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By C. M. Heath, B. W. Gonser

Soft solders are used principally in the automotive, can-making, building construction and electrical industries, but their field of usefulness extends well beyond these principal users to a vast list of miscellaneous applications where metal joints are required. The most common soft solders and the only ones considered in this discussion are those composed of lead and tin, with or without various relatively small percentages of impurities or additions. A small amount of antimony is often purposely added. As an indication of the importance of these lead-tin solders, 8620 long tons of tin were consumed in 1934 in the United States for making new solder, and during most of 1935 from 900 to 1000 long tons often were used each month. In addition, many thousands of tons of secondary solder are recirculated annually. A great many factors influence the properties of joints made with soft solders. Fluxes and the fluxing procedure used to prepare the surfaces to be joined in order to give a true metal-to-metal contact are among the most important of these factors. The temperatures used, cleanliness of the work and general soldering technique have their effect, but when results are unsatisfactory they are usually attributed to the metallic solder itself and the raw materials from which it is made. Sometimes criticism of the solder is justified. The wrong composition may be chosen for a given job, impurities may be present that ruin certain desired qualities, or uniformity may be lacking. A solder may even be looked upon with suspicion because of its ancestry, regardless of its true composition and behavior. To clarify the effect of slight differences in composition as found in commercially refined solders, a comparison of properties of solders grouped according to their origin has been undertaken. This investigation seeks to give practical information on the properties of tin-lead solders produced from virgin metals, from commercially refined secondary solder, and from an electrolytically refined crude

Jan 1, 1936

By Jun-Yan Chen, Stefan H. Boshkov

Metal mining in the People's Republic of China has shown great growth during the last three decades. Over 150 new iron ore mines and nonferrous base metal mines have been opened since 1949, althouc.11 most of them of medium and small size. Concurrently, many old mines were enlarged and reconstructed. The production of iron ore has grown from less than 1.5 million tons per year in 1949 to almost 76 million tons in 1978. A corresponding increase in the total annual output in the nonferrous metal mineral industry has also been noted. It is well known that the PRC is very rich in metal mineral resources. The reserves of tungsten, tin, antimony, molybdenum and iron ore are ranked in the top three in the world. Recently, some copper porphyry ore deposits were discovered in Jianxi and Anhui provinces. Some large nickel-copper sulfide deposits were discovered and have been developed in North- West China. Huge iron ore deposits have been found in Liaoning, Hebei and Szechwan provinces. However, the bulk of the iron ores are low grade. The growing metal mineral production has met basic domestic needs since 1949; it has also proven China's big resource potential. Mining methods have also undergone development in the past 30 years. About 80% of the annual output of iron ore comes from open pits, whereas about 58% of nonferrous metal ores come from underground mines. Blasthole open stoping, sublevel caving and induced block caving are widely used in Chinese underground metal mines (table 1). This paper summarizes in detail the planning for and application of these three bulk mining methods in the nonferrous and iron ore mines in China. CLASSIFICATION OF UNDERGROUND MINING METHODS The main principle of the classification of underground mining methods in PRC is ground support in the stoping cycles of the mining blocks or stopes. Table 2 lists this classification. It is essentially the same as that given in the SME Mining Engineering Handbook. Be- cause pillar removal is a secondary mining operation, using a variety of methods, they are not included in this classification. As is the case with most classifications in science and technology, there is no precise division between the classes of mining methods. Because of the rapid development of consolidated filling techniques in the past twenty years, some types of open stoping methods use fill in order to improve the ground conditions for the secondary recovery stage. Thus, these mining methods have features of both methods using no artificial support and those using artificial support. In this classification, this type of mining method is placed in the latter category. The shrinkage stoping method has been employed extensively to mine steeply dipping narrow veins of tungsten and tin in the Jiangxi, Hunan, Guangdong and Guangxi provinces. Shrink- age stoping is placed under the class of mining methods without artificial support be- cause this reflects the nature of the Chinese experience. The function of the broken ore serving to support the footwall and/or hanging wall is limited, because the expectation is for the host rocks to remain unsupported until the stope is drawn empty. APPLICATION OF BULK MINING METHODS Bulk mining methods consist of blasthole open stoping, sublevel caving and block caving. These stoping methods have much in common, such as: bulk ore materials blasted by long holes; higher production rates of stopes or blocks and higher production efficiencies of the whole mining systems.

Jan 1, 1981

By Donald C. Barton

Geophysical methods of prospecting taken as a whole do not seem to offer much promise to a young man planning to enter them in the future. They have come to stay, to be sure, and they will continue in at least moderate use for a long time. Domestic use of those methods presumably is at a maximum at the present time. Geophysical prospecting is expensive; the effects of the law of diminishing returns in efficiency in finding prospects can already be recognized. Small oil companies, independent oil operators, and royalty buyers have been doing much geophysical work. But in face of the increasing costs of discovery of prospects and in face of the probably decreasing favorability of the prospects discovered, I expect to see a sharp drop in their use of geophysics within the next 10 years. The major oil companies and the larger small oil companies will continue to use geophysics indefinitely, but it seems doubtful whether the very extensive domestic campaigns of a few companies will be maintained for many years, certainly not for 10 years. The use of the geophysical methods in foreign countries has not yet reached its peak, and probaby will continue to increase for several years. That peak level of activity will probably be held for 10 years, although the site of maximum activity will shift from country to country; by the end of 25 years from now, I should expect the foreign use of the methods to have leveled off to one-fourth to one-half the peak level. Foreign service in geophysics does not seem to offer an attractive career, except for men of exceptional disposition. Young men just out of college, who are willing and who can afford to spend three or four years having a fling at adventure before settling down, will find it attractive, but when their tour of foreign service is over, they probably will have harder work finding a job than when they were seniors, and their foreign experience will count for little, except for further foreign service. A few men, mainly the higher men, will have headquarters at civilized or semi-civilized cities and towns or at permanent oil-company towns, and can

Jan 1, 1940

By Donald C. Barton

Geophysical methods of prospecting taken as a whole do not seem to offer much promise to a young man planning to enter them in the future. They have come to stay, to be sure, and they will continue in at least moderate use for a long time. Domestic use of those methods presumably is at a maximum at the present time. Geophysical prospecting is expensive; the effects of the law of diminishing returns in efficiency in finding prospects can already be recognized. Small oil companies, independent oil operators, and royalty buyers have been doing much geophysical work. But in face of the increasing costs of discovery of prospects and in face of the probably decreasing favorability of the prospects discovered, I expect to see a sharp drop in their use of geophysics within the next 10 years. The major oil companies and the larger small oil companies will continue to use geophysics indefinitely, but it seems doubtful whether the very extensive domestic campaigns of a few companies will be maintained for many years, certainly not for 10 years. The use of the geophysical methods in foreign countries has not yet reached its peak, and probaby will continue to increase for several years. That peak level of activity will probably be held for 10 years, although the site of maximum activity will shift from country to country; by the end of 25 years from now, I should expect the foreign use of the methods to have leveled off to one-fourth to one-half the peak level. Foreign service in geophysics does not seem to offer an attractive career, except for men of exceptional disposition. Young men just out of college, who are willing and who can afford to spend three or four years having a fling at adventure before settling down, will find it attractive, but when their tour of foreign service is over, they probably will have harder work finding a job than when they were seniors, and their foreign experience will count for little, except for further foreign service. A few men, mainly the higher men, will have headquarters at civilized or semi-civilized cities and towns or at permanent oil-company towns, and can

Jan 1, 1940

By J. C. Deppe

A method is presented for calculating approximate injection rates in secondary recovery operations. The method can be applied to cases of unequal fluid mobilities, irregular well patterns and boundary patterns. The steady-state pressure distributions for the four flood patterns reported by Muskat and for five additional patterns reveal that most of the difference in pressure between the injection and producing wells occurs in regions around the wells which can adequately be described as regions of radial flow. This leads to a method of calculating injectivity by approximating the flood pattern with radial flow elements (or a combination of radial- and linear-flow elements for some patterns such as the direct line drive). Irregular and boundary patterns can also be approximated by radial and linear elements. Each of these elements can be described by radial-and linear-flow equations and the results combined as series flow resistances to give an approximate equation for the initial injection rate. The mobility ratio does not affect the initial rate; therefore, if the well pattern is one of those regular patterns for which theoretical rate equations have been derived for unity mobility ratio, the approximate initial rate equation can be improved by adjusting it to match the theoretical equation. The available theoretical rate equations are listed, including five new cases. As the flood progresses, the injectivity changes because in general the flood front will divide the pattern into areas of different fluid mobilities. Simple shapes can be assumed for the flood front so that both areas can be divided into radial- and linear-flow elements. Radial- and linear-flow equations are applied to these elements to account for the change in flow resistance behind the front. To calculate injection rates after breakthrough, it is necessary to know the sweep efficiency at breakthrough. Areal sweep data are available in the literature for a number of patterns, and sufficiently accurate breakthrough sweep efficiency can be estimated from these data if it is not otherwise available. Again, simple shapes for the flood front can be assumed after breakthrough, and injection rates can be calculated for the remainder of the flood. When areal sweep data are available, these data can be used to cbeck. the calculated injection rates after breakthrough. Injection rates calculated by this approximate method compare favorably with available model data. INTRODUCTION When the fluid mobilities in the swept and un swept regions are equal, the injectivity will not change as the flood front advances; and for regular patterns it can be calculated by mathematical formu1as.l When the fluid mobilities in the swept and unswept regions are not equal, the injectivity will increase or decrease as the flood front advances. In this case, the injectivity has not been calculated by analytical means for any practical well pattern; and, furthermore, scale model and analog4,6 results have been published only for the five-spot pattern. The main object of this paper is to present an approximace method for calculating injectivity for the case of unequal mobilities. The method can be applied to regular, irregular and boundary patterns. Before the approximate method is discussed, the analytical formulas for equal mobilities will be summarized, and the analytical solution for radial flow with unequal mobilities will be used to show how the injectivity changes as the flood progresses. EQUAL MOBILITIES, REGULAR PATTERNS In a flooding operation the injectivity, the rate at which fluid can be injected per unit difference in pressure between injection and producing wells, depends on basic physical properties and, in addition, on three variables to be treated here—the area of the swept region, the fluid mobilities in the swept and unswept regions, and the well geometry (pattern,

By M. G. Cheney

The purpose of this paper is to review the more important developments in the production of petroleum during 1930 in Texas, excluding the Panhandle and Gulf Coast districts, giving emphasis to trends rather than to statistics. Outstanding Developments Aside from increasing curtailment of drilling operations and general prorating of production by state authority the most noteworthy developments for the year appear to have been: 1. Demonstrations of the fictitiousness of potentials as shown first by Darst Creek pool, rated at 180,000 bbl. and having actually 78,000 bbl. daily, and especially by the Hendricks pool of Winkler County, with potential of about 1,000,000 bbl. daily in mid-year and production of only 52,000 bbl. daily when opened to continuous full production in December. 2. Rapid development of the Darst Creek pool under competitive drilling. 3. Orderly and highly successful development of the Van pool under unit operation. 4. Failure of several highly rated structures southwest and northeast of Van. 5. Extension of the deep Simpson production at Big Lake and increased interest in these pre-Mississippian pays in North Central Texas and West Texas. 6. Discovery of prolific wells in northwest Rusk County from sands of Upper Cretaceous age, portending a rapid and extensive development campaign around the northwest margin of the Sabine uplift. North Central Texas It appears logical to discuss the new developments by districts as set out by the American Petroleum Institute, but North Texas and West Central Texas districts will be treated together. Pre-Mississippian,.—The pre-Mississippian beds, which in previous years yielded a few large wells in Young, Cooke and Callahan counties,

Jan 1, 1931

By N. G. W. Cook

The conventional cyclic system of deep-level mining by drilling and blasting gives rise to an inadequate degree of stope sorting when mining thin reefs. This results in poor utilization of the capital facilities of a mine in the form of shafts, haulages, airways, and associated equipment. Continuous and controlled removal of the thin gold-bearing portion of the reefs would permit better stope sorting and hence greater utilization of capital facilities. Results of experiments to develop hard-rock cutting machines for mining are reported and the benefits which could be derived from their use are discussed. Mining, from exploration through refining, is essentially a process of sorting in which the payable mineral, or metal, is progressively separated from the other constituents of the earth's crust with which it was originally associated. This takes place more distinctly at each step of the operation. What is it that determines the degree to which sorting should be carried out at each of the several steps comprising a whole mining operation? The formal answer is that degree of sorting at each step which results in the lowest overall cost for the complete separation. In practice, individual steps are chosen from those available in current technology, each of which effects a degree of sorting such that the quantity of material which must be sorted in the succeeding step is economically acceptable. It follows that any new technological development has repercussions throughout the whole mining operation and, more important, that the solution to excessive costs in any one step of the operation may lie not in improving the costly operation itself so much as in increasing the degree of sorting preceeding that operation. This concept, particularly in relation to deep-level mining of thin, tabular gold-bearing reefs in South Africa, is discussed here, and the most recent results achieved in the development of hard-rock cutting machines for stoping more selectively than is possible with explosives are presented. Deep-Level Mining Deep-level mining involves operations which are either not encountered, or are of only trivial importance, in near-surface mining. Near-surface, the major operations are those of rock breaking, transport, and milling. In deep-level mining, hoisting, environmental control, and strata control assume major importance. Some idea of the relative magnitude of these operations may be gained by comparing the separate amounts of energy which are required, or which must be controlled, to effect the various operations when, say, mining a tabular deposit 40 in. thick at 8000 ft below surface, Table 1. It is true that the costs of handling a given quantity of energy are not the same for each operation. Nevertheless, Table 1 does emphasize the fact that the operations of hoisting, strata control, and environmental control are of unique and major significance in deep-level mining. In particular, hoisting and environmental control place a heavy load on the reticulation system of the mine—the shafts, haulages, and airways. Typically, a new, deep gold mine with an annual revenue of about $35 million requires a total capital expenditure of about $140 million of which some $100 million is invested in developing and equipping this reticulation system. The ratio between annual turnover and capital invested of about one-quarter is exceptionally low, and it typifies the poor utilization of capital by the current technology of mining hard rock at depth. The average thickness of the reefs in the new South African goldfields varies from 10 to 30 in.,l and even in the thicker reefs the gold is often confined within a small fraction of the nominal thickness. Nevertheless, it is universal practice to mine these reefs at a stope width of about 40 in. or more, so that the quantity of rock broken in the stopes and hoisted out of the mine is between two and ten times the quantity of rock actually carrying a significant amount of gold. The reason for the adoption of such excessive stope widths is to be found in the method of rock breaking by drilling and blasting. The only free surface to which a blast hole can break is the stope face. It follows2 that each hole cannot have a burden in excess of the height of the free face if it is to break satisfactorily. To

Jan 1, 1971

By E. H. Roberts, L. G. Swenson, F. C. Nix, R. A. Morgen

The binary system lead-antimony has been the subject of comprehensive investigations in these laboratories by Dean1 and his associates. The effect of a third constituent on this system, particularly on the lead-rich alloys in which dispersion hardening was found, has a commercial value as well as an academic interest. This paper covers the effect of the addition of copper, bismuth and tin, all of which are likely to be found in commercial lead-antimony alloys, and is divided into three parts, as follows: I. The System Lead-A~ili~r~ony-Copper II. The System Lead-Antimony-Bismuth III. The Lead Corner of the System Lead-Antimony-Ti11 These three systerrls are of three different types, and hence may be considered as covering three general kinds of additions. Bismuth forms no compounds with either lead or antimony and forms solid solutions with both. Copper forms several compounds with antimony as well as solid solutions but with lead it forms a two liquid layer system and no appreciable solid solution. Tin is soluble in both lead and antimony in the solid state and also forms a compound with antimony. The effect of small amounts of bismuth on the lead-antimony alloys is small, having no appreciable effect on the solubility of antimony. The temperature of the solidus floor is lowered appreciably by the presence of bismuth, cutting down the range of heat treatment. Copper, on the other hand, due to compound formation, increases the apparent solubility of antimony. The excess antimony is tied up with the copper finally and so is not available for dispersion hardening. The net result of addition of small amounts of copper is to shift the dispersion hardening peak of the

AN intermetallic compound, Ni3A1, has an ordered fcc structure of type Ll2, and shows peculiar dependence of the yield stress upon temperature; i.e., the yield stress increases by a factor of six upon raising the temperature from 77" to 900K1, 2 This compound is technologically important, since many nickel-base superalloys owe their high-temperature strength to the peculiar yield stress behavior of Ni3Al. The only study of the elastic behavior of this compound was made by Davies and Stoloff,1 who determined Young's modulus of poly crystalline Ni3A1 between 300" and 730°K. The determination of single-crystal elastic constants of Ni3A1 is therefore of interest in connection with dislocation dynamics and is reported in this paper. A single-crystal specimen, 1 by 1 by 3 cm, was cut from an ingot generously supplied by Dr. B. H. Kear of Pratt & Whitney Aircraft. Following initial machining with a Servomet and a surface grinder, the specimen was etched and annealed at 1100°C for 5 hr in vacuum followed by furnace cooling. Two parallel faces were oriented normal to within ±l deg of a [I101 crystallographic axis by the back-reflection Laue technique. The parallel faces were hand-lapped, etched, and polished by the usual metallographic procedures. Final thickness along the [I101 axis was (0.9325 * 0.0005) cm. Chemical analysis gave an average composition of 87.35 pct Ni. Total impurity content is esimated to be no more than 0.1 pct. The elastic constants were calculated from measurements of ultrasonic waves which were propagated along the [110] axis. A longitudinal wave and two shear waves whose displacements are aligned along the [ 110], [li~], and [001] directions, respectively, are necessary in order to completely specify the three elastic constants. Two 3/6-in. quartz transducers were bonded to the parallel faces of the sample with ~ac-seal.3 Although this bond was sensitive to thermal shock, it performed satisfactorily over the entire temperature range for both longitudinal and shear wave propagation. A frequency of 5 mHz was employed in the method of Williams and Lamb4 in order to measure the absolute value of the ultrasonic velocity. The pulse-overlap technique of Mcskimin5 was also used at this frequency in order to determine the shift in the ultrasonic velocity

Jan 1, 1970

By K. G. Davis

Dilute alloys of silzer in tilz haz been solidzjzed a1 controlled rules, in lzorizontal tubes 2 mrz and 0.5 rn in diam. Radioactive; tracer techniques we?-e used to study solute distvihutions along llze specimens and irmpurity substructures, as functions of the conditions growth. The results have heen mzalyzed using Burton, Prim, and Slichter's tnodel for the solute disty-ihution in the liquid ahead of an advancing solid-liquid interface. DECANTING techniques have been used to establish criteria for the formation of impurity substructure during solidification in several alloy systems An analysis equating the appearance of impurity substructure with the incidence of constitutional supercooling was developed,= in which diffusion was assumed to be the predominant mode of solute mixing in the liquid. Substitution of experimental data into the equations derived from the diffusion analysis gave reasonable values for solute diffusivity in the liquid. However, in these investigations solidification rates of 10 cm per hr and over were used, to minimize the effect of natural conection, whereas for crystals of high perfection lower solidification rates are needed, usually between 1 and 5 cm per hr. A knowledge of the conditions under which impurity substructures will be formed at low growth rates, and the degree of segregation to be expected, is therefore of interest. In the present investigation, radioactive-tracer techniques have been used to study the effect of growth rate, initial solute concentration, and size of specimen on the formation of substructure in uni- directionally solidified rods of dilute silver in tin alloys, over a range of growth rate between 0.5 and 10 cm per hr. Criteria for the formation of substructure were established by auto radiography. This was believed preferable to the decanting technique, for the relationship of the structure on a decanted interface with that of the freezing interface is not clear, since a layer of liquid is left on the surface following decanting.' The effect of substructure on the distribution of solute along the rods was also investigated. EXPERIMENTAL The procedure for sample preparation has been described in detail by einber. Alloys were prepared from tin of 99.999 pct purity and silver of 99.99 pct purity. A"', an emitter of both y and 0 radiation, was used as tracer. Samples of the alloys were drawn up into silica tubes with inside diameters 0.5 or 2 mm, remelted in a horizontal furnace, and solidified at controlled rates. A few centimeters of the samples were left unmelted for a measure of the initial concentration. Total sample length was approximately 20 cm. The temperature gradient in the furnace was kept constant at 36°C per cm in the region corresponding to the melting point for tin. To find how well this corresponded to the actual temperature gradient in the melt, a thermocouple of 38-gage wire was electrically insulated with a thin layer of Sauereisen cement and placed within one of the 2-mm-diam tubes, which was then filled with tin. The maximum diameter of the coated wire was 0.5 mm, the bead of the thermocouple junction being no larger than the diameter of the wire. A plot of temperature vs distance traveled by the furnace is given in Fig. 1 for a rate of furnace travel of 1 cm per hr. The temperature gradient in the liquid

Jan 1, 1967

By Hon. Abrams S. Hewitt

Gentlemen : If my first words were other than those of thanks for the high honor of being called to preside over the American Institute of Mining Engineers, I should do injustice alike to you and to my own sense of the obligation, under which I have been placed by your voluntary choice. When the position was first suggested to me, I resolutely declined to allow the use of my name, on the ground that, by training and occopation, I was not entitled to this honor, which, it then seemed to me, should be conferred only on a professional engineer. In fact, the history of the Institute, which had honored itself, as well as my distinguished predecessors, David Thomas, Rossiter W. Raymond, and Alexander L. Holley, by elevating then] to its highest office, seemed to indicate the line and the limit of safe precedent, in which I did not then see how I could be included. But my scruples were finally removed by the consideration that, as in the course of human industry, the pioneer, of whom Mr. Thomas was so marked a type, must precede the mining engineer, so fitly personified in Dr. Raymond, and be followed by the mechanical engineer, whose incarnation we behold in Mr. Holley; so all these must be supplemented by the man of affairs and finance, in order that "enterprises of great pith and moment" may be prosecuted to a successful issue. I felt, therefore, that I had no longer any right to resist your preference, or to deprive myself of what I must regard as the crowning honor of an active career. On an occasion like the present it seems appropriate to review the history in this country, during the last hundred years, of those industries which the Institute of Mining Engineers specially represents. There is much in the story with which other members of this body are more familiarly acquainted than myself; yet I fancy that to all of them, and not less to our distinguished and most heartily welcome gnests from abroad, a comprehensive outline of the progress of mining and metallurgy in the United States mill prove interesting. I ask your attention, therefore, to a condensed account of that subject, embracing a statement of the beginnings of the industry on our shores, of the notable events attending its increase, and of its present

By M. King Hubbert

In 1856 Henry Darcy described in an appendix to his book, Les Fontaines Publiques de la Ville de Dijon, a series of experiments on the downward flow of water through filter sands, whereby it was established that the rate of flow is given by the equation: q= - K(h2- h2)/I1 in which q is the volume of water crossing unit area in unit time, I is the thickness of the sand, h1 and h2 the heights above a reference level of the water in manometers terminated above and below the sand, respectively, and K a factor of proportionality. This relationship, appropriately, soon became known as Darcy's law. Subsequently many separate attempts have been made to give Darcy's empirical expression a more general physical fornzulation, with the result that .so many mutually inconsistent expressions of what is purported to he Darcy's law have appeared in published literature that sight has often been lost of Darcy's own work and of its significance. In the present paper, therefore, it shall be our purpose to reinform ourselves upon what Darcy himself did, and then to determine the meaning of his results when expressed explicitly in terms of the pertinent physical variables involved. This will be done first by the empirical method used by Darcy himself, and then by direct derivation from the Navier-Stokes equation of motion of viscous fluids. We find in this manner that: q = (N4(p/p)[g - (l/p) gradPI = WE, is a physical expression for Darcy's law, which is valid for liquids generally, and for gases at pressures higher than about 20 atmospheres. Here N is a shape factor and d a characteristic length of the pore structure of the solid, p and IL are the density and viscosity of the fluid, a = (Nd2)(pip) is the volume conductivity of the system, and E = [g - (l/p) grad p] is the impelling force per unit mass acting upon the fluid. It is found also that Darcy's law is valid only for flow velocities such that the inertial forces are negligible as compared with those arising from viscosity. In general, three-dimensional space there exist two superposed physical fields: a field of force of charucteristic vector E, and a field of flow of vector q. The force field is more general than the flow field since it has values in all space capable of being occupied by the fluid. So long as the fluid density is constant or is a function of the pressure only, curl E = 0, E = - grad F where F = gz + dp/p The field of flow, independently of the force field, must satisfy the conservation of mom, leading to the equation of continuity div pq = — f ap/at , where f is the porosity, und t is the time. For steady rnotion ap/at = 0. and div pq = 0 .

Jan 1, 1957

By W. F. Hosford, E. W. Kelley

Deformation studies have been conducted at room temperature on single crystals of magnesium and magnesium alloys with thorium and with lithium. Single crystals oriented to suppress shear on the easily activated basal slip systems were deformed by plane-strain compression. Compression along the C axis was accommodated by {1011} banding. Compression perpendicular to the unconstrained c axis activated {1012} twinning, and, after virtually complete twinning, deformation continued by {1011) banding in the twinned material. Compression perpendicular to the constrained c axis was accommodated by the simultaneous operation of (1012) twinning against the constraint and (1011 ) banding. Although this orientation was favorable for {1010)(1210) prism and {1011}(1~10) pyramidal slip, these modes were not observed in pure magnesium or in Mg-0.5 pct Th. However, {10i0)(1~10) prism slip was observed in crystals of Mg-4 pct Li during compression perpendicular to the constrained c axis. Fracture in all materials occurred parallel to (1124) or {l~il) depending on the orientation and composition of the specimen. THE mechanical behavior of the hcp metals is strongly anisotropic. Although several slip systems have been reported the slip is cpmmonly in the directions of closest packing, the (1210),' and this does not produce strains parallel to the c axis. Hence the inherent anisotropy. The deformation mode most easily activated in magnesium at room temperature is (0001)(1210)- basal slip. Also {1010}(1~10) prism slip and {1011)(1210) pyramidal slip have been reported, primarily at elevated temperatures.2"4 However, at room temperature the shear stresses to activate the prism and pyramidal modes are roughly a hundredfold greater than that required for basal slip.'j4 Thus prism and pyramidal slip may be expected only under special conditions of loading. Strains normal to the basal plane can be produced by twinning, however. Many twinning modes have been reported for magnesium,' with (1012) twinning the most common and relatively easy to activate. Magnesium can deform by (1012) twinning when stressed along the c axis jn tension, but not in compression. In contrast, (1011) twinning is activated by compression along the c axis and not by tension. In addition to primary twinning, secondary twinning or slip can occur within the reoriented material of primary twins.' In general at least five independent shear systems must be active to bring about an arbitrary shape change such as that in the individual grains of a deforming polycrystalline material.' Because basal slip can_ provide only two independent shear systems and (1012) twinning can only accommodate an extension of the c axis, other deformation modes must be active in magnesium for an arbitrary shape change to occur. The purpose of this investigation has therefore been to study the various deformation modes in magnesium at room temperature, with special emphasis on those modes that are less easily activated. The effect of the alloying elements, thorium and lithium, has also been investigated. In polycrystalline aggregates, unambiguous identification of deformation modes is extremely difficult and the direct evaluation of the resolved shear stresses to activate them is not feasible. On the other hand, uni-axial tension and compression experiments on single crystals may not activate some of the- deformation modes because basal slip and/or {1012) twinning cannot be suppressed in most orientations. However, it should be possible to activate all possible deformation modes using oriented single crystals and plane-strain compression. Identification of active deformation systems and evaluation of the resolved shear stresses required to activate them should be facilitated. Wonsiewicz and Backofen have recently completed an investigation of the plasticity of pure magnesium crystals at various temperatures utilizing plane-strain compression and selected crystal orientations. This technique has also been used in the present work. The seven orientations selected for study are indicated in Table I. Plane-strain compression along the c axis (orientations A and B) should activate some deformation mode _other than basal, prism, or pyramidal slip, or (1012) twinning. In orientations C and D, prism or pyramidal slip would be expected to take place. When the compressive load is applied perpendicular to an unconstrained c axis (orientations E and F) the three slip modes should be suppressed but not (10i2) twinning. In orientation G, basal slip should occur.

Jan 1, 1969

By Edward G. Norton

The salt deposits of the Mississippi Embayment region present a problem of origin so genetically related to the larger problem of the stratigraphy and structure of the region that a discussion of the one necessarily involves or assumes an understanding of the other. For this reason, I shall summarize briefly our knowledge of this region, emphasizing the facts related to the subject of this paper. In so doing I shall make liberal use of the reports of the National and State surveys. Geographically that section of the United States known as the Mississippi Embayment region represents a great V-shaped area, extending from near Cairo, Ill., to the Gulf of Mexico, and including Louisiana, eastern Texas, all that part of Arkansas bordering the Oua-chita and Ozark mountains, western Tennessee, Mississippi, and a part of Alabama. This great section Professor Harris has described as structurally a pitching trough, its medial line being well represented by the Mississippi River. Outcropping along the border of this area are the Cretaceous and Tertiary formations, unconformably laid down on the hard Paleozoic rock sheets that show more or less plication, deformation, and faulting, depending upon their proximity to the nearby major uplifts. East and west of the Mississippi River the Cretaceous and Tertiary beds dip river- and coastward at angles greater than the slope of the land. "Waters entering along the outcropping edges of the Tertiaries and Cretaceous and following bedding planes southward are soon thousands of feet beneath the surface." As the sedimentation of the region progressed, faulting and slips occurred along planes of pre-Cretaceous weakness. Whether these movements were genetically related to the loading of this V-shaped area, as Professor Harris seems to think, is a question still to be settled. The accompanying map, Fig. 1, was taken from Bulletin No. 7 of the Louisiana- Geological Survey. It shows the regional distribution of the salines, as well as an alignment of the domes, which has been assumed to indicate faulting.

Jan 1, 1915

By R. B. Gordon, D. A. Koss

Ultrasonic-atlenuation changes due to the formation of free dislocations have been observed during tensile tests of magnesium and LiF single crystals and samples of polycrystalline Results on the LiF and samples are similar: A preyield attenzration increase is observed which, however, be-corlzes smaller as the magnitude of the drop in load al yielding increases. This indicates that the yield point observed in these materials is due to dislovation rather than dislocation unpinning and that the initial density ' free dislocations must be low if the yield point is to be sharp,. Tests on the magnesium ere conducted at both 27" and 200C. Magnesium has the unusual property that the yield drop is larger at the higher test temperature and is accomplished by a decrease in attenuation. The latter is due principally to the temprovary pinning of detained dislocations by highly solute atoms. After strain aging., a stress as low as 0.3 bur suffices to unpin dislocations; microstrain measuements of sufficient sensitivity should. reveal plastic flow at stress levels this low IN another paper,' we describe the technique of simultaneously observing ultrasonic-attenuation changes and plastic microstrain during deformation of spher-oidized carbon steels. Changes of ultrasonic attenuation indicate damping effects caused by the oscillation of long, freely moving dislocation segments. Simultaneous microstrain measurements are used to indicate total dislocation motion. The dislocation-damping observations are most useful in the study of the early stages of deformation where the dislocation density is low and the plastic strain is small and relatively difficult to measure. Particularly interesting results are found in materials which display sharp yield points. Observations of these phenomena are reported here for three materials: single-crystal LiF and magnesium, and poly crystalline molybdenum. EXPERIMENTS Dislocation-damping effects were observed by measuring changes in acoustic attenuation with the ultrasonic-pulse method. The end faces of each of the specimens were ground flat and parallel and a quartz 10 Mc per sec, x-cut transducer was attached to one face. The bonding agents used were: a) "Nonaq" stopcock grease with magnesium, b) beeswax with LiF, and c) salol with molybdenum. With the LiF, the best acoustic signals were obtained at 45 and 50 Mc per sec; all other measurements reported are at 10 MC per sec. The Sperry Ultrasonic Attenuation Comparator2 was used to measure attenuation changes. In the

Jan 1, 1967

By Thomas P. Meloy, Duane T. Eppler

The science of particle shape analysis has expanded rapidly in the decade since precise numerical-statistical techniques were developed for use in characterizing the shape of closed forms. Use of Fourier descriptors permits shape to be quantified to whatever degree of precision is required. With this technique, particles and particle systems can be compared either on the basis of shape characteristics displayed by individual particles, or on the basis of aggregate shape characteristics representative of large samples of particles. Shape characterization work completed to date has shown that the physical characteristics of particle systems (porosity, permeability, strength, mechanical stability, chemical reactivity, and flow characteristics (viscosity)) are related directly to particle shape. Furthermore, it has been shown that particle shape is a function of chemical composition, process of formation, and post-formational history of the particle. In this light, particle shape analysis has potential applicability to a host of engineering and industrial problems encountered in processing particulate material. It can be used to optimize the efficiency of separation processes and particle feed systems, to trace particle pathways through processing systems, and to monitor the operation of specific processes, the wear of critical machine parts, and the quality of end products in processing systems. In this paper we discuss these specific applications of shape characterization to particle processing.

Jan 1, 1980

By William Clark

A bean placed at the bottom of tubing in flowing wells is not a new idea. In fact, a device which in effect was a bottom bean was patented prior to 1890 by John D. Rockefeller. Because of the limited use of the bottom bean, prior to 1922, when it was installed in a few wells in the Santa Fe Springs field, California, the knowledge of the results of its operation is very meager. Since then various oil operators have experimented with bottom beans, but most of the records of the results obtained by their use are unavailable. For the past year or two, more attention has been directed to this method of producing wells; the theory and best means of application have been studied, and accurate records maintained. In theory, the use of bottom beans in flowing or gas-lift wells should secure certain advantageous results. With the exception of flow friction of the tubing and flow lines, there is no back-pressure held on the rising column of fluid. Thus severe beaning is possible with no danger of killing the well by too heavy a fluid column, a condition that often exists when a surface bean is used. The whole energy of the gas expanding to atmospheric pressure is utilized to lift the fluid in the well. The same effect is obtained when flowing a well through open tubing or casing. In using a surface bean this energy of expanding gas is wasted into the flow lines beyond the bean, because the fluid has reached the surface by the time the restriction is reached and the work of the gas performed. The bottom bean affords an efficient use of the expanding force of gas, utilizing less gas to raise the same amount of oil, hence allowing for lower gas-oil ratios. The flow restriction being at the entrance to the flow string, a more uniform mixture of gas and oil enters the tubing and a steadier backpressure is held on the well. The uniform mixture and high velocity attained while flowing through the bean, which is above the critical velocity required to suspend a spray condition of gas and oil, prevent slippage of gas, surging and heading with its resultant strain on the casing. The advantageous conditions allow positive control of production in gas-lift wells within limits set by the bean size and amount of input gas; and probably help to prevent sanding up of a well and the coning

Jan 1, 1931

By C. A. Stewart

PAGE. I. Introduction............ 241 II. Location. TopoGRaphy. and History....... 243 III. DescRiption of the Rocks......... 245 1. Altered Sediments.......... 245 2. Alaskite........... 246 3. Alaskite.Porphyry.....255 4. Quartz Dikes........... 257 5. Biotite.Granite.......... 256 6. Quartz.Porphyryl......... 260 7. Andesite........... 262 8. Miscellaneous Dikes......... 263 IV. Age oF the Rocks and Comparison with other Localities.. 263 V. AlteRation............ 265 1. Sericitization........... 265 2. Silicification........... 266 VI. StRuctuRes........267 1. Dip of the Limestone......... 267 2. Faulting........... 267 VII. Contact - metamorhism,.......... 269 1. Endomorphism.......... 269 2. Exomorphism......... 271 Recrystallization and Loss of Color...... 271 New ,Minerals.......... 272 Addition of Material........ 274 Volume.Changes.... 276 Locus of Metamorhism........ 277 Method of Precipitation.........278 VIII. ORe-Deposits............ 278 1. Contact-Metamorphic Copper.Ores,..... 279 General..........279 Shape and Distribution........ 279 Minerals........... 281 Secondary Enrichment........ 282 2. Disseminated Copper.Ores........ 283 3. Origin of the Copper.Orcs........ 284 4. Lead-Silver Ores.......... 287 IX. Bibliography............ 288

Jan 1, 1913

By H. T. Matson

IN the Northern Rhodesia copper fields the size of the orebodies and the exceptionally consistent values over great distances made it possible to outline the ore with drill holes spaced at 1000-ft. intervals; in some cases, 2000-ft. intervals.. Owing to the fact that the size of the deposits made it very evident that much outside capital would have to be called in to develop them and, owing to the wide spacing of the holes, it was essential that the sampling of drill holes be as accurate as possible, so that outside examining engineers could adopt the results as trustworthy within the limits of accuracy of the drilling method. With this object in view, the field staffs of the Selection Trust group of companies have studied for the past three years, and are still studying, drill sampling in a very thorough manner, and for this reason it is felt that these notes may be of interest to engineers or students who are, or in the future may be, in charge of drilling operations. The orebodies in this field lie in shales and sandstones, more or less indurated, in the lower strata of the Roan series, and the copper mineralization is in the form of sulfides predominantly, with some oxidized copper minerals. Those interested in the geology and history of the area can find full details in a recent paper by Anton Gray and Russell J. Parker.1

Jan 1, 1930

By R. Norman Orava

The strain-mte behavior of. the tensile yielding and flow characteristics of arc-cast polycrystal-line molyhdenum of pidrity > 99.97 pct was investigated in the range 10-6 to 10-1 sec-1 at 243o, 293o, and 373oK for two grain sizes, 0.027 and 9.098 mm. For 0.998 mm, the strain-mte dependence of the lower yield stress can be described by a straight line of the jowl a, = a + 0 log e over the whole range of strain rates examined. However, for 0.027 mm, the data fit several consecutive linear relationships of the above form. The previous association of these different linear regions with different rate -controlling mechanisms is questionable for molyhdenzdm. The senlilog strain-rate dependence of the yield stress is consistent with Hahn's model for yielding when the stress dependence of the mobile dislocation density, pr, is taken into account. Since p', from rate -cycling experirnents, is found to be relatively insensitive to stress for single crystaIs, the obserzied log-log dependence of their yield stresses is also in agreement with the model. A correction for the stress dependence of p' changes the activation oolurrze for yielding from a zero to a more realislic inverse function of stress where the Peierls mechanism is believed to be rate-controlling. The gmin-size dependence of the lower yield stress is not a monotonic junction of strain rate. RECENT experimental evidence' has revealed that the strain-rate dependence of the tensile lower yield stress, a,, of commercially pure ni- obium and tantalum tested at room temperature can be described by several consecutive semilog relations of the form: sv =a + ß log € [1] where i is the applied strain rate and a and 0 are constant Over only relatively small ranges of strain rate. Three linear regions were found for niobium and four for tantalum. Each linear region was interpreted as being associated with a different rate-controlling mechanism on the basis of the current

Jan 1, 1964