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By N. Standish

Heat transfer coefficients have been measured in beds of various packings irrigated with mercury and molten fusible alloy countercurrent to hot gases. The measured coefficients for both systems were found to increase with gas velocities and liquid rates. Correlations were determined which show this dependence and also indicate that heat transfer in these systems is influenced by the liquid flow characteristics and the thermal conductivity of the gas and the solid packings. A heat transfer model has beer2 proposed which explains the various features of the experimental results. On the basis of this study, which gives an insight into the heat exchange in the melting zone of the blast furnace, it was concluded that by comparison with the furnace stack heat transfer coefficients are about 1.5 times higher in the melting zone. EACH year large tonnages of metal are produced in operations which, in part, involve liquid metal irrigation of "packings" countercurrent to hot gases. The melting zone in blast furnaces and in cupolas is a good example of packings irrigated with a liquid melt countercurrent to gases. In all instances of this kind large amounts of heat are exchanged and it is desirable to have some knowledge of heat transfer phenomena involved in these systems. So far the most common method of analyzing furnace efficiencies, fuel requirements, and the general thermal state of the furnace has been through the use of heat balances. As heat balances are essentially statements of the first law of thermodynamics they give no real indication of the factors which govern heat transfer between phases in the various zones of blast furnaces. Hence, rational improvement in production efficiency and the development of theoretical models is only possible if the heat transfer characteristics are known at every stage of the process and related to the important variables involved. This has been generally recognized for some time but it was only recently that Kitaev et al.' have produced a comprehensive treatment of heat transfer in solid-gas countercurrent systems such as the blast furnace stack and the packed bed regenerator. Using their treatment it is now possible to predict the effect of particle size, thermal conductivity, bed porosity, and the flow rates of both the gas and the solid material on the heat transfer in the blast furnace stack. However, the stack of a blast furnace is only one part of an integral unit for which the heat transfer analysis cannot be complete without also considering the heat exchange in the melting zone. The complexity of heat transfer processes in this region of the furnace has so far escaped quantitative description. Yet, the melting zone accounts for a greater amount of heat exchange than all the other zones of the furnace put together. Moreover, if the reduction of oxides in the melting zone proceeds in part in the liquid state the importance of heat transfer on furnace productivity and on the metal and slag temperatures is obvious. THEORY Heat transfer for two-phase flow in packed beds is a complex problem involving a number of heat exchange paths for which interphase areas are not known with any degree of certainty. Analytical solution is, therefore, difficult. This difficulty is emphasized by noting that Rabinovich~ and Luck have only recently solved the steady-state heat transfer for simplified two-phase heat exchangers of known area. However, useful progress can be made for the system considered by making a not unreasonable assumption that the usual heat transfer considerations apply and restricting treatment to the steady state. For these conditions the rate of heat transfer dq in a height dz of a packed bed of unit area is: dq = UaATdz [I.] Integration of Eq. [I] then gives the total heat transferred: assuming both U, the overall heat transfer coefficient, and a, the interphase area, to be independent of bed height. Since a, in these systems, is unknown it is convenient to combine this term with U. The group U, then represents the overall heat transfer coefficient on a volumetric basis. If AT is linear with q, then for a bed of unit volume Eq. [Z] can be integrated to give: is the log mean of terminal temperature differences. From Eq. [3] U, can be readily calculated as q and {AT)im are experimentally obtained quantities, but a difficulty arises in interpreting its meaning. Two approaches are possible depending on whether the effect of packing in the transfer of heat is neglected or not. If the packing is thermally decoupled then the resistance concept gives the relationship: which states that the overall resistance is the sum of the gas phase and the liquid phase resistances (assuming areas are equal throughout). Because the resistance to heat transfer in liquid metals is negligible by comparison with that of the gas,4 Eq. [4] can be simplified, i.e.:

Jan 1, 1969

By J. J. Fritts, J. L. Patrick, T. L. Wright, C. O. Ensign, W. S. White, J. W. Trammell, J. C. Wright, D. J. Hathaway, R. J. Leone

The copper deposit at White Pine, Michigan, from which a little more than 5 per cent of United States primary copper currently is produced, is a large stratiform orebody, 4 to 25 feet thick and several miles across. The present ore column, containing about 1.2 per cent copper as chalcocite and native copper, is confined to the basal beds of the Nonesuch Shale. This upper Keweenawan (Upper Precambrian) formation is a distinctive gray siltstone unit, about 600 feet thick, overlying and overlain by thick red-bed sequences. All these rocks contain abundant volcanic debris, but the latest known igneous activity within 50 miles antedated the Nonesuch Shale. The rocks are unmetamorphosed and only moderately deformed, mainly by tilting and faults. Pyrite, presumably syngenetic, is the only prominent sulfide throughout most of the Nonesuch Shale. The basal beds of the formation, however, contain disseminated copper minerals instead of pyrite and constitute the cupriferous zone. On a regional scale, the top of the cupriferous zone cuts across bedding, and ranges from an inch or so above the base of the formation in some areas to more than 50 feet in others. However, within the cupriferous zone the distribution of copper shows remarkable stratigraphic control. Certain beds are copper-rich compared to the beds that lie between them and the differences persist throughout the White Pine region. Several darkgray thinly laminated beds in the lower 10 to 25 feet of the Nonesuch Shale are rich enough and sufficiently close enough together to constitute a mineable thickness where they lie within the cupriferous zone. Pyrite is the characteristic sulfide of the Nonesuch Shale as a whole. The principal sulfide mineral of the cupriferous zone at the base of the formation is chalcocite. The succession of minerals outward and upward from the center of the cupriferous zone is native copper-chalcocite-bornite-chalcopyrite- pyrite. The bornite and chalcopyrite are confined to a narrow fringe at the margin of the cupriferous zone. This pattern of mineral zones is believed to represent reaction between syngenetic pyrite and introduced copper. The main copper mineralization is independent of structure and apparently antedates deformation. Details of the geometry of the cupriferous zone indicate the possibility that copper was introduced from the underlying sandstone prior to lithification. The source of the mineralizing solutions and their copper is not known.

Jan 1, 1968

By George C. Heikes

ALTHOUGH the application of light metals in war materiel increased during the year, based on the number of uses, the trend in aluminum and magnesium production in 1944 was characterized by a sharp decline in the production of both metals accompanied by a further accumulation of large Government reserve stocks. Several primary reduction plants were curtailed to prevent building excessive inventories. By the end of the year, however, a lively revival of war production took place when resistance stiffened on the western front in Europe. Production of primary aluminum ingot was reduced from over 90,000 tons per month at the start of the year to 45.000 tons per month by the end of the year.

Jan 1, 1945

By F. H. Wilson, R. M. Brick

With the papers of Palmer and Smith1 and of Burghoff and Bohlen,2 published in 1942, understanding of the problem of the development of ears on deep-drawn brass cups was brought to the point where, from a practical standpoint, producers of brass sheet could keep earing under control. However, these very practical results raised questions concerning the reasons for the observed behavior. Since plastic deformation is fundamentally a function of crystallographic slip, these reasons must be considered in the light of the textures to be found in the annealed sheet. Various attempts have been made. to interpret the mechanism of ear formation by correlation with the preferred orientation and the anisotropy of the sheet. However, none of these has satisfactorily explained why ears are usually found in the rolling and transverse directions for copper but at 45' to these directions for brass. This paper offers additional data on these two related subjects and has been divided into two sections The first section provides a survey of the recrystallization textures of brass as affected by annealing temperatures and prior reductions, and an account of the caring behavior which accompanies these textures. The second section reports new data on the anisotropy that accompanies a characteristic texture for brass and endeavors with partial success to establish the factors that account for the difference in earing behavior between copper and brass Earing BehavioR oF Brass Review of Textures The recrystallization texture of severely rolled brass was first reported by Bass and Glocker.3 The preferred orientation to which this texture, obtained from metal annealed at 500°C., was most akin was (II3)[I12] This texture has been confirmed by Bauer, von Göler and Sachs;4 Brick;' Brick, Martin and Angier;6 and Cook and Richards7 who, in general, used annealing temperatures under 500°C. Bass and Glocker3 also reported the recrystallization texture at 850°C. to be the same as at 500°C. They analyzed their textures by means of single photograms obtained with white radiation. The photo-grams for both temperatures are reproduced in their paper, and there is a strong similarity between the two. However, for the latter temperature, the number of spots registered on the film was remarkably large for the grain size to be expected, and the authors made no mention of using a technique that would integrate a large enough area of the specimen to produce so many spots. The only other attempt to determine textures resulting from high temperature

Jan 1, 1945

By Edward C. Stephens, Robert R. Coats

High-grade copper ore was discovered in 1932 in the long-dormant Mountain City (Cope) mining district, Elko County, Nevada. From 1932 to 1947, the one producing mine in the district, the Mountain City Copper Mine, produced 1,109,878 short dry tons of ore averaging 9.745 per cent copper, 0.274 ounces of silver, and 0.0057 ounces of gold per ton. The Mountain City Copper Mine is developed in eugeosynclinal rocks of Ordovician age, the Valmy Formation, which is part of the upper plate of the Roberts Mountains thrust. On the Valmy were deposited unconformably first, a elastic formation of Devonian or Mississippian age, the Grossman Formation, succeeded unconformably by a ·sequence of three conformable formations, the Banner, the Nelson, and the Mountain City. The Banner Formation probably is early Late Mississippian in age; the ages of the Nelson and Mountain City are not known precisely but are believed to be of Late Mississippian and Carboniferous(?) age, respectively. A thick formation of elastic rocks, limestone, and volcanics, the Reservation Hill Formation, has been thrust over the Mountain City. The age of the Reservation Hill is unknown but is presumed to be Pennsylvanian(?) and Permian(?). Several plutons of Cretaceous quartz monzonite intrude the Paleozoic formations; they and the intruded formations have been laid bare by erosion, and several sequences of volcanic rocks of Miocene and Pliocene age, and perhaps in part older, have been successively deposited on irregular erosion surfaces. The primary mineralization of the Mountain City Copper Mine is believed to postdate the deposition of the Nelson Formation and to predate the intrusion of the quartz monzonite. The primary ore bodies are lenticular in shape and are composed largely of quartz, pyrite, and chalcopyrite. The ore lenses, in general, strike northwestward and dip northward. They occur in the Valmy Formation within a definite stratigraphic sequence composed largely of shales with associated minor quartzite lenses. The ore is epigenetic. The principal ore body, the "200," was completely leached to the 200 level. Abruptly beneath the barren gossan was supergene copper sulfide ore, much of which assayed 50 per cent copper. The secondary copper minerals are sooty and massive chalcocite, bornite, and covellite. The supergene enrichment of the ore may have required a large part of Tertiary time.

Jan 1, 1968

By J. R. Stone, G. D. Storm

Design features and operating methods of ASARCO's new unit for the continuous melting and casting of tough pitch copper at Perth Amboy are described. Preliminary studies made for determinitzg economic feasibility and design details are also presented. Cathodes are preheated with oil and melted in an electric furnace at 40-ton per hr rate, from whence the molten copper is fed simultaneously to the wire bar casting wheel and the continuous casting of cakes and billets. In the early 1950's the copper refining furnaces at ASARCO's Perth Amboy plant reached a point where major expenditures would have to be made for replacement of the furnaces and the auxiliary equipment. The problem was whether to continue with the standard reverberatory furnaces or to consider continuous melting in electric furnaces. Reverberatory furnaces have been used for years in the copper industry and for some 50 years at the Perth Amboy plant. Reverberatory melting practice, however, imposes certain restrictions. First, labor costs are high, usually requiring three shifts per day. Secondly, they operate on a batch basis, the conventional operation being a 24-hr cycle including

Jan 1, 1961

By Charles Will Wright

MINERAL production in almost all European countries suffered a sharp setback because of the war. Plants were damaged, transportation facilities disrupted, and labor dispersed and demoralized. Since the war, due to lack of confidence and economic stability, there has been little incentive to rebuild and expand the mineral industries even though a big demand at high prices exists for mineral products. Most mining and metallurgical companies in Europe hesitate to invest their capital because of the tendency towards nationalizing industry, high taxes, and low output of labor, as well as the deficiency of mine supplies and equipment within their countries. In short, they do not have faith in the future, and for these same reasons and fears most of the mining companies in America will not risk capital investment in Europe. In Europe, including the United Kingdom, free enterprise has been losing ground and as a result the foundation of their economic welfare is being undermined. American mining interests willing to take the initiative could help in counteracting this influence if a way were found for them to co-operate with the European producer without too great a risk.

Jan 1, 1948

CONTENTS PAGE BARTON, D. C.-The Eötvös Torsion Balance Method of mapping Geologic Structure (T. P. No. 50) 1 GEORGE, P. W.-Experiments with Eötvös Torsion Balance in the Tri-State Zinc and Lead District (T. P. No. 65). 15 LANCASTER-JONES, E.-The Computation of Eötvös Gravity Effects (T. P. No.75) HEILAND, C. A.-A Cartographic Correction for the Eötvös Torsion Balance-(T. P. No. 52) 17 SLICHTER; L. B.-Certain Aspects of Magnetic Surveying (T. P. No. 120). . . . 18 WEAVER, W.-Certain Applications of the Surface Potential Method (T. P. No.121) LUNDBERG, H.-Recent Results in Electrical Prospecting for Ore (T. P. No. 98). . 20 HOTCHKISS, W. 0., ROONEY, W. J. and FISHER, J.-Earth-resistivity Measure-ments in the Lake Superior Copper Country (T. P. No. 82) 21 LEONARDON, E. G. and KELLY, S. F.-Some Applications of Potential Methods to Structural Studies (T. P. No. 115) 23 MASON, M.-Geophysical Exploration for Ores (T. P. No. 45) 25 The Eötvös. Torsion Balance Method of Mapping Geologic Structure Discussion of the paper of D. C.. Barton, issued as Technical Publication No. 50 with Mining and, Metallurgy, February, 1928. D. C. BARTON.-The field surveys which I have been privileged to use as illustrations for this paper were done for Mr. DeGolyer's companies and were released through his favor. W. J. MILLARD, Tulsa, Okla.-Has any oil been found by the torsion balance in West Texas? D. C. BARTON.-NO new oilfield has been discovered on the basis of torsion balance work. It has had some part in controlling the policy of certain companies in playing the extension of known oil fields. A number of "T. B." structures have been drilled and dry holes obtained. Of those known to the writer, one apparently was a structural high, one is a broad general high but locally low and probably is a deep-seated structural high, one seems normal although the control is poor, and one was considered structurally low but is now suspected by some geologists of being structurally high. E. L. DEGOLYER, New York, N. Y.-A large gravity structure, generally referred to, I believe, as the Crosby County Structure, has been found in West Texas. This structure is perfectly symmetrical with the arrows all pointing toward a common center, very much like the Nash salt-dome pattern in Dr. Barton's paper (Fig. 9). One of the peculiar things about it, from the standpoint of the gravity high, is that it is so

Jan 1, 1928

Jan 1, 1881

By AIME AIME

WHEN Russell B. Paul was born in Russell Gulch, Gilpin County, Colorado, that district was the state's leading gold producer. The son of Dr. Henry Paul, who had gone to Colorado from Missouri during the golden era following the Civil War, and had joined the Institute in 1889 when he was manager of the famous Aspen mine, young Paul's early life was steeped in a mining atmosphere from which developed his selection of mining engineering as a profes¬sion. After receiving his E.M. degree from the Colorado School of Mines in 1902, Mr. Paul worked in Colorado and Honduras. Returning from Central America he was married to Mary Ellen Gilmour, daughter of a prominent Central City mining man;

Jan 1, 1943

By A. B. Kinzel

ALTHOUGH the iron-carbon diagram has undergone many changes in the last 20 years, the region below the eutectoid line and up to approxi-mately 1.7 per cent carbon has been little affected. This region is generally considered to consist of cementite and ferrite. Graphite has been noted occasionally in the hypereutectoid steel region, and the ready formation of graphite nodules in malleable cast iron is a phenomenon difficult to interpret in the light of cementite, supposedly stable at sub-eutectoid temperatures. In this case the graphite formation has been partly explained by the presence of silicon, and many have believed that silicon acts to change the stable state rather than to accelerate reactions so as to arrive at the stable state in a briefer period of time. Consider-ation of this phenomenon indicates that cementite is not the stable phase in the temperature composition zone referred to. In the course of examining a low-carbon steel tube taken from a petroleum cracking still, which had been in service for approximately three years at temperatures somewhat below the eutectoid temperature, observations were made that shed light on this entire subject. The tube in question analyzed:1 C, 0.15 per cent; Mn, 0.49; Si, 0.02; S, 0.023; P, 0.015. The microstructure of the tube after service is shown in Figs. 1 and 2. From these it is evident that cementite as such is absent, and that in its place nodular graphite has been formed. In order to check this observation further, samples taken from the tube were heated at 850° C. for varying periods of time. The small samples were put into a large hot furnace, and the total time is recorded. The structure of the

Jan 1, 1934

By PALMER H. TYLER

WHEN the Mid-Continent Section of the A. I. M. E. met at the roof garden dining room of the Tulsa Club on Monday evening, May 13, most of the members present came prepared with a credulity-stretching yarn of some sort or other, gathered from actual experience. Perhaps it was not realized at the time that such anecdotes would eventually burst into print, but while the excellent dinner was appeasing the inner man the word was passed around that informality and spontaneity of expression would characterize the meeting, with the result that the shackles of convention were eventually cast aside and the meeting waxed better and better until the hour grew ,late, and the chairman, L. G. E. Bignell, originator of the idea, brought to a close what was agreed to be a profitable and entertaining evening. The ball was started rolling by Paul Ruedemann of the program committee, who offered the following:

Jan 1, 1929

By Waldemar Lindgeen

PART I.—General Features. PAGE Purpose and Extent of Inquiry ; Definitions (Fissure-Veins, Metamorphism, Metasomatism, Impregnation, Cementation, Weathering); Metasomatism in Connection with Mineral Deposits, Especially Fissure-Veins; Calcu lation of Analyses ; Criteria of Metasomatism; Crystallization of Sec ondary Minerals in Other Bodies; Secondary Alteration of Veins; Structure and Composition of Metasomatic Vein-Rocks and Their Rela tion to General Metamorphism,.759 PART 11.—Minerals Developed by Metasomatic Processes in Fissure-Veins. Quartz, including Chalcedonite and Opal; Rutile and Anatase; Fluorite; Calcite ; Magnesite and Dolomite ; Siderite; Muscovite and Sericite ; Biotite; Chlorite; Pyroxene and A mphibole; Garnet; Epidote ; Ortho clase ; Albite ; Tourmaline ; Topaz ; Kaolinite ; Zeolites ; Pyrite ; Mar casite ; Chalcopyrite ; Arsenopyrite; Pyrrhotite ; Galena; Zinc-blende and Other Sulphides; Tellurides; Native Copper ; Gold and Silver,. 601 Resistant Minerals,........... 619 PART III.—The Fissure-Veins Classified According to Metasomatic Processes. 1. Topaz-Cassiterite Veins (Altenberg and Zinnwald, Saxony ; Mt. Bischoff, Tasmania),..........620 2. Scapolite-Apatite Veins,.........625 3. Tourmalinic Gold-Copper Veins,.. 626 4. Biotitic Gold-Copper Veins,........ 641 5. Propylitic Gold and Silver Veins (General Features; Comstock Lode; The Veins of Nagyág, Hungary; Pachuca, Mexico ; New Zealand; Alaska ; Silver Cliff, Colorado; Silver City, Idaho),. .. .645 6. Fluoritic Gold-Tellurium Veins (Cripple Creek ; Other Occurrences),. 654 7. Sericitic and Kaolinitic Gold- and Silver-Veins (General Remarks; The Freiberg Veins ; De Lamar, Idaho; Summit District, Colorado),. . 6.58 8. Sericitic and Calcitic Gold-Silver Veins (The Gold-Quartz Veins of Cali fornia ; Idaho Types ; San Juan, Colorado ; Treadwell Mine, Alaska ; Gold Veins of Ontario, Canada; Schwarzwald Fissure-Veins),. . 664

Jan 1, 1901

For handling rough rock, the shovel-train system is unexcelled. The ideal application is a physically large, but not excessively deep, open-pit mine from which the coarsely blasted ore and waste must be transported distances in excess of three miles. If, in addition, a high production rate is to be maintained, railroad haulage will probably afford a lower cost per ton transportation than will any other haulage method. Relatively gentle grades must be employed- usually 3% for uphill hauls and 4% for downhill hauls. The greater the differences in elevation the greater are the railroad track grade space requirements. By way of illustration, a 3% ramp out of a pit only 300 ft deep must be almost two miles long. Mainline track locations should be selected carefully so that the frequency of movements during the life of the mining operation is minimized. This applies both to ore and to waste haulageways. Such moves are not only expensive but difficult to execute without adversely affecting production rates. The large mine affords greater opportunities for judicious location of semi-permanent trackage.

Jan 10, 1967

By S. J. Hruska, G. M. Pound

The critical supersaturations for appreciable nucleation rate of cadmium crystals on copper and glass substrates at 186°Kwere measured as a junction of thermal-beam energy over a range of source temperatures between 616" and 839OK. There was no effect of source temperature on critical super saturation. This implies that the adsmbate prior to nucleation is in thermal equilibrium with the substrate. THE deposition of metallic vapors on solid substrates has been found to exhibit a critical behavior in that the rate of formation of deposit increases markedly when the intensity of the vapor source is increased slightly.* Evidence of the ability of sub- where Je is the flux which would arrive if the substrate were equilibrated with bulk condensate at the adsorbate temperature. The following work was undertaken to test this hypothesis. A) Energy Exchange Between Metallic Vapor and Substrates. When a freely translating atom collides with a stationary solid body its energy and momentum undergo changes which determine whether the atom is reflected or adsorbed. An atom is considered to be reflected if it returns to a freely translating state after remaining under the influence of the body for only a time comparable to the period of oscillation of atoms on the surface. An atom which remains for a longer time is said to be in an adsorbed state. The parameter which describes the energy transfer occurring at the interface is the thermal-accommodation coefficient which may be defined in terms of energy as Ei = average energy of impingent atoms, Eeq = average energy of an emergent atom which has equilibrated with the substrate, and Eem = average energy of an emergent atom. If a temperature is assigned to each of these energies, we have at as defined by Knudsen.2 Since this allows no distinction between reflected and evaporated atoms, a more specific definition is introduced for the present purposes, namely 71 = probability that an impingent atom is transferred to an adsorbed state, aj = thermal-accommodation coefficient for reflected atoms, and aTc = thermal-accommodation coefficient for adsorbed atoms. During a time t,, the mean stay time, prior to evaporation the adsorbed atom (adatom) will interact with the substrate and this will have the net effect of transferring the adatom towards a state of

Jan 1, 1964

By C. E. Sims, G. A. Lillieqvist

The following presentation is more a summation of observations made and conclusions drawn over a period of three to four years than a report of experiments made with a definite objective. Tests were made, of course, to verify hypotheses, but the large mass of data was collected incidental to other work. Lack of space forbids the presentation of more than a few of those data. On the other hand, it is unfortunate that some of the most illustrative examples are not available. The work is admittedly incomplete but is presented in the hope that it will stimulate further work along a similar line. The answers to many of the questions left unanswered by this paper will be found only after long and painstaking study, such as is scarcely possible in a commercial laboratory where problems of immediate importance consume most of the time. It is also hoped that this study will in some measure throw light on some of the dark spots of steelmaking, and help to clarify some of the annoyingly vague references to "good practice." Only cast steel was studied and the conclusions apply to cast steel, but it is the authors' opinion that the quality of rolled or forged steel is largely dependent on the quality of the ingot, which is a casting. Although this discussion deals almost entirely with inclusions, it is important that the reader understand that only those natural inclusions which owe their origin to the solubility of certain materials in steel and to the chemical reactions of steelmaking are considered. Accidental inclusions, such as entrapped particles of slag, nozzle, runner, or mold arc outside its province and are not considered. Such accidental inclusions are always dangerous and should be carefully avoided. Relation between Ductility and Nonmetallic Inclusions In September, 1928, an acid electric furnace was put into operation at the Indiana Harbor plant of the American Steel Foundries. Following the usual practice, aluminum additions were made in order to obtain sound castings. Immediately the problem of low ductility arose. Previous to that time, only open-hearth steel was produced, and, aluminum being used rarely in that steel, there had been practically no trouble with low ductility in the lower carbon range.

Jan 1, 1932

By R. W. Heckel

A method is described whereby the relationship of both the "at-pressure" powder compact density and the "zero-pressure" compact density to the applied pressure may be obtained from continuous measurements of punch movement during a single compaction operation. The rate of density increase with applied pressure for the metal powders is found to be proportional to the volume fraction of pores for pressures exceeding a lower limit which varies from 15,000 to 30,000 psi, depending on the powder. 1 HE compaction of powdered materials is carried out primarily to increase the density of the material. If the ultimate goal of the over-all process is the attainment of minimum porosity, compaction is responsible for most of the densification. For example, loose powdered metals have porosities of about 65 to 75 pct. Axial loading in a die or hydrostatic pressure may effectively reduce the porosity of most powders to 20 pct or lower with pressures of 50,000 psi and greater. The relationship between the density of a powder compact and the pressure needed to achieve that density is most commonly obtained by pressing several compacts, each at a different pressure. Measurement of the densities of the individual compacts when they are removed from the die then provides the density-pressure relationship. However, this method suffers from several disadvantages. Because a large number of compacts and pressing operations are required, it is inherently slow. Furthermore, since density measurements are made after the specimens are removed from the die, data obtained refer only to pressures greater than those necessary to form a coherent compact. The third disadvantage is the inability of this method to provide information about the compact density at the applied pressure in the die. Because the determination of density-pressure relationships has been a slow, tedious process, investigators have sought to express the compaction behavior of powders by other means. The general terms "comparability" and L'compressibility" have been used to rank powders qualitatively according to their compaction characteristics. To restore a quantitative nature to the subject and to prevent confusion, Schwarzkopf1 has proposed that compac-tibility be defined as the minimum pressure needed to produce a given green strength, while compressibility should be used to indicate the extent to which the density of a powder is increased by a given pressure. Probably the most widely used of the compaction parameters is the "compression ratio,'' which is generally defined as the ratio of the compact density obtained by pressing at a given pressure to the apparent density of the loose powder.2 However, the description of the compaction behavior of a powder by these parameters provides only limited information about the process because of their applicability to just one specific condition such as a given green strength or a given pressure. The method of obtaining density-pressure relationships which will be described in the present paper was designed to eliminate the shortcomings of the previous techniques while maintaining equivalent accuracy and precision. EXPERIMENTAL TECHNIQUES The general principle employed makes use of the fact that the linear movement of the punch during a

Jan 1, 1962

By Yasushi Ishikawa

The fact that the degree of granulation and the state of granulated particles of sinter raw mixtures are the influential factors in ensuring coke combustibility and permeability during sintering has been clarified. Based on this knowledge, Nippon Steel developed the divided coke-addition process and the technology to utilize binder, and applied them on a commercial scale. Productivity and sinter quality are thereby greatly improved with a significant reduction in fuel consumption.

Jan 1, 1977

By Steven T. Mitchell

INTRODUCTION Mill production from the Homestake Mine in 1979 amounted to 1.29 Mt (1.43 million st) of ore containing 5.9 g/t of gold (0.172 oz per st) compared with 1978 production of 1.44 Mt (1.59 million st) containing 6.2 g/t of gold (0.180 oz per st). The average cost per ounce of gold produced in 1979 rose to approximately $250 contrasted with $176 in 1978. This increase in unit cost is the result of inflation, a diminishing ore grade, and productivity losses related to a shortage of experienced miners as well as compliance with federal regulatory requirements. Together, these factors prompted the investigation of several large-scale, highly mechanized underground mining methods. This analysis indicated Vertical Crater Retreat mining to be one of the safest underground methods known today, yet competitive with all other forms of stoping in terms of cost and productivity. Therefore, the feasibility of applying the VCR stoping method at the Homestake Mine was explored. Vertical Crater Retreat stoping is a recent innovation in large- scale underground mining based on C. W. Livingston's crater blasting theories. Figure 1 illustrates the method which consists of drilling 165.1-mm-diameter (6.5-in.) holes from a topsill down-dip to an under- cut on the level below. The bottom of each hole is then loaded from above with a predetermined charge weight and horizontal slices up to 4.27 m (14 ft) in thickness are blasted into the undercut. Broken ore is extracted from drawpoints located on or below the undercut level.

Jan 1, 1983

THE first session of the production engineering group on Wednesday, morning, with J. B. Umpleby as chairman, recorded the principal developments since the Fort Worth meeting. Added to this was a lively discussion of pressure maintenance. Recent advances in the air-gas lift have resulted from the need of applying the method to smaller wells at lower costs. In many places intermittent flow has given excellent results, and numerous mechanical de-vices for its automatic control have been, developed. Papers by C. V. Millikan on the Mid-Continent field and by A. H. Bell on California, fields formed the basis for discussion. The maintenance of initial sand pressures was ably discussed for two Texas fields by t. V. Foran in a paper that not only outlined the technic of operation and the results obtained but also contained noteworthy cost data in terms of increased ultimate production. Mr. Foran recommends the use of air in the first stages of pressure maintenance as a means of determining sand conditions and directions of flow, later turning to gas, if available, because of its greater solubility on oil. A round table discussion on petroleum engineering educational problems, with H. G. George as chairman, brought out much interesting discussion that is difficult to summarize. The other Wednesday morning session was a refinery engineering symposium with T. G. Del-bridge as chairman and the economical application of heat for the general topic. A paper on the modern pipe -still, by H. S. Bell, and another by C. W. Stratford on the modernization of the cylindrical still elicited a lively discussion.

Jan 3, 1928