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By David Turnbull, J. H. Hollomon, J. C. Fisher

Understanding of the diffusion problem has recently been furthered by the analysis of Birchenall and Meh1.l They pursued the problem of the variation of the diffusion coefficient with composition for non-ideal solid solutions. Their analysis follows the tradition of Wagner,l Jost, Dehlinger, and Darken & who assumed the net flux of diffusing material to be proportional to the gradient of a quantity related to free energy. The basic assumption in Birchenall and Mehl's formulation of the problem is that the net flux of diffusing material is proportional to a thermodynamic activity gradient. To estimate the applicability of the derived relations, they corrected the diffusion coefficients of carbon in austenite by utilizing Smith's6 activity data for carbon, and the diffusion coefficients for zinc in copper with activity data computed from the vapor pressure measurements of Har-greaves.' The corrected coefficients for carbon were virtually independent of carbon concentration. For the diffusion of zinc in copper a moderate variation of diffusion coefficient with concentration remained after the correction. The problem of diffusion can be formulated in another way than that used by Birchenall and Mehl. The method is that of chemical rate theory and has been used by Eyring and his coworkers8,9 as well as by Eyring and Zwolinskilo in a discussion to Birchenall and Mehl's paper. As yet the method has not been applied to substitu-tional solid solutions. On the basis of their assumptions, Eyring and Zwolinski derived a relation between the diffusion coefficient and activity that is identical with that of Dehlinger and Darken but which does not correct for the variation of the diffusion coefficient with concentration as well as does the relation derived by Birchenall and Mehl. It was thought that the theory of diffusion would be more complete if the inconsistency between the two analyses could be rationalized and if diffusion in substitu-tional alloys were analyzed on the basis of the concepts of the chemical rate theory. Chemical Rate Theory According to the theory of absolute reaction ratess the reaction +..... +X, Eq I is viewed as taking place in two steps. First the reactants A1, A², . . . A; combine to form an activated complex M with which they are in equilibrium: A1 + A1+ . . . + A=M. Eq 2 Second the activated complex decomposes to give the products XI, XZ, . . . Xi: M?X, + X²+ . . . +Xi Eq g It has been showns that the number of activated complexes decomposing per unit volume per unit time is given by the expressiont kT -h CM † The transmission coefficient has been taken as unity.

Jan 1, 1949

By H. Kenworthy

This report concerns cooperative milling investigations of the Central mill of the Eagle-Picher Mining &. Smelting Co, The work carried on at the Central mill and the Rolla, Station shows that: It is possible to reduce the Central mill heavy-medium plant tailings by 0.05 to .15 percent zinc; the 3/16-inch to 10-mesh fraction of the jig feed can be treated by sink-float to obtain a tailing containing only half as much zinc as the jig tailing; Humphreys spiral concentration of the flotation tailing does not recover enough zinc to be economically attractive; and crushing and wet grinding of ferrosilicon for heavy medium are commercially feasible. The Eagle-Picher Co. operates extensive mines in the Tri-State area of Missouri, Kansas, and Oklahoma. The ore is milled at its Central hill, which also accepts custom ores. During the recent war the mill handled about 12,-000 tong- of low-grade ore per day. The company milled about 50 percent of the district tonnage and purchased nearly 90 percent of the custom ore. About 50 percent of the mill feed was from company mines. Zinc is the chief value in the Tri-State ores,-with Varying quantities of lead and cadmium minerals, as well as small amounts of germanium and gallium.

Jan 1, 1949

By Harry Gard Knox, F. R. Harris

This paper covers some of the problems presented to the oil industry in the drilling of oil wells in the open waters of the Gulf of Mexico. The hazards, delays and relative costs of offshore drilling are reviewed and various forms of drilling platforms discussed. The requirements of the offshore drilling rig are summarized together with the principal items affecting the cost of construction. Sea waves and their size and characteristics as affecting offshore platforms are reviewed. Drilling platforms are classified as fixed, or fixed and floating. Fixed platforms of the conventional cofferdam and pile-supported type are discussed together with their good points and their limitations. The desirability is pointed out of eliminating as much offshore work as possible where operations are subjected to constant and expensive delay and substituting therefor the prefabrication of structures ashore or in sheltered waters. Marked economy will come with the standardization of offshore rigs aid special means of transporting them to the site. Several types of structure which are partly pile-supported and partly buoyancy-supported are discussed and their possibilities of future usefulness commented upon. General Considerations The predominant attribute of offshore drilling equipment is that it must be equal to the job in hand. We therefore give first thought to the matter of adequacy. In view of the probable depth of drilling, the investment involved and the per diem labor costs, it is assumed heavy modern drilling equipment will be employed. In order to usc such equipment efficiently, the working deck must be ample in size and strength and supported so as to be relatively free from motion and from green seas even in heavy storms. These requirements necessitate a high and rigid land-based support for the drilling rig and machinery with plenty of space for supplies, such as pipe, mud, water and fuel, with reserves for days when transportation from shore is impracticable. In offshore rigs the crew will be housed onboard in comfortable quarters, probably air conditioned and equipped with a galley and refrigerated food storage. An important consideration will be the ability to transfer stores and crew to and from the rig in all but the heaviest weather and the platforms must be protected from the impact of supply vessels when alongside. It will be essential to maintain continuous communication with shore by radio or cable, not forgetting the possibility of a helicopter landing space for the transfer of crew and light stores as well as a means of general communication. Whatever structure is constructed must be secure from storms of hurricane force and a safe place for the operating crew to work. If the well comes in, the drilling rig will presumably be removed and a small but rugged pile-supported platform will remain to carry the Christmas tree with safe working space around it. It will be protected from damage on all sides by buffer piles or dolphins. It is assumed that the flowing oil will be piped to storage tanks in the vicinity of the well. An individual tank for each well or a

Jan 1, 1949

By Roscoe C. Clark

In October 1945. R. F. Farris. in an AIME paper entitled Method For Drtermining Minimum Waiting OIL Cenzent Time, presented a method for caiculating the minimum WOC* time required in oil well cementing operations. Briefly. this method consisted of shutting in a well. after the cement had been placed and noting the time required fur the wellhead pressure to reach a. maximum. This time was then multiplied by a factor of 1.5 to determine when the cement had reached sufficient strength to support the weight of the casing. As a result of this work, a number of areas have reduced their WOC time ~Wuirements with the subsequent saving of considerable rig time. The tests conducted by Farris were, for the most part, conducted under cementing temperatures in excess of 70°F. This was done because in the overwhelming majority of cases. cementing temperatures are in excess of 70°F (only in tile northern part of the country. primarily in the Rocky Mountain ares. in cementing surface casing are temperatures below 70° F. encountered, and such temperatures occur only during the winter months). The Stano-lind Research Laboratory since that time has performed a number of tests both in the laboratory and in the field to evaluate this WOC factor when cemeriting temperatures are lower than 70°F. The results of these tests indicated the need for greater WOC time in areas affeaed by abnormally low cementing temperatures. These tests indi.cated that a woc factor of 2 (Time from start to mix cement to maximum wellhead pressure x 2 = Time to drill plug) will allow sufficient time for the cement to develop adequate strength. A field test under abnormally low cementing temperatures (surface temyerature 35°F., mud discharge temperature <70°F. and cementing depth 500 ft.) in the Rangely Field, "* using the WOC factor of 2, indicated the time to drill the plug as 45 hours. Well conditions preventing getting back into the well until a 48-hour WOC time had elapsed. At this time, the plug drilled firm to hard indicating that the cement had reached its final set. It is contemplated that during next winter additional field tests will be performed to further check the results of the laboratory and field tests conducted to date,

Jan 1, 1949

By Frank R. Hunter

Introduction Scope of Work This paper represents the results of an investigation of the presence, amounts, and degree of concentration of heavy minerals found in the pulp of the phosphate flotation plant at Peace Valley, Fla., which is operated by the International Minerals and chemical Corporation of Chicago. In this paper, heavy minerals are those, excepting collophane, that sink in acetylene tetrabromide with a specific gravity of 2.95. Percentages of heavy minerals at several points of the flowsheet and the species of minerals have been determined. Some information as to the screen size of the minerals has been acquired. Previous Work All previous published reports or investigations of the deposits of heavy minerals in Florida have been limited to present beach sands. The mining operations conducted by the Humphreys Gold Corp. about seven miles east of Jacksonville along an ancient shore line have been described in trade journals, but descriptions of the minerals have been lacking. Commercial grades of ilmenite, zircon, and rutile are produced on a large scale. Papers have been published on heavy minerals found on the Florida beaches.1-6 Location "International&apos;s" Peace Valley flotation plant is in south-central Polk County, Fla. about eight miles south of Bartow and along the Atlantic Coast Line Railroad. The mine surrounds the plant and includes about 1500 acres of the phosphatic lands in this area. Geology General Setting All of the rock underlying the area is almost horizontal. The oldest bed exposed is part of the Hawthorn phosphatic limestone of Miocene age. This outcrops in the stream bed of the Peace River about one mile east of the plant. Elsewhere the Hawthorn is covered except where it has been exposed by mining operations. The Bone Valley formation of Pliocene age, which is the phosphatic stratum extensively mined in this area, unconforma-bly overlies the Hawthorn. Resting unconformably upon the Bone Valley formation are Pleistocene (?) terrace deposits of unconsolidated quartz sand which comprise the overburden of the phosphate ore. Stratigraphy Hawthorn formation: "Bedrock" of the pebble phosphate deposits is a cream to white colored, sandy, dense limestone containing varying amounts of small grains and nodules of collophane. The upper surface of the formation is undulating and irregular showing evidence of former

Jan 1, 1949

By L. S. Darken

It has been known for sometime that in an ionic lattice, such as that of Ag,S or FeO, the migration velocity of the anion may differ markedly from that of the cation, the cation being usually the more mobile. It has been shown, for example, that during the formation of silver sulphide tarnish on silver, the tarnish layer grows principally by the motion of silver cations through an essentially stationary silver sulphide lattice. Similarly, the growth of wüstite scale on iron proceeds principally by motion of iron ions, this being accomplished with the aid of vacant iron lattice sites into which the iron may readily move. Likewise investigations of solid solutions of various salts show that there is usually considerable difference in the mobility of the different cations. Measurements of the mobility of various metals in liquid mercury indicate that the various metals move at different rates relative to the mercury. In view of the foregoing it seems reasonable to suppose that when any single phase solution is acted upon by a field, the atoms of different elements respond in different ways; in particular, that the force arising from a particular concentration gradient in a binary alloy would cause the atoms of one component to move with a drift velocity which is in general different from that of the atoms of the other component. The recent experiments of Smigelskas and Kirkendall&apos; support this viewpoint, since they found, in essence, that during diffusion in alpha brass zinc moves appreciably faster than copper. This was evidenced by the relative motion of inert molybdenum wires. Such a phenomenon is incompatible with the place interchange theory of diffdsion proposed by several authors, most recently by Bir-chenall and Mehl.2 This theory has, however, also been questioned3v4 for other reasons, principally because of the high energy required for direct atomic interchange. The rather large difference between self-diffusivity, as determined by tracer technique, and mutual diffusivity, as determined with the aid of another element at low concentration, might also be interpreted as favoring the above idea; however. Birchenall and Mehl have pointed out that there is another possible interpretation of this difference; this is discussed later. A rather interesting and pertinent observation was made by Schwartz, who noticed that tungsten lamp filaments, heated by direct current, commonly fail by necking down in the region at the temperature gradient near the positive end, with a concomitant swelling at the corresponding position near the negative end. He introduces considerable auxiliary evidence to show that this phenomenon is occasioned by the motion of tungsten cations which migrate in the high temperature region from the positive end toward the negative end. The mechanism of this migration is not clearly understood. If, however, this experimental evidence be accepted, we are forced to conclude that alloying elements in the tungsten may migrate by the same or a Similar mechanism, whatever it may be, at a greater Or lesser rate, thus giving rise

Jan 1, 1949

By John W. Vanderwilt

The fluorescence of scheelite has been an important aid in recent years in the discovery and development of scheelite deposits. The use of fluorescence of synthetic compounds in industry, particularly in advertising, also has expanded greatly during the past decade. As a result, a number of new and convenient units for producing ultraviolet energy have become available, which have led to a greater application of fluorescence in the study of minerals. Studies have shown that the fluorescent color of a mineral may vary: (I) with the kind and quantity of trace elements, and (2) with the particular wave length of ultraviolet energy used. The wave length is dependent first on the type of generating equipment used, and finally on the filter employed to remove the visible light that may be present. A number of so-called ultraviolet lamps are listed and described, together with suitable filters known to be available. Scheelite fluoresces brilliantly with wave lengths of 2200 to about 3000Å., but not with longer wave lengths. The most convenient and efficient sources of ultraviolet for scheelite fluorescence are portable and laboratory units designed particularly for use with scheelite. So-called ultraviolet light globes of the photo-flood type emit wave lengths too long to cause scheelite to fluoresce. Attention is called to the minerals that fluoresce in a manner similar to scheelite, which necessitates a check test by means of characteristic physical properties. Chemical tests are the final authority both for identity and content of tungsten in scheelite ore. Introduction Recent development and extensive use of fluorescent lighting make it unnecessary to explain what fluorescence looks like. The fluorescent light tube is in reality a mercury vapor arc, which generates ultraviolet energy. Coating the inside walls of the tube is a substance, called a phosphor, that converts the ultraviolet rays to visible rays of light. In a like manner, certain minerals will transform ultraviolet energy to visible rays of various colors. The phenomenon of brilliant fluorescent colors cannot be satisfactorily described or reproduced photographically; a display must be seen to be appreciated. Only a few years ago fluorescence was regarded primarily as a source of entertainment, chiefly in spectacular displays of specimens in museums. The brilliant fluorescence of willemite, a zinc ore mineral, at Franklin, New Jersey, was utilized quite early in checking the efficiency of certain milling operations. Fluorescence has been used extensively in exploring for scheelite, as well as in mining this ore, during the past 10 years. The use of fluorescence in detecting scheelite, an important tungsten ore mineral, is well established, and much success has attended this new method; scheelite is a very inconspicuous white to gray mineral in ordinary light, but it

Jan 1, 1949

By Otto Ruhl

The zinc-lead ore reserves of the Tri-State district of Kansas, Missouri, and Oklahoma, as of December 31, 1947, are estimated at a total of 66,100,000 tons of crude ore containing 2.18 percent metallic zinc and 0.38 percent metallic lead. The Bureau of Mines began estimating the reserves in October 1945 and completed the&apos; work December 31, 1947. A total of 38,900 acres of land representing approximately 5 percent of the area of the district is covered in this report. The work was confined for the most part to properties developed or partly developed by drilling and underground workings, and to acreage sufficiently drilled out to indicate ore of enough tonnage to make a commercial undertaking. The acreage in which ore reserves exist is widely distributed in all three States. A map of the Tri-State area is shown in figure 1. The remaining 95 percent of the area is not necessarily nonproductive but represents, possibilities for future exploration and development of additional mineral resources when and if economic conditions or national necessity encourage such work. Of the total reserves, 41 percent are in Missouri, 38 percent in Kansas, and 21 percent in Oklahoma.

Jan 1, 1949

By S. Sillitoe

In mining, as in other business and engineering enterprises, efficient operation depends upon how well and how quickly the lines of communication can function. Mines have used the telephone on and between levels for many years, but in the hoisting shaft maintenance of physical wire connections for communication with the moving cage or skip has been found, for all practical purposes, impossible. A most natural solution was, therefore, the code-bell or buzzer signal system between fixed levels, and this has been standard practice throughout the mining world for many years. However, this system has serious limitations which make it impossible to signal a cage between levels in the shaft, and it requires crude, hazardous or costly methods for signalling during daily shaft inspection. Radio signalling overcomes these difficulties, because the communication medium is never broken and the cage-tender or shaft inspector can safely signal to, and receive signals from, the hoistman at any time from any position in the shaft, whether stationary or in motion. In addition to both audible and visual code signalling, two-way telephone communication and slack cable alarm are facilities made possible in recent commercially developed equipment.

Jan 1, 1949

By Clark Millison

The core recorder, a mechanical instr-ent for determining the exact depth at which core is recovered, drilled up or lost, is described. Examples of charts from the recorder are explained and interpreted. The uses of the core recorder are discussed. INTRODUCTION In the experience of geologists and engineers during coring operations on drilling wells, many will recall the times when a full core was not recovered and particularly when the requirement was urgent that they know exactly what part of the core was lost. To make this determination, the core recorder was designed. Its uses are many, and only the most obvious will be presented here. Although this discussion will be limited to drilling wells for petroleum, the core recorder can be used in any type of coring operation. The principle of the core recorder is the proportional reduction of the motion of core entering or dropping out of the core barrel to a stylus moving in such a manner as to record the reduced motion on a chart. The time element is registered on the same chart by the revolution of a clock which turns the chart drum. Thus the exact amount of core entering or dropping out of the core barrel is charted and the time of such entry or exit from the core barrel is precisely correlated to the depth at which the core is recovered or lost. Lack of movement of the stylus which is revealed by the continued revolution of the chart drum indicates that no core is entering the barrel. The principles are accomplished by an instrument placed inside of the core barrel. A cylinder which contains the clock and mechanical apparatus has a diameter smaller than that of the core barrel. Near the top of the cylinder is an eighteen hour clock which turns the drum that contains the chart. Near the bottom of the instrument is a serrated wheel which by friction against the inside of the core barrel is turned as core enters or drops out of the barrel.

Jan 1, 1949

By Louis C. Brichta

The rapid; depletion of&apos; known high-grade ore deposits in the Tri -State lead-zinc district and the recognized need for the development of additional reserves led the Bureau of Mines to make preliminary examination of sites possibly adaptable to low-cost open-pit mining methods. Abandoned mines whose ore deposits were known to have occurred at shallow depths naturally presented favorable test points for the development of possible open-pit orebodies. The Lone Elm mine was in this category.

Jan 1, 1949

By Jack D. Webber

The successful use of oil well packers requires, in part: an understanding of the pressures which exist at the packer in various applications and an understanding of the characteristics of the various types of packers. It is with these pressures, the resultant forces, and the characteristics of packers. that this paper is primarily concerned. An oil well packer may be defined as a mechanical device for blocking the passage of fluids in an annular space. In the more usual case, the annular space is that between the tubing or drill pipe in a well and the casing, and packers which block such an annular space are broadly referred to as casing packers. In the other case. the annular space is that between the tubing or drill pipe and the walls of an open hole, and packers for blocking this space are generally called formation packers. While the hydraulics involved are essentially the same for casing and formation packers. a greater variety of conditions are encountered in the use of casing packers and only casing packers will be discussed. After a packer has been set and a pressure seal effected between tubing and casing, the packer is comparable to a piston in a cylinder. Pressures acting upon a piston result in forces which will move the piston unless some means is provided to prevent such movement. In the same manner, pressures acting upon a packer will move the packer unless there is present a sufficiently great restraining force. PACKER CLASSIFICATIONS Packers may be classified according to the pressure conditions under which they are capable of blocking the annular space between tubing and casing. Fig. 1 shows schematically two types of packers in common use. These packers are capable of blocking the annular space against the passage of fluids under a differential pressure of significant magnitude only when the pressure in the annular space above the packing element is greater than the pressure below. It may be seen that in Fig. l-a. slips with teeth which bite into the casing and prevent downward movement are provided. In Fig. 1-h. an anchor prevents downward movement. In each case, there i-only the tubing to prevent upward movement when differential pressures act to move the packers upwardly. Packers which hold only a significant differential pressure acting downwardly have been in use since the early days of the oil industry and will hereafter be referred to as conventional type packers. In many packer applications operating conditions will 1.crult in differential pressures across the packer which will at times act to move the packer upwardly, and at other times, act to move the packer downwardly. For these applications, designs are available which will block the annular space and resist movement in either direction. Fig. 2-a shows schematically a packer of this type which is designed to be run into a well and set, and removed when desired by merely pulling the tubing. It will be noted that two sets of slips are provided-— one set above the packing element to prevent upward movement, and another set below the packing element to prevent downward movement. This packer is built around a mandrel which is essentially a part of the tubing. and which is free to move longitudinally within certain limits through the set packer. Fig. 2-b shows schematically a permanent type packer which is capable of holding pressures from either direction. Here again, two sets of slips are provided to prevenl movement of the packer. This packer is designed to become virtuallv a part of the casing when set and it is made of drillable material so that it may be drilled out when its removal is desired. The seal nipple shown effects a pressure seal between the tubing and the packer. This seal nipple is a part of the the tubing, and the nipple and tubing may be withdrawn from the well without disturbing the packer. It should be noted that these figures are not representative of all available packers which are designed to hold pressures from both above and below. Packers which resist movement in either direction will hereafter be referred to as universal type packers. There is a third type of packer in general use and this type is designed to block the passage of fluids when the pressure below the packing element ii greater than that above. This type is provided with slips which prevent upward movement of the packer and is somewhat similar to a conventional type packer run upside-down. Packers designed to hold pressure only from below are made in a variety of designs and are usually owned and operated by service companies.

Jan 1, 1949

By E. R. Brownscombe, Francis Collins

A study has been made of the material balance-fluid flow method of estimating reserves and degree of water drive from pressure and production history data. By considering the effect of random pressure errors it is shown that in a particular example a standard deviation of three and one-half pounds in each of ten pressure survey? permits the determination of the reserves with a standard deviation of 8 per cent and the water drive with a standard deviation of 15 per cent, assuming that certain basic geologic data are correct. It is believed that this method of estimating reserves and water drive is useful and reliable in a number of cases. The method is particularly valuable when reservoir pressure data are accurate within a very few pounds, but may also be applied with less accurate pressure data if a relatively large reservoir pressure decline occurs early in the life of the field, as for example in an under-saturated oil field. INTRODUCTION A knowledge of the magnitude of reserves and degree of water drive present in any newly discovered petroleum reservoir is necessary to early application of proper production practices. A number of investigators have contributed to methods of relating reserves, degree of water drive, and production and pressure history. 1-8 Three types of problems of increasing complexity may be mentioned. If a reservoir is known to have no water drive. and if the ratio of the volume of the reservoir occupied by gas to the volume of the reservoir occupied by oil (which ratio permits fixing the overall compressibility of the reservoir) is known, then only one further extensive reservoir property remains to be determined, namely the magnitude of the reserves. A straightforward application of material balance considerations will permit this determination. The problem becomes very much more difficult if we wish to determine not only the magnitude of the reserves but also the magnitude of water drive, if any, which is present. In principle, a combination of material balance and fluid flow considerations will permit this evaluation. Finally, if neither the magnitude of reserves, the degree of water drive, nor the ratio of oil to gas present in the reservoir is known and it is desired to determine all three of these variables, the problem could in principle be solved by a fluid flow-material balance analysis which determines the overall compressibility of the reservoir at various points in its history. The change in compressibility with pressure would provide a means of determining the ratio of gas to liquid present, since the compressibilities of gas and liquid vary differently with pressure variation. However, in practice this problem is probably so difficult as to defy solution in terms of basic data precision apt to be available.&apos; It is the purpose of this discussion to illustrate the second case, which involves the determination of two unknown variables, single phase reserves and degree of water drive, from pressure and production history and fluid property data, and to study the precision with which these unknowns can be determined in this manner in a particular case. Although an electric analyzer developed by Bruce as used in making the calculations to be described, numerical methods necessary in carrying out the process have been devised and have been applied for this purpose. Schilthuis,&apos; for example, developed a comprehensive equation for the material balance in a reservoir. He combined this with a simplified water drive equation, assuming that the ratio of free gas to oil was fixed by geological data and that a period of constant pressure operation at constant rate of production was available to determine the constant for his water drive equation. On this basis he was able to compute the reserves and predict the future pressure history of the reservoir. Hurst developed a generalized equation permitting the calculation of the water drive by unsteady state expansion from a finite aquifer. He showed in a specific case how the water influx calculated by his equation, using basic geologic and reservoir data to fix the constants, matched the water influx required by material balance considerations. Old3 illustrated the simultaneous use of Schilthuis&apos; material balance equation and Hurst&apos;s fluid flow equation for the determination of the magnitude of reserves and a water drive parameter from pressure and production history. He used this method to calculate the future pressure history of the reservoir under assumed operating conditions. As a basis for determining reserves, Old assumed a value for his water drive parameter and calculated a set of values for the reserves, using the initial reservoir pressure and each successive measured pressure. The sum of the absolute values of the deviations of the resulting reserve numbers from their mean value was taken as a criterion of the closeness of fit to the experimental data possible with the water drive parameter assumed. New values of the water drive parameter were then assumed and new sets of the reserves calculated until a set of reserves numbers having a minimum deviation from the average was established. The average value of- the re-

Jan 1, 1949

By R. E. Rick-Secker, W. M. Baldwin, R. McC. Baker

The development of residual stress in strip during rolling has not been systematically studied. A few scattered papers1 -3 mention the existence of residual stresses in rolled strip or touch upon some of their consequences,4 but there is no report of experimental studies in the literature describing the effect of roll diameter, strip thickness, reduction per pass, metal or metal temper on the magnitude of residual stresses developed in strip. A knowledge of the effect of these factors is of utmost importance since the present trend in some mills to roll thicker castings brings the rolling operation directly into that set of conditions which, as will be brought out in the present paper, can develop residual stresses of a high order of magnitude. Fundamentally, residual stresses are developed when a metal is inhomogeneously unloaded from a plastic stress state. A quantitative treatment of the problem requires a reasonably complete understanding of both the plastic stress state existing in the metal during deformation and the elastic stress state that would exist in the metal if the metal deformed as a perfectly elastic body. Our knowledge of either state during rolling is so meager that we can make no more than certain limited predictions. The external stress state* operating between the roll and the metal consists of Fig i—External stress state operating on metal being rolled (after siebel and LUEG5) compressive stresses acting almost perpendicularly to the strip surface but varying in intensity both across the width of the strip and along the length of contact between the roll and the strip. An example of such a stress distribution is shown in Fig I. The nature of the internal stress state, produced by this distribution, is not known. Various investigators,5-7 however, have felt that a qualitative similarity must exist between the internal stress state so produced and that produced in a wide strip that is compressed between two flat-nosed punches. In the latter case the external stress state is represented by a uniformly distributed compressive stress acting per-pendicularly over the face of the tool. The

Jan 1, 1949

By E. D. Gardner

Introduction Oil shale deposits have been exploited in various countries throughout the world, but generally with government aid. The oil-shale industry of Scotland perhaps is the oldest and best-known; the largest was conducted in Manchuria by the Japanese during World war 11 as a source of liquid fuels for military uses. In general, foreign oil-shale deposits that have been exploited are much lower grade than those in the western United States. Considerable interest began to be shown in western oil shales in 1916; the peak of activities was in 1923. The catlin operation, near Elko, Nevada, perhaps was the nearest approach in this country to an oil-shale enterprise on a commercial scale. Over 100 companies were formed, ostensibly for exploiting the oil shale; a large number of them, however, proved to be stock promotions only, which gave the embryo industry a black eye. The Bureau of Mines operated an experi-mental oil-shale retort plant near Rifle, Colorado, from September 1926 to June 1927 and again from April 1928 to July 1929, after which the plant was dismantled. By this time the East Texas oil fields had come ill and the country lost interest in substitute liquid fuels. During World War II the Nation again became concerned about the magnitude of its petroleum reserves. Congress (April 1944) directed the Bureau of Mines to build and operate demonstration plants to produce synthetic liquid fuels from coal, oil shales, and agricultural and other products; a five-year Program was authorized. *&apos; a part of this program the Bureau of Mines has built, at Anvil Points near Rifle, Colorado, a retort plant and develOped an experimental mine to supply the plant with oil shale. An important part of the mining work at Rifle is to devise methods and select practices for mining the oil shale on a commercial scale at the lowest practicable cost. The product to be mined has a relatively low value, a fact that must be kept in in mind. The combined aim of those in charge of the mining and those in charge of retorting is to demonstrate that the shale oil can be produced at a cost per barrel corresponding to the current quotation for crude petroleum —or at least very close to it. Plans call for an uninterrupted flow of broken oil shale from the lace in the mine, through crushers, through the retorts and thence to the disposal dump. The disposal of the spent shale in the Ride area should present no unusual problem. Mining research has consisted so far of Paper studies of the general phases of the probleml determination of the widest Span that the roof Stone will stand safely unsupported, and drilling problems. underground development has not proceeded far

Jan 1, 1949

Experimentation which measures differences in pressure across the interfaces of immiscible fluids in the interstitial spaces of porous media may be termed "capillary pressure experimentation". In the literature of petroleum technology since 1941 there have appeared twelve papers popularizing capillary pressure concepts and developing applications of these concepts for the solution of problems of practical reservoir engineering importance, such as the determination of connate water, fluid distribution. in transition zones, reservoir rock textural properties, and oil recovery from petroleum reservoirs.&apos; Although a review of the literature would be justified at this time in order to reconcile the conflicting viewpoints which are contained in the cited papers, the object of this note will be of more limited scope. It is believed that the recent paper of Muskat alls sufficient attention to many of the uncertainties which arise upon examination of the published literature. such that until satisfactory counter-proposals can be made it will serve our purpose only to mention some other like uncertainties. This will emphasize further the need confronting petroleum technologists to re. consider and reformulate the application possibilities of capillary pressure experimentation. In particular, I sug- gest that we examine the thesis that capillary pressure experimentation as above defined can lead to measurements reflecting the recovery of oil from petroleum reservoirs, as was proposed first" by Amyx and Yuster" and was first reduced to practice by the experimentation of Welge. In fact. I shall deal exclusively with the Welge papers since it is the principle one on this subject which has appeared to date. I shall attempt to show that the possibility of describing oil recovery features in terms of capillary pressure phenomena has not been established entirely. The Welge paper was a pioneering effort to evaluate this recovery application possibility. P. P. Reichertz&apos; comments on the Welge paper state that non-wetting phase discontinuities are developed occasionally in the Welge experiment, and restate Muskat&apos;s argument that discontinuous fluid elements (partially saturating the interstices of porous media which are elsewhere saturated with some other immiscible phase or phases) are not subject to the requirements of hydrostatic equilibrium. It is the purpose of my comment to show that it is unnecessary to make Reichertz&apos; postulation regarding non-wetting phase discontinuities (however valid) when it is desired to criticize welge&apos;s theoretical treatment of his problem. It can be shown that Welge&apos;s method of measuring values for &apos;&apos;capillary pressure" is invalid in many instances of application, such that his reported curves of capillary pressure Versus fluid saturation often have no physical meaning, even throughout the interval of fluid saturation where it might be otherwise suspected that no phase discontinuities occur. By considering established principles of capillary pressure experimentation it can be shown that the pressure difference experimentally observed between wetting and non-wetting fluid Phases which are contained in external reservoirs will reflect on the capillary pressure difference at the interfaces of contact between these phases only when the following conditions are satisfied: (a) There shall be a balance between the opposing forces of gravity and capillarity, as obtains under conditions of hydrostatic equilibrium when the positions of the interfaces of contact become fixed in pore spaces of certain geometry (b) The wetting and non-wetting fluids within the interstitial spaces shall everywhere be continuous with the external wetting phase reservoir and the external non-wetting phase reservoir, respectively. It will become apparent immediately that in any instance when a greater pressure is recorded in the external wetting phase reservoir than in the external non-wetting phase reservoir, one may establish either that static equilibrium has not been attained or that discontinuities in one or more of the fluids have been developed. This is because the pressure otherwiee is always ereatest in the non-wetting phase at each static interstitial interface of contact with the wetting phase. such that the externally measured pressure in the non-wetting phase likewise must be greatest if the above conditions are to be satisfied.

Jan 1, 1949

By W. T. Thom

All engineering education is faced by certain basic problems, three of which seem to have particular present importance in geological engineering training in general, and in respect to training for oil field geo-exploratory work in particular. Problem i The first of these problems has to do with present and future educational objectives and with the numbers and qualities of the men who should be coming out of our geo-exploratory training programs. Before the war we needed ever-increasing numbers of graduates at the Bachelor&apos;s level and a very much smaller number of men who had reached the Doctorate degree. Now, with more difficult, more extensive, and more costly exploratory work; with a rapid expansion of company "staff" activities, and with the initiation of many new research organizations and laboratories; it is clear that men of exceptional ability will be more and more in demand, and that the schools will need to carry a greater proportion of their students through to the Ph.D, degree. Problem 2 Assuming that the mineral industries will need an increasing supply of well-qualified Ph.D.s for future geoexploratory work (staff, line and research), can the schools expect to provide this supply of able Ph.D.s merely by expanding the proportion of B.S. and B.A. majors who go on through to the doctorate stage of training? And the answer is definitely "No"—as the situation stands at present. Most A.B. graduates are years short of the preparations in basic science and elementary engineering prerequisite to effective graduate study in the geoexploratory fields (paleontology ex-cepted), and similarly many of the annual crop of B.S. graduates lack adequate training in English; in ancient and modern history; and in the modern principles of labor and public relations. Indeed, several basic problems of undergraduate curricular organization and integration remain to be solved before most recipients of a Bachelor&apos;s degree will have that sound and broad educational foundation prerequisite to graduate training on a really effective basis. It is for these reasons that we have continued to experiment with our geological engineering program at Princeton, in an endeavor to provide a pilot-plant demonstration of a suitably broad and flexible undergraduate curriculum. Problem 3 But assuming that the schools can and do get undergraduate curricula set up in proper phase and scale to meet needed enrollment quotas for graduate training, what about the most urgent part of our whole mineral-industry educational problem? What about finding and bringing into mineral-industry training those youngsters of superior ability who are, by potential or known inclination, especially well-qualified for geoexploratory work?

Jan 1, 1949

By C. H. Frick

Before presenting the main topic, as indicated by the title, this paper will give some of the high-spot history of the anthracite industry. Introduction The earliest recorded use of anthracite was in the year 1762, when a company of Connecticut pioneers discovered anthracite near the present city of Wilkes-Barre, Pennsylvania. In the early days of the industry, the coal was used only in large pieces, the smaller pieces being discarded to waste piles. As the output of the industry increased during the nineteenth century, uses were developed for somewhat smaller sizes down to and including pea coal. Early in the twentieth century, sizes smaller than pea, such as No. I and No. 2 buckwheat, were developed and used. Accumulations of piles from current mining operations were still increasing; that is, the smaller sizes were still being discarded. It was not until after World War I that preparation of the so-called steam sizes began commercially. This was largely No. 3 buckwheat, which is screened through a 3/16-in. round-hole screen and over a 3/32-in. or a 1/16-in. round-hole screen. Use of Smaller Sizes The earliest recorded experience in burning the small sizes of anthracite for steam production, other than in a previous small experiment, was in the year 1913, when a size known as "boiler fuel" was introduced—a mixture of rice and barley (No. 2 and No. 3 buckwheat). At that time, there was still no method known for burning the still smaller sizes. At the present time, various sizes down to and including No. 5 buckwheat are being prepared (Table I) from current mining and bank-reclaiming operations. The sizes of No. 4 and No. 5 buckwheat and smaller are generally being used for steam production in large boilers. The Pennsylvania Power and Light Co., following World War I, used 680,000 tons of anthracite per year, burned largely on stokers for production of steam, whereas for the year 1943 it used 1,940,000 tons of stoker sizes and 400,000 tons of smaller sizes for grinding and burning in pulverized form. This company has taken a very large part in the research and development of ways and means of burning these smaller sizes of anthracite, including the grinding of the very small sizes. This paper is particularly concerned with the latter feature.

Jan 1, 1949

By K. D. Watson

"THE Mindamar zinc-lead-copper mine, owned by Mindamar Metals Corporation Limited, is at Stirling in Richmond County, near the south-eastern shore of Cape Breton Island, Nova Scotia (Figure I). It is connected by several roads with the Canadian National railway at Sydney and St. Peters.The deposit is said to have been discovered around 1895 as an outcrop in the bed of Copper brook, but the details are obscure. Not until 1925, when it was optioned by American Cyanamid Company, was it developed underground. Between 1927 and 1938, the 1-nine was operated intermittently by The British Metal Corporation (Canada) Limited, and yielded approximately 200,000 tons of ore averaging about IO per cent zinc, 2 per cent lead, I per cent copper, and small quantities of silver and gold. In December 1950, Dome Exploration (Canada) Limited made an agreement with Mindamar Metaî Corporation Limited, which was exploring the old mine, to assume management and prepare the property for production. Production started in April 1952 with a new mill and a new four-compartment shaft, and between that time and the end of 1954 it has totalled 545,347 tons of ore averaging 5·89 per cent zinc, 1·35 per cent lead, 0·66 per cent copper, 0·032 oz. gold, and 2 151 oz. silver.The Mindamar orebodies are irregular lenses and large veins lying within a wide, almost vertical shear zone of remarkable persistency. The shear zone consists mainly of well-foliated sericite schist derived from siliceous siltstone, and it contains a vast amount of dolomite and magne-site of hydrothermal origin. Most of the ore is extremely fine-grained and some of the high-grade material has a conspicuous thinly layered structure. The metallic minerals, in order of decreasing abundance, are pyrite, sphalerite, chalcopyrite, galena, and tennantite; the gangue minerals, in the same order, are dolomite and magnesite, quartz, sericite, talc, chlorite, barite, albite, and alunite.The geological setting of the deposit is shown in Figure 2. Except along streams and lake shores, almost all of the bedrock is concealed by glacial drift. The group of rocks in which the deposit occurs consists principally of greywacke, siltstone, tuff, brecoia, and Javas, and has been correlated lithologically with the Bourinot group of Middle Cambrian age. A short distance west of the mine, these rocks are in contact along the Stirling fault with conglomerate, arkosic sandstone, and quartzite belonging to the Middle River group of Silurian or Devonian (?) age, which elsewhere in the area overlies the Bourinot group unconformably. The large bodies of granitic rocks in the region, and the large lenticular masses of diorite and quartz diorite associated with them, have been assigned by Weeks (5, pp. 68-69) to the Devonian."

Jan 1, 1949

Filtration of pulps of varying densities is an essential operation in the hydro-metallurgical production of zinc. The use of filters naturally applies only to the &quot;wet&quot; plants, and in these varying types and sizes are in commission. At Risdon, the Moore suction filter is used for the heavier pulps, except in one instance, where a modification of the Butters-Cassell filter is installed.Filter presses are in general use, and of these, one is a washing unit; the plates, and frames are of cast iron or mild steel, except in one case which is a centre feed press having wooden frames.FILTER DESIGNThe problem of filtration presented itself very early in the history of Risdon and the first developments occurred in what was termed the 250 -lb. plant. Here experiments were made with many types of filters, and as this was the pilot plant on which the design of the 10 ton plant (10 tons of zinc per day) was based, quick decisions were necessary.An Oliver type filter was chosen for the heavier pulp or residue, and a Shriver wooden frame filter press for the lighter pulps.To this day, but with a number of variations, filter presses continue to function unopposed in their particular field; however, the Oliver filter was soon superseded because it was found impossible to wash the filter cake efficiently without repulping; consequently its use was abandoned and the Moore filter adopted.Both- these filters have been modified and developed in many ways to meet the requirements of a zinc plant, but they retain their original basic features.

Jan 1, 1949