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By Clark F. Grain

The monoclinic to tetragonal inversion of zirconium dioxide was studied by single-crystal X-ray methods, high-temperature X-ray diffractometry, and differential thermal analysis. The unusual features of the inversion, such as no definite transition Lperature, hysteresis, and athermal kinetics, were confirmed for powders who mean crystallite size was greater than 1,000 A. Samples of mean crystallite size below 1,000 A displayed classical kinetics, obeying a logarithmic rate law. A detailed mechanism based on Ubbelohde's theory of continuous phase transformations was proposed which is consistent with all the experimental facts.

Jan 1, 1965

By E. C. Tarpley

The Federal Bureau of Mines has studied solvent extraction as a means of concentrating the mineral components in coal. Solubilities of a number of American coals were determined using abietic acid as a solvent. The effect of rank on solubility was investigated, and maximum solubility was found with coals of intermediate rank. Vitrinite is the most soluble petrographic component; fusinite, micrinitc, and exinite are nearly insoluble. Spore exines also have a low solubility. Abietic acid is a hydrogen donor and reduces pyrite to ferrous sulfide. Mild hydrogenation of high-molecular-weight fragments of the coal structure to those of lower molecular-weight probably contributes to the solvent action. Even where solubility of the coal substance exceeds 90 percent, contamination of the mineral matter with coal makes identification of the mineral components difficult. Further separation might be possible by the application of float and sink techniques to the residue. INTRODUCTION Work n the solvent extraction of coal is conducted to recover commercially useful products and to characterize coal;. and obtain information on their structure. Some coals, particularly those of low rank, contain waxes, resins, and humic acids which can be removed by solvent extraction and find varied industrial uses. In World War II, solvent extraction of coal was conducted on a commercial scale in Germany to obtain a low-ash feed material for hydrogenation and to produce electrodes carbon for the aluminum industry.4 5/

Jan 1, 1960

By Jacqueline A. McClaskey

The U.S. Bureau of Mines 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 Bureau'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 U.S. Bureau of Mines 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

By G. L. Neumann

In October 1949 the College Park Branch of the Mining Division instituted a survey of the New England pegmatites. Many of the New England pegmatite deposits were superficially examined, and the Bumpus quarry in Albany, Oxford County, Maine (see fig. 1), was selected for a diamond-drill exploratory-development project to supply information for developing more economical mining methods and no increasing production of beryl and other scarce minerals associated with pegmatitic intrusives. The Bumpus quarry has been mined intermittently by three operators since it was opened in 1927. At the time of drilling, the vein or dike (see figs. 2 and 3) had been mined to a depth of 60 feet for a strike length of 280 feet. The dike averages 40 feet in thickness and dips 50 degrees southeast. The Bureau of Mines drilled seven diamond-drill holes between September 27 and November 27, 1950. These holes showed that the dike persists for at least 350 feet to the east and probably 200 foot to the west of the present excavation. The drilling also indicated that the dip, as exposed at the surface, continued unchanged at 500 to a depth of at least 50 foot below the pit. The dike was not delineated, although it fingered out as pegmatite interbanded with Granite, diorite, and gneiss in diamond-drill hole B-4, approximately 250 feet west of the pit. Further drilling will be necessary to find the extent of this pegmatite dike and to determine the safest and most economic mining system.

Jan 1, 1952

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

By R. Karl Zipf

A fatal explosion in a sealed area at the Sago Mine in 2006 prompted researchers and regulators in the United States to re-examine the requirements for explosion-resistant mine seals. Seals are used in underground coal mines to isolate abandoned mining areas from active workings. Prior to the Sago disaster, mining regulations required seals to withstand a 140 kPa explosion pressure. Recent research at the National Institute for Occupational Safety and Health (NIOSH)Pittsburgh Research Laboratory showed that pressures from explosions can far exceed this pressure. U.S. mining regulations now require much stronger seals. Current research focuses on understanding the science, engineering and management of sealed areas of coal mines. Scientific efforts seek understanding of how explosive methane-air mixtures accumulate using measurements and models of the sealed area atmosphere. Additional scientific efforts aim to understand the explosion pressures that can develop using a combination of numerical modeling and experiments. Engineering efforts aim to produce design guidelines for seals that can resist the new higher pressure design criteria. NIOSH researchers are also developing guidance for monitoring of sealed area atmospheres and inertization of potentially explosive gas mixtures within sealed areas. This paper seeks to encourage scientific discussion among international peers since preventing explosions within sealed areas is of interest to underground coal operators and regulators.

Jan 1, 2009

By Kenneth Lipman

Auxiliary equipment was assembled around a purchased oscillograph to permit observation of the current and voltage characteristics of low-energy, capacitance-discharge sparks having durations of at least 10 mµ-sec. Circuit details of the assembled apparatus, performance characteristics of the complete system, and some preliminary data from representative self-initiated sparks are given in this report. INTRODUCTION One of the subjects of continuing research by the Federal Bureau of Mines Division of Explosives Technology is the ignition of explosive-gas mixtures by means of low-energy capacitance sparks. Quite early in these investigations it was recognized that understanding the gas-ignition phenomena would be facilitated by detailed information about the performance of the ignition source (spark) under the actual conditions of interest; however, the sparks of practical interest are nonrepetitive transient phenomena whose duration could reasonably be estimated to be in the time range of 1 mµsec. to 1 µsec. As such, the only feasible method of obtaining detailed information was and is oscillographic representation of the pertinent current and voltage transients. It was not until 1947 that a suitable, commercial, dual-channel oscillograph could be obtained as the basic instrument for these studies; the instrument specified in 1947 was delivered in 1950. This paper describes the auxiliary

Jan 1, 1959

The principal activities of the Bureau of Mines Pittsburgh Mining and Safety Research Center during fiscal year 1971 (July 1, 1970, to June 30, 1971) are reviewed in part 1 of this paper. Part 2 summarizes publications during fiscal year 1971.

Jan 1, 1974

By Ludwig Schmidt

[The use of vapor-tight tanks has proved so effective in reducing the evaporation losses of petroleum that today practically all operators are using this typo of equipment. It has boon shown, however, that vapor-tight tanks should be supplemented with additional measures which will further reduce evaporation. Probably the most effective use of the supplemental measures are found on the small producing leases where the breathing losses from vapor-tight stock tanks materially affect the volume and gravity of the stored oil. The breathing loss from a vapor-tight stock tank that is filled and emptied daily is a negligible quantity. Also, the filling loss, which on the average varies between 0.1 and 0.2 per cent, usually is not of a sufficient quantity to affect materially the value of the crude. However, the combined breathing and filling losses from a vapor-tight tank requiring several days to fill are of sufficient importance to warrant the use of measures in addition to the vapor-tight tanks. The breathing losses are caused by atmospheric variations. Probably the greatest are the changes in atmospheric temperature which cause changes in temperature of the vapors in the tank. During the day, as the temperature increases, the gasoline-saturated vapors in the tank expand and are forced out into the atmosphere. At night the vapors are cooled and contract, drawing into the tank fresh air, which becomes saturated with gasoline vapor and is forced out of the tank during the following day. In Addition to the maximum and minimums temperature variations there are many smaller variations throughout a twenty-four period caused by showers, clouds, winds, and other atmospheric conditions which likewise cause the tank to breathe. The two mist common measures used by lease operators for reducing breathing losses in vapor-tight tanks are, first, operating; lease tanks under pressure, and second, the use of light colored paints anti tank houses. In this report these two methods are discussed together with their adaptability to lease operation. Results of experimental observations are given which show the reduction of evaporation looses where these supplemental measures have been used.]

Jan 1, 1927

By R. P. Adams, R. A. Beall

The Bureau of Mines developed a method to melt and cast specimens of hafnium- carbon alloy and studied their properties . A rotating - ladle vacuum or inert atmosphere arc furnace was designed , special electrodes and molds were developed , and operating procedures were worked out for casting small shapes . The cast specimens were evaluated according to their carbon content for melting point , density , microhardness , electrical resistivity , and oxidation resistance . Lattice dimensions were determined , and metallographic specimens were prepared . Photomicrographs were taken of specimens containing 2.72 , 5.50 , 6.47 , 9.97 , 12.8 , and 15.7 weight - percent carbon , and their grain structures were compared .

Jan 1, 1963

By John J. Sammarco

Computer-related accidents have caused injuries and fatalities in numerous applications. Normal Accident Theory (NAT) explains that these accidents are inevitable because of system complexity. Complex systems, such as computer-based systems, are highly interconnected, highly interactive, and tightly coupled. We do not have a scientific methodology to identify and quantify these complexities; specifically, NAT has not been operationalized for computer-based systems. Our research addressed this by operationalizing NAT for the system requirements of safety-related computer systems. It was theorized that there are two types of system complexity: external and internal. External complexity was characterized by three variables: system predictability, observability, and usability -the dependent variables; internal complexity was characterized by modeling system requirements with Software Cost Reduction dependency graphs, then quantifying model attributes using 15 graphtheoretical metrics the independent variables. Dependent variable data were obtained by having 32 subjects run simulations of our research test vehicle: the light control system (LCS). The LCS simulation tests used a cross-over design. Subject perceptions of these simulations were obtained by using a questionnaire. Canonical correlation analysis and structure correlations were used to test hypotheses 1 to 3 - the dependent variables predictability, observability, and usability do not correlate with the NAT complexity metrics. Five of 15 metrics proposed for NAT complexity correlated with the dependent data. These 5 metrics had structure correlations exceeding 0.25, standard errors < 0.10, and a 95% confidence interval. Therefore, the null hypotheses were rejected. A Wilcoxon signed ranks test was used to test hypotheses 4 to 6 - increasing NAT complexity increases system predictability, observability, and usability. The results showed that the dependent variables decreased as complexity increased. Therefore, null hypotheses 4 to 6 were rejected. Lastly, this work is a step forward to operationalize NAT for safety-related computer systems; however, limitations exist. Opportunities addressing these limitations and advancing NAT were identified. Lastly, the major contribution of this work is fundamental to scientific research - to gain knowledge through the discovery of relationship between the variables of interest. Specifically, NAT has been advanced by defining and quantifying complexity measures, and showing their inverse relationship to system predictability, observability, and usability.

By A. D. Garman

This paper presents one of a series of digests of foreign mining legislation and court decisions which is being prepared in advance of a general report relative to the right of American citizens to explore for minerals and to own and operate mines in various foreign countries . This interpretation of the laws of Uruguay has been prepared from the best available information in Washington, but is released subject to correction and amplification , if necessary , by the proper American diplomatic and consular officers to whom it is being referred through the courtesy of the Department of State .

Sep 1, 1930

By L. C. George

Addition of an acid waste to an alkaline cyanide waste was investigated for five different combinations of electroplating wastes. At the optimum final pH values of the mixtures, metals and cyanides were almost quantita¬tively precipitated. No evolution of hydrogen cyanide was detected by a few additional processing steps, significant amounts of variable metals were recovered for recycling the waste-plus-Waste step is attractive because no reagents are required, metals arc concentrated, and a relatively harmless effluent that meets most water quality Standards for cyanide content is produced.

Jan 1, 1970

By G. W. Weems

The Bureau of Mines combined preconcentrating techniques and mass spectrometry to develop a parts-per-billion general analysis of impurities in helium. The impurities are preconcentrated using a Bureau trace-impurity analyzer; 35-mm Hg pressure of helium is left in the concentration trap to sweep the impurities into the mass spectrometry and provide a 10-mm Hg sample pressure.

Jan 1, 1966

By J. E. Murphy

The Bureau of Mines developed a hydrometallurgical method for recovering mercury metal from mercury sulfide concentrates. Sulfide flotation concentrate from the McDermitt Mine was leached in a cupric chloride solution at 80° C. The redox potential of the solution was maintained at 850 mV during leaching by chlorine sparging. Mercury extractions exceeded 99 pct in 3 h of leaching. After leaching, the pH of the solu-tion was increased from 1 to 4.5 to precipitate copper as atacamite. The pregnant solution typically containing 100 giL Hg was sent to elec-trolysis to produce high-purity mercury metal and chlorine for recycle. In a 200-A electrolytic cell operated for 24 h, current efficiency was 99 pct and the energy requirement was 0.9 kW·h/lb of mercury produced. Mercury removal from the waste stream was also investigated. Iron or zinc cementation, sulfide precipitation with H2S, and activated carbon adsorption all decreased the mercury concentration from 10 giL to 0.01 mglL, which is less than the Environmental Protection Agency limit on wastewater of 0.02 mg/L.

Jan 1, 1987

By Carl Belser

In 1925 the Park Utah Consolidated Mines Co., after several years of experimental work, installed a system for signalling from cages which has been operating efficiently and with low upkeep costs for the post 19 years. The system was adopted for a large western metal mine but was later abandoned be arse of the constantly shifting shaft alinement. Recently the system has been studied and probably will be put into service at two other large mines. One of the principal reasons wry the system has not boon adopted more widely has been the lack of adequate details both as to the desirability of having such a system and as to its construction and operation. Previous signaling, systems contained undesirable features, such as charged bare wires extending the full length of the shaft. Under the direction of O. N. Friendly, then general superintendent of the Judge Mining & Smelting Co., the present system, entailing the use of a samll current at low voltage, was gradually developed. Many of the refinements in the system wore contributed by Leonard Wilson, consulting electrical engineer, Salt Lake City, Utah.

Jan 1, 1945

By Michael J. Magyar

This report contains a cost estimate of the Bureau of Mines process for dewatering Alaskan placer effluent streams with polyethylene oxide (PEO). In this process effluent slurry is withdrawn from the placer plant pond system after a primary settling stage. A dilute PEO solution is injected into the slurry line to flocculate the fine, suspended solids. The flocculated solids are dewatered on a stationary screen. Clarified water is returned to the placer operation or discharged, while the 35 percent solids waste is pumped back into the mine cut. Cost estimates are presented for dewatering plants processing 1,000 gallons per minute of effluent slurry at three representative turbidity levels. Both the placer and the dewatering plants operate on the same 1-shift-per-day, 6-day-per-week schedule for the 100-day Alaskan operating season. Estimated fixed capital costs for these plants processing placer with effluent turbidities of 1,000, 3,000, and 5,000 nephelometric turbidity units (NTU) are approximately $29,000, $31,000, and $34,000, respectively, on a fourth quarter 1986 basis. Operating costs are estimated to be $0.34, $0.37, and $0.40 per thousand gallons of effluent slurry.

Jan 1, 1987

Consumption and intensity of use trends for 12 metals, by industrial end use, were estimated for 1972 through 1982 by the Bureau of Mines and U.S. Department of Commerce. The trends were then forecast through 1993 using standard statistical methods. The intensity of use measure selected is the quantity of metal consumed per constant dollar output of a specific industrial sector. The metals studied were aluminum, chromium, cobalt, copper, lead, manganese, nickel, the platinum-group metals, tin, titanium, tungsten, and zinc. Average annual growth rates for the following 4 of the 12 metals increased from 1972 to 1982 as follows: aluminum, 1.00%; platinum-group metals (consisting of platinum, palladium, and iridium), 8.83%; titanium, 7.82%; and tungsten, 6.09%. Consumption for the remaining eight metals decreased at average annual rates ranging from 0.58% (copper) to 5.37% (manganese).

Jan 1, 1986

Most laboratory sealant studies were carried out in 2.0 inch I.D. Plexiglas tubes of 9.0 inches height containing 4.0 to 4.5 inches reconstructed soil from an 0-8 or 8-16 inch soil horizon at the Lanse site. (When soil was used from the Kato site, the top soil horizon was approximately 0-4 inches. The 4-8 inch horizon was somewhat comparable to the Lanse 8-16 inch horizon.) A 20 mesh Saran or steel screen was placed over the rubber stopper with a bottom drain to a 100 ml measuring cylinder. In some earlier experiments a 1/2 inch bed of 1/4 inch pea-gravel was then added, but in later experiments this was eliminated as it showed no particular utility. Field soil samples collected by a shovel were stored in sealed containers and sieved through a 4 mesh screen just before use. (Moisture content was typically about 25% for A horizon soil and about 20% for B horizon soil.) The sieved soil minus roots was then added in increments of about 1 1/4 inches. Compaction was effected by dropping a weighted ramrod (1-7/8 inches O.D,) five times from a height of two inches. If about twenty tamps were used or if the soil columns were rapped vigorously while water-logged, compaction was high with no detectable percolation. Freezing such samples would then usually cause very slow percolation, e.g. 1-2 ml/day. Using this as a standard procedure, percolation flows were usually stablized after two to three days to rates of about 100 to 200 ml/hour. Percolate was recycled carefully to minimize disturbance of the soil surface. When percolation flows were about 100 to 200 ml/hour, various additives (sealants) were introduced to the moist column in two to three increments to maintain a slight head. Additive concentrations were usually 2-1/2% with some at 5% in earlier experiments. Typical use of 40 ml of 2-1/2% additive corresponds to 4400 lbs/acre. When no more additive was present as supernatent liquid, water washes of about 15 ml were then used several times followed by special additives as needed. More water washes were then used to maintain a head of about 1/2 inch. Percolate was collected in 100 ml cylinders to measure percolation rates in ml/hr. Turbid percolate was evaporated to determine amount of eluted latex. Percolate was sometimes checked for pH by Pan-pH Indicator Paper9,10 reading in 0.5 units. Surface tension measurements were sometimes made by a DuNouy tensiometer10 in experiments using a surfactant for pretreatment.

Jan 1, 1972

By Claire C. Caruso, John M. Russo, Jennifer M. Schmit, Robert B. Dick, Edward M. Hitchcock

PURPOSE This report provides an integrative review of 52 recently published research reports that examine the associations between long working hours and illnesses, injuries, health behaviors, and performance. The report is restricted to a description of the findings and methods and is not intended as an exhaustive discussion of all important issues related to long working hours. Findings and methods are summarized as reported by the original authors, and the study methods are not critically evaluated for quality. SUMMARY In 16 of 22 studies addressing general health effects, overtime was associated with poorer perceived general health, increased injury rates, more illnesses, or increased mortality. One meta-analysis of long work hours suggested a possible weak relationship with preterm birth. Overtime was associated with unhealthy weight gain in two studies, increased alcohol use in two of three studies, increased smoking in one of two studies, and poorer neuropsychological test performance in one study. Some reports did not support this trend, finding no relationship between long work hours and leisure-time physical activity (two of three studies) and no relationship with drug abuse (one study). A pattern of deteriorating performance on psycho physiological tests as well as injuries while working long hours was observed across study findings, particularly with very long shifts and when 12-hour shifts combined with more than 40 hours of work a week. Four studies that focused on effects during extended shifts reported that the9thto 12th hours of work were associated with feelings of decreased alertness and increased fatigue, lower cognitive function, declines in vigilance on task measures, and increased injuries. Two studies examining physicians who worked very long shifts reported deterioration on various measures of cognitive performance. When 12-hour shifts combined with other work-related demands, a pattern of more adverse findings was detected across studies. Six studies examining 12-hour shifts combined with more than 40 hours of work per week reported increases in health complaints, deterioration in performance, or slower pace of work. Two studies com-paring 8- and 12-hour schedules during day and night shifts reported that 12-hour night shifts were associated with more physical fatigue, smoking, or alcohol use. Two studies examining start times for 12-hour shifts reported that decrements in alertness or more health complaints were associated with early 6:00 a.m. start times. One study examining 12-hour shifts in hot work environments reported a slower pace of work as compared with shorter shifts. Another study examining high workloads during 12-hour shifts showed increased discomfort and deterioration in performance as compared with shorter shifts. More definitive statements about differences between 8-hour and 12-hour shifts are difficult because of the inconsistencies in the types of work schedules examined across studies. Work schedules differed by the time of day (i.e., day, evening, night), fixed versus rotating schedules, speed of rotation, direction of rotation, number of hours worked per week, number of consecutive days worked, number of rest days, and number of weekends off. All of these factors could have interacted with overtime and influenced study results. Also, some studies did not report how many hours participants worked per week or other details about the work shifts, which complicated the assessment of their results. The many

Jan 4, 2004