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By L. C. IlsLey

The service given by a flame safety lame is twofold: It provides a safe light and it gives evidence of the condition of the mine atmosphere relative to the presence of methane and the deficiency of oxygen. Since the development of portable electric mine lamps, flame safety lamps are little used for lighting,but their use as detectors is as extensive and important as ever. A flame safety lamp in the hands of a trained user will definitely how methane concentrations as low as 1 percent, which in well below the lower explosive limit of methane and air. However, this does not always suffice, especially when making studies of mine ventilation, where it may be desireable to detect concentrations below 1/2 of 1 percent.

Jan 1, 1936

By L. C. IlsLey

[The service given by a flame safety lame is twofold: It provides a safe light and it gives evidence of the condition of the mine atmosphere relative to the presence of methane and the deficiency of oxygen. Since the development of portable electric mine lamps, flame safety lamps are little used for lighting but their use as detectors is as extensive and important as ever. A flame safety lamp in the hands of a trained user will definitely show methane concentrations as low as 1 percent, which in well below the lower explosive limit of methane and air. However, this does not always suffice, especially when making studies of mine ventilation, where it may be desireable to detect concentrations below 1/2 of 1 percent.]

Jan 1, 1936

By F. C. Houghten, R. R. Sayers, C. P. Yalaglou

"Introduction.Atmospheric conditions relative to high temperature and humidity are of great importance in mining, as well as in such allied fields as railroad and vehicular tunnels. An extended investigation into the effect of these factors on men has been in progress for some time, both in the field under actual working conditions, and at the Pittsburgh experiment station of the bureau in cooperation with the American Society of Heating and Ventilating Engineers and the U. S. Public Health Service.For several years one of the writers (Dr. Sayers) and L. Harrington, supervising mining engineer of the bureau, have been studying the effects of hot humid atmosphere in metal mines on the comfort and efficiency of the workers. Some of the reactions experienced in still and in moving saturated mine air at temperatures of 90 to 100°F., with men at rest are presented in a recent paper.****The present paper is based on experiments made under carefully controlled conditions to determine the relative feeling of warmth experienced by men in atmospheres of various degrees of temperature and humidity. The work was conducted by the research laboratory of the American society of Heating and Ventilating Engineers, at the Pittsburgh experiment station of the Bureau of Mines, in special physchrometric chambers built for this purpose. It was carried on under the direction of F. Paul Anderson, director of the laboratory, Dr. R. R. Sayers and A. C. Fieldner of the Bureau of Mines. The results given in this paper are for still air only. Investigations of the effects of moving air are being continued, and will be reported later."

Jan 1, 1924

By R. W. Freedman

The gas chromatographic method, devised by the Bureau of Mines for analyzing routine mine air samples, was compared with the infrared method used for confirmatory determination of methane in mine air. While maintaining the specificity of the infrared method for methane determination, the gas chromatographic method is more precise, much more rapidly performed, and more convenient.

Jan 1, 1968

By D. R. Flinn

The Bureau of Mines has studied the electrochemical parameters important to the preparation of coatings of the platinum-group metals. Using molten mixtures of sodium and potassium cyanides in an inert atmosphere, techniques have been developed that permit the preparation of baths for platinum, rhodium, and iridium electrodeposition. Cyclic voltammetric and slow sweep rate linear polarization techniques have been utilized to determine optimum potential and current values for preparation of plating baths and for the electrodeposition of coatings. Techniques are described for the deposition of platinum and rhodium coatings at near 100 percent anode and cathode current efficiencies, and for iridium at approximately 80-percent efficiency. Palladium deposition from these molten cyanide baths remains un-satisfactory. The chemistry of the palladium-containing cyanide bath is discussed. Examples of scanning electron microscope photomicrographs of typical platinum coatings are presented. Techniques are described for the preparation of platinum coatings on large objects.

Jan 1, 1982

By A. R. Rule

This report describes preliminary studies by the Bureau of Mines to develop a procedure for extracting the fluorine from low-grade fluorspar ores in which the CaF2 particles are finely locked in the calcite matrix. A combination of flotation beneficiation and pyrohydrolysis is applied to recover and to liberate the fluorine. Flotation of a finely locked high-calcite fluorspar ore containing only 11.7 pct CaF2 recovered over 92 pct of the fluorspar at a grade of 51 to 52 pct CaF2. Pyrohydrolysis of the flotation concentrate liberated nearly 90 pct of the fluorine as aqueous HF. By this procedure over 80 pct of the fluorine contained in the original ore was extracted.

Jan 1, 1974

By Claude W. Sill

In the course of a series of investigations on vanadium deposits of the western United States, the Bureau of Mines collected many hundreds of samples for chemical analysis. As uranium is often associated with these vanadium minerals, they were also analyzed for uranium, which was pound to be absent in a large percentage of the samples. Since the usual methods for determining uranium are laborious and time-consuming it is very desirable to have some simple qualitative test that can be applied prior to a quantitative analysis to determine whether uranium is present or absent and thus save the time and expense of applying the quantitative analysis to the large proportion of samples containing no uranium. To be acceptable, the test should be specific for cranium, sensitive enough to detect small amounts of uranium, and. simple enough to make it worthwhile to apply. The available methods for detecting uranium lacked one or more of the desired characteristics. Eventually, however, a method was worked out that satisfied all the requirements. This method is probably more specific and sensitive than the usual qualitative methods for uranium, and its simplicity and speed of application make it ideal for testing samples prior to quantitative analysis.

Jan 1, 1945

By James C. Cawley

The Bureau of Mines has empirically determined ignition probability versus current for resistive circuits in an 8.3% methane-air atmosphere. Simple ignition probability, defined as the number of ignitions divided by the total number of sparks, was determined, and the corresponding currents were recorded. The experiment was designed to minimize the probability of not observing an ignition that should occur during a series of tests. For resistive circuits in 8.3% methane-air mixtures, the experimental results indicate that ignition was not achieved below 2,000 rnA at 20 V dc, 350 rnA at 30 V dc, 150 rnA at 40 V dc, and 175 rnA at 50 V dc. The simple probability of ignition corresponding to these currents is esti-mated to be, respectively, 1.0 x 10-6, 1.7 x 10-7, 3.0 x 10-7, and 1.0 x 10-5 The ignition mechanism seems to break down below this point, implying that a threshold current value exists below which spark ignition does not occur.

Jan 1, 1987

By Virgil J. Stachura

The Bureau of Mines conducted a series of delayed blasting experiments at a West Virginia contour coal mine that resulted in smoother highwalls. The 17; were smoother due to reduced overbreak and inherently safer A, to reduced likelihood of rockfall. Reduced overbreak was accomplished by an increase in the highwall hole delays, which changed the effective delay pattern geometry and the direction of burden movement. The blast delays in the highwall holes were 50 to 100 ms longer than the mine's nominal design pattern (flat V, 17- by 42-ms surface delays, 200-ms in-the-hole delay). The burden movement was effectively changed from a 45* angle to 90* with respect to the highwall. The results of the blast delay changes were evaluated using terrestrial photogrammetry to generate vertical profiles at regular intervals. This evaluation showed that delay changes produced generally smoother vertical profiles.

Jan 1, 1984

By C. P. Mangelsdorf

When the finely bedded shale frequently encountered over coal seams experiences a separation, the material below the separation must behave like a beam or plate in that it must resist both bending and shear. Be-cause of the weakness in interlaminar shear inherent in such strata, shear deflections that are usually ignored in isotropic beam theory may account for a significant part of the total roof sag. Similarly, when a roof truss is installed in such a roof the upward displacement reducing the sag will have components due to shear as well as bending. Questions asked by mine operators about the installation of roof trusses frequently deal with optimum position, slope, and initial tension of the inclined chords. This Bureau of Mines report examines the effects of those chord parameters on the strain energy of both shear and bending and offers optimum values that will minimize the total strain energy of the immediate roof. Design charts are provided, several design examples are included, and the results are compared with current practice. The effects of in situ stresses are investigated and are shown to be equivalent to an additional load on the beam.

Jan 1, 1988

By V. Castranova, K. Van Dyke

"I. INTRODUCTIONA mechanism which is present in leukocytes and capable of releasing histamine from rabbit platelets was first described by Barbaro and Zvaitler in I966. A soluble mediator between rabbit leukocytes and platelets was also detected by Siraganian and Osier in 1971. This factor was isolated and characterized in 1971 by Benveniste et al. and named platelet activating factor i PAF). It was shown to be released from rabbit basophils through an antigen - IgE-dependent mechanism. The presence of PAF in human leukocytes' and its aggregation and releasing effects on human platelets were also demonstrated. Chemical analysis has shown that PAF is a glycerophospholipid with a choline polar head group. an ester-linked acyl chain at the second carbon and a nonester link at the first carbon.' The structure of the mediator was found to be 1-O-alky1-2-acetyl-sn-glyceryl-3-phosphoryl choline and it has been chemically synthesized.""' A variable portion exists in the alkyl group attached to the first carbon which can have a variety of molecular sizes such as C and C (where Cu is more abundant). Recent work by Pinckard et al."" has shown that there are at least five variations of the alkyl group.PAF has been shown to have a broad range of biological effects. Release of PAF from alveolar macrophages may be important in asthma, allergy, and shock states. In a rabbit model of antigen IgE anaphylaxsis. PAF can induce all of the effects of antigen challenge and. therefore is presumed to be a key mediator in production of anaphylaxsis. In addition to aggregating and degranulating platelets it is a potent chemoattractant."" and causes contraction of guinea pig ileum contraction of lung tissue and enhanced capillary permeability PAF has important effects in the kidney and is also known as the renal hypotensive factor proposed by Blank et al. who found the structure of PAF independently of Benveniste et al.' In producing these responses. PAF acts by a receptor-like mechanism. In platelets. PAF selectively desensitizes itself but not thrombin or collagen. In smooth muscle tissues a similar phenomenon occurs with anaphylatoxin or other stimuli.In vivo. PAF probably acts in concert with other agents in producing its various biological effects. It causes platelets to release histamine serotonin and RCS (rabbit-contractile substance formed from prostaglandins PPG2, PGH2 and TXA2) which contracts rabbit aorta. PAF can cause cells to release SRS-A and leukotriene B."

Jan 1, 1989

The Bureau of Mines has conducted considerable research to improve life support technology for underground mining applications. This proceedings volume presents several new developments that may help increase the chances of mine workers in surviving underground disasters. Several papers address the performance of present self-contained self-rescuers (SCSR's) and provide proposed guidelines for the design and testing of a second-generation SCSR. Improvements In the safety and effectiveness of mine rescue and recovery operations are described, including the design of a low-profile rescue breathing apparatus and a rescue team helmet.

Jan 1, 1987

By Karl C. Dean

The Bureau of Mines stabilized 10 acres of windblown copper mill tailings at McGill, Nev., by a combination chemical-vegetative procedure. Legumes, winter wheat, wheat-grasses, and wild rye were seeded, and the area was subsequently sprayed with a resinous adhesive chemical to stabilize the sands until the vegetation could grow. During the year since treatment, the area has been well stabilized against wind erosion. The established vegetation appears to be capable of self-perpetuation and renewal without irrigation. The cost of stabilizing the area was $135.50 per acre.

Jan 1, 1969

By S. H. Ash

The United States Bureau of Mines has published relatively little on the flooding and unwatering of coal and metal mines. Bulletin 229, Fifty-Nine Coal-Mine Fires, published in 1927, contains several instances of the flooding of mines or sections thereof to extinguish fires but does not describe their unwatering. Report of Investigations 2649, Explosion Hazards Incidental to Unwatering Coal Mines, published in 1924, warned against the possibility of gas accumulations in flooded mines and indicated the precautions to be taken. Report of Investigations 2255, An Unusual Hazard in Reopening Long-Flooded Timbered Metal Mines, published in 1921, told of methane being pocketed and the danger thereof. The flooding of mines originates in many ways. At some mines flooding followed reopening after what was thought to be permanent abandonment; also, explosions have caused some mines to be flooded. Extinguishing fires, accidental encountering of underground streams or flooded old workings, and caves of strata admitting water from underground workings, water-bearing strata, or surface accumulations have also flooded all or parts of mines. Unfortunately, un watering often necessitates much study and causes apprehension largely because experiences in similar situations are not generally known, as few descriptions of successful or unsuccessful methods are available. The job has sometimes been contracted for outside the local management involved and has become a matter of record for the contractor only. As the cost-plus contract system often employed in the past is now known to be expensive, careful managements elect to handle the problem themselves, in line with the general policy of cutting expense where possible. This report describes specific in-stances of successful unwatering by operators.

Jan 1, 1933

By K. C. Dean

During the investigation of the occurrence of manganese deposits in western United States, the Bureau of Mines collected 2-ton samples from three oxide manganese ores in the Columbia and Elberta Mining Districts, Tooelo and Juab Counties, Utah. To determine the amenability of these ores to standard ore-dressing methods: of concentration, extensive laboratory tests were made. The Wildcat property, one of those sampled, is 7 miles east of Fairfield, Tooele County, Utah. The ore is described as a replacement deposit and occurs along fracture and bedding planes of shale and limestone. Experimental work was done on a sample taken from a stockpile at the mouth of the shaft. The Wildcat manganese ore is intermediate in grade (25.7 percent manganese) and contains clay as the principal gangue constituent. A high-grade product was obtained with high recovery of Manganese by simple washing.

Jan 1, 1949

By Charles Vaught

The U.S. Bureau of Mines evaluated the self-contained self-rescuer (SCSR) donning proficiency of 243 miners. These workers were from eight underground coal mines in the eastern United States. The objectives of the study were (1) to gather information on skill levels, since all miners in the study had prior instruction and opportunity to practice donning the apparatus, and (2) to summarize a quality control procedure useful in conducting periodic evaluations of donning proficiency. The sampling procedure used proved to be both reasonable and efficient in gathering information on training effectiveness. It also provided a good statistical base for making informed site-specific decisions regarding SCSR training needs. Results from the observed samples at each of the eight mines indicate a wide variability across sites. The rate at which miners failed to isolate their lungs varied from 3.3 to 40.0 pet. Concomitantly, proficiency rates (miners either performing adequately or demonstrating a perfect 3 + 3 sequence) ranged from 13.3 to 63.3 pet.

Jan 1, 2010

By J. D. Zetterstrom

This report supplements an earlier publication on lightweight aggregates of North and South Dakota.3/ The purpose of the investigation was (1) to study the expansion characteristics of large samples of Dakota clays and shales in a 12-inch by 15-foot rotary kiln; and (2) to improve the laboratory bloating test as a tool for predicting the suitability of samples for the rotary-kiln process. This was done by comparing results of the laboratory and kiln tests.

Jan 1, 1956

Real economic growth for 1988 may fall short of the 3.3% projected by the U.S. Department of Commerce in August 1988 be-cause the summer drought and intense heat in many areas curtailed output more severely than expected. The economy grew at an average annual rate of 3.0% for the first three quarters of the year, slowing in the second and third quarters. Export growth, which occurred even as the dollar edged up com-pared with other industrial country currencies, was an important factor in the expansion. Notable gains were posted in sales of machinery, computers, aircraft, chemicals, and telecommunications equipment. Imports increased, but not as much as exports, and the U.S. trade position was still much improved from that of 1987. Personal consumption expenditures grew slightly faster than the economy as a whole. Purchases of consumer durables showed notable strength in the first half of 1988, but slowed down in the third quarter. [ ] Despite the moderate rise in interest rates, business spending for new plant and equipment also rose and contributed to 1988 gross national product (GNP) growth. Both new business investment and export demand spurred orders for U.S.-made machine tools. Orders for machine tools for the first 8 months of 1988 were almost triple those for the corresponding period in 1987.

Jan 1, 1988

By Samuel A. Goldberg

The Federal Coal Mine Health and Safety Act of 1969 delegated to the Bureau of Mines a yearly program of health inspections. Respirable coal mine dust concentrations are measured by Bureau inspectors. Samples of respirable coal mine dust are weighed to determine dust concentration and then analyzed for ash and quartz content. This paper describes the laboratory procedure for determining the percent quartz in the respirable coal mine dust samples.

Jan 1, 1972

By Q. H. Forbes

"The high injury rand fatality rate in coal mining, as compared with other industries, has caused the mining industry to become more and more interested in accident prevention methods.The prevention of accidents in the mining industry is probably not as simple a problem as it is in other industries, but if the experience of coal mining companies who have taken up the work of accident prevention seriously during recent years means anything, there is little doubt that most mining companies car improve their accident records very materially.Such results can be obtained in practically all instances without adding to production costs. In fact, there is little doubt that a well-organized program of accident prevention Will bring about a 'material production cost reduction due to increased efficiency, lower labor turnover, fewer delays due to accidents, better satisfied workmen, and a direct saving in compensation costs as well as many other items of expense.The more closely a. person is connected with the work of accident prevention, the more he becomes a believer in the value of amity in human relationships and the more he is able to exercise a spirit of toleration, fairness, justness, and helpfulness toward the problems of others, whatever those problems may be. Human nature responds to just these expressions of good willAnother great and invaluable effect of working for safety, is the fact that it is building up in the mind an appreciation of that which is constructive and, conversely, in opposition to that which is destructive In other words; the person who is sincerely striving to prevent accidents because they are destructive, costly, tad injurious, is subconsciously training his mind to look on any proposition from a constructive point of view. Working for accident prevention and safety is about the finest social training any person can have. It does not make a Person a financial Wizard or an executive genius, but it does make for the highest type of citizenship.While humanitarian reasons alone should be sufficient to maze accident prevention work an important factor in every mining organization, there are other reasons as well, since it has been proved conclusively that there can be no efficiency and economy without safety, as somebody pays when safety is lacking. Every safety device pays dividends; every safety application evaded is an assessment and a loss. Dangerous conditions are the most expensive and extravagant conditions in or about a coal mine. The economic gains are of considerable interest to all coal mining companies and this is brought about as before stated--through decreased compensation rates, the reduction of labor turnover, etc."

Dec 1, 1930