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By Donald P. Blasko

The Bureau of Mines investigated two areas of the Alaska Peninsula (Iniskin Peninsula and Becharof Lake) where oil and gas seeps were known to occur in an attempt to determine (1) whether the seeps are still active and (2) the amount of bitumen contained in the drainage leaving the seeps. The oil, water, oil-water, and gas were sampled and analyzed. Five oil samples were taken at four separate oil seeps. The API gravity of the oil ranged from 8.90 to 21.4° and the sulfur content was from 0.12 percent to 0.59 percent. Four of the seven gas samples obtained revealed fair high caloric values, ranging from 746 to 924 Btu/cu ft, and averaging 844 Btu/cu ft. A total of 44 water samples were obtained. Bitumen content of the water was as high as 9,773 mg/l at one seep, but averaged less than I mg/l where the seep-drainage water entered the Gulf of Alaska.

Jan 1, 1976

By V. Rajaram, S. Bhattacharya, M. F. Dunn

During a mine fire or other emergency, it may be desirable to reverse the airflow in order to provide an escapeway or to isolate a fire. Also, (in colder areas, the airflow may be reversed to prevent ice buildup. When reversing main mine fans, the mine operator usually does not know what operating characteristics of flow and pressure to expect. Laboratory a field tests of vane axial main mine fans in the 7- to 9-ft diameter size range were conducted to establish forward and reverse performance characteristics under controlled conditions and at typical mine installations. The data obtained suggest that reverse performance characteristics are dependent upon the blade angle and the hub to tip ratio. There is also evidence that reverse performance can be predicted for a family of blade angles and a given hub to tip ratio. Generally, quantity of air is 30% to 65% less in reverse than when operating in the normal forward mode.

Jan 8, 1983

By H. J. Heinen

A technique offering promise as a metallurgical processing sequence the recovery of molybdenum (Mo) from the sulfide mineral--molybdenite?was investigated. The method consists of two steps: (1) electrosynthesis of pure dimolybdenum carbide (Mo2C) from molybdenite (MoS2) and (2) interaction of Mo2C and molybdic oxide (MoO3) to produce pure molybdenum metal. Two molten salt systems were satisfactory for electrosynthesizing Mo2C. The first was a mixture of potassium chloride (KCl), potassium fluoride (KY), and sodium metasilicate (Na2SiO3), and the second consisted of sodium fluoride (NaF), KF, sodium tetraborate (Na2B4O7), and sodium carbonate (Na2CO3). Yields up to 0.42 gram of Mo2C per ampere-hour were obtained. The carbide, mixed with monitored amounts of MoO3, was converted to molybdenum metal of 99.9 percent purity by sintering at 1,500° C.

Jan 1, 1965

By Kenneth C. Stewart

This contract was directed toward a study of the attenuating properties of earmuffs as worn by miners. Two attenuation measurement procedures were utilized. Human subjects were tested in a diffuse sound field according to threshold shift procedures recommended by the American National Standards Institute and a physical measurement procedure was accomplished in the same diffuse field on the same human subjects with microphones placed simultaneously on the inside and outside of the muffs. All measurements were obtained in one third octave of random noise. The results of the study indicated that physical and psychophysical attenuation measurements are in essential agreement at frequencies from 125 Hz to 2 KHz. Above 2 KHz the psychophysical measurement demonstrates larger amounts of attenuation than the physical measurement. The difference in attenuation ranged from approximately 7.0 dB to 9.0 dB at frequencies of 4 KHz and above. A possible explanation for the observed differences in attenuation has been presented.

Jan 1, 1980

By F. S. Karn

Measurements were made of the flow of helium, methane, ethane, butane, and toluene through thin disks of coal. All measurements were made on a dense layer in the Pittsburgh seam identified as attritus. Flow increased with pressure differential and temperature. At room temperature and a pressure differential of 1 atmosphere flow rates along the bedding plane of Pittsburgh seam coal were helium 881 X 10-10 cm2 sec-1, methane 1.2 X 10 -10 cm2 sec-1, ethane 0.54 X 10-10 cm 2 sec-1, n-butane 0.35 X 10-10 cm2sec-1, and toluene 3.8 X 10-10 cm2sec-1. Flow rates were 50 percent lower across the bedding plane of the coal than along the bedding plane. Activation energies were 3.9 kcal mole-1 for helium and 13.6 kcal mole-1 for methane, with diffusion measured either along or across the bedding plane.

Jan 1, 1970

By Andrew B. Cecala

The U.S. Bureau of Mines has designed and tested a system called the Bag and Belt Cleaner Device (B&BCD) to reduce dust levels in and around the bag conveying and stacking process. The device physically cleans either 22.7 kg (50 lb) or 45.4 kg (100 lb) paper bags by using a combination of brushes and air jets. It is completely self-contained and is kept under negative pressure by a baghouse to ensure that dust and product removed from the bags during cleaning does not flow into the work environment and contaminate workers. The bags travel through the device on a chain conveyor, which permits any product or dust cleaned from the bags to fall into a hopper at the bottom of the device and be recycled back into the process via a screw conveyor. Once exiting the B&BCD, the outside of the bags and the conveyor are essentially product and dust free. The B&BCD was evaluated at two mineral processing plants to determine reductions with the device in use. The results of both field evaluations showed that the amount of product removed from the outside of the bags varied from 77 to 93 pet.

Jan 1, 2010

By P. D. Laverty

The U.S. Bureau of Mines treated mixed and contaminated super alloy scrap by pyrometallurgical and hydrometallurgical methods to separate and recover metal values. Best results were obtained by leaching Zn-treated or atomized scrap with HCI-02 at 9SO C and 50 psig 02' This resulted in dissolving approxi-mately 98 pet of the AI, Co, Cr, Cu, Fe, Mn, Ni, and Zn while rejecting over 98 pct of the Mo, Nb, Ta, Ti, W, and Zr as an insoluble refractory residue. Chlorine was successfully substituted for HCI to leach Zn-treated scrap but was unsuccessful for leaching atomized scrap. The leaching solution was treated by pH adjustment and hydrothermal precipitation at 2000 C for 4 h to remove AI, Cr, Fe, and other contaminants as a filterable precipitate. Recovery of Co and Ni would be accomplished by solvent extraction and e1ectrowinning. Chromium recovery as a ferroalloy was demonstrated.

Jan 1, 1989

By Stephen P. Signer

This paper presents an overview of laboratory and field tests on approximately 250 fully grouted roof bolts instrumented with strain gauges in order to study loading behavior. Laboratory work included pull tests, time-dependent tests, and shear tests. The field tests were conducted in 14 different mines extracting different commodities. However, because of the focus of this publication, only the results of tests in 9 coal mines are reported here. In the field tests, all but 14 bolts were loaded by rock movement; these 14 bolts were tested using pull gear. The variables studied included anchorage length, mechanical interlock, time-dependent behavior, shear, installation load, loading rate, and maximum load level. Such information will improve the understanding of the behavior of resin-grouted bolts, which in return will enhance the safety of miners by reducing the occurrence of rock falls. The influences of geology, overburden depth, entry width, mining-induced stresses, and bolt spacing are not described.

Jan 10, 2000

By Richard G. Burdick

The Bureau of Mines conducted this research to determine the feasibility of using soil redox measurements, a relatively new method in mining geophysics, to locate or define a variety of conditions that are hazardous or otherwise of interest to the mining industry. The method was used in three widely separated areas in an attempt to de- fine subsurface concentrations of methane, the edges of coal-burn areas, and a hydrothermal vein set. Both a description of the method used and test cases are given in this report.

Jan 1, 1982

By F. J. Gallagher

"INTRODUCTION The purpose of this circular is to present information on the construction and use of reinforced rubber-jatketed tubing and insulatiag air-line couplings in coal mines Where Airdox is used for breaking coal in order to eliminate: insofar as possible, arcing at the face between Airdox tubing and the track or other face equipment.ACKNOWLEDGMENTThe information given by the W. M. Hales Co., Chicago, Ill and the Peabody Coal Co., Taylorville, Ill., regarding the construction and use of rubber-jacketed tubing and insulating couplings in gratefully acknowledged. GENERAL INFORMATIONSince its introduction into coal mines, the use of Airdox has grown in popularity, especially in the Indiana and Illinois coal fields. Its use permits breaking dawn coal on shift, whereas the use of explosives for blasting coal on shift is prohibited by law in those States. Many of the hazards connected with the use of explosives are eliminated. The accident experience in the use of Airdox has been excellent with respect to the number of fatalities or serious injuries per million tons mined.The Federal Mine Safety Code specifies that Airdox lines should be grounded at the compressor and at other points of low resistance along the lines but should not be connected to tracks, pipe lines, or other possible power conductors. The majority of operators in the Indiana and Illinois coal mines, in which Airdox is used, approve the precautions embodied in the code regulationsIf Airdox lines are grounded in accordance with the Code, the following hazards persist:"

Sep 1, 1949

By Irving Hartmann, Edward Thomas

"INTRODUCTION Adoption of rubber-tire shuttle cars underground in conjunction with mobile coal-loading machines has introduced new problems in the control of dust on mine roadways. Where this type of loading and transportation is used, development and extraction are generally rapid, with the result that much coal is spilled from the shuttle cars during normal operation, Coal in the roadways from this source and from sloughing of the ribs is ground to fine dust by the wheels of the 'shuttle cars and by the treads of the loading and mining machines. The coal dust usually is somewhat contaminated by pulverized rock, and the mixture could not be loaded with the run-of-mine coal without undue contamination of the product even if it were cleaned up promptly.The presence of large quantities of fine, loose dust, which is constantly stirred up and kept in suspension in air by the traffic, constitutes a grave explosion hazard, reduces visibility along the roadways, and is physiologically harmful to the workmen who breathe the air. From the operating standpoint the loose material is undesirable along the roadways because it provides poor traction for the trucks and thereby increases wear and power consumption. The dust-explosion hazard could be eliminated or reduced by frequent application of sufficient rock dust on the roadbed; but this would not remedy the other difficulties, and in fact it might intensify them. Where practicable, the most direct and effective safety measure is to clean up and remove promptly all dust that forms and settles on the roadways. Unfortunately, in many cases this procedure is not feasible. A third Suggested remedy is to prevent dispersal of the dust into the air and to promote its consolidation on the floor by wetting the dust particles.During the past few years several mines have used calcium chloride on shuttle-car roadways to allay the dust thereon. When exposed to the' humid atmosphere of the mine this salt absorbs Moisture from the air and deliquesces, and in this way wets the dust on the floor of the roadway. In a survey conducted in coal mines in southern West Virginia and in eastern Kentucky where calcium chloride has been in use, somewhat conflicting re- ports were received regarding the merits of the application, and several operators have abandoned the practice either because of actual or assumed disadvantages. The purpose of the study described in this report was to collect and correlate evidence and, on the basis of experimental data obtained in the field and in laboratory tests, to present a clearer picture of the factors involved in the allaying of dust by use of salts."

Sep 1, 1945

By J. C. Johnson

In situ stresses are important input data for the design of safe, stable stope layouts and extraction sequences. However, it is commonly assumed that normal and shear stress gradients in a stress field are negligible and, consequently, that stresses are uniform throughout the region of analysis. To evaluate these assumptions and to provide input data for an analysis of a shaft pillar mining plan, in situ stresses were measured at the Homestake Mine, Lead, SD, using overcoring on hollow inclusion cells and borehole deformation gauges. These measurements were used with conventional least squares, best fit data reduction schemes. The results showed that normal stresses within the shaft pillar were less than, but comparable to, those estimated from finite-element modeling. Shear stresses were an order of magnitude less than normal stresses and varied considerably from site to site. Possible causes of this variability include effects of scale, elastic moduli, anisotropy, and axial strain. Because of the variability, it is not possible to determine the magnitude of horizontal stress gradients.

Jan 1, 2010

By Robert R. Stein

Occupational noise caused by the rock drills used in mining was investigated by the U.S. Bureau of Mines. Using a large reverberation chamber and an automated drill test fixture (ADTF), the sound power levels of mining drills were measured to determine if there are types of drills that are advantageous from a noise production standpoint. Test results show that while there are not large variations among types of drills, there are still some choices that could produce a positive effect on overall noise exposure. It is also shown that lower noise exposures are possible using larger drills because of higher production rates and better operator positioning.

Jan 1, 2010

By H. E. Powell

The smelting of brass and bronze generates a dust composed primarily of zinc oxide, with lesser amounts of other metal oxides, such as copper, lead, and tin. The small quantity of this waste generated by individual smelters and the relatively low unit value of the contained metals, suggests the desirability of reclaiming the metals onsite or at some nearby point. The Bureau of Mines has developed a process that fits these requirements. The technique consists of (1) dissolving zinc and copper from the dust with sulfuric acid, (2) recovery of copper by cementation, (3) recovery of zinc as zinc sulfate crystals, and (4) recovery of lead and tin as a salable residue. Alternatively, zinc may be recovered by electrodeposition. Free acid is recycled and no major pollution problems are generated by the process.

Jan 1, 1972

By Elizabeth G. Baglin

Research was conducted by the Bureau of Mines to determine the feasibility of using electrokinetic densification to dewater Bayer process red mud, magnetic black mud prepared by pressure digestion of red mud in the presence of ferrous sulfate, and magnetic black mud formed by simu-lated Bayer digestion of Jamaican bauxite with added ferrous sulfate. Tests showed that the solids content of presettled muds could be increased from 25 pct to approximately 40 to 48 pct by gravity draining followed by electrodewatering for approximately 48 h. Electrodewatering may not be practical because of increased reagent and processing costs and because the muds must be thoroughly washed prior to electrodewatering to remove dissolved ions and decrease mud conductivities.

Jan 1, 1988

By D. R. Corson

The Bureau of Mines instrumented two similarly backfilled stopes--one filled in the normal manner and the other with the fill densified using vibratory compactors--to evaluate the effect of fill compaction on subsequent vein-wall closure proposed as a adjunct process for strengthening cemented fill. Hydraulic pressure cells to monitor pressures within the fill and mechanical closure devices to measure vein-wall movement and the procedure for their installation are described. The field compaction work was generally performed manually by utilizing small commercial concrete vibrators. A prototype immersible vibrator using slusher cables to propel the vibrator in the stope was used on several lifts of fill. Although compaction efforts were less effective than anticipated in increasing the final density of fill, analysis of the field data does indicate somewhat improved strain characteristics and an increased pressure buildup for the densified fill. The effects of a prolonged period of inactivity and of rock burst occurrences in the immediate area are also reflected in plots of strain and pressure within the two instrumented stopes.

Jan 1, 1971

By John D. Corrick

Three species of chemosynthetic iron- and sulfur-oxidizing autotrophic bacteria have been isolated from the leaching waters of copper mining areas. These species are: The sulfur-oxidizing Thiobacillus concretivorus, the iron-oxidizing Ferrobacillus ferrooxidans, and a sulfur- and iron-oxidizing bacterium closely resembling Thiobacillus ferrooxidans, INTRODUCTION Among several suggested new processes for treating marginal ores in the United States, none is more intriguing than the possibility of extracting metals from low-grade materials by the action of microorganisms One phase of a Federal Bureau of Mines investigation toward developing such a procedure was to isolate and identify specific chemosynthetic iron and sulfur. oxidizing autotrophic bacteria native to certain domestic copper deposits where leaching is practiced. The bacteria or microorganisms considered important to this investigation are those capable of producing solutions of ferric sulfate and sulfuric acid. Solutions of this type are excellent solvents for some copper minerals By establishing the presence of these bacteria at certain copper-leaching areas, strength would be given to a theory that microbial activity is partly responsible for the oxidation that takes place at these areas. Their presence also advances possibilities for controlled use of microbial action in metal extraction processes. Leathen4/ has demonstrated that one of the chemosynthetic iron-oxidizing bacteria, Ferrobacillus ferrooxidans, can oxidize 200 parts per million of ferrous iron to the ferric state in 3 days,

Jan 1, 1961

By Ann G. Kim

The Bureau of Mines investigated factors that influence the formation of methane and other hydrocarbon gases in coal, which is an integral part of the coalification process. Coalification begins with a biogenetic stage in which plant debris decomposes and peat is formed; methane and CO2 are the predominant gases produced during this stage. During the diagenetic stage of coalification hydrogen and the hydrocarbon gases methane, ethane, ethylene, propane, propylene, butene, iso- and normal butane, and pentane are formed by dissociation of the organic material. Methane may also be produced by a secondary reaction of hydrogen with unsaturates or by the reduction of CO2. The gas contained in coalbeds is a mixture of methane, C2 through C5 alkanes, CO2, 02, N2, H2, and H2; its heating value is equivalent to that of natural gas. The gas content of coal depends on many variables, but an empirical relationship between adsorptive capacity, rank, and depth has been observed.

Jan 1, 1978

By C. L. Klingman

In extracting helium from natural gas at Bureau of Mines helium plants, a continuous analysis of the helium content of inlet and outlet gas streams is required to determine extraction efficiency. An analyzer, using established principles of gas chromatography to effect the analysis, has been developed by the Bureau of Mines to meet this need. It will record the helium content of inlet or discharge gases from helium-extraction plants every five minutes, continuously, without the attendance of an operator. A 25-inch column of activated charcoal is used as a partitioning agent; nitrogen is the carrier gas; and a hot-wire, thermal-conductivity cell is the detector. A 1.0 mv, strip chart indicates the unbalance of the detector cell, Sample size is 0.37 cc, and carrier gas flow rate is 75 cc, per minute. Significant improvements in helium extraction have been demonstrated by using the chromatograph in three helium-extraction plants.

Jan 1, 1961

By Alla D. Mah

The heat of combustion of TaC0.996 was determined by oxygen bomb calorimetry to be -302.8 ±0.4 kcal/mole. The corresponding heat of formation of TaC0.996 is -35.4 ±0.5 kcal/mole, and the calculated heat of formation of TaC1.00 is -35.5 ±0.5 kcal/mole.

Jan 1, 1965