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By Zsuzsanna Zborovszky

[Certain chapters of the tentative document entitled, "Test Requirements for instruments & Apparatus to be Considered for MESA Intrinsically Safe Certification" are evaluated and supporting data are presented on certain key issues with the purpose of helping the regulatory agency in improving the above document. The subjects discussed in detail are: hot wire ignition with W and BeCu wires; the most sensitive methane-air :and propane air ratio; the ignition limits for inductive-resistive circuits in 8.3°; methane-air mixtures in the 24-OV, 100 mH-2 [ ]H range, the resistive ignition limit as a special case when L ? 0; the capacitive-resistive ignition limit representing a four ,dimensional problem is analyzed and discussed in general and the variation of the ignition limit using Vo and/or r2 as a parameter are determined experimentally. The ignition limit is also determined for the [r1 ,~ r2] = 0 case ("capacitor alone") and for the most dangerous capacitive resistive circuit combination. The ignition limits are below the limits proposed in the document. A survey of the different factors influencing the ignition is made as to their suitability to provide a constant safety factor. It is shown that a constant safety factor cannot be achieved. The best method for applying a safety factor appears to be the increase of initial pressure or use of other gas mixture. The revision of the safety factor concept and ignition limit curves is recommended.]

Jan 1, 1980

By Gary Choate

The work presented in this report represents the background activity which led to the fabrication and testing of a greenhorn and crowd limit switch system for electric shovels. The program began With a literature search and manufacturers product review to gather material as a basis for concept generation. Visits to three open pit mines provided information from operation and maintenance managers which was useful in preparing design concepts. These concepts were evaluated through laboratory tests and engineering analysis to select a final design concept. The resultant greenhorn is four separate shock absorbing pads each enclosed in a housing which bolts to the end of a dipper handle adaptor. The plungers impact against stops mounted to the saddle block. The crowd limit control is a nonmechanical device which senses the location of the dipper and makes appropriate commands to the crowd motor to insure against impacting the greenhorns. The electronic crowd limit control is redundant and indicates malfunction modes. The greenhorn prevents shovel damage in the unlikely event of impact.

Jan 1, 1983

By Damon C. Gray

This report contains a recommended program of acoustic research to be conducted by the U. S. Bureau of Mines. The program is directed toward the abatement and control of machinery noise in underground coal mining operations. The study conclusions and specific problem areas which led to the definition of the recommended program are also briefly described.

Jan 1, 1971

By Walter W. Kaufman

This report summarizes a study conducted to determine the state of the art of various rock removal systems and their capabilities. The objective of the study was to determine if currently manufactured equipment can adequately accomplish rock removal in surface mine reclamation applications. Evaluations of state reclamation regulations, with regard to topsoil rock content, were made to determine the rock removal requirements. The major categories of equipment studied are rock pickers and rock rakes. The impact of rock removal implementation on the reclamation operations is discussed in detail.

Jan 1, 1979

By J. W. Jensen

This report was prepared as a background reference for future publica¬tions concerning the damping capacity of metals and alloys. It contains a broad description of the theory and methods of measuring damping capacity and correlates the developments of the past decade in terminology, units, and techniques. Damping-capacity instrumentation at the Mississippi Valley Experiment Station, Rolla, Mo., is described. The bibliography contains over 150 references to recent articles, each tabulated as to material investigated and test variables, such as frequency, stress, mode of vibration, and temperature. INTRODUCTION After it discovered high-damping manganese-copper alloys before World War II, the Bureau of Mines began research on the damping capacity of alloys and has continued to expand this activity to the present time. In physical metallurgy, damping capacity has become an important research tool in the Bureau. The physical measurement of the damping properties of alloys was begun at the College Park laboratories, and later conducted at Salt Lake City under the direction of Dr. E. V. Potter. Among the many articles resulting from this work, Damping Capacity of Metals (108)3/ has received frequent men¬tion in more recent literature and describes briefly the methods of measurement employed at that time.

Jan 1, 1959

By Michael Rieber

An analysis of coal slurry pipelines was presented in our May 1976 study, Route Specific Cost Comparisons: Unit Trains, Coal Slurry Pipelines and Extra High Voltage Transmission (4]. The present study extends that analysis. The earlier work included technical and economic cost descriptions of the black Mesa and ETSI pipelines as well as some hypothetical pipeline routes. Water problems, safety and environment, required resources, and labor impacts were discussed at some length. Additionally, pipeline impacts on competing railroads, slurry-rail comparisons, and cost escalation. were analyzed. The difference in pipeline profitability to an owner-operator versus a promoter-builder was suggested. These aspects are not redone in this study. Here, we present a synopsis of the previous results and a general statement of coal slurry pipelines. Extensions of the arguments are presented where they appear warranted. New material is developed in the area of pipeline branching and tapping. This would appear necessary if slurry pipelines are to function as more than private lines; if they are, for example, to be responsive to common carrier requirements.

Jan 1, 1977

This publication summarizes, for potential contractors and other interested parties, the research, development, and demonstration contract projects programed by the Bureau of Mines for fiscal year 1979 (October 1, 1978-September 30, 1979) under its Mine Health and Safety Research program. The objective of these projects is to provide an ordered and sequenced series of advances toward the Bureau's overall goal of providing the system technology required to create a healthier and safer working environment for the Nation's miners.

Jan 1, 1979

By Howard W. Wainwright

This bibliography was compiled by the Bureau of Mines as part of an investigation into the possible utilization of low-temperature coal-tar bases. The bibliography consists of literature and patent references from about 1945 to 1961 and is divided into the following headings: Analysis and Composition; Production, Synthesis, Reactions, and Utilization; and Separation, Purification, and Properties. Although over 1,000 references are included, no attempt was made to insure a comprehensive survey. The literature and patent references are arranged alphabetically by author or patentee. When several publications have the same author they are listed in reverse order of age, with the newest first. An author index is included because secondary authors are not cross-indexed. In almost every instance, the entry is accompanied by a Chemical Abstracts reference for those interested in locating an abstract of the original paper.

Jan 1, 1962

By T. C. Woo

This report describes the program that studied the theoretical and practical aspects of the belt cleaning systems, investigated-the possibilities of a self-replacing and/or sell-adjusting belt cleaning device, and designed a horizonal pentagonal turret setup for the underground mine belt conveyors. This design resulted from comprehensive literature survey (both academic and commercial), actual mine visits, study of the mechanics of belt cleaning and bench-type experiments. It has complete working drawings and rough cost estimates.

Jan 1, 1977

By J. W. Adams

Two different techniques were wed to make measurements of the absolute value of electromagnetic noise in an operating hardrock mine, Grace Mine, located near Morgantown, Pennsylvania. Diesel-powered haulage equipment is used in this mine, and the electromagnetic noise environment it creates was measured to see how it differs from the environment created by electric-powered haulage equipment. One technique measures noise over the entire electromagnetic spectrum of interest for brief time periods. Data are recorded using broadband analog magnetic tape and are later transformed to give spectral plots. The other technique records noise amplitudes at several discrete frequencies for a sufficient amount of time to provide amplitude probability distributions. The specific measured results are given in a number of spectral plots and in amplitude probability distribution plots.

Jan 1, 1974

By Juh W. Chen

A process for recovery of energy from waste coal fines was investigated. The process, which was developed through laboratory, bench, and pilot plant scale experiments, consists of mechanical cleaning followed by high temperature oil agglomeration and pelletization. The process can produce a quality product under an economically and environmentally acceptable condition. Waste coal fines with ash less than 35: and HHV greater than 6,000 BTU/1b have been upgraded to a product with less than 15% ash and HHV Greater than 11,500 BTU/lb. A computer model has been developed to optimize the processing costs and to perform economic evaluation of specific sites. Ultimately tine model can be utilized to establish a priority listing for a region in assisting the determination of reclamation strategy.

Jan 1, 1983

By Larry A. Haas

Carbonyl sulfide (COS) was decomposed to sulfur and CO in a silent electrical discharge. A threshold of about 4 kv at 60 Hz was required to dissociate the gas in a laboratory ozonizer at 790 torr with electrode gaps between 1 and 5.5 mm. Above the threshold value, the reaction rate increased with increasing voltage with helium or nitrogen diluent. With the latter diluent, higher voltages had to be applied to obtain the same yield in the 4-to 12-kv range. The COS decomposition rate increased with COS concentration, but a saturation value was reached at about 10 pct COS. The reaction rate decreased at low linear gas velocities as obtained at lower gas flows, larger electrode gaps, or larger reactor volumes. Increasing gas temperature also decreased the decomposition rate. The presence of solid adsorbents such as quartz wool, bauxite, or charcoal had no significant effect on the reaction rate. The addition of S02 did not affect the COS decomposition rate, but small amounts of water decreased the reaction rate. Over 50 pct of the COS was decomposed at room temperature and atmospheric pressure in a l7-kv ozonizer using a gas containing 0.9 pct COS in helium flowing at a rate of 0.3 liter/min. The average current was less than 5 ma. This method has possible application in eliminating the toxic air pollutant, COS, which is generated in petroleum refineries and in processes involving reactions between sulfurous and carbonaceous materials. Carbon monoxide that is formed can be further oxidized to CO2 after the collection of elemental sulfur.

Jan 1, 1972

By John P. Hansen

Batches of red or brown iron ore concentrates, weighing 100 or 200 grams, were reduced with gaseous reductants in a laboratory-sized fluidized-bed reactor. Using a loss of weight technique, the rates of reduction were measured and the effects of temperature, gas consumption, and gas flow rates were determined. Below about 725° C the rate of reduction was controlled by the chemical reaction at the reduction interface having an activation energy of about 10 kcal/g mole. Above about 725° C the rate of reduction appeared to be controlled by the flow of the gaseous reductant and therefore to be directly proportional to the flow rate. Above 725° C, hydrogen reduced the iron ore much faster than carbon monoxide. In gas mixtures, carbon monoxide or nitrogen reduced the hydrogen partial pressure and lowered the reaction rate proportionally. When present in large concentrations, carbon monoxide had a serious inhibiting effect on the reduction rate, probably owing to carburization and sintering of the reduced iron.

Jan 1, 1970

By Philip W. Holland

This Bureau of Mines report discusses the results of three independent reconnaissance geochemical surveys conducted in the vicinity of the Bush Dome reservoir in the Bureau-owned Cliffside field near Amarillo, Tex. The surveys consisted of (1) determining the helium content of area ground waters, (2) determining the helium content of area soil gases and ground waters, and (3) determining the helium content of soil gases collected on a grid sampling pat- tern in the Cliffside field area. The native natural gas in the Cliffside field contains about 1.8 percent helium. To date, approximately 54 billion cubic feet of gas containing approximately 39 billion cubic feet of helium has been injected into the center of the Bush Dome structure. The research work, which was completed under contracts, was done to determine if helium concentration levels in ground water and soil gas could he used as an indication of the presence of helium in a subsurface natural gas accumulation. Results of the surveys were positive in that helium-in-water and helium-in- soil-gas anomalies were detected in portions of the Cliffside field area. All helium analyses were performed by mass spectrometric techniques.

Jan 1, 1979

The purpose of this report is to describe the work accomplished by Mine Safety Appliances Company under Contract No. H0110845. This contract required the design, installation and testing of a permissible mine surveillance and communication system for the USBM Bruceton experimental mine facility. While much of the design and operational detail of this system can be drawn from the instruction manuals delivered with the equipment, some of it will be repeated here in Volume I for the sake of clarity, but the principal objective will be to report on overall system and subsystem performance and to suggest design alternatives for future consideration. Details of the overall system design will be found in Volume II of this report.

Jan 1, 1973

By R. L. King

This report describes a method for designing and constructing ground beds that has been developed under the sponsorship of the Bureau of Mines. The procedures for designing and constructing a driven-rod ground bed with a resistance of 5 ohms or less are given. Some of the theory of soil resistivity and fall-of-potential resistance measurements is included. Results of a bed constructed at the Bureau of Mines mine car roadway are presented.

Jan 1, 1978

By L. W. Higley

It is estimated that well over 20 million lb of chromium and 8 million lb of nickel, plus other metal values, are diverted annually to furnace dusts, mill scale, and contaminated swarfs in the domestic stainless and other specialty steelmaking industry. Little inroad has been made toward the in-plant recycling of these wastes to reclaim the metal values. The Bureau of Mines has devised a process for recovering about 90 pct of the chromium and molybdenum and well over 90 pct of the nickel and iron from stainless steelmaking furnace dusts, swarf, and mill scale. Other metals such as manganese are also recovered. Initial laboratory results were confirmed and expanded to include a wide variation of stainless steelmaking waste mixtures. Later experiments have included specialty steelmaking wastes other than from stainless steelmaking. Significantly, the ease of technology transfer has been demonstrated by a number of industrial-sized (19-ton) commercial electric furnace heats, in which the pelletized wastes represented some 10 to 20 pct of the furnace charge, replacing part of the normal scrap charge. Results of these successful large-scale trials are presented. Some information is also presented on incorporation into the pellets of chromium-bearing particulate wastes originating from other than steelmaking production. Cost evaluation indicates the process is economically attractive.

Jan 1, 1982

By W. L. Falke

The Bureau of Mines has developed a system that permits the "soft" soldering of aluminum and aluminum alloys with standard tin-lead solders. The method employs application of a thin nickel-copper-alloy coating to the substrate, which enables the tin-lead solders to wet readily and spread over the areas to be joined. With conventional technology, aluminum and aluminum alloys are extremely difficult to solder because tenacious surface oxide films prevent wetting. With the Bureau-developed method, the aluminum substrate is mechanically or chemically cleaned to facilitate bonding to a minute layer of zinc that is subsequently applied with an electroless zincate solution. The nickel-copper-alloy (30 to 70 pct Ni) coating is then applied electrolytically over the zinc, using immersion cell or brush-coating techniques. Development of acetate electrolytes has permitted deposition of the proper alloy coatings. The coated areas can then be readily joined with conventional tin-lead solders and fluxes. The joints so formed are ductile, strong, and relatively corrosion resistant, and exhibit strengths equivalent to those formed on copper and brass when the same solders and fluxes are used. The method has also been employed to soft-solder magnesium alloys.

Jan 1, 1983

By M. M. Gilkey

Pegmatites in Colorado occur for 150 miles along the Front Range (eastern-most range of the Rocky Mountains) from Larimer County on the north to Canon City on the south, and west into the Gunnison area. Many of the deposits have been classified. Minerals found in the various dikes include beryl, scrap and possibly punch mica, lithium-bearing minerals, columbite-tantalite, feldspar, and several rare minerals. Pegmatites are abundant in the Crystal Mountain district in Larimer County. About 5 miles south of the Crystal Mountain district and often identified with that district is the Hyatt pegmatite area. The Hyatt Ranch deposit has attracted particular attention because of the comparatively high beryl con-tent of the upper part exposed in opencut workings.

Jan 1, 1960

By D. Hoffmann, S. Plumb

IRUP is an iron-rich ultramafic pegmatite rock that formed due to hot ironrich fluids and gases replacing local stratigraphic zones of the Bushveld Complex. This study focuses on the estimation of the probability of IRUP occurrence on the Merensky Reef at the Marikana Karee Mine. A 2.15 million centare IRUP-rich domain at the Karee Mine was initially defined from the interpretation of a surface aeromagnetic anomaly, and exposures in the mine workings. Surface boreholes (spaced 250-500 m apart) within this IRUP domain contain approximately equal numbers of IRUP-replaced and IRUP-free intersections. Owing to the uncertainty in the continuity of the IRUP alteration (a result of the wide borehole spacing), the risk associated with the development of mining infrastructure within this domain is unquantifiable. Semi-quantitative data comprising visual estimates of IRUP replacement from reef development mapping data and surface borehole reef intersections was interpolated into blocks using indicator kriging estimation. Comparative analyses of the estimate of IRUP occurrences were made by changing the block size and declustering the data systematically. Reconciliations of the probability of IRUP predicted from the block models derived from the different data-sets and sequential indicator simulation models were analysed for four mining study blocks. A quantitative approach to modelling the occurrence of IRUP can be an additional tool for refining the estimate of the geological losses that inform the mine plan in such high-risk zones.

Jan 1, 2015