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By K. R. Garr, D. Kramer, A. G. Pard

EXPOSURE of steels to a fast-neutron flux results in helium generation by (n,a) reactions. The elements Fe, Ni, Cr, and N are major participants in the (n,a) reaction and helium concentrations of up to 5 x 10"5 atom fraction could accrue in fuel clads after a year of service in proposed fast reactors.' Such concentrations of helium can severely reduce the ductility of alloys at temperatures of reactor service. The phenomenon of helium embrittlement has been studied in austenitic alloys which were irradiated with particles as a rapid means of producing significant helium concentrations.2-5 The pres-ent work is a continuation of those studies and is concerned with helium effects in a ferritic stainless steel. I) EXPERIMENT Small sheet tensile samples with a gage length of 0.50 in. and a cross-section of 0.009 by 0.040 in. in the gage length were punched from cold-rolled type 405 stainless steel. The composition of the steel used in this work is given in Table I. Prior to helium injection, the samples were annealed 24 hr at 760°C which caused complete recrys-tallization with a resulting grain size of 40 u. This treatment rendered the alloy completely ferritic and carbide particles, 0.5 to 2 uin size, were present at a density of 1 x 1011 cm-3, Fig. 1. These carbide particles were probably a mixture of the M7C3 and M4C types.6 Helium was injected into the samples by irradiation with a particles from a cyclotron, which produced uniform concentrations through the center two-thirds of the sample thickness. Details of this procedure were previously described.' The average helium concentration, as measured on a gas-source mass spec- 11) RESULTS A) Tensile Tests. The results of the tensile tests are given in Table I1 where the values shown are averages of two samples. There was no significant effect of helium on either the yield strength or tensile strength at 550" or 650°C but an increase in both is apparent at 750°C. Samples with helium showed a 20 pct loss in total elongation at 650°C which increased to a 55 pct loss at 750°C. The uniform elongation is not affected by helium at 550" or 650°C but shows an increase at 750°C.

Jan 1, 1970

By B. C. Allen

Grain-boundary gvoocing was studied irz chronziu?n. molybdenum, tungsten, and the solid-solution alloys, Cr-35Re. Mo-33Re, and W-25Re at 0.6 to 0.9 of the absolute liquidus temperature under an inevt atmosphere , foveign nzetal zlapor, and liquid metal. The controlling mechanism of matter transport was deduced frolr groove size and shape. kinetics of growth, and cotnparisoz with theoretical relatiotzships derived by Mullins. Grooves in chowzizon formed prittzarily by volume diffusion tkrongk kelium or argon at 1 atm pressure and by e1)apovation-condensatiotz in a static vacuum. Groozles in the other nzetals and alloys forrned priniarily by sirface diffusion, the coefficients of which were calculated. Carbon was found to decrease the acti7:ation energy for surface diffusion on molybdenun. Sitrface diffusizities weve sinzilav for iWo-0.0ZC and Mo-33Re. The presence of about 1 -?nm pressure of silver or tin vapor did not affect the neckanis)n of grooz;e formation. In liquid titz or silz:er, pain bolindary gvooves formed by zolume diffusion in the liquid. BASED on theories of ullins," the mechanisms of grain-boundary grooving have been determined for low-melting metals such as copper in an inert atmospheres or in liquid lead.4 The purpose of this investigation was to study grain-boundary grooving in the refractory Group VI-A metals, chromium, molybdenum, and tungsten, and the bcc solid-solution alloys, r-35e, 0-33e,= and -25e,' at 0.6 to 0.9 of included to see whether Mullins' theories were applicable to them as well. EXPERIMENTAL WORK The materials chromium, molybdenum, tungsten, Cr-35Re, Mo-33Re, and W-25Re were in the form of 0.050-cm-thick sheet assaying 99.98 pct or better. The nominal carbon level was generally 30 ppm. The oxygen + nitrogen + hydrogen content was -50 ppm. Mo-33Re and W-25Re were prepared by powder-metallurgy methods and supplied by Chase Brass and Copper Co. The remaining materials were arc-cast. Chromium and Cr-35Re were prepared at Battelle by arc melting, extruding, swaging, and rolling. Mo-0.003C was supplied by Climax Molybdenum Co., and Mo-0.02C and tungsten by Universal Cyclops Corp. As a source of liquid metals, tin and silver granules assaying 99.98 pct were used. Spectrographic analyses indicated the presence of -100 ppm each of iron and silicon. Vacuum melting reduced the combined gas content to c5 ppm (2.60,, 0.9N2, 0.4H2 in tin and l.602, 0.7N2, and c0.04H2 in silver). Specimens were prepared for grain-boundary grooving. Coupons 0.5 by 1.5 cm with a small hole in one end, or substrates 1.5 by 1.5 cm, were cut from sheet. The specimens were annealed in containers of the same material to provide a vapor-solid equilibrium as well as to protect them from gaseous impurities. Outgassing was done at 2 x 10"5 mm for 15 to 30 min at 1150°C for chromium and Cr-35Re, 1750°C for molybdenum and Mo-33Re, and 2600°C for tungsten and W-25Re. Then recrystallization to a stable grain size of about 0.5 mm was accomplished by annealing at least 1 hr at 1600°C for chromium, 1800°C for Cr-35Re, 2350°C for molybdenum, and 2300°C for Mo-33Re in a rhenium-element resistance furnace under 1 atm of static argon or helium. The atmosphere was gettered by tantalum radiation shielding. Tungsten and

Jan 1, 1967

By Don B. Shupe, John K. Berry

The handling and disposal of mine water is a much larger problem than is apparent at first glance. Many more tons of water are removed from underground coal mines in the United States each year than tons of coal. In the old anthracite region of Pennsylvania the average was around 32.7 t (36 st) of water for each ton of coal produced, while bituminous mines average about 4.5 or 5.4 t (5 or 6 st). Water encountered in the mines may come from several different sources. In mines with light cover and without a firm solid roof, rain may seep directly into the workings. This is also true of deeper mines where pillar falls have broken the roof to the surface. The top under creek beds is generally faulty and broken and water comes through the roof at this point. Deeper mines are frequently overlain by water-bearing strata and pillar breaks and faulty top can admit water, while places running to the dip often accumulate water which comes up through the bottom. In all cases, except where passing under a year-round stream, the amount of water made is usually pretty closely connected with the weather-more water during the rainy season, less in the dry, although the deeper a mine is, the longer it is before changes in rainfall are felt. Another source of water, not connected with seasonal changes, is old water, accumulated over a period of time in abandoned workings of the mine, or from flooded adjacent mines. Here the water filters through the coal, the parting, or comes up through cracks in the bottom. Similarly, core holes, drilled to prospect the property, can be a source of unexpected water and modern safety requirements for dust-allaying water at the working faces can turn a pleasant working area into a soggy mess over the weekend if the system is not properly maintained and operated. Why water must be disposed of is obvious. If allowed to accumulate, sooner or later the mine will fill up, or at least it will become "roofed" in low places, blocking ventilation and traffic. It must be controlled long before it reaches this stage. Water standing in the working faces is

Jan 1, 1981

By Don B. Shupe, John K. Berry

The handling and disposal of mine water is a much larger problem than is apparent at first glance. Many more tons of water are removed from underground coal mines in the United States each year than tons of coal. In the old anthracite region of Pennsylvania the average was around 32.7 t (36 st) of water for each ton of coal produced, while bituminous mines average about 4.5 or 5.4 t (5 or 6 st). Water encountered in the mines may come from several different sources. In mines with light cover and without a firm solid roof, rain may seep directly into the workings. This is also true of deeper mines where pillar falls have broken the roof to the surface. The top under creek beds is generally faulty and broken and water comes through the roof at this point. Deeper mines are frequently overlain by water-bearing strata and pillar breaks and faulty top can admit water, while places running to the dip often accumulate water which comes up through the bottom. In all cases, except where passing under a year-round stream, the amount of water made is usually pretty closely connected with the weather-more water during the rainy season, less in the dry, although the deeper a nine is, the longer it is before changes in rainfall are felt. Another source of water, not connected with seasonal changes, is old water, accumulated over a period of time in abandoned workings of the mine, or from flooded adjacent mines. Here the water filters through the coal, the parting, or comes up through cracks in the bottom. Similarly, core holes, drilled to prospect the property, can be a source of unexpected water and modern safety requirements for dust-allaying water at the working faces can turn a pleasant working area into a soggy mess over the weekend if the system is not properly maintained and operated. Why water must be disposed of is obvious. If allowed to accumulate, sooner or later the mine will fill up, or at least it will become "roofed" in low places, blocking ventilation and traffic. It must be controlled long before it reaches this stage. Water standing in the working faces is

Jan 1, 1981

By W. A. Backofen, G. Mayer

Single crystals of iron, copper, and a Cu-7 wt pct A1 alloy were pulled through conical dies to simulate the constraint in a polycrystalline aggregate undergoing axisymmetric reduction. With Taylor-type hardening, dependence of the drawing stress, od, on the Taylor orientation factor, M, is predictable from the polycrystal stress-strain curve; in particular, for a power-law relationship, it should follow that d log od/d log M = (1 + n). A first-order agreement with analysis was found in the data from iron. For copper, the implied n from the observed d log od/d l°g M was -0, while for Cu-7Al it was negative. The trend was in the direction of random polycrystal behavior. Thus the idea of hardening only in response to the amount of prior slip loses validity as stacking fault energy (SFE) is lowered. Two possible explanations have been suggested: as stacking fault ribbons are widened, barriers from dislocation reactions become increasingly effective in dispersing slip and reducing the orientation dependence of the total glide strain dm that appears in alternatively, or conjointly, the polyslip shear stress, 7, acquires an orientation dependence of a kind which has the same leveling effect on M. The problem of relating the strain hardening of polycrystalline material to that of an isolated single crystal is still largely unsolved. In a new experimental approach from recent work, single crystals of different orientations have been deformed under the constraints found in an aggregate while measuring their deformation resistance. Procedures have involved drawing cylindrical crystals through conical dies1 and compressing slab-shaped crystals in plane strain.2'3 Predictions for the outcome of such experiments were made first by Taylor~ and later, in more general form, by Bishop and Hill.5'6 Taylor's example was the axisymmetric extension of an fcc crystal slipping on the usual {111}(110) systems or, equivalently, a bcc crystal undergoing 'kestricted" slip on {110}(111). In his solution, the deformation work supplied was equated to that dissipated internally in slip on all active systems. With o the single applied tensile stress, dc the resulting axial strain, and dyT the total glide strain on systems operating at resolved shear stress, 7: The orientation dependence of M was found by minimizing dyT for each orientation while activating five independent systems, Fig. l(a).? The Bishop and Hill analysis, based on a principle of maximum work, leads to essentially the same conclusion; the need for at least five active systems is recognized in the finding that either six or eight are actually brought into operation. The mean value from the entire stereo-graphic triangle in either case is M - 3.06. More recently, Hutchinson8 made a Taylor-type analysis for pencil glide in a bcc structure, from which piehlerg prepared Fig. l(b) as the counterpart in Fig. l(a); here M = 2.75. The obvious weakness in such analyses is the indifference to slip-system interactions. A condition of what might be termed "independent"

Jan 1, 1969

By L. D. Jaffe, D. C. Buffum

EARLY papers1-' reported that temper brittleness is influenced by microstructure. This conclusion was based on room temperature impact tests, the inadequacy of which has been pointed out. Pellini and Queneau7 measured impact energy absorption at —80O to +25oC for several microstructures. On the basis of the shift, associated with temper brittleness, in the energy vs testing temperature curve they concluded that tempered martensite is somewhat more susceptible to temper brittleness than is tempered pearlite. The range of temperatures was insufficient to give complete curves covering the transition from tough to brittle behavior, so it is difficult to evaluate quantitatively the shift for the different microstructures. Also, the smaller shift of pearlite might be attributed to its already being temper embrittled at its temperature of formation. Accordingly, blanks 2 3/16 in. long were cut from a heat of SAE 3140 hot rolled steel barstock, 5/8 in. diameter, on which other work has been reported? A set of blanks was austenitized 1 hr at 900°c, water-quenched, tempered 16 hr at 675oC, and water-quenched, giving a microstructure of 100 pct

Jan 1, 1954

By Jose J. Alvarez

INTRODUCTION Three major plant processes control the operation of an uranium in-situ mining plant. The three pro- cesses can be categorized under the headings termed - loading, elution, and precipitation. All other plant processes can be subcategorized under the three. In summary, the major plant processes in an in- situ mining plant are: 1. Loading - The pregnant lixiviant from the production wells flows through anion exchange resin. The loading of the uranium on the resin is controlled by various factors, such as ionic strength, valence, functional groups, etc. 2. Elution - The uranium-loaded resin is eluted or regenerated by a high ionic strength solution. The effluent from this process is de- fined as the pregnant eluate. 3 . Precipitation - The pregnant eluate is chemically treated to attain the ideal conditions for the selective precipitation of uranium. Hydrogen peroxide is an ideal precipitating agent under URI conditions. This paper will focus on two of the major processes: Elution and Precipitation. For the most part this relatively young industry has grasped the theory of liquids in continuous flow for the operation of the plant processes. Likewise, URI initially operated the two processes of interest with the continuous flow concept. Through laboratory experiments, URI has abandoned the flow concept and operates the eluting and precipitating stages with the concept of "batch" processes, whereby only one container, filled to a specified liquid level, is chemically processed. In the proceeding sections, each of the two pro- cesses will be discussed in detail, from their original concept to the present operation. Only minor modifications were made to the existing circuits for the conversion with results revealing a greater level of efficiency. ELUTION The elution of the loaded anion exchange resin can be achieved by different high ionic strength solutions. The selection of constituents is dependent on both chemical and economic considerations (i .e., efficiency and operating/restoration factors). The regenerant presently used is a pH 9.5 solution containing 7.5% NaCl and a mixture of Na2C03/NaHC03. expressed as 2.5% NaHC03.

Jan 1, 1980

By G. W. Housner

The series of earthquakes in the vicinity of Koyna Dam in south- western India, which included a very damaging magnitude 6.5 shock on Dec. 11, 1967 (Dec. 10 GMT), is of much interest. The events are exceptionally well documented, which is a tribute to Indian geologists, seismologists, and engineers. To help in disseminating the information in the United States, this chapter presents a brief summary of the pertinent data and lists references. Koynanagar (Koynatown), which began as the construction camp for the dam, is located about 140 miles southeast of Bombay and 70 miles south of Poona at 17.4ºN and 73.7ºE, about 40 miles inland from the Arabian Sea. Koyna River flows almost due south from its source a distance of about 38 miles and then makes an abrupt turn to the east and travels some 480 miles to empty into the Bay of Bengal. Koyna Dam is located about 3 miles north of this turn. The approximately north-south trending continental divide is a few miles west of Koyna and the terrain drops steeply about 1700 ft to where the hydroelectric generating station is located. The reservoir behind Koyna Dam forms a long, narrow lake (Shiva- jisagar Lake) with mean water level (MWL) at 2160-ft elevation. The 345-sq-mile watershed receives an annual rainfall of about 200 in., most of which falls between mid-June and mid-October. The peak storage is 99 x l09 cu ft. A controlled flow passes under the continental divide in a tunnel and then down to the electric generating station about 5 miles WNW of the dam. The inflow not used for power generation is released to Koyna River. The Koyna project is a major source of electric power for Bombay and produces 540 MW at peak load.

Jan 1, 1970

By C. A. Heberlein

C. A. HEBERLEIN,* New York, N. Y.-The results stated by Rey and Brevers are so startling that they are of great interest, as the concentration of a low percentage of cinnabar by differential flotation yields a high-grade concentrate in the presence of either arsenical or iron pyrite. The authors say: "Cyanide can thus be used to depress arsenopyrite and make a good cinnabar-arsenopyrite separation. A cinnabarpyrite separation could probably be effected in the same way." Corrosive sublimate at the present price of mercury would be a very expensive reagent but the expense would be justifiable if a high rate of concentration could be obtained with a high extraction. On my request, special tests were made in the Punitaqui mill in Chile along the line suggested by the authors, without any improvement of either grade or extraction. As the recovery of the cinnabar in a complex sulphide of chalcopyrite and pyrite gave unsatisfactory results, I had tests made at the testing laboratory of the American Cyanamid Co. at Stamford, Conn. As these tests turned out to be highly satisfactory, not only at Stamford but later at the mine, they are presented here. [AMERICAN CYANAMID TEST FEED PER CENT Si02 66.54 A12032.08 CaO0.70 MgO 0.00 Alkalis1.78 Fe15.63 Cu0.44 S9.42 Hg0.45 OZ. PER TON Ag0.95 Au0.151 Screen Analysis of Tailings, Per Cent Plus650.0 Plus 1001.32 Plus 15020.75 Plus 20019.85 Minus 20058.08] The pulp had a density of 22 and a pH of 7.8. Total time of conditioning was one minute. The reagent added was Texas fuel oil, 0.116lb. Of 33.7 Bé. gravity containing 0.9 per cent sulphur. Frother, 0.062 lb. of No. 5 pine oil. Rate of concentration of mercury was 25.7: 1 [ ]

Jan 1, 1941

By Herbert Hoover

This paper is in the nature of a rough preliminary report on the progress that has been made in the application of the mass spectrometer to various problems arising in the petroleum industry. A few years ago the authors considered a number of the problems that were arising in the qualitative and quantitative measurement of small amounts of hydrocarbons. The methods available of making analyses by chemical techniques appeared to leave much room for improvement. Without going into the reasons at this point, attention was turned to the possibility of employing physical instead of chemical methods of accomplish-ing the desired results. A preliminary investigation disclosed that the mass spectrometer presented a possibility of solving many problems which could not easily be accomplished by other methods. Work was begun in developing the necessary apparatus and technique. A great deal of encouragement and many valuable suggestions were received from Dr. Robert A. Millikan, Dr. W. R. Smythe, and Dr. W. N. Lacey, of the California Institute of Technology, and from Dr. E. 0. Lawrence, who recently received the Nobel Prize, of the University of California. The authors particularly wish to acknowl-edge the very great willingness of these out-standing scientists to be helpful in solving many of the problems that were involved. So far as the authors are aware, this was the first application of the mass spectrometer to commercial work. The results were considerably better than had at first been anticipated. Briefly, it is pos-sible to run a qualitative and quantitative analysis of an unknown mixture of hydro-carbon gases, with an accuracy of better than plus or minus 5 per cent of each of the various constituents. An exceedingly high degree of sensitivity has been obtained, and a relatively short time is required to com-plete an analysis. Furthermore, it is un-necessary to separate a mixture of gases into its various components in order to complete the analysis.

Jan 1, 1940

By Richard V. Ageton

Salt bodies in the form of rolls, horses (sometimes called horsebacks), folds, wants and pinches1 have been encountered while driving entries and mining out rooms during the development of the potash mines in New Mexico. Superficially these sporadic salt occurrences appear to be much alike, but closer examination reveals individual characteristics, and after four years of observation it seems possible to divide them into three general groups that may tentatively be called "depositional," "erosional," and "structural." The data collected are not yet sufficient to permit forecasts of their probable location, so that the annoyance of having to mine salt instead of potash could be avoided or lessened. However, the information so far available appears to throw some light on the occurrence of the sylvite2 bed now being mined, and it is as a progress report that the writer presents the results of his observations. The mines of the United States Potash Co. and the Potash Company of America are about 20 miles northeast of Carlsbad, in Eddy County, N. M. They are on the southwestern flank of the Permian salt basin, which underlies western Texas, Oklahoma and Kansas, south-central Nebraska, southeastern Colorado and eastern New Mexico. The cuttings from many oil wells and the cores from the potash tests drilled in this basin indicate that this salt series approached its greatest thickness (about 4000 ft.) in the southeastern part of New Mexico and the adjoining portions of Texas, and that the most advanced stages of

Jan 1, 1938

By Richard V. Ageton

Salt bodies in the form of rolls, horses (sometimes called horsebacks), folds, wants and pinches1 have been encountered while driving entries and mining out rooms during the development of the potash mines in New Mexico. Superficially these sporadic salt occurrences appear to be much alike, but closer examination reveals individual characteristics, and after four years of observation it seems possible to divide them into three general groups that may tentatively be called "depositional," "erosional," and "structural." The data collected are not yet sufficient to permit forecasts of their probable location, so that the annoyance of having to mine salt instead of potash could be avoided or lessened. However, the information so far available appears to throw some light on the occurrence of the sylvite2 bed now being mined, and it is as a progress report that the writer presents the results of his observations. The mines of the United States Potash Co. and the Potash Company of America are about 20 miles northeast of Carlsbad, in Eddy County, N. M. They are on the southwestern flank of the Permian salt basin, which underlies western Texas, Oklahoma and Kansas, south-central Nebraska, southeastern Colorado and eastern New Mexico. The cuttings from many oil wells and the cores from the potash tests drilled in this basin indicate that this salt series approached its greatest thickness (about 4000 ft.) in the southeastern part of New Mexico and the adjoining portions of Texas, and that the most advanced stages of

Jan 1, 1938

By Harrison R. Cooper

With problems of diminishing ore grades and increasing cost of facilities, the mineral industry is acutely aware of the needs for improving beneficiation processes. Industry and universities are directing intensive technical effort to develop- ment of techniques with potential for using digital computers in automation and process analysis. The main problem of early attempts at on-line computer process control methods was that of economics. Now, with new advances in analysis and modeling making practical application economically important, it appears that minerals beneficiation is on the threshold of a significant jump in operating technology. In reviewing this work, particular note was taken of research and development applied to fundamental processes and the significant areas of effort where operations research techniques are used for process applications leading to the current state-of-the-art. Development of data automation and on-line control methods for process industries is deferred to the next section of this volume. This section deals with computer-facilitated mathematical-modeling development and reviews this work in conjunction with associated prior fundamental research leading to development of the methods. Flotation The 1960 state-of -the -art in flotation modeling was com- piled by Arbiter and Harris in the volume, 50th Anniversary of Froth Flotation, edited by Fuerstenau1. Many workers in the field of flotation initiated their research through flotation models, and this effort has led to use of simulation and operations re search methods employing computer techniques to facilitate advance of this work. The flotation model of Imaizumi and Inoue, published with supporting data in 1962, was expanded in 1968 with the objective of developing a basis for process automation.2,3 The fundamental work of Woodburn and Loveday in 1965 has led to techniques applicable to flotation circuit design optimization.4 This analysis is described in this volume by Woodburn in conjunction with King, Buchalter, and Piper. Niemi5,6 derived models for dynamics of a flotation circuit which were employed in developing a model describing

Jan 1, 1969

By Lo-Ching Chang, Kenneth M. Goldman

INTRODUCTION THE kinetics and mechanism of transfer of a constituent across a slag-metal interface are fundamentally important because many metallurgical processes involve the existence of a slag phase and a metal phase. Industrial processes seldom proceed to equilibrium, and information of the rates and modes of reactions are therefore often of greater practical importance than equilibrium data. A study of the kinetics of sulphur transfer across a slag-metal interface under reducing conditions will contribute a great deal toward a better understanding of desulphurization in the blast furnace process. The general principles existing in the transfer of a constituent, such as sulphur, across a slag-metal interface can be extended to similar transfer phenomena in other metallurgical processes. The present paper will demonstrate how such studies will lead to fruitful results from both the practical and theoretical standpoints. EXPERIMENTAL METHOD The apparatus used was simple. A graphite crucible 1 5/8-in. id, a wall 1/8-in. thick, and a depth of 4 in., was packed in an outer fused silica tube with powdered magnesia. The crucible assembly was rotated at a speed of 235 rpm inside an induction coil. A charge of 250 g of Armco ingot iron was introduced into the graphite crucible and melted by induction heating. The melt was held at a desired temperature [ ] for 3-5 min., after which 7.5 g of granular ferrous sulphide was added and the bath was held for another 3-5 min. A metal sample was then taken by means of a fused silica tube and a rubber suction bulb. Immediately after the metal sample was taken, 30 g of a prefused and crushed slag were introduced. The slag reached the temperature of the furnace in 1 to 1 1/ 2 min. Slag

Jan 1, 1948

By A. Rosen, P. Wynblatt, J. E. Dorn

The temperature, strain rate, and structure dependence of the flow stress in a poly crystalline Fe-2 pct Mn alloy was investigated between 77" and 370°K. It was possible to identify the low-temperature data from 77° to 160°K with Dorn and Rajnak's theory of the Peierls mechanism of plastic deformation. Above 160°K one or more thermally activated mechanisms must he operative; however, these were not identified in this investigation. The mechanistic basis for the rapid decrease in the flow stress of bcc metals with an increase in temperature over the low-temperature range is yet being debated. Various dislocation mechanisms have been suggested in the past but the agreement between the various proposed theories and the experimental results have not been definitive. In the present paper, the authors will demonstrate that the plastic behavior of polycrystalline iron containing 2 wt pct Mn plus interstitials agrees excellently with predictions based on the Peierls mechanism from 77" to 160°K whereas from 160" to about 370°K other as yet unidentified thermally activated mechanisms take over. Undoubtedly, the overlap of these mechanisms with the Peierls mechanism contributed to the difficulties of rationalizing the low-temperature behavior of iron and its alloys. I) EXPERIMENTAL TECHNIQUES AND RESULTS Although extensive data are now available on the effect of temperature and strain rate on the flow stress of various bcc metals and alloys, it was, nevertheless, deemed necessary for the objectives of the present study to obtain highly accurate data of the type most pertinent for checking the theories on a series of well-documented work-hardened states. Iron containing 2 wt pct Mn was used in this investigation in order to obtain a lower ductile to brittle transition temperature than that for iron.' The additional elements present were 0.004 pct C, 0.05 pct 0, 0.004 pct S, 0.003 pct P, 0.006 pct N, and 0.001 pct Si. The as-received 3/8 by 3/4 in. bars were cold-rolled to 0.100-in. thickness, recrystallized under argon for 30 min at 1073"~, further cold-rolled to 0.063-in. thickness, and finally recrystallized under argon for 30 min at 1000°K. This treatment gave a stable reproducible equiaxed grain structure having an average grain diameter of about 90 p. Prior to the final recrystallization treatment, the sheet was machined into tensile specimens 1/4 in. wide having a 1.625-in.-long gage section. All specimens were tested in controlled-temperature baths on an Instron Testing Machine. For convenience in the theoretical analyses the data will be given in terms of the shear stress for flow, 7, the shear strain rate, f, and the shear strain, y. A series of three standard strain-hardened states were obtained by prestraining specimens at 300°K and at a shear strain rate of 7.68 x lo-' per sec to three stress levels of 6.89 X l08, 10.3 X lo8, and 14.5 x 10' dynes per sq cm, respectively. Immediately following this prestrain the temperature bath was changed and each specimen was pulled in tension at either f = 7.68 X lo-' or f = 3.06 X 10"3 per sec. In terms of the accuracy that was achieved, the values obtained did not deviate more than *0.1 X 10' dynes per sq cm and * 1°K from the reported values of stress and temperature and not more than *5 pct in the reported values of the strain rate. The tensile stresses were converted to shear stresses using a factor of 1/2. The shear stress for the initiation of flow at the test temperature was determined by taking a y = 6.16 x 10'3 offset. from the modulus line at which point good accuracy could be achieved in determining y and the associated flow stress 7, with only a negligible increase in the pre-

Jan 1, 1965

Edward Dyer Peters, the only child of Henry Hunter Peters and Susan Barker Thaxter, was born in Dorchester, Mass., June 1, 1849. From his father he was a descendant of the Peters family of Ipswich and Andover, Mass., whose earliest ancestor settled in Essex County in 1659; while upon his mother's side he descended from several old Hingham families, as well as from the Quineys and from Governor Bradford. Between the ages of fourteen and sixteen he was a student at the Episcopal School for boys in Cheshire, Conn. Near the school was an old tin mine, and he used to spend his Saturday afternoons exploring it. When Edward was sixteen, his father sold his property in South-borough, and for the next three years lived in Europe. Sept. 26, 1865, Edward entered the Royal School of Mines at Freiberg, Saxony. In the summer of 1867 he joined his family on Lake Geneva, and spent a part of the season in that vicinity, going to Chamounix and taking other trips. Extract from a letter to his father: Elbingerode, Harz, Aug. 30, 1868: I left Freiberg with my friend Lilienthal, on Wednesday the 19th of August, reached Leipzig in the evening and spent the night in that city: the next morning we took the cars and in the afternoon reached Eisleben, in Prussia, which was to be our first stopping-place; there are immense copper-mines and smelting-works at this place, and the method of working the mines is very peculiar ... The next morning we got up at five and spent the whole day in the smelting-works where I obtained a number of drawings of the furnaces they use here and a good many valuable data. Saturday morning we got up at four o'clock, and descended a mine about three miles from the town; the Director of this mine was one of the most intelligent and agreeable men that I ever met; he accompanied us in the mine and explained everything that was new to us. The system of mining at Eisleben is peculiar to this town, and is not used at any other place in the world; the copper ore comes in narrow, flat veins eighteen inches high, at the utmost, consequently the men work lying flat on their left side and using the pick with both hands: the ore is carried out of the side passages into the main ones, in very low waggons about twelve inches high, and four by two feet; the boys who pull these waggons have a board buckled to their left thigh and their left arm; they pass their bare foot through a strap in the waggon and wriggle along on their side dragging the waggon after them, with their foot, almost as fast as a man can walk above ground. In the afternoon we walked over to Hittstadt, about twelve miles, and remained there Sunday and Monday. Monday night, at ten o'clock we went out to one of the smelting-works, to see the refining of the copper; this is only done at night, so we worked there from ten in the evening till eleven the next morning, and came home all blackened up and with blistered hands, for our skin was not quite so tough as that of the workmen: at noon the same day we took the stage to Ascherls-leben, and then the train to Stassfurt, where there are immense salt-mines, as well as factories for the manufacture of bromium, which latter process is, however, kept a profound secret, so we had very little hope of seeing anything but the salt mines; we were talking with our landlord about our disappointment, that evening, when he told us that the director of the Bromium works was sitting in the next room with no company but his glass of beer, so we went over to him, introduced ourselves as Americans, and actually succeeded in persuading him that it could do his business no earthly hurt if he showed us his works; at last he consented, after making us give our word of honor

Jan 1, 1919

By H. N. Eavenson

EaRly in 1917, the United States Coal & Coke Co. secured options on several tracts in Harlan County, Ky., aggregating about 19,000 acres in area, and after careful prospecting by outcrop openings and diamond drilling, completed the purchase late in July of that year. This property is situated in the eastern end of Harlan County, south of the Poor Fork of Cumberland River, and extending across Big Black Mountain to the Clover Fork of Cumberland River, a distance of about 7 mi. (11.3 kg.). It extends from the Kentucky-Virginia line westward for about 6 mi. Looney Creek, which empties into Poor Fork, crosses the property for about 4 mi. (6.4 kg.), and as several of the seams within the property outcrop along this stream, it afforded an easy, and the logical, place for development. The property is on the northern side of the geological trough formed by the uplifting of Stone Mountain, on the southern, and Pine Mountain, on the northern side; the northern boundary along Poor Fork is practically at the base of Pine Mountain. This area has been described in various geological reports. The main seam on this property is the one known variously as the "C," Benham, Keokee, Taggart, and Roda; it is also called, by the Kentucky Geological Survey, the Kellioka seam of the western portion of Harlan County. This seam averages, in this property, about 5 ft. (1.5 m.) in thickness, although local rolls reduce this thickness considerably over small areas, and at the extreme western end of the property the seam splits. It is usually clean, although occasionally a small parting occurs within a few inches of the bottom of the seam; it is one of the best coking and gas coals in the United States. The average analysis of this coal is given in Table 1.

Jan 1, 1922

By D. W. Fuerstenau

Measurement of zeta potentials is a useful tool to study the surface chemistry of minerals under flotation conditions. Because there is continued interest in this approach, the apparatus for obtaining zeta potentials of nonconducting solids by the streaming potential method is outlined here. Fig. 1 illustrates the streaming potential apparatus. The streaming potential cell or plug consists of two 24/40 standard ground joints (4) joined with a piece of pyrex tubing 60 mm long and 12 mm in diam (5). The electrodes are made of bright platinum disks 19 mm in diam and 1 mm thick through which 0.5-mm holes have been drilled (6). To the surface of each is welded a piece of 80-mesh platinum gauze. Each electrode is permanently mounted on the ends of the inner parts of the two standard joints by means of a platinum wire (7) which connects it to the tungsten seal at the end of the cell (8). For ease in cleaning and handling the apparatus, the streaming cell is fastened to the 500-ml reservoir flasks (1) by means of two 18/9 ball and socket joints (2). This particular arrangement permits passage of the solution in either direction through the plug of particles. Flow of solution can be stopped by a stopcock (3). One of the reservoir flasks has a large opening to permit insertion of either a thermometer or a pair of electrodes for measuring pH of solutions within the system. In making the experiments, the plug is filled with 48 to 65-mesh particles, but a layer of 28 to 35-mesh particles is placed at each electrode to prevent any of the finer particles from passing through holes in the electrodes.

Aug 1, 1956

By C. T. Eddy

The refining of native copper in the reverberatory furnace, as practiced in the Lake Superior district of Michigan, is very similar to the reverberatory melting and refining of cathodes, but the presence of arsenic in some of the copper concentrates renders the operation somewhat more difficult. Though the copper occurs as the native metal, which is often excep tionally pure—purer, in fact, than after it has undergone refining—its intimate association with the gangue minerals necessitates the cumbersome reverberatory treatment. The gangue consists chiefly of complex silicates of calcium, magnesium, iron, aluminum and sodium, but in certain ore deposits other minerals are often found, among them the native copper arsenides—mohawkite, whitneyite, algodonite and the like. These latter minerals, when present, because of their relatively high specific gravity (7.5 to 8.5), find their way into the concentrates through the gravity concentration processes employed in the recovery of the copper. When such concentrates are melted, the silicates are removed as slag, but, because of the great affinity of molten copper for arsenic, the arsenides dissolve more or less completely in the copper bath. Because of the stability of the resulting melt, the arsenic is tenaciously held in solution. The influence of arsenic on the properties of copper, especially on its electrical conductivity, is generally recognized. For certain uses it is beneficial, and in many instances its presence in limited amounts is not objectionable, but if the metal is to be used for electrical purposes, the almost complete removal of the arsenic is of prime importance. Considerable research has been done on the subject of the influence of arsenic on the electrical conductivity of copperll but the conclusions presented in the literature dealing with the problem show some disagreement. The methods now in use for the removal of arsenic have not

Jan 1, 1931

By Keats, J. L.

IN THE literature on the elimination of metalloids in basic open-hearth practice, there are a great many heats recorded in which excellent data on changes in slag and metal composition during refining are given, but in almost all of these heats either temperature data or weights and analysis of charge are unrecorded and observations on the physical charac- teristics of the slag are almost always lacking. With these points in mind, a test heat was made in which as complete as data possible on all the factors that affect the elimination of metalloids were obtained.

Jan 1, 1957