evaluated with respect to mechanical properties at low temperatures and response to heat treatment. Grain size was significantly decreased with the addition of 0.05 percent boron, the decreases ranging from 30 percent at 800° C to 75 percent at 1,100° C. Increasing the boron content resulted in only a small increase in strength at room temperature, but at 77° K, boron contents of 0.005 to 0.076 percent increased the yield strength of vanadium over 50 percent, from 70,000 psi to 110,000 psi. When boron and carbon were present together, the individual grain-refining effects obtained with either element were retained. Approximately a twofold increase in strength was obtained by age-hardening the alloys containing both boron and carbon. Alloys with only boron additions did not age-harden.

Jan 1, 1968

By James P. Bennett

The U.S. Bureau of Mines investigated the role of imported natural flake graphites in dolomite-carbon refractories used in steelmaking processes and evaluated carbon fibers as a potential substitute. Varying quantities (1.5-30 pct) of natural flake graphite and carbon fibers were added to test samples. The effect of the additions on modulus of rupture (75°-2,750° F), deformation under load (2,750° F), and air-slag-metal resistance (3,000° F) was studied. Carbon purity of natural flake graphite additions did not influence hot strength, deformation under load, or air-slag-metal resistance. When the quantity of 90-pct-carbon graphite addition varied between o and 30 wt pct, hot strength was highest, deformation under load lowest, and air-slag-metal wear the least at 10 wt pct. As test temperature increased from 500° to 2,750° F, the hot strength difference became less. Carbon fiber additions were limited to 1.5 pct in dolomite-carbon brick. At this level, physical properties were generally comparable to those obtained with natural flake graphite, but were below values obtained with 10-pet-f1ake graphite additions. Carbon fibers are not considered a satisfactory substitute for natural flake graphite.

Jan 1, 1989

By Gilbert M. Farrior

The electrical resistivity the coefficient of electrical resistivity the Hall coefficient, and the absolute thermoelectric power were determined in this Bureau of Mines investigation for nine compositions of the TiB2-CrB2 sub-system. The numerical values of the electrical resistivity and the thermo-electric power were greater for the intermediate compositions than for the end members. The absolute values of the Hall coefficients and the coefficients of electrical resistivity were less for the intermediate compositions than for the end members. The electrical resistivities and Hall coefficients were about the order of magnitude of most metals--from 34 to 202 microhm-cm and from about 0 to -23.3 X 10-4 cuP/coulomb. The thermoelectric power was somewhat greater than that of most metals--up to 15.6 microvolts per 0 C.

Jan 1, 1965

By Foster Fraas

A comparison has been made between cubes and spheres in the matrix of the high-intensity wet magnetic separator. For two inclined plane surfaces, such as may occur with cubes, the maximum force value, H [dH-dx] is at the point of nearest approach and is much higher than the force resulting from adjacent spheres. Although the maximum force value for cubes is higher, it decreases more rapidly at increasing distances. The maximum force for spheres is at an appreciable distance from the point of nearest approach. At field intensities for magnetic saturation of the iron spheres, the force extends to further distances with greater uniformity approximating that of the constant force or isodynamic field. The force is also independent of the sphere diameter, which permits the scaling of the sphere diameter to provide changes in particle migration distances without changes in force gradient.

Jan 1, 1972

By S. P. Holt

The Rush & Brown mine has been one of the most consistent small producers of copper ore in the history of Alaskan mining. Approximately 50,000 tons of ore have been shipped to smelters from the property. Production has been made from two distinct and separate ore bodies of dissimilar types. The Shear Vein deposit has been mined to a depth of 500 feet below the surface without a reduction in the size of the ore shoot or the grade of ore. The Magnetite ore body has been partly mined to a depth of 200 feet below the surface. Because of the favorable production record of the Rush & Brown mine, the present need for copper and the fact that the owners were attempting to place the mine in production, it was deemed advisable to investigate this property under the Strategic Minerals Act of 1939 as a possible source of copper.

Jan 1, 1948

By Denise A. Herzog

The U.S. Bureau of Mines conducted a study of cyanide leach technology used in Alaska's mineral industry from 1987 through 1990. Literature and cost data were obtained for mines in the contiguous United States, Canada, and Alaska that use cyanide to recover gold and silver. The data was compiled in an effort to evaluate the economics and conditions associated with cyanide use in Alaska. This report discusses heap leaching methodology and evaluates a "typical" heap leach operation in Nevada and compares the results of the Nevada operation to an analogous hypothetical mine in Interior Alaska. Five daily tonnage rates were analyzed for both the Nevada and the Alaska operations to evaluate the spectrum of economic possibilities. The discounted cash flow rate of return (DCFROR) for each production rate was then evaluated in terms of recoverable metal value (RMV). The Nevada RMV for each production rate was then compared with its Alaskan counterpart, and the results averaged. The Alaskan production costs are an average of 1.71 times greater than costs associated with mining in Nevada at a 0% DCFROR. At 15% DCFROR, costs in Alaska are 2.01 times greater than those in Nevada. Costs are higher in Alaska because of the shorter leaching season, increased labor and transportation costs, and heavier precipitation and vegetation.

Jan 1, 1991

By M. J. Ankeny

Coal-mine haulage ranks second as a cause of coal-mine fatalities, and the prevention of such accidents will materially improve progress in safety in the coal-mining industry. Beginning March 1950, Federal coal-mine inspectors were made responsible for completely investigating all fatal accidents in and around coal mines. During these 10 months, Federal coal-mine inspectors investigated 447 fatal accidents. This is a study of 121 of the fatal haulage accidents investigated, which constituted 27 percent of fatalities from all causes. Haulage employees represent only 12 to 15 percent of mine personnel, but, on the basis of accident frequency, their work is the most hazardous in coal mines. Fatal haulage accidents occurred in 53 bituminous coal-producing counties representing 14 States and Alaska. The physical conditions represent a cross section of' producing coal beds. Mining and transportation methods vary, from those of small hand-loading mines to those of modern mechanized mines.

Jan 1, 1951

By Robert L. Jones, Clifford Dunham

"INTRODUCTION The Wah Wah mine was examined 3/ by the Bureau of Mines in September, and a project was started in November 1942. Assistance was given by the Federal Geological Survey in formulating proposals and plans, and two geoloists were assigned to map the surface and underground workings in October 1942.HISTORYThe Pine Grove mining district was organized in 1S73, but no work was done there until it was reorganized in 1879, after which it is reported that a little ore was shipped. The Wah Wah Mining Co. was incorporated September 2, 1937. Prior to that time, predecessor organizations had spent approximately $122,000 on the property now held by this company. The board of directors of the Wah Wah Mining Co. approved expenditure of $47,652.14 from September 1937 to June 1942 for development. This work was confined to the Tasso shaft and connecting levels. Shipments in 1939 amounted to 925.789 dry tons with a gross value of $12,477.83. This ore contained 20,130 pounds lead, 1,390 pounds copper, 7,434 ounces silver, and 65.09 ounces gold. The mine was idle from July 1941 to November 1942, when, the Bureau initiated a project to unwater the Tasso shaft and proceed with the exploratory work as outlined in the War Minerals Report."

Apr 1, 1946

By W. W. Adams, V. E. Wrenn

"Production of explosives in the United States during the calendar year 1935 decreased 2 percent from 1934, according to reports covering all companies engaged in the manufacture of explosives during those years.Reports from manufacturers showed a total production of 308,381,250 pounds of explosives; this quantity included 39,170,016 pounds of permissible explosives 5/ 200,323,559 pounds of high explosives other than permissibles, and 68,887,675 pounds of black blasting powder of which 34,222,625 pounds were granular powder and 34,665,050 pounds pellet powder.Coal mines consumed 89 percent of the total production of blasting powder, 99 percent of the total output of permissible explosives, and 11 percent of the output of other high explosives.The metal mines of the United States used 28 percent of all high explosives other than permissloles, less than 1 percent of all permissibles, and 1 percent of all black powder produced.Quarries and nonmetallic-mineral mines consumed 17 percent of the high explosives other than pormissibles, less than 1 percent of the permissible., and 3 percent of the blasting powder.Construction work required the largest quantity, 40 percent of all high explosives manufactured during the year. Less than 1 percent of the permissibles and 6 percent of the black powder produced during 1935 was used in construction work."

Nov 1, 1936

Ten years ago we surveyed in "Uspekhi Khimii" the mechanism of the synthesis of hydrocarbons from CO and H2 (1).5 With new data obtained since then, mostly by Soviet researchers, our previous work (2), dealing with new forms and catalysts of the synthesis, is brought up to elate by reviewing research in this field. FORMATION OF CARBIDES The hypothesis that carbides are intermecliates in the synthesis assumes that carbon monoxide reacts with the metals of the eighth group and that this reaction is connected with the reversible reaction 2CO[=]C +CO2 (1) in a certain range of temperatures (3).

Jan 1, 1958

By George H. Schnakenberg

This Bureau of Mines publication describes a passive personal sampling device for N02 in air, developed by the New York University Medical Center under Bureau Grant G0133066. The sampler has been successfully demonstrated in the field and in the laboratory. In corroborative laboratory trials the agreement with reference method is excellent. The overall accuracy is approximately ±5 pct of reading to a precision of about ±l pct. All evidence indicates that these samplers should indicate the time-weighted-average N02 concentration to the above accuracy and precision equally well in the field since effects of wind velocity and relative humidity are negligible and the effects of temperature are about 0.1 pct per °F. The duration of exposure and the approximate temperature are the only data that need to be collected in the field. A two-step analysis procedure in field or service laboratory is then used to obtain the total cumulated exposure to N02 in parts per million-hours (ppm times hours), which can be converted to the time-weighted-average concentration of N02 in ppm by dividing cumulated exposure by the duration of the exposure.

Jan 1, 1976