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By A. B. Young

IT is the he object of this paper to describe a Cottrell treater that was placed in operation, in April, 1919, at the Tooele plant of the International Smelting Co., for the purpose of recovering solids from the gases from the McDougall roasting furnaces. Fundamentally, the treater is simply a flue containing rows of vertical plates, forming the grounded electrode, alternated with rows of small horizontal pipes, forming the negative electrode, with proper provision underneath for taking away collected dust. There are advantages in construction over the more cumbersome types, both the vertical-tube and the vertical-box, particularly in the elimination of heavy supporting columns and massive foundations, giving a much lower first cost. There are no right-angle turns to interfere with gas distribution; consequently there is greater efficiency, or, in other words, a greater volume of gas per minute can be effectively treated. Another advantage of the horizontal installation over the vertical is that the principle of the selective precipitation of the various components of the dust and fume as they pass along the electric field may be utilized. Since the treater has been placed in operation, the results have been quite satisfactory and, in many ways, particularly in regard to the volume of gas that may be treated, have greatly exceeded expectations.

Jan 8, 1920

By Louis V. Bender

THIS paper gives a short review of the installation for and the use of gas, as a. fuel, at the Anaconda Reduction Works of the Anaconda Copper Mining Co. Before putting in gas tile fuels used were pulverized coal, lump coal, coke distillate and oil. These fuels are now almost entirely eliminated. For nearly fifty years bituminous coals from Wyoming and Montana fields had been used. These coals were of a good grade, analyzing 11,300 B.t.u. and having an ash content of 12 per cent. When hydro-electric power replaced steam-driven equipment, the coal requirements were reduced; and, on account of improvements in metallurgy and/ or in furnace design, the quantity was lessened. Later, oil and distillate were introduced and used in some of the operations. All of these things tended toward the lessening of the amount of coal used, and had it not been for the increase in the size of the plant, the tonnage used would have been small when the change was made to gas.

Jan 1, 1932

By Stuart H. Ingram

The term lightweight aggregate implies material which may be substituted for the usual rock, sand and gravel commonly used as the major part of concrete, but distinguished by being much lighter in weight. Background The art of making and using concrete is old and well developed. Research and experience have pretty well determined the qualities necessary in its constituents, and time has tested theories and applications. Elaborate specifications and tests have been devised and generally adopted governing all phases of concrete work, from selection of material, through engineering design and down to mixing and placing. Standard practices have become routine to executives and laborers, and operations have been simplified and costs lowered. Though many lightweight aggregates meet the basic specifications necessary for usefulness, their physical qualities are so different that they fiequently will not pass standard tests, and some of them cannot be mixed and placed with the usual formulas for water and slump. As a rule their use produces a concrete with a lower modulus of elasticity which requires design change, and being produced in much smaller quantities than ordinary aggregate, production costs are higher. This latter works in a vicious circle to restrict their use and maintain prices that are not competitive, except as against each other. Increased Demand In spite of such handicaps consumption has grown steadily for the past two decades and is apparently growing even faster today. It is evident that lightweight concrete must have better qualities, and be sufficiently better to Overcome the higher cost and the other difficulties and disadvantages pertinent to the use of a new and different material in an old industry. Hence the study of its main ingredient should be of interest to all engineers. Our group has a double interest in the subject since most of the materials which have been used as sources of lightweight aggregate are either mined, Or are by-products of mining operations. We are directly interested in their production as well as their use, and since available supplies of materials suitable are limited, the increasing use, and rising demand, make the discovery of new Or or the development of processes to adapt other natural materials to this use, a promising field; and one in which our profession should take an active part. Recent Development Descriptions of ancient work contain references to the use of spalls of tuffs Or pumice in concrete masonry, but it is only since the nineteen twenties that serious attempts have been made to produce and market lightweight aggregates. A period of rapid advance in theory and practice in cements, mortars and con-

Jan 1, 1948

By Stuart H. Ingram

The term lightweight aggregate implies material which may be substituted for the usual rock, sand and gravel commonly used as the major part of concrete, but distinguished by being much lighter in weight. Background The art of making and using concrete is old and well developed. Research and experience have pretty well determined the qualities necessary in its constituents, and time has tested theories and applications. Elaborate specifications and tests have been devised and generally adopted governing all phases of concrete work, from selection of material, through engineering design and down to mixing and placing. Standard practices have become routine to executives and laborers, and operations have been simplified and costs lowered. Though many lightweight aggregates meet the basic specifications necessary for usefulness, their physical qualities are so different that they fiequently will not pass standard tests, and some of them cannot be mixed and placed with the usual formulas for water and slump. As a rule their use produces a concrete with a lower modulus of elasticity which requires design change, and being produced in much smaller quantities than ordinary aggregate, production costs are higher. This latter works in a vicious circle to restrict their use and maintain prices that are not competitive, except as against each other. Increased Demand In spite of such handicaps consumption has grown steadily for the past two decades and is apparently growing even faster today. It is evident that lightweight concrete must have better qualities, and be sufficiently better to Overcome the higher cost and the other difficulties and disadvantages pertinent to the use of a new and different material in an old industry. Hence the study of its main ingredient should be of interest to all engineers. Our group has a double interest in the subject since most of the materials which have been used as sources of lightweight aggregate are either mined, Or are by-products of mining operations. We are directly interested in their production as well as their use, and since available supplies of materials suitable are limited, the increasing use, and rising demand, make the discovery of new Or or the development of processes to adapt other natural materials to this use, a promising field; and one in which our profession should take an active part. Recent Development Descriptions of ancient work contain references to the use of spalls of tuffs Or pumice in concrete masonry, but it is only since the nineteen twenties that serious attempts have been made to produce and market lightweight aggregates. A period of rapid advance in theory and practice in cements, mortars and con-

Jan 1, 1948

By H. Landsberg

SUBSIDENCE caused by mining operations has been a matter of interest for the mining engineer for just 111 years, since the Belgian Committee for study of subsidence in the city of Liege submitted its first report in 1825. This interest is fairly expressed in the enormous amount of literature that has since appeared on this subject. A bibliography, probably far from being complete, which preceded this study as a pre-liminary survey, comprises more than 800 titles. In spite of this fact the problem remains today as acute as it has ever been. The questions of as good a recovery as possible of the national resources, the safety of the operations, and the protection of private and public property are the important angles from which to look at the problem.

Jan 1, 1936

By C. D. Rugen

GROUND raw material as fed to the cement kiln generally is a mixture of two to four components, each of which may have widely varying physical and grindability characteristics. Chemically similar materials found in the same or different deposits may also differ appreciably in physical properties, depending on their crystalline structure. The calcareous or principal cement raw material may vary from a soft chalky limestone or friable cement rock at one plant to a hard limestone or oyster shell at another plant. Argillaceous materials include clays, shales and granulated slag. Siliceous and/or iron-bearing material, including sand, iron ore and cinders, may also be required in addition for certain types of mixes. Frequently differences in grindability characteristics are not given the attention they deserve in comparing grinding results at one plant with those at another or in selecting suitable circuits or equipment. Many types of crushing and grinding units are used, with numerous open and closed circuit arrangements. Both wet and dry processes are used successfully. When rebuilding or installing a new grinding department, the choice of process or circuit in some cases may be dictated by the nature of the materials being ground but in other cases it may be the result of good salesmanship or a compromise. An over-all evaluation of wet process vs. dry process grinding should not be made without considering the effects on all other producing departments in the plant. In general, the more recent grinding installations, both wet and dry, have employed closed circuits, but many older open circuits are still in successful operation. In our experience, closed-circuit raw grinding pays, because of lower power consumption and less operating labor per ton of product. However, some dry open-circuit mills with improved equipment and operating methods compare favorably in performance with dry closed-circuit units. CHARACTER OF GROUND RAW MIX (KILN FEED) Grinding in the cement plant in general requires a considerably finer product than in most ore-grinding operations. A distinction between fineness of kiln feed and of cement may be made in that kiln feed preferably should be ground to a limiting size, whereas finished cement should include a range of size fractions including sufficient fine flours to give a product with satisfactory physical qualities. Grinding raw mix for kiln feed therefore is more comparable to ore grinding, although the limiting size is smaller. Most kiln feeds are ground from 85 to 95 per cent passing 200-mesh, depending on mix composition. Some cement chemists believe that raw materials cannot be too fine, since finer particles theoretically combine more readily and intimately in the kiln. However, there are certain definite practical objections to extremely fine kiln feed, such as loss of kiln dust, unstable material flow through the kiln and greater difficulty in control of chemical composition due to dust loss, and the disproportion of fines from the more easily ground component. Our

Jan 1, 1945

By O. G. Kiel, G. W. Swift

The concept of "a continuous succession of steady-states", which has been applied successfully by Aromfsky and Jenkins to obtain a solution for the nonlinear partial differential equation describing the transient Darcy flow of gas through porous media, is demonstrated to be equally valid for transient non-Darcy flow. A mathematical model, which numerically solves the partial differential equation, is used to check the validity of the succession of steady-states solution. Comparison of sand-face pressure histories compelted by the two methods shows excellent agreement. The utility of the succession of steady-states solution in predicting performance of gas wells rests in the fact that no special computation equipment is required. The development of the succession of steady-states solution leads also to a practical method for determining and analyzing field test data. A method for taking gas-well test data under constant-rate conditions is presented. Experimental data obtained in the field by employing the constant-rate method are presented and analyzed in accordance with the succession of steady-states solution. Analysis of data in this fashion is demonstrated to give direct "in situ" information for reservoir permeability, porosity and turbulence or non-Darcy coefficient. INTRODUCTION The economics of gas production are dependent upon the transient behavior of flow within the reservoir. For production from a finite reservoir, the transient flow behavior can be subdivided into two parts. At first, the transient caused by the movement of the pressure "wave" into the reservoir is of importance. Later in the production history, the pressure-wave movement ceases and the second transient stage of material depletion becomes controlling. For reservoirs of relatively high permeability, it can be shown that the pressure wave moves into the reservoir and stabilizes quite rapidly. In the case of relatively impermeable reservoirs, quite the opposite is true. Although it is theoretically possible to compute the production capability of a well from the properties of the reservoir as determined by static tests and core analyses, more reliable information is obtained by conducting flow tests on the well and thereby obtaining some measure of "in situ" formation properties. For gas wells, there are two basic types of tests in existence: the flow-after-flow method,' and the isochronal method.' Both of these techniques are tailored to obtain data that can be analyzed in accordance with the empirical performance equation: In addition, the isochronal method makes provision for the sluggish nature of pressure-wave movement in "tight" formations by requiring pressure build-up between flows and by stipulating that data obtained on successive flows be analyzed at equal elapsed flow times. It can be demonstrated that either test is valid for reservoirs of high permeability. Further, since it has been pointed out that the pressure wave stabilizes rapidly for reservoirs of this type, tests of relatively short duration will give stabilized information on the performance of a well. Further decline of sand-face pressure and/or production rate may be determined by employing material-balance techniques. Cullender' points out that for relatively impermeable reservoirs the flow-after-flow method gives invalid results. (See Appendix C.) If the isochronal method of testing is used, there are two alternatives: (1) the tests must be conducted for a sufficient length of time to obtain stabilized information (which may require months to accomplish); or (2) some method for extrapolating the results of short-term isochronal tests must be employed. The first alternative is impracticable because of manpower, conservation and economic considerations. Recourse to the second alternative requires some assurance regarding the reliability of the extrapolation technique. Poettmann and SchilsonJ present an empirical method for predicting stabilized performance. The present investigation was originally initiated to determine the reliability of this technique. To do this, a mathematical model was developed to simulate the Darcy and non-Darcy flow of gas through porous media. The model consisted of a finite-difference approximation of the nonlinear partial differential equation which was solved on an IBM 7090 computer. Long-term production histories were simulated by the model and compared against predictions obtained from the Poettmann-Schilson method. As the work progressed, it became apparent that a straightforward predictive equation could be developed by utilizing the concept of a succession of steady-states. As a result, the emphasis of the work was redirected to exploit the advantages of the new method.

Jan 1, 1879

By V. R. Garfias

EVEN before the arrival of Cortes in 1519, the history of Mexico was closely linked to that of its mineral production; the mining activities of the Aztecs being thus described by Clavigero, one of the early historians: In the mountains of Anahuac there abound in veins all kinds of metals, and infinite variety of other fossiliferous products. The Aztecs obtained gold from the countries of the Cohuijques, of the Mixtecas, of the Zapotecas and from various other places. They gathered that precious metal usually in grain, from the sands of the rivers, keeping a certain portion for the crown. They obtained silver from the mines of Taxco, of Tzumpango and others; however, this metal was not as esteemed by them as by other neighboring nations. They had two kinds of copper; one hard, which they used instead of iron to make sickles, lances and all kinds of rural and military instruments and another, soft, with which they made kettles, goblets and other receptacles. This metal abounds mainly in the province of Zacatula and in that of Cohuijques, which at present is in the kingdom of Michoacan. They obtained tin from the mines of Taxco and lead from those of Izmiquilpan, located in the country of the Otomiea. From the tin they made money, and the lead, we know they sold in the market places, but we ignore the uses to which they applied it. They also had mines of iron in Tlaxcala, in Taxco and in other places; but they either had not discovered them, or did not know how to make use of the metal they contained. In Chilapa there were mines of mercury, and in other places there were mines of sulphur, alum, vitriol, cinnabar, cohre and of a white earth which they esteemed highly. As regards mercury and vitriol, we do not know of what use they were to them; the other metals they used in paintings and dyes. There were then great abundance of amber and asphalt-bitu- men of Judea--on the coast of the seas and many cities of that territory paid tribute of one and the other to the kingdom of Mexico. They mounted the amber in gold, and it was only used as ornament and display by them. With the asphalt they made certain perfumes. The following extracts dealing with pre-Colonial gold are taken from the famous "Cartas de Relación" to Charles V, in which Cortea described the progress of the Conquest: . . . here there came two chiefs who owned lands in the valley; one four leagues down the valley and the other two leagues up the valley and they gave me some gold necklaces of little value and seven or eight girls. . . . . . . that day I left the City of Churultecal and traveled four leagues to some villages of the City of Cuasucingo where the natives received me very well and gave me women and pieces of gold. . . .

Jan 1, 1937

By William J. Gillich, Gerald L. Moss

PREVIOUS studies of the shock loading of randomly oriented polycrystalline aggregates have firmly established that, after rather short load duration, hydrostatic compression closely approximates the shocked state.' However, McQueen deduced from pressure measurements with good time resolution that, during shock loading, metals begin to undergo a stress relaxation at the yield stress. He suggested that the relaxation is due to plastic deformation accompanying the change from a one-dimensional compression to a three-dimensional, hydrostatic, compression.' Stress relaxation may occur faster as stress is increased above the yield stress, but the existence of unidirectionally compressed states for finite times suggests that the concept of a unidirectionally distorted lattice should furnish considerable insight into the mechanical behavior of materials subjected to shock loading. Here, a crystallographic analysis is presented for the hypothetical situation where atom motion may be considered as unidirectional which, as indicated above, is a useful extension of the macroscopic concept of shock loading to the microscopic domain. Only motion caused by the com-pressive forces is treated; i.e., lattice vibrations upon which this motion is superimposed, as discussed by Fitzgerald, are ignored.3 The purpose of the analysis to be presented is to develop a description for single crystals of the lattice rotations that occur for idealized uniaxial strain deformation. The usefulness of such an analysis in realistic deformation is to give a method of specification of those properties of an initially distorted lattice which would affect the subsequent deformation. Non-axial complications that arise experimentally, such as off-axis rarefaction waves, must be treated in proper context. Consider the material element shown in Fig. 1 and let the compression be uniform at all regions of the element. Then, any interior point of the element is displaced in proportion to its distance from the base of the element. Accordingly, if the top of a unit element is displaced by an amount, (-K), with respect to the base, a point P(X, Y) will be displaced by (-KY). Crystal planes are, therefore, rotated by the compression. Analysis of this rotation may be accomplished from the geometry shown in Fig. 1 where the line OP is the edge of the plane {hkl} and N is its normal. The orientation of the crystal plane with respect to the shock direction is specified by the angle, before deformation. After deformation the edge of plane {hkl}

Jan 1, 1969

By J. Versluys

A well can flow exclusively through the casing or exclusively through a tubing but can also flow partly through a casing and at the top part through a tubing. The main principles of the flowing of wells under these conditions were explained in the author's former paper.' Practically all factors that influence the regular flow are dealt with therein. The question of irregular flow, however, will be discussed briefly here. As a rule, an irregular flow must be avoided, as it may be assumed that the efficiency is thereby very small, while on many fields it is injurious to the sand of the oil-bearing layer. Periodical flowing often occurs with rising mixtures of gas and liquid. The phenomenon can be explained if it is accepted that two conditions are possible in the mixture; namely, the foam condition and the mist condition. If there is no stabilizer in the liquid, the foam condition can exist only when the liquid forms a greater portion of the volume than the gas. The mist condition, on the other hand, can exist only when the liquid occupies a smaller part of the volume than the gas. The foam condition occurs when there are gas bubbles in the liquid mass, while in the mist condition drops of liquid are disseminated in a gas-filled space. For sake of simplicity, it has been assumed that the mist condition prevails when 50 per cent. or more of the volume is occupied by gas, while with less than 50 per cent. gas the foam condition will arise. For distilled water and for oils which do not tend to form stable foams this is probably approximately true. If this does not hold good, however, two cases are possible: (1) The fields of the two conditions overlap or (2) they do not meet. If the fields of the conditions overlap there is an intermediate field where either of the two conditions can exist, depending on the history of the mixture. Suppose the foam condition prevails first and the gas

Jan 1, 1931

By Leslie W. Austin

ROTARY kiln operators will agree that some of the most severe conditions a refractory must stand occur in the hot zone of a kiln burning Portland cement, dead burn dolomite, magnesite, periclase, and similar materials. Frequently the operator is faced with factors beyond his control which drastically shorten the life of refractories. Shutdown due to mechanical failure can be serious if the period is of sufficiently long duration to cause the dropping of coating or the loosening of the lining. A change in slurry can affect the coating and cause ring buildup. A change in type of fuel and its effect upon the flame can cause a shift in location of the hottest zone. Weekend shutdowns or any other interruption can cause the operator trouble and may damage the refractories, since stopping and starting a rotary kiln is certainly more difficult than stopping and starting a motor. Some operators have tried to set an estimate of damage for each shutdown in equivalent days of running time. Conditions affecting the refractory may be roughly grouped in four classes: chemical attack, mechanical stress, thermal shock, and abrasion. Chemical Attack: The drive to obtain maximum production through a kiln demands maximum operating temperatures, temperatures which are limited more by the ringing up or melting of the clinker. This can cause interface temperatures at the junction of coating and refractory which require the use of a basic kiln block to withstand the chemical attack. Chemical changes take place within the refractory itself, especially in chemically bonded or unburned kiln blocks: These changes cause the formation of the ceramic or burned bond. Migrating liquids or fluxes from the kiln charge have an effect within the refractory and lead to mineral or glass formation. The alkalies, sodium and potassium, migrate into the refractory as silicates, chlorides, sulphates or other salts. They may move under capillary action or may be caused to move by volatilization with condensation in the cooler portion. Mechanical Stress: Concentrated stress may be caused by several factors or combinations thereof. 1-The rings of refractories must be kept tight and rigid within the kiln, and this alone demands considerable force to hold the blocks in place. So that the force will not be concentrated, the blocks should fit the circle as perfectly as possible, with the faces in contact overall. 2-As the kiln is heated, thermal expansion takes place at the hot end of the kiln block. Since this disturbs the plane face it too can cause a concentrated stress at the two ends of the block, and shearing stress can be set up within the brick itself because of the difference in expansion between the two ends. 3-If a lining becomes loose and moves in the shell very severe stress can be set up, and as the kiln rotates this load changes and gives the effect of repeated loading. Permanent expansion of the refractory can also cause severe loading. 4-Not least important, flexing of the kiln is frequently the cause of concentrated stresses. Thermal Shock: Thermal shock, the result of heating and cooling too rapidly, occurs on starting and stopping or when a large patch of coating drops, exposing the bricks. Again, its destructive effect is often the result of phase change, liquid to solid or the reverse; dense refractories loaded with glass-forming impurities are particularly susceptible. Thermal shock is a problem with refractories set in the wall or roof of a stationary furnace, and becomes even more serious in a rotary kiln, the tendency to spall being magnified with movement and concentration of stress. Uniform rate of feed and loading insures both better coating and a more uniform stress. Abrasion: If the refractories do not take a coating, abrasion can become a most destructive factor. Movement of the lining in shell or movement of loose blocks causes abrasion, which is also most destructive if the refractories do not take a coating. An analysis of the problem of basic lining for the hot zone reveals, therefore, a number of desirable characteristics: high refractoriness, basic chemical reaction, resistance to spalling, good strength at all stages, ability to take coating, true sizing, volume stability, and abrasion resistance. Increased demand

Jan 1, 1952

By Rixford A. Beals

It has been observed with considerable accuracy that if the major U. S. mines were moved to Mexico tomorrow, many of them would be losing money. But the companies would continue to operate, losses or not, because they would have to. And some of the newest and most promising low grade ore projects in the U. S. would never have "gotten off the ground" had they faced the equivalent of the mining taxes now in effect in Mexico. No one of the various mining taxes in Mexico seems prohibitive by itself. Taken together, on the balance sheet, however, the picture changes. Production and export taxes alone take from 20 to 40 pct of the gross product value for base and precious metals.

Jan 2, 1955

Report of the Secretary GENTLEMEN Herewith are transmitted reports from the Treasurer and of the principal standing committees of the Institute. To these special reports members are referred for details as to the year's work. Despite the unfavorable business conditions obtaining throughout the year, the Institute was able to carry on its various activities without curtailment and without drawing on the surplus accumulated through previous years. In fact, small additions were made to the Life Membership and various other funds. It is highly desirable that such additions should continue to be made, especially to the Life Membership fund, for reasons reported last year. At present, money must be used from current receipts in order to enable the Institute to fulfill its obligations to those who on joining the organization commuted their dues by a single payment. In addition, with the passage of years the number increases of those who have paid dues forty years or more and who, by reason of age or disability, are unable longer to practise their profession. These men have supported the Institute through their active professional life and it would be a pity to lose them as members through resignation or for failure to keep up their dues. In accordance with the By-laws the Board has authority to advance such members, on application, to the Honor Roll of Senior Members and to relieve them from further payment of dues. It has been the policy of the Board to do this liberally, but to keep up this, as well as to meet other obligations, it is necessary for money to be provided. It has been estimated by the Treasurer that nearly $50,000 additional should be placed in the Life Membership fund as soon as possible to meet these obligations without using current income and to that end it is necessary, not only to avoid running behind currently but to earn, if possible, some surplus each year. The small amount transferred to the Life Membership fund from surplus this year was, as a matter of fact, made possible by certain members paying personally bills that were properly chargeable to the Treasury. Such generosity is common among those active in Institute work and probably no year would have closed with a surplus except for it.

Jan 1, 1929

By Carl F. Floe, Michael B. Bever

THE possibility that carbon may be soluble in copper to a limited extent has been recognized for over a century. The quantitative investigation of this problem, however, requires more sensitive techniques than have formerly been available. Three recent developments have made possible more accurate determinations: the vacuum-fusion method of analysis, the production of copper of high purity and the availability of high-purity refractories, particularly graphite. In addition to its obvious theoretical interest, the problem of carbon solubility in copper is of practical importance. In the production of copper and of high-copper alloys, carbonaceous covers are frequently used. If even minute amounts of carbon are dissolved, insoluble carbon oxide gases will be formed when such metals are poured under oxidizing conditions. A mechanism of this kind could well be one of the principal causes of gas porosity in casting copper-base products. REVIEW OF LITERATURE In 1823 Vivian1 raised the question as to whether copper by overpoling becomes "combined with a minute portion of carbon." Karsten2 asserted, in 1832, that carbon reduces the high-temperature strength of pure copper, so that when the carbon content has reached 0.2 per cent the metal will be brittle at a dark red heat. According to Karsten, carbon contents of o.05 per cent make it difficult to hot-work copper. He also reported that the specific gravity of copper is 8.8969 and that it increases to 8.92 58 if the copper is cemented with carbon and then melted. He emphasized the difficulty of determining analytically the small amounts of carbon present in copper. The metal was removed by wet methods and the residue considered as carbon. At Percy's request, Dick,3 in 1856, carried out various working tests on copper that had been in prolonged contact with carbon, and found that the working properties of the metal had not been affected. He also attempted to determine the presence of carbon analytically. In one experiment the copper was dissolved and the residue was fused with litharge, and in another essentially a combustion analysis was made on a copper sample. In a final experiment, a sample was dissolved and the residue subsequently subjected to a combustion analysis. Indications of as much as o.005 per cent carbon were found, but Dick considered his work inconclusive largely because of the possible interference of sulphur. Percy4 concluded, from Dick's experiments and from some experimental work of his own, that the solubility of carbon in copper had not been established with

Jan 1, 1945

By B. Rao Pothini, Hilmar A. von Schonfeldt

One of the key elements essential to a productive and uninterrupted longwall mining operation is roof control. In several of the Island Creek Coal Company's mining sections, polyurethane has been infused 80 into strata to control severe roof failures in the face and gate entry areas. To date about 50,000 kgs (110,000 lbs) of the chemical have been consumed in a number of applications. Roof-to-floor convergence 60 and differential roof sag have been monitored to determine the need for polyurethane infusion and also to evaluate roof stability following the infusion. Stratascopic observations of the roof formed the basis 40 for confirming the need and also for estimating the required quantities of polyurethane. Both chemical infusion and roof control monitoring techniques have been applied successfully under very adverse roof 20 conditions; substantial production benefits have been realized. Operator acceptance of the system has been very good.

Jan 1, 1981

By S. S. Hedge, J. C. Ferm, J. T. Berger

The coal procedures described in this paper address the problems building a body of coal data that is accurate, precise, readily available, and easy to manipulate. The system is a set of interactive computer procedures consisting of a) data gathering (core hole and geophysical logs, their location, elevation, etc.) and standardized computer printouts, b) the graphic outputs of coded logs (log strips-scale variable) wing on-line electrostatic plotter, c) determination of seam continuity via relative movements of the log strips on an interactive graphic display terminal, d) calculation of the seam parameters (minable seam thickness, volume of non-coal material in the seam, ash and sulfur content of the raw or prepared product, roof and floor characteristics and other attributes relevant to mining), e) posting of seam parameters wing on-line drum plotter controlled by a microprocessor on-line to the minicomputer (PDP- 11).

Jan 1, 1983

By AIME AIME

SCANDINAVIAN countries seem somehow to furnish an amount of talent and leadership far be- yond their population and among them Sweden is possibly at the top. The United States has many eminent citizens born in the latter, country or who are of Swedish descent and the engineers may claim their full share. In fact, the number is so large that a flourishing Swedish-American Engineering Society has been formed, including a number of A. I. M. E. members. Dr. Waldemar Lindgren is more scientist than engineer, though his work in economic geology has contributed directly to the development of many mines, and he is the valued- adviser of a number of our larger companies. Probably he, himself, values most highly the contributions he has been able to make to scientific theories of the occurrence and genesis of ore deposits. His fellow scientists have placed upon these the high mark of approval by electing him to the National Academy of Sciences, and Princeton University in 1916 recognized his position by conferring on him the degree of Doctor of Science.

Jan 1, 1931

By J. M. Gaines, C. H. Herty, M. W. Lightner, H. Freeman

Few subjects have attracted the attention of metallurgists more than oxygen in steel. From the days of Mushet and Ledebur interest in this subject has been increasing, and as additional knowledge has become available, the problem has naturally grown more complex. Instead of using the simple term "oxygen" we now distinguish between iron oxide, silicates of various kinds, oxysulfides, oxygen as gas and oxygen in solid solution in steel. There are five general methods for determining oxides in steel: hydrogen reduction; vacuum fusion; various wet-extraction methods, including electrolytic methods; methods depending on volatilization of the iron away from the oxides; and metallographic methods. For oxygen in solid steel each of these methods has both advantages and disadvantages. The hydrogen-reduction method is of no use on steels above about 0.20 per cent. carbon;' furthermore, it gives only FeO and possibly some MnO. The vacuum-fusion method2 is expensive and gives total oxygen, with the exception of some A12O3, and does not differentiate between the various oxides in which the oxygen exists. Most of the wet extraction methods3 give only the more insoluble oxides SiO2 and A12O3, though the iodine method gives MnO to an uncertain degree (information that may be more misleading than no information

Jan 1, 1930

By William Glenn

The Ritchie grahamite-mines of Ritchie county, West Virginia, were situated near the central part of the upper barren coal-measures

Jan 1, 1895