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By R. D. Currie

Haulage accidents in the anthracite region cause fewer fatal and lost-time accidents per million man-hours than similar accidents in bituminous mines, a fact that may be accounted for in several ways, but primarily because haulage, in a large part of the region, is restricted to haulage crews operating only on the gangways where most of the miners seldom come in contact with movement or handling of cars and locomotives. Generally in underground mines the number of men injured compared with the number killed is greater for haulage than for roof-fall accidents, while the number of men killed by haulage is second only to the number killed by roof falls.

Jan 1, 1939

By James H. Cobbs

The purpose of this study is to investigate the application of boring equipment to the production of anthracite coal from steeply pitching beds. Both raise boring and augering equipment were considered. Previous studies (11) have indicated that boring equipment may have definite applications to the development of steeply pitching anthracite beds. This investigation was to carry forward previous work to determine the possible application of the two different types of equipment being considered. Previous conclusions have been substantiated by the results of this study.

Jan 1, 1975

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

By W. F. Marshall

This Bureau of Mines report discusses tests conducted with four different catalytic reactor designs to determine the influences of exhaust treatment systems on emissions from diesel engines. Although there was significant differences in oxidation efficiencies at light to intermediate engine loads, all four catalysts were very effective in reducing emissions at heavy loads. Compositional determinations included carbon monoxide, carbon dioxide, unburned hydrocarbons, oxides of nitrogen, aldehydes, sulfur dioxide, sulfates, and particulate loading. Particulate size, exhaust odor intensity, and the character of the unburned hydrocarbon component were also determined.

Jan 1, 1978

By W. D. Mcmillan

During the fall of 1943 the Bureau of Mines put down four churn-drill holes totaling 435 feet of bore at the McGregor zinc lead mine near Potosi, Washington County, Mo., after the property had been examined by John Soule, an engineer of the Bureau, in the fall of 1942. A small production of lead and barite ore had been maintained at this property for many Years from shallow deposits in residual clays. A few shafts had penetrated the underlying dolomites and exposed a network of narrow fractures containing galena, sphalerite, barite, and marcasite. The drilling by the Bureau tested conditions at depths ranging from 80 to 130 feet. This report sets forth the data resulting from the work.

Jan 1, 1948

By C. M. K. Boldt

The Bureau of Mines surveyed waste disposal sites at 18 metal and non-metal mines and conducted laboratory and full-scale field tests to de-termine the effects of tailings deposition techniques on physical properties of tailings pond beaches. Survey data included measurements of beach slopes, descriptions of deposition techniques, and measurements of beach physical properties taken at various distances from the point of discharge. Laboratory tests involved depositing two types of tailings, each with different grain-size distributions, into a settling trough and determining the resultant physical properties of settled materials along the length of the beach. Side confinement and the closeness of the water pool to the point of deposition caused the laboratory results to be inconclusive. Full-scale field deposition tests conducted at the tailings pond of a cooperating mine showed that there were similarities in relationships between exit velocities of tailings slurry and physical properties of the settled tailings on the beach.

Jan 1, 1988

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 A. Visnapuu

The Bureau of Mines has upgraded high-iron domestic chromite concentrates by a carbonyl process. The upgraded chromite concentrates show as much as 10 wt pct higher Cr203 content and up to a threefold in-crease in the Cr:Fe ratio, compared with the starting concentrates. The high-iron chromites were first reduced to convert the iron oxides to the metal, and then treated with CO at elevated pressures and low temperatures to convert part of the metallic iron fraction to iron pentacarbonyl. Carbonylation was accelerated by the addition of H2S in small quantities. The iron pentacarbonyl was extricated from the con-centrate in the pressure reactor during carbonylation by a CO sweep through a pressure-reducing valve and passed through a decomposer at atmospheric pressure to convert it back to iron metal and CO. CO pres-sure, temperature, promoter trends, and other factors enhancing iron pentacarbonyl formation are presented.

Jan 1, 1985

By F. S. Wartman

The presence of magnetite, either dissolved or suspended as solid crystals, in slags from the copper reverberatory furnace is a frequently mentioned cause of an abnormally high copper content in those slags. The presence of this oxide in the slag is to be expected, since it is present in appreciable amounts in both converter slag and roaster calcine which comprise a considerable proportion of the furnace feed. Magnetite is also a product of some of the furnace reactions. These abnormal losses result in several ways. Magnetite is supposed to favor the formation and retention of copper ferrite, in the slag. Crystals of solid magnetite suspended in the slag are objectionable-because they make the slag less fluid and often entrap globules of matte. Frequently these crystals settle into a layer at the slab-matte interface which may have such mechanical strength as to create a false bottom and interfere with furnace operation by preventing separation of matte from slag. Magnetite may, by crystallizing on the furnace bottom, build the bottom to such a level that the furnace can no longer be operated.

Jan 1, 1928

By Ivan F. Avery

OUTPUT of carbon black in 1959 increased in all producing States except New Mexico. The national increase was 20 percent. Domestic sales and exports increased 22 percent and 16 percent, respectively, resulting in a 21 percent gain in sales. Sales to the rubber industry, which purchased 95 percent of the domestic output of carbon black, increased 23 percent. Sales to all other major consumers also increased. Stocks decreased 82 million pounds during the year. [ ]

Jan 1, 1960

By J. D. Ramsdell

The study described in this report was undertaken to obtain information on the character and effect of antimony additions to titanium. The availability of high-purity, low-hardness titanium metal, resulting from fused-salt electrorefining techniques, permitted a reassessment and evaluation of the physical behavior of titanium-antimony alloys. Alloys, based on several grades of titanium containing up to 10 percent antimony, were arc-melted and processed to sheet by hot and cold rolling. Properties and characteristics were evaluated by hardness tests, hot and cold rollability, annealing treatments, metallographic examination, and tensile tests.

Jan 1, 1960

By C. Fang, D. B. Kittleson, K. L. Rubow

"Under contract to the U.S. Bureau of Mines, a study was conducted to investigate the feasibility of using the microorifice. uniform deposit impactor (MOUOI) to measure the size distribution of aerosols containing various mixtures of coal dust and diesel exhaust particles. The project objective was to determine if the mass concentration of diesel exhaust particles, in an airborne mixture of coal dust and diesel exhaust particles, could be determined on the basis of the size distribution of the two aerosols. In general, the mass of diesel exhaust particles is in the submicrometer size range while that of the coal particles lie in the larger size ranges.The MOUDI is a cascade impactor with small diameter nozzles to obtain small cut sizes and rotating impaction plates to avoid particle overloading of the deposit. For this study, a 7 stage version was used. At the sample flow rate of 30 L/min, the cut sizes were 0.10, 0.23, 0.70, 1.0, 2.6, 4.9 and 10 pm.Size distributions of aerosols generated in the laboratory and in several underground coal mines were measured. The primary emphasize of the laboratory tests was to ascertain if the diesel exhaust particles could be separated from the coal dust, regardless of mass fraction of the diesel exhaust particles in the total aerosol mixture. Diesel exhaust, from a Caterpillar Type 3304 NA diesel engine, was mixed with coal dust generated with a· TSI Model 3400 fluidized bed dust generator. Experiments showed the size distributions of the mixed aerosols exhibited two definite modes with the minimum between the two modes in the 0.7 to 1.0 um size range. Distinct modal separation was obtained as the mixture fraction of the diesel exhaust aerosols was varied from 3% to 98%.The field study was conducted in three underground coal mines, two utilizing diesel-powered equipment and the third exclusively using electric equipment. Sampling sites were selected to obtain a wide variety in the diesel exhaust and dust aerosol concentrations. Size distribution data showed these aerosols are bimodal. The mass median aerodynamic diameters of the diesel particulate mode and the coal dust mode were approximately 0.15 µm and 3 to 10 un, respectively. The results, in all cases, clearly show a separation between the two modes in the 0.7 to 1.0 µm size range with the minimum in the vicinity of 0.8 pm. The separation was found to be independent of mass fraction of the diesel exhaust particles, total particle concentration and sampling site."

Jan 1, 1989

By J. D. Ramsdell

The purpose of this investigation was to determine the effects of the impurities, oxygen, nitrogen, carbon, and iron (in low percentages) on the mechanical properties of electrolytic titanium. The strength and hardness of binary Ti-O, Ti-N, and Ti-C alloys are linear functions of alloy content in the composition range investigated. Compared to oxygen and carbon, nitro-gen is the most effective strengthener and hardener, followed by oxygen, then carbon. When the carbon concentration is above 0.10 percent, carbides are present, and strength and hardness are relatively unchanged. For equivalent hardness levels, Ti-Fe alloys are stronger than binary titanium alloys containing oxygen, nitrogen, or carbon. However, the strengthening is related to the presence of transformed beta in the structure.

Jan 1, 1960

By H. P. Greenwald

About mid-December 1936, the safety director of a large coal corporation visited the authors at the Bureau's Experimental coal mine to discuss a rock-dust barrier he had invented primarily for use in trackless entries of coal mines. The rock dust in this device was carried in its original paper containers and means were provided for ripping these open so that the dust might be scattered in the path of an explosion. The inventor termed the device a "bag barrier", and this term has been adopted in the present paper for convenience. At that time the device was in an early stage of development, and the inventor felt that the barrier should be tested to determine whether it had enough promise of being successful to justify further development. The matter was taken under consideration and finally three tests were made during the week of February 15, 1937. It was concluded that while the device did stop an explosion in two of the three tests, it was much loss effective than ordinary rock dusting, and that too few data were obtained to permit direct comparison with tests of other barriers. Apparently, the conditions under which the device could, be successful were somewhat limited, out the limits could not be defined without additional tests.

Jan 1, 1938

By Sam McNary

The U.S. Bureau of Mines used the East Fork Pine Creek watershed to conduct a pilot study for an inactive and abandoned mine lands inventory, during which techniques and methodologies would be developed for subsequent inventories. A total of 177 waste dump samples, 191 mill tailings samples, and 36 stream sediment samples were collected. Water samples were collected from 18 sample sites during five sampling events. Waste dump, tailings, and stream sediment samples were analyzed for antimony, arsenic, cadmium, copper, iron, lead, mercury, and zinc. Results indicate a multidisciplinary approach is necessary: disciplines should include geology, geostatistis, geochemistry, geophysics, biology, hydrology, and remote sensing; small prospects do not generally contribute to watershed contamination, major mine and mill sites may contribute metal enriched sediment of metal enriched water; speciation studies and bioavailability studies are important.

Jan 1, 1995

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 B. W. Gandrud

At the Southern Experiment Station of the Federal Bureau of Mines, reports are prepared from time to time on results of washability studies of commercially important coal beds in the Southern Appalachian region. The investigations that provide the material for these reports are made by the Bureau of Mines, United States Department of the Interior, in cooperation with the University of Alabama and the mine operators. This report records the results obtained on a sample of run-of-mine coal taken in June 1953 from the Pratt bed at the Davidson Coal Co. mine about 1 mile west of Graysville, Ala. One of the main objectives of a washability study is to obtain technically and commercially important data in connection with the best methods for preparing and utilizing the Nation's limited reserves of good coking coal. Such information is important from the standpoint of conservation in that it facilitates selection of preparation methods that will yield an acceptable grade of coking coal with a mini-mum of losses of coal in the rejects. The Pratt bed is one of the main sources of coking coal in the Jefferson County part of the Warrior field. This is the first time, however, that data from a complete washability study of coal have been obtained from this bed in Jefferson County. In the Graysville area, Pratt-bed coal has good coking characteristics and is used for blending with other coals in making metallurgical coal. The extent of its use in such blends is severely limited in this area, however, by the fact that it has a high sulfur content, which has not been reducible to any great extent by washery treatment.

Jan 1, 1955

By David C. Oyler

The U.S. Bureau of Mines studied the interaction of longwall shield supports and adjacent strata at the Meigs No. 31 Mine in southeastern Ohio. Twenty-three legs of twenty shields at midface were instrumented with pressure transducers and monitored for 11 weeks. During the project, leg setting pressures were reduced twice to determine the effect of setting pressure on shield-strata interaction. No correlation was observed between setting pressure and leg loading rates. The shield loading profiles were consistent with a model in which the roof consists of two zones, a thin immediate roof loading the shields well below the typical setting force and a main roof zone essentially supported by the coal and gob and loading shields through its convergence. This model was used to develop an equation for estimating average loading rates at the site. The only variable of the equation is time, and the equation consists of an exponential term to account for the immediate roof loading and a linear term to account for main roof loading. The equation gave good correlation with average loading rates, but the variation in loading from cycle to cycle was too great for the equation to give good predictions of individual cycle loading rates.

Jan 1, 2010

By A. W. Fahrenwald

Many factors enter into the efficient operation of the reciprocating type of gravity concentrator. Earlier investigators who studied these factor invariably used natural (crushed ore) products for their experiments, but in the present study synthetic products were used. The variables considered were (1) specific gravity of the sand grains, (2) size of sand drains, and (3) shape of sand grains comprising the table feeds. It is recognized, also, that the percentage relationship of the different kinds of grains is a factor affecting results. This factor is variable in one group of experiments but is thereafter kept constant.

Jan 1, 1929

By J. E. Chilton

The U.S. Bureau of Mines has developed an intrinsically safe carbon monoxide (CO) monitoring system for mines by coupling a fiber-optic data telemetry (FODT) system with a prototype electro-chemical CO monitor. The CO monitoring system can be used in a coal mine as one component of an early fire warning system. This system may be used in belt haulage entries when the entries are used for supplying ventilation air to working places. The FODT accepts a 0.1-to 1.1-V analog signal from the monitor and converts it to pulses (0 to 5 V) at frequencies from 1.1 to 11 kHz that drive a light-emitting diode (LED). An electrically nonconducting fiber-optic cable carries the LED signal to a remote receiver. The receiver analyzes the incoming light signal and displays the measured CO concentration in parts per million. This report discusses the performance of the FODT system and characteristics of the CO monitor such as response times, linearity, and temperature and pressure effects.

Jan 1, 2010