Search Documents

By G. R. Pickett

Examples are presented which show that the velocity~ amplitude, attenuation and apparent frequency of several acoustic waves can be recorded in the borehole. Examination of such recordings, termed "character" logs, indicates that the wave types observed include a refracted compressional wave and a wave which travels with formation shear velocity. Laboratory data are used to show that compressional and shear wave velocities are dependent on porosity, effective stress and lithology; but that the change in reciprocal velocity per unit change in porosity is larger for shear waves than for compressional waves. We, therefore, conclude that. the accuracy of porosity determinations can sometimes be improved by use of shear wave velocities, provided that the shear wave amplitudes are large enough to delineate the shear arrival from the preceding compressional arrival on the character log. Borehole data are presented which show that the difference between shear wave and compressional wave reciprocal velocities can be used to predict porosities. This is a refinement which may allow the prediction of porosities from single-receiver acoustic logs without introduction of errors from borehole fluid traveltimes. Laboratory and field data are presented to show that the relationship between compressional and shear wave velocities can be used to indicate lithology. An example is presented to show that fractures usually cause a greater reduction in borehole shear wave amplitudes than in compressional wave amplitudes, an effect which may offer a more reliable means of detecting fractures. The complexity of the borehole acoustic wave train can rake presently available cement bond logs highly sensitive to the gate and bias settings used. The character log offers a means to circumvent possible misinterpretations by recording all amplitudes, from which the interpreter can select the appropriate data for evaluating the cement bond. Character logs may also be used as a quality control for open-hole transit-time logs when existence of small compressional wave amplitudes interferes with the proper functioning of bias-controlled timing devices. Evaluation of the potential uses of character log data is not complete; but a character log presented in a form convenient for routine use would be a desirable addition to currently available logs. To summarize, possible applications for such a log in formation evaluation include the following (1) quality control of transit-time logs, (2) refinement of porosity predictions, (3) determination of lithology, (4) improvement of fracture detection and (5) improvement of cement bond evaluation. Suggestions are made regarding the requirements for a suficient but practical character log for routine use. INTRODUCTION Acoustic logs have become a widely used porosity tool in formation evaluation. In addition, there is a growing application of acoustic logs in cement bond evaluation and fracture detection. These applications have mainly involved the use of logs of first-arrival transit times and amplitudes and have not included detailed studies of the complete signal. The purpose of this paper is to show that significant benefits in formation evaluation can be gained by a more complete use of the acoustic wave train generated in the borehole by an acoustic logging tool. We hope that this discussion will also stimulate further development of logs suitable for routine use so that these benefits may be realized. Examples of acoustic wave train logs, termed "character" logs, are presented to show that several identifiable acoustic waves are present in the borehole. The measurable characteristics of these acoustic waves and some of their relations to formation properties of interest are also discussed. The more obvious potential uses of character logs are listed, and some suggestions are made regarding the requirements for a sufficient but practical character log for routine use. CHARACTER LOGS Some 10 years ago, Vogel' and Summers and Broding' noted that the signals received uphole from an acoustic logging tool located in a borehole had a number of interesting characteristics. The logging tool consisted of two or more pressure transducers spaced on an acoustically insulated body (Fig. la). One of the pressure transducers was used as a transmitter to generate pressure waves in the borehole fluid. The other transducer served as a receiver to detect any pressure waves reaching it in the borehole. The receiver then converted these pressure waves to electrical signals which were transmitted to the surface and displayed on an oscilloscope as a record of time vs receiver-signal amplitude. Fig. lb is a schematic representation of a typical record. The interesting characteristics seen in the earlier' and subsequent experiments were (1)

By T. Sterry Hunt

SINCE: the date of my previous paper on this subject, presented at the Cincinnati Meeting, February, 1881, and published in our Transactions, vol. xii., p. 459, I have had occasion to revisit the Canadian apatite region, and to collect further data concerning its geognosy, which I hope to describe at a future time. At present, I shall put on record a few brief observations concerning the more recent operations in apatite-mining in the Lievre district, to the north of the Ottawa River, where the mines are as yet confined to a small area in the townships of Buckingham, Portland, Templeton, and Darry; the earlier workings having been along the Rideau Canal, to the south of the Ottawa. The large mining operations lately undertaken in the Lièvre district show that the crystalline phosphate of lime or apatite belongs to lodes of great size, which traverse the ancient gneiss of the region. These lodes include a granitoid feldspathic rock, and a pyroxene rock, with large masses of quartz, of carbonate of lime, of pyrites, and of apatite. All of these often show a banded structure, riot unlike that of the gneiss, to which they- are evidently posterior, arid of which they

Jan 1, 1886

By E. S. Bardwell

THE reverberatory copper-refining furnaces at the Great Falls Reduction Dept. of the Anaconda Copper Mining Co. have used successively, as fuel, lump coal on grates, pulverized coal, oil and natural gas. In no other plant, so far as can be ascertained, has such a variety of fuels been used. This fact affords a unique opportunity for comparing the relative efficiency obtained with these several fuels under nearly identical conditions. FURNACES The present furnace refinery at Great Falls was placed in operation in April, 1916. The original installation consisted of two furnaces, each with hearths 36 by 14 ft. and provided with fire boxes 10 by 12 ft. for firing lump coal on grates. These furnaces had air-cooled sand bottoms and chrome-brick side walls both above and below the metal line. The roofs were of 12-in. silica brick. Each furnace was provided with a waste-heat boiler of approximately 400 boiler-hp. capacity. We soon found that chrome brick was very unsatisfactory as sidewall material because of its excessive spalling. At the first opportunity the furnaces were rebuilt, using magnesite brick below the metal line and silica brick from the metal line to the roof. At the same time the thickness of the side walls was increased, thus decreasing the width of the hearth to 13 ft. At about this time also, the thickness of the furnace roofs was increased from 12 to 15 in. No further changes occurred in furnace design until 1922, when the use of lump coal on grates was abandoned in favor of pulverized coal.

Jan 1, 1932

By E. A. Smith, E. R. Parker

METALLURGISTS and engineers have always been interested in the mechanism of high-speed deformation because metals are rapidly deformed in various applications and manufacturing processes. The deformation of metals by impact loads has recently engaged the attention of a number of investigators. Many of their results have not been disclosed but some of the published investigations1-8 have shown that the tensile strength, yield strength and elongation generally increase with increasing strain rate. The investigation reported herein is an attempt to determine the reason for this increase in strength and elongation. Single-crystal copper specimens were broken in tension at impact velocities up to 100 ft. per sec. The distribution of slip bands in the fractured crystals was found to depend upon the strain rate. In the bars broken at high speeds, the slip bands appear to be more numerous. This might account for the higher strength as well as the greater elongation. EXPERIMENTAL PROCEDURE Single crystals of copper (approximately 99.98 per cent) were made in graphite molds by the conventional method of lowering the mold out of the hot zone of a hydrogen furnace at a rate of one inch per hour. Solidification progressed from the bottom upward, forming a single crystal. The crystals were about 0.30 in. in diameter and 4 in. long. They were made into test bars by sliding threaded steel bushings over each end of a crystal and then flowing silver solder between the crystal and the bushing. The inside diameter of the bushings was slightly greater than the diameter of the crystals, to allow space for the silver solder. The bushings were placed so that the gauge length of the crystals was one inch. The assembly is shown in Fig. I, with two views of a fractured crystal. Annealed polycrystalline copper bars of similar shape were machined from solid stock. X-ray measurements were made on all single crystals to determine their orienta¬tions. The results are shown in Fig. 2, where the location of the axis of each specimen is indicated on a standard projection. The bars were broken in a commercial variable-velocity tension im¬pact machine, which has been described in detail elsewhere.7,8 The stress and strain were recorded by means of wire strain gauges and a special commercial oscillo-raph, also described in detail elsewhere.9,10 The equipment and method can be briefly described as follows. The impact machine consists of a motor-driven flywheel containing a two-pronged hammer. This hammer is held retracted in the flywheel

Jan 1, 1944

By B. C. Craft

Oil and gas development in Arkansas during the year 1933 has been marked by considerable wildcat drilling, considering the overproduction prevalent in the oil industry. Arkansas showed an increase in drilling operations during 1933. There were 45 completions from 10 counties resulting in 7 oil wells and 38 dry holes, compared with 37 completions resulting in 4 oil wells and 33 dry holes during 1932. Miller County continued to be the most active area, with 18 completions resulting in 3 oil wells and 15 dry holes. Extensive exploration around the Miller County field has more definitely established the producing limits. It has confirmed the belief that produc-

Jan 1, 1934

By Hans Lundberq

IINDUSTRY'S attention is now focused on the production of munitions thereby creating a demand for certain minerals which in prewar days were produced only in limited quantities. Now production of these minerals must he increased from the known deposits and new deposits must be found. Can geophysics help? "War minerals" such as tin, vanadium, tungsten, antimony, manganese, chromium, and cinnabar have no physical characteristics sufficiently different front the country rook to permit their direct location by ordinary geophysical methods. As already demonstrated in work on gold and oil, useful information may be obtained indirectly, however, outlining structural features or geological conditions favorable for the deposition of such ores or the accumulation of oil. Recently, more direct and truly qualitative methods have been brought into a useful and practical stage, and by the combined application of old and new methods a technique has been developed which, it is hoped, will be of importance in the search for these vital minerals.

Jan 1, 1941

By Eugene A. Thiers, William V. Morris

INTRODUCTION Direct reduction processes reduce the various commercial forms of iron oxide (pellets, concentrate, fines, etc.) to metallic iron at temperatures lower than that of molten iron. Thus, this technology includes practically, all iron reduction processes other than blast furnaces and electric pig iron furnaces (whose output in terms of world production is negligible). The product of these processes which is known as direct reduced iron (DRI), or sponge iron, is primarily used as a source of metallic iron in steel-making operations. Interest in DRI, which has been significant since the early 1960s, increased significantly in recent years with the rapid growth of DRI installed capacity throughout the world. The importance of the subject for the Circum-Pacific region stems directly from the influence that DRI has on iron ore consumption and on future steel development for this region. Although there is widespread agreement that electric furnaces will continue to increase their share of global steel output, and especially so in the countries of the Pacific Steel community, some doubts exist about future scrap supplies being adequate to support growth at past rates. The authors believe that such doubts are soundly based. As this paper points out, the total supply of all metallics used in electric furnaces may not be adequate to support the extrapolated rapid growth in electric furnace steel production. This paper seeks to provide perspective on the global and Circum-Pacific prospects for DRI in light of recent energy price developments and the current recession. In this regard, the demand for DRI within the context of recent evolutionary patterns in steel-making, the outlook of DRI supply in terms of prevailing production costs, and the prospects of new technology are discussed. THE DEMAND FOR DRI Although several reports published in the last 10 years predict high rates of growth in DRI, the subject remains a controversial one. Significant growth has indeed occurred, but not to the extent anticipated in the studies summarized in Table 1. The substantial difference between previous expectations and present reality can be ascribed primarily to: (1) lower growth in steel production than formerly anticipated; (2) numerous cancellations of DRI facilities that were previously announced; and (3) a fundamental and probably irreversible change in the economics of DRI production. Note that DRI capacity at the end of 1980 was about 16 million tonnes, a significantly lower figure than any of the projections above. In addition, DRI production was only about half of capacity, reflecting the abnormally low rates of capacity utilization in this industry. [ ] Before examining the current outlook in steel, it is pertinent to note that the market for DRI is usually different in the industrialized countries of the West from that in developing countries. In the former, the available infrastructure and industry's diversification extends DRI's potential markets to numerous steelmaking, foundry, and other industrial applications, although competition from scrap and other forms of metallic iron is constant. Scrap is generally available in these countries and, therefore, DRI competes with it in electric furnace steelmaking, basic oxygen steelmaking (as a coolant), cupola foundry operations, or as an additive in the metallic charge for open hearth and blast furnaces. On the other hand, DRI in developing countries is often allocated exclusively to domestic electric furnace steelmaking or, when capacity exceeds domestic captive requirements, to export. Notwithstanding quality considerations, DRI is being and is likely to continue to be used predominantly as a source of metallics in iron and steel-making. Other uses of DRI, such as in copper cementation represent a marginal market in terms of overall tonnage and can be ignored at this point. Therefore, DRI demand is-determined by the overall availability of metallic scrap in its various forms--a function of steel production and its probable evolution. The Global Steel Outlook Given the present recession, an objective appraisal of the long-term outlook for steel is particularly difficult. On the one hand, historical trends and, especially, the inertial forces associated with such a basic industry as steel must be recognized; such trends suggest that the current stagnation with

Jan 1, 1982

By C. H. Stein

The Pennsylvania Legislature, on March 13, 1837, passed an act authorizing the Lehigh Coal & Navigation Co. to construct a railway to connect the North Branch Division of the Pennsylvania Canal with the slack water navigation of the Lehigh River; the navigation company accepted this act on May 10, 1837. Edwin A. Douglas, chief engineer for the navigation company, located the route for this railway from White Haven to Wilkes-Barre, which was called the Lehigh & Susquehanna Railroad. The object was to transport coal from the Wyoming Valley, of Pennsylvania, to the Atlantic seaboard. This railway was considered a marvelous piece of engineering, as it included a tunnel nearly 55 mi. long, and a series of inclines, or planes, up which the cars laden with coal were raised from the vicinity of Ashley to the summit of the mountain near Solomon's Gap, whence they were taken to White Haven by rail. There the coal was transferred to canal boats. In June, 1862, floods almost completely destroyed the upper division of the canal, so on March 4, 1863, the Pennsylvania Legislature passed an act prohibiting its restoration, but granted a charter for the construction of a railway from White Haven to Mauch Chunk to connect with the line from White Haven to Wilkes-Barre, previously built. On March 16, 1864, a supplementary act was passed extending the Lehigh & Susquehanna Railroad to Easton, Pa. This completed a direct all-rail route from Wilkes-Barre to the New York harbor (by way of the Central Railroad of New Jersey). Up to this time, all freight and passenger traffic passed over the planes, but in 1866 and 1867 there was constructed what was known as the "back track" down the mountain side between Solomon's Gap and Ashley over which all the passenger traffic and empty cars thereafter passed; it is now known as part of the main line. For the handling of the heavy coal traffic, however, this would have involved a continuous climb from Ashley, 170.27 mi., from New York, to Solomon's Gap, 157.8 mi. from New York, or a distance of 12.47 mi., and a total ascent of 1013.75 ft., composed of grades 95.61, 83, and 51.4 ft. per mi., respectively, and

Jan 1, 1922

By George B. Lee

During the two years in which the new reduction-works of the Copper Queen Consolidated Mining Co. have been in operation at Douglas, Ariz., there has developed a remarkable condition in regard to the corrosive action of the water used to cool the jackets of the blast-furnaces. Were it not for the many contradictory features, it might pass as one of the unavoidable troubles due to the composition of the water. This water, obtained from wells 600 ft. deep, is also used in the steam-boilers, and its composition, as shown by the following analysis, does not indicate the presence of any ingredient which would explain the corrosion: Grains Per U. S. Gal. Silica,...........0.861 Iron oxide and alumina,....... 0.223 Calcium carbonate,....... 0.261 Calcium sulphate,................. Magnesium carbonate,........... Sodium and potassium sulphates,..14.850 Sodium and potassium chlorides,.9.732 Sodium and potassium carbonate, . 6.482 32.409 The jackets are made of inner plates 0.5 in. thick and an outer plate # in. thick, with 3/8-in. stiffeners between the inner and outer plates. In from 10 to 12 months the inner plates have been reduced by corrosion to a thickness of from + to & in., while the outer plate in the same time is reduced by less than 1/16 in., and the stiffeners show very little corrosion. The plates are pitted and eaten away in some places more than in others. There is practically no scale found on the jackets, but when cleaned considerable iron oxide is found in the bottoms. With an action so marked, serious trouble would be expected in the boilers, but, on the contrary, a recent inspection by a

Jan 1, 1908

By Samuel L. Hoyt

THE present report represents that part of the work that has been done by the War Minerals Investigation, Manganese Section, of the Bureau of Mines, on the use of manganese alloys in open-hearth practice. The magnitude of the work and the number of people participating in one way or another make it difficult to acknowledge adequately the services of all who have contributed to the success of the work. It would, be amiss, however, to pass to the body of the report without mentioning the hearty coöperation and willingness to assist of the various manufacturing interests. With such a sympathetic attitude toward this investigation, our work was assured of success. Inasmuch as the unhappy circumstances that rendered this investigation necessary have now passed, this report is made in 'the hope that the results may prove of some permanent value to the peace-tine operation of our open-hearth industry. Broadly speaking, the purpose of the manganese investigation was to consider the most suitable means of utilizing our domestic supply of manganese and thus relieve, to the maximum extent possible, our shipping of the burden of importing manganese ores. It was not held that any decided shortage of manganese 'was imminent but rather that every legitimate means should be utilized for making our ship tonnage available to European service. While we have considerable metallic manganese in this country, it occurs largely as a low-grade mixture with iron or silica or with both. The open-hearth investigations, therefore, were carried on to determine the extent to which domestic or low-grade alloys could properly be substituted for high-grade alloys without materially impairing the steel production as to either quality or quantity. Also, it was held that such an investigation would yield valuable results to the steel industry as well as contribute, in no small way, toward

Jan 2, 1919

By S. C. Carapella, E. A. Peretti

DURING a literature survey of the indium-zinc phase diagram, controversial reports on the composition of the eutectic point were encountered. The value reported in the investigation of Wilson and Perettil and in a later investigation by Valen-tiner' was 4.0 wt pct zinc. The most recent work recorded on this system consisted of an exhaustive survey of alloys by Rhines and Grobe8 in which they indicate a value of 2.8 wt pct zinc for the eutectic composition. To clarify this aspect of the diagram, a series of alloys were prepared by melting the respective constituents in a glass test tube under a covering of mineral oil and slowly cooling the melt in a furnace. The zinc used was Baker's C.P. and had the following analysis: insoluble in H2SO4—0.0l pct; pb—0.001 pct; Fe-—0.001 pct. The indium, which was supplied by the Indium Corporation of America, had a purity of 99.9'7 pet with the following impurities: Cu—0.002 pct; Pb—0.006 pct; Sn—0.01 pct; Zn—0.01 pct. The alloys were prepared for metal-lographic examination using a technique already reported' and a new value of 2.0 ± 0.1 wt pct zinc was observed. An alloy containing 2.00 wt pct zinc was also made by melting the constituents under a vacuum. In both of these methods of alloy preparation the losses can be kept extremely small. Again, the characteristic eutectic structure was obtained, assuring confidence in this value. The accompanying micrographs are presented in support of this point. Fig. la represents an alloy containing 4.00 wt pet zinc, and reveals excess zinc particles, which precludes the value of both Wilson and Peretti, and Valentiner. Fig. lb, gives the structure of an alloy containing 2.2 wt pct zinc, also showing the presence of excess zinc. Fig. lc is a micrograph of a typical structure of the eutectic observed in several sections of the 2.0 wt pct alloy. In the 1.8 pet zinc alloy, fig. id, the definite presence of the primary indium can be noted. From these re-

Jan 1, 1951

By F. N. Rhines

Despite the large amount of study which has been devoted to the subject our present knowledge of the copper-oxygen system remains incomplete and unsatisfactory .in many respects. This applies particularly to those regions in which solid metallic copper exists. The primary object of the present paper is the contribution of new information relative to the solid solubility of oxygen (or cuprous oxide) in copper at atmospheric pressure, together with certain observations in the low-pressure regions of the system. It seems appropriate also to present a brief summary of the outstanding previous work on the constitution of mixtures of copper with its lowest oxide in order. to show the relation between the new facts and the system as a whole. The earliest recorded investigations of the copper-oxygen system are those of M. S. Lucas(l) $ and of M. Chevillot(2) in 1819 and 1820. Lucas believed that liquid copper is capable of dissolving its oxide, but neither he nor Chevillot was able to furnish convincing proof of this property. It was not until 1866 that T. Graham(3) definitely established the existence of such a solubility. Nine years later W. Hampe(4) measured its extent and roughly outlined the copper-rich portion of the system. The first really precise examination of the constitutional relationship between copper and cuprous oxide, however, was that of E. Heyn(5) who in 1900 published a temperature-concentration diagram covering the range from 0 to 10 per cent of cuprous oxide at atmospheric pressure. Within these limits of composition cuprous oxide was found to dissolve in liquid copper, forming at 3.4 to 3.5 per cent a eutectic which melted at 1065" C. R. E. Slade and F. D. Farrow(6) extended these studies to mixtures of higher oxygen content. They discovered that between 20 and 95 per cent of cuprous oxide the metal and oxide form two liquid phases at a monotectic reaction of 1195" C. The span of the biliquidal region diminishes slightly

Jan 1, 1934

By G. Sachs, E. J. Riping

All ferrous alloys can be made brittle by straining at sufficiently low temperatures. However, the changes in mechanical properties for different ferrous materials with decreasing testing temperature do not appear to follow any universal law. In particular, complex effects of testing temperature have been observed if cold worked steels were subjected to tensile tests at low temperatures. EFFECTS OF PRESTRAINING AT A TEMPERATURE ABOVE THE TESTING TEMPERATURE ON THE FRACTURE CHARACTERISTICS‡ A considerable amount of data has been presented by a number of investigators on the fracture characteristics of various cold worked steels.' These data usually relate to a two-step procedure first used by Davidenkov,² consisting of stretching by tension to a certain strain or " prestraining" at room temperature and then completing the tensile test, or "testing" at the temperature of liquid air. On the basis of data of this type made available to date, ferrous alloys can be classified into two groups with respect to their fracture characteristics observed on testing at a low temperature after prestraining at room temperature. Very complex phenomena have been observed for all annealed steels. On the other hand, some observations indicate that steels in certain other conditions represent a fundamentally simpler relation. In considering the effect of prestraining at one temperature on the properties obtained at some lower temperature, it should be expected that any cold work reduces the ductility retained in proportion to the magnitude of the cold work. However, the test data presented to date indicate that only heat treated (quenched and tempered) steels appear to conform to this expectation, according to the very limited test data in Fig 1, presented by McAdam, Geil and Mebs. This series of tests, Fig 1, shows that the retained ductility became smaller the larger the prestrain. However, this decrease is less than the amount of prestrain or, in other words, less than the decrease in ductility at the prestraining temperature. These effects of prestraining are fundamentally identical with those observed by Bridgman3 when a steel was prestrained (in tension) under hydrostatic pressure and then subjected to a regular tension test. It appears, therefore, that the basic effect of prestraining under conditions which yield a higher ductility than the (subsequent) testing procedure, consists of gradually increasing the total ductility of the metal from the initial low value of testing to the higher value of prestraining. On the other hand, all annealed steels, if cold worked by tension at room temperature and then tested at a lower temperature, provided that some ductility is retained, showed a far more complex behavior than that discussed above. This relationship is exemplified by Fig 2, for three pearlitic steels.4,5 These particular steels were selected because of the various shapes of their ductility-prestrain curves. All three steels, and any other investigated so far, suffered a rapid decrease in retained (and consequently also in total) ductility when subjected to small pre-strains. Then, after exceeding a certain prestrain it was generally observed that the ductility recovered.* This rather complex behavior of annealed steels may be tentatively correlated with the presence of stretcher strains at small restrains. Heat treated steels do not exhibit stretcher strains. This fact might possibly explain their simpler prestrain-retained ductility relationship. The destructive effect of these stretcher strains may possibly be associated with the presence of triaxiality, which may occur in any highly non-uniform stress and strain state (and which is retained as residual stress after unloading). Even a small degree of triaxiality may then cause a reduction in ductility, or even embrittlement at a sufficiently low testing temperature. The discussion presented above deals with the effects of cold working at a high temperature on the fracturing

Jan 1, 1950

By E. DeGolyer

THE petroleum production of the world for 1924 again passed the billion-barrel mark, as it did in 1923. A preliminary estimate of production is 1,016,000,000 bbl., a decrease of 1,100,000 bbl., or less than 1 per cent. from the 1,017,100,000 bbl. produced in 1923, the year of greatest production. FIG. 1.-TOTAL WORLD AND UNITED STATES PRODUCTION. Production in the United States decreased 18,500,000 bbl., the. first decrease in yearly production since 1906. Mexican production decreased almost 10,000,000 bbl. Russia, Persia, Roumania, Venezuela, and Peru increased their production by an amount almost great enough to offset the decline in the United States and Mexico. The decline in the production in the United States and Mexico was considerably less than anticipated by leading geologists, economists, and statisticians; nor did the increase in consumption entirely meet the expectations of estimators. Early in the year, the statistical department of one of the most important oil companies forecast a draft on stocks, from an excess of demand over supply, of about 80,000,000 bbl. Instead of decreasing our stocks, they were increased by about 33,000,000 barrels.

Jan 3, 1925

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

The thermodynamic properties of- liquid Mg-Pb allojs have been determined by an isopiestic method from 18 to 42 at. pct Pb and by a thevmodynumic analysis of the phase diagram frofiz 0 to 100 at. pct Pb. In the overlapping composition range the magneszupn activity values derived by the two methods are in excellent agreement, thus mutually supporting the correctness of the Mg-Pb phase diagram previously determined by the authors and of the acticitzes deriz~ed isopiestically. SEVERAL studies have been made of the thermody-namic properties of liquid Mg-Pb alloys. Wagner and Engelhardt,1 Lantratov,2 Knappwost,3 Sryvalin et al.* and Wilson5 used the electromotive-force method, Scheil and Wolf8 and Schmahl and Sieben" applied the transpiration technique, and the present authors8 utilized the phase diagram to determine the activity of magnesium in the Mg-Pb system. The results of these studies are not in very good agreement and could not be incorporated into a general systematic analysis of the thermodynamic properties of the homologous series of the Mg-Group IV B systems Mg-Pb,8 Mg-Sn,° Mg-Ge,10and Mg-Si.11 The thermodynamic properties of the Mg-Pb system were therefore re investigated by an isopiestic technique which has been developed for similar studies in the Mg-SnB and Mg-Ge10 systems- Lead specimens, contained in iron or graphite crucibles, were heated in a temperature gradient in an evacuated and sealed titanium reaction tube and equilibrated with magnesium vapor of known vapor pressure to form alloys of compositions which depended on their temperatures, the temperature of the magnesium vapor source, and the thermodynamic properties of the system. EXPERIMENTAL PROCEDURE Magnesium (Dominion Magnesium Ltd., Toronto, Canada) of 99.99+ pct purity and lead (American Smelting and Refining Co.) of 99.999 pct purity were used. In the early experiments, Runs 2 and 3, the alloys were contained in uncovered high-purity iron crucibles. Alloys formed in the uncovered iron crucibles had to be chemically analyzed owing to the slight volatility of lead under the imposed experimental equilibration conditions. The compositions of these alloys were determined by a gravimetric analysis of lead as lead chromate. To avoid this problem, the remaining runs were made in covered graphite crucibles 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- i reactivity of graphite with lead and magnesium has been previously established,' and the experimental procedure has been described in full detail.' In the runs using covered graphite crucibles it was found that the weight increases of the crucibles and their contents after equilibration equaled the magnesium contents of the alloys within the accuracy of the chemical analysis (i0.3 at. pct Pb). Clearly, the small lid openings of the graphite crucibles prevented significant lead losses during a run, and the weight increase was therefore taken as the magnesium content of the alloys. EXPERIMENTAL RESULTS At thermodynamic equilibrium the magnesium partial pressure of the specimens equaled that of the reservoir. Since the magnesium reservoir was always maintained at the temperature minimum of the system, the activity of magnesium of any specimen was given by the ratio of the magnesium reservoir pressure to the vapor pressure of pure magnesium at the specimen temperature. The standard state was chosen as liquid magnesium and the vapor pressure of liquid magnesium

Jan 1, 1968

By C. Willard Hayes

The determination of the question whether the Mayari and Moa mining-claims of the Spanish-American Iron Co. have been rightly denounced under the third section of the law of bases rests on the findings in the following questions of fact: 1. Is the mineral an iron-ore ? 2. Is the iron-ore a bog iron-ore ? 3. Is the iron-ore ocher ? 4. If ocher is present, can it be mined separately and independently of the iron-ore ? 1. Is the Mineral an Iron-Orb? Since the material is shown by a large number of analyses to contain from 41 to 50 per cent. of metallic iron and less than

Jan 1, 1912

By W. T. Hicks

Visual observation of the oxidation of columbium shows that the protective behavior noted previously in gravimetric work in the early stages of the reaction below 600°C and throughout the reaction at 640°C is associated with an adherent oxide. The fact that the oxide is seen to move outward from the metal at temperatures from 550° to 935°C implies that the reaction takes place at the oxide-metal interface throughout this temperature range. THE work described in this paper further clarifies the complex oxidation kinetics of Cb revealed, for example, by the continuous gravimetric studies of T. L. Kolski.1 Time-lapse motion picture studies reveal details of the reaction not provided by a study of the combustion products. EXPERIMENTAL PROCEDURE Cb specimens were prepared from material with the following typical analysis: 0, 0.03 pct; N, 0.002 pct; C, 0.006 pct; Ta, 0.04 pct; Fe, 0.01 pct; Ni <0.003 pct; and Cr <0.003 pct. Arc-cast ingots were swaged and cold rolled into slabs. These slabs were machined into blocks 7/16 by 7/16 by 7/16 in; 1/16-in. holes were drilled through the large face of the blocks for suspension. The samples were then de-greased and annealed 1 hr at 1200°C in vacuum. The sample was suspended by a platinum and Pt 10 pct Rh thermocouple inside a 1-in. quartz tube in a Kanthal wound furnace (2 in. OD by 4 in. long) equipped with windows 1/2 in. sq. A Cine-Kodak Special II 16 mm motion picture camera was trained on the sample through a Spencer microscope adjusted so that a magnification of X1.5 resulted on the film. Super Anscochrome film was used to record the events in color. Argon was flushed through the furnace while the sample came to temperature. The argon was then replaced by a stream of dry oxygen at 1 atm. Pictures were taken at the rate of eight per second for about 20 sec during the change of atmosphere. Then by use of a Stevens time-lapse device pictures were taken at the rate of four per minute starting within 1 min of the initial oxygen flow. In this manner continuous visual records of the oxidation of pure Cb

Jan 1, 1962

By J. R. Cahoon, W. V. Youdelis

In a previous communication by one of us,1 a theory of inverse segregation was presented by which the maximum segregation and segregation distribution throughout a unidirectionally solidified, binary-alloy ingot could be calculated. The theory, which is based on the mechanism of volume contraction and interdendritic flow, quantitatively accounts for the observed maximum segregation in the A1 (rich)-CU&apos; and Al-Zn2 alloy systems, and for the segregation distribution along the ingot lengths for the A1-Cu system.&apos;&apos;4 One of the drawbacks to a more extensive use of the segregation equations is their complexity, particularly for the calculation of the segregation distribution throughout the length of the ingot, involving long tedious numerical calculations to obtain the segregation. Computer pro- grams, written in Fortran II for use on an IBM 1620 computer, have been developed by the authors (and are available from them), providing quick and accurate methods for the determination of the theoretical maximum segregation in any binary-alloy system, and also for the segregation distribution in any unidirectionally solidified binary-alloy ingot. The segregation distribution is controlled by the lengths of the various solidification zones&apos;74 which are in turn controlled by the cooling rate, and are determined from temperature-distribution curves obtained during solidification. The theoretical segregation distributions shown in Fig. 1 illustrate the effect of the zone lengths on the distribution Curve 1, indicative of a slowly cooled ingot, represents an ingot having long solidification zones, while Curve 2, indicative of a rapidly cooled ingot, represents an ingot having relatively short zones. Although these distributions are calculated for an A1-10 pct Cu ingot, the shape of the distribution would be similar for any binary-alloy ingot. These curves show clearly why early workers obtained results which indicated that the maximum (chill-face) segregation approached zero at very fast cooling rates.3 Actually, the maximum segregation is independent of cooling rate,&apos; but even at short distances from the chill face the amount of segregation drops considerably, particularly in a rapidly cooled ingot, making it very difficult to establish the amount of segregation occurring at the chill-face. The authors would like to thank Dr. J. A. Goldak for his assistance in the preparation of the programs. The financial assistance of the Steel Co. of Canada and of the National Research Council of Canada in the form of Scholarships to one of us (J. R. Cahoon) is gratefully acknowledged.

Jan 1, 1964

By Donald R. Williamson

Ore estimation at Cyprus Pima mine begins with estimating average copper grades for mine model blocks. Accuracy of the estimates has been checked four times in the last several years by comparing the estimates with arithmetic averages of corresponding blasthole (BH) assays. The data file now contains 3.567 estimated blockgrades and more than 10,000 blasthole assays. These data were compared by straight-line regression analysis at appropriate intervals as the body of data grew. Arithmetic averages of the estimates differed each time from arithmetic averages of the BH averages by nearly the same amount. More significantly, regression curves of the new total sets of data did not change position appreciably showing that copper grade estimates of blocks in all grade ranges from the lowest to the highest grade ores remained in error by nearly the same amount. Other studies revealed that core hole assays of the dominant ore type are biased and that that bias almost equals the error in estimation. Discovery of constancy in error indicated that regression analysis could be a means for correcting estimates of average block copper grades. A correction for estimated block grades was developed. It required determining which regression is appropriate for the particular problem, and a mechanism that is demonstrably sound. This paper describes the problem and the solution: No comparable study has been, found in the literature. Two other applications of regression analysis to metal grade comparisons are presented. Each adds a bit of support to a generalization which was suggested by correction of average block copper grades, namely, when performance of an estimate is to be evaluated, the variable taken to be the yardstick for the performance should be regressed on the estimate.

Jan 1, 1980

[Trans. No,PlaceDate Vol. Page1 1. Wilkes-Barre, Pa*May, &apos;71 13 2, Bethlehem, Pa Aug., &apos;71110 3, Troy, N. Y Nov., &apos;71.. 113 4. Philadelphia, PaFeb,, &apos;72.. 117 5, New York, N, Y.*May, &apos;72,, 120 6. Pittsburgh, Pa Oct,, &apos;72,, 125 7. Boston, Mass Feb,, &apos;73.. 128 8. Philadelphia, Pa,*May, &apos;73., 23 9. Easton, PaOct., &apos;73., 27 10. New York, N, Y Feb., &apos;74,, 211 11. St. Louis, Mo,*May, &apos;74.. 33 12, Hazleton, PaOct., &apos;74., 38 13, New Haven, ConnFeb., &apos;75., 315 14. Dover, N. J,*May, &apos;75.. 43 15, Cleveland, 0Oct,, &apos;75,, 49]

Jan 1, 1928