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By H. S. Chiang, Y. Luo, S. S. Peng

"IntroductionThe way in which the particle sizes distribute in the airborne coal dust plays an important role in the transportation of the dust in the mine air and human respiratory systems. Though the particles of a size less than 10 microns could be inhaled, the real distractive portion of the dust is that the sizes range from 1 to 5 microns since only they can reach the lungs and be retained there. Those with an equivalent diameter larger than 5 microns will settle on the membranes of the branchial tubes(1) while those with diameter less than 1 micron can either be exhaled out of the lungs or the settled quantity is so insignificant that does very little harm to the lungs. In the transportation process, the finer dust will fly farther away from the sources than the coarser ones. Thus once the fine dust is generated and becomes airborne, it will spread out to a larger area.In this paper, the coal samples collected from two longwall faces were analyzed statistically for size distribu¬tion. A mathematical model is proposed and the effects of different conditions on the dust size distribution were analyzed using the mathematical model.Sampling and Statistical AnalysesSampling Instrument and ProcedureThe instrument used in the sampling were Mine Safety Appliance (MSA) personal sampling units equipped with 10-mm nylon cyclones, pre-weighed MSA PVC filters and constant-flow pumps.Two longwall operating faces were selected for the dust sampling. The two faces were located in two coal mines ex-tracting Pittsburgh seam. The double-ended ranging-drum shearer applying the unidirectional cutting sequence was employed. The two-leg shield supports were used for face support. The width of the two faces was about 215 meters.In each of the two faces, four sampling stations were set up. The stations were located at the cross-cut immediately outby the headentry side, the 15th support (25 m), 65th support (107 m) and 111th support (182 m) from headentry T-junction, and numbered as #1, #2, #3, and #4 station, respectively (Figure 1). At each sampling station, a group of three sampling units was hung at proper position. At cross¬cut (#1) station, the units were hung about one foot under the roofline in the center of the cut (Figure 2a), and at the stations in the face, the units were position near the hydraulic legs and one foot below the support canopy (Figure 2b).One complete set of 12 samples was collected for each day. The sampling were performed for five consecutive days. All the samplings were conducted in the morning shifts. The time duration of the sampling for each day was about five hours. During that time, the shearer might complete 5 to 7 mining cycles."

Mar 1, 1989

By H. C. Hamontre

The liquid-level gage described in this report is an instrument designed to locate liquid levels in wells rapidly and accurately and, with auxiliary equipment described, to follow moving liquid levels automatically. The depth at which the instrument makes contact with the liquid in a well is indicated at the surface by a depth meter on the cable to which the instrument is attached. When the gage is used to follow a surging moving level, the liquid depth is indicated continuously at the surface. This report contains a description and illustrations of the gage and outlines the operating procedures. The instrument is 1-3/4 inches in diameter and approximately 6 feet in length and may be operated through 2-inch tubing. The gage consists essentially of a float that moves upward with respect to the rest of the assembly, causing a change in the flow of electric current from the surface when the liquid level is reached. The instrument has been tested under a variety of conditions and has been found to be sensitive to changes in liquid level of 1/2 inch. Its accuracy is limited principally by the accuracy of the wire-line depth indicator used. It is not affected by pressure or temperature, and it can be run in open hole or under pressure through a lubricator. It employs only one electric circuit and can be run on an Amergraph single-conductor cable (type 1-H-0) ,

Jan 1, 1954

By K. K. Kelley, W. W. Weller

The heat capacities of four crystalline silicates of barium ( BaSiO3 , BaSiO4 , Ba Si¸0 , and BaSi₂0 ) and two crystalline silicates of strontium (SrSio and Sr₂Sio ) were measured over the temperature range from 51 ° to 298° K. The results were used to evaluate the entropies at 298.15 ° K. The entropy values were joined with known heats of formation to obtain the free energies of formation of the silicates with respect to their constituent oxides at 298.15 ° K.

Jan 1, 1964

By J. A. Eisele, D. J. Bauer, D. E. Shanks

As part of its effort to produce cell - grade alumina from clay , the Bureau of Mines investigated the hydrogen chloride gas - sparging crystallization of aluminum chloride hexahydrate ( ACH ) from aluminum chloride liquor , to provide information for optimizing the crystallization operation . Four parameters important in controlling the crystallization of the aluminum chloride hexahydrate and the concentration of impurities , particularly phosphorus and magnesium , in ACH crystals are ( 1 ) aluminum chloride concentration in the feed solution to crystallization , ( 2 ) hydrogen chloride gas flow rate , ( 3 ) temperature , and ( 4 ) concentration of phosphorus and magnesium also in the feed solution . Parameters 1 , 2 , and 3 affect crystal formation . The combined effects are very important because the phosphorus and magnesium concentrate in the crystals during the early stages of crystal growth . Aluminum chloride hexahydrate of cell -grade purity was crystallized from saturated aluminum chloride solutions containing less than 0.003 wt - pct P205 and 0.010 wt - pct Mg0 . Crystallization temperatures less than 60° C decreased crystal purity .

Jan 1, 1965

By Richard F. Link

The principal procedures for the statistical analysis of gold assay and other trace-element data depend on applying either the normal frequency distribution or the lognormal frequency distribution. The consequences of applying both methods are examined through reference to example data from United States and South African gold mines. It is concluded that for estimation of average grades, except for certain data with a very high coefficient of variation (ratio of standard deviation to mean), use of the lognormal distribution is ordinarily undesirable because bias may be introduced and little efficiency can be gained. However, if biased average grades can be tolerated, as in the examination of data from surveys in exploration geochemistry, use of the log-normal distribution may be desirable. Various statistical analyses are detailed, and the tables presented to implement the analyses are more complete than those previously published.

Jan 1, 1971

By M. D. Carver

The purpose of this investigation was to determine the effects of variations in content (near the residual level) of the impurities aluminum, nitrogen, manganese, and copper on the corrosion rate in pressurized hot water and in pressurized steam of zircaloy-3, a zirconium-base alloy of 0.25 percent tin and 0.25 percent iron. Thirty-five 10-pound ingots were cast with the appropriate additions of impurity elements, and these were converted to wrought sheets. These specimens were then tested both in water and in steam. The analysis of the resulting data showed that in environments of either pressurized hot water or superheated steam, corrosion rates increased with increasing content of aluminum, nitrogen, or manganese, but were not affected by variations of copper. The effects of aluminum and nitrogen were found to be greater than the effect of manganese. INTRODUCTION At the request of the Atomic Energy Commission (AEC) in August 1956, the Federal Bureau of Mines, in cooperation with Bettis Plant of Westinghouse Electric Corp., began investigating the effects of certain impurity elements on the corrosion rates of zircaloy-3 in pressurized hot water and in pressurized steam. It was necessary to know these effects in order to set control limits on residual impurity levels in zirnaloy-3, intended for heat transfer service in the nuclear reactor of the pressurized water type. A factorial expert it was designed by Westinghouse statisticians. The Atomic Energy Commission provided raw zirconium sponge purchased from Wah Chang Corp. The Bureau's laboratory at Albany, Oreg., made material of different combinations of impurity levels and subjected the material to corrosion tests. This report will describe the work done at the Bureau laboratory and will show, quantitatively the effects of different residual levels of aluminum or nitrogen, or manganese or copper on corrosion rates.

Jan 1, 1961

By M. M. Hassan

This report describes the analysis tools developed at West Virginia University which can be implemented to optimally design coal mine electrical systems. The basic analytical tools for all power systems are the load-flow and short-circuit analysis. Well known programs have been developed for analysis of ac transmission and distribution systems, but they are not applicable to a system which has combined ac/dc distribution, such as a coal mine power system. Furthermore, the topology of a coal mine electrcal system changes continuously due to the movement of the locomotives on the track. In the first section of this report, algorithms for carrying out load flow and short-circuit analysis of a coal mine electrical system are described. Results from the study of a typical coal mine system are presented. In the second section a method is described to optimally size power cables for cyclic loads. The method is based on the development of a thermal-electric model for a low-voltage power cable. Results from experimental verification of the model are also presented. These techniques are useful in the safe, efficient, reliable and economical design of the coal mine electrical power systems.

Jan 1, 1979

By S. J. Pearce

The Bureau of Mines has prepared, as circumstances have dictated, a series of schedules setting forth the minimum requirements that various types of equipment should meet to be considered safe and satisfactory for use under certain hazardous or unhealthful conditions. These schedules cover a wide variety of devices ranging from explosives to electrically operated mine locomotives. This paper discusses the functions and operations of schedules under which respiratory protective devices are tested and approved. It emphasizes that the aim of the Bureau respirator-approval system is to make available to the public respirators that meet definite performance requirements. The responsibility of the respirator manufacturer in pre-testing the device and in maintaining its quality after it is approved are explained. Aid is provided for the user in selecting the proper device for specific application, and a plea is made for better education of all concerned in the proper use of the devices. DISCUSSION Provisions have been made for testing and approving the following types of respiratory protective devices: Self-contained breathing apparatus,2/ supplied-air respirators,3/ gas masks,4/ dispersoid respirators,5/ and chemical-cartridge respirators.6/ These devices are tested at the Central Experiment Station of the Bureau of Mines in Pittsburgh, Pa. Self-contained breathing apparatus is tested by personnel of Health and Safety District B; other types of respirators are tested by the Branch of Health Research.

Jan 1, 1957

By D. Montagna

The Kroll-Betterton process for debismuthizing lead is based on adding calcium and magnesium to impure molten bullion to form solid Ca-Mg-Bi inter-metallic compounds that float on the surface as drosses. Present practice in industry is to hand-skim off these drosses, often followed by hydraulic pressing to squeeze out some of the entrapped liquid lead. In an effort to develop an improved technique, the use of an argon-shrouded dipping centrifuge to perform the required phase separation was investigated. Centrifugation experiments demonstrated that the bismuth content of an impure bullion could be lowered from an initial 0.5 percent down to 0.03 percent with a lead recovery of 90 percent, which is comparable to lead recovery after hand skimming of drosses in commercial lead-debismuthizing operations. Centrifugation provides better control in removing drosses, faster operation with less oxidation and relatively little fuming, and recovery of a lead bullion that approaches commercial specifications.

Jan 1, 1972

By Anthony W. Sparks

The Bureau of Mines conducted tests designed to compare its breathing metabolic simulator (BMS) with other methods that are currently used to evaluate the performance of respiratory protective equipment. The BMS is a commercially developed device that uses a piston cylinder to simulate breath movement. Using a propane furnace that consumes oxygen and forms CO2, the BMS also simulates the respiratory metabolism of humans. The breathing and metabolic subsystems of the BMS are described in detail in this report. Results are compared from tests that used the BMS to evaluate respiratory equipment and from tests that used human subjects for the same purpose. The BMS was also tested against a pulsatile breathing machine (PBM) previously designed by the Bureau. Both machines were used to test respiratory equipment, and the test results are compared in this report. To illustrate typical applications of the BMS, the report briefly describes how the BMS was used to test two different types of closed-circuit respiratory apparatus, and the test results are presented. This research showed that BMS test results compared more closely to the results of tests that used human subjects than did results obtained using the PBM.

Jan 1, 1980

By D. N. Nilsen

The Bureau of Mines is investigating a method to recover Ni, Cu, and Co from low-grade domestic laterites through reduction roasting, leaching, sol-vent extraction, and electrowinning unit operations. The objective of this research is to develop processing technology that can convert low-grade domestic deposits containing critical metals into national reserves. As a part of this research, a solvent extraction system was investigated for the extraction of nickel and copper, followed by the separation and production of suitable electrolytes. Nickel and copper were coextracted from ammoniacal ammonium sulfate leach liquors (pH~9.5) with LIX 64N extractant in a laboratory-size mixer-settler continuous circuit. Three extraction stages resulted in >99-pct extraction of nickel, substantial copper extraction, and essentially no cobalt extraction from leach liquors. A crowd stage reduced the ammonia loading on the solvent by maximizing nickel loading. Residual ammonia was removed from the loaded solvent with a pH-controlled scrub. Nickel and copper loaded on the solvent were separated by selective stripping. Typical nickel strip circuit operation using electrolyte containing 90 grams per liter (g/l) Ni and 11.9 g/l H2S04 yielded >99.9 pct Ni stripped from the solvent in five stages. The copper loading on the recycled solvent was controlled in a copper strip stage using electrolyte containing 25 g/l Cu and 160 g/l H2S04,

Jan 1, 1981

By C. W. Davis

This is the first of a series of papers being; prepared as the work progresses in a study of the hydrometallurgy of manganese. The investigation is being made in an endeavor to make possible the utilization of lour-grade domestic manganese ores. The value of a hydrometallurgical process for manganese depends on the present and future uses for manganese products.

Jan 1, 1930

By B. R. Eichbaum

To develop technology to assure an ample supply of zinc and to reduce environmental pollution, the U.S. Bureau of Mines investigated alternatives to the roast-leach process for treating complex sulfide concentrates. Previous studies proved that low-grade zinc sulfide (ZnS) concentrates could be leached using chlorine-oxygen to produce zinc chloride (ZnCI2). The process involves high energy requirements for evaporating the pregnant solution to produce anhydrous ZnCl2 needed for electrolytic cell feed. An efficient hydrometallurgical process would facilitate treatment of lower grade ores than can be used in conventional processing and would render roasting unnecessary. An alternative method was devised for recovering ZnCl2 from solution. Zinc diammine chloride [Zn(NH3)2CI2] was precipitated from solution by adding ammonium chloride (NH4CI) and sparging with ammonia (NH3) to a pH of 6 to 7.5. The spent solution was treated with calcium hydroxide [Ca(OH)21 at 60° to 80° C for 1 to 4 h to remove remaining zinc and NH3. The Zn(NH3)2CI2 was heated to 300° to 400° C to remove NH3 and produce anhydrous ZnCI2. A possible flowsheet was devised and is included.

Jan 1, 1991

By Jack R. Woodyard

Scientists at the U.S. Bureau of Mines are studying iron aluminides as possible substitutes for stainless steels to reduce the Nation's dependence on imported strategic and critical materials. In a Bureau investigation on the mechanical properties of Fe-28Al, it was found that the material's machining properties were significantly improved at slow tool and feed speeds. Machining techniques normally used for brittle materials failed or were costly. Further experiments using a 5-in (12.7-cm) mill cutter with carbide inserts, operating dry at minimum machining speeds, produced visually smooth sample surfaces with no tool damage. As a result of these experiments and a review of published data on hydrogen embrittlement of iron aluminide under tension, non-water-based (e.g., sulfur-based) lubricants were chosen for production machining. Four-flute, 3/4-in (19-mm) carbide end mills were used at slow speed under lubrication. This latter procedure reduced tool wear and breakage by a factor of 2. Machined surfaces and specimen cross sections were analyzed by scanning electron microscopy to detect microcracking. Tensile tests gave the expected yield and ultimate strengths, indicating that no degradation by low-speed machining occurred. This study extends this work to show that the alloy can be machined at higher speeds using high-speed steel end mills, and that water-soluble cutting oil is a suitable lubricant and coolant.

Jan 1, 2010

By W. H. Ode, W. A. Selvig

Briefly, this swelling test consists in heating 1 gram of pulverized coal in a silica crucible over a gas flame under prescribed conditions to form a coke button which is compared in size and shape with a series of standard profiles numbered 1 to 9. These profiles are intended to cover the size and shape of buttons obtained from coals covering a wide range in plastic properties. The number of the standard profile with which the maximum cross-sectional area of the button most nearly corresponds is recorded as the swelling index. Although the swelling test showed poor relationships with the various tests that were used for measuring expansion or contraction of coal during carbonization, it gave indications of having value in measuring free-swelling and coking properties of coals when burned on fuel tests. An opportunity to investigate this occurred when an engineering company reported pronounced differences in burning characteristics on grates of various shipments of Pocahontas coal. Some of these coals gave trouble by swelling excessively and clogging the grate. Samples were obtained, and it was found that the troublesome coals gave radically higher free-swelling numbers than did the coals that performed satisfactorily. Also, it was found that the free-swelling index test gave better differentiation between coals than could be obtained from the coke buttons from the standard volatile-matter test or iron agglutination-value results. The results of the free-swelling test were confirmed by the Subcommittee on Plasticity and Swelling, Coal, a special group of the Subcommittee, under the chairmanship of R.A. Shuman, worked along with the test method. Estberg, Limacher, and Shuman of the Battelle Memorial Institute investigated the various factors affecting the test and found that the swelling index was a good indication of the suitability of coal for performance on residential-type stokers from the swelling characteristics of the coal. Data were presented that also showed that the index was helpful in the selection of coal for industrial underfeed stokers.

Feb 1, 1948

By J. J. Pfeiffer, J. W. Myers, A. A. Orning

A study was made of the feasibility of using washery refuse in the manufacture of lightweight aggregate for building materials . Preliminary caking and burning tests showed that the refuse could be converted into lightweight aggregate but that refuse passing a No. 14 U.S. Standard screen could not be used without additional processing . The aggregate was prepared by pelletizing the refuse and burning out the carbonaceous material on a chain- grate in a refractory - lined furnace . A small stationary - grate furnace was used to study the process variables involved and establish optimum ignition and combustion conditions . Maximum ignition rates were obtained at air rates of approximately 200 lb per sq ft hr , but air rates of 450 or higher were required in the burnout period to obtain temperatures high enough to sinter the ash . The data obtained from this unit were used as a guide in the operation of the chain- grate furnace . In the chain - grate furnace , satisfactory results were obtained by using primary air rates of 200 lb per sq ft hr in the ignition zone and 500 lb per sq ft hr in the burnout zone . The ignition- zone air was preheated to 500 ° F , but the air for burnout was not preheated . A total of 2-1/2 tons of aggregate was prepared in this unit and made into experimental block . A commercial development based upon the results of this study yielded a product which met the ASTM specifications C 130-42 for lightweight aggregate , and blocks made from the aggregate were of good color , durable , and light - inweight .

Jan 1, 1964

1. In 2002, a total of 763 nonmetal mining operations reported employment to the Mine Safety and Health Administration (MSHA). Examples of nonmetal mining operations include the mining of clay, trona, barite, phosphate rock, gypsum, talc, gemstones, and pumice. Nonmetal mines comprised 5.3% of all mining operations. • Nonmetal mining operations are located in all but nine states or territories (Alaska, Delaware, Maine, New Hampshire, Rhode Island, Vermont, Wisconsin, Puerto Rico, and the Virgin Islands). • Mines producing common clay comprised 29.2% (n = 223) of all nonmetal mining operations.

Jan 1, 2004

By Guy E. Dent, Hugo E. Kuehn

"SUMMARYFor making a comparison of magnetic surveys measured from the ground and from the air, Worcester County, Maryland, was chosen as a proving ground. Vertical magnetic intensities were observed on the ground, and total magnetic intensities were observed from the air. A comparison of the two magnetic maps reveals similar large magnetic features, but these are displaced in some instances by distances greater than a mile. Magnetic terrane in the two charts is of the same type but often differs greatly in respective characteristic features.The sacrifices in accuracy that may be expected from the use of different systems of diurnal magnetic corrections on ground observations constitute a part of this report.INTRODUCTIONThe value of magnetic surveys for gaining information concerning the crystalline basement is recognized increasingly. That this topography is often reflected to a major degree in the overlying sediments with certain offsetting is well understood. Even where such sediments are deep, the surface topography of upper formations often reflects this bedrock topography to a certain degree."

May 1, 1947

By Jacqueline A. McClaskey

The U.S. Bureau of Mines (USBM) Information and Analysis Directorate collects worldwide data on virtually every commercially important non fuel mineral commodity. These data form the base for tracking and assessing the health of the minerals sector of the U.S. economy. The USBM's data collection activity was instituted by the 47th Congress in an appropriations act of August 7, 1882 (22 Stat. 329), which placed the collection of mineral statistics on an annual basis. The most recent authority for the USBM survey activity is the National Materials and Minerals Policy, Research and Development Act of 1980 (Public Law 96-479, 96th Congress). This act strengthens protection for proprietary data provided to the U.S. Department of the Interior by persons or firms engaged in any phase of mineral or mineral-material production or consumption.

Jan 1, 1993

By B. H. Eccleston

Experimental data were obtained from two medium-duty diesel engines derated to qualify for use in underground mines. Gaseous and particulate emissions from these engines were measured and results provide information on the effect of exhaust treatment devices on the emissions. The devices in the study were a catalyst, a particulate trap, and an exhaust gas cooler of the water scrubber type. Emission levels of carbon monoxide and hydrocarbons were observed to be very low in comparison with emission levels of comparable engines in full-rated operation. Oxides of nitrogen and benzo(a)pyrene content of the exhaust also were found to be somewhat low in comparison with previous findings. For particulate reduction, the combination of a particulate trap and a scrubber was observed to be the most effective combination tried; in some cases, over 60 pct particulate reduction was effected by the trap-scrubber combination.

Jan 1, 1981