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By W. L. O'Brien, E. A. Rowe

Electrorefined vanadium with additions of up to 5 percent by weight of yttrium, cerium , lanthanum , praseodymium, neodymium, and samarium was melted to ingots in a nonconsumable electrode arc in a helium atmosphere . The ingots were rolled into strips and evaluated for the effect of the alloying elements on hardness , tensile strength , ductility , recrystallization temperature , and microstructure . Except for samarium , average additions of alloying elements of 1 to 2 weight - percent resulted in the retention of 0.12 to 1.05 weight - percent in the alloys and reduced the ultimate tensile strength from about 48,000 to approximately 30,600 psi . The corresponding yield stress (0.2 percent offset ) was reduced from about 40,700 to approximately 20 , 200 psi . Diamond pyramid hardness (DPH) was reduced from 117 to an average of 62 kg /mm² . Increased malleability at room temperature resulted with yttrium and all rare - earth- metal additions , except samarium , particularly with more than 0.25 weight - percent additions . Decreasing oxygen contents corresponded with the changes noted in the mechanical properties of the alloys . The recrystallization temperature of electrorefined vanadium was reduced from approximately 950 ° to 800 ° C. Yttrium or a rare- earth metal content , except samarium , in excess of 0.1 weight - percent in vanadium produced a second phase suggestive of an eutectic which indicated a possible maximum solubility of less than 0.1 weight - percent for both room and elevated temperatures .

Jan 1, 1964

By P. V. Fillo

This paper describes Mohave Mining and Milling Co. methods of mining and milling manganese ore in Arizona. It is one of a series of publications prepared by the Bureau of Mines on methods and costs in various mining districts in the United States. Production of manganese ore, as such, in Arizona began in 1915. Before this time manganiferous ores had been mined primarily for silver content and used as a smelter flux. From 1916 to 1918 approximately 69,000 long tons of manganese and mangsniferous ores were mined. After World War I production dropped to almost nothing until World War II, during which period more than 24,000 long tons were produced. A lull in mangonese mining occurred after World War II, having production rates of only a few hundred tons annually through 1952.

Jan 1, 1963

By J. J. Hoeppner

Accurate determination of moisture in coals of various ranks has long been a subject of intensive investigation. Excellent reviews of methods developed over many years are given by Brown (9)4/ and, with experimental comparisons, by Goodman, Gomez, and Parry (11). As pointed out in these and other writings, one of the principal difficulties in assigning absolute merit to one or another procedure is the multiplicity of conditions under which water may exist in coal and the difficulties involved in obtaining sharp separation and distinction between these classes. Gauger (10) states: Water recoverable from coal is obtained from the following sources: (1) Decomposition of organic molecules (sometimes called combined water), (2) surface adsorbed water, (3) capillary condensed water, (4) dissolved water, and (5) water of hydration of inorganic constituents of the coal.

Jan 1, 1956

By Erie C. Donaldson

Gas-displacement tests were made in Berea Sandstone and Arbuckle Lime-stone cores to determine the relative permeabilities to gas, oil, and water for two-and three-phase dynamic systems. Three-phase relative permeabilities were obtained by displacing oil and water from the core with gas and measuring the flow rates of the three fluids simultaneously. It was found that relative permeabilities to fluids in a porous medium are affected by the saturation distributions of other fluids in the medium as well as by their own saturation distributions.

Jan 1, 1966

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

By T. T. Read, T. L. Joseph, F. H. Royster

In a preliminary study of the beneficiation of iron ores conducted by the Bureau of Mines, one of the authors (T. T. Read) found it necessary to ascertain, if possible, how much effect a decrease in the silica content of an iron ore has upon the cost of making pig iron from the ore. In the beneficiation of iron ores the most important impurity to be removed is usually silica, and the amount that can be expended on a beneficiation process to reduce the silica content of the ore is obviously determined by the amount of increase in the value of the ore after beneficiation. The price that can actually be obtained for a beneficiated ore is, of course, a matter of negotiation between the seller and the buyer, but since the relative value of different grades of iron ore must be chiefly based upon the cost of making pig iron from them, an approximation as to the effect which decrease in the silica content of ore has upon the cost of snaking pig iron is an important guide in estimating what probable average gain will result from subjecting an ore to a beneficiation process. A search of the literature failed to reveal any detailed statement on this important topic, but fortunately the data are at hand to permit making an approximate calculation of the probable effect. For the purpose of the calculation assume three iron ores with the following composition (natural):

Jan 1, 1924

By Gordon E. Fletcher

This Bureau of Mines report outlines the atomic absorption analysis of oilfield brines for barium, calcium, copper, iron, lead lithium, magnesium, manganese, potassium, sodium, strontium, and zinc, using the method of additions. The advantages of using atomic absorption are discussed. The method of additions was chosen to overcome large matrix interferences usually found in brines; techniques of overcoming chemical, ionization, and background interferences are also described. The method was used to analyze several hundred oilfield brines and found to be rapid and reasonably accurate. A solvent extraction method was used to concentrate lead, copper, zinc, and iron in low-level samples.

Jan 1, 1974

By Scott W. Hazen

In recent years many mining companies have recognized that their chance for continued economic survival depends on the adaptation of technological advances in their operations. Increased productivity through new developments in mining methods and improvements in equipment has made mining and processing of lower grade ores possible. Cost analysis has produced accurate data on the costs for development, production, and processing of ore. All of these changes and cost studies have shown the necessity for increased accuracy in determining the grade of ore. Methods of estimating grade in a mineral deposit have not kept pace with the technological advances in the other areas. The same methods are in use today as in the past. Experience and judgment are major criteria of accuracy and the results are highly subjective. In 1953, as part of its research program to develop a better understanding of fundamentals of mining technology, the Federal Bureau of Mines began a sampling method research project at its Denver Mining Research Center. The basic objective of the project is to investigate sampling methods and to study the adaptation of the techniques of statistical analysis to mine sampling.

Jan 1, 1961

By T. J. Williams

Researchers at the U.S. Bureau of Mines monitored rock mass response to mining of an experimental underhand longwall stope in Hecla Mining Co.'s LUCKY Friday Mine, Mullan, ID. This stope design, the Lucky Friday underhand longwall (LFUL), was proposed as a means of controlling rock bursting while also allowing increased mechanization of mining operations. Instruments were specifically manufactured to monitor three geomechanical factors (backfill performance, ramp stability, and rock mass response) that directly affect the success of stope design. Despite considerable difficulties with instrument installation and survival in the harsh mine environment, especially within the stope fill, sufficient information was collected to suggest that the LFUL method was successful in achieving project goals. This conclusion, in addition to favorable economic and operational evidence, led the mine to adopt the method throughout the mine. Indeed, this study and mining experience suggest that underhand longwall mining could be considered a feasible mining method for rock-burst-prone ground throughout the Coeur d'Alene District. Further Reports of Investigations (RI) in this series present in-depth analyses of the effects of backfill on rock bursting and calibration of a stope numerical model.

Jan 1, 2010

By Oliver W. Keener

This paper describing the methods and costs of mining at the Hartley-Grantham mine of the Century Zinc Co. in the Tri-State Lead and Zinc district is one of a series being prepared by the United States Bureau of Mines can mining practices, methods, and costs in the various mining districts of the United States. LOCATION, HISTORY, AND GEOLOGY The Hartley-Grantham Mine is located just outside the city limits of Baxter Springs, Kans., as shown in Figure 1. A plan of the mine is given in Figure 2, and Figure is a cross section through A - A of Figure 2.

Jan 1, 1930

By E. B. Kester

In the commercial evaluation of coal tars, a distillation analysis properly carried out is of considerable importance. Close attention must be given to this operation in order to obtain consistent results and to secure the minimum decomposition of the tar compounds, Which in Many cases are sensitive to undue heat effects. Low-temperature tars in particular contain compounds of this nature, while in the case of tars produced at high temperatures the large proportion of pitch present has an adverse influence during a distillation. If excessive cracking takes place, the composition of the distillate will naturally vary from the normal, with the result that all the analytical criteria subsequently obtained are affected. Where tars, produced over wide ranges of carbonization temperatures are investigated as in the survey of gas, coke, and by-product making properties of American coals now being conducted at the United States Bureau of Mines Pittsburgh Experiment Station, the method of distillation must necessarily be the same for all of the tars studied. Also, it mast function equally well for both low and high temperature tar permit accurate fractionation, and reduce adventitious decomposition to a minimum. The authors are aware that certain types of distillation analysis which do not meet the above requirements may give results comparable with those of the large stills of a by-product coke-plant where one type of tar is produced. These may be simpler and shorter and entirely suitable for control work, but at the same time have little value in a fundamental investigation.

Jan 1, 1932

The objectives of this research were to examine and to laboratory performance of several brands of rigid urethane een brands, produced by 13 manufacturers, were examined. was performed in a laboratory under controlled conditions. document the foam. Eight-All testing Preliminary laboratory tests included flame spread evaluations, flame penetration, ignition temperatures, air permeability, and adhesion. Having established arbitrary cutoff values, the original 18 candidates were narrowed to 8. More specialized tests followed. The effects of water immersion and dry aging on flame spread performance and other physical properties were then examined. This Bureau of Mines report was written to provide information for those concerned with using rigid urethane foam as a sealant. Its intent is to describe the various laboratory evaluations performed and to delineate the performance of each candidate. This report neither promotes nor discourages the use of rigid urethane foams. It presents results that will enable those responsible for using or enforcing the use of rigid urethane foams in underground mines to make informed decisions.

Jan 1, 1985

By E. B. Kester

In the commercial evaluation of coal tars, a distillation analysis properly carried out is of considerable importance. Close attention must be given to this operation in order to obtain consistent results and to secure the minimum decomposition of the tar compounds, which in many cases are sensitive to undue heat effects. Low-temperature tars in particular contain compounds of this nature, while in the case of tars produced at high temperatures the large proportion of pitch present has an adverse influence during a distillation. If excessive cracking takes place, the composition of the distillate will naturally vary from the normal, with the result that all the analytical criteria subsequently obtained are affected. Where tars, produced over vide ranges of carbonization temperatures are investigated as in the survey of gas, coke, and by-product making properties of American coals nor being conducted at the United States Bureau of Mines Pittsburgh Experiment Station, the method of distillation must necessarily be the sane for all of the tars studied. Also, it must function equally well for both low and high temperature tar, permit accurate fractionation, and reduce adventitious decomposition to a minimum.

Jan 1, 1932

By J. E. Tiffany, N. A. Tolch

The Pittsburgh Experiment Station has made a survey of the properties and characteristics of the brands of fuse manufactured in the United States ; 25 samples were procured from 4 manufacturers representing the different brands offered on the market when the investigation was begun . It is believed that the field was completely covered except for special fuse made to order for a particular job .

Jun 1, 1934

By Fred L. Bishop

This paper describing the methods employed in the purchasing and supply departments of the Miami Copper Co., Miami, Ariz., is one of a series being prepared for and published by the United States Bureau of Mines on office practice in mining operations. GENERAL DESCRIPTION The Miami Copper Co.'s plant is located about 1 mile from the town of Miami, in the Globe-Miami Mining District, Gila County, Ariz. The property consists of a complete mining plant, concentrator, high-pressure steam power plant, and many other attendant structures. In normal times the company employs about 1,500 men, and mines and mills about 6,000,000 tons of ore annually.

Jan 1, 1932

By Henry M. Harris, Hal J. Kelly

Electrical dewatering tests are described in which the laboratory cells were designed for continuous operation using an endless metal belt as the anode . The test slurries were dilute , containing from 2.5 to 14.4 percent solids (specific gravity of 1.02 to 1.10 ) that were all minus 8 microns in size . Recovery of the solids of low water content was the practical objective of the investigation . Process variables evaluated and reported are : The effect of feed rate , amount of electrolyte , samples from different sources , and the use of two cells in series . These variables are evaluated on the basis of yield of clay per kilowatt - hour , recovery , and the amount of solids in the deposited clay . Recovery , yield , and solid content of the belt anode product are interdependent , and changes that will improve one of these characteristics often are accomplished at the expense of the others . Tests in which recoveries range from 50 to 60 percent usually result in yields of 8 to 9 kilograms (kg ) of dry clay per kilowatt- hour (kwhr ) . Under these conditions , the solid content of the deposited clay approximates 50 percent . One test sample , composed of kaolinite , showed very high yield , 13 to 16 kg per kwhr ; high recovery , 53 to 58 percent ; and 52 to 54 percent solids in the cake .

Jan 1, 1964

By M. J. Ferrante

Relative enthalpies of CuBr from 298.15 to 1,301 K were measured at the Bureau of Mines to provide thermodynamic data needed for the advancement of mineral technology. The temperatures of transition were measured by differential scanning calorimetry (DSC) and the standard enthalpies of transition[ (IlH~r) by drop calorimetry. The combined results gave reversible transitions at 657 K with llH~r= 1.10 kcal/mol, at 741 K with lm~r == 0.51 kcal/mol, and at 759 K with an enthalpy of fusion (AH~) of 1.22 kcal/moL ] An anomalous increase in heat capacity preceded the first crystal transition at 657 K. Tabulated values are listed for the standard relative enthalpy, heat capacity, entropy, and Gibbs energy function from 298.15 to 1,500 K. Standard relative enthalpies are also given in equation form and combined with thermodynamic data from the literature to derive values of standard enthalpies of formation and Gibbs energies of formation.

Jan 1, 1984

By Oliver Bowles

"Properties and Uses.Iceland spar is a name given to a pure crystallized form of calcite (CaCo3) which is sufficiently transparent and free of defects to be used in the manufacture of optical instruments. While the actual requirements are small, the degree of purity and physical perfection demanded renders it somewhat difficult to obtain suitable material.The properties of value in Iceland spar are its transparency combined with double refraction. It is used in the manufacture of polarizing microscopes, saccharimeters, colorimeters and photometers. Its most important use is in the manufacture of Nicol prisms, which constitute an essential part of every polarizing microscope. The principle governing the construction of the Nicol prism is as follows:Ordinary light in passing through a crystal of calcite is resolved into two rays of plane polarized light vibrating in planes at right angles to each other and having different indices of refraction. Thus the two rays follow different paths through the crystal. The prism of Iceland spar is cut diagonally and cemented together again with a transparent cement having an index of refraction intermediate between the two rays passing through the prism. Canada balsam is employed for this purpose. The prism is cut at such an angle that the ray having the greatest index of refraction meets the surface of the balsam at an angle greater than the angle of total reflection, and it is thus deflected to the side of the prism, while the second ray passes through. Thus one of the rays is eliminated and polarized light vibrating in a single plane is obtained."

Apr 1, 1920

By V. E. Homme

Low- and high-temperature reduction techniques were employed by the Bureau of Mines in study of conditions favorable to the formation of massive titanium crystals. '1,1,2 low-temperature method, feeding molten sodium to solidified titanium lower chloride-sodium chloride, produced higher quality and high quantity crystalline metal. The percentage of crystalline titanium was increased with increasing reactor diameter, melt depth, and titanium dichloride concentration. The high-temperature technique, feed molten sodium to melts above 8000 C, producing needle-type crystals of lower quality and with less consistent results than the low-temperature method. Layers of titanium foil, sponge, fine needles, wool, and crusts of sin-tered granules were formed during the earl, -art of the low-temperature reduction, and massive crystals were produced beneath this barrier in the latter part of the reduction. Crystalline titanium having an average hardness of Bhn 76 and representing 58 percent of the total titanium was obtained. Lamellar crystals up to 1 1/2 inches long with a hardness as low as Bhn 54 were also produced. A second-stage reduction for reclaiming titanium from offgrade sponge is described. Titanium produced by this method was comparable in quality to that from sodium reduction of titanium tetrachloride.

Jan 1, 1966

By Carl Rampacek

The conversion of dilute sulfur dioxide gas into sulfuric acid by autoxidation in mechanical cells of the flotation or gas absorber types was investigated. Bench-scale tests were made with sulfur dioxide-air mixtures to determine the influence of several factors on autoxidation of sulfur dioxide, using iron and manganese salts as catalysts. The laboratory investigation subsequently was extended to pilot plant acid-making tests, using a modified turbomixer gas absorber having a 12-inch-diameter impeller. Sulfur dioxide gas was produced for the tests by roasting pyrite in a fluidized-bed reactor. In the better tests, made with manganese sulfate as the catalyst, the equivalent of 1,000 pounds of anhydrous H2SO4 was produced per 24 hours as a 10-percent solution; power consumption was 0.2 kwhr per pound of equivalent anhydrous acid synthesized. The batch and continuous tests demonstrated the technical feasibility of producing dilute sulfuric acid by autoxidation of sulfur dioxide gas in mechanical cells when converting pyrite roaster or waste smelter gases.

Jan 1, 1963