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By H. F. Johnson, C. S. Harloff

The Nichols series system of electrolytic copper refining has successfully maintained its strong competitive position in the copper-refining industry of today; therefore the improvements made in accomplishing this result are of interest. While additional interest would lie in specific comparisons of results obtained in series operation with those in multiple, we have refrained from such a comparison because it can be fair to both only when they are operating under similar conditions on the same grade of materials. Historical The Nichols Copper Co. started a small refinery at Laurel Hill, using its present system, about 1892. The details of the process in its early stage of development were kept strictly secret, so that no information was published or interchange of ideas permitted with the staffs of other copper refineries, where the multiple system was being developed at the same time. However, the fundamentals of the process and type of cell used today differ very little from their earliest form. All operations including loading and unloading of tanks, and all transportation as well, were carried on by hand. The plant remained in this condition with a gradual expansion taking place until the World War forced such a rapid development that little time or thought could be devoted to modernization or mechanical improvement requiring careful design or detailed planning. Considerable progress was made, however. (1) Large refining furnaces were developed. (2) The old expensive air-lift type of circulation was abandoned in favor of the present system. (3) Operating technique was gradually developed to a high point of efficiency. (4) Tank construction and lining were greatly improved, the first concrete tank being installed in 1915. (This tank is still in operating condition.) (5) A new power plant was constructed. (6) Fuel oil was substituted for lump coal on the refining furnaces. (7) Mechanical casting of the finished product was accomplished. During this entire period the plant was particularly fortunate in receiving only high-grade, clean copper bullion coming principally from the Phelps Dodge mines in Arizona. This, together with the lack of

Jan 1, 1934

By W. H. Bassett, J. C. Bradley

Beads of metal frequently appear at the ends of cast-copper wire bars and on the sides of wedge cakes near the top. These are richer in cuprous-oxide than the rest of the casting. A micrographical study of these exudations has been made. 11 is suggested that the materical is forced through the surface while the copper is solidifying. If not eliminated in process of manufacture, it shows on the finished polished sheet copper in patches differing in color from the main body of the shad. Figures 1 to 4 show the copper exudations, at different magnifications, as they appear on the ends of cast wire bars, and on the sides, usually near the top, of wedge cakes. Sometimes the exudations are in fine "drops;" at other times, large masses of the material are found. Microscopic examination of the copper exudation indicates that it is high in oxide and of eutectic proportions. Because of the difficulty of securing a suitable sample, the protuberances have not been analyzed chemically; but the spectroscope shows no indication that there are any more metallic impurities present than in the balance of the copper. The lowest copper plus silver content of the coppers studied for this paper was 99.914 per cent.; the highest, 99.966 per cent.; so the oxygen content of the whole casting would be well under 0.07 per cent. Structure of Protuberances The segregation of oxide between grains in the interior of the cast bar, not far from the "set," is shown in Figs. 5 and 6. In general, the amount of cuprous oxide begins to increase at a point about 0.01 in. below the normal surface of the casting, i. e., the base of the drop; but it does not attain maximum concentration in the main body of the metal. Vertical sections, Figs. 7 to 12, show that there is a definite line of large cuprous-oxide globules at the base of the drops. Horizontal sections at this place show that these large globules lie in a thin billowy

Jan 1, 1926

By John Branner

FIVE of the geologic horizons that yield oil in other parts of the world are represented in Brazil; namely, the Devonian, Carboniferous, Permian, Cretaceous, and Tertiary. Thus far, the first two have shown no, evidences of being oil bearing within Brazilian territory. Not enough exploring has been done to permit trustworthy comparisons of the relative importance of the Permian, Cretaceous, and Tertiary as oil-bearing horizons in this country. The most important, indeed almost the only, information available relates to the locations of the areas and to the structural features of the several horizons. The theories regarding the physical conditions under which these rocks were laid down, however, I regard of the utmost importance. PERMIAN Rocks of Permian age cover an enormous area in Brazil, extending from Rio Grande do Sul to Maranhão on the north, and to Matto Grosso on the west. These Permian rocks in many places are known to include oil-bearing shales and in some locations contain small veins of gilsonite. The geologic map of Brazil shows that the Permian area is widely distributed, but there is considerable doubt about 'the origin of some of the rocks:. Some of the lower Permian beds in southern Brazil contain marine fossils, but in Minas no fossils have as yet been found in them, and in Bahia, at only one locality have a few Permian plants been found. Indications of oil have been found in the states of São-Paulo, Paraná, and elsewhere farther south, but wells drilled in the Permian of São Paulo near the Morro do Bofete did not find oil. One well has been started, by the Brazilian government, in the Permian of Paraná near Marechal Mallet, close to latitude 26° south, but thus far oil has not been found.

Jan 6, 1922

By Charles S. Barrett

Metallurgists are making use of the stereographic projection to a steadily increasing extent. In the last five years no less than 20 papers in American metallurgical journals alone have employed the stereographic projection; recent books on physical metallurgy, plastic deformation, X-rays and their applications, and crystal structure use it. Mineralogists have used the stereographic projection for many years in the description of symmetry classes and crystal planes, for it presents an accurate, easily understood plot of any angular relations in crystals with all unessential features eliminated (such as the accidentally determined size and shape of crystal faces). In metallography and physical metallurgy the projection is much used for the analysis of markings appearing on polished grains: slip lines, twins, cracks, structures formed by precipitation, magnetic-powder patterns, etch pits, etc. Data from certain types of X-ray photograms are most conveniently analyzed by its use, particularly those for determining the orientation of single crystals or the preferred orientation of grains in an aggregate. Calculations of how to tilt or cut a crystal parallel to a certain crystallographic plane or to reflect X-rays from a certain plane are rapidly carried out. It has been adopted almost universally to the exclusion of other methods by those studying the deformation of metallic crystals, save where the accuracy required is greater than a few tenths of a degree. Any directional property in a crystal or polycrystalline material can be shown on a stereographic projection; for example, the modulus of elasticity, yield point, etc. It has been repeatedly called to our attention that there is need of an elementary explanation of the principles and methods of stereographic projection, covering all the common applications in the field of metallography and physical metallurgy. The following contribution is an attempt to fill this need. The description of each method is supplemented with references to publications in which the method has been used. For convenience to the reader, these illustrative references are chiefly in American journals, particularly the publications of the American Institute of Mining and

Jan 1, 1937

By R. M. Brick, Arthur Phillips

The Institute of Metals Division Lecture in 1936, given by R. F. Mehl, on diffusion in solid metals1, was introduced with the statement that "the phenomena of diffusion are intimately related to many basic problems of the metallic state, but in addition to this the process of diffusion is of first importance practically." In view of the scope of that lecture, it does not seem necessary to review the importance, history or present status of diffusion problems. One aspect of the subject of diffusion that has received little attention became of some immediate importance in the course of a study on segregation. When a solid solution alloy freezes, the familiar mechanism of solidification requires that the first nuclei formed be low in solute concentration, with a resultant normal segregation or coring effect during freezing. Theoretically, musion of solute atoms during solidification should result in a homogeneous solid solution. Actually, of course, it is impossible in most binary alloys to obtain a cooling rate that will permit diffusion to eliminate coring in the freezing dendrites. For a given alloy, the extent of diffusion attained up to the point of final solidification will determine the degree of enrichment in solute atoms of the final liquid phase. The flow of this liquid into dendritic contraction channels and the solute concentration of the liquid seem to be the determining factors as to whether the final gross segregation is normal, inverse or absent. The purpose of the present study of diffusion was to determine to some extent the separate diffusion rates of copper and magnesium into pure aluminum with a view to clarifying previous results on segregation in these alloys; i.e., the fact that under similar freezing conditions aluminum-copper alloys segregate inversely and aluminum-magnesium alloys segregate normally. Of concomitant interest were the questions of the homogenization times required for segregated ingots or partially melted, i.e., "burnt," structures, and the solution heat-treatment times required for cast, hardenable aluminum-copper and aluminum-magnesium alloys, for worked and annealed structures, and so forth.

Jan 1, 1937

By E. L. Tucker

IN THE metallurgy of precious metals, it has been standard practice for years to use cyanogen compounds, so it was but natural that early investigators in the field of flotation should consider these compounds as possible flotation reagents. In Australian Patent 9508, of 1913, alkali cyanides were described as suitable reagents for the separation of heavy sulfide minerals, the reagents being employed either in an alka-line or neutral circuit. In U. S. Patent 1236501, of 1917, to John M. Tibbet, the use of cyanide in conjunction with soda ash or lime is described. One of the claims of this patent reads, "An improvement in the cyanide process for the treatment of ores comprising, mixing the ore with cyanide solution and oil and alkali: emulsifying the oil in the presence of the ore, the alkali and the cyanide solution, floating a portion of the values in the pulp by producing gas bubbles in the mixture-and removing the values floated." More recently, Sheridan and Griswold, in U. S. Patents 1421585 and 1427235, describe a somewhat similar process and have, successfully introduced it in. the mill of the Timber Butte Milling Co. U. S. Patent 1429544, of 1922, to Stevens, describes the use of double cyanides of copper, zinc, and lead. The success of cyanide as a reagent in the differential flotation of lead and zinc sulfides in highly complex ores is proof that these patents have a solid foundation.. Although the technique of their application to particular ores has been worked out in many cases, no one, so far as is known, has attempted to describe the nature of the action of the cyanide or to determine the ideal conditions for its, application. It was the purpose of the present investigation to gather information on these points. Naturally this would have been an exceedingly ambitious.

Jan 8, 1925

By J. A. Collins

THE process of plastic extension of face-centered cubic single crystal-line rods is so well understood, since the notable studies of Taylor and Elam,1 that the change in orientation of any crystal by slip and rotation may be predicted from the measured elongation. It is customary to assume a very homogeneous deformation, wherein gliding lamellae are free to rotate so that their slip direction continually approaches the axis of the rod, until a second slip system comes into operation; whereupon conjugate slip proceeds quantitatively to an end adjustment with the [112] direction in the axis of the rod. This process has been checked in many face-centered cubic materials and readily permits the preparation of specimens that have been sub-jected to various determinable amounts of shearing action. It is clearly of interest to study in such measurably strained specimens the development of a recrystallized structure on annealing and if possible detect the source of nuclei from which the new crystals grow. Strain-annealing experiments of this character have been performed by others but not in detail sufficient to permit a study, for example, of the number of recrystallized grains vs, the amount of shear. In the experiments now reported, this was done with a wide variety of orientations covering nearly the entire range of slip on a single system and corresponding to amounts of shear (ratio of shearing distance to distance between lamellae) at the conclusion of a test of from 0.08 to 0.57. A particular point was made of determining the crystallite rotation, or small angular range assumed by the octahedral slip plane after these various amounts of shear. The mechanism of recrystallization and the magnitude and effect of recovery on the recrystallization process was investigated.

Jan 1, 1940

By T. Egleston

The necessity of using a refractory material capable of much greater resistance to chemical action and having a far higher melting-point than those which contain silica, which melt and sweat off in the furnace even when not exposed to bases forming with silica more or less fusible compounds, has led to a careful practical study of all those materials which contain very refractory bases. The results of these researches, extending over several years, and made on a very large scale in many of the largest works in Europe, are of the highest interest, not only considered as a step in the progress of the study of the materials themselves, but in the application of refractory materials to metallurgical uses in general. The result of the experience of the last seven years with these basic materials, as in general with all such substanccs, is that natural products cannot be used as such. They are either too uncertain in their quality, contain substances which may in certain cases be very injurious, or, when in a condition in which they might be used, are so rare as to become practically unavailable for employment on a large scale. The materials that may he used are therefore not only limited in number. but they must be prepared artificially. When the use of basic artificial material is further extended, no doubt the number of these substances will not only be greatly increased, but the methods of preparation will be both perfected and cheapened to such an extent as to permit their application in processes for which they have hitherto proved too expensive. The quantity of refractory materials required for making ingots will he from 130 to 150 Ibs. per ton, or between 6 and 8 per cent. of the metal produced. In an establishment producing 2000 to 3000 tons of steel per week, considerable space is required to handle the basic materials properly. It is proposed in this paper to briefly discuss these basic materials and their application in the only two metallurgical processes where they have as yet been applied. These are the basic Bessemer and the basic open-hearth process, known as the Thomas-Gilchrist processes.

Jan 1, 1886

By Lloyd Emory

THE region known as. Guyana or Guiana stretches along the north coast of South America from the mouth of the Orinoco River in Venezuela to the mouth of the Amazon River in Brazil. Politically, it is divided into British, Dutch, and French Guiana, extend¬ ing into Venezuela on the north and into Brazil on the south. Because the area is within the sweep of the northeast trade winds and of approximately the same latitude, plant' and animal life are fairly uniform throughout. The geology is very similar as far as the northern coast is concerned. The drainage is taken care of by a number of large rivers that flow northward directly into the sea. The Courantyne River, which roughly divides the area into half, is the eastern boundary of British Guiana.1 The lower reaches of this river are also the center axis of an ancient bay that at one time indented the coast-line at this point. The old shore-line and, in fact, successive shore-lines can be traced from near the present coast-line in, the northwest district of British-Guiana, south-east and inland, crossing the Essequibo River near Dahli, the Demerara near Christianburg, the Berbice at the mouth of the Kuruduni River and the Courantyne at Vaka-Kuyaha Falls. The line then swings around to the northeast and again approaches the coast near St. Lau-rent in French Guiana. This article will be confined to British Guiana and largely to the valley of the Demerara River, but for geographic names .and topographic details it might, however, apply to Dutch Guiana as well. British Guiana, which comprises about 90,000 sq. mi. and is as large as England, Scotland, and Wales combined, may be divided into three belts, the alluvial belt or coastal plain, the foot-hill area (often spoken of as the sand clay belt), and the hinterland.

Jan 1, 1928

By Robert H. Richards

This is in part a review paper, indicating the various steps that have been taken in developing hindered-settling apparatus, some of the standard data that have been obtained, and some of the conclusions one is led to as to the effect of it in improving concentrating-methods and machinery, and in part it brings in some unpublished work. Causes oF Loss in ORe-ConcEntration. In making a study of the separation of valuable minerals from the waste gangue, particularly by water concentrators, it is necessary to define, first of all, what are the causes of loss that are likely to interfere with the concentration. Having made this definition, we can then study to see in what may the machines make their losses, and plan remedies for them in an intelligent way. Losses may be stated to occur as included grains, as flat or long grains, as fine free mineral, and as absolute slime. We will take these up one by one, as follows: Included Grains.—Fig. 1 shows by a set of diagrams how included grains may occur : first, where the heavy mineral grains attached to the quartz are of large size; secondly, where they are of small size; and thirdly, where very fine particles of heavy mineral are included in the quartz. We have to decide in regard to included grains whether they are rich enough to go direct to the furnace, or poor enough to throw away, or whether they lie between these two points and require recrush-ing as the only means of severing the values from the waste. This last case is the orlly one requiring special treatment at our hands. We will therefore consider that next.

Jan 1, 1911

By Martin E. Chenevert

The early work of Terzaghi1 showed that the true stress state of a rock can be expressed by the principle of effective stress. This principle states that effective stress is equal to total applied stress minus the pore pressure. Since the introduction of this principle, a great effort has been made to measure the pore pressure of rocks so that the true stress state can be determined. For clean, permeable sandstones, it is usually found that the effective stress principle can easily be applied. Direct measurement of the pore pressure is achieved with a hydraulic pressure device and the effective stress state thereby computed. However, for fine-grained rocks which contain large amounts of clay (referred to herein as shales), pore pressure measurements are usually quite difficult because of the adsorptive forces of the clay platelets, which produce negative internal pressures. No suitable device is known for measuring internal pressures of dry shales; the effective stress approach is therefore not feasible and data are usually presented in another form. As an example, data from compressive strength tests are presented as a function of rock wetness, rather than effective confining stress. The work of Belopoloskii2 and Colback and Wiid3 are examples of such data. It was pointed out by Lambe and Whitman4 that a better way must be found to express the effective stress of argillaceous rocks. The information presented herein is an attempt to fill that need. Various authors have been able to measure moderate negative pore pressures (0-240 psi) within rather wet, argillaceous rocks by means of various pore pressure devices. In 1961 Lambe5 resented information which shows that pore pressures in argillaceous rocks are indeed negative ; he presented values of suction pressure as low as - 14 psi. Likewise,

Jan 1, 1970

By Robert C. Linares

Cubic zinc sulfide has been grown from molten salt solutions substantially below the hexagonal-cubic phase transition of 1020°C. Crystals free of birefringence have been grown from molten lead chloride at temperatures from 500° to 800°C. Factors affecting the optical transmission and the birefringence are discussed. CUBIC zinc sulfide is of interest for electrooptic devices and as an optical coating material. However, it cannot readily be produced as large crystals which are free of birefringence. The birefringence arises from the fact that the cubic ZnS is usually grown as the high-temperature hexagonal phase and is transformed to the lower cubic phase by annealing.' This results in stacking faults, stress, and birefringence. A requirement for the growth of cubic ZnS is that it be grown below the phase transition of 1020°C.2 Crystals of cubic ZnS have been grown below 1020°C by the hydrothermal,3 flux,4 and vapor transport5 techniques. However, these all appear to have limitations in size or quality of material produced. It was felt that a new flux method might have a good chance of overcoming some of the previous problems. Mita6 reported the growth of hexagonal ZnS from molten NaCl and wilke7 reported the growth of iron sulfides from molten lead chloride solution, indicating that molten chlorides make good solvents for sulfides. An investigation of a number of possible molten chlorides as solvents showed that molten PbCl2 has an appreciable solubility for zinc sulfide and that crystals can be grown at temperatures from 500° to 800°C. EXPERIMENTAL Crystal growth was performed in open or sealed Vycor or fused silica tubes, in an argon atmosphere or vacuum. There were no deleterious effects due to using vacuum; however, a sealed essentially isothermal system must be used to prevent vapor transport mechanisms from dominating. This will be discussed later in detail. Noble metal containers were not usable as they were severely attacked by these melts. The materials used were: reagent-grade PbC12, reagent-grade ZnS, optical-coating-grade ZnS, and Irtran 2 (ZnS). Crystal growth was accomplished by both slow cooling techniques and gradient growth techniques. In the slow cooling techniques, 15 g of ZnS and 100 g of PbCl2 were used. The components were placed in the silica tube, heated at 800°C for 2 hr, and then slowly cooled (l° to 10° C per hr) to 500°C. The furnace was constructed so that the tube could be inverted, thus allowing the liquid to drain off the crystals at the end of the run. The gradient runs were made by placing the above mixtures in a silica tube at 550° to 600°c, Fig. 1. A temperature gradient was maintained such that the floating mass of undissolved sulfide was 10° to 50°C warmer than the bottom of the tube. Growth occurred on spontaneously nucleated sites at the cooler bottom. RESULTS When using high cooling rates (5° to 10°C per hr), crystals form in thin sheets perpendicular to the {111} face. Crystals 5 by 5 by 1.2 mm, Fig. 2, have been ob-

Jan 1, 1969

By Hugh S. Spence

IN the winter of 1941-42, muscovite mica was discovered by a young prospector, Justin Purdy, in the township of Mattawan, Nipissing District, Ontario, a few miles north of the small settlement of Eau Claire, which lies on the main Transcontinental Highway (No. 17) between Mattawa and North Bay. Muscovite had been known for many years to occur in the general Mattawa region, and various small efforts at production had previously been made by individuals working scattered deposits in the area. These minor activities, however, had never led to production of any consequence or the discovery of any important mica bodies. The Purdy finds were made in a heavily timbered, mountainous area lying about three miles north of the low-lying settled land along the highway, and in a section not hitherto prospected. The mica taken by Purdy and two partners from surface outcrops proved so remarkable in point of size of trimmed sheets that the find attracted considerable attention, and the area surrounding the three claims taken up by the prospectors was quickly blanket-staked by various interests. Though a number of other mica-bearing pegmatite dikes were 'found later on these stakings, none proved as rich as those on the original Purdy ground; very little commercial mica was obtained from them and attempts to develop them were short-lived. Purdy and his partners sold their initial production to dealers in Ottawa and Hull, where the Canadian mica industry long has centered. Young Purdy, unfortunately was killed in a motor accident in the early summer of 1942. His father continued mining operations for a few months and produced and sold a considerable amount of mica. In October 1942 the Purdy holdings were acquired by Inspiration Mining and Development Co. of Amos, Quebec, which had been active in staking in the area. This company formed a subsidiary, Purdy Mica Mines, Limited, to develop the property. Under the energetic management of Joseph R. Norrie, rapid progress was made, and production soon attained important proportions. Realizing from the outset the unusual character and potential value in the war effort of the Purdy discovery, the Metals Controller, Department of Munitions and Supply, at once arranged with the Department of Mines and Resources for an official geological report on the area, and also drew the attention of the War Production Board in Washington to what seemed likely to prove a highly important source of strategic-quality mica. Officials of WPB were sent up in the summer of 1942 to inspect the property,

Jan 1, 1947

By G. H. Clevenger

Continuing the discussion of the paper of James Johnston, presented at the New York meeting, February, 1914. See Trans., xlviii, 3 to 32 (1914). This paper cannot fail of being of great interest and value to all who are interested in the cyanide process, on account of the important developzn~ents which it records. Mr. Johnston is to be commended for the large amount of detail which he gives, and the company and its management for permitting the publication of data of this character, which while of great value to others could well be considered private property. It might be discussed from a number of standpoints: First, as an example of recent practice in mill and cyanide plant construction; second, the mill practice; third, the cyanide practice; and fourth, the new features in cyanide treatment involved. Perhaps a more vivid way of expressing it would be: First, the equipment or tools with which the various operations are carried on, are they the best and most efficient which could have been selected for their respective uses; and, second, is the best use in every case made of these tools? It may be well inquired is the highest possible recovery of silver made at the lowest cost per ounce recovered? For after all, the making of the greatest ultimate profit is inseparably associated with successful metallurgical practice; there must therefore be at all limes a careful balance maintained between recovery and cost of obtaining it. I wish to call attention in a very general way to the equipment used and to an anticipation of questions which are bound to arise in this connection. However, the bulk of my discussion will be confined to the presentation Of certain additional data, together with a more or less general discussion showing the line of development which leads up to the present practice and the applicability of certain features of it to similar problems elsewhere. There are a number of vital points of broad general interest involved in Nipissing low-grade practice upon which metallurgists will by no means be agreed to which I wish to call particular attention in the hope that it will lead to the presentation by others of data of practice in other districts which will assist in reconciling this divergence of opinion.

Jan 1, 1915

By Frederick Laist

THE object of the construction and operation of the 80-ton leaching plant was to test out the leaching of sand tailings on a large scale and, if possible, determine a definite method of operation, and the best construction for the larger unit which is now being built. It was also of importance to obtain some practical data as regards cost items. The 80-ton plant was not expected to be a commercial success. A leaching process on such low-grade material necessitates the treatment of a very large tonnage.. Such a cost item as labor, for instance, is entirely out of proportion in such a small plant. The amounts of acid, salt, scrap iron, and fuel for roasting, however, are the same per ton in an 80-ton plant as in a 2,000-ton plant. These costs were definitely established. Also the percentages of extraction and grade of tailings were definitely determined for a large-sized unit. Following will be found the description of the plant, the method of operation and the results obtained. A -general view of the plant is given in Fig. 1. The bins consisted of one coal bin with a capacity of 30 tons, one salt bin with a capacity of 20 tons, and a "mill tailings" or feed bin which held 70 tons. The coal and salt bins were placed with their floor level even with the firing floor of the roasting furnace. The feed bin, to give it greater capacity, discharged about 12 ft. below this point, to a 12-in. conveyor belt, which, in turn discharged into a pug mill. This fed another conveyor belt, which discharged into the top hearth of the furnace. The furnace was an ordinary six-hearth MacDougall roaster, .20-ft. in diameter. It was equipped with two fire boxes, on opposite sides, the flames entering on the third hearth. An induced draft was obtained with a Buffalo blower, worked as an exhaust fan. Just above the top hearth was an annular flue around the whole circumference of the furnace. Slots at intervals of about 18 in. led from this flue down into the top hearth. The slots were 2 in. wide by 6 in. long. This annular flue proved rather unsatisfactory, as it tended to fill up with flue dust and choke the slots, thus cutting down the draft. The volume of gas through

Jan 8, 1914

Arizona ROBERT W. THOMAS, Chairman 'ROBERT W. HUGHES, Vice-Chairman HUBERT O. WOODS, Secretary-Treasurer American Smelting & Refining Co., Hayden, Ariz. FRANK A, WARDLAW, JR., National Director THOMAS C. CHAPMAN P. D. I. HONEYMAN CARL H. COLE JOHN E. LANNING. JOHN H. DAVIS JOHN C. LOVING EDW. G. DENTZER ALBERT MENDELSOHN MORRIS G. FOWLER BRENT N. RICKARD H. C. HENRIECHARLES F. WILLIS Black Hills BANCROFT GORE, Chairman N. P. GOODRICH, First Vice-Chairman C. N. KRAVIG, Second Vice-Chairman C E. SCHMIDT,

Jan 1, 1941

By Kenneth Seaver

(San Francisco Meeting, September, 1915) INTRODUCTION IT is rather gratifying that in the field of the manufacture 'of refractories, in which, as a whole, foreign practice has surpassed us, the United States stands pre-eminent in the making of silica brick. In some instances European manufacturers have refused point-blank to credit the possibility of making to such specifications as are common with us, until the actual 'completed shapes were shipped for inspection. But both the manufacturer and consumer in foreign lands are now frankly learning from us, and benefiting by our advanced practice in this field, as is evidenced by the orders placed here and the efforts put forth abroad to come up to the standard of American-made material. In no metallurgical operation has the employment of silica brick spread with. such leaps and bounds as in the building of plants for the carbonization of coal, particularly in the byproduct coke oven. Today, in practically all types of oven, the structure above the floor level (except the facings) is of silica, while in the recuperative and in some regenerative types, its use is extended to that portion of the oven below the floor as well. By reason of the fact that there are a number of classes of refractories of higher silica content than the usual so-called fire-clay brick, there is sometimes a misunderstanding as to the class of material referred to as "silica" brick. We here refer only to a brick having a silica content of 94 per cent. or more and made usually from quartzite rock with a small percentage of lime as a binder. The term "silica" brick is sometimes rather loosely applied to brick front highly siliceous clays, or to a quartzite refractory of mingled fire-clay and quartz rock; but such products are not considered in this discussion.

Jan 9, 1915

By George J. Simchuk

Selection of an applicable stripping method and the subsequent determination of appropriate sizes of selected equipment are discussed. The case in point is Utah International, Inc.'s Goonyella mine located in central Queensland, Australia. A detailed study of the various types of stripping methods now practiced throughout the world led to the conclusion that large draglines would be the logical choice for Goonyella. The optimal size of dragline was then determined by first designing a series of cut diagrams using an array of machine and pit geometries followed by a cost comparison of the various sizes of machines, in terms of their effective spoil radius. A dragline with a 51-cu-yd bucket was determined to be of optimum size. Further calculations, incorporating total overburden moved from both the highwall and spoil sides, required that four drag lines, two equipped with 40-cy-yd buckets and two with 54-cu-yd buckets, be used to satisfy the stripping requirements at Goonyella.

Jan 1, 1973

By L. G. Marshall

WHILE surveying in a small Western mine, the following problem was encountered: Two traverses had to be connected by running a traverse line down the main hoisting shaft, which was the only connection between the two levels. The shaft was inclined at about 80 deg. from the horizontal and measured 8 by 10 ft. The distance between levels was about 110 ft., measured on one side of the shaft. The surveying equipment consisted of a transit, tripod, level rod, 100-ft. chain, and plumb bobs. There were no side or top the- scope attachments with which to take large, vertical angles. Therefore, we were confronted with the problem of taking readings between two points, one of which could not be seen through the instrument when set up under the other point, owing to the obstruction of the horizontal plate, and of measuring the distance between these points with a chain that was too short. The method of a line of plumb bobs down the shaft was impractical because a setup would be needed part way down the shaft, which would call a halt to all hoisting operations for some time. After considerable experimentation the following method was used.

Jan 1, 1936

By L. W. Reynolds, R. F. Campbell, K. G. Carroll, S. H. Ballard

Based on metallographic and X-ray data probable equilibrium conditions from 1340" to 2400°F are presented for the composition range investigated. These are correlated with investigations of Takei and Kuo. Provision is made for existence of Mo, C and (Fe, Mo)2,C, carbides heretofore omitted in diagrams in this composition range. These carbides and (Fe, Mo),C, in equilibrium with ferrite and austenite, restrict the austenite and austenite + ferrite fields to lower carbon contents and higher temperatures than in the Fe-C system. OK groups of steel of different molybdenum content, but with approximately the same carbon variation in each group, Table I, were studied. The alloys were melted in an acid-lined 30-lb high-frequency induction furnace, and the ingots forged to l-in. rounds, which were then ground to 0.75-in. diam. To minimize chemical segregations a short length of each bar was given a high-temperature heat treatment as listed in Table I. Specimens 0.062 to 0.125-in. thick were thereafter cut from the homogenized bars for heat treatment to determine phase changes in the alloy. Heat treatments were performed in either a lead bath or muffle-type electric furnace, depending upon the temperature required. Maximum temperature variation was * 2" F in the lead bath and * 5"F up to 1900°F and +8"F above 1900°F in the electric furnace. Adequate protection of the specimen from the oxidizing atmosphere in the electric furnace was obtained by sealing the specimen in either a pyrex or a silica capsule which was evacuated or not as circumstances required. For austenitizing followed by quenching to an isothermal temperature, the specimen was placed in a closed-end refractory tube the mouth of which, extending beyond the furnace, was connected to a vacuum pump. The specimen could be withdrawn from this tube and quenched as desired. IDENTIFICATION OF PHASES The principal method of identification of phases was metallographic examination conducted on surfaces well removed from exposure to lead or atmosphere effects during heat treatment. Hardness measurements (Dph/lOkg) were also made on these surfaces. The etching reagents used and their effects are listed in Table II. Martensite and ferrite were readily recognized by their customary appearance after etching with saturated picral or 1 pct nital. The presence of liquid at high temperature was indicated by curved interfaces characteristic of boundaries between solid and melt, by intergranular pools of dendritic areas in a carbide matrix, and by a black network coincident with austenite grain boundaries. Examples of these structures are shown in Figs. l(a) and (0). The types of carbide which were attacked by the electrolytic chromic acid etch and the alkaline KMnO, etch, Table 11, were identified by X-ray analyses of extracted carbides of five alloys. Carbide residue was obtained from a metallographic specimen by etching the specimen for 24 hr in hydrochloric-picric acid in alcohol (grain-size reagent), after which the carbides, standing in relief, were scraped from the surface of the specimen and mounted on a glass slide. Diffraction patterns were obtained with a Philips spectrometer using iron-filtered cobalt radiation. Figs. 2, 3, 4, and 5 illustrate typical etching behaviors with chromic acid and alkaline KMnO,. Chromic acid attacked Mo,C as shown in Figs. 2(a) and (b)-but not (Fe, Mo),C, Fig. 3(b). Alkaline KMnO, attacked (Fe, Mo),C, Fig. 3(c), and also attacked M0,C. In accordance with these behaviors, a typical differentiation of coexisting Mo,C and (Fe, Mo),~ is shown in Figs. 4(a) and (b). The carbide (Fe, Mo),,C, could not be obtained free of other coexisting carbides for etching experiments. The behavior. however. of coexisting carbides identified by x-ray diffraction as Mo,C ind (Fe, Mo),,C, indicate that (Fe, Mo)23C6 is not etched by chromic

Jan 1, 1961