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By Theo B. Comstock

Since 1892 the writer has published several articles in the Engineering and Mining Journal concerning the relations of the

Jan 1, 1901

THE developments in construction and operation of the basic open-hearth furnace that have taken place in recent years have placed new emphasis on the vital influence played by regulation and control of the combustion system in both furnace production and furnace life. The several factors influencing flame development, such as regulation of fuel supply, air supply, air preheat, furnace draft, and furnace reversal, must be controlled closely if successful furnace performance is to be accomplished. Rugged instrumentation of distinctive design is required to supply dependable information concerning operating conditions, which is requisite to proper regulation of combustion. This chapter attempts to give a practical discussion of the various features of open-hearth practice and instrumentation related to the efficient heating of the furnace, control of temperature, and protection of the furnace structure from accidental overheating. The appended references will be helpful to readers wanting a more detailed treatment of individual topics. OPEN-HEARTH FUELS The most important open-hearth fuels are listed in Table 4-1 together with their compositions and other data useful for combustion calculations. A detailed discussion of open-hearth fuels is not attempted here, but certain factors peculiar to their application to this type of process are briefly indicated on the following pages. Very often an open-hearth shop is forced by economic factors to use a fuel to which its furnaces are not very well adapted, because the general fuel-allocation scheme for the works as a whole seems to demand it. Often a variable marginal supply of coke-oven gas or tar must be consumed by the open hearth, together with another fuel such as producer gas, natural gas, or oil, to fill out total requirements. Most furnaces employ more than one kind of fuel during their usefu1 life; however, the partial redesign

Jan 1, 1951

Jan 1, 1928

By V. L. Elliott, C. L. Meyette

The conditioning of semifinished steel products such as billets, blooms, and slabs to remove surface defects before further processing to finished products is a necessary accompaniment to steel mill rolling operations. A knowledge of the kinds of defects which occur and of the conditions in melting, teeming, and rolling that may lead to their occurrence is favorable to the production of quality products. Surface defects may be classed as either of mechanical origin such as those that occur in the heating and rolling operations and include breaks, tears, guide marks, mechanical laps and the like, or they may have been in the ingot before heating and rolling. Examples of the latter are ingot cracks, blow-holes, scabs, and inclusions which lead to the numerous known types of seams and surface flaws. Most of the common types of surface defects and methods for their identification by visual examination or by the aid of macro-etch tests are well known. The conditions which caused their formation are also appreciably understood and this knowledge has been instrumental in the establishment of methods for metallurgical control. There are, however, defects of doubtful origin. In any endeavor to trace the causes for their occurrence, the question of first concern is: I. Whether they were formed in the rolling procedure. 2. Whether they existed in the ingot prior to rolling. In the case of semifinished products which are rerolled to finished products there is also the question of whether they were formed in the primary or in the secondary rolling. In metallurgical laboratories where numerous or routine examinations of the quality of rolled products are made over the course of time, there will doubtless be many puzzling cases of defect origin. Microscopic examination of the defects may, however, reveal a characterizing condition that can be used to classify them broadly with respect to their origin. Such a condition has been observed and, after detailed investigation, is described here with the thought that it may offer a usable and relatively simple solution to a bothersome problem. Basis For Classifying In this discussion the term "mechanical type defects" will be used to designate those that have occurred as a result of the rolling operations such as in rolling from the ingot to billets, blooms, or slabs or in rerolling to finished products. The term "steel type defects" will be used to designate those that were present in the ingot prior to primary rolling or that were in the semifinished product prior to secondary rolling to finished product. The basis for distinguishing between the two types of defects lies in the relative degree of subscale formation surrounding them. Subscale is defined1 as a zone of

Jan 1, 1949

By V. L. Elliott, C. L. Meyette

The conditioning of semifinished steel products such as billets, blooms, and slabs to remove surface defects before further processing to finished products is a necessary accompaniment to steel mill rolling operations. A knowledge of the kinds of defects which occur and of the conditions in melting, teeming, and rolling that may lead to their occurrence is favorable to the production of quality products. Surface defects may be classed as either of mechanical origin such as those that occur in the heating and rolling operations and include breaks, tears, guide marks, mechanical laps and the like, or they may have been in the ingot before heating and rolling. Examples of the latter are ingot cracks, blow-holes, scabs, and inclusions which lead to the numerous known types of seams and surface flaws. Most of the common types of surface defects and methods for their identification by visual examination or by the aid of macro-etch tests are well known. The conditions which caused their formation are also appreciably understood and this knowledge has been instrumental in the establishment of methods for metallurgical control. There are, however, defects of doubtful origin. In any endeavor to trace the causes for their occurrence, the question of first concern is: I. Whether they were formed in the rolling procedure. 2. Whether they existed in the ingot prior to rolling. In the case of semifinished products which are rerolled to finished products there is also the question of whether they were formed in the primary or in the secondary rolling. In metallurgical laboratories where numerous or routine examinations of the quality of rolled products are made over the course of time, there will doubtless be many puzzling cases of defect origin. Microscopic examination of the defects may, however, reveal a characterizing condition that can be used to classify them broadly with respect to their origin. Such a condition has been observed and, after detailed investigation, is described here with the thought that it may offer a usable and relatively simple solution to a bothersome problem. Basis For Classifying In this discussion the term "mechanical type defects" will be used to designate those that have occurred as a result of the rolling operations such as in rolling from the ingot to billets, blooms, or slabs or in rerolling to finished products. The term "steel type defects" will be used to designate those that were present in the ingot prior to primary rolling or that were in the semifinished product prior to secondary rolling to finished product. The basis for distinguishing between the two types of defects lies in the relative degree of subscale formation surrounding them. Subscale is defined1 as a zone of

Jan 1, 1949

By Charles S. Barrett, Robert F. Mehl, Dana W. Smith

The Widmanstatten figures found in the steels have been long recognized and in some aspects carefully studied,' especially as they occur in cast hypoeutectoid alloys. Aside from the practical importance of the structures obtained in the steels by various heat treatments, a study of the characteristics of these figures is interesting because of the rich opportunity the system affords to obtain new data on the mechanism of segregation from solid solutions. This opportunity is twofold: first, by changing composition within the austenite range the proeutectoid precipitate may be changed from that of ferrite to that of cementite, thus offering the same opportunity for changing the type of precipitate while maintaining the same basic lattice as that afforded by the Cu-Zn alloys;2 and second, the eutectoid inversion leads upon drastic quenching to the formation of martensite, a Widman-statten figure of unique interest from the crystallographic viewpoint, particularly in comparison with those formed on slow cooling.3 We have, therefore, two types of structure to study: that formed on slow cooling of hypoeutectoid and hypereutectoid alloys, and that formed on quenching hypoeutectoid, eutectoid, and hypereutectoid alloys. For each of these types of structure we require the crystallographic plane in the mother austenite along which the precipitate forms (we shall see that the precipitates in these alloys are invariably platelike in form), and also the orientation of the precipitate upon this plane. Some of these

Jan 1, 1933

By Henry Tobelmann

THE location, mode of occurrence of ore, and preliminary tests leading to the development of the present leaching process and the building of the present plant on the property of the New Cornelia Copper Co. at Ajo, have been described in previous papers presented to the Institute and in the, discussions thereof.1 It is sufficient to say that these tests began early in July, 1912, and were continued to the close of January, 1916; that small tests at Douglas were followed by the construction of a 1-ton plant at the mine; and this was followed by the operation of a 40-ton plant for 14 mo. In all about 15,000 T. of ore were treated experiment-.

Jan 2, 1919

By Roland de Wit

Conclusions reached in a paper by weertmanl are amplified in a mathematical and graphical way. It is shown that in a stressed crystal a straight dis-location may be in a position of unstable equilibrium with respect to helix development, and how a small perturbation may start the dislocation off on its helical path. Helix development occurs by diffision; bulk diffusion is necessary for development from a screw, but core diffision is sufficient for development from an edge dislocation. For a mixed dislocation helix development can take place by core diffusion if the helix also climbs; a diffusion reversal takes place when the slope of the helix equals the slope of the Burgers vector. The work done on a crystal by the external forces is graphically shown to be consistent with the direction of motion of the dislocation in helix development. Finally a detailed mechanism for tangle formation from helices is presented. In the course of helix development a glide situation may be reached where a segment of each helix loop lies in a slip plane in which it can expand by glide. Thus is it visualized how a helix can deteriorate into a tangle. A paper by weertmanl proposes dislocation-tangle formation by a helical dislocation mechanism. The present paper amplifies Weertman's arguments in a mathematical and graphical way and presents some further ramifications of the proposed model. The importance of dislocation tangles is discussed in Weertman's paper and the references cited therein. The mechanism of their formation is not yet understood. Weertman proposes that in cold-worked crystals conditions exist suitable for the conversion of straight dislocations into helices and subsequently into tangles. Helix formation occurs by a diffusion process and Weertman proposes that at low temperatures only core diffusion is important. The present paper necessarily repeats some of Weertman's work. Since the mathematical development and notation used are slightly different from his, this was thought necessary for clarity. GEOMETRY OF THE HELIX weertman2 has shown that the equilibrium form of any dislocation line is a helix if it is assumed that the energy per unit length (line tension) of the dis- location is constant. For the special case that no external forces act on the dislocation, the helix reduces to a straight line. We shall assume in this paper that the dislocation has a helical form even when it is not in equilibrium. The parametric equation of a helix is, see Fig. l: where a is the radius of the cylinder tangent to the helix, and 270 the pitch of the helix. The pitch is related to v, the number of turns per unit length (along the axis) by the relation: When a = 0 Eq. [I] gives a straight line in the z direction. The growth of a straight dislocation into a helix is now described mathematically by letting a vary from zero to its final value. The tangent to the helix is given by where is the path length along the helix. This gives the direction of t and since its magnitude is unity we must have So that dcp/ds = (a2 +p2)-"'. The curvature of the helix is given by where n = -(cos + sin) is a unit vector normal to the helix. Note that the vectors k and n always point toward the axis of the helix, Fig. 1. FORCE ON THE HELIX The external force which makes the straight dis-

Jan 1, 1963

By Jr. Baldwin. William M

WELL known to every metallurgist is the fact that different production schedules will profoundly affect the character of annealed metal strip. Yet the number of conditions [ ] that may be wrought by different combinations of rolling and annealing schedules is so myriad that despite the continual research that is being applied to this subject, the complete picture is not yet known. Copper, like all other metals, during the process of rolling or annealing, develops certain crystallographic configurations which should not be dismissed as being too impractical, for the crystallographic condition existing within the metal is a principal influence upon both the external mechanical properties and the behavior of the material [ ] when it is subjected to such operations as bending, flanging, drawing, and so forth. EFFECT OF ROLLING AND ANNEALING UPON THE CRYSTALLOGRAPHY OF COPPER STRIP The most salient points in the crystallographic reactions of polycrystalline copper to rolling and annealing may be best represented graphically by a "map" such as that given in Fig. I. I. As copper strip is cold-rolled from a randomly oriented structure (pole figure I),

Jan 1, 1942

Jan 1, 1889

By George Rice

THE subject of dust explosions in coal mines first appears in the Transactions of this Institute following the first great mine disaster that happened in bituminous mines of the United States. This was the Pocahontas explosion, which occurred Mar. 13, 1884, causing the loss of 112 men. The operating company wisely asked the technical assistance of the Institute, requesting that a committee be appointed to investigate and report. This committee consisted of Messrs. Bramwell, Buck, and Williams, who, after careful study, reached the conclusion that the explosion was due "either to dust alone or to dust quickened by an admixture of fire-clamp too slight for detection by ordinary means." This is perhaps the first time in this country that coal dust was considered to be the chief agency in a mine explosion.. The report is given in the Transactions, vol. xiii, p. 237 (1885). It is particularly worthy of note that the committee called attention to "the necessity of full-sized tests and systematic experiments. " In the same volume of the Transactions, there is a most interesting paper reviewing the literature relating to coal dust, by E. S. Hutchinson, entitled Notes on Coal-Dust in Colliery Explosions. Mr. Hutchinson gives a historical account of observations on the part played by coal dust in mine explosions, beginning with Messrs. Lyell and Faraday's report on the Haswell colliery explosion in 1844, in which it is said "much coal gas had been made from this dust in the very air itself in the mine by the flame of the firedamp, which raised and swept it along, and much of the carbon of the dust remained unburned only from want of air." The subject lay dormant until 1875 when William Galloway began some coal-dust experiments in a small gallery at a mine in South Wales of which he was manager. At that time he considered the presence of firedamp necessary for continued propagation of a dust explosion; but in 1884, the year of the Pocahontas disaster, he stated that no earlier author-than himself had credited coal dust with being a principal factor in mine explosions, relegating firedamp to a secondary place.

Jan 10, 1914

By H. A. Tobelmann

age Introduction ............................. 22 Crushing............................... 25 Leaching............................... 28 .Reduction.............................. 47 Electrolytic Deposition..............a.......... 51 Discard for Purification of Electrolyte.................. 60 Recovery of Copper from Discard Solution .............. 62 Resolution of Cement Copper...................... 64 Summary............................... 64 Appendix............................... 66 Discussion............................... 69 Introduction The location, mode of occurrence of ore, and preliminary tests leading to the development of the present leaching process and the building of the present plant on the property of the New Cornelia Copper Co. at Ajo, have been described in previous papers presented to the Institute and in the discussions thereof.l It is sufficient to say that these tests began early in July, 1912, and were continued to the close of January, 1916; that small tests at Douglas were followed by the construction of a 1-ton plant at the mine; and this was followed by the operation of a 40-ton plant for 11 mo. In all about 15,000 T. of ore were treated experiment-

Jan 1, 1919

By S. W. Miller

DURING the examination of welds made in steel by the oxy-acetylene and electric-arc processes, the writer has met with some unusual structures, which he has not encountered elsewhere. They seem to be quite closely associated with the welding methods used, and characteristic of them, and would seem to be worth noting, especially as the references to them in the literature are few, and their explanation not clear or complete. An introductory word or two about fusion welding may not he out of place. The oxy-acetylene process is based on the great and very local heat generated by the burning of acetylene in the presence of commercially pure oxygen, the two gases being thoroughly mixed before combustion. The theoretical temperature is somewhat under 4000° C., but on account of various losses, the actual maximum temperature is probably about 3000° C. 1 The electric-arc process, using a metal electrode, which is also the filling rod, generates a still higher and more local temperature. The actual temperature of the positive crater of the carbon arc is given as 3500° C.2 No figures have been found for the temperature of the arc using a metal electrode, but it would probably not be very different from that of the carbon arc, and probably higher than that of the oxy-acetylene flame. The greater localization of the electric arc is due to the fact that it is not surrounded by a large envelope flame as well as to its higher temperature; while the oxy-acetylene white cone, or welding flame, in which the carbon of the acetylene is burned to CO, is surrounded and preceded by -a long envelope flame, itself of quite high temperature, in which the CO is burned to C02, and the hydrogen of the acetylene to

Jan 2, 1918

By Willis Burns

I. INTRODUCTION. These notes are submitted, not as a discussion of the modern practice of electrolytic-copper refining, but as the record of a refinery that was among the pioneers in the field and that is to-day, and has been for 17 years, operating under conditions not to be found in any similar plant in the country. I refer to the current density, which is at least 60 per cent. higher than that regularly employed elsewhere, and to the fact that the anodes treated are the direct product of the converter rather than of the reverberatory furnace. The writer has no knowledge of any other refinery treating anodes of this character.

Jan 8, 1913

By Guy Bjorge

IN recent years the Homestake mine has been served by three shafts, the B. &. M., the B. & M. No; 2 and the Ellison, supplemented by an inside shaft, the Milliken, extending from the 2000-ft. level to the 3200-ft. level. In 1932, when a new operating shaft was under consideration, the bottom of the mine was at the 3200-ft. level. The B: & M. and the B. & M. No. 2 shafts were down to the 1550-ft. level and the Ellison was being deepened from the 2600 to the 3200-ft. level. All ore was hoisted at the B. & M. and-Ellison shafts. Levels below the 2600 level, which were under development only, were served by the Milliken shaft. Below the 1550-ft. level, the mine was served only by the Ellison shaft from the surface. Within a few years, when ore reserves above the 1550-ft. level would be depleted, operation would be limited to the Ellison shaft and the auxiliary underground shaft. The Ellison shaft alone was not adequate for hoisting the entire output from the deeper levels and also handling all men and supplies. Further-more, assurance of safety and uninterrupted operation required- two fully equipped shafts to the deeper levels. Therefore a new operating shaft was authorized in November, 1932, and was named for A. J. M. Ross, the mine superintendent.

Jan 1, 1935

By Harry V. Welch

Early in the development of the art of metallurgy, it was noted that a distinct difference existed in the character, collection possibility and health hazard of the "smoke" from lead furnaces and those from copper plants. Zinc-plant fumes, although not so detrimental to health, were closely allied in nature to those of the lead works. In Cottrell plants, there are sufficiently distinct differences in operation and amount of construction between those for lead and copper to justify their consideration under separate headings; therefore, while the application of the process at copper-reduction works was covered by the writer some two years ago in the Transactions1,† this discussion will confine itself more distinctly to "fume" collection. General information on the process has been presented in numerous articles and by many authors: Cottre112, Schmidt3, Bradley4, Anderson6, Labbe6, Shiga7, Rathbun8. "Fume" may be defined as material, metal or nonmetal, elemental or compound, evolved as a vapor from a furnacing or chemical reaction and condensing, chilling or reacting within the gas stream to yield a solid form, and in this definition liquid particles are solids in a sense as distinguished from gases or vapors. Such condensed particles are of minute form, on the order of "smoke," and, for example, on the order of a few hundredths of 1 micron (1 micron = 1/25,000 in.) to perhaps 3 microns, with agglomerates, in relatively small proportions of many particles. Metallurgically typical fume products are lead compounds, oxides, carbonates and sulphates; elemental zinc, more commonly encountered as a fume particle of zinc metal with a surrounding "skin" of zinc oxide; arsenic, both metal and oxide and some of its more complex salts such as added sulphates as found in flue dusts; antimony, more particularly its oxide forms; and elemental sulphur, sometimes a troublesome product, in Dwight-Lloyd sintering-plant fumes. These products, particularly the elemental or lower oxide forms, have relatively appreciable vapor pressures at the existing operating temperatures as reported by Welch and Duschak9, Ingold10, Johnstonll, Millar12,13.

Jan 1, 1937

Jan 1, 1924

Jan 1, 1924

By Donald C. Barton

OF the four papers that comprise this Technical Publication, three are case histories of individual geophysical prospects, subsequently tested by drilling. The bibliography of Dr. Barton's published scientific paperst includes investigations in physiography and surface geological mapping, as well as his geophysical papers, and from this list it is to be observed that he early recognized the place of different types of geophysical prospecting methods in the search for geological structures of economic importance. Moreover, his viewpoint was not merely that the structures should be found, but that the geophysical data should be examined quantitatively to determine the geometry of the structures. In other words, that although these data are insufficient to deduce a unique form for the structure that caused the effects measured in the data, the engineering computations should be carried out to give as much of a definite configuration to the structure as the data permitted, in order that the testing of the structures could be conducted in the most economical manner and with the idea that the experience so gained could be later incorporated in the study of structures subsequently found. Dr. Barton continually emphasized the quantitative use of geophysical observations, whereas at the time that he began his specialization in geophysics it was considered sufficient to use observations only qualitatively. He, more than any one else, was responsible for the first volume on geophysical prospecting issued by the Institute in 1929, and his three articles in that volume stressed the quantitative use of geophysical prospecting. The fourth article in this present Technical Publication is a further contribution to this branch of geophysical interpretation, and is a supplement to the paper in the 1929 volume, "Calculations in the Interpretation of Observations with the Eötvös Torsion Balance." From the successful demonstration by Dr. Barton of the usefulness of quan-

Jan 1, 1946

By Donald C. Barton

OF the four papers that comprise this Technical Publication, three are case histories of individual geophysical prospects, subsequently tested by drilling. The bibliography of Dr. Barton's published scientific paperst includes investigations in physiography and surface geological mapping, as well as his geophysical papers, and from this list it is to be observed that he early recognized the place of different types of geophysical prospecting methods in the search for geological structures of economic importance. Moreover, his viewpoint was not merely that the structures should be found, but that the geophysical data should be examined quantitatively to determine the geometry of the structures. In other words, that although these data are insufficient to deduce a unique form for the structure that caused the effects measured in the data, the engineering computations should be carried out to give as much of a definite configuration to the structure as the data permitted, in order that the testing of the structures could be conducted in the most economical manner and with the idea that the experience so gained could be later incorporated in the study of structures subsequently found. Dr. Barton continually emphasized the quantitative use of geophysical observations, whereas at the time that he began his specialization in geophysics it was considered sufficient to use observations only qualitatively. He, more than any one else, was responsible for the first volume on geophysical prospecting issued by the Institute in 1929, and his three articles in that volume stressed the quantitative use of geophysical prospecting. The fourth article in this present Technical Publication is a further contribution to this branch of geophysical interpretation, and is a supplement to the paper in the 1929 volume, "Calculations in the Interpretation of Observations with the Eötvös Torsion Balance." From the successful demonstration by Dr. Barton of the usefulness of quan-

Jan 1, 1946