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By Renpei Yoda

An investigation was conducted to develop columbium alloys with e1evated-temperature strengths higher than those exhibited by more common commercial columbium alloys, and attention was given to improving the oxidation resistance and ease of fabrication. Additions of carbon, aluminum, and chromium were made to some columbium-base alloys, and their effects on workability, recrystallization, oxidation resistance, and mechanical properties at elevated temperatures were explored. The additions were made to take advantage of (1) solid solution strengthening, and (2) precipitation hardening. Three alloys displayed good high-temperature properties with relatively good oxidation resistance at 1,000° C, and tensile strengths from 26,000 to 32,200 psi at 1,400° C. When the properties of these alloys were compared with those of commercial alloys, B-66 and FS-85 (1),4 the outcome was favor-able for the alloys studied in this investigation.

Jan 1, 1967

By E. Miller, J. M. Eldridge, K. L. Komarek

The thermodynamic properties of liquid Mg-Ge alloys have been determined between 1000°and 1500°K by an isopiestic method. Germanium specimens, heated in a temperature gradient and contained in covered graphite crucibles of special geometry, were equilibrated with magrtesium vapor in closed titanium tubes. The crucible design allowed free access of magnesium vapor to the samples during the equilibration to form alloys of magnesium and germanium, but prevented magnesium losses from the crucibles on quenching the titaniuin tubes to terminate the experimental runs, thus preserving the equilibrium alloy compositions. The activities and partial molar enthalpies of magnesium and the integral thermodynamic properties of the system were calculated from the experimental data. THE Mg-Ge phase diagram' shows one congruent melting compound, Mg2Ge, of essentially stoichio-metric composition, two eutectics, and very limited terminal solid solubilities. Very little information is available on the thermodynamic properties of the Mg-Ge system. The free energy of formation of Mg,Ge was recently deter-mined2 by a Knudsen cell technique in the temperature range 610° to 760°C. The standard enthalpy of formation of Mg,Ge was measured calorimetrically by Bever and coworkers.3 The present study was undertaken as part of a general investigation of the thermodynamic properties of the homologous series of Mg-Group IVB systems, i.e., Mg-Pb,4 Mg-Sn,5 Mg-Ge, and Mg-Si. An isopiestic technique was used which was developed by the authors5 for investigating the thermodynamic properties of liquid Mg-Sn alloys. Specimens of the nonvolatile component, contained in covered graphite crucibles, are heated in a temperature gradient in an evacuated and sealed titanium reaction tube, and equilibrated with magnesium vapor of known pressure. The method employs crucibles of special geometry which preserve the high-temperature equilibrium composition of liquid alloys having a highly volatile component such as magnesium on termination of the experimental runs by quenching the crucibles to room temperature. EXPERIMENTAL PROCEDURE First reduction germanium of 99.999+ pct purity (Eagle-Pitcher Co., Cincinnati, Ohio) and 99.99+ pct magnesium metal (Dominion Magnesium Ltd., Toronto, Canada) were used. The graphite crucibles were machined from high-density (1.92 g per cu cm) graphite rods (Basic Carbon Corp., Sanborn, N.Y.) which had a maximum ash content of less than 0.04 pct. The non-reactivity of graphite with germanium at the temperatures used in this study had been previously established by Scace and Sleck.6 The experimental procedure has been previously described in detail.5 The selection of a particular crucible geometry for a run was determined by a combination of imposed experimental conditions, the principle being that more tightly covered crucibles were required to preserve alloy compositions during quenching when higher magnesium pressures and higher specimen temperatures were used. Depending upon the composition range of the equilibrated alloys the source of the magnesium vapor was either pure magnesium or a two-phase mixture of Mg2Ge + Ge-rich liquid of known magnesium pressure. The experimental runs can be divided into the following three groups on the basis of crucible geometry and magnesium source material. Crucibles with Small Holes and Pure Magnesium Reservoirs. The crucible dimensions were identical to those of the Mg-Sn investigation5 except that the hole diameters were reduced to 0.010 in. because of the higher temperatures and higher magnesium pressures involved in the Mg-Ge system. During an equilibration run, magnesium vapor diffused from the reservoir to each specimen through the small holes, one drilled through the crucible lid and two others drilled through graphite baffles positioned vertically inside the crucible between the lid hole and the specimen. Since the magnesium pressure was high, i.e., in the range 117 to 277 Torr, during the equilibration time of approximately 24 hr, equilibration was not impeded by these holes. A specimen composition at equilibrium was fixed by the relative temperatures of the specimen and the reservoir, and by the thermodynamic properties of the system. Upon brine quenching the titanium reaction tube to end a run the vapor pressure of magnesium above the liquid alloys decreased exponentially with decreasing temperature, and the small cross-sectional areas of the holes (4.9 x 10"* sq cm) drastically reduced magnesium losses from the crucibles. Because of its low vapor pressure, germanium losses from crucibles during a run were at most 0.2 mg for pure germanium and correspondingly less for the alloys. This crucible geometry satisfactorily retained the equilibrium alloy compositions on quenching for magnesium-rich (from 3 to 33 at. pct Ge) alloys provided their temperatures were below the melting

Jan 1, 1967

By F. L. Kadey

A discussion of fillers would not be complete without allotting adequate time to that unique and different mineral material, diatomaceous silica. Historical references to its use challenge the aesthetic aspect of man's curiosity; whereas modern scientific tools have provided a dimension of measurement that has motivated many of its more recent applications. A brief review of what is already known is in order. The diatom is a unicellular, plant-like, microscopic organism, related to the algae1. Its natural function appears to be that of a food for other marine or lacustrine organisms, The diatom's "claim to fame" from an industrial viewpoint is dependent on the fact that it secretes an opaline siliceous skeleton that must survive, chemically and structurally, the geologic processes that caused its formation in the first place; its subsequent demise, burial, consolidation, and alteration; and finally, its ultimate exploitation by man--in somewhat that order. In addition to its siliceous nature, the skeletal structure of the diatom possesses a variety of shapes, patterns, and sizes that have not only been the intrigue of microscopists for decades, but have served to set diatomite apart as an industrial mineral; and have reserved for it applications that cannot be satisfied by any other material. Its chemical inertness, its intricate structure, and its intrinsic hardness-coupled with fineness and friability-- are generally known and have accounted for its application in a wide range of filtration and filler uses. The increasing use of the electron microscope has considerably expanded our knowledge of heretofore unseen secondary and tertiary structure of submicron dimension in the diatom valve. The development of electro-sensing methods of particle size measurement which seem to supersede sedimentation and microscopic techniques has portrayed size distribution in a more realistic light. Interest in the surface chemistry of these silica structures has further strengthened our understanding for certain uses. Thus, new tools and ideas have made possible the introduction of diatomite into such sophisticated technologies as that of chromatographic supports, its improved utility in paint applications for the control of gloss and sheen, and its usefulness in the entirely new concept of "Dry Acid Concentrates." Each of these applications has been discussed elsewhere before people particularly interested in analytical chemistry, in paint, and in liquid handling, respectively, where the diatom has been a means to an end. The emphasis here, before the mining fraternity, however is on diatomite as a raw material with reference to the uses mentioned above. It is therefore toward an awareness and understanding of diatomite properties pertinent to these newer filler applications that this paper is directed.

Jan 1, 1967

By Thomas R. Bur

The strain and pressure gage methods for evaluating the relative performance of explosives in rock were compared. This comparison was based on a study of the responses of strain and pressure gages to explosion-generated seismic waves. Several explosives) representing a wide range of detonation pressures) were used. In general the relative performance of these explosives) as determined from amplitude) impulse parameter) and energy parameter measurements) is the same if the compressive portion of the strain pulse and the comparable portion of the pressure pulse are considered. Other similarities and differences of the two methods are also discussed.

Jan 1, 1967

By F. R. McDonald

This report presents a discussion of the spectra of 39 condensed thiophenes in which the structure includes at least 1 benzene ring. The vibrational bands present in three regions of the infrared spectra of these thiophenes were interpreted by comparing the similarities of the spectra of condensed thiophenes with the spectra of substituted benzenes. In the overtone-combination region 23 of the 39 condensed thiophenes had spectra which contained sufficient detail to be usable for correlating this region of the spectrum with the appropriate benzene spectrum. In the in-plane deformation region it was possible to make correlations for the vibrations of 18 of the 39 condensed thiophenes whose infrared spectra were studied. In the out-of-plane deformation region the C-H out-of-plane vibrations for hydrogen on benzene rings in the condensed thiophenes can be correlated using known data from substituted benzenes.

Jan 1, 1967

By E. J. Murphy

The Bureau of Mines developed a fast, reliable modification of the Griess-Ilosvay procedure suitable for field analysis for NO2 in the fumes from explosives. Known concentrations of NO2-air mixtures were analyzed for the nitrous acid or nitrite formed in the reaction with three Griess-Ilosvay-type reagents by diazotizing and coupling. Comparison was made of the Rider-Mellon, Saltzman, and Patty-Petty procedures; the three procedures are in agreement if sufficient time of contact between NO2 and the reagents is allowed. In experiments to obtain an accurate factor for converting NO2 to nitrite, overnight contact was allowed in order to be sure conversion was complete. The factor was found to be 75 percent with a standard deviation of ±3.2. Low and erratic results were found using either the Saltzman or Patty-Petty reagents as absorbing liquids unless several hours' contact was allowed. If dilute NaOH solution was used as the absorbing liquid instead of a Griess-Ilosvay-type reagent, 92 percent of the overnight conversion factor was found after a 3-minute shaking time and a la-minute standby time. The Saltzman reagent was preferable for fieldwork with the dilute NaOH solution as the absorbent because of its easy application, rapid reaction, and intense color even at low NOB concentrations.

Jan 1, 1967

By J. W. Spretnak

It is well-established that decohesions occurring at the interface of the matrix and rigid inclusions and second-phase particles are prime causes of ductile fracture initiation. It is not clear, however, how these decohesions occur. The idea that the interface bond is broken in tension is not particularly attractive when one considers the strength of such interfaces and the fact that plastic flow is not restricted under conditions of continuing flow required to initiate and propagate ductile fracture. A suggestion as to the mechanism of decohesion arises if one takes the position that, as the dislocation density increases with plastic flow and reaches some critical range of density, the phenomenon of flow can be regarded as fluidlike instead of the crystallographic motion of dislocations. As the spacing between dislocations decreases, the matrix becomes increasingly disordered in terms of loss of periodicity. At some critical degree of reduction of the periodicity, it is suggested that flow can be regarded as hydrodynamic, rather than crystallographic. Such a state has been referred to by rheologists as the "plasticized state", or the "fourth state of matter", between the liquid and solid state. A similar argument pertains qualitatively with the increase in equilibrium vacancy concentration as the temperature approaches the melting point. Taking the viewpoint that at larger strains the flow may become hydrodynamic in nature, a mechanism of decohesion is suggested. A well-known phenomenon in boundary-layer flow is that of "separation" locally of the boundary layer from the substrate.' Under certain conditions, the flow in the immediate neighborhood of the substrate becomes reversed, causing the boundary layer to separate from it. The exact condition for separation is that the velocity gradient normal to the substrate vanishes there, or It is of interest that blunt particles such as spheres and circular cylinders are most likely to give rise to separations because of unfavorable pressure distributions behind them. The source cited gives solutions for positions of separations for various geometries. In principle, such separations can also take place when metal is flowing over a "dead zone" of stagnant metal. This may explain the initiation of fracture at the elastic-plastic boundaries of plastic enclaves under a notch.

Jan 1, 1967

By Harry C. Gatos, Frank J. Bachner

It was shown through high-pressure experiments that tin loss by volatilizatim is necessary for the degrada-tion of the superconducting transition temperature of Nb,Sn associated with high-temperature annealing. Crystallochemical analysis of the degraded Nb3Sn showed that it constitutes a new phase with ordered niobium-site vacancies, created by the migration of niobium atoms to vaccnt tin sites. This new phase was found to form when 4 pct Nb-site vacancies were present. It has a transition temperature of 6'K and a lattice parameter of 5.283A. A similar degradation effect was observed in Nb,Al. Its superconducting transition temperature dropped from 16.5" to 8" K following a high-temperature annealing. The superconducting temperature degradation in these 0-tungsten structure compounds is attributed to the disruption of the interchain d bonding by the periodic interruption of the niobium atom chains. By annealing the degraded Nb, Sn at 1000 C in nitrogen its normal superconducting behavior is restored most likely due to the incorporation of nitrogen atoms causing the elimination of the ordered vacancies. HANAK et al.' have observed low superconducting transition-temperature values (T, - 9"K) in some NbsSn samples deposited from the vapor phase. They attributed such low T, values to disorder in the 0-tung-sten structure. Much lower T values (down to 5.6"K) were reported by Reed et al.zC for NbsSn samples annealed at high temperatures. These authors also attributed this degradation effect to disorder (random occupation of the A and B sites by niobium and tin) but pointed out that such disorder could be brought about (by high-temperature treatment) only in samples containing niobium in excess of the stoichiometric composition NbsSn. Both groups reported that the normal superconductivity behavior could be rever-sibly restored by appropriate heat treatment. Courtney et al., also found that degradation in NbsSn requires excess niobium brought about by the loss of tin during the treatment. However, these investigators proposed that the degradation is due to niobium-site vacancies resulting from the migration of the niobium atoms to the vacated tin atom sites. They did not consider the reversibility of the effect. The present study attempts to establish the nature of the above degradation phenomenon. EXPERIMENTAL PROCEDURES All compounds prepared for this investigation were made from the powders or filings of the elements which were intimately mixed, cold-pressed into a cylindrical pellet at approximately 50,000 lb per sq in., and then submitted to the desired heat treatment. The samples annealed under high pressure were placed in a MgO sample container which was mounted in a pyrophyllite tetrahedron designed for a tetra-hedral-anvil press. Details of the experimental arrangement are given elsewhere. This setup allowed heating at 1800°C or above under pressures in excess of 30kbars for 3 hr. The samples annealed in a vacuum were prepared in a high-temperature vacuum furnace which could reach temperatures up to 2400°C under a pressure of 2 x lo-' Torr. For annealing in a reactive atmosphere, a quartz tube was placed in a clamshell furnace and the desired gas ambient passed through the tube. Lattice parameters were determined using a Debye-Scherer 114.6-mm camera. Cohen's method, programmed for the IBM 7094 computer, was used to calculate the lattice parameter from the measured d spacings. X-ray integrated intensity measurements were made on several samples. These samples were ground to -400 mesh and the powder mixed with a solution of collodion in amyl acetate. The mixture was poured into a depression milled in a bakelite disc. When the mixture dried, the surface of the disc was ground flat leaving a diffraction surface defined by the face of the disc. The disc was mounted in a Philips rotating specimen holder which allowed the rotation of the sample in the plane of the diffraction surface and the integrated intensity measured using a scintillation counter and a pulse-height analysis sys-tem. The superconducting transition temperatures were determined by means of self-inductance techniques.' EXPERIMENTAL RESULTS AND DISCUSSION The Role of Tin Loss in the Degradation of Super-conductivity. The loss of tin during high-temperature annealing can be effectively suppressed by annealing under high hydrostatic pressures. Accordingly, a series of experiments were performed under pressures of approximately 30kbars. This pressure was the minimum under which high-temperature experiments could be safely performed in the particular pressure apparatus employed. Experiments were also designed to test high-pressure effects on the superconductivity behavior of NbJSn. The results of the high-pressure annealing experi-ments are summarized in Table I. All samples were prepared as described earlier. They were reacted and homogenized at 1000°C for 24 hr under argon at-

Jan 1, 1967

As part of its regular program to provide timely information on domestic mineral commodities, the Bureau of Mines conducted an engineering appraisal of more than 1,300 lode and placer gold deposits in the United States to deter-mine their gold production potential. While these deposits were estimated to contain over 400 million ounces of gold, only 9 million ounces, or slightly more than 2 percent, was found to be producible at $35 per ounce under prevailing mining and metallurgical technologies. The study revealed that any significant increase in available gold in the United States is most likely to come from the discovery of new sources, intensive exploration and development of the more promising known mineralized areas, and development of new or improved mining and metallurgical techniques.

Jan 1, 1967

By Karl-Heinz Frohne

This report presents the findings of a study of a portion of the Clover-Rush Run oilfield located in Roane County, W. Va. The study was made to investigate the possibilities of secondary oil recovery in the Big Injun sandstone underlying the William Kaufman lease. Reservoir properties, original reserves, and primary oil recovery are also presented. The investigation is based on a core analysis and related laboratory tests, well records, field production data, and subsurface information from the Kaufman property. A theoretical primary oil recovery of 9.7 percent of original oil in place is predicted for the reservoir. A waterflood performance prediction of a hypothetical pilot area was made by use of a computer. The prediction showed that, based on laboratory oil water relative permeability curves, the water-injection time needed to initiate oil production is excessive and that the stabilized water-injection and corresponding oil-production rates are very low. This precludes waterflooding the reservoir on an economic basis. A prediction for secondary oil recovery by gas injection was attempted but could not be completed because essential reservoir data were not available. In July 1965, the lease operator initiated, and is currently conducting, a gas-injection program, but there had been no increase in oil production up to November 1966.

Jan 1, 1967

By Walter Pajalich

This Bureau of Mines report is a study of the organizational framework of the ferrous scrap industry, of the products produced, and of the factors affecting the consumption of ferrous scrap by the steel industry. Consumption data from 27 major iron and steel firms in the States of Illinois, Indiana, Iowa, Michigan, Minnesota, and Wisconsin during the period between 1957 to 1962 were grouped by type of iron and steel furnace production facilities to determine consumption pattern for various grades of scrap in comparison to ingot production, hot metal consumption, and home scrap generation. Grades of scrap affected by changes in scrap consumption were determined, and the pattern that emerged was analyzed. Correlation of scrap demand and its effects on scrap prices based on price of scrap receipts of No. 1 heavy melting scrap and No. 2 bundles in the Chicago area for the years 1957 through 1962 indicated that demand trends do not always affect the price of scrap, Past and present technological advancements in steelmaking processes are discussed, and their effects on the scrap industry are analyzed.

Jan 1, 1967

By R. A. Friedel

THE IMPORTANCE of infrared and ultraviolet-visible spectrometry in studies of the structure of coal and similar substances is described. Special experimental techniques have been developed for these studies. Thin sections of coal are preferred, but halide pellets are easier to prepare. Information obtained from infrared spectra on chemical functional groups has been discussed; the importance of both intensities and wavelengths of absorption bands has been emphasized. Functional groups assigned include aliphatic and aromatic CH, methylene and methyl groups, hydrogen-bonded hydroxyls, hydrogen-bonded and chelated carbonyls, phenolic structures, minerals, and aromatic structures that are benzenoid or polynuclear. Infrared studies of structures of coal extracts, distillates, and reaction products of various processes, both chemical and physical, are discussed. Coallike infrared spectra of chars of model compounds have been utilized extensively in studies of coal structure. Ultraviolet-visible absorption spectra of coals show a lack of fine structure and low spectral intensities. These results have been applied to the questions of the chemical and physical structure of coal, particularly the question of polynuclear aromaticity of coals. The color of coal is also treated. The physical-chemical origin of the color of coal may be due to free radicals, as interesting correlations of ultraviolet-visible spectra with electron paramagnetic resonance have been obtained. The optical color of coal has been explained and simulation of the color changes observed in thin sections has been carried out, The spectra and structure of coal derivatives and other carbonaceous materials are also discussed. Possible sources of error in absorption spectral measurements are pointed out. Limited measurements of the ultraviolet-visible reflectance spectra of coal are described.

Jan 1, 1967

By Katherine Harding

Basic concepts of matrix algebra and manipulations of matrices are presented in such a way that little competence in mathematics is required. Examples are always included to illustrate concepts and techniques. The paper is divided into six sections. The first four sections are devoted to some of the more basic concepts of matrix algebra, whereas the last two sections are concerned with specific applications.

Jan 1, 1967

By Donald Ofte

LIQUIDUS temperatures of molten alloys were measured in an oscillating-cup viscosimeter by observing the abrupt increase in the alloy viscosity when the apparatus was cooled below the alloy liquidus temperature. The liquidus transformation can be an elusive thermal effect in an alloy system where a small amount of material is involved in a low-enthalpy liquidus reaction, or where other unfavorable physical conditions interfere. Using the viscosity technique, liquidus temperatures were measured in binary alloys of plutonium with cerium, gallium, and iron, as well as ternary Pu-Ce-Co alloys. The previously described oscillating-cup viscosimeter1 is a torsion pendulum consisting of a right circular, cylindrical tantalum cup fitted to a rigid shaft which, in turn, is suspended by a torsion fiber in a highvacuum system. When the torsion pendulum is placed in oscillation the viscosity of the liquid contained in the cup is a function of both the decay of the oscillation caused by the viscous drag of the liquid contained in the sealed tantalum cup, and the period of the oscillation. The period is measured by a photo-electrically operated timer to the nearest thousandth of a second. Prior to each measurement, the apparatus is held at temperature between 5 and 18 hr to assure thermal equilibrium throughout the 8 to 10-cc alloy sample. When the cup, filled with a liquid metal, is oscillating. only a very thin outer layer of the fluid is in motion. This moving annulus represents the liquid's contribution to the moment of inertia of the torsion pendulum. When the viscosity increases, more liquid is placed in motion, and the slight increase in the moment of inertia causes a corresponding increase in the period of oscillation.

Jan 1, 1967

By P. Wynblatt, J. E. Dorn

The effect of strain rate, temperature, and interstitial impurity concentration on the flow stress was investigated in a poly crystalline Fe-2 pct Mn alloy. The temperature dependence of the flow stress was found to be independent of the interstitial impurity concentration, removal of interstitials merely decreasing the atherma1 stress level. Below 160%, the large temperature dependence of the flow stress was interpreted in terms of the Dorn-Rajnak theory of the Peierls mechanism of plastic deformation. Above 160"K, some other thermally activated intrinsic meckanisln seems to be operating. The strong temperature dependence of the flow stress of bcc iron at low temperatures has been studied by numerous investigators and interpreted in terms of several different thermally activated dislocation mechanisms. The following mechanisms have been proposed: a) interaction of dislocations with interstitial impurity atoms1 or with solute atoms in general; b) interaction of dislocations with clusters of impurity atoms;3 c) resistance to the motion of dislocations due to jogs on screw dislocations;* d) resistance to the motion of dislocations due to the Snoeck effect;' and e) interaction of dislocations with the intrinsic resistance of the bcc lattice or Peierls "hills". In previous work: it was found that the plastic behavior of polycrystalline iron containing 2 wt pct Mn (and 100 ppm C + N) is in good agreement with predictions based on the Peierls mechanismlo from 77" to 160°K whereas from 160" to about 370°K another as yet unidentified thermally activated mechanism is operative. The purpose of the present investigation was to determine the effect of interstitial impurities on the temperature dependence of the flow stress, by purifying the previously investigated alloy with respect to interstitial impurities. The investigation revealed that removal of the interstitial impurities to a level that eliminated Cottrell locking and the Portevin-LeChatelier effect (i.e., serrations in the stress-strain curve due to dynamic strain aging) affects neither the strong temperature dependence of the flow stress at low temperatures nor the general characteristics of the higher-temperature behavior. Such purification, however, lowered the athermal yield stress. I) EXPERIMENTAL PROCEDURE AND RESULTS The material used in this investigation consisted of an Fe-2 wt pct Mn alloy having the following additional elements present: 0.004 pct C, 0.006 pct N, 0.05 pct 0, 0.004 pct S, 0.003 pct P, and 0.001 pct Si. This was the same material as that studied in the previous investigation and will henceforth be referred to as the "impure material". The as received -jr by 2 in. hot-rolled bars were cold-rolled to 0.08-in. thickness, recrys-tallized under argon for 30 min at 80O0C, and further cold-rolled to 0.053-in. thickness. Flat tensile specimens 3 in. wide having a 1.625-in.-long gage section were machined from the sheet and then purified. The first stage of purification consisted of holding the specimens at 850°C for 24 hr in a stream of hydrogen saturated with water vapor at room temperature. Material prepared in this fashion will subsequently be referred to as "wet hydrogen purified material". It has been estimated that this type of treatment reduces the carbon content of iron to less than 5 ppm.' The second stage of purification consisted of holding the specimens in a closed system through which hydrogen was circulated past the heated specimens as well as a zirconium hydride getter. The specimens were held at 850°C and the getter at 800°C. The process was continued for 212 hr. The starting material for this process was wet hydrogen purified material. Material prepared in this manner will be referred to as "ZrHz purified material". The technique used was substantially the same as that described by Stein et al.' who have shown that the carbon level at the end of the process is reduced to about 5 parts per billion. The mean grain size of the three materials was found to be -60 C( for the impure material and -160p for the wet hydrogen and ZrHz purified materials. All tensile testing was carried out on an Instron Testing Machine either in controlled-temperature baths or at fixed-point baths such as boiling liquid nitrogen, and so forth. When fixed points were used the temperature was kept constant to better than *1°C whereas in all other tests the temperature variation was less than *2°C. Test of Purity. It was not possible to determine the purity achieved at each stage of the purification because the resulting level of interstitial impurities was near or below the limit of sensitivity of standard analytical techniques. It was possible, however, to obtain a qualitative measure of the extent of purification from the appearance of the stress-strain curves for the three materials. Fig. 1 shows the stress-strain curves for the three different materials tested at 300°K. It can be seen that the effect of wet hydrogen

Jan 1, 1967

By David E. Nicholson

In a Bureau of Mines investigation of the dynamic compaction of mine hydraulic backfills, two basic forms of mechanical vibration inducers were used and compared for effectiveness of compaction. Internal compaction, using concrete probe vibrators of various sizes, and external compaction, using plate vibrators} were studied and evaluated for use in underground stopes. An aluminum plate, which was light and displaced sufficient volume to remain afloat in fluid fill, and a steel plate were both used in the external compaction tests. Efficiency of compaction was better in studies conducted with internal probe vibrators. Tests were conducted in an underground backfilled stope with three different-sized probe vibrators (2-, 4-, and 6-inch-diameter) to determine an approximate area of influence. Results showed the areas of influence to be approximately 3, 4, and 5 feet in diameter, respectively, for the three different probes. Physical properties of hydraulic slurries were determined; preferred grain-size distributions, water exudation properties, and water contents of hydraulic slurries are reported. The best compaction results were obtained with moderately well-graded, fully saturated backfills, with slow rates of water exudation, which were capable of remaining in a semifluid state during the compaction process.

Jan 1, 1967

By P. M. Robinson, J. S. LI. Leach

The heats of solution oj' indiurrr, tin, lend, nrzd tellurium have been calculated from the measured heat effects when mechanical mixtres of indium and telLuium tin and tellurium, and lead and tellurium were added to liquid bismuth. The results are in good agreement xith publislzed values.s for the separate sollction of each eleltzent in bismuth. The heats oj solution of cadmium and tellurium calculated from the rneasuved heat effects on adding trechanical mixtures of these elements do not ugree zc,itl the published values jbv the separate solution of each element. It is shown that at 623°K Ile interaction between cadmium and tellurium dissolved in liquid bismuth is strong enough to led lo preciPitation of solid CdTc. The heats oj- jor-mation of CdTe at 273" nd 623°K (1)-c crilculated fi-or the measured heat ejlfecls. The calcnlaled az'erage deviation from the Kopp-l\'ez?,zunrz rule fov solid CdTe is less than 0.06 cat per g-atom- C over this lertzperalure range. Tlze importance 0.f these oDserl.ations to the determination of heals of formation hy metal solution calorimetry is considered. LIQUID metal solution calorimetry is a convenient method for determining the heats of formation of solid compounds. In this technique the heat of formation is the difference between the measured heat effects on dissolution of the compounds and of mechanical mixtures of the components in the liquid metal.' The heat of solution of the mechanical mixture may be calculated from the measured heat effect. At infinite dilution of the solutes, this heat of solution is equal to the sum of the heats of solution of the separate components. If the heat of solution of one of the components is known, the value for the other can be derived; if both are known, they may be used to check the accuracy of the calorimetric technique. The heats of formation of the tellurides of cadmium, indium, tin, and lead have recently been measured by metal solution alorimetr. The heats of solution of indium, tin, lead, and tellurium at infinite dilution in liquid bismuth at 623"K, calculated from the measured heat effects on solution of the mechanical mixtures, are in good agreement with the published values. The heats of solution of cadmium and of tellurium calculated from the measured heat effect on solution in bismuth at 623'K of mechanical mixtures of cadmium and tellurium, however, do not agree with values estimated from the literature. 1) EXPERIMENTAL PROCEDURE AND RESULTS The Heats of Solution of Indium, Tin, Lead, and Tellurium in Bismuth. The heat effects were measured when mechanical mixtures corresponding to the compounds In,Te, InTe, In2Te3, In2Te5, SnTe, and PbTe were dissolved in bismuth. The calorimetric procedure and the method of calculation have been described elsewhere.' The heats of solution of the mechanical mixtures were obtained by subtracting the change in heat content per gram-atom of the sample between the addition temperature (273°K) and the bath temperature (623"K), (H623°K - H273°K)S, from the measured heat effects. The calorimeter was calibrated with pure bismuth. The reported values of the measured heat effects are based on (HGoK - ^273oK)Bi = 4.96 kcal per g-atom.3 The measured heat effects are found to be linear functions of the solute concentrations of the bath in the dilute solution range. The values, extrapolated to infinite dilution, are listed in Table I, together with the heats of solution of the mechanical mixtures calculated using the published values of (H 623°K - H273°k)s for indium, tin, lead,3 and tellrium. All the error limits quoted in this work represent the spread of values obtained. The heats of solution in liquid bismuth at 623°K of mechanical mixtures of indium and tellurium in four different proportions were determined. Values of the heats of solution of the two components were then calculated from the resulting four simultaneous equations: The heats of solution at infinite dilution of tin and lead in liquid bismuth at 623°K were calculated from the heats of solution of the mechanical mixtures of tin and tellurium and of lead and tellurium using the heat of solution of tellurium calculated above. These values of the heats of solution are listed in Table I1 together with some published values for comparison.

Jan 1, 1967

By F. A. Skirvin

Purification techniques were investigated for removing low-level metallic impurities from tungsten hexachloride. These techniques included distillation) fused-salt scrubbing) zone refining) and adsorption. Fractional distillation of tungsten hexachloride was found to be an effective purification method. The impurity levels of molybdenum) iron) nickel) copper) magnesium) and manganese were reduced to provide a tungsten halide sample which contained a total of less than 10 ppm detectable metallic impurities. Purification by fused-salt scrubbing of tungsten hexachloride in a lithium chloride-potassium chloride eutectic produced a hexachloride product which was of approximately the same quality as that obtained by distillation. Zone refining and adsorption did not appear to be as effective as distillation or fused-salt scrubbing.

Jan 1, 1967

By Harry Elkin

Control of coal dust has long been an important aspect in the conventional mining of coal; the main reasons being from a health and disaster standpoint. With the advent, of mechanized longwall mining, the control of dust has required more attention due to the high extraction rate common to most longwall systems. The purpose of this paper will be to describe the dust abatement activities of the longwall operation at Sunnyside. Kaiser-Steel Corporation has three mires located at Sunnyside, Utah, with a total production averaging 6,800 tons of clean coal per day. Of this 6,800 tons, 71 % is mined with continuous miners, the remaining 29% coming from one longwall unit located in No. 3 Mine. Our first longwall panel was started in November, 1961. In October, 1966, we started mining our seventh panel. The present panel is located in the Upper Sunnyside Seam which averages five feet in thickness, but does get as low as 51 inches. The seam pitches 5.5% in this vicinity. The roof is generally good and is comprised of 10 inches of shale cap rocs overlain with sandy shale and sandstone. The floor is sandy shale and is quite undulating in nature. The present panel is 3,800 feet in length with a face of 670 feet. The major equipment employed on our longwall unit is a 125 H.F. Anderton Shearer-Loader, British Jeffrey Diamond armored conveyors and a Dowty self-advancing-roof support system. The Anderton Shearer in use on our longwall unit has a 60" diameter x 27" cutting drum. During the shearing cycle, it traverses the face at 20 feet per minute with a cutting rate of 7.5 tons/minute.

Jan 1, 1967

By G. G. Campbell

The Bureau of Mines in cooperation with Quaker State Refining Corp. conducted two underground-combustion oil-recovery experiments in the Venango Second sandstone in the Reno pool, Foster-Rena-Oil City field, Sugar Creek Township) Venango County, Pa.) to determine the applicability of the process for reservoirs producing Pennsylvania-grade paraffin-base crude oil. Tests were terminated when analyses of produced gas showed that a self-sustaining combustion front did not exist. It was thought that insufficient fuel had been deposited in the formation. Laboratory retort tests made after the second field test was concluded showed that crude oil from the Reno area would deposit enough fuel to support combustion if air flux, temperature, and time were maintained within defined limits.

Jan 1, 1967