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By R. J. Grissom

PHOSPHATE deposits have been worked in many countries of central and south central Tennessee, but only ht ebrown rock deposits of Maury and Giles Counties will be discussed at any length in this articles, as all of the major opeations are now located there. They are: Mt. Pleasant District-Federal Chemical Co., Hoover and Mason Phosphae Co., International Minerals and Chemical Corp. (Maury and Giles Counties), Virginia-Carolina Chemical Corp. (formerly Charleston Mining Co.), and Victor Chemical Co. Columbia District-Armour Fertilizer Works and Monsanto Chemical Co. In the near future, the well-known, extensive deposits of blue rock in Lewis and Hickman Counties,also the brown rock in Hickman, Willamson, Summer and Davidson Counties, will again come into production. Certain physical peculiarities of the Tenessee deposit have played an important part in the design and use of mining and milling equipment.

Jan 1, 1944

By P. Martinez, A. F. Hoyte, F. E. Senftle

The possibility of applying a neutron activation technique for silver exploration is considered. A mobile positive-ion accelerator type neutron source is used to irradiate a small area of rock or soil in situ. By using a short period of irradiation and gamma ray spectral analysis, a technique is shown for silver exploration. Two different mobile units are described. Laboratory and preliminary field tests both indicate that a sensitivity of less than 1 oz of silver per ton of ore can be achieved. The increasing consumption of silver for industrial uses and also for coinage has caused a serious shortage of silver in this country. The silver shortage has been reviewed and analyzed by kiilsgaard1 who concludes that, "The best hope for meeting future demands for silver is through accelerated exploration for precious ores." As almost all the exposed "bonanza" type silver deposits evidently have been found, it is urgent that some sensitive geophysical technique be found to detect large, extended, but generally low-grade, secondary ores, as well as hidden vein deposits. Silver is easily made radioactive by exposure to slow neutrons; hence a neutron activation method appears promising for locating silver deposits. The principles of mineral beneficiation using neutron activation techniques were discussed some years ago.2-4 Using the same approach, a preliminary description5 has been published of neutron activation as a mineral exploration tool. An exploration technique is described in which silver is made radioactive in situ and detected with a gamma radiation counter. The technique is similar to the well-known method used for uranium exploration. THEORETICAL CONSIDERATIONS Elemental silver consists of two isotopes, Ag107 and Ag109, having naturally occurring isotopic abundances of 51.4% and 48.6%, respectively. For short periods of irradiation of silver by thermal neutrons, the long-lived 250 day, half-life isotope, Ag110m, is not produced in significant quantities. However, significant quantities of 2.3 min half-life Ag108 and 24.5 sec half-life Agl10 are formed by the following reactions. Ag108 and Agl10 emit a 0.44 Mev (million electron volts) and a 0.66 Mev gamma ray, respectively. Ag107 + n + Ag108 (2.3 min) Ag109 + n + Ag110 (24.5 sec). Because of the large capture cross section (110 barns) of Ag109, and short half-life of Ag110 (24.5 sec), the 0.66-Mev gamma ray is the most prominent emission from silver for neutron activation periods of about a minute's duration.* The 0.44-Mev gamma ray from Ag108 will also be present, but will be one or two orders of magnitude lower in intensity. The decay scheme of Ag110 is shown in Fig. 1. If the neutron irradiation time is limited to about 100 sec, the Ag110 activity will essentially reach saturation and can be used to detect the presence of silver. In a neutron flux of 10 8 neutrons/cm2/set, the induced 0.66-Mev activity in 1 g of silver will be about 2 x 107 disintegrations per sec. This is about 1000 times the measurable gamma activity of 1 g of uranium in equilibrium with all its decay products; hence there is ample activity for detection. Under the same conditions of activation, most of the other elements do not reach this relatively high disintegration rate. Although this is in favor of the proposed technique, other problems must be considered. For mobile operation, it is desirable to obtain the largest neutron flux to weight ratio. Hence we have used a small 150-kev accelerator-type neutron source rather than an isotopic source such as an americium-beryllium neutron source. By use of remote control system, an accelerator-type neutron source can be safely used without the massive shield required for an isotopic source. Moreover, an accelerator-type source is more versatile in that it allows one to use a flux of either 14-Mev or 3-Mev neutrons, depending on whether a tritium or a deuterium target is used. With a 14-Mev generator, one can obtain a flux of 10 9 neutrons/cm 2/sec, and with a 3-Mev generator, the flux is generally two orders of magnitude less. Although silver will become activated with either generator using proper moderation, detection may be

Jan 1, 1968

By James V. Thompson

SINCE it was introduced in 1943 to recover chromite from Oregon beach sands, the Humphreys spiral concentrator has proved successful in several fields of wet mineral beneficiation. By the end of 1957, 9390 Humphreys spirals had been manufactured. Most of these are still in service. The spiral does not offer a panacea for all mineral dressing problems. Its proper application can best be determined by test work. Spirals present a unique advantage for the metallurgist to make tests in a full-size machine rather than a miniature model, without the risk involved in scaling up results. With only 10 to 40 lb of sample, the operator of a closed circuit test unit employing a full-size Humphreys spiral can conduct preliminary tests with full-scale loadings of 0.5 to 2.5 tph. With larger samples, from 300 to 500 lb, he can run longer multi-stage tests to obtain reliable data for the next step-pilot plant design. The manufacturer of the Humphreys spiral concentrator maintains a fully equipped ore dressing laboratory and by insisting on test work prior to sales has largely prevented misapplication of the spiral.

Jan 1, 1958

By M. W. BERNEWITZ

ALTHOUGH many persons know that a lot of type metal and etchings are used in the U. S. Government Printing Office few would expect to find anything on metals in the annual report of the Public Printer, George H. Carter. Yet the report for the fiscal year ended June 30, 1931, contains many interesting items. For example: Among the 57,500,000 lb. of materials and supplies delivered to the printing office was little new metal, but the metal in circulation is 6,000,000 to 7,000,000 lb. In the cost of production $31,523 is charged against metal, nearly one-third for salaries and wages. In miscellaneous sales were $4,696 from waste metal and $1,147 from waste gold (from books). Electrotype and stereotype covered 11,438,314 sq. in. The vaults and storage rooms contain 1,700,000 plates and 130,000 pages of type containing 4,600,000 lb. of metal valued at $275,000. In what was known as the Congressional Globe vault were 46,000 stereotype plates; these were salvaged by remelting for other platemaking service. The Congressional Record superseded the Congressional Globe in 1873.)

Jan 1, 1932

By L. Adler

A fairly complex analysis is required to select or evaluate a piece of excavating and bulk handling equipment for its performance. At present, there is little agreement as to what points should be considered, and even less on what procedure to follow. This paper provides both of these in a consistent and direct form. The analysis applies to all types and sizes of equipment. The importance of the equipment characteristics, job activities, and work conditions are stressed. Separate analytical stems are established in a flow chart for these. They are combined using suitability tests in: problem statement; natural conditions; suitability guidelines; appropriate equipment types; operational activities; encumbered space; geometric design; equipment sizing; failure and limits; performance and consumption; public policy checks; and costs and profitability. Public policy and economics receive emphasis towards the end. The procedure is iterative, containing distinct feedback loops. Specifying the steps and sequence provides a necessary structure which has long been overdue.

Jan 1, 1985

By E. P. Sadowski, R. J. Raudebaugh

A study of micro structural characteristics of a 30 pct Cr, 42 pct Ni, 26 pct Fe alloy has been correlated with its behavior in creep and rupture tests at 1400°, 1600°, and 1800°F. Nitrogen pickup observed at 1600" and 1800°F was associated withfissur-ing of specimens prior to fracture. IN studying the high-temperature characteristics of a nominally 30 pct Cr, 42 pct Ni, 26 pct Fe alloy certain anomalies were observed, namely: The alloy had greater stress rupture and creep strength at 1800" than at 1600° F for time periods beyond 550 hr. As placed in test, this alloy was nonmagnetic. After test, some specimens were found to be fairly magnetic. The gain observed in magnetic response was not solely a function of time and temperature of testing. This is a report of the observations and a recounting of the results of studies made in an attempt to explain the behavior of the material under investigation. MATERIAL AND PROCEDURE All test material was taken from a production size heat of an experimental alloy melted and processed using commercial practice and having the following percentage composition: C Fe Cr Ni Ti 0.05 25.83 30.13 41.59 0.41 Al Mn Si S Cu 0.42 0.75 0.45 0.011 0.34 The material was tested in two conditions, namely mill-annealed and grain-coarsened. Mill annealing, which consisted of heating to about 1900° F in a continuous furnace for about 30 min and air cooling, gave a grain size of ASTM 8 and finer. To produce the grain-coarsened condition, mill-annealed material was soaked for 2 hr at 2050°F in a laboratory furnace and air cooled. This resulted in an ASTM grain size of 4 to 5. Rupture tests were carried out at 1400, 1600, and 1800° F in accordance with ASTM procedures. In tests where only rupture life and elongation at fracture were determined, specimens of 0.252 in. diam and 1 in. gage length were used. In tests where creep curves were obtained, specimens were of 0.375 in. diam and 4 in. gage length. Several of the tests under relatively low stress were discontinued short of rupture. Three low-stress tests are still in progress at this writing. Structural changes which occurred during testing were determined from examination of the tested specimens by light microscopy and X-ray diffraction. Diffraction pattern recordings were made with a diffractometer using copper radiation on samples heavily etched in a picric-hydrochloric

Jan 1, 1960

By Clemens Jones

A FORM of apparatus for volumetric determinations which shall possess the features requisite for the constant use of potassium permanganate, is a very desirable fixture in a well-appointed laboratory. Expedients to economize time and insure accuracy are generously employed for various other reagents, while the permanganate seems to have been consigned to the use of an ordinary burette, and a black bottle of the standardized solution. But the introduction of new, methods dependent on the permanganate, and the urgency of technical requirements where it has long been indispensable, require a revision of practice more scientific and convenient. The apparatus designed by the writer for the laboratory of the Thomas Iron Company at Hokendauqua, Pa., is so simply contrived and works with such entire satisfaction that a description of it may be of use. It may be prefaced that the characteristics of a suitable device offer some mechanical difficulties when combined in a continuous appliance. The burette, B (50 C.C. to 1/10 c.c.), shown in Fig. 1, consists of the graduated tube proper and an arm, E, fused to it below the 50 c.c. mark. At its top are rubber connections with the blast-aspirator, shown in the cut (Fig. 2) of the front view. By means of an extra stopcock, D, connection through E is established with the reservoir F. The burette is clamped Securely to a slide, C, which is counterpoised and moves freely on guides between two parallel sides, L, suitably

Jan 1, 1887

By Roy E. Gilbert

IN what ways can conventional geophysical methods be used in the search for quartz-sulphide veins covered by several feet of overburden? The New Park Mining Co., in search of an answer to this question, empirically tested simple geochemical, electrical, and magnetic methods over known ore bodies and geologic structures. Geochemical methods were the only ones found to be applicable to direct ore search. Indirect uses were found for electrical and magnetic tests. Experiments were conducted in the southeastern part of the Park City mining district. Ore in this part of the district is found principally in steeply dipping veins which are localized along faults and fractures that cut Paleozoic sediments and quartz diorite intrusives. Extensive soil cover effiectively hides both veins and country rock. The type of vein most likely to

Jan 1, 1953

By John W. Padan, John E. Crawford

Beginning with a small but positive participation in undersea mining, the Bureau of Mines continues its active investigations into this potentially tremendous field. The Bureau began its active role in undersea mining in September 1963, with a small task force of three dedicated scientists and a secretary, establishing headquarters at the old Tiburon Naval Net Depot about seven miles up the coast from San Francisco. The past months have been both busy and productive. With 22 Federal agencies involved in oceanography, it logically was the intent of Congress that the Bureau of Mines undertake research concerned only with the technology of marine mineral production and utilization. The Bureau has maintained this purpose in its activities at Tiburon, for while institutes, universities, the Navy and other Government agencies have developed exceptional programs in the fundamental science of the oceans, commonly called oceanographic research, little has been done toward advancing man's ability to exploit the ocean floors other than by drilling for oil and gas and sulfur.

Jan 3, 1965

GENERAL GEOLOGIC DESCRIPTION The mineral deposit of this case study can be described as a "typical" porphyry copper deposit of the southwestern USA and northern Mexico mineral province. The copper mineralization is related to Laramide age intrusives of intermediate composition which have been intruded into older, mostly crystalline, host rocks. Post Laramide deformation and faulting have subjected the deposit to erosion, leaching, and enrichment processes, which have created a secondarily enriched chalcocite zone. Later basin and range faulting down dropped the ore zone, resulting in deep burial beneath late Tertiary conglomerates and gravels, thus preserving the deposit from further erosion and oxidation. Lower grade chalcopyrite mineralization constitutes the primary zone underlying the enriched blanket. MANAGEMENT OF SAMPLE DATA Sample data were obtained from exploration diamond drill holes that were collared vertically and drilled with surface rigs. Most of the holes were surveyed downhole and found to deviate significantly from the vertical. The data were keypunched from original drill hole logs to formats as described in Chapter 6. Three types of cards were prepared: 1) A heading card containing the following information: [Project Name Coordi-in_ Hole Collarnates Bear-clina-Total ID Northing Easting Elevinglion Depth] 2) Individual record cards following each heading card with the following information: [SampleMin. Zone interval Assay Fields Leached (enriched ID From-ToTotal Cu Oxide Cu primary)] 3) Where downhole survey data were available, a card was punched for each downhole survey point. The card image looked very much like the heading card, followed immediately after the heading card, and contained the following information: [Hole Sur Point Sur Point Sur Point ID Bearing Inclination Depth] The keypunched data were then processed by the drill hole survey program producing a record file which contained information as follows: [Line 1. Project Name Date Assay Field Identifiers Line 2. Hole ID Northing Easting Elevation Bearing Inclination Number of Samples Line 3 through N+ 2 (where N equals the number of samples in the hole) Top Min. of Min. Zone Zone Sample Sample Coordinates Sample Assays Leach InterLength Northing Fasting Elev Total Cu Oxide Cu (etc) face] MINERAL BOUNDARY PROBLEM AND TREATMENT According to the geologic description, at least three mineral zones are present within the ore limits, as well as fault boundaries and a buried topographic surface, each of which have to be considered. The interfaces of the various mineralogical and geological boundaries were identified as accurately as possible in each drill hole by the project geologist, the location of the interface was surveyed in the computer program in association with the nearest sample intercept to the interface (note last field of line 3). Thus, the boundary is represented as a point in 3D space at each intersecting drill hole. The linear interpolation (LINTERP) program then searched the last field of the surveyed record to find the top of each mineral zone, or geologic boundary, and read the coordinates associated with that sample point. The program then used the coordinates to compute an interpolated surface between all existing data points as described in Chapter 11. A contour map was plotted for each of the computed surfaces and reviewed by the project geologist. Where the surfaces were poorly defined due to lack of real drill hole information, the geologist, at times, inserted a "pseudo" drill hole intercept according to his best judgment and feeling for the configuration of the surface, and such points were entered into the data stream for LINTERP. When the project geologists were satisfied that they had obtained

Jan 1, 1980

By A. E. Dwight

Lattice parameters were determined for eighteen equiatornic alloys of the CsCl-type structure, ten of which were previously un-reported. It was found that fomation of the CsCl-type structure in binary alloys of the transition elements is largely dependent on position of the elements in the periodic table. The relative size of the two elements was not found to be a controlling factor. A recent paper by Beck, Darby, and Arora1 corre-lates the occurrence of CsC1-type ordered structures with the position of the constituent elements in the periodic table for the first long period. It was also suggested that a definite increase in relative bond strength between unlike atoms occurred when, in binary alloys of iron-group elements, the other component is changed from a chromium-group element, to a vanadium-group element, to titanium. A later paper by Philip and Beck2 noted that the lattice contraction increased in the order CrFe, VFe, and TiFe. It was also noted by Philip and Beck2 that the lattice contractions of CsC1-type alloys decreased in the order: TiFe, TiCo, and TiNi, which is an apparent reversal of the contractions expected from the position in the periodic table. It was suggested that the increasing lattice contraction is an indication of increased stability, i.e., greater A-Bbond strength. The present investigation was carried out to determine whether the relation of the position in the periodic table to the formation of the CsC1-type structure was also correct for alloys involving the second and third long-period elements. A systematic search was made for CsC1-type structures among equiatomic alloys and for those found, the lattice contraction was determined. EXPERIMENTAL TECHNIQUE The elements Y, Gd, Ti, Zr, Hf, V, and Cb are designated the A group and the elements Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, and Au are designated the B group. Equiatomic alloys were prepared for 57 AB combinations. The alloys were arc melted in a multicrucible furnace3 in buttons ranging from 5 to 20 g. Chemical analyses were not made, as the charge weights agreed closely with those of the buttons after melting. The alloy buttons were homogenized at 800° to 900°C. Metal log raphic and X-ray specimens were prepared and heat treated at temperatures from 600° to 1200°C. Specimens for X-ray diffraction were usually ground to a powder in an agate mortar; however, needle-shaped solid specimens were used when the alloy was sufficiently ductile to permit their preparation. Diffraction patterns were taken with a Straumanistype Debye-Scherrer camera using filtered Cu or Co radiation. The lattice parameters were obtained in A by plotting the calculated a0 values against the cos29/sin 0 + cos2?/? function and extrapolating linearly to ?= 900. Metallographic control specimens were polished on cloth wheels with diamond paste and etched with various phosphoric and nitric acid reagents. RESULTS The eighteen equiatomic alloys listed in Table I gave evidence of a cubic structure with two atoms in the unit cell, although two of these cubic structures exist only at elevated temperatures and transform to a tetragonal structure on quenching. Nine of these eighteen alloys gave diffraction patterns with super-lattice lines showing that the structure is of the CsC1-type. The lack of superlattice lines in patterns of the other nine alloys may be attributed to the small difference in atomic scattering power of the components. Metallographic study indicates the occurrence of nine narrow single-phase fields at the AB composition. Any or all of these nine may also have a CsC1-type structure. The VFe alloy was found to have a CsCl-type structure by Philip and Beck2 through the use of CrKa radiation (for which the scattering factor of V is anomalously low), whereas the Cu radiation used

Jan 1, 1960

By P. A. Boeck

(San Francisco Meeting, September, 1915) THE thermal insulation of high-temperature equipment for industrial purposes is a subject that has not received from engineers and designers the attention its importance deserves. This may be attributed to a number of causes: In the first place, heat flow is a rather difficult factor to measure under the working conditions of an industrial furnace, and until the comparatively recent introduction into certain operations of the heat balance sheet, with a systematic attempt to account for the discrepancies in the totals, the various causes of heat losses and the reasons for their existence were not brought to light. Moreover, such rapid advancement and radical changes in the design of equipment, especially in metallurgical lines, have occurred that practice has apparently outdistanced the theory of design. In the modern tendency toward greatly increased size of units, effort has seemingly been made to utilize the heat of fuel gases without proper. attention having been paid to conserving heat energy and confining it strictly to the points of maximum activity. The systematic study of the thermal properties of structural materials, which is being carried out by various government bureaus and also by a number of technical societies, is forming the basis for more intelligent and consistent work in the economically important subject of prevention of fuel waste.

Jan 8, 1915

By B. J. Harlan

The trying times experienced by the steel industry during the past four years have emphasized the necessity of producing pig iron at the lowest possible cost. The trend in both design and operation of blast furnaces has been toward this end rather than toward securing maximum production from a unit or group of units. In the following discussion the trend in design of stacks and auxiliary equipment will be taken up before operation is considered. Although few furnaces have been constructed in the past few years, the trend is definitely toward larger furnaces with a hearth diameter of 24 or 25 ft. Such a furnace is very flexible, being able to produce efficiently any desired daily tonnage between 500 and-1000 or more. The detail of the design of furnace stacks, with the exception of the top, has changed little in recent years. To decrease the velocity of gas through the throat of the furnaces, thereby reducing flue-dust losses, the stock-line areas are constantly being made larger. The top dimensions of the larger furnaces are usually as follows: Stock-line diameter, 19 to 20 ft.; large bell diameter, 14 to 15 ft.; straight section of throat, 5 to 10 ft. high; inwall batter, 1 to 11/4 in. Pe ft. The ratio between the area of the stock line and the area of the large. bell is usually about 1.85 to 1. The stock-line diameter of some smaller furnaces has been increased to that of the hearth diameter of the stack at the expense of the stack batter. Remarkable decreases in flue-dust production are claimed for the so-called " Venturi top," which is achieved by flaring the stock line, in the form of an inverted cone, from a diameter of 17 ft. at 10 ft. below the large bell closed to a diameter of 19 ft. 6 in. at 3 ft. below the large bell closed. Time alone will tell which of the two designs is the better. Because of differences in raw materials, one top may be better for some plants and the other top for other plants. In the search for lower costs and higher efficiencies all operators are, adopting stoves that will maintain maximum hot-blast temperatures with a minimum gas consumption. To meet these requirements, stove capacity of approximately 7 sq. ft. of heating surface and 1.8 cu. ft. of brick volume is required per cubic foot of wind blown per minute.

Jan 1, 1934

By R. L. Manegold

IN RECENT years there has been a decided trend toward bringing ores and coal out of open-pit and underground mines by long, sloping single-stage belt conveyors. Because the high investment cost of haulage conveyors dictates maximum speed and full loading for economy, conveyor belts are running faster than ever before, with a greater burden on the belts. In addition, larger blocks of ore are being mined and conveyed. Rougher use of large mining equipment generates more tramp iron; mechanical loading rejects nothing. Therefore the extraction of tramp iron and other deleterious materials for the protection of haulage conveyors at transfer points, chutes, and idlers is becoming an increasingly difficult job. In our experience, the best method of protecting long haulage conveyor belts is to extract the tramp iron, at least the large tramp iron, ahead of the main haulage conveyor or series of conveyors. It is most practical to collect the tramp iron at the earliest source -possible, usually directly after the primary car unloading dump or after the primary crushers, which are ordinarily not affected by tramp iron, see Fig. 1. The coal or ore from its primary source is fed by chutes or feeders onto a buffer or shock belt conveyor, a short, ruggedly built conveyor system that can be considered somewhat expendable. Its primary function is to bring the ore up to speed for transmission to the haulage conveyor. There is no assured method of protecting this conveyor from tramp iron damage at its feed end. Likewise, there is a possibility, although remote if the magnet applied to this belt is installed correctly, that the tramp iron extraction process will damage the shock belt, which is, however, short and comparatively inexpensive. Magnetic head pulleys with their maximum effective range of about 8 or 10. in. cannot be considered for large installations, even though they are desirable because of the continuous and, automatic tramp, iron removal feature. Further, the most dangerous form of tramp iron with respect to potential damage to a haulage conveyor is the long rod, roof bolt, or rail segment, which is not extracted satisfactorily because of the limited tangential contact of such an iron shape with the magnet. Magnetic head pulleys are also undesirable because the dribble or fines from the head pulley discharge at the same point as the tramp iron. Screens must be used to separate the fines from the magnetics, resulting in additional expense and loss of head room. Magnetic detectors have been used with success, but they only indicate the, presence of iron, and the conveyor belt must be stopped for its manual removal. The, stoppage of any conveyor means that all preceding equipment must be stopped or a cascade of material on the idle conveyor will result. Occasionally combinations of detectors and magnetic, head pulleys are used. The detector precedes the magnetic head pulley and detects only large pieces of tramp iron, while the magnetic pulley subsequently takes out the smaller ferrous metals. Suspended magnets overcome the disadvantages of magnetic head pulleys, detectors or a combination of both. There are several magnetic extraction problems involved in applying a suspended magnet at this

Jan 1, 1952

By J. R. Linney

Demand for eastern magnetite in 1948 necessitated practically all eastern magnetite industries to operate on a six-day week, with the result that over 11,000,000 long tons of crude ore were mined, and the shipping products amounted to approximately 5,000,. 000 long tons. Reports indicate that operating on a six-day week and doing maintenance work on the seventh day was satisfactory and resulted in excellent continuity of operation. In the Port Henry district, Republic Steel Corp. once again set new all-time records for the production of crude ore and total shipping product; 1,868,000 long tons of crude ore were mined, 945,000 from the Old Bed mine, 408,500 from the Harmony mine, and 514,500 from the Fisher Hill mine. Of the 969,000 long tons of shipping products, 663,800 long tons were sinter, 181,000 lump ore, and 115,200 con¬centrates.

Jan 1, 1949

By J. D. Embury, R. M. Fisher, A. S. Keh

An investigation of the defect structure and properties following large strain deformation has been carried out using transmission electron microscopy and mechanical testing for a range of ferrous materials and for copper. It is shown that, for a variety of ferrous materials, a cellular substructure is developed during the initial stages of working and on further deformation the dimensions of this substructure are reduced. Quantitative measurements of the flow stress and the scale of the substructure indicate that the strength of heavily worked materials is largely determined by the spacing of cell walls. These cell walls act as dislocation barriers in a manner analogous to grain boundaries. FCC materials do not harden as extensively as bcc after cold working and the present observations on copper indicate that the dimensions of the substructure in fcc materials are not markedly reduced on deformation. The differences between the fcc and bcc structures produced by large plastic strains are ascribed to differences in the extent of dynamic recovery. It is tentatively proposed that the greater stability of substructural barriers in bcc structures results from strong interstitial Pinning effects. It is proposed that for large plastic strains the work-hardening process may be considered in terms of the reduction of substructural-barrier spacing during the working process. This pvovides a simplified hut useful analysis of the strain hardening occurring during mechanical processes. THE mechanisms of strain-hardening processes have occupied the attention of numerous investigators over the past three decades and a multitude of theories have emerged in this field. The majority of previous work has been concerned with the development of a description of the plastic behavior of single crystals in terms of dislocation theory.'" In contrast, scant attention has been given to the strengthening mechanisms operative during mechanical working processes such as rolling and drawing. The large plastic strains involved in these processes make it difficult to correlate the observations with any elementary dislocation theory. Further, as Bullen and coworkers3 have opined, for large plastic strains both hardening and recovery occur simultaneously and thus it is extremely difficult to estimate the effect of plastic strain on the ambient internal stress field. It is probable that for large plas- tic strains any theoretical estimate of the internal stress field must be made in terms of complex dislocation groups. Although some valuable theoretical work has been done toward calculating the elastic properties of dislocation groups4 any detailed self-consistent model for large plastic strain is as yet impossible. With these limitations in view it is still of value to examine the mechanical properties of highly strained materials as a function of their substructure. This relationship is explored in the present communication for a variety of materials subjected to rolling, drawing, or swaging. The primary object of this investigation has been to establish the validity and the limitations of the substructural strengthening mechanism proposed by Embury and eisher' for drawn pearlitic wire and by Meieran and Thomas for drawn tungsten wire. No attempt has been made to delineate the basic interaction mechanism which occurs between a slip dislocation and the substructure and the authors believe that a great deal more experimental evidence must be compiled before these fundamental aspects can be explored. Also, no specific attention has been given to the detailed formation of substructure during working. Experimental Details. A variety of materials were used in this investigation, the compositions and heat treatment of which are tabulated in Table I. The commercially pure iron is referred to throughout this report as Ferrovac E. The mechanical working processes were all performed at room temperature. The wire drawing was performed on a manual drawing bench. Reductions of between 10 and 20 pct in area per pass were used in both swaging and drawing. The experimental parameter used to evaluate the mechanical properties of the materials was the 0.2 pct proof stress. This was determined for wire samples using an Instron tensile machine at a crosshead speed of 0.02 in. per min. The techniques for preparation of samples for transmission electron microscopy have been described previo~sl~.~ Specimens from wire samples were prepared from longitudinal sections and in some cases from transverse sections. To evaluate the substructural characteristics of rolled materials, thin foil samples were prepared of both the face and edge sections. Results. One of the more familiar ways of expressing work hardening in mechanical working is by the flow stress as a function of reduction in cross-sectional area. Fig. 1 shows such a plot for Ferrovac E eutectoid carbon steel and for copper. The curve for Ferrovac E is characterized by an initial stage of rapid work hardening and a final stage of rapid work hardening separated by an intermediate stage with a low rate of work hardening. This behavior is typical of many ferrous materials and the drawn pearlite wire previously investigated by Embury and Fisher is a more pronounced example. Copper shows an initial

Jan 1, 1967

By C. R. Austin

THE investigation described in this paper deals with the development of high-temperature alloys of the Konel series over a considerable period of time at the Research Laboratories of the Westinghouse Electric and Manufacturing Co. The word "Konel" has been coined to designate a class of alloys which are essentially nickel-cobalt-iron with other elements added, usually in small quantities. Most of these alloys contain titanium, usually about 2.5 percent. The main consideration related to strength at high temperatures but the thermionic characteristics of the alloys was also of considerable importance. It is, however, with the mechanical properties at elevated temperatures that we are herein concerned. Much attention has also been devoted to their age-hardening characteristics. There is little need to stress the utilitarian aspect of this subject, as it has been discussed frequently. Alloys exhibiting superior properties at normal or elevated temperatures rapidly find many suitable applications. There may be some question, however, as to what constitutes a "superior alloy, " or an alloy that may have good service possibilities at high temperatures. The problem is complex and various means have been employed to predict the useful life that may be expected of a material. In recent years the "creep limit" has been used as the best means of evaluation. Such tests necessarily are prolonged and hence collection of data is very slow. In a general survey of many alloys therefore the creep test is not desirable and recourse must be had to much shorter time tests in order more rapidly to select alloys which appear to show promise. For this reason the present survey has been made using the high-temperature tensile test and a bend' test developed by Howard Scott.1 In the tensile test the conditions have been standardized for all tests, so that values obtained are at least comparable, one alloy with another, although the absolute values recorded merely indicate the mechanical properties at the given temperature under a definite rate of loading.

Jan 1, 1931

By Sidney Fischler

Large striation-free single crystals of bismuth have been grown from the melt by rapid freezing. Zone-refined bismuth, together with doping impurities if desired, is placed in a shallow flat-bottomed graphite boat and melted in air with a propane hand torch. The torch is then withdrawn in a manner which causes the melt to freeze direction-ally. Crystallization, which resuires only a few minutes, usually results in the formation of a single crystal even when a seed crystal is not used. Crys -tals of any desired orientation may be grown by using oriented seeds. Undoped crystals grown by this method have residual resistivity ratios greater than 200. THE growth of large single crystals of bismuth by either the Czochralski or horizontal zoning technique is not entirely satisfactory. Specifically, difficulties are encountered in producing single crystals of the required dimensions in all desired orientations, and striations caused by low-angle polysynthetic twins are frequently present in the crystals. In addition, both methods are time-consuming and require special apparatus of some complexity. A simpler method has now been developed for growing large striation-free bismuth single crystals of desired orientation in a short time. Fig. 1 shows a typical setup consisting of a rectangular graphite boat which contains zone-refined bismuth, a 1/8-in.-thick flat quartz plate which covers the entire inner bottom of the boat, and three additional quartz plates about 1/4 in. thick which are used to separate the bismuth from the graphite everywhere except at a small area at the left of the boat. The graphite boat is 1 in. high, and its sides and bottom are about 1/8 in. thick. The quartz plates should be smooth and clean. The graphite boat is heated from the right with a propane torch, as shown in Fig. 1, until the bismuth is completely melted. The melt has the shape of a triangle with a narrow neck at the apex farthest from the torch. The melt is frozen direc-tionally by gradually moving the torch toward the right, away from the boat. The bismuth in contact with the graphite, at the left end of the neck, freezes first. The freezing interface then moves down the neck into the main bulk of material, where it develops a convex shape ideal for the continuation of single-crystal growth. The interface continues to move through the melt until the entire bulk is solid. The entire procedure may be completed, in air, in a matter of minutes. The technique described almost always yields a single crystal whose basal plane is nearly perpendi,cular to the bottom of the graphite boat. In earlier experiments, in which the bottom of the melt was in direct contact with the graphite boat, single crystals were grown with basal planes parallel, perpendicular, or at some intermediate angle to the bottom of the boat. At times the orientation of the bulk of the material differed from the orientation of the material in the narrow neck. In these cases, a nucleation site initiated the growth of a differently oriented crystal, and the thermal conditions favored the new orientation over the initial one. The thermal conditions depend on a number of factors, including the heating technique, the placement, shape, and thickness of the quartz plates, the thickness of the walls and bottom of the graphite boat, and the quantity of bulk bismuth employed. All of these factors, plus the initial orientation and the presence and effectiveness of nucleation sites, will determine the orientation of the final large single-crystal slab. When a crystal of specific orientation is desired, an oriented section of a rapid-freeze crystal is shaped by spark cutting and grinding for use as a seed. To grow a doped crystal, the desired impurity is placed in the graphite boat together with the bismuth chunks and seed. Crystals doped with mercury, cadmium, lead, and selenium have been grown. The rate of freezing is so great that the distribution coefficient of any impurity approximates unity. On a gross scale, therefore, impurities should be more homogeneously distributed in rapid-freeze crystals than in Czochralski or zoned crystals. Because of the possibility of constitutional supercooling, however, it is quite possible that impurities are not homogeneously distributed on a microscopic scale in the rapid-freeze crystals. Generally the single crystal slabs which have been prepared are initially 5 to 7 mm thick. Thicker crystals may be obtained by using one of these slabs as a seed. The slab is placed in a graphite boat resting on a large aluminum block, either air- or

Jan 1, 1964

By John G. Bartram

The oil business has been relatively quiet in Wyoming during 1934. Only 34 producing wells were completed, 54 dry holes were drilled, and at the end of the year only 30 wells are listed as drilling. Wyoming still has a large reserve of production shut in, mostly in black oil or asphaltic base fields in the northwestern part of the state. The total oil production increased from 11,171,500 bbl. in 1933 to 12,539,470 in 1934, but light oil production continued to decline, and the increase was made by black oil fields. This is partly due to natural decline of light oil fields, especially Salt Creek, Big Muddy and Lost Soldier, but largely because of increased demands for road oil. The Rocky Mountain states spent much money to build and improve roads and a greater amount of road oil was used. The refining of black oil to manufacture road oil produced gasoline as a byproduct that slightly decreased the demand for light oil. The Oregon Basin and Frannie fields, in the Big Horn Basin, moved into second and third places in the list of producing fields in Wyoming because of their increased black oil production, and Big Muddy and Lost Soldier, light oil fields, dropped back. Wyoming stayed close to its allowed production, which was based on the needs of the refiners and purchasers. This activity in black oil resulted in a few more wells in the fields of the Big Horn Basin, but the greatest amount of drilling was in the shallow Osage field in eastern Wyoming. Osage supplies many little topping plants and at the close of 1934 there was not enough oil available there to supply all of them. In the Lost Soldier field and Salt Creek, one major company was rather active in a campaign to deepen, clean out and repair old wells to increase production, and the figures of that work are not included here. Of the light oil fields, Lance Creek promises to be most active during 1935, since the two wells in the recently discovered Sundance sand pool are producing and more wells will he drilled. With wildcatting almost at a standstill, two new oil fields were discovered in Wyoming in 1934. In Albany County, a 75-bbl. oil well was completed on Quealey dome in the Muddy sand (Upper Cretaceous)

Jan 1, 1935

By Grover J. Holt

IN order to provide a clear picture of the development of the sink-and-float process of concentration as applied to the iron ores of Minnesota, a few pertinent facts should be brought out concerning the ores and the products of concentration. Iron ore is primarily a cheap commodity handled in immense quantities. The price of iron ore at present, based on a natural iron content of 51.5 per cent, varies from $2.55 to $2.70 per gross ton f.o.b. cars at the mine or washing plant in Minnesota. Last year 92,000,000 gross tons were shipped from the Lake Superior district (Minnesota, Michigan, and Wisconsin) to the furnaces. Concentrated iron ores have no greater value per unit of iron content than ores that can be mined and shipped direct from the shafts or open pits. For years only the higher grades of concentrating ores could be treated and sold in competition with the immense reserves of direct shipping ore available. These higher-grade "straight wash" ores required only the simplest treatment; namely, the washing out of fine sand from coarse ore particles. As the exhaustion of the "straight wash" ore is reached, rock is found replacing part of this sand, and the ore no longer responds to the former sizing treatment. Substantial tonnages of this marginal (jig ore) remained to be treated. Because of the limitations placed on concentrates by the furnaces-namely, low price of product and minimum amount of fines-iron-ore concentration has been and must continue to be a one-pass process. Only an increase in price or a change in structure of concentrates allowed by the ore consumer will encourage departure from this practice. Faced with the necessity of handling large tonnages, with the limitations mentioned, iron-ore research men have found their search for new and more efficient methods of treatment seriously handicapped and removed from the field of fine crushing. Sink-and-float treatment appeared to offer the best field in coarse concentration and has been proved by several plants to be well adapted to our problem. The use of ferrosilicon as a medium solid was decided upon. In our present practice, the ferrosilicon metal, carrying about 83 per cent iron, 15 per cent silicon and 2 per cent carbon and nonmagnetics, is crushed to pass 65 mesh and used without further sizing. When mixed with water the specific gravity of the medium may be controlled to within 0.02 per cent above or below the required gravity. Table I shows examples of a change in solid content of the medium for varying gravities. [ ] Table I is based on clean ferrosilicon, whereas some contamination is always present in the mill circuit, tending to

Jan 1, 1943