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By Mary F. Koehler

Interoxidic compounds, such as vanadates, have not been studied extensively in the field of thermodynamics. This is a report of three vanadates of sodium--metavanadate, pyrovanadate, and orthovanadate. Vanadates of other metals will be considered in future reports. The heats of formation at 298.15° K. of the three sodium vanadates (both from the oxides and from the elements) were derived from the results of sodium hydroxide solution calorimetry. Free energies of formation were obtained by combining heat and entropy values. The results support the conclusion that the three sodium vanadates were stable with respect to all possible decompositions in which vanadium retains its pentavalency.

Jan 1, 1960

By W. A. Haley

This is the second of a series of publications that describes the progress of mechanical longwall coal mining in the United States in which a German coal planer was employed.3/ Details of the equipment, a description of its operation, and the results obtained in mining the experimental panel were published in the preceding report. Experimental mining with the planer in the first panel showed an improvement in performance over conventional mining methods at the coal company's Stotesbury 11 mine. The work, which was begun on an experimental basis, soon proved successful, and the coal company purchased the equipment for continued use. Two panels, adjacent to the first, were developed and mined with the planer. Each of these panels was shorter than the preceding one because water seepage from a surface creek limited development. On completion of mining in the third panel, the planer equipment was moved by the cooperating company to a nearby mine operated in the same coal bed where a large area of coal suitable for planer mining is available.

Jan 1, 1954

By L. E. Schultze

[The Bureau of Mines conducted bench-scale studies to develop techniques for stripping tetravalent cerium from tri-n-butyl phosphate solutions. Experiments were conducted in a constant-temperature bath using beakers and mechanical stirring. Ninety-five pct of the cerium was stripped from a 50-pct tri-n-butyl phosphate 50-pct kerosene solution containing 0.18 M cerium in 15 minutes at 50° C using 0.11 M aqueous formaldehyde.]

Jan 1, 1974

By J. G. Eisele

Solvent-extraction characteristics of dodecyl phosphoric acid (DDPA) were investigated to determine its potential as a fractional or selective extract-ant for individual elements in a rare-earth-yttrium mixture. The DDPA is an effective extractant for splitting rare-earth mixtures into light and heavy subgroups. Yttrium normally extracts with the heavy rare-earth elements but may be shifted toward an extraction sequence with the light rare-earth elements by increasing the pH. Elements in the light and heavy ends of the rare-earth series can be separated from middle-group rare-earth elements by using diethylenetriaminepentaacetic acid (DTPA) as an aqueous phase counter-extractant. Hydrogen-ion dependency of the distribution coefficients differs from that reported for similar systems at tracer-level concentration.

Jan 1, 1965

By S. J. Page, W. R. Reed, J. A. Organiscak

NIOSH continues to conduct respirable dust control research for surface mine blasthole drilling operations. Research areas have included testing variables (shroud leakage area, drill deck cross-sectional area, shroud height, collector-to-bailing airflow ratio, etc.) that have the most impact on respirable dust control, development of a dust collector inlet hood, development of a dust collector dump point shroud, and testing of a small diameter water separating sub. This paper summarizes the results of the aforementioned research that has been completed. Additionally, past dust control research for drilling operations of both underground and surface mines completed by the U.S. Bureau of Mines, created in 1910 and incorporated into NIOSH in 1997, is reviewed.

By V. R. Spironello

The Bureau of Mines is conducting studies of the slags related to ferrous technology to evaluate acceptable substitutes for the auxiliary flux, mineral fluorspar, in foundry operations. This work is directed toward the Bureau's goal of minimizing the Nation's dependence on scarce and critical minerals Comparative basic practice cupola (18-inch-ID) trials were made to evaluate a waste material called "used potlining," which contains significant levels of fluorine, sodium, and aluminum in various compounds. Used potlining is recovered from alumina reduction cells after its useful life, and was supplied by the Aluminum Co. of America (Alcoa) to the Bureau for evaluation. The material in the lump and pelletized form (with limestone) provided extremely fluid slags based on visual observation during cupola operation. No adverse effects were found on cupola performance, metal and slag chemistry, the environment, or mechanical properties of the castings produced. Fluorine recovery in the slag was equal to, or higher than, that of fluorspar; fluorine losses to the scrubber water and solids were lower. The acidity of the scrubber Hater was somewhat neutralized. No difference was observed in furnace-refractory attack, as determined by the level of magnesia in the slag and visual inspection. The recovery of sodium in the slag, presumably as the oxide, significantly increased slag fluidity, suggesting that less than equivalent fluorine may be required. There was no contamination of the gray iron by the aluminum from the used potlining. Used potlining was completely satisfactory as a substitute for fluorspar in cupola ironmelting.

Jan 1, 1981

Use controlled blasting techniques to reduce blast-produced overbreak damage to underground mine ribs and back for both safer working conditions and improvements in productivity. The Problem Blasting is used in metal and non-metal underground mine slopes, drifts and crosscuts to fracture rock to be excavated and further processed. Standard blasting also produces fractures in the rock beyond the desired excavation area. This is sometimes evident by rough surfaces, undercutting and other signs of excessive damage. This damage contributes to rockfalls in the mines, a major cause of injuries and fatalities, and equipment damage. A variety of controlled blasting techniques has been developed for civil engineering projects where long-term stability is essential. For several reasons, these methods arc not widely used in mining. For example, these methods incur additional costs and time; there is little need to maintain stable openings over long periods of lime; and there is the perception (hat corrective remedial techniques, such as rock bolting, are more practical. Basically the benefits of these methods are not demonstrably clear for application in underground mines.

Jan 1, 1991

By R. R. Nothdurft

The internal friction of eight single crystals of magnesium with orienta-tion ranging from 10° to 84° was measured at 33.5 kc and 272° C, and the results were interpreted in terms of the pinned-dislocation model proposed by Granato and Lucke. Results show that the strain-amplitude-dependent decrement varies with orientation in a manner predictable by the G-L model. Different values of strain-amplitude-independent decrement were observed at different orientation angles, but correlation with the theory was not conclusive. Problems and steps for further study are discussed.

Jan 1, 1965

By Frank G. Horino

This report describes an instrument designed by the Bureau of Mines for quantitatively identifying texture of rock surfaces produced by grinding or extremely rough surfaces beyond the range of commercial surface measuring instruments. The transducer for the instrument is a linear variable differential transformer that converts mechanical motion caused by surface roughness, waviness, and lay to an electrical output. The electrical output is recorded graphically as an X-Y plot of the line traversed on the rock surface. Details of the synthesized device and its calibration are given. The sensitivity of the unit is 2 percent of the scale setting of the amplifier. The horizontal scale is adaptable from ¼ inch to 15 inches of specimen length with a sensitivity of 0.01 inch if a 10 to 1 magnification is used and 0.1 inch if a 1 to 1 magnification is used.

Jan 1, 1968

By T. F. Dumm, O. Trass, V. R. Koka, L. G. Austin

"The size distributions of carefully screened 2 size fractions of ground materials were determined using a Microtrac laser dif-fractometer. The size distributions were fitted to the empirical function P(x) = 1/[1 + (x50/x)1] where P(x) is cumulative mass fraction less than Microtrac size, x. The standard deviation of A for a 50 second test time was approximately 0.5, so that seventeen test times give a mean with an estimated error within t 0.25 (95% confidence level). Values of were 5.44, 4.82, 4.40 for a coal ground under different conditions, indicating statistically different shape distributions; the average value for mica was 2.91 owing to the high aspect ratio of the particles. The ratio of x50 to the geometric mean sieve size was 1.2 for the coal and 0.70 for mica.1 IntroductionKoka and Trass have presented evidence [1,2] that materials ground in the Szego mill [3] give different shapes depending on the milling conditions. The variations in shape were deduced qualitatively by viewing SEM photomicrographs of selected 1/2 screen fractions. This paper quantifies their observed differences in shape by using measurements of the size distributions of screen fractions examined in a laser diffractometer [4] (Microtrac, Model 7991). The basic concept is that particles of 'a given ""screen"" size will give a wider distribution of ""Microtrac"" size when the particles are flaky with high aspect ratios, and a narrower distribution when the particles approach the cubical and spherical geometries.2 TheoryAustin and Shah [5] have shown that coal screened within a 1. 1/2 upper-to-lower sieve size range will give rise to a much wider distribution of Microtrac size. They found that the screen interval of irregular fragments of comminuted coals or quartz gave Microtrac size distributions which could be described by the simple function"

Jan 1, 1988

By Philip C. Good

The Bureau of Mines investigated the feasibility of utilizing low-grade phosphatic shale as a feed for phosphoric acid production. Present practice in the phosphate mining operations of southeastern Idaho is to remove and either stockpile or waste low-grade phosphatic shales as the high-grade phosphate beds are selectively mined. Acid digestion studies were performed on uncalcined shale and on shale calcined to remove free carbon to determine phosphoric acid quality, yield, and amenability to filtration. The untreated shale, containing 21.4 pct P205, was digested with sulfuric acid in a single-tank reactor to yield phosporic acid and gypsum residue. Although 96 pct P205 recovery was attained in digesting uncalcined shale, only the calcined product gave satisfactory filtration rates. Calcined shale yielded phosphoric acid recovery of about 93 pct of the contained P205. It was higher in impurities than commercially prepared acid derived from high-grade western phosphate rock. An acid filtration rate of 745 lb P205/ft2/day was attained. This value is lower than the rate of 900 lb P205/ft that is generally considered to be acceptable in industrial production of phosphoric acid from high-grade phosphate rock.

Jan 1, 1981

By John I. Kasteler

The Rambler mine is in the Douglas mining district, Albany County, Wyo. (fig. 1). The property was first operated about 1870 for gold found in the outcrop of a leached ore body. Copper and metals of the platinum group were discovered, in 1900, or soon thereafter, and intermittent mining was done until 1918, when a fire destroyed the surface plant, and the underground workings caved. The mine has since been idle. The Bureau of Mines conducted a development project on the property from October 1942 to October 1943, with a recess period between November 1942 and August 1943. Ten diamond drill holes, totaling 1,859 linear feet, were drilled on the property (fig. 2). The mine dump was sampled after preparation with a bulldozer. Assay determination and spectrographic analyses disclosed small quantities of copper and metals of the platinum group in the samples. Determinations were made on 11 samples from the diamond drill holes and 23 samples from the mine dump. The assay results and spectrographic analyses are given in tables 1 and 2. The logs of the diamond drill holes are given in an appendix to this report.

Jan 1, 1949

By Laxman S. Sundae

In the vast majority of American coal mines, roof bolt holes are drilled dry, mainly because of mine operator concern with the spent water creating adverse working conditions. Wet drilling, however, can increase drilling rates and the effective lifetime of the drill bits used. This study, carried out as part of an ongoing cooperative research program between the U.S. Bureau of Mines and the University of Missouri-Rolla, shows that the large volumes of water conventionally used in wet drilling are not necessary, and the performance benefits from wet drilling can be achieved with total volume flows on the order of 0.4 L per hole. This conclusion is validated based on the measured respirable dust generated in drilling Berea sandstone. The results are confirmed using a variety of bit shapes, which are also shown to have a significant effect on penetration rate.

Jan 1, 2010

By D. E. Hirsch

The Bureau of Mines has developed a systematic procedure for separation, characterization, and semiquantitative analysis of high-boiling (350° to 550° C) distillates of crude oils. Isothermal and molecular distillation were used to prepare the 370° to 530° C distillate of Recluse, Wyo., crude oil. The distillate was separated into fractions by chemical treatment, silica-alumina gel adsorption, and gel permeation chromatography (GPC). The fractions were analyzed by use of GPC correlations and mass and nuclear magnetic resonance (NMR) spectrometry. The increased knowledge of petroleum composition obtained from the data will contribute to improved petroleum processing and utilization and energy conservation.

Jan 1, 1974

By Jr. Reed

The only known large deposits of talc in Alabama occur near Winterboro, Talladega County. Preliminary examinations were made, and work by the Bureau of Mines was recommended. The deposits were investigated to determine the amount and grade of talc present and to search for new talc deposits in the general area. Seventy-five holes, totaling 3370.4 feet, were drilled with Government-owned core drills from August 1, 1948, to February 11, 1949, and 27 samples were taken for assay. This report presents the factual data disclosed by drilling and the results of beneficiation of the talc.

Jan 1, 1950

By F. R. McDonald

The compound ?-valerolactone has been identified in an acid fraction isolated from waste water collected from an in situ oil-shale retort. Infrared, nuclear magnetic resonance, and mass spectrometry were used by the Bureau of Mines to confirm the identification of a subfraction collected from a gas chromatograph.

Jan 1, 1974

By Harold L. Rhodes

The Bureau of Mines has developed a quantitative method to determine water vapor in helium in the range of 0.1 to 15 ppm by volume. This method uses the quantitative chemical reaction of H20 with CaH2, which produces 1 mole of hydrogen for each mole of H20 in the sample. A gas chromatograph is then used to determine the concentration of hydrogen in the product. The precision of the H20 analysis is ±0.05 ppm at a concentration of 1 ppm. This method is used to calibrate a commercial platinum-phosphorus pentoxide (Pt-P205) electrolytic water vapor analyzer that has an improved inlet system and digital voltmeter readout.

Jan 1, 1981

By M. R. Yenchek

The U.S. Bureau of Mines has determined a method for calculating coal mine portable power cable thermal life for a specified temperature loading. This work was the culmination of a multifaceted research project involving (1) accelerated life tests of insulation and jacket materials and (2) steady-state and cyclical loading of cables. Composite Arrhenius curves were derived for common insulation and jacket materials to identify the key cable quality that precipitates thermal failure. Plots of temperature rise versus current for popular cable sizes were then referenced to develop a correspondence between cable life, based upon thermal degradation and current loading. Predictions of cable thermal life were made through integration over variable load cycles and, consequently variable operating temperatures. This procedure may have utility for both the U.S. Mine Safety and Health Administration and mining machine designers in determining the appropriate cable size for new equipment.

Jan 1, 1991

By James A. Powell

A seismic system which utilizes in-mine geophones to detect trapped miners has been developed. Tests at the Bureau of Mines Safety Research Mine at Bruceton, Pa., and at two operating mines indicate such a system has a maximum detection range in excess of 1,000 feet. The system is fieldworthy and portable and requires less than 30 minutes to set up and check. Real-time detection is possible.

Jan 1, 1976

By B. J. Scheiner

As part of the goal to maximize minerals and metals recovery from primary domestic resources, design factors associated with minimizing current leakage in bipolar cell configurations were studied by the Bureau of Mines as a means of improving the efficiency of bipolar e1ectrooxidation cells. Initial studies that were conducted in a small bipolar cell operating at 140 to 145 volts and 15.4 amp indicated how design factors could be employed to minimize cur-rent leakage around adjacent electrodes during cell operation. Based on these results, a 40-electrode, 108-kva prototype of an industrial-sized cell was constructed and tested for extracting metal values from offgrade molybdenite concentrates. The feasibility of recovering molybdenum and rhenium from the oxidized pulp also was determined. Feed to the process sequence consisted of flotation concentrates containing 16 to 35 pet Mo as molybdenite and 6 to 15 pct Cu. E1ectrooxidation in the prototype cell resulted in 84 to 97 pct Mo and Re extraction with a corresponding energy consumption of 9 to 13 kwhr/1b Mo extracted.

Jan 1, 1979