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By E. G. Dean

A method of top slicing has been devised at the Miami Copper Co.'s mine at Miami, Aria., which differs radically in some ways from the customary methods of top slicing. The area of that section of the orebody in which top slicing is used is about 800 ft. square. The ore, while for the most part soft, is, nevertheless, considerably harder than the capping. The latter is siliceous, seldom containing any clay or other binding material, and breaks into fine particles so that it runs like sand if given the opportunity. Because of these facts, and because the ore is above the average grade of the mine ore, it has been mined by top slicing. Haulage levels are opened up 150 ft. apart, vertically, with two sub-levels between at 50-ft. intervals, to facilitate the putting up of ore chutes. These sublevels are used during slicing for distributing air in the ventilation system. On the haulage level the drifts are spaced on 50-ft. centers, and raises along these drifts are also spaced on 50-ft. centers, except the incline raises as hereafter noted. The raises are cribbed where necessary. Where the wear will be excessive, 1/4-in. iron plates are spiked to the top of every third set of cribbing, for its protection. When top slicing was first used, an attempt was made to carry a slicing face from fifty to several hundred feet long. Timber and other supplies were brought in through long drifts from an auxiliary shaft. Great difficulty was experienced in keeping these drifts open, the side pressure breaking the posts and the top weight breaking both caps and posts. Furthermore, the men could not work efficiently while these drifts were being repaired. The slicing faces advanced irregularly, due to varying conditions, and in many ways the results were not all that could be desired. It was then decided to divide the slicing area into blocks 200 ft. square and this was later changed to 250 ft. square. At the center of each block a two-compartment raise is put up as a supply raise, the compartments being 2 ft. 6 in. and 4 ft. by 4 ft. 4 in., the smaller being used as a manway. Station sets of 12 by 12 timber with

Jan 1, 1917

By L. D. Jaffe, John H. Hollomon

Fox many steel parts it is desired to obtain the maximum toughness consistent with the strength required by the mechanical design. It is generally recognized that the greatest toughness at any given strength is found in steels having a tempered martensitic structure,1 and is virtually independent of the composition of the steel2 (except for carbon). The choice of the composition of a steel for the parts in question should be based, therefore, on hardenability considerations and on manufacturing facility and economy. In a recent paper3 the concept of hardenability was discussed and a somewhat new approach to the problem was suggested. The hardenability was defined in terms of the cooling conditions (speed of cooling) required to avoid the pearlite and the bainite reactions. Since all the alloying elements do not have the same effects on the two reactions, the bainitic and pearlitic hardenabilities must be considered separately. In order to design a steel for a given part, it is necessary to design a composition that has both sufficient pearlitic and sufficient bainitic hardenability. However, this requirement does not fix the combination of alloying elements to be used; an infinite number of steels would have the required hardenabilities. Other considerations limit the choice. For example, decreasing the carbon content increases the toughness at a given hardness, and for this reason low-carbon steels are often desired. Limitations or requirements of refining, casting, or forming practices often affect the level of some of the alloying elements. Price considerations enter. Frequently, however, it is very desirable to minimize the tendency toward quench-cracking while maintaining the necessary hardenability. This paper is concerned with suggesting a method for choosing compositions that will have the required hardenability together with minimum tendency toward quench-cracking. QUENCH-CRACKING Since only the case in which the entire part will transform to martensite in the particular quench employed is being considered, the analysis of the quench-cracking problem is somewhat simplified. Quench-cracking arises from the temperature gradients existing throughout the piece during cooling. Because of these temperature gradients, the contraction arising from the decreasing temperature and the expansion arising from the austenite-martensite reaction do not occur uniformly over the parts, and stresses are set up that tend to cause cracking. The temperature gradients can be reduced by decreasing the severity of quench. This, however, requires that the hardenability be correspondingly increased by increasing the carbon or alloy content. An

Jan 1, 1946

By Paul D. Merica, W. A. Mudge

ONE of the most prominent features of our present-day industrial development is the ever-increasing demand put upon materials of construction Engineering ingenuity, within the past 25 years, has been unusually active, and in some fields at least engineers frankly say that engineering design has progressed as far as the limitations imposed by the properties of the present materials of construction will permit. Consequently, they are today demanding improvement in their working materials and seeking new ones, through the aid of which the present limitations of design may be overcome The activity of this search is evident in all fields, but it is particularly so in that of structural materials required to be resistant to corrosion The corrosion resistance of metals and alloys is never absolute and all-inclusive, a particular alloy will withstand some corrosive conditions well and fall utterly under others Furthermore, other properties, physical and mechanical, required in conjunction with corrosion resistance vary considerably for different commercial applications One wants a soft, ductile sheet metal resistant to atmospheric corrosion, another, a high-strength alloy resistant to sulfuric acid The last decade has witnessed active and definite progress in the development of high-strength, corrosion-resisting alloys In June, 1924, a symposium by the American Society for Testing Materials, on Corrosion-Resistant, Heat-resistant and Electrical-resistance Alloys, disclosed no less. than 60 commercial alloys the properties of which were described as being suitable for industrial service where corrosion resistance

Jan 1, 1935

By L. D. Jaffe

IN 1945-1946, the author measured temper brittle-ness in ingots of varying composition prepared by remelting SAE 3135 bar stock under vacuum. Since other investigators1-" have been referring to this hitherto unpublished work, belated publication seems worthwhile. Steel in 7 lb batches&apos; was induction melted with nickel additions in a magnesia crucible under a pressure of 10 microns of Hg or less and cast into a 2 in. diam chill mold. The compositions of ingots A, B, and C prepared in this way are shown in Table I; the vacuum melting lowered carbon, manganese, sulphur, and nitrogen content. Ingot B was homogenized 24 hr at 1095°C; ingots A and C were not homogenized. Blanks, M in. square, were cut from each ingot, austenitized 1 hr at 870°C, water quenched, tempered 1 hr at 595"C, and water quenched. Half the blanks from each ingot were given an embrittling treatment of 50 hr at 455°C and water quenched. A few specimens, embrittled and unembrittled, were finally heated 1 hr at 580°C and water quenched. Charpy specimens machined from the blanks were V-notched on the side closest to ingot mid-radius and paired as to radial position in the ingot, one of each pair having received the embrittling treatment and the other not. Specimens were broken in a standard impact machine at various temperatures, the same temperature, in general, being used for both bars of a pair. Fig. 1 shows the results. It is evident that temper brittleness, as measured by the increase in temperature of transition from brittle to tough failure introduced by the 455°C treatment, was decreased but not eliminated by reducing carbon to 0.006 pct, manganese to < 0.004 pct, and nitrogen to 0.001 pct. In another study," temper brittleness was apparently eliminated by -reducing carbon to 0.003 pct, with 0.80 pct Mn and 0.0015 pct N (ingot D)." • Analyses given for carbon below 0.02 pct were made by Jensen method; for nitrogen, by Kjehldahl method. Values quoted else-where&apos;-&apos;." for carbon content of ingot C and for nitrogen content of ingot D were obtained by conventional combustlon and by vacuum fusion methods, respectively, and are considered much less accurate. The 580°C final treatment removed previous em-brittlement (ingot B particularly), indicating that this was "reversible embrittlement."" Metallographic examination of ingot C with 1 pct nital etch revealed only ferrite; ingot A had carbide spheroids uniformly distributed in a ferrite matrix. With ethereal picric acid plus zephiran chloride etchant.&apos; no differences between embrittled and un- embrittled specimens of ingots A, B, or C were noted. Fracture of C and D below the transition temperature was predominantly transcrystalline, with traces of intercrystalline, in both embrittled and unembrittled conditions. The corresponding fracture of unembrittled B was mixed transcrystalline and intercrystalline; of embrittled B, predominantly intercrystalline with some transcrystalline areas. . . . Acknowledgment The efforts of J. C. Leschen, formerly of National Research CO~P., in preparing the ingots are acknowledged with thanks.

Jan 1, 1956

The U. S. Navy Department has perfected plans for the enrollment and training of considerable numbers of engineering officers. A school for this purpose, the U. S. Navy Steam Engineering School, has been established by the Department at Hoboken, N. J. The school is open to men between the ages of 21 and 40 who meet the physical requirements of the Navy, who are of thorough ability and officer-like character and who have completed the mechanical or electrical engineering course at certain recognized technical schools, or who possess an education and experience adjudged to be an equivalent thereof. Enrollment in the U. Naval Reserve Force of men properly qualified may be made at any Naval enrolling office, notation being made of the applicant&apos;s qualifications and desire to be detailed to this school. Applicants will be enrolled as Chief Machinist Mates, and during the course of instruction will draw the pay of this rating, $83 per month, plus $60 per month paid as subsistence. Upon graduation, men will be commissioned as Ensigns in the U. S. Naval Reserve, with a salary of $1700 per year. The duty to which a graduate of this school will be assigned will be that of an engineer officer in the auxiliary service of the Navy. Special provision has been made for the continuance of the school with proper material by a Navy regulation which permits undergraduates of the Freshman, Sophomore, and Junior Classes in recognized engineering schools to enroll in the Naval Reserve Force with the rating of Seaman 2d Class, and continue their courses at the institutions where they have matriculated. Such men will be called into active service after their graduation, and can at that time, if they are qualified to pass an officers&apos; physical examination, apply for admission to the U. S. Navy Steam Engineering School. Men who are registered in the draft, either graduates or undergraduates, may enroll with the proper enrolling officer by securing from their draft board a letter of release, which in all probability can be obtained for this purpose. The aim of this school is not simply to produce engineers, but to produce naval engineering officers in the true sense of the word. The course of instruction covers a period of five months, arranged in four periods.

Jan 10, 1918

By G. D. Rieck, G. H. G. Vaessen, D. L. Vogel

Both doped and undoped tungsten single crystals exhibit hardness anisotropy with respect to the direction of testing in each of the crystallographic phes investigated. The hardness anisotropy of undoped single-crystal tungsten is rather pronounced in (001) and (110) planes but very minor in (111) planes. The anisotropy in (122) planes of the doped and drawn tungsten after recrystallization is in accordance with a previously published concept of a stringlike distribution of the doping material in the metal. ANISOTROPY in mechanical properties of single-crystal tungsten was investigated by Rose et al., Garlick and Probst,2 and Beardmore and Hull. 3 Although data on the Vickers microhardness of tungsten have been published (see, e.g., Boosz 4 and the references cited by him), no data on the microhardness anisotropy are available. We report, therefore, some of our own results on the microhardness and its anisotropy. The microhardness has been determined of the following samples. A) Polycrystalline tungsten samples taken from: 1) powder metallurgical tungsten "normally" doped with potassium-silicon-aluminum oxides (final contents inppm: K, 100; Si, 100; Al, 20; Cr, 20; Fe, 50; Mo, 400; Ni, 10) and in the form of: a) a 10-mm-diam swaged ingot annealed at 1600°C, the grain sizes varying between 15 and 250 p; b) a sheet rolled at about 800°C and recrystallized at 2000°C7 the grain sizes varying between 15 and 150 p; c) a 2-mm-diam swaged rod, as-worked, with elongated grains (average diameter of about 25 , lengths up to 1 mm); 2) undoped electron-beam-melted tungsten with very large grains (contaminations in ppm: K < 10; Fe < 20; Cr < 10; Cu < 0.1; Ni not detectable; inter-stitial~ not determined). B) Single-crystal samples taken from: 1) pure tungsten grown on a Pintsch wire by the van Arkel procedure (main contaminations inppm: Mo, 100; Si < 10; Cu and Fe, 2; A1 < 2; interstitials not determined); 2) zone-melted undoped tungsten (analysis as under A2); 3) large crystals in secondary recrystallized tungsten

Jan 1, 1969

By Frederick Beckett

WIDESPREAD experimentation has been conducted in recent years to devise a means of preventing intergranular corrosion in austenitic chromium-nickel steels of the 18 per cent chromium-8 per cent nickel type. Additions of titanium to these steels have been used commercially to overcome this difficulty, as advocated by Krupp of Germany, and the latest literature reference concerning improved details of this method is the article by Bain, Aborn and Rutherford.1 Extensive work by the present authors has shown columbium also to be a particularly valuable agent for inhibiting intergranular corrosion. This paper does not deal with steels that are largely or wholly aus-tenitic ; it is limited to a discussion of the results obtained through the use of titanium and columbium in plain high-chromium steels. For many years titanium has been used commercially by some steelmakers as a cleanser, and to a lesser extent as a hardener, but then in greater per-centages. The results of the work to be described disclose that titanium and columbium in proper proportions act as effective softeners in the high-chromium steels. It is well known that chromium intensifies the hardening effect of carbon in steel; it imparts pronounced air-hardening properties within a rather wide range of chromium content; it provides increased ductility in steels of given strength and hardness; and it enhances resistance to corrosion and oxidation at elevated temperatures to a marked degree. However, in applications requiring a combination of some of these valu-able properties great hardness is frequently a detriment rather than a merit. When the objective is a soft and ductile steel having optimum corrosion resistance, the producer strives for a carbon content as low as commercially practicable.

Jan 1, 1933

By J. E. Tobey

UNQUESTIONABLY, manufactured gas will stage a comeback of such huge proportions as to dwarf its previous history. Timing will depend on two things: the diminishing supply of natural gas and the perfecting of processes for large-scale production of high-Btu gas from, coal. What the timing will be, and how soon the new era will begin for manufactured gas, no one knows. It may be just around the corner and it may be several years, but it is certain to come. It will depend on economic changes, and any major world upheaval might accelerate it tremendously. Supplemental gas for pipelines will come no doubt from two sources at least: (1) synthetic-fuel plants of the coal-chemical group, which produce chemicals and liquid fuels with a tail gas high in methane as a by-product; and (2) large-scale gasification plants, which will produce high-Btu gas entirely or as a major product with chemicals and liquid fuels as by-products. There is important activity at the present time, in the development of new processes and the improvement of those now in existence. The first large-scale gasification plants of the second category probably will be strategically located in the coal fields on or near the long-distance transmission gas lines, and these plants probably will operate jointly with large natural gas storage fields. Inasmuch as virtually all the major gas-transmission lines cross one or more coal fields, such locations will not be difficult to find. It will be a practical necessity to produce a high-Btu gas -that is, 750 to 1000 Btu-in order to maintain the capacity of the main transmission lines and local city distribution systems and further to eliminate the problem of appliance changeovers in the cities. If gasification plants on a medium or smaller scale prove to be economical, local gas utilities no doubt will consider .the construction of such plants to supplement their supply of natural gas. If low-temperature distillation processes like those now being developed by the Pittsburgh Consolidation Coal Co. are successful, and there is reason to believe that they will be, utilities that supply both gas and electricity to communities would find this method particularly attractive, as they could burn the char product directly under power boilers, thereby minimizing thermal

Jan 1, 1953

By W. D. Keller

THE high-alumina clays of Missouri are interesting for several reasons. They are the only sedimentary deposits in North America of first grade (over 70 pct A1,0,) diaspore and boehmite sufficiently large to be mined commercially. Mineralogically, they are composed of diaspore and boehmite in intimate coexistence, but gibbsite, the common hydrated alumina mineral in bauxite and laterite, is absent, or is exceedingly scanty if present.* Therefore, the Missouri high-alumina clays do not represent typical laterization. The physical chemistry leading to their mineral genesis, and the geolbgical setting for their formation, present important problems for scientific study. The origin of the Missouri high-alumina clays has been discussed in earlier reports by Allen1 (1935) and McQueen 8, 9 (1929, 1943). These investigations were made under difficult conditions, however, because no diaspore deposit had been opened where a Paleozoic (Pennsylvanian) rock cover lay undisturbed over the high-alumina clay. The relationship of the clay to only the underlying rocks could actually be observed. Lacking the guidance of critical postdepositional geologic evidence, undue and erroneous emphasis was placed on the postdepositional leaching of the deposits in the theories on the origin of diaspore and boehmite from clay (hydrous aluminosilicates) . With new geologic evidence at hand, a clearer picture can be made for the origin of the Missouri high-alumina deposits. In this paper the geology of a diaspore deposit whose original Paleozoic cover had not been eroded will be described and interpreted genetically. The close relationship of boehmite and diaspore (also with kaolinite and a chloritic mineral), will be established. A theory of origin for the high-alumina clays, consistent with the new data, will be postulated.

Jan 1, 1952

By F. X. Tartaron

The comparison of actual energy of comminution with theoretical surface energy presents a wide gap. On the other hand, Solid State Theory presents a viewpoint that places actual energy of breakage in understandable relationship with the theoretical strength of materials. Therefore the physical background of comminution theory favors Kick&apos;s Law. A11 discussions of comminution theory appear farfetched when comparison is made of the actual energy of crushing with the energy input called for by thermodynamic theory. Quoting Taggart:&apos; "The work required to crush halite was of the general order of 0.10 kg cm per sq cm of new surface produced (based on air percolation) whereas the theoretical energy of this new surface, based on thermodynamic calculation by a number of investigators is 1 x 10&apos;4 kg cm per sq cm or the work expended was 1000 times the new surface energy — an indicated crushing efficiency of 0.10 pct." It is frustrating to probe into comminution theory with the prospect that the energy one is measuring is 99.9 pct waste energy. Do the laws of comminution deal with energy consumed by mineral breakage or with waste heat energy? There seems to be something wrong. Solid State Theory may provide the answer. The following statement is particularly apt to the situation: "The fundamental fact about metals and indeed all materials, is that they are much weaker than they should be. By this, we mean that if the stress required to cause a given plane of atoms to slip past a neighboring plane is calculated from basic atomic and Solid State Theory, the resulting number is some 1000 times too large to be accounted for by errors in approximations or assumptions. We know now that this is due to dislocations, and we even have a fair understanding of the details of the process by which dislocations make a crystal weak. An intriguing possibility which suggests itself, results from the discovery of very minute metallic crystals which are apparently free of dislocations and which have a strength approaching the ideal value for a perfect crystal." Here we have an extraordinary reversal of the situation. The actual energy for breakage is only one-thousandth the theoretical instead of 1000 times as given by Taggart. But the theoretical energy presented by Solid State Theory is the binding energy between atoms (or ions) in a crystal lattice. This is the kind of energy envisaged by Kick&apos;s law. The surface energy or the other hand corresponds to Rittinger&apos;s law. Comparison of theoretical with actual, on the basis of surface or on the basis of Rittinger&apos;s law, seems to present an absurdity; yet Rittinger&apos;s law is confirmed by an impressive array of experimental evidence. Comparison of theoretical and actual on the basis of Solid State Theory or, in other words, on the basis of Kick&apos;s law seems reasonable; yet there is not a scrap of evidence to verify Kick&apos;s law. The situation appears paradoxical, but the developments in the next section of this paper show that the paradox is a hint to a strange turn of events. ENERGY-WEIGHT FRACTION FUNCTION charles3 has presented a final equation showing the relation of energy consumed in comminution to size of product n{-1) a-n + 1 E is energy, C is proportionality constant, a and n are constants and k is the coarsest size in the ground product (size modulus). In the course of study of a large amount of experimental evidence, Charles discovered that in the general case, a-n + 1 approximated zero. For some reason, a and n differed only by unity. But if a—n + 1 = 0 within experimental error, then it is obvious that Eq. 1 states that it requires an infinite amount of energy to grind any sample to any size. This is a case where nature gives an absurd answer to a man-made mathematical equation, hence something is wrong with the equation. An adjustment must be made to fit the equation with experience. TO reveal the nature of the adjustment, the differential equation preceding the second integration in Charles&apos; group of equations is given When Charles integrated the quantity xa-n it was almost impossible for him to realize that he was dealing with a special case of integration and that

Jan 1, 1962

By H. J. Struth

Economic law was accorded considerably more recognition by the oil industry last year than perhaps ever before. While proration was undoubtedly given added impetus in 1931, and the list of proponents of unit operation was noticeably lengthened, predominant evidence plainly shows that the functioning of economic laws dominated collective efforts to reduce the excessive above-ground supply of petroleum. Crude oil production was reduced more than 48,000,000 bbl. last year; imports from other parts of the world were substantially lower; stocks of crude were drawn upon to the extent of nearly 48,000,000 bbl.; domestic gasoline demand increased 2 per cent—and yet, prices of petroleum and its products were at the lowest levels in many years. To say that the ills of the oil industry during 1931 were due to the general depression that was felt in all other lines is tantamount to attaching an air of uncertainty to a group of commodities that have been proved to be an ever increasing necessity, even in times of depression. TO say that the potential productivity of proven oil-producing areas has been responsible for the unsatisfactory state of affairs last year, and now, is to admit failure to carry out the principles designed to control production in accordance with the limits prescribed by demand. In fact, there is no reason why a large proven potential supply of oil should not be considered a valuable asset to the industry; an assurance against future needs; a stabilizing influence in building up confidence in the ability of the industry to supply this and future generations with fuel and lubricant requirements at reasonable prices. At any rate, an assured future supply of oil should be interpreted to the public to mean that the oil industry is a legitimate, progressive industry, and not a group of prospectors madly searching for "liquid gold." There has been a great deal of romance connected with the history of the oil business—so much that the public has come to associate the word "oil" with untold riches. However, the financial statements of 1931 will furnish conclusive proof to the contrary. Too much oil, too many refineries, too many filling stations, too much capital invested; these and other "too muches" and "too manys" have perhaps been given more publicity than necessary. We seldom hear these

Jan 1, 1932

By Robert Archer

THE proper material of construction for a given purpose is that material which meets the requirements satisfactorily at the lowest ultimate cost. It is consistent with this principle that most aluminum castings are made of an alloy containing about 8 per cent. copper. This alloy possesses mechanical properties satisfactory for general engineering purposes together with manufacturing characteristics leading to the production of finished castings at low cost. It is to the aluminum industry what gray iron is to the iron and steel industry. Just as some services require "semi-steel," malleable castings or steel castings instead of gray iron, there is a certain and growing demand for aluminum castings of superior strength or ductility, or both. Since the beginning of the industry producers and others have sought to develop alloys or processes by which such castings could be made. Out of these efforts have emerged many alloy compositions and special processes, of which only a few have had sufficient merit to survive. It is the purpose of this paper to describe those which seem to the authors to offer the greatest promise for the production on a commercial scale of aluminum castings of superior mechanical properties, with special reference to heat-treated castings. The suitability of an alloy or process for actual manufacture is affected by so many factors that the problem of appraisal is not a simple one. Since this is such an important part of the whole subject it is proposed to discuss briefly some of the requirements. The final verdict is of course the result of commercial trial and experience. It will therefore, perhaps, be profitable to employ a somewhat historical method of treatment in discussing the subject of alloy development.

Jan 9, 1926

By L. Segle, R. Resnick

NUMEROUS experiments in the past few years have proven that void formation occurs quite generally in the diffusion zone of bimetal specimens1-4 The phenomenon has been explained in terms of the accumulation of lattice vacancies resulting from unequal diffusion of the constituents and their eventual precipitation as holes.= Attention has recently been directed to the fact that voids also form within homogeneous metals during high-temperature creep.&apos; The idea has been put forward that these voids form by the condensation of excess lattice vacancies generated by intersecting dislocations.".&apos; If the precipitation of lattice vacancies from solution is treated as a nucleation and growth process, the predicted vacancy concentration for homogeneous nucleation of voids at an observable rate is 100 to 1000 times the normal thermal equilibrium concentration. It appears that voids actually form during diffusion at vacancy supersaturations which are much lower than this8 According to the calculations of Machlin,&apos; the same must be true for voids formed in homogeneous metals during creep, if these are considered to arise from the precipitation of lattice vacancies. Therefore, if the vacancy mechanism is valid, it seems that the holes which form in diffusion and creep specimens are heterogeneously nucleated by imperfections or impurities in the metal. Irregularities in the frequency and distribution of voids in diffusion couples bear out this explanation.&apos; , It is not known at the present time what the nuclei are on which vacancies condense. Various investigators have speculated that they could be certain dislocation configurations, already existing voids produced during solidification or working, gas pockets, or inclusions in the metal. Relatedly, the precise value of the degree of vacancy supersatura-tion for void nucleation is still uncertain. An initial attempt to estimate this value from diffusion data, made by Balluffi, indicated that voids form in diffusion couples at vacancy concentrations which may

Jan 1, 1958

By T. O. King, Y. P. Gupta

The self-diffusion of sodium in two sodium silicate liquids was measured in the temperature range 850" to 1500°C by the capillary-reservoir technique. Radioactive Na 22 was used as the tracer. The total count and autoradiographic methods were used for determination of the total Na 22 depletion and diffusion profiles of the dqy-used specimens. The diffusion coefficients obtained by the autoradiographic technique are slightly smaller than those obtained by a total count method. Error analysis of the two methods suggests that more confidence be placed in the results of the total count method. The experimental results were analyzed in terms of the existing activated rate process theory. The activation energy for diffusion was shown to decrease markedly as the temperature increased. This was attributed to a variation in the heat of activation with temperature, probably related to a change in the distribution of anions associated wilh the cation. In terms of a model, suggested for diffusion in liquid silicates, differences in the aclivation energies for diffusion and electrical conduction may arise from the effect of the electric field applied in conduction measurements. It is generally accepted that liquid silicates consist of cations and an equilibrium distribution of complex anions determined by temperature and composition. Transport properties in molten silicates are of interest, not merely because of their relevance to the kinetics of pyrometallurgical reactions and glassmak-ing processes, but also because they are useful to development of the theory of such ionic liquids. Self-diffusion is one such transport process that may, if studied for liquid silicates of widely varying compositions, indicate structural changes through changes in the activation energy for diffusion. The self-diffusion of calcium, silicon,&apos; sulfur: aluminum, 4 and oxygenS in lime-alumina-silica melts and of iron6 in molten iron silicates have been measured. Unfortunately, the errors in some of the reported activation energies for diffusion are too large to allow firm conclusions concerning structure and the mechanism of the diffusion process to be drawn. The research reported here was a study of the self-diffusion of sodium in liquid sodium silicates. The soda-silica system was chosen since: i) a reasonable composition range can be covered in the binary system at moderate temperatures; ii) suitable isotopes of sodium (radioactive Na 22 and NaZ4) can be obtained; iii) data on the electrical conductivity and viscosity of sodium silicate liquids are available. However, the range of composition actually used in diffusion experiments was limited, to 20 to 35 wt pct soda, by the relatively high viscosity of silica-rich compositions and by evaporation of soda from basic melts. EXPERIMENTAL PROCEDURE The capillary-reservoir technique was used, wherein a radioactive tracer, Na 22, incorporated in the capillary melt, was allowed to diffuse out of the platinum capillary tube into a large reservoir of silicate liquid containing a chemically identical melt, but without radioactive tracer. After a specific diffusion time, both the total depletion in the tracer concentration and concentration-distance profiles of the diffused samples were measured by procedures to be described later. The diffusion cell assembly was similar to that used by Koros and King.&apos; The temperature of the diffusion cell was measured with a calibrated Pt, Pt-10 pct Rh thermocouple located at the center of the liquid reservoir. The same thermocouple was used to obtain the temperature profile in the reservoir. The temperature at the top of the reservoir was slightly higher (2°C) than that at the bottom, to minimize convection in the capillary tubes, which were placed, open end up, in the reservoir. Convection was not expected to be a problem since the length-to-diameter ratio of the tubes was about 12:1 and the maximum capillary diameter was 1 mm. The diffusion cell was heated in a molybdenum-wire resistance furnace, previously used by Koros and King, but somewhat modified. A Pt, Pt-10 pct Rh thermocouple enclosed in an alumina tube and located near the furnace winding was used in conjunction with a preamplifier and Micromax proportional controller for temperature control, within 4°C, at temperatures near 1500°C. Before starting a diffusion run, the furnace was heated to the desired temperature and an alumina guide assembly for the capillaries was slowly lowered to within 2 cm of the liquid reservoir. The capillaries were thus heated to about the temperature of the bath. The run was started by lowering the assembly till the open ends of the capillaries were about 1 cm below the surface of the liquid. The run was ended by raising the assembly to about 15 cm above the liquid bath. Later, the sample assembly was slowly withdrawn from the furnace. Six diffusion samples were usually run at the same time. Three runs made with the open ends of the capillaries down were discarded because in the majority of these samples air bubbles trapped at the open end were observed. Some glass adhered to the outside of the capillary on withdrawal. This was carefully removed and used to check that the Na 22 activity in the sink remained at a low level. Materials. Nonradioactive sodium silicates were prepared by melting, in a platinum crucible, weighed quantities of sodium carbonate and powdered silica. To prepare radioactive sodium silicates, Na2 obtained in HC1 solution, was first checked for radioactive impurities by obtaining a y-ray energy spectrum, then the chloride ions were removed by anion-ex-

Jan 1, 1968

By Edmund Newton

The steel industry of the United States has depended in the past almost wholly upon imports for its supplies of manganese. Many of the important domestic sources yield ores leaner in their natural condition than the foreign ores the steel industry. has been accustomed to use. To make them available, therefore, either the ores must be concentrated or the practice of the steel industry modified. Roughly 25,000 T. annually of high-grade manganese ores are used for dry batteries for chemical purpose, and in other ways; while approximately 750,000 T. are required for making steel. , By present practice, every ton of steel takes an average of about 14 lb. (1.8 kg.) of metallic manganese. This is generally added to the steel in the form of an alloy, the standard alloys being the 80-per cent. ferro-manganese and the 20-per cent. spiegeleisen, During the year 1917, 286,000 T. of ferromanganese and 193,291 T. of spiegeleisen were made in this country, the former largely from imported ores; and 45,381 T. of ferromanganese. was imported. The metallic manganese represented by these alloys was 304,000 T., the product of roughly 800,000 T. of high-grade ore and 345,000 T. of low-grade ore. Manganese Deposits in the United States Before the war manganese ore was mined in relatively small quantities in the Appalachian region, including Virginia, Tennessee and Georgia, and in Arkansas, but owing to the increase in prices during the past three years manganese mining has been undertaken also in Montana, California, Arizona, New Mexico, Nevada, Utah, and Minnesota. From data now available it appears that in this country deposits of high-grade manganese ores are usually small, while materials lower in manganese and higher in iron occur in appreciable quantities. Our total quantity of manganese-bearing material is relatively large, but on

Jan 1, 1920

By A. L. Benham, W. E. Dowden, W. J. Kunzman

The mechanism involved in creating a miscible fluid displacement of typical reservoir fluids through porous media by light hydrocarbon mixtures usually involves a number of mixing and separation stages in the contact area. This mechanism has been illustrated on ternary diagrams for miscible displacement of reservoir fluid by rich hydrocarbon gases. A relatively simple method has been devised for calculating the approximate conditions for a miscible displacement of reservoir fluid by rich, light hydrocarbon gases or by LPG mixtures. Miscibility is favored by increased pressures, decreased temperatures, light reservoir fluids and light hydrocarbon-displacing fluids rich in the heavier components. The conditions for miscible displacements of five typical reservoir fluids by various light hydrocarbon mixtures were determined for a range of temperatures from 70" to 260°F and pressures from 1,000 to 3,000 psia. A correlation of these conditions was obtained using the variables of temperature, pressure, C,+ molecular weight of the reservoir fluid, C,+ molecular weight of the displacing fluid, and mol per cent methane in the displacing fluid. This correlation has been applied to data appearing in the literature with very good success. A partial check of the correlation has been made using a step-wise procedure with a windowed PVT cell. INTRODUCTION The term, "miscible fluid displacement", may be defined as any oil-recovery displacement process where there is an absence of a phase boundary or interface between the displaced and displacing fluids. A water flood would not be a miscible fluid displacement, although cycling in a condensate reservoir would be. Another example is displacement of oil by gasoline. Not so obvious, however, are the conditions under which fluids (such as propane, mixtures of propane and methane, or other similar systems) will give a miscible fluid displacement of oil. There are four standard miscible-fluid-displacement processes being used for the recovery of oil from an "nderground reservoir—(1) high-pressure dry-gas miscible displacement, (2) rich-gas miscible displacement, (3) miscible slug using a slug of LPG followed by a lean dry gas under miscible conditions, and (4) gas driven-slug process using a slug of LPG followed by a lean dry gas under immiscible conditions. The first problem faced by the engineer designing a miscible displacement process is to determine the conditions for miscibility. A number of papers have included discussions of the process of obtaining miscibility in these processes.1-8 However, methods for calculating the conditions for miscibility have not been published. This paper includes a method for calculating the conditions for a miscible displacement of reservoir fluid by a rich gas (LPG diluted with methane or natural gas). In this paper, a rich-gas miscible displacement process is defined as an oil-recovery process in the reservoir. The cost of a rich-gas miscible displacement will be decreased by diluting the LPG with methane or natural gas as much as possible. Therefore, it is important to be able to predict the maximum dilution for miscibility. MECHANISMS The mechanisms for obtaining miscibility between a displacing mixture of light hydrocarbons and displaced reservoir fluid often involve a number of displacing and mixing stages. As stated previously, the cost of a rich-gas miscible displacement is decreased by diluting available LPG with natural gas. The problem is to predict the maximum dilution allowed while maintaining miscibility. To get a picture of the displacing and mixing stages, it is helpful to consider these complex hydrocarbon mixtures as pseu do-ternary systems. Graphical representation of a complex system as a pseu do-ternary system can be thermodynamically rigorous if enough variables are used to describe the character of each pseudo-component in one of the phases. However, even if the characterization of each pseudo-component is not complete, pseudo-ternary representation does serve to illustrate the mechanism for obtaining miscibility and can be used to make some general conclusions concerning the conditions for obtaining miscibility. A phase diagram for the ternary system, methane-

By H. N. Kalia, J. B. Gresham

Several attempts have been made in the past 60 years to commercialize the vast oil shale deposits of the US. However, the industry has yet to become economically viable. To date, it has not been possible to produce oil from oil shales at a competitive price compared with oil produced by conventional methods. The development work, nevertheless, has been fruitful in furthering the art of thick bed mining and technology of in situ retorting. The in situ method has the potential of recovering oil from thick beds, and the resource recovery potential is much greater than that from underground mining and surface retorting. In situ methods require that the shales/marlstones be fragmented in place to induce adequate porosity and permeability to allow in situ heating of the fragmented shales. This can be accomplished by using explosives. However, it has been found that the existing blasting systems, though very efficient, have some drawbacks. The explosives become insensitive when shot in multiplevertical decks. They can also become insensitive when spaced horizontally at close proximity to other charges. Also, since the blasting is done in a very limited free face, the delay time that can be allowed between charges is also quite limited. Consequently, it is not always possible to routinely predict the performance of the blasting system. Furthermore, since it is not possible to undertake secondary blasting, it is imperative that the blast design function properly. Recent successful retorting by Occidental Petroleum Co. Of Retorts 7 and 8 suggests that some of these problems may have been overcome. This paper addresses some aspects of in situ retorting and problems that have impeded the development of a viable oil shale industry in the US.

Jan 1, 1986

By Carl Scholz

During November and December, 1907, four serious mine-explosions occurred in the Appalachian coal-field, which resulted in the loss of nearly a thousand lives and caused an eliormous damage to propcrty. These accidents attracted more than the usual attention; coal-trade and engineering papers contained many comments and suggestions on the cause and prevention of accidents; the daily press in many instances condemned the coal-operators and charged these accidents to their negligence, or their anxiety to make money without adopting precautionary measures. Immediately after cach accident the respective State authorities ordered close investigations to be made, with the view of establishing the cause and suggesting remedies to prevent recurrence. Representatives of the Technologic Branch of the IT. S. Geological Survey, to whom the investigation of mine-accidents had recently been delegated by the Secretary of the Interior, visited the mines and co-operated with the local authorities in their determinations. It may be safe to say here that an investigation of a mine after an explosion has occurred discloses but little, because the causes hare been removed and conditions have been entirely changed. On Jan. 8, 1908, the coal-operators of West Virginia organized an association at qTashington for the purpose of making extensive investigations, and sufficient funds were pledged to carry out this work. At this organization meeting, the representatives of the Geological Survey present had no suggestions to offer as to the cause of these accidents. An examinatiou of the various reports concerning these accidents indicates that the explosions were caused by the ignition of gas or dust; they show the point of origin and the direction in which the force was expended, and give a detailed description of the damage done. Very little has bee11 said as to what

Jan 1, 1909

By F. G. Loper

Simulation as a mathematical technique is not new. However, recent increases in digital computer speeds and the ease of programming with languages such as Fortran have centered a good deal of attention around simulation in the last few years. By ignoring all but the relevant characteristics of a process, a mathematical simulator may be constructed which, when fed operating data, should react as the process would. The output becomes numbers, instead of tons, however. Thus, a trial-and-error operation of such a simulator will permit management to study a major system change at little cost.

Jan 1, 1967

By T. F. Petty

Oil and gas production in North Central Texas has been found in sands and limestones in the Cisco, Canyon, Strawn and Bend series of Pennsylvanian age and in lime of pre-Pennsylvanian age. Production ranges in depth below the surface from 150 to 4500 ft.; a few wells have been drilled to depths in excess of 5500 ft. and penetrated rocks of pre-Cambrian age. In Table 1, the average depth of the pools is shown. No mention, however, is made in this table of approximately 30,000 bbl. of oil produced in Callahan County from a pre-Pennsylvanian pay, presumably the Ellenberger, and an excess of 1,000,000 bbl. of oil produced from limestone, which has been identified as Silurian in the south part of Young County. This well is being produced at the present time. In Table 1 a great many pools of minor importance are listed, which are merely productive spots, and throughout the various producing counties there are numerous similar spots, which might be listed as pools. Their production, however, is listed in the county totals. In Table 2, the totals of the oil wells, gas wells, and dry holes drilled before Jan. 1,1935, include only wells on which records are available to the writer. In Brown, Callahan and Shackelford counties 2924 very shallow wells (150 to 600 ft. deep) have been drilled, on which the record is not available. Possibly there are other wells that were drilled before the district was adequately scouted. No classification as to the depths of this total of 30,644 wells is available at present. Initially, nearly all the oil wells of North Central Texas produced gas, and several areas producing dry gas have been partly developed. A number of casinghead gasoline plants strip the gasoline from the gas produced with the oil, and the manufacture of carbon black is an important industry in Stephens County. Dry and residue gas are marketed through systems serving the various towns of the district, San Angelo to the southwest and the cities of Forth Worth and Dallas to the east. Considerable gas is used in repressuring several pools, the most important of which are the Stover of Brown County and the Cook of Shackelford County. During the past year, 32 gas wells were completed, adding a

Jan 1, 1935