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By A. C. Smith

The U.S. Bureau of Mines conducted a study to evaluate the effect of underground mining conditions on the activation of automatic sprinkler heads. Sprinklers were exposed to liquid fuel fires in a rectangular tunnel at airflows of 0, 45, 90, 150, and 250 m/min to determine the effect of ventilation and fire size on the time to activation. As the airflows were increased, the time to activate the sprinklers for a given fire size increased. Also, as the fire size increased, the activation time decreased. Temperature profiles of the tunnel showed that the maximum temperature near the roof was shifted downstream as the airflow increased. Experiments to determine the effect of rated activation temperature and response time index (RTI) value on activation time showed that the time to activate increased with increasing activation temperature, and decreased with decreasing RTI value. Exposure to the mine environment showed little effect on the activation times in large-scale experiments, and no significant effect in laboratory experiments. The results showed that airflow can have a significant effect on the activation times of automatic sprinklers. This needs to be considered in the design of effective sprinkler suppression systems for ventilated areas.

Jan 1, 2010

The REL of 1 mg/m3 for respirable coal mine dust does not assure a zero risk for the development of occupational respiratory diseases among all miners exposed during a full working lifetime. Consequently, a medical screening and surveillance program that includes initial and periodic chest X-rays and spirometric examinations is important for the early detection of disease and the prevention of "material impairment of health or functional capacity" [30 USC 8 11(a)(6)(A)]. The medical screening and surveillance program is also useful for disease surveillance, which includes the tracking trends, the setting of prevention and intervention priorities, and the assessment of prevention and intervention efforts. NIOSH encourages both underground and surface coal miners to participate in the medical screening and surveillance program.

Jan 1, 1997

By Albert W. Deurbrouck

This Bureau of Mines report describes the washability characteristics of 13 coalbed samples collected in Colorado. Such data are needed to evaluate the quality of the coals of the West, where most of our low-sulfur-content coal reserves are found. Of the 13 samples included in this report, 11 had a total sulfur content of 1 percent or less. All of the samples contained low percentages of ash or could be readily washed to a desirable ash level with minimal loss of yield. The coals ranged in rank from high-volatile A bituminous to subbituminous B; nine of the samples were high-volatile C bituminous. The coalbeds ranged in thickness from 6 to 26 feet; the average was about 8 feet.

Jan 1, 1970

By Richard G. Sandberg

The Bureau of Mins, U.S. Department of the Interior, is investigating a hydrometallurgical procedure to conserve cobalt, nickel, and copper by recovering the metals from the matte byproducts of smelting Missouri lead ores. For want of adequate processing technology the mattes are now either unmarketable or marginally so. The procedure involves leaching with manganese dioxide and sulfuric acid to obtain copper, nickel, cobalt, lead, and manganese sulfates, and elemental sulfur as expressed by the following reaction: MS + MnO2 + 2H2SO4 ? MSO4 + MnS04 + S° + 2H2O, where M = Cu, Ni, Co, and Pb. The leach solutions, containing near theoretical amounts of sulfuric acid and manganese dioxide at 85° to 100° C, convert up to 98 pct of the cobalt, nickel, and copper in the mattes to sulfates in less than 2 hr. As they are formed, the cobalt, nickel, and copper sulfates are dissolved leaving a residue of lead sulfate, lead, sulfur, and gangue. The soluble metals are recovered from the leach solutions by caustic and sulfide precipitation, and the residue returned to the smelter for lead recovery. The manganese can be reclaimed from the spent leach liquor as manganese oxide and recycled to leaching.

Jan 1, 1979

By Lloyd A. Morley, Robert Stefanko

In addition to explosion-proof enclosures, the IEC has published recommendations: 1. 79-2 Pressurized Enclosures, 2. 79-3 Intrinsic Safety, 3. 79-5 Sand-Filled Apparatus, 4. 79-6 Oil-Immersed Apparatus, and 5. 79-7 Increased Safety. All these are valid methods of electrical hazard reduction and find wide use in industries other than mining. Magison (52) discusses in detail each technique and, therefore, such an examination will not be repeated. Two other systems, lamina and labyrinth, are but variations of common explosion-proof enclosures and, therefore, will not be cov¬ered. (34,35,46,53,54,61) By examining other national authorities' opinion, the following will investigate each system's applicability to coal mining. Intrinsic safety applies to any system which is incapable of re¬leasing sufficient energy to be an electrical hazard. (49) Not one foreign country contacted disagreed with the concept, and they find these systems totally acceptable. Only South Africa does not accept oil-immersed apparatus, but no reasons were given. (62) Healy (27) stated that Queenlands, Austrailia would accept all techniques, yet some were still to be employed. Japan specifications allow for all but sand filled. (42,43) Increased safety or Protection Type "e" is an approach in hazard reduction in which special design considerations are applied to ensure an extremely low probability of electrical or mechanical breakdown

Jan 1, 1974

By Thomas M. Barczak

This U.S. Bureau of Mines report describes methods to enhance the capacity, stiffness, and timber utilization of wood crib supports. Since stiffer supports minimize strata deflections that contribute to roof instability, efforts to maximize crib stiffness while maintaining stability through a wide displacement range should be a design priority. The stiffness and capacity of conventional crib designs, employing alternating layers of wood timbers that are loaded perpendicular to the grain, can be increased by increasing the interlayer contact area or by using higher strength wood. Contact area can be increased by using wider timbers or employing more timbers per layer. Concepts that provide parallel-to-the-grain timber loading will provide substantial increases in crib stiffness and capacity. Two concepts that utilize this principle are examined: (1) an original South African design that constructs wood cribs from preformed layers (mats) of timber where short blocks are oriented vertically between horizontal slabs; and (2) a design that employs full lengths of timber placed vertically in the interior of a conventional crib structure. These designs also provide more efficient timber utilization by providing greater support capacity per volume of wood used in the crib construction.

Jan 1, 2010

By S. J. Gerdemann

In support of its objective to improve mine safety, the Bureau of Mines has searched for better materials and systems to anchor roof bolts. TIlis report describes a study on the effects of mine waters upon accelerated gypsum, one of the materials under consideration. The accelerated gypsuw dissolved at an appreciable rate relative to an assumed 10-yr life span of a roof bolt. Surface orientation, initial ion concentration of a dissolving solution, and flow rate of the solu-tion had substantial effects on the dissolution rate. Factors such as water-cement ratio, accelerator content, wax capsule additions to the gypsum in cartridge-installed bolts, surface area, temperature, and curing duration had little effect. In an actual roof-bolt environment, dissolution will occur in static solutions to the solubility limit of gypsum (~2 giL) and cease, result-ing in minimal damage; but in flows of unsaturated solution as slow as 1 L per month, a loss of up to 10 pct will occur in 2 yr. Since miners cannot readily measure the flow or ion concentration of static-appearing water at every roof-bolt site, all such water must be assumed to be pure and flowing. It is recommended that gypsum-bonded roof bolts be confined to dry roofs only.

Jan 1, 1983

By J. D. Davis

On May 15, 1936, Congress authorized the Bureau of Mines to conduct certain studies, experiments, and. investigations of subbituminous coal and lignite.4/ Appropriations were made in July 19 7, and since that date an active investigation has been underway to complete the provisions of the act. Part of the investigation has included a comprehensive survey of the known properties of the lower-rank non-coking coals, and provisions were made to obtain more data on certain varieties. In line with this plan, a typical subbituminous coal was selected for an extended series of tests in the standard. Bureau of Mines-American Gas Association unit,5/ at the Central Experiment Station. This particular noncoking coal was the first one of its rank that had been tested in the apparatus; for this reason the results are of particular interest because the testing apparatus was originally designed for use in studying the coke- and gas-making properties of coking coals. The test as described below has been developed by the Bureau of Mines since 1927 through a cooperative agreement with the American Gas Association.6/ Ninety to 180 pounds of coal is heated in a circular retort, 13 to 18 inches in diameter, at wall temperatures ranging from 500°C. to 1,110°C. in 100°C. steps. All products are collected and measured; their physical and chemical properties are then carefully determined to ascertain the gas- and coke-making properties of the coal. During the last 10 years approximately 50 representative American coals have been tested in the Bureau of Mines equipment. The results on the first 30 coals and a complete description of the test procedure are contained in a joint publication of the Bureau of Mines and the American Gas Association.7/ The remaining twenty coals have been reported in Bureau of Mines reports as Technical Papers and Bulletins.

Jan 1, 1939

By C. H. Elder

A 5-hole pattern was drilled from the surface at a site near Oak Grove, Jefferson County, Ala., to degasify the gassy Mary Lee coal bed in advance of mining. Gas and water production was monitored for 1 year, 4 months to allow gas flow to stabilize fully. A thickened water stimulation treatment was designed and applied in one hole of the pattern to evaluate this degasification technique for the Mary Lee coalbed. A gas production rate of 70,000 fts/day after stimulation treatment indicates that the use of vertical boreholes coupled with hydraulic fracturing in advance of mining the Mary Lee coalbed would provide for more rapid degasification and could provide a possible source of natural gas.

Jan 1, 1974

By J. R. Bartels

Operation of underground coal mine mobile equipment is usually done in a restricted workspace with reduced visibility. This work environment puts machine operators in awkward postures for tasks that require awareness of their surroundings and fast reactions to avoid hazardous situations. Using experienced equipment operators as a source, researchers conducted an investigation that developed a method to gather data on the needs and practices of machine operators while controlling the machine and the reasons for needing particular operational cues. The method used was an interview technique including a survey questionnaire and visual aids. The data gathered defined operator cues and work positions for the cutting and tramming phases of remote controlled continuous mining machines used in underground coal mines. Analysis techniques to determine which cues an operator sees from a variety of positions utilizing a computer simulation is shown to be potentially useful to the mining industry for design of work practices and workplace layout and could impact equipment design and selection for improved worker safety. Conclusions indicate that the survey was a good research tool to collect data and helped investigators understand important visual cues. Using this information, researchers were able to analyze the visual cues an operator can see from a given work position and posture.

Jan 1, 2009

By R. C. Buehl

An experimental iron blast furnace of 3-foot-diameter hearth, producing about 12 tons of metal per day, was operated for 2 weeks with various proportions of anthracite replacing a corresponding amount of coke. The furnace operated well with anthracite in amounts up to 40 percent of the total fuel and produced metal of uniformly low sulfur and normal silicon contents. An increase to 50 percent anthracite during two attempts resulted in poor operation and the charge hung in the s haft of the furnace. INTRODUCTION Anthracite production in Pennsylvania decreased from 84,400,000 net tons in 1926 to 40,600,000 net tons in 1952, and there was a further decline in 1953 to 30,900,000 net tons. Employment in the anthracite industry dropped from 165,000 men working an average of 244 days per year in 1926 to 57,900 working an average of 163 days per year in 1953,3/ which has naturally resulted in considerable unemployment in the region. The industry is actively engaged in promoting new uses for anthracite to increase the demand and thus improve economic conditions in the region. One possibility is the use of anthracite to replace part of the coke for smelting iron ore in blast furnaces. The tests in this report were made to determine whether this use of anthracite would be feasible.

Jan 1, 1955

By A. B. Hooker

Investigations at the Pittsburgh Experiment Station have shown that the satisfactory operation of aflame safety lamp depends not only upon proper design and assembly of the lamp but upon the kind of fuel used, and that much of the trouble experienced with permissible flame safety lamps at mines is due to the common use of motor gasolines, none of which is suitable in the present types of permissible flame safety laps. This report gives the results of a limited study to determine what satisfactory fuels are available, the specification limits of such fuels, and to suggest modifications of assembly and care of the lamps to improve performance with any satisfactory fuel.

Jan 1, 1938

By R. E. Heithecker

The separation of enormous quantities of water produced with the oil in some West Texas fields necessitated the use of special equipment other than the regular lease tanks. Several methods were used with varying degrees of success. They include the water-trap, hay tank and gun barrel, gun barrel and settling tank, chemical and electrical-dehydration methods. The water trap which has been used extensively in the Hendricks field, and in some instances has been installed in the Yates field separates the water and. oil under high pressure before tile liquid and gas pass through the flow beam. The first trap was constructed and installed by the Southern Crude Oil Purchasing Co. in July, 1928. By July, 1929, approximately 300 traps were in use. Treating cut oil by running it through a hay tank was done quite extensively in the Roberts-Settles field, Howard and Glasscock Counties, Tex., and later the method was used in the Hendricks field. In July, 1931, there were 37 hay tanks in the Roberts-Settles field, treating the oil from 123 wells. The cut oil frequently was made acceptable to the pipe-line company by running it through the hay tank. In some instances, however, it was necessary to heat the oil, and occasionally both heat and chemicals were used before complete separation of the oil and water was obtained.

Jan 1, 1932

By W. L. Brien, O&apos

Molybdenum alloys with good strength properties at elevated temperatures were produced by the powder metallurgical internal oxidation method previously applied to tungsten and known as oxyreaction strengthening. Commercial molybdenum powders were blended with 0 to 10 pet of a reactive powder, ZrMo2. The effects of composition, blending procedure, and sintering conditions on strength properties at elevated temperatures were studied. Strengthening was attributed to zirconium in solid solution with molybdenum and to the presence of submicrometer particles of Zr02. Several alloys had tensile strength and stress-rupture properties com-parable with those of the best commercial alloys. The maximum tensile strengths obtained were 92 kpsi at 1,200° C and 53 kpsi at 1,316° C. The maximum stress-rupture life at 30 kpsi and 1,200° C was 145 hours.

Jan 1, 1974

By M. J. Beus

Researchers at the U.S. Bureau of Mines have developed personal-computer-based data acquisition, instrumentation, and mine visualization and modeling techniques to evaluate a mine accessway in a deep hard-rock mine in northern Idaho. These techniques were applied to a mine shaft in a large silver mine that has been in operation for many years. A very deep, rectangular, timber-supported shaft extending to depths exceeding 2.3 km (7,500 ft) had been deforming continuously as a result of nearby mining, resulting in operational problems. Preliminary visual observations and rock and support monitoring confirmed that severe diagonal distortion was occurring. Extensive field measurements and data analysis confirmed initial observations, provided insights into the cause of deformation, and defined a general approach to structural modeling. Computer analysis of the problem was initiated by developing a three-dimensional model of the terrain. This represented a volume of rock approximately 80 km3 (40 x 1010 ft3) and an area on the surface surrounding the mine 9 km2 (3 square miles). Based on this model, a three-dimensional, finite- element analysis was conducted to establish boundary conditions for sequentially more detailed two- and three-dimensional submodels of the shaft area. Results from the computer study are being used to develop new approaches to mine design and to provide design guidelines for deep mine accessways subject to severe rock-mass loading conditions.

Jan 1, 2010

By Stanley C. Rhoads

The Bureau of Mines investigated the complete ternary system K2 HfF6¬K2ZrF6-l.25 weight-percent HF at 40° C. In addition, solubility curves have been established at 25°, 30°, 500, 60°, and 70° C. These solubility data implemented a study of hafnium enrichment in feed solutions for liquid-liquid extraction processes.. Selected K2HfF6-K2 ZrF6-1.25 weight-percent HF mixtures were equilibrated in a constant temperature bath. Compositions of the equilibrated solutions and wet residues were established from combined hafnium and zirconium oxide and total fluorine analyses. All solubility curves were essentially parallel on triangular coordinates. At 40° C, the solid phase of the K2HfF6-K2ZrF6-1.25 percent HF system is a series of solid solution hydrates with K2HfF6-H20 and K2ZrF6.3H2O segments existing at the respective extremes. Since this system contains K2HfF6-H20 and K2ZrF6.3H20 segments, it is not ideal for simple separation of high-purity K2HfF6 from K2HfF6-K2ZrF6 mixtures by recrystallization. However, it would be useful for producing hafnium-enriched feed solutions from zircon concentrates for liquid-liquid extraction of hafnium from zirconium.

Jan 1, 1973

By Roy L. Grant

The Bureau of Mines investigated the up-and-down method with factorial designs to determine if shorter, and therefore less costly, trial sequences could be used. Although sequences of 50 trials are usually recommended, sequences of 20 trials were arbitrarily chosen for the experiments with permissible coal mine explosives described in this report. These explosives were fired from a cannon pointed into a flammable natural gas-air atmosphere at the Bureau of Mines Explosives Research Center gallery to ascertain their safety properties. The investigation demonstrated that the shorter sequences led to useful conclusions with a reduction in cost of the experimental program.

Jan 1, 1967

By Richard A. Winters

In 1987, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied the 6,022-acre Spring Basin Wilderness Study Area (OR-005-009) in order to evaluate its mineral resources. The study area is in Wheeler County about 13 miles southwest of Fossil, Oregon. No mineral resources were identified. The area is underlain by volcanic flows, domes and sediments ranging in composition from olivine basalt to rhyolite of the Clarno and John Day Formations. There are three mining claims in the study area, all apparently located for lapidary material. Samples of agate were of poor quality. Four of 13 alluvial samples, two inside and two adjacent to the area, contained gold; content ranged from 0.0000097 to 0.00416 troy ounce per cubic yard. About 23 percent of the Wilderness Study Area is covered by oil and gas lease applications.

Jan 1, 1988

By Noel N. Moebs

This report summarizes a Bureau of Mines study on the use of geotechnology to identify and reduce ground control hazards at slate quarry operations in eastern Pennsylvania. The major ground control hazard is falling rock, attributed to weathered bedding plane faults, which weaken quarry highwalls. It was demonstrated that these faults can be detected outside of the quarry perimeter using surface resistivity measurements. Falls of ice from quarry highwalls constitute a second major hazard, which requires water diversion as a basic control method. In situ stresses seemingly cause only minor problems in slate extraction although they could interact with developed stresses and lead to failure of barriers between quarries. Pull tests showed that rockbolts anchor firmly in slate and should prove effective in securing loose rock.

Jan 1, 1986

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