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By J. R. Thoenen

The Bureau of Mines has used various sizes of core barrels above 2 in. and below 10 in. in diameter to core manganese, potash, coal, brown iron ore and bauxite. The paper describes in some detail the methods and types of equipment used to obtain maximum sampling accuracy. Introduction On December 11, 1946, R. D. Longyear, in his capacity as Chairman of the Subcommittee on Exploration Drilling, wrote the author requesting him to prepare a paper presenting the collective ideas of engineers in the Bureau of Mines on the design, standardization and application of core barrels using diamonds or other hard cutting media for drilling holes larger than two inches and less than ten inches in diameter. In subsequent correspondence it was indicated that similar papers covering the experience of other government agencies would be solicited and all such papers received would be combined in a symposium on the subject for discussion at the March 1947 meeting of the Mining Methods Committee AIME. In soliciting such information from other Bureau engineers, it developed that most Bureau experience had been confined to standard core size, two inches or less in diameter, and that larger sizes had been used only for special purposes. It is hoped the data contained herein will be of help to other operators in solving problems encountered in the field. Acknowledgments This paper was made possible by the request of Lowell B. Moon, Chief, Mining Division, Bureau of Mines, to all Division engineers to send to the author any data they had on the subject. Engineers of the Mining Division contributing were: M. H. Kline, Chief, Raleigh Branch. Paul T. Allsman, Chief, Salt Lake City Branch. J. H. Hedges, Chief, Tucson Branch. C. H. Johnson, Chief, Rolla Branch. A. M. Evans, Mining Engineer, College Park Branch. Wing Agnew, Engineer in charge, Mount Weather, Virginia. Andrew Brown, Mining Engineer, Tus-caloosa Branch. In addition Albert L. Toenges, Supervising Engineer, Bituminous Coal Mining Section, Pittsburgh, contributed his experience in coring coal beds. The author's experience in the use of cores within the limits stated has been confined to the brown iron-ore work described by Brown and coring bauxite and clay in Arkansas. Design and Standardization of Core Barrels Bureau engineers are primarily interested in obtaining core that will best represent

Jan 1, 1949

By L. C. Graton

Although marked by numerous well-known attributes of its own, gold does not possess a kind and range of physical, chemical and geological characteristics wholly different and apart from those of other metals. Instead, it is merely one of the family of metals, with its individual and distinctive traits subordinate to the underlying family relationships and resemblances. The geologist concerned with pure science will pursue, therefore, the same general course and will examine the same broad kinds of facts and interrelations when studying the occurrence of gold as when studying that of copper or cadmium, or any other metal. But when we come to consider the use and economics of the metals, we discover that gold differs strikingly from all the others. Gold, in short, is unique, not by virtue of its inherent characteristics, but because of a peculiar and concerted psychological regard in which it is held. It will be evident, therefore, that the geologist who would deal with gold supply must give far greater weight to economic considerations than is required in his contacts with any other metal. If the geologist be called the scientist of occurrence, and the economist the scientist of use, the economic geologist stands as the necessary link between them. Perhaps it is in part because the economic geologist has made himself more familiar with the science of occurrence than with the science of use and has thus in some degree failed to bridge effectively the gap between the two fields, especially with regard to gold, that the usen1 of gold now appear to be in a state of general concern and even of alarm for the security and adequacy of future supplies. In the case of no other mineral commodity do the users, as a rule, trouble themselves greatly about the adequacy of supply except in so far as that may affect the price which they shall have to pay for the commodity. Oversupply, with resulting low price, they regard as a gift of good fortune. As to long-term undersupply, they are generally content to go ahead on faith, leaving the producer to discover as best he may the means for meeting their requirements or the inventor to find a substitute. But history has shown that for gold a different situation exists. While

Jan 1, 1931

By T. Cameron Kenney

INTRODUCTION Whereas the design of rock slopes in open-pit mines is done largely by mining engineers and geologists, the design of slopes in overburden at this point in time is a problem for which civil engineers or geotechnical engineers are best prepared to deal. The reasons for this situation are to be found in the educational curricula and the technical journals of the two groups, where soil mechanics has received little attention by mining engineers and geologists, and rock mechanics has similarly received little attention by civil engineers. In ten years' time this paper will hopefully be considered by young mining engineers to be a repeat of the material that they studied at university. However, even in ten years time I believe that the civil (or geotechnical) engineers will be extensively used as consultants on overburden- slope problems of open pit mines because mining companies will find this more expedient than maintaining their own geotechnical staff, special field equipment and special testing laboratories. For this reason, the purpose of this paper is not to condense several university soil mechanics courses into a twenty-page text for mining engineers and geologists. Rather, the purpose of the paper is to offer a general explanation of various factors affecting slope stability so that mining engineers and geologists will have a better understanding of the behaviour of overburden soils in slopes. A great deal has been written in soil mechanics literature on the subject of slope stability. No attempt will be made to reference all this material but rather only a selected number of references will be cited. Excellent general treatments of the subject of stability of overburden slopes are available (1,2,3,4). Further information of a more specialized nature is to be found in such publications as the Journal of the Soil Mechanics and Foundation Division of the American Society of Civil Engineers, Geotechnique (printed by the Institution of Civil Engineers, England), Canadian Geotechnical Journal, and the proceedings of the conferences of the International Society for Soil Mechanics and Foundation Engineering. FACTORS INFLUENCING SLOPE STABILITY There are two general scales of slope-stability problems, gross stability and local stability. Gross stability refers to large volumes of soil, and gross instability would involve large rotational-type shear failures. Local stability refers to something much smaller and examples

Jan 1, 1972

By Dara P. Antia, Morris Cohen, Frank S. Gardner

THERE is a conspicuous lack of information in the literature on the precise role played by residual quantities of austenite in heat-treated steels. While retained austenite may be expected to have significant effects on such important properties as the impact resistance of tools and carburized parts and the dimensional stability of dies and gauges, attempts to study these problems systematically have suffered from the absence of a reliable technique for ascertaining absolute amounts of austenite. With such a technique, not only could the relation between residual austenite and service behavior be investigated, but the chemical and heat-treatment factors that control the quantity of the austenite could also be established. Thus, the retained austenite content could then be regulated in accordance with the results desired. The presence of retained austenite may be inferred by observing the changes in properties (hardness, specific volume, electrical resistance, etc.) due to its decomposition on subatmospheric cooling1 or on tempering,2 but these indirect measurements are not readily translated into percentages of austenite. Quantitative determinations have been achieved in special cases by means of dilatometric3 and magnetic4,5 measurements; but the former procedure requires that observations be conducted during the hardening and involves difficult calibrations that limit its applicability, while the magnetic procedure is very sensitive to extraneous influences and depends upon assumptions that can only be considered as approximate in an absolute sense. Furthermore, both the dilatometric and magnetic effects are volume properties, and cannot be conveniently utilized to explore variations in retained austenite from point to point in a specimen. Some microstructures lend themselves to accurate evaluation of retained austenite contents by metallographic methods,3 but such instances are not too common, and at best, the procedure is tedious. The characteristic X-ray diffraction lines of austenite permit positive identification of its presence; and in the present paper the intensities of these lines, or the corresponding densities* on photographic film, are employed to measure the amount of the retained austenite. In order to cancel the effect of uncontrollable variations in the X-ray exposure and film-development conditions, a standard reference line is superimposed on each film by maintaining a foil of aluminum in the path of the incident X-ray beam during the entire exposure. With different samples of steel and the same foil, the ratio of the density of some one austenite line to the density of

Jan 1, 1943

By D. P. Harris

This paper surveys a few of the quantitative exploration models that might be of interest to an ex-plorationist seeking to apply methods of operations research to mineral exploration. A general development of each model is presented, and the model is evaluated relative to the exploration activity. Finally, a philosophy of exploration and mineral resources is presented, and a possible exploration strategy incorporating concepts of some of these models consistent with this philosophy is proposed. The high cost of conducting an effective exploration program has generated an increasing interest in methods of optimizing the allocation of the resources of a firm engaged in mineral exploration. As a step towards this, mathematical models have been formulated which are designed to quantify those variables of mineral exploration in such a manner that they can be integrated with all phases of the firm's operations so as to optimize its profit objective. QUANTITATIVE MODELS General: Exploration models express at least two concepts: mineral occurrence and effectiveness of search. In simplest terms, an exploration model might be formulated mathematically as follows: P(X) = F(X) . G(X), where P(X) = the unconditional probability of discovery of X deposits, F(X) = the probability of occurrence of X deposits, and G(X) = the probability of discovery of X deposits, conditional upon their existence in the search area. With these general models as a basis of reference, some of the specific exploration models are examined below. The Allais Model: DEVELOPMENT - M. Allaisl performed the first study in which a philosophy of exploration was formulated into a probability framework. His objective was to estimate the economic profitability of the exploration of the Algerian Sahara. Allais divided the Algerian Sahara into blocks of land (called cells) 10 km square and defined the random variable, X, as the number of mining districts per cell. Thus, F(X) would describe the probability of 1, 2, or n mining districts occurring within any cell of the search area. Allais reasoned that his best information as to the form of the distribution, F(X), was the number of mining districts per cell that had been found in well explored areas in the world, such as the Western States of the U.S. He found that the Poisson function produced a reasonably good fit to the distribution of districts in these explored areas: where? is a parameter, such as the average number of districts per cell. Thus, by determining the value

Jan 1, 1968

By J. T. Berling, J. B. Conway

MANY studies have been devoted to the correlation of low-cycle fatigue behavior. Several of these have also been concerned with the identification of an effective approach to the prediction of low-cycle fatigue behavior from short-term tensile data. Perhaps the first such approach was that reported by coffin1 in the form: where is the plastic strain range, Nf is the number of cycles to failure, and c is a constant characteristic of a material. In this analysis by Coffin it was reasoned that in a short-term tensile test the value of Nf could be considered as equal to a , in which case the value of c is interpreted as the tensile ductility, f, measured in such a test. If, therefore, the Coffin equation is assumed to be applicable to a given material, it is a simple matter to predict the low-cycle fatigue behavior. Once the tensile ductility is known, this point is located at Nf = 1/4 on a log-log plot of vs Nf and a line is drawn through this point with a slope of to yield a prediction for the fatigue life. Actually, while this equation is quite useful it is not generally applicable, for experiment has shown that the value of —$ does not reflect the relationship between and Nf for all materials or even for a given material over all temperature ranges. An equation similar to the Coffin equation was prepared almost simultaneously by Manson.2 This expression had the form: In this case the exponent on Nf was not assigned any particular numerical value in accord with the various values of this exponent which had been observed for different materials and at different test conditions. Because of this characteristic it will be recognized that little use can be made of this expression in predicting low-cycle fatigue results. A fairly effective expression for use in predicting fatigue behavior was proposed by Manson3 based on a study of numerous sets of experimental results. This relation (Method of Universal Slopes) makes use of modulus of elasticity, ultimate strength, and tensile ductility, and assumes an exponent on Nf equal to 0.6 in representing the plastic strain range contribution to total strain range. While this equation of Man-Son does not yield completely accurate results it must be recognized as being the best means available at

Jan 1, 1970

By C. W. Stratford

[During the last few years, the necessity for development work has been generally recognized by executives throughout the oil industry, resulting in greatly accelerated progress and the adoption of many noteworthy improvements in refining methods and equipment. Several years ago, the Associated Oil Co. decided to improve distillation methods with the object of reducing refining costs. This extremely interesting work was entrusted to the writer, and W. S. James, now Chief of Research for Studebaker Corpn. of America, was selected as the principal collaborator. The latter contributed much during his two years with the Associated Oil Co., to the development work that has followed. The writer extends to the Associated Oil Co. his appreciation for permission to disclose the details of distilling equipment. In petroleum refining the principal requisites of good economics are the separation of high-priced distillates from those of lower price; maxi-mum yield of any desired distillate; lowest capital investment in refining equipment; lowest cost of operation and maintenance, and the best adaptability and flexibility of the same refinery equipment for handling crudes of widely varying characteristics. The first two items mentioned, separation and yields of distillates are determined by efficiency of fractionating equipment,. Discussion in this paper is chiefly concerned with oil-heating equipment, combustion and furl economy. It has long been well known that velocity plays a very important part in all heat transfer systems. Any betterment in specific transfer. rates in such systems must. always involve velocity. Realizing this fact, IV decided to adopt as a basic principle, the employment of energy to impart velocity required for high transfer rates through a heating diaphragm, and our method of modernizing obsolete shell stills is founded on this principle. Mechanical energy is usually cheap and its rational rspcntliture is returned in the form of greatly increased heat transfer rates, on both oil and gas sides of the sheet. Certainly there is nothing new in this principle, the only novelty being that of our peculiar method of application On the oil side (Fig. I) use is made of a centrifugal pump to jet the oil against the heated sheet thereby creating a high velocity sheet flow over the entire fired area. Such a pump is one of the most efficient machines, so far developed, for moving fluids. 'I'he oil, under pressure impinging

Jan 1, 1928

By Morris Cohen, Dara P. Anita, Frank S. Gardner

There is a conspicuous lack of information in the literature on the precise role played by residual quantities of austenite in heat-treated steels. While retained austenite may be expected to have significant effects on such important properties as the impact resistance of tools and carburized parts and the dimensional stability of dies and gauges, attempts to study these problems systematically have suffered from the absence of a reliable technique for ascertaining absolute amounts of austenite. With such a technique, not only could the relation between residual austenite and service behavior be investigated, but the chemical and heat-treatment factors that control the quantity of the austenite could also be established. Thus, the retained austenite content could then be regulated in accordance with the results desired. The presence of retained austenite may be inferred by observing the changes in properties (hardness, specific volume, electrical resistance, etc.) due to its decomposition on subatmospheric cooling1 or on tempering,2 but these indirect measurements are not readily translated into percentages of austenite. Quantitative determinations have been achieved in special cases by means of dilatometric3 and magnetic4,5 measurements; but the former procedure requires that observations be conducted during the hardening and involves difficult calibrations that limit its applicability, while the magnetic procedure is very sensitive to extraneous influences and depends upon assumptions that can only be considered as approximate in an absolute sense. Furthermore, both the dilatometric and magnetic effects are volume properties, and cannot be conveniently utilized to explore variations in retained austenite from point to point in a suecimen. Some microstructures lend themselves to accurate evaluation of retained austenite contents by metallo-graphic methods,3 but such instances are not too common, and at best, the procedure is tedious. The characteristic X-ray diffraction lines of austenite permit positive identification of its presence; and in the present paper the intensities of these lines, or the corresponding densities* on photographic film, are employed to measure the amount of the retained austenite. In order to cancel the effect of uncontrollable variations in the X - ray exposure and film - development conditions, a standard reference line is Superimposed on each film by maintaining a foil of aluminum in the path of the incident X-ray beam during the entire exposure. With different samples of steel and the same foil, the ratio of the density of some one austenite line to the density of

Jan 1, 1943

By Benj. F. Tillson

To most mine operators, it seems evident that there is a drill-steel problem, although under certain conditions the amount of drill-steel breakage does not appear serious. What is at fault? It may be one or a combination of circumstances. The development of rock drills to the hammer-drill type in place of the old reciprocating piston drill, probably is one important cause for the greater steel breakage. Perhaps the manufacturers of drill steel have failed to realize what alloys are needed for this new service or have overlooked the changes in the art of rock drilling. Although suitable alloys are provided, they may not be SO handled in the manufacturing process as to be in the best condition to withstand the demands of rock drilling. The mine operator may be at fault in desiring to use the smallest possible drill-steel section in order that the gage of the drill bits may be correspondingly small and the amount of footage drilled per unit of labor may be greater; or the black-smithshop practice at the mines may need improvement. The miner who uses the drill steel may also require more intensive supervision and education. Again, the manufacturer of rock drills may have failed to study the types of blows the steel alloys will withstand satisfactorily and which their tools are delivering and so he may not know whether or not a different design of rock drill would equal or excel their present drilling speeds without treating the drill steel so severely. All of these hypotheses probably have their supporters. On the other hand, perhaps we are seeking too much service from drill steel and we need a fuller realization of the fatigue strains developed and should prepare to relieve these by a periodic heat treatment of the steels. However, we do not find any proof that any of these suppositions may be held responsible for the drill-steel breakage attendant to mining. The proposed investigation of this matter by the U. S. Bureau of Mines is fully warranted in the promotion of the conservation of labor and material, and the safety of the workmen. The great range of field conditions, as well as the scope of the research, requires the energetic cooperative support of many interests. Various manufacturers of steel,

Jan 1, 1922

By S. S. Raymond, C. R. Hayward

In reheating quenched steel to remove part of the hardness, the softening effect has generally been considered to be a function of temperature and time. The temperature effect is well known, and long before pyrometers were heard of the blacksmith was able to do a good job of tempering, by rule-of-thumb methods and experience in judging temperatures. Modern conditions, which demand steel that will withstand the severest tests, require that the heat treatment be carried out with every possible precaution to secure the best results obtainable. Pyrometers and heat-treatment furnaces of many types are on the market and improvements are continually being made so that it is now possible to regulate the temperature in heat treatment very accurately. There is still a question regarding the time that the steel should be subjected to treatment. It is customary with all operators to insure the desired temperature throughout the specimen and it is generally supposed that a longer treatment of a hardened steel produces a further softening but there are few published figures showing the exact effect of time of treatment at constant temperature. A search of the literature disclosed several brief statements that the tempering effect was a function of both time and temperature, but in no case were any figures given. The opinion is very generally held that the well-know tempering colors are accurate indicators of the degree of tempering. This is disputed by Brearley (The Heat Treatment of Tool Steel, page 102) who states: It has been said that the result would be the same in respect to both hardness and other properties whether the colors were obtained by a shorter heating at a higher temperature or a longer heating at a lower one. This, to say the least, is a very doubtful conclusion, and is certainly not borne out by mechanical tests on oil-hardened and tempered motor car steels which, after tempering for periods varying from 15 min. to 2 hr., show no very great bifferences. The present investigation had for its object the obtaining of some definite data regarding the effect of time, which might serve as a guide to those engaged in the heat treatment of steel. The Rhode Island Tool Co. cooperated by furnishing the steel and machining the test specimens.

Jan 1, 1917

By Ralph A. Sherman, E. R. Kaiser

The remarkable increase in the distribution of the small underfeed stoker for use in furnaces and boilers in small industrial plants, apartment houses and homes has brought producers and distributors of bituminous coal to consider the problem of which coals and which sizes are best suited to this market. Many papers have also appeared, mostly in the trade journals, discussing the problem of the combustion of various coals and various sizes of coal in small stokers. Much difference of opinion has been apparent in these articles; due often, it would appear, to a misunderstanding of the fundamentals of the process of combustion in the stoker fuel bed. During the past year and a half, a program of research has been conducted at Battelle Memorial Institute: (1) On the process of combustion in the fuel bed of the small stoker, sponsored by Battelle Memorial Institute, and (2) on the relation of the characteristics of bituminous coals to their performance on small underfeed stokers, sponsored by Bituminous Coal Research, Inc. As a result of this program of research, two publications have been made, one1 dealing with the problem of clinker formation, and the other2 with the relation of the size of the coal fed to the stoker hopper to that of the coal that reaches the retort to be burned. The experimental research on the relation of size to the performance of the coal is being actively continued. A publication of Bituminous Coal Research, Inc. presenting the data obtained on the performance of several sizes of four typical bituminous coals will appear shortly. Because of the early appearance of that publication, the present paper includes few numerical data. The purpose of this paper is to follow the coal from the hopper through the furnace with a discussion of the various actions that occur, in the hope that it will lead to a clearer understanding of the relation of the type of coal, the size of coal, and other characteristics, to the performance. The authors do not pretend to have obtained the answers to all the complex questions involved; many unanswered questions will be proposed on which future research work is planned.

Jan 1, 1938

By Jos. Van Ackeren

Although the Siemens regenerator principle was introduced into byproduct coke-oven design about 40 years ago, many problems of construction, and particularly of heat distribution and pressure conditions, have not been fully solved. Heat should be applied to the walls of a coke oven in such a way that the coking of the charge of coal will be completed everywhere at the same time, and at approximately the same temperature. This means that the application of heat should be uniform from the top to the bottom of the coal mass (except for the thin layer at the top that is purposely kept at a somewhat lower temperature to reduce cracking of the byproducts); also that a little more heat must be applied to the coke end than to the pusher end, because the coal mass is a little thicker at that end. As a modern coke oven is about 40 ft. long and 12 ft. high, a real problem is involved in the proper application of heat to the oven walls so as to secure quick coking time (without endangering the walls through local overheating) and produce coke made at a uniform temperature. Design of Ovens In all regenerative ovens, the points of combustion are arranged in duplicate sets, one set operating in one-half the area of the heating wall and the other set alternately operating in the other half. Because of the reversal of the flow of gases, the points of maximum and minimum temperatures are alternately located at the same places, thus preventing dangerous local overheating. The practicability of the principle of reversal of flow seems to have been recognized at an early date, and has been applied with every conceivable flue arrangement, combustion chamber, and means of air and gas supply. To summarize the various principles that have proved useful for the control of oven-wall temperature, the best practice seems to have resulted from the acceptance of the use of vertical flues; the separate supply of air and gas to the base of these flues, with the resulting flame

Jan 1, 1923

By Richard W. Smith

Kyanite, long known to occur in Georgia, did not excite coimmercial interest until about 1930. Investigation1 revealed two main types of deposits: (1) separate kyanite crystals embedded in mica schist; and (2) crystal aggregates of kyanite associated with quartz in small and very irregular veins. The second kind at first sight appeared to be the best source of supply. Large boulders or dornicks of kyanite with more or less quartz were found on the surface at many places throughout the Piedmont and Highland sections of the state, but prospecting failed to disclose a sizable vein. These dornicks seem to be a surface accumulation from small veins or lens-shaped masses not more than one or two feet thick, and with a horizontal extent of not more than a few feet. 'rile larger surface accumulation of kyanite dornicks, where not too badly stained by iron oxide, may prove to be marketable, but it is extremely doubtful whether a vein large enough to mine will ever be found. In 1932 deposits of the kyanite-mica schist were known to occur in two places northwest of Clarkesville, in Habersharn County. In 1934, at the request of and in cooperation with the Georgia Geological Survey, the United States Geological Survey made a thorough investigation2 of the deposits and found that the two known areas of kyanite-mica schist in Habershain County were but a part of an unsymmetrical, U-shaped belt (Fig. 1) with a western limb extending into Rabun County and somewhat longer than the eastern limb. The total length of the belt is about 30 miles. The width of outcrop ranges from 100 ft. to 1/4 mile or more. Deposits of kyanite-mica schist of very doubtful commercial importance were found in several other counties. Only the deposits of this kyanitc-mica schist belt in Habersham and Rabun counties will bc discussed in this paper. Geology The kyanite-mica schist of Habersham and Rabun counties occurs near the northern cdge of the Piedmont Upland in metamorphic rocks of pre-Cambrian age3. These rocks probably were deposited as sedimentary

Jan 1, 1938

By Harlowe Hardinge

THE sound made by ball, pebble and rod mills has long been used by the operator as the "telltale " of their operation. The nature of this sound depends upon local conditions and the type of mill used. By experience an operator can tell whether the mill is running properly or not. Some operators are able to detect the difference in sound much better than others and get better results running the same mill under the same conditions. The automatic operation of a mill using sound as the fundamental means for maintaining control presents many problems. The satisfactory solution of these problems requires, for given operating conditions, a greater average output, with improved product for subsequent processing, than can be obtained by manual control. RELATION OF SOUND TO USEFUL GRINDING ENERGY Experience has taught us that there is a difference in character as well as in intensity of sound between a mill grinding wet and one grinding dry, in open or closed circuit, to obtain a coarse or fine product, on the same material, to say nothing of the effect with a variety of different materials. Broadly speaking, a wet-grinding mill operates best at a lower sound level than the same mill grinding dry, with other conditions the same. Several reasons for this variation in sound intensity under these conditions can be advanced, but the important point is that there is a difference, based upon practical results. Since these reasons may be more or less involved, and may be subject to much discussion, only one will be considered here. It is apparent that two balls hitting together or a ball striking the lining, if there is no intervening material, will produce the maximum sound. If a complete cushion of material is placed between the balls or ball and liner, so that the energy is dissipated without doing useful work, the balls will be unable to create enough pressure or force to fracture the particles, and the sound will be at a minimum. At some point in between-that is, where there is sufficient material between the balls or ball and liner so that the ball will fracture the particles without mashing them unduly-the sound

Jan 1, 1939

By Jos. Van Ackeren

Although the Siemens regenerator principle was introduced into byproduct coke-oven design about 40 years ago, many problems of construction, and particularly of heat distribution and pressure conditions, have not been fully solved. Heat should be applied to the walls of a coke oven in such a way that the coking of the charge of coal will be completed everywhere at the same time, and at approximately the same temperature. This means that the application of heat should be uniform from the top to the bottom of the coal mass (except for the thin layer at the top that is purposely kept at a somewhat lower temperature to reduce cracking of the byproducts); also that a little more heat must be applied to the coke end than to the pusher end, because the coal mass is a little thicker at that end. As a modern coke oven is about 40 ft. long and 12 ft. high, a real problem is involved in the proper application of heat to the oven walls so as to secure quick coking time (without endangering the walls through local overheating) and produce coke made at a uniform temperature. Design of Ovens In all regenerative ovens, the points of combustion are arranged in duplicate sets, one set operating in one-half the area of the heating wall and the other set alternately operating in the other half. Because of the reversal of the flow of gases, the points of maximum and minimum temperatures are alternately located at the same places, thus preventing dangerous local overheating. The practicability of the principle of reversal of flow seems to have been recognized at an early date, and has been applied with every conceivable flue arrangement, combustion chamber, and means of air and gas supply. To summarize the various principles that have proved useful for the control of oven-wall temperature, the best practice seems to have resulted from the acceptance of the use of vertical flues; the separate supply of air and gas to the base of these flues, with the resulting flame

Jan 1, 1923

By James P. Kimball

Sulphur is always present in mineral coal of every variety. In the oxidized state it may exist as sulphuric acid in combination with a base. In the unoxidized state it exists in combination with iron as bisulphide of iron. It is also supposed by some chemists to exist in unknown combinations with the organic elements of the coal. This supposition requires the demonstration as a fact that certain coals yield more sulphur than what may exist in a free state, or what belongs to recognized combinations, not only with the accompanying iron but with other inorganic bases abundantly occurring in coals, but which unfortunately are very rarely estimated. This practically as well as theoretically important question it is at present impossible to decide, simply for want of available thorough ultimate coal analyses including the ash. Such analyses, at the best imperfect, are luborious and intricate, and therefore seldom made, the much simpler proximate analyses, so-called, being resorted to by most chemists for technical purposes, and commonly substituted for more scientific work even in the laboratories of government surveys. And it is unfortunate enough that few ultimate analyses are extended to the composition of the ash, much less to its relation to the original constitution of the coal. Sulphur chiefly occurs in most coals in the form of yellow pyrites (pyrite) and white pyrites (marcasite), both minerals, characterized by differences in crystalline form and in physical properties as well as in color, but having the same chemical composition (FeS2). No coal is entirely free from one or both of these dimorphous forms of bisulphide of iron. It may be disseminated through the mass so as to be invisible, in plates or scales between the laminæ of the coal, or in conspicuous segregations or nodules, sometimes of considerable dimensions. Coals greatly differ as to the proportion of sulphur which they contain. They also differ as to the relative proportion in which its several forms of combination occur. Such qualitative and qnantitative disparities arc scarcely, if at all, more marked in separate coal seams of a uniform type than in different parts of one and the same coal seam, whether it be considered locally as constituted of several

Jan 1, 1880

By James P. Dr. Kimball

SULPHUR is always present in mineral coal of every variety. In the oxidized state it may exist as sulphuric acid in combination with a base. In the unoxidized state it exists in combination with iron as bisulphide of iron. It is also supposed by some chemists to exist in unknown combinations with the organic elements of the coal. This supposition requires the demonstration as a fact that certain coals yield more sulphur than what may exist in a free state, or what belongs to recognized combinations, not only with the accompanying iron but with other inorganic bases abundantly occurring in coals, but which unfortunately are very rarely estimated. This practically as well as theoretically important question it is at present impossible to decide, simply for want of available thorough ultimate coal analyses including the ash. Such analyses, at the best imperfect, are laborious and intricate, and therefore seldom made, the much simpler proximate analyses, so-called, being resorted to by most chemists for technical purposes, and commonly substituted for more scientific work even in the laboratories of government surveys. And it is unfortunate enough that few ultimate analyses are extended to the composition of the ash, much less to its relation to the original constitution of the coal. Sulphur chiefly occurs in most coals in the form of yellow pyrites (pyrite) and white pyrites (marcasite), both minerals, characterized by differences in crystalline form and in physical properties as well as in color, but having the same chemical composition (FeS2). No coal is entirely free from one or both of these dimorphous forms of bisulphide of iron. It may be disseminated through the mass so as to be invisible, in plates or scales between the laminæ of the coal, or in conspicuous segregations or nodules, sometimes of considerable dimensions. Coals greatly differ as to the proportion of sulphur which they contain. They also differ as to the relative proportion in which its several forms of combination occur. Such qualitative and quantitative disparities are scarcely, if at all, more marked in separate coal seams of a uniform type than in different parts of one and the same coal seam, whether it be considered locally as constituted of several

Jan 1, 1880

By Richard W. Smith

Kyanite, long known to occur in Georgia, did not excite coimmercial interest until about 1930. Investigation1 revealed two main types of deposits: (1) separate kyanite crystals embedded in mica schist; and (2) crystal aggregates of kyanite associated with quartz in small and very irregular veins. The second kind at first sight appeared to be the best source of supply. Large boulders or dornicks of kyanite with more or less quartz were found on the surface at many places throughout the Piedmont and Highland sections of the state, but prospecting failed to disclose a sizable vein. These dornicks seem to be a surface accumulation from small veins or lens-shaped masses not more than one or two feet thick, and with a horizontal extent of not more than a few feet. 'rile larger surface accumulation of kyanite dornicks, where not too badly stained by iron oxide, may prove to be marketable, but it is extremely doubtful whether a vein large enough to mine will ever be found. In 1932 deposits of the kyanite-mica schist were known to occur in two places northwest of Clarkesville, in Habersharn County. In 1934, at the request of and in cooperation with the Georgia Geological Survey, the United States Geological Survey made a thorough investigation2 of the deposits and found that the two known areas of kyanite-mica schist in Habershain County were but a part of an unsymmetrical, U-shaped belt (Fig. 1) with a western limb extending into Rabun County and somewhat longer than the eastern limb. The total length of the belt is about 30 miles. The width of outcrop ranges from 100 ft. to 1/4 mile or more. Deposits of kyanite-mica schist of very doubtful commercial importance were found in several other counties. Only the deposits of this kyanitc-mica schist belt in Habersham and Rabun counties will bc discussed in this paper. Geology The kyanite-mica schist of Habersham and Rabun counties occurs near the northern cdge of the Piedmont Upland in metamorphic rocks of pre-Cambrian age3. These rocks probably were deposited as sedimentary

Jan 1, 1938

By Robert Forsyth

As the latest plant on a large scale, the new Bessemer works of the North Chicago Rolling Mill Company, at South Chicago, presents some features of interest to steel-makers, I have ventured to lay before the Institute a short description of that plant, and some* remarks upon the practice there. At the time the South Chicago works were designed the adoption of the basic process in this country seemed imminent. Experience in Europe had demonstrated the perfect success of the process technically, and the question of its commercial value was one which, for any particular works, would have to be settled by its special advantages for procuring the necessary ores and basic materials. Under the circumstances, it was thought best at South Chicago to so arrange the plant as to allow the introdnction of the basic whenever it became advisable, and to make such other changes from the standard type of Bessemer plant as the state of the art seemed to demand and to foreshadow. As the use of metal direct from the blast furnace, while generally condemned by experts here, was in such successful practice in Europe (particularly in connection with the basic process), there was no doubt about its feasibility, while its economy in fuel and labor made it especially attractive to the Western manufacturer. It was accordingly decided to build a direct-metal plant adapted to the basic process. The ingots made were to be rolled into rails at one heat, and were to be of such size (12 inches square and long enough for three and four rails) as to be readily and quickly handled by the rolling machinery proposed. This small size of ingots, and the large number cast from each heat of 10 tons, made it necessary to provide a good deal of room in the casting-pit—much more than in any previons plant—and to put down extra facilities for handling ingots. To meet the delays incident to the basic process—to insure that one vessel should be always blowing if necessary, and to provide opportunity for current repairs to linings, etc.—it was decided that three vessels should be used, and, to properly concentrate the work of

Jan 1, 1884

By A. E. Bellis

There is a wide difference of opinion among rifle experts in the matter of barrel steel, and the relative importance to the life of the barrel of the steel's composition, heat treatment, structure, and physical properties. In order to promote discussion, which it is hoped may' lead to the discovery of the source of some of the traditional beliefs on the subject, the results of some tests are presented here, with data on heat treating, physical tests, and erosion. The detailed metallographic study of this steel is given in another paper.l The conclusions from these tests should be capable of wider application than their direct bearing on the barrel-steel problem. The Government specifications for barrel steel for model 1903 rifle (Springfield) call for carbon 0.50 to 0.60 per cent., manganese 1.00 to 1.29 per cent., silicon under 0.25 per cent., sulfur under 0.06 per cent., phosphorus under 0.08 per cent. The minimum physical requirements are: Tensile strength, 110,000 lb. per sq. in. (7733 kg. per sq. cm.); yield point, 75,000 lb. per sq. in (5472 kg. per sq. cm.); elongation, 20 per cent.; reduction of area, 45 per cent. Material fulfilling these requirements gives practically no failures when proof-fired, with charge of 70,000 lb. per sq. in. pressure, which is 40 per cent. in excess of the service charge. The turning and drilling operations show up any seams or laps such as accidentally occur even in the best heats of open-hearth steel, so that faulty stock is practically all eliminated before proof-firing. These physical requirements are met either by rolling billets at a proper temperature down to the form of tapered barrel blanks or by heat treating bars that have been upset to cnlarge the breech section. The transformation temperature of this steel, on heating, is around 1350" F. (732' C.), varying somewhat with the composition and the rate of heating. The actual treatment of the barrel blanks, as carried out by different manufacturers, gives four kinds of barrels, which will be called A, B, C, and D, for convenience. A barrels result from heat treating upset blanks by quenching at

Jan 1, 1920