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By R. J. Lloyd

INTRODUCTION The Mount Isa Mine is a large modern underground mine located in North-Western Queensland, Australia. Two ore types are mined and treated separately. Currently silver-lead-zinc ore is mined at the rate of 2.6 million tonnes per annum and copper ore at the rate of 4.6 million tonnes per annum. The silver-lead-zinc orebodies are mined by sub level open stoping and cut and fill methods whilst all copper ore is extracted by various forms of sub level open stoping. The mining operations are highly mechanised and utilise diesel powered load-haul-dump units of various sizes, two and three boom face drilling jumbos, electric-hydraulic rotary-percussive ring drills, in-the-hole hammer drills, rotary blasthole drills, raiseborers, battery/trolley locomotives, a large fleet of rubber tyred service and supply vehicles plus light rockdrills mounted on airlegs, rail mounted overshot shovels and battery and diesel powered locomotives. All stoping production ore is extracted with diesel powered load-haul-dump units. The ore is tipped into orepasses which connect to the main rail haulage levels. On the haulage levels electric battery/trolley locomotives are used to pull rakes of bottom dump or side dump trucks which feed the ore into primary crushers. Following two stage crushing the ore is conveyed to the shaft and hoistod to surface in bottom dump skips. Each ore stream has its own rail transport system, crushing stations and hoisting shaft feeding separate concentrators. This paper will consider some aspects of the role of equipment and machinery in the growth of the mine, will discuss in some detail the machinery and equipment in use today and will conclude with a look at some possible developments in mining equipment for the future, with particular reference to the Mount Isa Mine. A summary of mining equipment in use at Mount Isa is given in the Appendix. THE PAST Silver-lead-zinc ore was discovered at Mount Isa in 1923 and within a very short time many small mines were being developed. However the rich surface ore traces did not continue and by 1928 Mount Isa Mines Limited had acquired sufficient leases to plan for a large scale mine to exploit the low grade orebodies. At this early stage it was recognised that the mine would need to adopt the most mechanised mining techniques then available in order to overcome its twin disadvantages of low graaes and extreme remoteness. The Company introduced bar mounted drifters and overshot shovels to replace hammer and tap and hand shovelling in development work and by 1930 headings were advancing at the rate of 30 metres per week. In keeping with the concept of mechanisation the early engineers designed the Man and Supply shaft with a very large, for those days, cage compartment measuring 3.8 m x 3.4 m. This shaft was the main means of access into the mine for 36 years until the K57 shaft (now R62 shaft) was commissioned in 1966. Man and Supply is still in regular use. Production commenced in 1931 at an annual rate of approximately 660 000 tonnes of silver-lead-zinc ore. The mine was mechanised to an extent which was previously unknown in Australia; whilst the concentrator, smelter and power house utilised the most modern and efficient equipment available. Even so, the mine was very near to closure on several occasions and did not return a dividend to its shareholders for many years. Production levels remained at or slightly below 660 000 tonnes until a separate copper ore streani and mill was commissioned in 1953, doubling the existing production levels. The first underground crushers were installed at this time. Production rates expanded in the years between 1953 and 1973. By 1960 production reached 2740 000 tonnes of ore. In 1965-66 total production was 3650 000 tonnes and in 1973 the production rate plateaued at the current level.

Jan 1, 1981

By J. Chipman, N. J. Grant, E. C. Roberts

An equilibrium study was made of the distribution of chromium and oxygen between liquid iron, containing less than 1 pct Cr, and simple slags of the CaO(MgO)-Si02-FeO-Cr& type in the temperature range 1526' to 1734OC. The effects of slag oxidation, temperature, and basicity were observed. IN spite of the fact that chromium is one of the most important alloying elements in steel, and exists in almost all steels as a significant residual element, little research has been done to determine its behavior in basic steelmaking processes. Considerably more work has been done under silica-saturated acid slag conditions. Korber and Oelsen,' Herasymenko,' and others have generally agreed that in acid steelmaking practice the chromium in the slag behaved as if it were present as the chrom-ous ion (CrO). Work by Hilty- ir, high chromium slags also indicated that chromium may exist as CrO. In basic slag systems no equilibrium data exist. Based on individual studies of basic open hearth and electric furnace practice, Bardenheuer," Rock-rohr,% nd HauckQ oncluded that: 1—chromium recovery increased with decreasing basicity, and 2— chromium recovery increased with increasing temperature, although the effect was small. In similar studies Yavioskii and Dzemyen' concluded that: 1— slag FeO is the most important variable, 2—the basicity of the slag has no effect on chromium recovery, and 3—slag viscosity is not high even when 20 pct Cr,O, is present. Lapitskii\ oncluded that chromium recovery improved as the basicity of the slag decreased and increased with increasing manganese in the metal. Regarding the effectiveness of CrZ08 as a base or acid in basic slags, both Kristofferseno and Trojer" reported that Cr,08 was an acidic component requiring neutralization as 2CaO-Cr,O,. Experimental Procedure The experimental apparatus and procedure used for the present research were similar in most details to those used by Winkler and Chipman" and were described in detail by them. A magnesia crucible was used, holding 60 to 80 lb of Armco iron which was decarburized with hydrogen to about 0.010 pct C. Since all the metal samples solidified without gas evolution, this carbon level was assumed not to be significant. Synthetic slags made by mixing pure oxides were used throughout the study. Temperatures were measured by means of calibrated W-Mo thermocouples and were checked by Pt-Pt-Rh thermocouples. The range of temperatures covered in this study was from 1526" to 1734°C. The chromium content of the iron was in the range 0.032 to 0.82 pct, although the bulk of the tests showed 0.04 to 0.2 pct. The slags were of the CaO(MgO)-SiO,-FeO-Cr,O, type in which the Cr,O, content was from about 2 to 20 pct, although most of the slags showed from about 2 to 10 pct. The FeO range was from about 10 to 65 pct. CaO and SiO, were in the range of about 5 to 45 pct each, yielding a rather wide range of basicity values. The first 12 heats were made without a sulphur addition, and with only 30 min allowed for slag-metal equilibrium to be reached. In previous research it had been shown that less than 30 min was adequate to achieve equilibrium in slags free of Cr2O8.11,14.15 A study of the present data indicated that some of the tests may not have reached equilibrium in this time; accordingly four additional heats were made in which at least 1 hr was permitted for equilibrium to be reached. For reaching

Jan 1, 1955

By R. S. Rickard, M. C. Fuerstenau

Anodic polarization curves for iron dissolution and cathodic polarization curves for copper deposition and ferric and hydrogen ion reduction were studied. These results were used to predict the relative rates of the reactions: The rates of the first two reactions were found to be first order with respect to the reacting ion, and the rale-controlling step was diffusion of the ions to the callzode surface. The rate of hydrogen ion reduction in an oxygen-free solution is dependent on the reciprocal of the square root of the hydrogen ion activity. In solutions containing oxygen, the rate of hydrogen reduction becomes dependent on the square root of the partial pressure of oxygen. At equal concentrations copper precipitation occurs about twice as fast as ferric ion reduction. In an air-saturated solution containing 0.01 M cupric ion at pH 2, the rate of hydrogen ion reduction zs about 10 times slower than that of copper precipitation. At pH values below 3, the rate of hydrogen reduction in oxygen-free solutions is very slozu. COPPER cementation has been utilized industrially for many years as a means of recovering copper from aqueous solutions. There are many different types of cementation plants, but all simply provide a means of contacting iron with relatively dilute copper solutions. In the past little or no attention has been paid to rates or mechanisms of the reactions involved. As a result, this and other studies'-3 have been undertaken recently to establish the important parameters in this system. The reactions involved in copper cementation by iron are: Since transfer of charge is involved in every case, these reactions should be considered from an electrochemical point of view. In any electrochemical system involving electrolytic conduction, passage of electrons necessitates ion transfer to the respective electrodes according to Faraday's law. The current in the system will be proportional to the rate of ion transfer, and, therefore, when the current in the galvanic cell is known, the rates of the reactions involved can be determined. Galvanostatic electrode measurements5" are applicable for these electrochemical studies, in that with this technique polarization curves (current density vs electrode potential) are established by impressing a constant current through an electrode and measuring the electrode potential. Once the current density, electrode potential, and reacting area are known for each reaction in this cementation system, the rates of the iron-consuming reactions can be determined. EXPERIMENTAL MATERIALS Several metal electrodes were used in this investigation; they are shown in Table I. Solutions were made with reagent-grade salts and conductivity water. Air, nitrogen, and oxygen were employed. All of these gases were saturated with water and degreased prior to use. EXPERIMENTAL PROCEDURE The experimental work was divided into two general areas. The first area involved galvanostatic measurements, which were used to determine the rates of reactions as a function of various parameters. The second area comprised actual cementation experiments to check the rates predicted from the electrode measurements. Galvanostatic Electrode Experiments. Polarization curves were obtained using a standard galvanostatic technique5'= with the apparatus shown in Fig. 1. The various electrode polarization experiments were run the same way except for changes in solution composition, polarity, and type of measured electrode. The general procedure involved the following steps: 1) a solution was made 0.5 M in sulfate ion and to the desired cation concentrations; this solution was placed in a constant-temperature bath and saturated with the desired gas; 2) the electrodes were cleaned and placed in the electrode holder; 3) the previously cleaned apparatus was assembled and immersed in a constant-temperature water bath (temperature controlled to ± 0.05"C); 4) the electrode was then positioned; the solutions were introduced, and the polarization meas-

Jan 1, 1969

By T. L. Joseph

A study is made of the amount of solution loss necessary to maintain the reducing power of the gas stream in the blast furnace. Curves are presented to show the effect of solution loss, moisture in the blast, and carbon dioxide from the flux on the nitrogen in the THE blast furnace process is based upon the counter flow of gases and solids. As CO, N, and H, flow upward from the combustion zones, oxygen is acquired from the descending charge. In the reduction of iron ore, a portion of CO is converted to CO, and similarly a portion of H, is converted to water vapor. The inert N,, from the air used in combustion, passes through the furnace with little change. Its concentration is, however, decreased by reactions such as direct reduction and solution loss which increase the volume of CO in the gas stream; Similarly the evolution of C02 from the limestone also dilutes the nitrogen. he purpose of this paper is to illustrate an idealized and simplified method of studying furnace processes by following changes in the gas phase between the tuyeres and the stock line. A more specific objective is to evaluate the effect of solution loss upon the CO/CO, ratio in that region of the furnace in which FeO is reduced to metallic iron. This last stage of reduction requires relatively high CO/CO, ratios to exceed the equilibrium requirements. Solution loss or the reaction of COZ with C to produce CO has a pronounced effect upon the ratio of the carbon gases and is necessary to maintain the reducing power of the gas stream if the consumption of coke is low. It will be explained later that indirect reduction followed by solution loss is stoichiometri-cally equivalent to direct reduction. Calculations will be made to show how the composition of the gas in the region of the mantle varies with coke consumption and with different amounts of solution loss. Such calculations show the condi- tions under which gasification of C with oxygen in the charge is needed to maintain the reducing power of the gas. Equilibrium conditions for FeO and the carbon gases will be used to establish a minimum CO/CO, ratio below which reduction will not proceed. The manner in which carbon is gasified in the furnace, at the tuyeres with oxygen in the air or above the tuyeres with oxygen from the charge, will be a basic feature of all calculations. It is hoped that greater interest in the use of top gas as a means of following furnace reactions will be aroused by the calculations and generalized curves which are presented. Bosh Gas Equations Subject to some alteration by the amount of moisture in the blast and by direct reduction, the gas leaving the combustion zones of a blast furnace has a definite composition. Because a relatively small amount of oxygen is acquired from the charge in the bosh and in the crucible, the products of combustion undergo little change until they enter the shaft. Bosh gas is, therefore, essentially the products of combustion of carbon in a deep fuel bed with air. The relative weights and volumes of reacting materials are expressed by the equation: 2~ + 0? + 3.76N, = 2C0 $ 3.76NZ [I] Air Bosh Gas -air = 79% N? = 3.76) 21% 02 Starting with a known mass of C consumed largely by air, Eq 1, but partly by water vapor, Eq 2, the volume and C + H2O = CO $ H? [21 composition of the bosh gas can be calculated and subsequent changes followed as reactions take place at various elevations in the furnace. As shown in

Jan 1, 1952

By S. J. Matas, R. F. Hehemann, R. H. Goodenow

The hot-stage metallographic method has been employed to determine radial growth rates of upper and lower bainite. Lower bainite appears to grow as individual plates that increase in both length and thickness while upper bainite grows as sheaves of closely spaced plates or needles. A discontinuity in the temperature dependence of the growth rate appears to be associated with the transition from upper to lower bainite and stepped quenching experiments suggest that lower bainite will not continue to grow when the temperature is raised to the upper range. Thus, a single process does not appear to control the growth of both upper and lower bainite. A tentative model based on the forces acting on a dislocation interface is proposed to account for the slow growth of bainite. It has been recognized since the early studies of Davenport and Bain that a close relationship exists between the martensite and bainite transformations in steels. However, diffusion of carbon during the transformation has lead to considerable controversy concerning the reaction mechanism.1-7 Many studies4,5,7-9 have emphasized the structura and kinetic aspects of the bainite reaction and, in particular, the difference observed between the two forms of bainite—frequently termed upper and lower bainite. A kinetic difference between the two types of bainite has been revealed in the activation energy determined from the overall reaction;4,5 however, many difficulties arise in an interpretation of these activation energies since a number of temperature dependent factors contribute to the kinetics of the overall reaction. The displacive surface relief10 accompanying the bainite reaction permits a separation of the nuclea-tion and growth contributions to the reaction and allows the kinetics of the growth process to be examined. Several investigations of this type have been conducted; however, they have been restricted to the low temperature range.3'6'11 Here, bainite plates are observed to grow slowly in both length and width. The present investigation extends such studies to include the upper bainite range. MATERIALS AND PROCEDURE Materials. The composition of the steels studied in this investigation are presented in Table I. The range of composition permitted a study of the effect of carbon content on the growth rate of upper bainite in the 9 pct Ni steels and consideration of both upper and lower bainite in the higher carbon steels. These steels were received as hot-rolled rounds and were forged to approximately 1/2 in. thick plates for preparation of metallographic specimens. In order to produce an essentially zero carbon steel, Steel A was decarburized in wet hydrogen at 1550°F for 15 days with the result tabulated as Steel AD. Experimental Procedure. In order to study the slow growth of the displacive transformation product, a commercially available Leitz hot stage was modified to permit heating of the specimen by its own resistance in a manner similar to that employed by other investigators.6 The furnace chamber was maintained at a pressure of 2 to 3 X 10-5 mm Hg prior to austenitizing at 2000° ± 12° F for 5 min. Samples could be cooled from the austenitizing to the transformation temperature in approximately 15 sec and the progress of transformation was recorded with a 9 cm by 12 cm single frame camera or a 16 mm movie camera. RESULTS AND DISCUSSION Growth Characteristics. The general growth characteristics observed in this investigation were analogous to those reported previously.3,6,11 Typical growth sequences for the high temperature and low temperature forms are illustrated in Figs. 1 to 5. In both temperature ranges, bainite plates increase in length at slow, temperature dependent rates until interrupted by a grain boundary, another plate, or

Jan 1, 1963

By T. F. Mueller, P. A. Witherspoon

For the case of an infinite radial system operating at constant terminal rate, the reservoir engineer often uses the "point source" solution of the diffiusivity equation to study pressure interference effects. At early times and at short distances from the inner boundary these solutions are invalid. The amount of error is often not precisely defined because of mathematical difficulties. Work presented here shows that, if dimensionless time is defined appropriately, previous solutions of the pressure equation can be displayed .as a family of curves on one chart. These solutions include the point source solution (referred to in the field of hydrology as the Theis solution) and other solutions obtained with digital computer methods. With these curves, an exact evaluation of the pressure drop within a reservoir or an aquifer can be made by the engineer. Examples of field problem solutions are presented. In most reservoirs the error involved when the Theis solution is employed is often negligible; whereas, in the calculation of interference effects in an aquifer, a substantial error can occur through such an approach. INTRODUCTION Flow equations are used in petroleum engineering to study the behavior of individual wells and reservoirs. In the case of wells, the pressure response at the wellbore face is the major point of interest; whereas, in the case of reservoirs, the pressure response at the interface of the aquifer boundary is sought. To aid in such studies, the flow equations have been solved in terms of the behavior at these two inner boundaries. Only limited work has been published in regard to the pressure conditions away from these points, i.e., within the reservoir or aquifer. Theis and Mortada are among the few who have reported on this problem. The Theis approach employs the exponential integral and is valid for pressure conditions that occur some distance away from the flow disturbance. It is derived from the concept of a point source, as opposed to a flow across some finite area. The Mortada results, on the other hand, are valid at all points within the reservoir or aquifer. They are presented in terms of dimension less ratios of the radius where the pressure is desired to the radius where the flow rate is measured. Their main use, in the past, has been in aquifer studies. The published results are presented in the form of graphs that are limited to a maximum radius ratio of 64. These graphical results are cumbersome to interpolate at non-integral radius ratios, so that one may be forced to utilize a rather involved analytical expression presented by Mortada. BASIC EQUATIONS The solutions of Mortada and Theis are both based on the diffusivity equation as applied to the case of an infinite radial system subject to a constant terminal rate. The equation is obtained by combining the material balance equation with Darcy's flow equation. The assumptions implicit in the use of this equation are as follows: (1) a single fluid is present that occupies the entire pore volume; (2) the reservoir is horizontal, homogeneous, uniform in thickness, and of infinite radial extent; (3) compressibility and viscosity of the fluid remain constant at all pressures; and (4) fluid density obeys the equation Using the diffusivity equation in situations where the above conditions do not hold will result in errors. These errors (not discussed here) but only the errors which arise in the solution of the equation itself. The diffusivity equation for the homogeneous reservoir conditions cited above can be written in cylindrical coordinates, as To obtain a dimensionless equation, so a single solution can be used for applications of different porosity, permeability and fluid properties, the following transformations are usually made: After these transformations are made, Eq. 3 .can be written in dimensionless form, as MORTADA SOLUTION One solution of Eq. 6 has been given by Mortada.

Jan 1, 1966

By W. A. Tiller

The unidirectional freezing of a semiinfinite liquid from one end has been treated by calculating the solute and temperature distributions in the liquid and solid phases with time, when the solid-liquid interface advances at a rate proportional to (time)lt2. The nucleation probability for new grain formation is calculated as a function of the constitutional and thermal properties of the alloy, the pouring conditions and the catalytic efficiency of the nucleating agents. The transition from columnar crystal formation to equiaxed crystal formation is assumed to occur at a critical nucleation frequency for a particular alloy and the quantitative dependence of the ratio (columnar zone length/equiaxed zone length) upon the freezing conditions has been predicted. The effects of (i) fluid flow in the liquid, (ii) heat transfer through a mold wall, and (iii) a finite ingot length, have been explicitly tveated as departures from ideality. These departures from ideality are found to have very important consequences on the ingot stmcture. In Part I&apos; of this series, a qualitative description of the general ingot structure was developed. The factors that determine i) the ratio of the equiaxed zone length to columnar zone length and ii) the grain sizes in these zones, were discussed. In the present paper, topic (i) will be treated quantitatively, and it is intended that topic (ii) will be treated quantitatively in Part 111. The complete treatment has been split in this manner for ease of development and coherency of presentation. The treatments are quite mathematical in nature and, although some of the conclusions to Part 11 depend upon the treatment presented in Part 111, it was felt that the intended audience would find the material more readable and more useful in its present form. To this same end, it seems worthwhile to reiterate some of the qualitative aspects of grain nucleation during ingot solidification before embarking on the mathematical description. QUALITATIVE ANALYSIS In the conventional method of casting, a liquid alloy with a certain degree of superheat is poured into a mold. The outer rim of liquid metal cools rapidly to the liquidus temperature of the alloy and begins to undercool. As the degree of undercooling increases, nuclei of solid begin to form in this chill layer, this nucleation being catalyzed by certain heterogeneous particles in the liquid. The grains in the chill layer which are generally of random orientation, begin to grow inwards because of heat conduction through the mold. The grains usually develop a columnar shape since the frequency of nucleation of new grains in the liquid ahead of the advancing interface is generally insufficient to seriously impede the growth of the original grains. Due to the slow diffusion rate of solute in the liquid, a solute distribution is formed in the liquid adjacent to the interface which is either an excess or a depletion if the partition coefficient, ko, of the solute is < 1 or > 1, respectively. Thus, the liquidus temperature of the liquid adjacent to the interface is a function of position. The actual temperature in the liquid is also a function of position and the temperature gradient at the interface decreases as the interface moves away from the mold wall. Since the rate of advance of the interface decreases with time, the equilibrium temperature distributions and the actual temperature distributions as a function of interface position, X, can be illustrated as in Fig. 1. Thus, a region of liquid may exist in which the actual temperature is below the liquidus temperature. This liquid is contitutionally supercooled and therefore unstable with respect to the nucleation of new grains. Now, since the supercooling in Fig. 1 increases as the interface moves further away from the mold wall, the nucleation rate of new grains will increase. When the nuclea-

Jan 1, 1962

By A. F. Colombo, R. T. Sorensen, D. W. Frommer

An analytical method has been developed and used in batch and continuous tests to provide initial insights into the effect of soluble calcium ion in anionic flotation of silica from iron ores. A deficiency or excess of calcium ion in pulps subjected to this type of flotation produces an impairment in flotation efficiency. Data developed in the investigation are from a single ore, but show that total calcium requirement is met from water, ore and reagent sources. In batch studies, starch additions were shown to exert no influence on the calcium level, but fatty acid and sodium hydroxide had subtractive effects. The investigation was next extended to continuous flotation testing where the general observations from batch testing were confirmed. Factorially designed experiments were performed showing that the relationship of calcium additions to flotation response was not a simple one, but tended to shift to higher additions with increased fatty acid. Nevertheless, the range of soluble calcium levels measured remained fairly constant in areas of good flotation response. It is concluded that techniques developed should be useful in removing empiricism from flotation operations in this and other systems requiring activation for success. Further development should aid in process control both through methods outlined and through investigations aimed at studying the effects of other soluble reagents. Of the major mineral commodities, iron ore was one of the last to succumb to flotation processing. Commenting on this fact, one of the speakers 1 at the convention celebrating the 50th Anniversary of flotation in the U.S.A., said ". . . in 1951 froth flotation as a means of beneficiating nonferrous minerals was a might giant and could be characterized by &apos;you name it, we float&apos; - but not iron ore". This tardiness in applying flotation to iron ores was the result of a number of factors, including economics and ready availability of direct shipping ores. Even now, when the need for beneficiation can no longer be denied, proposals for flotation of iron ores are apt to be viewed with some misgivings. This disquiet results from knowledge that wide variability, which would necessitate corresponding adjustments in reagents, often exist within even a single ore deposit. Coupled with ore variability is the fact that, at present, there is no way of quickly and precisely anticipating the direction and magnitude of reagent changes required for uninterrupted production of acceptable concentrates. Despite the long delay, iron ore flotation is now practiced commercially, although the chief applications2-4 are to specular hematites having relatively coarse liberation and low slime content. In addition, the application of flotation in upgrading magnetic concentrates seems assured. However, these flotation methods do not appear applicable to substantial tonnages of fine grained, earthy, and frequently more complex semitaconites and nonmagnetic taconites. The U.S. Bureau of Mines, in devoting its attention to the semitaconite and nonmagnetic taconite class of materials, has demonstrated that anionic flotation of calcium-activated silica can be utilized with an expected high frequency of success.&apos; Even so, it has been recognized that the flotation method is a complex one, and that the reagent suite must be carefully tailored to the feed. These conditions would be expected to offer difficulties in treating ores with the wide range of variability previously discussed. Accordingly, research was initiated to develop methods to remove much of the empiricism from the flotation operation by measuring the reagent variables within the pulp for a correlation with flotation response. A simple illustration of the technique sought would be in the well established use of pH meters to provide feedback control to reagent feeders and thereby limit acidity or alkalinity to a range producing optimum results. The first efforts in this area have been concerned with measurements of soluble calcium ion. Bureau experience in both laboratory and pilot plant over the past five years has proved that the amount of calcium

Jan 1, 1965

By B. F. Decker, J. H. Keeler, W. R. Hibbard

Textures of hot-rolled, of cold-rolled, and of cold-rolled and annealed zirconium sheets were determined by use of an X-ray spectrogoniometer. All textures showed a tilt of the basal planes 240" from the rolling plane about the rolling direction. Deformation textures showed the [1010] direction to be approximately in the rolling direction. After recrystalliza-tion, the 111201 direction was approximately in the rolling direction. This texture was sharpened by annealing above the allotropic transformation. Textures of sheet produced by alternately cold rolling and then annealing were less strongly oriented than sheets that underwent severe deformation without intermediate anneals. THIS study of the deformation and annealing textures of high purity zirconium was carried out to supplement an investigation of zirconium and zirconium-base alloys. The spectrogoniometer method of pole figure determination was used and yielded more detailed and precise information than the photographic techniques used by previous investigators. Earlier investigations of the rolling textures of hexagonal metals titanium,1,2 beryllium," and zirconiumL having a c/a ratio slightly less than 1.6 disclosed a rotation of the basal planes from the rolling plane about the rolling direction so that the basal poles were inclined toward the transverse direction, and with one exception,& the [1010] direction was found parallel to the rolling direction. Similarly, hot rolling produced a spread of the basal poles in the transverse direction,2,3,5 With the [1010] direction parallel to the rolling direction. The textures of these metals after recrystallization differ somewhat from each other although still exhibiting the transverse rotation of the basal poles about the rolling direction. Zirconium" was found to have the [1120] direction in the rolling direction, beryllium" continued to have the [1010] direction in the rolling direction, and titanium&apos; was shown to have the [1010] direction in the rolling direction (the cold-rolling texture) when annealed at 1000°F, changing to the [1120] direction in the rolling direction when annealed at 1500°F. It was suggested2 that the titanium retains the deformation texture after re-crystallization, and preferred grain growth at higher temperatures produces the second texture. Annealing above the allotropic transformation temperature did not appreciably change the high temperature recrystallization texture for titanium.&apos; Coarsegrained zirconium showed more spread" in the transformation texture than in the recrystallization texture. The material used in this investigation was crystal-bar zirconium prepared by the iodide process. The major impurity was hafnium which was less than 0.3 pct. The composition obtained by spectro-graphic analysis is given in Table I. The hot-rolled specimen was prepared from a 50-g button of zirconium arc-melted in a water-cooled crucible under an argon atmosphere. This button was enclosed in a welded sheath of soft iron and the ensemble was rolled at 825°C. After each pass the sheath was put back into the furnace to allow it to return to the desired temperature. The zirconium ingot was reduced in this manner to a thickness of about 0.035 in., a reduction of approximately 90 pct. The sheet after removal from the sheath was alternately polished and etched to a thickness of 0.001 in. Cold-rolled specimens were prepared from crystal bar by a series of reductions of approximately 0.010 in. until the sheet reached a thickness of 0.010 in. after which it was cold-rolled to 0.001 in. thickness between sheets of alloy steel. The total cold reduction amounted to about 99.8 pct. Specimens were annealed in an evacuated Vycor or quartz tube. The transmission pole figures were obtained by the quantitative method of Decker, Asp, and Harker6 modified by Geisler7 using an X-ray spectrogoniometer with Cu Ka radiation. Unless otherwise specified all four quadrants were examined with 5" increments along the radius of the pole figure. Absorption corrections were made for changes in length of the X-ray path through the sample as inclination of the

Jan 1, 1954

By A. J. Griest, A. P. Young, P. D. Frost

A study was made of the effect of ß grain size on the tensile ductility of a-ß titanium alloys haet treated to strengths in the range 165,000 to 180,000 psi. It was concluded that the primary cause of $ embrittlement is the large grain size which is obtained so rapidly in many a-ß titanium alloys when heated into the ß field. It was also found that grain-boundary a and acicular intragranular a in the microstructure are not necessarily detrimental to the tensile ductility if the prior ß grain size is sufficientlv fine. BETA embrittlement occurs in a-ß alloys when the finish hot-working or stages of the subsequent heat treatment have been done at temperatures in the ß field. In order to avoid this embrittlement, for-gings must be finished at temperatures under the ß transus. For better workability, it would be desirable to forge at temperatures in the ß field. For this reason, research has been conducted to determine the cause of ß embrittlement. Although ß grain size has been considered as a possible contributing factor to ß embrittlement, only limited research has been done to evaluate its effect. The effect of addition elements on ß grain growth in unalloyed titanium has been studied by Liu.&apos; Complete mechanical property data, however, were not obtained for correlation with grain size. Ogden and coworkers2 have investigated the effect of both a and ß grain size and grain shape in Ti-Cr-Mo alloys. Their data indicated that tensile ductility was relatively insensitive to ß grain size at annealed strength levels (140,000 psi ultimate). No study has apparently been made to determine the relationship between ß grain size and ß embrittlement in a-ß alloys heat treated to high strength (180,000 psi ultimate). The high-strength condition is that in which ß embrittlement is particularly severe. Beta grain size is not easily varied through the use of a range of annealing times and temperatures in the ß field, because of the rapidity with which ß grain growth occurs. Short-time heating techniques are needed to obtain the smallest ß grains. EXPERIMENTAL PROCEDURE In this research, the experimental procedure was as follows: 1) Tensile and microimpact specimen blanks were resistance heated to produce a range of ß grain sizes. 2) The tensile and microimpact blanks were then solution-treated in the a-ß field and aged to produce predetermined ultimate tensile strengths in the range 165,000 to 180,000 psi. Tensile and impact ductility were then correlated with a grain size for constant strength levels. Materials—The alloys Ti-6A1-4V, Ti-4A1-4Mn, and Ti-16V-2.5Al are representative of the heat-treatable a-ß types in which ß embrittlement can be severe. The compositions and ß transi of the heats studied are given in Table I. The Ti-16V-2.5Al heat was melted and fabricated to 1/4 in. round at Battelle; the other alloys were obtained as 1/4 in. round rolled from commercial heats. The micro-structures of the as-rolled alloys were fine a-ß mixtures. This structure is typical of titanium alloys hot-worked extensively in the a-ß field. Resistance-Heating Treatments to Establish ß Grain Size—For direit resistance heating, a 1/4-in.-diam s~ecimen was heated with a 3000-watt transformer rated for 1000 amp with adjustable secondary voltage. The apparatus included a spray quench fixture. Both heating and quenching periods could be automatically controlled. For temperature measurements, 28-gage Chromel-Alumel wires were tack-welded to the specimen at its midpoint. A high-speed recorder-controller was used to control the heating cycle.

Jan 1, 1960

By Milton Williams

A comparison is made between the amount of interstitial water found by analysis in cores and that estimated from the resistivity curve of the electric log for the corresponding strata of producing reservoirs. It is shown that while the determined and the estimated water saturations are in good agreement in some cases, this agreement may be due to a fortuitous compensation of errors. Estimates of water saturations made from the electric 1og by use of existing relations should, therefore, be employed with caution. Also presented are data on the variation of salinity of interstitial waters in reservoir sands, and on the effect of variation of salinity and porosity on the validity of estimates of water content made from the electric log. INTRODUCTION Throughout the history of electric logging there have been recurrent cycles of optimism and pessimism as to the value of the electric log in the quantitative estimation of reservoir fluid content. The very early days of electric logging were an optimistic period, in which there was widespread faith in the ability of the resistivity curve to reflect fluid content, and in the ability of the potential curve to indicate textural characteristics. In time the accumulation of exceptions to this idealistic behavior brought about a general disillusionment, and caused the more pessimistic of those dealing with electric logs to believe that the sole importance of the log lay in stratigraphic correlation. Within the last several years optimism as to the quantitative use of the electric log has been revived, primarily as the result of the stimulating work of C. E. Archie&apos; on the estimation of interstitial water in sands from resistivity data. Even though the general trend of thought on the quantitative value of the electric log reflects optimism, it is inevitable that there are some widely divergent opinions of the validity of quantitative estimates based on the electric log. A valid method of estimation of fluid content by means of the electric log and a general knowledge of the textural character of the reservoir rock would be of signal importance, not only in that it would save time and money in securing information on reservoirs now being drilled, but also because it would permit the evaluation of reserves in many fields drilled without adequate core data subsequent to the advent of electric logging. Because of this importance, Humble&apos;s Production Research Division, in cooperation with various other company divisions, initiated several years ago series of tests designed to evaluate the reliability of estimates of fluid content made from the electric log. The investigation was limited at the outset to sand reservoirs, since it was felt that the inclusion of limestone reservoirs would entail needless complications. In devising these tests it was immediately apparent that the chief difficulty in evaluating the worth of any method of estimation lay in establishing the true value of fluid content. The results of direct analyses of cores cut with ordinary mud were not sufficient, because of the probability of contamination of the fluids by filtrate from the drilling mud; the results of restored state tests on cores were deemed unsuitable because these results can hardly be said to furnish a primary standard. The method adopted was the direct analysis of cores cut with an oil-base drilling fluid. Such cores, when properly handled, are believed to afford the most precise determination of water content available at the present, and, in addition, lend themselves readily to the determination of various other properties which are pertinent to the estimation of fluid content from the electric log. Since it was desired to compare the fluid contents estimated from the electric log run in ordinary mud with cores cut in the same hole, the use of oil-base fluid necessitated the changing over, after all cores were cut, to a conventional mud. This procedure presented several advantages, one of which was that the use of oil-base fluid permitted

Jan 1, 1950

By F. V. Lenel

Resistance sintering under pressure is a method of hot pressing in which a powder compact is subjected to pressure and simultaneously heated by passing a low voltage high amperage current through it. Equipment for this process is described. Its basic characteristics such as resistance requirements for powders and compacts, temperature distribution in compacts, and gas reactions during resistance sintering are discussed. Examples of the sintering process in compacts made of a single metal or an alloy powder and in compacts made of mixtures of powders are presented. Potential commercial applications of the process are evaluated. THE usual sequence of operations in commercial powder metallurgy is to compact metal powders in a die at room temperature and sinter the compact subsequently without applying pressure while the compact is in the sintering furnaces. In hot pressing, on the other hand, the compacting and the sintering are combined. The loose powder, or in many cases a cold formed compact, is inserted into the die which is held at the hot pressing temperature, the compact is left in the die until it attains its temperature, and then pressure is applied and maintained for a given length of time. The die may be heated by surrounding it with a suitable furnace, by high frequency induction heating, or by passing current through the die. In hot pressing, compacts of high density and good mechanical properties can be produced in a relatively short time. One of the principal difficulties in hot pressing is the lack of suitable die materials which will have adequate strength at the hot pressing temperature. This difficulty can be overcome at least partially by heating only the material to be hot pressed without heating the die directly. This can be done by passing a low voltage high amperage current through the material and simultaneously subjecting it to pressure. Either loose powders or compacts can be hot pressed by this method in which the desired temperature is produced by the power dissipated in the metal powder. This method of hot pressing has been termed "electrical resistance sintering under pressure." The most significant differences between this operation and conventional hot pressing are: 1—The sintering times are very short, usually a fraction of a second and at most a few seconds. 2—The powder and die are initially cold. 3—Heat is generated within the powder itself and not conducted in from the die. 4— The pressure used is high. 5—Cooling following sintering is rapid, amounting to a quench. Resistance sintering of metal powders under pressure has been suggested repeatedly. In 1933, G. F. Taylor&apos; proposed an apparatus which consisted of an insulating tube made of glass, or a ceramic filled with the powder to be pressed, and plungers above and below the powder. The powder was to be heated by passing an electric current through it and pressure was then applied. The apparatus was intended principally for hot pressing cemented carbides. Although the principle of resistance sintering under pressure is clearly shown in this patent, few details are given. A sintering period of a second or a fraction of a second, which is terminated by the operation of an inertia switch, is mentioned but no values for current density are mentioned. Low pressures, such as atmospheric pressure or a somewhat higher pressure exerted through a lever, are suggested. W. D. Jones&apos; discussed electrical resistance sintering under pressure and proposed using resistance welding apparatus for this purpose. In a patent issued in 1944, G. D. Cremera described a method of electrical resistance sintering under pressure using resistance welding apparatus which was to be applied mostly to nonferrous metals such as copper, brass, bronze, and aluminum. Current densities of 400,000 amp per sq in., sintering times of 1 and 2 cycles of 60 cycle current, and pressures of 5 to 10 tsi are proposed. Cremer suggested using an

Jan 1, 1956

By H. Kenworthy, R. B. Fisher, R. G. Knicherbocker, M. M. Fine

The progress made to date in the mineral dressing of complex Arkansas titanium ores is reported in this paper. Concentrates of rutile, a dioxide of titanium, were produced by treating a submarginal ore from the Magnet Cove Rutile Co., Inc., Magnet, Ark. The rutile recovery at present is 45 to 50 pct of the total TiO2, with the possibility of increased recovery with additional research. The work reported herein is part of a general study which will later include results of investigation of other titanium ore bodies in the Magnet, Ark., area. The fragile character of the rutile minerals, the softness of the gangue, the occurrence of pyrite and leucoxene, and the considerable proportion of extremely small size rutile in the presence of montmorillonite- and illite-type clays in the Magnet Cove open-pit mine are the important factors in the mineral dressing of this submarginal rutile ore. History The occurrence of titanium minerals in the Magnet Cove area of Arkansas was recognized as early as 1890, but it was not until about 1912 that any appreciable prospecting for the minerals was undertaken. At that time drilling was begun, a shaft was sunk, and several drifts were driven, but beneficiation to recover the titanium minerals was not attempted. The only successful mining and milling operation of the Magnet Cove rutile deposit was begun in 1932 by the Titanium Corp. of America and continued until 1942. The ore was washed by means of a rotary scrubber and then deslimed in a drag classifier. The discharge was ground in a rod mill, classified, and tabled to recover a rougher rutile concentrate, which was screen-sized and retabled on cleaner tables. The cleaner concentrates were given a reducing roast, screen-sized, and magnetically separated to produce a finished rutile concentrate. Most of the rutile produced during this period was sold abroad. In 1942, the Titanium Alloy Corp. of Arkansas (a subsidiary of the Titanium Alloy Manufacturing Co. of New York) purchased the property and rebuilt the mill. Subsequently, the plant and property were acquired by the Magnet Cove Rutile Co., Inc., of Little Rock, Ark., the present owners. Very little titanium has been produced since 1942. Although the Titanium Corp. activities yielded enough returns to allow continued operation for approximately 10 years, certain factors must be recognized. These are: (1) production of rutile in that period was during a low in the economic cycle which permitted low-cost operation on a small scale, and (2) a considerable portion of the production was above the water level and no drainage problems existed. Prior to this paper there has been no published report of any mineral-dressing investigation of the lower levels of the ore body. Reference is made in another paper1 to an earlier investigation of Magnet Cove rutile by the Rolla laboratory, in which it is stated that recoveries of 12 to 17 pct of the rutile were obtained. The present investigation was undertaken to improve the known milling processes and to provide adequate metallurgical information about the ore treatment. Titanium Technology The titanium mineral of primary interest in the present investigation was the titanium dioxide, rutile. Rutile is one of the industrial minerals whose annual consumption is relatively small but strategically important. The domestic production of rutile was 7100 tons in 1948. The imports of rutile in the same year were approximately 8000 tons.2 A major use of rutile is in the production of welding-rod coatings, for which a product containing a minimum of 92 pct titanic oxide is desired. Other constituents, such as lime, silica, and sulphur, must be held to a minimum, but hard-and-fast specifications for these elements cannot be drawn. It is necessary to incorporate the rutile in a welding-rod coating, make a sufficient number of test welds, and then determine the tensile strength of the weld metal in the as-welded and stress-relieved conditions. Such a test gives

Jan 1, 1950

By C. H. Li, R. J. Stokes, T. L. Johnston

The phenomenon of solid-solution strengthening has previously been studied in a number of binary alloy systems.1-8 There has been, however, very little information published concerning the strengthening effects of specific solutes in magnesium alloys. Schmid and his coworkers9,10 investigated the behavior of aluminum and zinc in binary and ternary magnesium-alloy single crystals, but this work was done before high-purity materials were readily available. Workers at the Dow Chemical companyH reported increases in the critical resolved shear stress upon alloying magnesium single crystals with zinc and indium. Recently, Hardie and parkins* investigated the extent of hardening produced by the addition of various solutes to poly crystalline magnesium. The present work was undertaken to provide data on the strengthening effects of a number of solutes in high-purity magnesium, for the purpose of supplying further experimental information which might be useful in describing a general mechanism for solid-solution strengthening. To simplify interpretation of the results, the mode of deformation was limited to basal slip, through the use of single crystals. EXPERIMENTAL PROCEDURE Magnesium and magnesium binary-alloy single crystals containing indium, cadmium, thallium, aluminum, and zinc were prepared in the form of l/2-in.-diam rods, approximately 8 in. long, using a modified Bridgman technique in which the crystals were slowly cooled from the melt in a steep temperature gradient, in an atmosphere of helium. It was found that a solid-liquid interface travel speed of about 0.7 in. per hr consistently produced single crystals. The poly crystalline starting materials for the preparation of single crystals consisted of 1/2-in.-diam extruded rods, prealloyed to the desired composition. The unalloyed magnesium and magnesium-indium extrusions were furnished by the Dow Chemical Co. The other alloys were prepared at the Rensselaer Polytechnic Institute Metallurgical Laboratories. Some preliminary studies of the strengthening effect of indium were conducted at room temperature using a constant rate of tensile loading of 1040 g per min. Stress was applied to the crystals by means of a simple 5:l lever arm. The lever was loaded by a constant rate of flow of shot into a receptacle suspended from the long arm of the lever. Plastic flow was detected by an electrical resistance strain gage cemented to the surface of the crystal normal to the minor axis of the predicted glide ellipse. The crystals were acid machined to produce tensile specimens with a reduced section between the grip ends, with an additional step in the center of the reduced section to compensate approximately for the slip-retarding effect of the strain gage. The balance of the single crystals were extended in an Instron tensile tester. This machine employs a synchronously driven screw and automatically records applied load as a function of cross-head separation. It became unnecessary therefore, to employ a strain gage to detect deformation or to acid machine a reduced section. Preparation for testing reduced merely to chemical cleaning of the surface, thus minimizing the amount of handling and probability of accidental damage to the crystals. The rate of elongation employed in all the tests was 0.002 in. per min, corresponding to a strain rate of approximately 0.0004 per min. EXPERIMENTAL RESULTS The investigation confirmed the finding of many workers that the yield strength of hexagonal metal crystals is strongly orientation-dependent. This is illustrated in Fig. 1, in which o, the tensile stress required to produce gross plastic flow in eleven unalloyed magnesium crystals stressed at a constant rate of loading is plotted as a function of sin X, cos Ao where X, is the angle between the

Jan 1, 1960

By G. S. Upadhyaya, A. D. McQuillan

HERE would appear to be a simple relationship between the group number in the periodic table of the early transition metals and the maximum amount of hydrogen which they can absorb.&apos; Thus group IIIA metals (Sc, Y, and La) yield a trihydride in which the metal atoms are on a fcc lattice and the hydrogen atoms occupy both tetrahedral and octahedral interstices. Group IVA metals (Ti, Zr, Hf) form dihy-drides in which the metal atoms are on either a fct or cubic lattice, but in which only the tetrahedral interstices are occupied by hydrogen atoms. In group VA (V, Nb, Ta) the hydrogen-saturated metal attains a composition slightly below that of a monohydride under normal conditions. Finally the metals of group VIA (Cr, Mo, W) do not dissolve appreciable quantities of hydrogen. The manner in which hydrogen solubility disappears on alloying a group VA metal with one from group VIA has previously been investigated.2 It is necessary, in order to obtain a general picture of the reactions of alloys of the early transition metals with hydrogen, to examine a system containing metals from groups IVA and VA in which there must be a change from a fcc to a bee hydride phase. The system chosen for investigation was the pseudobinary system between titanium hydride and niobium hydride. Metallic alloys were prepared by melting iodide-prepared titanium with zone-refined niobium in an argon-atmosphere are-furnace. To ensure homogeneity each alloy was cold-swaged and then heated at 1250°C in a high-vacuum furnace until metallo-graphic examination confirmed its complete homogeneity. Small weighed specimens of the alloys were charged with hydrogen using gaseous hydrogen generated by heating titanium hydride. The apparatus has been described elsewhere.3 Throughout the charging process the hydrogen pressure was kept at about 1 atm while the specimen, initially at 800 °C, was slowly cooled to 150°C over a period of days. The total amount of hydrogen absorbed by each specimen and the room-temperature crystal structure of the hydride powders were determined. The X-ray investigation indicates that the fee hydride phase arises from alloys extending in composition from titanium to 67 at. pct Nb. After a two-phase field lying between 67 and 74 at. pct Nb in which the fee and bee hydrides coexist, all alloys richer in niobium yield a distorted bee hydride. Data derived from parameter measurements are presented in Fig. 1. The atomic volume per metal atom has been plotted against the composition of the initial metallic alloy in order to facilitate comparison of the effects of hydrogen addition in the two phases of different crystal structure. The amount of hydrogen absorbed by each alloy at saturation in terms of the hydrogen to metal ratio and alloy composition is given in Fig. 2. Over the whole range of the fee hydride phase the hydrogen content remains constant, while in the distorted body-centred hydride phase, the hydrogen content increases with increasing titanium content reaching a hydrogen/metal ratio of 1.4 at the boundary of the two-phase region. It seems likely, therefore, that the maximum hydrogen content of the fee hydrides is limited to a hydrogen/metal ratio of 2 because hydrogen atoms

Jan 1, 1962

By T. E. Schmieman, J. E. Miller, M. L. Rizzone

Both centrifugal and reciprocating-type pumps have been widely used in the transport of slurries. Although with some limitations, centrifugal pumps may be used, especially for short-haul systems, however, for the long pipelines the reciprocating pumps are better suited. A state-of-the-art review is presented in which a discussion of applications is made and some of the problems associated with meeting the proper design conditions for satisfactory service are discussed. Several developments underway give considerable promise of better pumps in the future, although the current level of development provides for an economical means to move slurries. The movement of liquids in pipelines necessarily occasions the use of pumps. The petroleum industry is familiar with the transport of solids through mud pumps and cementing and fracturing pumps where the movement of slurries is an everyday matter. In the drilling of an oil well, the circulating fluid utilized to remove drill cuttings is called drilling mud. This substance is usually a fairly sophisticated material designed to develop certain characteristics desirable in the drilling process. The cuttings are suspended in a moving column of this fluid and brought to the surface. The separation of the cuttings from the drilling fluids is accomplished by the use of shaker screens and settling pits; however, it is impractical to remove the cuttings completely and as a result they are pumped through the mud pumps back into the circulating stream. Over the years, mud pumps have been improved so that rather long life can be obtained from liquid end parts subject to the attritional effects of the abrasive-laden fluid. It is from this background that reciprocating-type slurry pumps have been developed. Centrifugal Pumps Centrifugal pumps have also been used to transport solids, where low heads are required, typically up to 200 ft or so, and for short hauls. The centrifugal pump is a hydrokinetic device wherein the increase in velocity of a fluid stream is converted to head, and to achieve high heads a large change in velocity is necessary. Abrasive laden fluids cause wear on impellers and casings as a result of erosion by the fluid and the suspended particles. Centrifugal pumps, therefore, can only be used where the internal velocity of flow is rela- tively low. The advantage of centrifugal pumps is their high capacity at relatively low capital cost and usually relatively small space requirement. One of the disadvantages of the centrifugal pump when used in slurry pipelining can be seen in its typical pressure-volume performance relationship, which tends to work against the application (see Fig. I). If an increase in pressure (head) is occasioned by flow restrictions in the pipeline, say by the dropping out of solids, a desirable characteristic of a slurry pump would be that it develop increased pressure to overcome the restriction. The centrifugal pump provides the increased pressure only at the expense of considerably reduced volume which then results in a lower flow velocity. With the reduced flow rate, adequate velocity to hold the material in suspension and keep it flowing in the line might not be achieved. If centrifugal pumps are considerd for the movement of solids in a long line, a series of pumps must be staged in order to provide the necessary motivating force. A large number of pumps in the line would be required, since each of the pumps could provide only a small pressure increment. An equal number of standby pumps

Jan 1, 1971

By D. L. Albright, R. W. Kraft

Solidification experiments were conducted with the objective of testing the theory of eutectic colony formation. Appropriate control of variables in tests on a series of high-purity aluminum-copper specimens of eutectic composition resulted in the observation of three types of eutectic microstructures, these being a unique structure consisting of lamellae essentially parallel to one another, a banded structure, and the colony structure. Lamellar faults, which are morphologically similar in many respects to edge dislocation models in crystals, produced a complex substructure in these specimens. SOLUTE rejection at the advancing solid-liquid interface of a unidirectionally solidified single-phase metal can cause the liquid immediately in front of the interface to become constitutionally super-cooled below the equilibrium liquidus temperature. Constitutional super-cooling occurs if the solidification rate, R, is too rapid, or if the thermal gradient in the liquid at the interface, G, is too low. 1 This constitutionally supercooled layer in turn stabilizes a cellular rather than a planar interface.&apos; A similar cellular interface has been observed when lamellar and other types of eutectics were unidirectionally solidified, and it has been shown that the cellular interface led to the formation of eutectic colonies.&apos; The lamellar structure is fan-shaped at the edges of colonies (which correspond to valleys or grooves in the cellular interface) because the lamellae grow normal to the local interface. One of the possible mechanisms which might cause the formation of the cellular interface, in the case of solidifying eutectic alloys, is constitutional supercooling of the liquid with respect to a third component rejected by both phases of the eutectic.3,4 On the basis of the analogy between the solidification of single-phase metals and binary eutectics, a eutectic alloy should solidify with a planar interface if the ratio of G/R is sufficiently high to compensate for any impurity which might be present and causing constitutional supercooling. The fan-like microstruc-ture of eutectic colonies should not occur under these conditions and the lamellae should be parallel to one another and to the solidification direction for extended distances. The experiments conducted in this investigation were designed to test these ideas. Following a resume of the experimental procedure, the various microstructures observed during the study are described, and their relationship to the growth conditions which produced them is discussed. EXPERIMENTAL PROCEDURE The eutectic between an aluminum solid solution and 0 phase (approximate composition CuA12) was chosen for this work for the following reasons: it was known that a lamellar structure forms, the eutectic temperature is low enough to facilitate experimental work, and the components can be procured commercially in a very pure form. High-purity copper (est. 99.999 pct Cu, obtained from National Research Corp.) and spectrographic aluminum rods, having impurities other than copper estimated to be Zn-15 ppm, Mg-10 ppm, Fe-3 ppm, Na-2 ppm, Cd-1 ppm, and Mn < 1 ppm, were melted in a stabilized zirconia crucible in a vacuum induction furnace at a pressure of 10 pof Hg. The melt was superheated to about 1000°C to assure mixing, cooled to 780°C and cast into an investment mold which yielded sixteen cylindrical specimen blanks 1/2 in. in diam and 5 1/2 in. long. The casting was allowed to solidify under vacuum. This master heat had an analysis of 32.6 wt pct Cu and 67.4 wt pct A1 by difference. The cylindrical specimen blanks were remelted and solidified unidirectionally in an apparatus illustrated schematically in Fig. 1. An RF induction coil heated

Jan 1, 1962

By H. Kazemi

An ideal theoretical model of a naturally fractured reservoir with a uniform fracture distribution, motivated by an earlier model by Warren and Root, has been developed. This model consists of a finite circular reservoir with a centrally located well and two distinct porous regions, referred to as matrix and fracture, respectively. The matrix has high storage, but low flow capacity; the fracture has low storage, but high flow capacity. The flow in the entire reservoir is unsteady state. The results of this study are compared with the results of the earlier models, and it has been concluded that major conclusions of Warren and Root are quite substantial. Furthermore, an attempt has been made to study critically other analytical methods reported in the literature. In general, it may be concluded that the analysis of a naturally fractured reservoir from pressure transient data relies considerably on the degree and the type of heterogeneity of the system; the testing procedure and test facilities are sometimes as important. Nevertheless, under favorable conditions, one should be able to calculate in-situ characteristics of the matrix-fracture system, such as pore-volume ratio, over-all capacity of the formation, total storage capacity of the porous matrix, and some measure of matrix permeability. INTRODUCTION The analysis of flow and buildup tests for obtaining in-situ characteristics of oil and gas reservoirs has received considerable attention in the past decade. Most of the available techniques result in reliable conclusions in macroscopically homogeneous reservoirs or in the homogeneous reservoirs with only certain types of induced and/or inherent heterogeneity (such as wellbore damage, etc.). In general, the greater the degree of heterogeneity, the less the reliability of the information deduced from the pressure transient data. A commonly encountered heterogeneous system is a naturally fractured reservoir where two types of distinct porosities occur in the same formation. The region containing finer pores may have high storage and low flow capacities. This is called the matrix. The remaining region may have high flow capacity with low storage. The latter region is generally the set of interconnecting fractures and fissures of the rock, and for this reason it is called the fracture. Ordinarily, we wish to obtain the permeability and porosity of each region and perhaps the frequency of the fracture distribution in a reservoir. Such information is necessary for reservoir engineering. Other information, such as wellbore damage, will be useful in evaluating possible remedial work for such fields. Few authors have suggested theories to aid in calculating the in-situ characteristics of a naturally fractured reservoir similar to what we have described above. Pollardl suggested that a naturally fractured reservoir contained three distinct regions: a damaged or an improved region surrounding the wellbore, and the two remaining regions the same as described earlier. He suggested that the flow was taking place from the tight matrix into the highly conductive fractures, then into the we wllbore region and finally into the well column. He concluded that the average pressure buildup in each of these distinct regions can be expressed approximately in terms of an exponential decay function of time. He also hypothesized that the decay coefficients for each of these functions were significantly different from each other; consequently, each of these functions became dominant in turn, in the process of pressure buildup. Thus, by a proper graphic plot of the logarithm of wellbore pressure differences vs buildup time, each of these functions could be determined (see Fig. 1). Pollard suggested methods of determining the wellbore damage and fracture volume. Later Pirson and Pirson2 extended

Jan 1, 1970

By M. J. Hordon, M. A. Wright

ReCENT work has indicated that the substantial decrease in the rate of fatigue crack propagation for aluminum observed below a critical vacuum level can be attributed to the depletion of oxygen or water vapor from the vicinity of the fatigue crack opening.&apos; At reduced gas pressures, generally below 10-2 Torr with fatigue strain amplitudes in the range *1 to 2 x 10-3 and cyclic loading rates of 25 to 50 cps, estimated rates of oxide or hydroxide monolayer adsorption on newly formed crack surfaces can fall behind the actual rate of crack extension. Changes in the critical pressure required for the transition in fatigue behavior with changes in temperature, strain amplitude, and cyclic frequency can be interpreted from variations in the adsorption and crack growth rates.&apos;" Although the adsorption model generally appears to explain the enhanced fatigue resistance of reactive metals in vacuum, the specific adsorbing gas species and nature of the adsorption mechanism are uncertain. In addition to the direct dissociation and adsorption of O2 on the metal surfaces,3 the dissociation of H20 and subsequent adsorption of H ions have been advanced for aluminum alloys.4 The present note describes some measurements of the fatigue behavior of 1100 aluminum in reduced partial pressures of specific gases including O2, H2O, and H2 in order to provide additional experimental data. Cantilever-type specimens of 1100-H14 aluminum were fatigued in cyclic reverse bending at constant strain amplitude using a multispecimen vacuum apparatus and procedure described previously.&apos; After initial vacuum evacuation to 1 x 10-7 Torr, the appropriate gas species was bled into the system through a calibrated leak valve. The input rate was adjusted to maintain the desired pressure level under continuous evacuation, thus minimizing possible changes in gas composition during testing. High-purity input gases including 99.9 pct O2, 99.999 pct H 2, and water vapor from triply distilled H 2 O were used to provide residual pressures. Trace amounts of contaminant species were limited by passing the Oz and H 2 input gases through liquid-nitrogen-cooled copper coils prior to entry to the test chamber. Care was taken to repeatedly flush the gas lines and valves before testing to minimize the effect of adsorbed contaminants. Residual gas pressures in the range 10-6 to 5 x x3 Torr were monitored by an NRC ionization gage corrected for each gas species. In the higher-pressure range, 5 x 1CT3 to 5 x 10&apos; Torr, an NRC alphatron gage was used. In operation, eight simultaneous fatigue tests were conducted at a constant strain amplitude of *1.2 x 10 at cyclic bending rates of 25 and 50 cps to give an average fatigue life of 6.5x 105 cycles-to-fracture at standard atmosphere and 3.3 x 106 cycles in 1 x 10"7 Torr vacuum. Representative results for the effect of residual O2, H2O, and H2 contents on the fatigue life are shown in Fig. 1 for tests performed at 50 cps. It is apparent that the presence of either O2 or H2O gas in the system at partial pressures greater than 10"3 Torr was noticeably detrimental to the fatigue life. In contrast, the enhanced fatigue resistance typical of high-vacuum environments was retained with pure H 2 through the pressure range up to 1 Torr. For partial pressures of H2 gas above 1 Torr, the fracture life noticeably decreased. The critical Hz

Jan 1, 1969

By Howland Bancroft

AMERICAN investment in foreign mining interests today faces its greatest task. U. S. dollars must make possible the. steady procurement of the minerals our defense effort consumes in huge quantities. The two most vital factors involved in foreign procurement are time and the continued good will of the nations from which minerals are purchased. The Point IV program was formulated to care for the second item, but it has failed to do the job. Its lack of success has not been from intent or from basic failure in formula. Foreign Investment, Four Eras Foreign mineral development, in so far as participation by private capital from the United States is concerned, may be divided into four main chronological categories: First: The period prior to the first World War when people, capital and products moved with relative freedom across international boundaries, and London was the recognized mining seat of the world. By the end of 1919 the United States direct investments abroad amounted to $3.9 billion of which some $900 million were in mining and smelting and $600 million in petroleum. Investment climate throughout most of the world was excellent. Second: The period between the end of World War I, when the international economy had been shaken from its foundations, and the beginning of the great depression of the 1930&apos;s, which still further disrupted the world economy. By that time the world mining center had moved across the sea and the United States direct investments abroad had increased to $7.7 billion of which mining and smelting accounted for $1.2 billion and petroleum for $1.1 billion. Investment climate was good in most parts of the world. Third: The period of the depression of the 1930&apos;s and the beginning of World War II during which foreign trade was still further disorganized and the international economy collapsed. Nazi barter agreements were initiated in many parts of the world, and Soviet propaganda commenced to make its, influence felt in many countries. During this period United States direct investments abroad decreased to $7.3 billion. Mining and smelting investments during the same period decreased some $200 million, though direct investments in foreign petroleum areas increased an equal amount. Investment climate became less and less hospitable in all parts of the world affected by economic nationalism. Fourth: The period since the beginning of World War II during which total direct investments abroad increased from $7.3 to $13.7 billion. Of this sum, at the beginning of 1950 investment in foreign mining and smelting is reported to have been $1.2 billion-back to where it was in 1929, and in petroleum to have reached $3.7 billion. Investment climate remained favorable in the countries respecting contractual obligations and fair in their treatment of invested capital. [ ] As noted above, the relative freedom of passage across international boundaries by people, capital and products ended with World War I and the situation remains unchanged in a greater part of the world. While this same war upset international economy, the depression of the 1930&apos;s caused the collapse of world trade, and exports from all countries fell to an alarmingly low figure. Some countries almost ceased to export. Chile, for example, reported a drop of 88 pct in exports. Countries with

Jan 1, 1952