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By A. C. Fieldner

DURING 1939, 286 by-product coke ovens were completed and put into operation. These included 140 Witputte ovens for the Carnegie-Illinois Steel Corp., at Gary, Ind.; 61 Koppers-Becker ovens for the Ford Motor Co., at River Rouge, Mich.; 65 Semet-Sotvay ovens for the Great Lakes Steel Corp., Zug Island, River Rouge, Mich.; and 20 Curran-Knowtes ovens for the Midwest-Radiant Corp. plant at Mitlstadt, Ill. The Millstadt plant is unique in carbonizing a washed coat containing 3.50 per cent sulphur. The gas contains approximately 2500 grains sulphur per 100 cu. ft.; this is successfully removed with sodium carbonate solution by the Seaboard liquid purification process. The coke is intended primarily for use as a smokeless domestic fuel in the city of St. Louis.

Jan 1, 1941

[Trans. No. Place Date Vol. Page 1, Wilkes-Barre, Pa.* .... May, '71.. 1 3 2. Bethlehem, Pa Aug., '71.. 1 10 3 Troy, N. Y Nov.,'71.. 1 13 4. Philadelphia, Pa Feb., '72.. 1 17 6. New York, N. Y •.... May, '72.. 1 20 6. Pittsburgh, Pa..:.Oct., '72.. 1 25 7. Boston, Mass Feb., '73.. 1 28 8 Philadelphia, Pa.' May, '73.. 2 3 9. Easton, a Oct., '73.. 2 7 10. New York, N. Y Feb., '74.. 2 11 11. St. Louis, Mo.* May, '74.. 3 3 12. Hazleton. Pa Oct.. '74.. 38 13. New Haven, Conn Feb., '75.. 3 15 14. Dover, N. J.' May, '75.. 4 3 16. Cleveland, 0 Oct., '75.. 4 9] [ ]

Jan 1, 1925

By John E. O’Rourke, Kevin M. O’Connor, Pamela H. Rey

INTRODUCTION The resurgence of coal mining activity in the United States, brought on by the spiraling costs of fossil fw1 energy in the Seventies, has come at a time of intense public concern for the quality of the environment. Notwithstanding pressure on our economy to develop alternate sources of fue1 energy to the import of oil, the legislatures of several states have reacted to public concern over the environment by passing strict regulations aimed at con- trolling the subsidence effect s of underground mining. Agencies of the federal government charged with assistance to the mining industry, including the Department of Energy and the Bureau of Mines, have sponsored a number of instrumentation and field measurement projects aimed at the development of subsidence prediction models that can aid the mine operator's task of subsidence control. There are good empirical models developed in Europe for subsidence prediction, but they were made possible by a large body of mining-induced subsidence data collected there over a long period of time. No com- parable subsidence data base exists in the United States, and consequently empirical modeling of subsidence is not a realistic approach for our near term needs. Moreover, the geologic and topographic diversity of the several coal regions in the United States is expected to necessitate the development of several empirical models, each one expected to be relevant to its own region. Because of the time and costs that are likely to be involved in an empirical modeling approach, it is considered more expedient and cost effective to develop a general, mechanistic model for subsidence prediction purposes. In order to develop such a model, it is necessary to investigate and quantify the mechanics of the subsidence process from the mine level up to the ground surface. The series of projects discussed in this paper are designed to achieve this objective and include the following work: (1) the identification of geotechnical instrumentation that will pro- vide mine level overburden and surface subsidence data. (2) a field demonstration of selected instruments, and (3) documentation of case histories for complete subsidence mechanics, using the demonstrated and preferred instruments. An identification of feasible instrumentation and monitoring techniques was completed by Woodward-Clyde Consultants (WCC) in 1977 (O'Rourke and others). This paper discusses a demonstration of those instruments at a mine in Utah, and at two subsequent projects, currently underway at longwall mines in Colorado and West Virginia. 'he latter two projects when complete will provide documented case histories of subsidence mechanics. The process of optimizing subsidence instrumentation and monitoring techniques to the conditions encountered during installation and monitoring for these underground mines is shown to be an evolving one, and one which has had some notable successes to date. INITIAL DEMONSTRATION The initial design and demonstration of selected monitoring systems was carried out at the SUFCO No. 1 mine, near Salina, Utah. The instrumented panel was approximately 152 m wide. 640 m long. and was 290 m to 320 m deep. The mined height of coal. seam averaged 2.4 m. The mining method was room and pillar using continuous mining machines. This method allowed some monitoring of the supported condition during development, and eventually allowed monitoring of a caved system when both chain pillars and room pillars were extracted on retreat. The two instrument systems shown on Table 1 were selected from the earlier feasibility report for demonstration at SUFCO No. 1. Collectively, the two systems, one for a fully-supported mining method and the other for a fully-caved method, incorporate most of the instrumentation to be found within all five systems listed in the earlier feasibility report. The instrumentation includes surface, subsurface and mine monitoring installations. All of the SUFCO instruments selected to meet the specifications of the general instrument types listed on Table 1 were manually operated. That is, data from the installed system could only be obtained while a person was there to physically observe or operate the system readout. Automatic data recording equipment was available for some installations, but the objectives were to keep the systems as simple as possible for the demonstration project. A complete description of the surface, sub- surface and mine level instruments, and the demonstration project results are given in WCC (1982), and selected features are discussed in this paper.

Jan 1, 1982

By A. I. Blank, S. E. Maddigan

Many experimental and theoretical investigations have been made on the processes involved in annealing and recrystallization of metals. Most of these, however, have treated the time element as constant and heat-treatments used have been for relatively short times. Aside from the early work by Carpenter and Elam,' the few that have investigated the effect of time on the processes have usually done so for fairly short time periods. During recent years the growing interest in long-time creep properties of metals and alloys under stress has made increasingly important a better knowledge of the recrystallization during prolonged heating. The recrystallization temperature of 70-30 brass given by Clark and White" in 1932 was somewhat above 400°F. (204°C.) but under 500" (260°C.), whereas in our laboratory recrystallization has been observed in creep specimens at 204°C., the lowest temperature of Clark and White's range. Since the creep properties are quite different above and below the recrystallization temperature, erroneous conclusions can readily be drawn by the application of short-time recrystallization data to creep problems. It was thus considered of both practical and theoretical value to make long-time annealing studies near the minimum recrystallization temperature. In this way useful additions could be made to data on recrystallization temperatures and, since the reactions in this range are relatively slow, additional insight could be obtained into the factors involved in annealing. Several comprehensive reviews of recrystallization processes have been written,3-6 therefore only a brief review of the generally accepted facts will be given here. Though the effects of heat-treatment usually are expressed as related to observations with varying temperatures, it is logical to assume that the same order of occurrence will exist with time as a variable. Thus, we may postulate that with increasing time we mill observe the following

Jan 1, 1940

By S. E. Maddigan, A. I. Blank

Many experimental and theoretical investigations have been made on the processes involved in annealing and recrystallization of metals. Most of these, however, have treated the time element as constant and heat-treatments used have been for relatively short times. Aside from the early work by Carpenter and Elam,' the few that have investigated the effect of time on the processes have usually done so for fairly short time periods. During recent years the growing interest in long-time creep properties of metals and alloys under stress has made increasingly important a better knowledge of the recrystallization during prolonged heating. The recrystallization temperature of 70-30 brass given by Clark and White" in 1932 was somewhat above 400°F. (204°C.) but under 500" (260°C.), whereas in our laboratory recrystallization has been observed in creep specimens at 204°C., the lowest temperature of Clark and White's range. Since the creep properties are quite different above and below the recrystallization temperature, erroneous conclusions can readily be drawn by the application of short-time recrystallization data to creep problems. It was thus considered of both practical and theoretical value to make long-time annealing studies near the minimum recrystallization temperature. In this way useful additions could be made to data on recrystallization temperatures and, since the reactions in this range are relatively slow, additional insight could be obtained into the factors involved in annealing. Several comprehensive reviews of recrystallization processes have been written,3-6 therefore only a brief review of the generally accepted facts will be given here. Though the effects of heat-treatment usually are expressed as related to observations with varying temperatures, it is logical to assume that the same order of occurrence will exist with time as a variable. Thus, we may postulate that with increasing time we mill observe the following

Jan 1, 1940

By L. Dr. Edeleanu

CRUDE petroleum is a mixture of various groups of hydrocarbons and some bodies containing oxygen or sulphur. These constituents possess properties differing considerably one from another and the proportion in which they are contained in the crude oils is also very different. Owing to this complicated composition the practical use of crude petroleum is much restricted. For example it is sometimes used as a liquid fuel. But its employment in this way is uneconomical because various valuable qualities of the individual constituents are not made use of. The rational utilization of petroleum can only be accomplished if the various groups of hydrocarbons are separated. The mixture of hydro-carbons present in the crude oil must be split up in such a way that the hydrocarbons are divided into various groups having certain predominant characteristics and uses. To accomplish such a separation is the aim of the technical refining of petroleum. ORDINARY REFINING BY DISTILLATION AND CHEMICAL TREATMENT Hitherto this has been accomplished by two processes, namely, fractional distillation and chemical treatment of the distillates obtained. Distillation Process The process of distillation consists in the separation of the constituents of petroleum into various fractions, the boiling points of which lie within certain defined limits. The fractions so separated possess certain special qualities in common, which enable them to be applied for specific purposes in practice. For example, we have the fractions known as benzene, illuminating oils, heavy oils, lubricating oils, etc.

Jan 9, 1914

By Harry A. Wahl

Precent fracture design procedures are bared on the total fracture area created. A method to distinguish beI,,.ecn total area and [he propped or effective fracture area has not been available. This paper presents a solution to this problem, applicable to horizontal fractures. The difierences between effective fracture area and torn] area are demonstrared in example calculations. This work is hayed on experimentally determined transport efficiencier of solids in sand-liquid slurries. Newtonian and non-Ne~vtoninn systems are considered. INTRODUCTION Fifteen years after commercial introduction, hydraulic fracturing remains the most successful stimulation technique in the oil field. This success is primarily due to ability of induced fractures to penetrate and alter permeabilities deep within formations. Many fields producing today could not have been developed without the hydraulic fracturing process. Because of wide usage, fracture-treatment design has received a great deal of engineering and research effort. This work, resulting in improved equipment and materials, has increased the benefits from fracture treatments as well as the applicability of the process. A major contribution was the development of fluid-loss additives. Necessarily, the number of parameters to be considered in treatment design has steadily increased, resulting in more complicated design techniques. Almost all present design procedures are based on the precepts set forth by Howard and Fast. Relating the fluid volume lost into the formation, the volume required in extending the fracture, and the total slurry volume injected, they developed an expression for the total fracture area created in terms of pertinent treatment parameters. Fluid loss during treatment was expressed as a function of time for three flow mechanisms. Although modifications of fluid loss equations have been made, the total fracture area concept has remained unaltered. A vast amount of field data indicate that induced fractures must be propped and held open to be effective. A notable exception is the Mesa Verde formation in the San Juan basin. However, analysis of these treatments shows that improved well productivities are obtained when propping agents are incorporated in the treating fluid. Although propped fracture area has been recognized as an important design parameter, a method to distinguish between total area and effective fracture area has not been available. The necessary information on slurry-sand transport in fractures has been lacking. Interest in the propped region of induced fractures is not restricted to areal extent alone. The distribution of sand within fractures is important from the standpoint of fracture flow capacities. Flow capacity affects the increase in well productivity after stimulation. The work of Huitt and Darin4 hows that partial monolayers of sand have large flow capacities compared to thick* dense sand packs. It has been postulated that gelled fluids have the ability to transport sand within the fractures at the deired low concentrations. An early contribution in the area of sand placement in fractures was made by Kern et al.' They studied sand movement in a transparent vertical fracture model. It was observed that the sand tended to settle out in the bottom of the model before moving very far. When the fluid velocity exceeded a certain critical value, all of the sand injected began moving through the crack even though it settled to the bottom. This critical velocity was determined under several flow conditions. Some work on sand movement in horizontal fractures has been reported in Russian publications. Sand movement was studied by Izyumova and Shan'gin' using a transparent "pie-shaped" flow model to simulate a horizontal radial flow system. However, the data were limited, especially in a quantitative sense. Dorozhkin, Zheltov and Zheltow studied the behavior of sand-liquid slurries in a horizontal linear flow model. The quantitative data were restricted primarily to the thickness of sand deposits formed at the bottom of the fracture. An earlier paper provided basic data on the flow of sand in horizontal fractures. This study was designed to yield specific quantitative information on rate of advance of sand particles and pressure behavior under various flow conditions. A comprehensive photographic study was undertaken in a 10-ft windowed flow cell to provide the necessary qualitative and quantitative data. Since the number of potential variables far exceeded the capacity of the initial study, emphasis was placed on the effects of sand concentration, oil viscosity and oil flow rate. A detailed description of these experiments and the results are described in Ref. 9. However. the implications of this work on the fracture design calculations were not discussed. An analysis of these data as well as new data is provided in the following sections. EXPERIMENTAL RESULTS The primary objective of the experimental investigation was to provide information on the rate of advance of the solids in sand-liquid sturries. A 10%-ft long transparent

Jan 1, 1966

By Alan M. Bateman

POSSIBLE postwar trends of the more important world minerals will be determined in part by their present world position and by the acts and forces that have operated during the war period, so it is desirable first to review briefly what has been happening in the foreign field of metals and minerals. When we first entered this war we of the mineral profession were all acutely conscious of our lack of strategic minerals and other materials, which had to be imported in great quantities-minerals such as manganese, chrome, tin, mercury, nickel, and antimony. But we realized also that we had to acquire vast quantities of those minerals of which we had thought we were bountifully supplied. Our assumed domestic abundances turned out to be woefully deficient, and demands also arose for new minerals never before produced in large quantities. Some threescore minerals entered the strategic list of our imports. Ores from new sources had to be sought, developed, and transported. Tonnages in the millions of such bulk materials as zinc, lead, copper, chrome, and manganese flowed to feed our war efforts. Sparsely distributed minerals such as tin, mercury, antimony, tungsten, cobalt, mica, and corundum had to be lured from their rock lairs in greatly increased quantities to feed the hungry maw of war industry, and the rare minerals such as tantalite, columbite, beryl, and quartz crystals had to be developed and procured in quantities never before dreamed of. New uses such as radio and radar created demands for many minerals formerly thought of only as adornments of museum collections and not as pressing industrial minerals. Such minerals were never before mined in quantity.

Jan 1, 1945

By W. F. NETZZEBAND

THE long-hole drill has been used for prospecting underground in the tri-State district for several years, and its value has been pretty thoroughly proved. An attempt was made to get a statement of their experience with the machine from all the operators who were known to have used the machine. The majority of them replied to the questionnaire so that this paper is practically a summary of the experience of the district, together with some practical details taken from the experience of the Eagle-Picher Lead Company. When the drill was first used by the Eagle-Picher Lead Co., it was put in low headings and was mounted on a cross-arm supported by two drill columns. This was found to be a rather awkward method of mounting, because fairly long moves were made and the same drill columns could not be used on any two successive set-ups. The machine was later moved to a mine with high headings so that this type of mounting was found to be impractical. A heavy tripod was tried and found satisfactory, provided care was taken to see that the set-up was solid. The Evans-Wallower Lead Co. and the Century Zinc Co. report using the double post set-up, but the headings are low in these mines. The Commerce Mining St Royalty Co. first used the double-post mounting in high headings by cutting a niche in the wall and setting the post in it. This proved to be a slow and expensive method and was later abandoned for the tripod. The Federal Mining & Smelting Co. has used a tripod throughout its operations. Great care must be taken in using the tripod to see that the set-up is solid. Wherever possible it is advisable to sludge in the legs and let them set a short time before the machine is put into use. Where high bottom is encountered the Eagle-Picher operator found it advisable to drill jack- hammer holes in the bottom and drive the legs into them.

Jan 1, 1930

By GLENVILTE A. COLLINS

(Presented at a Meeting of the Spokane Local Section of the Institute, Feb. 17, 1912, and accepted for publication in the Bulletin. ) WHILE I am not at the present time engaged in active mine-management, my duties permit of extensive study and examination of many mines, mills, and reduction-works in various places throughout the United States. Being much interested in efficiency-work in general, and an ardent reader of writings on this subject by Frederick W. Taylor and others, as applied to manufacturing-plants, and having served my apprenticeship from mucking to the engineering design of ore-dressing and underground plants, I hope that this paper will lead others to investigate the field more fully, to the improvement of general mine- and mill-operations, as well as the advancement, intellectually, physically, and financially, of the employee and his relations with the employer. If a man who is prepared to look closely and observe broadly starts in Canada and zig-zags from camp to camp to southern Mexico, taking time casually to inspect mines, mills, and smelters, he will be pitifully impressed by the great difference in customs, and the general waste of labor, time, and money throughout the country. He will so seldom observe a dollar's worth of results given in exchange for a dollar spent that he will form a poor opinion of operating-efficiency and management. This highly-scientific department, requiring an amount of skill and executive ability equaled in few, if any, of the professions, certainly falls short of the standard established in our greater manufacturing industries. It is easily said that this is due to the diversity of conditions in mining, milling, and smelting. But on second view it must be admitted that there is room for tremendous improvements in nearly every mining-organization. The proposal of such improvements is often met by the argument that any mine

Sep 1, 1912

By R. W. Gurry

When a steel in the austenitic state, with all its carbon in solution, is maintained, at constant temperature, in contact with a gas that removes the carbon from the surface, yet without otherwise altering the composition of the steel, the change in weight of the specimen, after any period of exposure, is a direct measure of the amount of carbon it has then lost. The purpose of the present paper is to show how, by application of established mathematical reasoning based on the fundamental diffusion law and on certain postulates, this loss of weight yields a complete picture of the distribution of carbon throughout a specimen of regular shape after any period of exposure, with all the accuracy required in any practical occurrence of decarburization. Precisely the same is true for the gain in weight during the reverse process of carburization, or for the gradual gain or loss of any element, so long as the steel comprises only a single phase at temperature, provided always that the experimental conditions conform to the postulates. The change in carbon content from surface to center of the specimen is always continuous, when everything is in solution, even though under the microscope the decarburized zone (or carburized rim) may appear to be sharply defined. The experimental procedure is described and some typical results are presented, which are then interpreted by application of the diffusion law. Experimental Procedure Initially an endeavor was made to follow the gain of weight during the process of carburization in a hydrogen-toluene atmosphere, but it was soon found that the specimen became coated with graphite, which could not be removed without some loss of metal; therefore it was decided to continue carburization until the steel was saturated throughout, to remove all graphite from the surface of the specimen, and then to follow the loss of weight during decarburization in a moist hydrogen atmosphere at the same temperature as that used for carburizing. The carburizing procedure has been described in an earlier paper;' it suffices to state here that the carburization lasted about I40 hr. at 760°C. (1760°F.) and 44 hr. at iiio°C. (2030°F.), these periods being long enough-—on the basis of the calculations presented later—to ensure that the specimen was about 99.9 per cent saturated at each temperature. The specimen was a cylinder about 3.8 cm. long and 0.475 cm. in diameter; the materials were carbonyl iron, a commercial low-metalloid iron, and a steel with 3.6 per cent nickel and the usual proportion of other elements. The fully carburized specimen, after cooling at the top of the furnace tube, was placed in a lathe and sandpapered to remove all graphite; then the diameter was measured with a micrometer caliper, and the initial weighing (corresponding to complete saturation) was made. By means of a

Jan 1, 1942

By R. W. Gurry

When a steel in the austenitic state, with all its carbon in solution, is maintained, at constant temperature, in contact with a gas that removes the carbon from the surface, yet without otherwise altering the composition of the steel, the change in weight of the specimen, after any period of exposure, is a direct measure of the amount of carbon it has then lost. The purpose of the present paper is to show how, by application of established mathematical reasoning based on the fundamental diffusion law and on certain postulates, this loss of weight yields a complete picture of the distribution of carbon throughout a specimen of regular shape after any period of exposure, with all the accuracy required in any practical occurrence of decarburization. Precisely the same is true for the gain in weight during the reverse process of carburization, or for the gradual gain or loss of any element, so long as the steel comprises only a single phase at temperature, provided always that the experimental conditions conform to the postulates. The change in carbon content from surface to center of the specimen is always continuous, when everything is in solution, even though under the microscope the decarburized zone (or carburized rim) may appear to be sharply defined. The experimental procedure is described and some typical results are presented, which are then interpreted by application of the diffusion law. Experimental Procedure Initially an endeavor was made to follow the gain of weight during the process of carburization in a hydrogen-toluene atmosphere, but it was soon found that the specimen became coated with graphite, which could not be removed without some loss of metal; therefore it was decided to continue carburization until the steel was saturated throughout, to remove all graphite from the surface of the specimen, and then to follow the loss of weight during decarburization in a moist hydrogen atmosphere at the same temperature as that used for carburizing. The carburizing procedure has been described in an earlier paper;' it suffices to state here that the carburization lasted about I40 hr. at 760°C. (1760°F.) and 44 hr. at iiio°C. (2030°F.), these periods being long enough-—on the basis of the calculations presented later—to ensure that the specimen was about 99.9 per cent saturated at each temperature. The specimen was a cylinder about 3.8 cm. long and 0.475 cm. in diameter; the materials were carbonyl iron, a commercial low-metalloid iron, and a steel with 3.6 per cent nickel and the usual proportion of other elements. The fully carburized specimen, after cooling at the top of the furnace tube, was placed in a lathe and sandpapered to remove all graphite; then the diameter was measured with a micrometer caliper, and the initial weighing (corresponding to complete saturation) was made. By means of a

Jan 1, 1942

By R. G. Green, R. L. Dowdell

LEAD POISONING as a result of eating lead pellets deposited in marsh areas is a cause of high mortality among ducks, geese, and other waterfowl ingested lead shot become trapped in the gizzard with gravel and are slowly ground away by the grit. Absorption of lead as it passes through the intestine in a finely divided state produces severe lead poisoning which is usually fatal. Ducks and geese with lead poisoning develop first a typical green diarrhea. Later, paralysis of the wing muscles prevents flight. As the poisoning continues with further grinding of the shot trapped in the gizzard, increasing paralysis reduces the bird to helpless-

Jan 1, 1937

By J. B. Morrow

AMONG the most notable of Canada's many contributions to the personnel of the mining industry in the United States is J. B. Morrow, born in Halifax, Nova Scotia, April 9, 1886. Soon after completing his schooling at Dalhousie University in 1906 he emigrated to Arizona and Kew Mexico, via Cobalt and Larder Lake, Ontario. After preliminary experience in sampling and mucking he was employed by the Phelps Dodge Corp., first as chemist at the Copper Queen smelter, then, in 1908, with the Corporation's Stag Canyon coal branch at Dawson, N. M., in various capacities fro111 chemist to coke oven and coke department superintendent, and finally as general outside superintendent. While with Phelps he had some contact with the late Dr. Douglas, of whose industrial methods he has always been a great admirer.

Jan 1, 1937

By Norman P. Goss

The Chairman.—Thank YOU, Mr. Goss Gentlemen, I believe we have heard one of the finest papers, especially since Mr. Goss has been very generous in his frank discussion of continuous casting. One point he has brought out which 1 think some of us have not thought through to the same extent that he has—that the continuous casting process offers the small producer an opportunity to compete with the larger, more conventional and presumably better established industries. The meeting is now open for discussion. Are there any questions concerning the first two papers? J. A. Malone.*—I should like to ask Mr. Goss whether there is any special problem involved in the first part, the upper part of the mold before he gets to the first graphite lubricant area. N. P. Goss.—You mean in the forming chamber where chilling first takes place? J. A. Malone.—Yes. N. P. Goss.—So far I have not had any trouble in this part of the setup. My only

Jan 1, 1945

By Robert L. Braun, Arthur E. Lewis

A contained nuclear explosion is proposed to produce a chimney of broken ore well below the water table. After the chimney is filled with water and reaches hydrostatic equilibrium, oxygen, under pressure, is introduced near the bottom of the mass of broken rock. The increase in solubility of oxygen at high hydrostatic pressure is sufficient to initiate the oxidation of the primary sulfides, chalcopyrite and pyrite. The oxidation and dissolution of these sulfides produces enough heat to increase the temperature of the ore and water in the chimney as much as 100° to 150°C. The rate of dissolution of chalcopyrite exposed to oxygen-saturated solutions becomes so rapid under these conditions that the rate of copper extraction becomes limited by the accessibility of chalcopyrite to the solutions. Means of solution control and distribution of oxygen in the chimney have been examined in some detail. A calculational model utilizing experimentally determined solubility rates is utilized to estimate the temperature rise in the chimney and the rate of copper recovery as a function of initial temperature, sulfide content of ore, and size of ore particles. It is concluded that the high pressure and high temperature obtainable in a large ore mass broken by nuclear explosives promise the rapid and economic recovery of minerals not considered soluble by conventional in-situ leaching methods. The method should be broadly applicable to the kinds of deep deposits that must be depended on for future production and with minimum disruption of the environment.

Jan 1, 1974

By B. M. Larsen, K. Heindlhofer

THIS paper describes a relatively simple electrical apparatus that, through the close analogy between the flow of heat and of electricity, enables one to solve quickly and with satisfactory accuracy many complex problems in heat flow. This device, developed in 1935, has proved especially useful in the solution of certain practical problems relating to the design and efficiency of regenerators for an open-hearth furnace or coke oven, yielding within a few hours information that would take weeks or even months to acquire by mathematical1.2 or experimental3 methods of comparable accuracy. Its description now is prompted by growing interest in such analogues, as shown by several recent papers.4.5 The analogy between flow of heat and of electricity appears to have been recognized first by Maxwell who, in his famous Treatise on Electricity and Magnetism (1881) says: The analogy between the theory of the conduction of electricity and that of the conduction of heat is at first sight almost complete. If we can take two systems geometrically similar, and such that the conductivity. for heat at any part of the first is proportional to the conductivity for electricity at-the corresponding part of the second, and if we also make the temperature of any part of the first proportional to the electric potential at the corresponding point of the second, then the flow of heat across any area of the first will be proportional to the flow of electricity across the corresponding area of the second. .. Thus, in the illustration we have given, in which flow of electricity corresponds to flow of heat, the electric potential to temperature, electricity tends to flow from places of high to places of low potential, exactly as heat tends to flow from places of high to places of low. temperature He noted, however, that this analogy is restricted: ... there is, however, one remarkable difference between the phenomena of electricity and those of heat. Suspend a conducting body within a closed conducting vessel by a silk thread, and charge the vessel with electricity. The potential of the vessel and of all within it will be instantly raised, but however long and however powerfully the vessel be electrified, and whether the body within be allowed to come in contact with the vessel, or not, no signs of electrification will appear within the vessel, nor will the body within show any electrical effect when taken out. But if the vessel is raised to a high temperature, the body within will rise to the same temperature, but only after a considerable time, and if it is then taken out it will be found hot, and will remain so till it has continued to emit heat for some time. The difference between the phenomena consists in the fact that bodies are capable of absorbing and emitting heat, whereas they have no corresponding property with respect to electricity. According to this statement the application of the analogy would be limited to problems of steady flow that do not involve heat-capacity effects. In spite of this

Jan 1, 1945

By F. H. Bunge, W. H. Jr. Dailey

This paper covers an investigation of the magnetic roasting characteristics of several iron ores when treated in the form of small pebbles (1/8" to 1/2" in size), and in the form of balled fines. The roasting treatment was carried out with apparatus capable of very close control of time, temperature, face velocity, and per cent combustible in the reaction gas. The effect of rapid initial heating was not studied although it is believed that this has a major effect on the results when processing solid pebbles. The test equipment is a fixed bed type, with such a wide range of gas velocities, temperature, combustible content and etc., that the results obtained can be made to approximate those from various commercial roasting processes. The data presented in this report covers reaction rates, effect of processing variables on silica in the concentrate, flow resistance of beds, and to a limited extent, the effect of particle size. The work is far from complete and raises many more problems than it gives answers for. We believe, however, that much of the information will be useful to those engaged in investigation of magnetic roasting processes. We measured the time required for various degrees of completion of the reaction of hematite to magnetite, for finely pound material in balled form and for carefully sized crushed ore. Measurements were made for a variety of Minnesota and Labrador ores. This report covers an ore requiring fine ginding (-325 M) for liberation (Lower Kevin) and an ore requiring coarser grinding (-100 M) for liberation (Upper Olson). These ores represent approximately the range of characteristics for a group in the west end of the Mesabi Range. Our data shows that the reaction rate is very fast for the finely ground material and that tests are readily reproducible. The reaction rate of the larger size material, in the range of 1/8" to 1/2", is much slower and the results more erratic. We found that for the ores tested, the percentage of silica in the Davis tube magnetic concentrate was a function of iron recovery. Normally the concentrate had a low and relatively uniform percentage of silica up to a critical value of recovery. Above this critical recovery value the percentage of silica increased very rapidly. For example, for one particular ore roasted in the form of 3/8" diameter balls made from -28 mesh fines, the silica remained at about 7% to 8% until the recovery exceeded about 93%. Increasing the recovery beyond 93% resulted in over 25% silica with the additional recovery. The degree of conversion of hematite to magnetite (% completion of roast) required to obtain 93% recovery for balled material, varied inversely with the gas flow rate. Percentage silica in the concentrate resulting from roasting 3/16" and 1/2" solid material was relatively erratic. However, for varying degrees of iron recovery the lowest silica percentages corresponded to those obtainable when roasting fines. It is thought the probable reason for the erratic values was the variation in shattering or cracking of the pebbles during initial heating and roasting. There is some indication that very fast initial heating will greatly increase the permeability of the individual particles of ore to gas flow so that the reaction rate for coarse sizes will approach that obtainable with balled fine material.

Jan 1, 1961

By David LeCount Evans

Not only E. B. Mayo but also W. C. Lacy, who apparently urged the preparation of this analysis, is to be commended. Regional thinking of this type is needed to assure future success in the never-ending search for new mineralized and petroliferous districts. As is usually the case, here is a regional study that will be read by the mining geologist alone. It is ironic that several of the trends established in this study have suggested themselves in northern mid-continent, detailed, and regional studies. These, where established, have offered new keys to petroleum exploration and have provided a possible basis for unraveling a number of broad generalities. The oil geologists, active in Colorado, Kansas, and Oklahoma, would find much food for thought in Mr. Mayo's projections.

Jan 6, 1959

[NOTE.-The following discussions of papers contained in this volume are printed without regard to order of succession. It has been impracticable to secure from the various parties, corrected reports of their contributions in time to effect any particular desired arrangement in this respect. The papers of Messrs. Pourcel, Osmond and Sauveur, were considered at Chicago together with others of cognate character ; and the whole discussion will be found in vol. xxiii., under the head, " Physics of Steel."]

Jan 1, 1894