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By K. D. Plants, J. H. Holden, L. F. Willmott

Pulverized high- volatile A bituminous coal was gasified with oxygen and superheated steam in a pressure - gasification pilot plant equipped for steampickup feeding . The pilot plant operated satisfactorily at relatively high steam- to - coal ratios , but steam- to - coal ratios could not be reduced much below 0.5 lb / lb without condensation of steam or softening of the coal . Carbon gasified , gas composition , and coal and oxygen requirements were essentially the same as for a pilot plant equipped with a fluidized coal feeder . Average results from the pilot plant equipped for steam- pickup feeding were coal requirement , 37.3 lb/M ( 1,000 ) scf of CO + H₂ produced ; oxygen requirement , 358 scf /M scf CO + H₂ produced ; and carbon gasified , 87.7 percent .

Jan 1, 1964

By W. E. Wallace, P. S. Mike, C. A. Hill, V. Vallyathan, M. J. Keane

Respirable quartz duet and a kaolin clay dust have been found to be of comparable cytotoxic potential in vitro on a specific surface area basis (Wallace, et a1,1985), despite the distinctly different potentials of quartz and clay for causing pneumoconiosis or pulmonary fibrosis (Sheers, 1984). A respired particle depositing in a respiratory bronchiole or alveolus will contact a pulmonary surfactant hypophase, of which a primary component is diacyl glycerophosphorylcholine, or diacyl lecithin (DPL) (Clements, et al, 1970). Several studies have found that adsorption of such surfactant suppresses in vitro cytotoxic effects of quartz dust (Marks, 1957). Subsequent phagocytosis and digestion by a macrophage may remove the coating, restoring cytotoxic potential and initiating disease processes (Iles, 1979). Adsorption of dipalmitoyl lecithin (DPL) from emulsion in physiologic saline by respirable sized quartz dust and kaolin dusts, and consequent diminution of the dusts' hemolytic and macrophage cytotoxic potential have been reported (Wallace, et al, 1985). This report presents additional data on the cell-free in vitro phospholipase A2 enzymatic digestion of dipalmitoyl lecithin adsorbed on a quartz and a kaolin respirable sized dust (Wallace, et al, 1988) to investigate mineral specific differences in the rates of digestion and of consequent restoration of dust membranolytic potential. Respirable crystalline alpha quarts used was eighty percent smaller than 5 micorometer aerodynamic diameter with a nitrogen adsorption specific surface area of 3.97 m2/g. Respirable kaolin dust was ninety percent smaller than 5 micrometer diameter and had a specific surface area of 13.25 m2/g.

Jan 1, 1988

By A. J. Barry

Two methods of testing anchorages of headed expansion-type mine roof bolts were investigated by the Federal Bureau of Mines to determine whether they are acceptable for general use. In both methods a load was applied to a tightened bolt with a hydraulic jack. A total of 80 tests, 40 using each method, was conducted in 4 test areas in 3 commercial coal mines. Electric resistance strain gages were used in all tests to indicate true bolt load as the bolt was tightened and when an additional load was applied with the hydraulic jack. The results indicate that: 1. The relationship between the true bolt load and the jack load will vary according to the test method until the two loads become equal. The bolt load-jack load relationship below this point can be determined only with strain gages. 2. The point at which the two loads become equal can be estimated by noting the load when the hardened washer becomes loose in one method, and when the bearing plate becomes loose from the roof in the other. It also can be approximated for either method of testing by noting the load when the first abrupt change in the slope of the jack load-bolt displacement curve occurs. 3. The anchorage characteristics of the test bolt can be determined from the data obtained from either method by examining the slope of the jack load-bolt displacement curve above the point at which the true bolt load is equal to the jack load.

Jan 1, 1960

By H. W. Davis, Richard J. Lund

"In presenting the results of this survey on consumption of ferrous scrap and pig iron for the year 1935 the Bureau of Mines, responding to requests from industry, seeks to fill a major gap that has long existed in the field of metalliferous raw-material statistics. This type of information is designed to meet the needs of: (1) Consumers of ferrous scrap. including operators of blast furnaces, steel mills, ferrous foundries, and rolling mills; (2) marketers of scrap iron and steel, including large brokers who sell, and dealers who collect, prepare, and sell the material; (3) large scrap producers; (4) producers of iron ore, with which scrap competes indirectly; and (5) other individuals and agencies interested in more general economic analysis, since the scrap market has repeatedly been cited as one of the most sensitive of all industrial barometers, If the survey prover as useful as now seems probable, it will be continued annually with possibly an enlarged scope of treatment.The Bureau appreciates that its first efforts in this field may not meet all expectations: but it hopes to develop gradually, through suggestions, advice, and criticism from the industrial groups most interested, a type of analysis that will accord closely with technical processes and best meet the needs of all groups vitally interested in supplies and use of ferrous scrap. Constructive criticism and suggestions from industry regarding improvements to be desired in the conduct of future surveys on this subject will therefore be warmly received by the Bureau."

Nov 1, 1936

By J. W. Montoya

The chemical, mineralogical, and physical properties of berylliferous tuff from Spor Mountain, Utah, were determined in laboratory research conducted by the Bureau of Mines. Two beryllium-bearing minerals--a hydrated form of bertrandite and a berylliferous saponite--were found to be present in the tuff. Each of the beryllium mineral forms predominated in samples from certain areas of the district. The possibility of practicably separating the beryllium minerals from the tuff by physical methods appears remote because of the complexity and nature of the mineral associations. Beryllium mineralization in the region occurs in a rhyolitic tuff usually overlaid by unaltered rhyolite. The beryllium is distributed erratically throughout the tuff in individual mineralized bodies. Many samples of mineralized tuff were examined and found to contain from 0.2 to 1.8 percent BeO. All samples contained a hydrated form of bertrandite that was nearly cryptocrystalline, whereas samples from one area also contained a berylliferous saponite of variable beryllium content. Neither mineral has been previously reported, although related bertrandite-like minerals have been found in the U.S.S.R. and berylliferous minerals of the montmorillonite group have been synthesized. Most of the minerals of the tuff are finely crystalline, intergrown, and have similar densities. The complexity and intimacy of the mineral associations, the difficulty of achieving effective mineral liberation, and the highly friable nature are characteristics that lead to the conviction that tuff of the type examined cannot be effectively concentrated by gravity, magnetic, electrostatic, attrition, washing, sizing, or flotation methods.

Jan 1, 1962

By Jon K. Ahlness

The Bureau of Mines, in cooperation with the Institute of Mineral Research of Michigan Technological University, and the Upper Great Lakes Regional Commission, conducted an investigation of electronic sorting of native copper ore from Upper Michigan. This report is based on research by the Institute of Mineral Research under contract to the Bureau. The test program evaluated the use of belt and rotary sorters on various size and grade fractions of ore. Both plant-scale sorting and lab sorting tests were run. The plant sorting objectives were to determine the sortability of different ores and the efficiency of the electronic ore sorters. High-and low-grade ores from both conglomerate and amygdaloid types were separated into four size fractions. The two larger sizes were sorted on belt sorters and the two smaller ones on rotary sorters. Copper recoveries ranged from 20.0 pct from a feed grade of 0.40 pct to 80.3 pct from a feed grade of 1.08 pct. Lab sorting tests of conglomerate ore were run to determine the efficiency of a belt sorter equipped with a second sensing coil located above the belt and to determine the sorting characteristics of larger ore size fractions than those used in the plant sorting. Copper recoveries from the combined feed sizes ranged from 47.0 pct from a feed grade of 0.13 pct to 96.8 pct from a feed grade of 4.87 pct. For all the ore types except one, it was found that the copper recovery increased with the feed size.

Jan 1, 1980

By Thomas M. Barczak

Longwall operators are again pushing the envelope in terms of life expectancy for longwall shields. State-of-the-art shields are now expected to last more than 60,000 loading cycles, twice the life expectancy compared with those of a decade ago. A review of trends in shield design shows that shields continue to increase in both size and capacity. Some state-of-the-art shields now weigh over 30 tons and provide up to 1,200 tons of support capacity. Although life expectancy has increased and modern shields are structurally more reliable, premature failures do still occur. This paper provides an engineering and operational assessment of shield design and provides key points to observe in what causes premature shield failures. Design practices to improve structural margins of safety that will prevent premature failures from occurring are also examined. A survey of recent shield failures is provided, as well as trends in shield design and how they might impact the performance and longevity of a shield. Hydraulic failures are more common than structural failures. Although hydraulic failures occur on all aging longwall shields, they often go undetected for long periods, resulting in degraded support capacity that can lead to serious ground control problems. The fundamentals of shield hydraulics are described in order to evaluate hydraulic failures that plague all shields at some point in their service life, and practical methods to detect hydraulic failures are examined. The paper concludes with recommendations for inspecting damaged shields and safety precautions regarding their continued use.

Jan 10, 2000

Reduce dust at the auger mine face by modifying airflow patterns, around the minim machine. Approach Limited clearance between an auger miner and the mine root restricts airflow across the face and causes dust rollback. Directional sprays arc used to direct air across the face, thereby reducing dust rollback and increasing dust dilution (fig. 1). Laboratory and underground studies were used to test and optimize effectiveness of the directional sprays. Results of Laboratory Study Laboratory experiments were conducted in a simulated auger gallery equipped with a full-scale mock auger miner and bridge conveyor. A dual curtain configuration was used to direct the, ventilation, which averaged 2,700 cfm throughout the experiment. Testing variables included spray location, pressure, spacing, orientation, and number. Figure 2 shows the optimized directional spray system, also called the auger clearer spray system. The system consists of three sprays mounted alone the intake side of the miner. Sprays arc spaced 16 to 24 inches apart, and angled 30° toward the return side of the miner. The 24-inch spacing moved about 7% more air across the face than the 16-inch spacing; however, it resulted in some additional misting on the return side of the miner. A 30° orientation was more effective than a 60° orientation for moving air across the face and minimizing misting on the return side of the miner. Flat fan sprays arc used because their spray paths arc not obstructed by the top of the miner and mine roof, A 50° fan angle is used to minimize misting on the intake side of the miner.

Jan 1, 1989

By R. V. Ramani, V. T. Burgos, J. A. McClay

Summary Cost models have, long been confined to the accumulation and analysis of static-data.. While historical and time study data are valuable for control of existing operations, for new systems and equipment, and for projections, they need to be adjusted or modified. The availability of computer-oriented systems simulators provide yet another method for costing these systems and equipment. This investigation has introduced a concept whereby continuous, variable data can be assimilated and analyzed through the combination of an economic analysis model, which includes a direct costing capability, with a systems simulator. This tandem operation permits increased flexibility and greater atten¬tion to detail in the evaluation of mining systems. The direct costing process is carried throughout the majority of the model operations. Labor and capital costs may be computed directly, even in the absence of the systems simulator, while operating costs re¬quire input parameters, at present, from the subsystems of the Master Design Simulator. Since the costs computed are based on the perfor¬mance of each individual machine unit, the model may be used to evaluate equipment compatibility, system interaction at the mining face, and the effect of system elements on total mining costs. Additional applications of the cost model include the following: 1. Complete mining systems may be evaluated, over their economic life, to determine the feasibility of a profitable operation. 2. Costs associated with mining various segments of the coal deposit may be computed as a guide to planning the mine layout and scheduling the sequence of operations or acquisition of new

Jan 1, 1975

Studies on coal mine drainage sludge densification have led to the following conclusions: 1. Coal mine waters containing iron principally in the ferrous (Fea+) state can be treated by a modification of the commonly practiced lime neutralization process to yield a ferromagnetic sludge. The sludge, presumably composed in large part of a hydrated ferrosoferric oxide (Fe304.xH20), is much denser and faster settling than the ordinary "yellowboy" sludge obtained by lime neutralization and aeration at ambient temperatures. 2. The magnetic sludge preparation technique involves (quantitative) precipitation of iron (largely as Fe(OH)2) by the addition of hydrated lime to a pH of 8.5, separation of the resulting sludge from the aqueous phase, and heating of the sludge concentrate to at least 80 C (176 F), preferably higher, followed by mild aeration. 3. Magnesium, present as Mg2 in most coal mine drainage waters, inhibits the formation of the magnetic sludge. This inhibition can be adequately minimized by keeping the pH below 9.6 during lime addition (thus avoiding the coprecipitation of Mg(OH)2) and by separating the sludge from the bulk of the aqueous phase before the heating step, as indicated in (2) above. 4. Aluminum, commonly present in coal mine drainage waters, also inhibits the formation of the magnetic sludge. This inhibition is of practical significance when the molar ratio of aluminum/total iron is greater than 0.18. Below this value, sludges are still appreciably magnetic, but are bulkier and slower settling than those obtained when aluminum is absent. Unlike magnesium inhibition, aluminum inhibition cannot be minimized by the scheme indicated above, since aluminum precipitates as Al(OH)3 near pH 4 and remains dispersed within the sludge. 5. The limitation on aluminum content is probably the most serious restriction affecting the feasibility of the magnetic sludge process as presently conceived. Nevertheless, a limited review of available water quality data has indicated that, in terms of relative acid and iron loadings, a significant number of major coal mine discharges in the eastern Ohio River basin may be amenable to treatment by a magnetic sludge process. 6. Data from tests on the use of magnetic seeding materials indicate that seeding did not enhance the formation of a magnetic sludge under the experimental conditions employed.

Jan 1, 1971

By D. B. Gawthrop

"In connection with the proposed use of Cordeau-Bickford to fire L.O.X. (liquid oxygen explosives) in well drill holes, the question has arisen as to the effect of very low temperatures on (1) the rate of detonation of Cordeau-Bickford; (2) the sensitiveness to detonation of its TNT filling; and (3) the lead covering of Cordeau-Bickford.The Cordeau-Bickford used in this investigation was the standard 6 mm. size, such as is regularly used in blasting, and was manufactured and furnished by the Ensign-Bickford Company, Simsbury, Conn. All pieces tested were taken from rolls, all of which were from the same melted batch of TNT in order that all the pieces tested might be as nearly identical as possible.Different portions of this Cordeau-Bickford were tested plain (not countered), countered, and double countered. The countering and double countering was carried out by the manufacturer prior to shipment.The determination of the temperature at the instant of making a test was accomplished by the use of a Leeds and Northrup potentiometer and copper constantan thermocouples. Each couple was made from No. 28 B & S gage wire with short junctions. One junction was inserted in a hole drilled by a No. 60 drill through one lead wall of the Cordeau-Bickford to approximately the opposite wall, so that this junction was in the center of the TNT filling while the other junction was immersed in ice water. The potentiometer readings in millivolts were converted to °C. from the calibration curve of the thermocouple wire,"

Jun 1, 1924

By C. L. Wright

In 1904 the Government began a series of fuel-testing investiga- tions at its fuel-testing plant at St. Louis, Mo. These investigations, which were placed under the supervision of the United States Geo- logical Survey, included chemical analyses, steaming tests, gas- producer tests, briquetting tests, coking tests, and washing tests of samples collected from the various coal fields of the country. The specific purpose of the investigations was to analyze and test the coals and lignites in the United States, in order to deternime their fuel values and the most efficient methods of utilizing them for different purposes. Part of the fuel-testing plant, including the briquetting equipment, was moved to Norfolk, Va., in 1907, and the fuel-testing investiga- tions were made one of the divisions of the technologic branch of the Geological Survey. In 1908, after the close of the Jamestown Exposition, most of the fuel-testing equipment was removed to its present location at the Pittsburgh experiment station, Fortieth and Butler Streets, Pittsburgh, Pa. In 1910, an act of Congress, effective July 1, established the Bureau of Mines in the Department of the Interior and authorized the transfer to this bureau of the fuel-testing investigations that had been carried on by the technologic branch. Bulletins presenting the results of various inquiries and investiga- tions relating to briquetting have been published by the Geological Survey and the Bureau of Mines. As the supply of some of these bulletins is exhausted, the Bureau of Mines has decided, instead of reprinting them, to publish the more important facts they contain

Jan 1, 1913

By E. J. Gleim

The construction of explosion-proof electric mine equipment for operation in gassy coal mines of the United States was begun as early as 1903. In 1.906, similar equipment with special protective devices was built for export. An investigation of explosion-proof motors was conducted by the United States Bureau of Mines during 1910 and 1911. In other words, this was among the first efforts of the Bureau directed toward the saving of life and property subsequent to its establishment by act of Congress in 1910. In these early motors, those with special devices for relief of explosion pressures predominated. At that time it was generally considered that, by providing for pressure relief, the enclosures could be made lighter in weight because of the lower explosion pressures developed within.

Jan 1, 1954

PURPOSE: Evaluate practical technological advances in hearing protective devices for use in different mining environments. RESEARCH SUMMARY: Previous NIOSH research shows that miners develop hearing loss much more quickly than nonoccupationally noise-exposed individuals. Also, miners experience a greater severity of hearing loss than would be expected for nonoccupational noise-exposed persons of the same age and sex. As described in the National Occupational Research Agenda, problems created by occupational hearing loss include (1) the reduced quality of life due to social isolation and unrelenting tinnitus, (2) impaired communication with family members, the public, and coworkers,(3) a diminished ability to monitor the work environment (e.g., warning signals, equipment sounds, etc.), (4) lost productivity and increased accidents resulting from impaired communication and isolation, and (5) expenses for workers? compensation and hearing aids.

Jan 1, 2000

By Joseph Cervik, Gerald L. Finfinger

The Bureau of Mines conducted an experimental degasification project in Island Creek Coal Co.'s Virginia Pocahontas No. 5 mine. Methane from the over- lying Pocahontas No. 4 coalbed was entering mine workings in the Pocahontas No. 3 coalbed through fractures in the roof rock. Small-diameter (1-5/8-inch) holes were drilled into the overlying coalbed to reduce the gas pressure and intercept methane flows, which were piped to the surface through an under- ground 6-inch-diam steel pipeline. The total methane flow rate from the vertical holes averaged 150,000 ft3/day for the first month. Methane flows into the mine were reduced by 47 pct, thereby demonstrating the effectiveness of this form of degasification in reducing ventilation requirements and providing a safer working environment.

Jan 1, 1979

By Joan T. May

Anhydrous methods were tested for the extraction of beryllium from low-grade source materials. The purpose of the investigations was to find new extraction processes that are applicable to domestic ores. Beryl, helvite, and phenacite materials containing from 0.1 to 2.8 percent BeO were used as starting materials for direct halogenation tests and pretreatment followed by halogenation. The results of the investigations showed that direct fluorination and carbide-chlorination are two practicable methods that can be applied to low-grade concentrates. Treatment of concentrate-carbon mixtures with anhydrous hydrogen fluoride extracted 99 percent of the beryllium in the concentrate; the soluble fluoride product, converted to an oxide, contained 70 percent BeO. Chlorination of beryllium-silicon carbide, prepared from low-grade concentrates, extracted beryllium into the volatile chloride product.

Jan 1, 1962

By Philip B. Lorenz

A Bureau of Mines feasibility study on the use of tracer pulses to assess the degree of fracturing in an underground formation consisted of three phases: 1. A laboratory study on sand packs and open tubes, which developed a correlation between dispersion of the pulse and size of the flow channels. 2. A test on a retort, 11 feet in diameter and 45 feet high, packed with shale rubble. Void volume was measured, but evaluation of channel size was not possible because of interference from the space unoccupied by the matrix. 3. A field test on an explosively fractured shale formation. Pressure, flow, and transit time led to qualitative estimates of fracture pattern, but quantitative detection of dispersion in the formation was overwhelmed by dispersion effects in the well.

Jan 1, 1973

By C. A. Komar

Hardness, tensile strength, and impact toughness of dry and brine-saturated sandstone specimens were measured at ambient, cryogenic, and elevated temperatures as a measure of the relative stability of reservoir rocks for subsurface disposal of liquid wastes. Hardness measurements were inconclusive. Tensile strength and impact toughness were significantly higher at -320° F than at ambient temperature, but were relatively unaffected at 700° F. Impact toughness was reduced by subjecting the specimens to three cycles of rapid temperature changes (thermal shock) over a 1,000° F range. Tensile strength of brine-saturated sandstone was less than that of dry sandstone. Based on results of the tests, reservoir sandstone likely would be stable if exposed to extreme temperatures of liquid wastes, although rapid changes in waste temperatures should be avoided.

Jan 1, 1971

By T. H. Davis

Twelve laboratories from the Western United States and Canada participated in radon progeny intercomparison measurements at the U.S. Bureau of Mines radon calibration facility in March 1987. The participants intercom pared grab-sampling and automated equipment methods at high and low concentrations of radon progeny and condensation nuclei (CN). The objective of this intercomparison was to determine if the measurement procedures and equipment of the North American facilities are equivalent. The sampling results showed good agreement among all participants. The standard deviation for the working level measurements was less than 3.5% for 1.70 working level (WL) and less than 8.8% for 0.21 WL. This relatively good agreement was achieved by using alpha standards calibrated by National Bureau of Standards (NBS) and by closely checking and monitoring airflows.

Jan 1, 1989

By B. J. Scheiner

Silver ores from the Candelaria District, Nevada, and Round Mountain District, Colorado, were investigated mineralogically and metallurgically. Silver minerals of four distinct groups were identified: (1) silver sulfide; (2) argentojarosite; (3) silver contained in the iron oxide; and (4) manganese carbonate-oxide minerals, Electrooxidation and acid-chloride leaching techniques were investigated as means of altering silver minerals, and their effects on subsequent silver extraction were determined. Application of the knowledge obtained from mineral leaching studies resulted in development of a sulfur dioxide-sodium chloride leaching sequence for extracting silver from these types of ores. Silver extractions of 80 to 85 percent were obtained by leaching the ores with a sulfurous acid-sodium chloride system. This was an increase of 9 to 61 percent silver extraction over that obtained by conventional cyanidation techniques.

Jan 1, 1973