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By G. S. Rice

Some form of longwall mining is generally used in Continental Europe; also in Great Britain where the coal is weak and friable, or the coal bed provides material for pack walls and filling, or where the bottom is soft and squeezes up easily, or the roof is pliable, or the bed is thin and brushing provides building material, or the thick multiple seams are mined in layers, such as the 24-ft.seam at Weymss, Scotland, or the 10-yd. pitching bed near Coventry, England. Pillar methods have been retained in British fields where the coal beds are from 5 to 9 ft. (1.5 to 2.7 m.) thick, and free from thick partings or binders or without draw slate, which would provide waste rock for pack walls, or where the roof is hard and requires shooting to bring down, and also the bottom or floor is comparatively hard. The room-and-pillar system, by which probably 95 per cent. of the coal of the United States is produced, is now found in only a few mines in Wales, where it is known as the pillar and (single) stall method. The American room-and-pillar system is not equivalent to the bord-and-pillar or stoop-and-room system. The essential difference between the bord-and-pillar and the average American room-and-pillar system is probably due to natural conditions. The majority of the coal mines in the United States have a depth of less than 700 ft. (213 m.). The bulk of the coal mined in Europe comes from a depth of more than 1200 ft., while the deepest mines in Great Britain, Belgium, and France reach 3500 to 4000 ft. In deep workings wide spans are impracticable, even with the use of abundant timber; accordingly, as the mines in the United States become deeper the rooms will become narrower and the pillars thicker, and the bulk of the coal will be extracted on the retreat. It is generally conceded, without reference to the cost of production, that the larger the pillars left on the first mining, the more thoroughly can the coal be extracted. In Europe complete extraction is generally compelled either by the lessors or by the governments; whereas in this country it has been more largely a question of competitive cost of production, or the support of the surface in the flat farming districts of the

Jan 1, 1922

(Under this heading will be published notes sent to the Secretary of the Institute by members or other persons.) Mine and mill accountant for Mexico. Knowledge of Spanish desirable. Salary $150 to $200 gold per month with living quarters. No. 60. Master mechanic familiar with mine and cyanide plant machinery for Mexico; $200 gold per month and living quarters. No. 61. Electro-metallurgist for production of ferro-alloys, salary $200 to $400 depending on experience. No. 62. Man familiar with ferro-tungsten products of electric furnaces to draw up specifications for machine tools, to watch these tools in service and revise specifications accordingly. Salary $150 to $200 per month. No. 63. Engineers under 35 years of age for placer mining work in Belgian Congo; $1,500 to $1,700 plus traveling and living expenses, two years' contract. No. 67.

Jan 2, 1916

By P. H. Dudley

I HAVE taken the liberty of calling the researches herein mentioned industrial, to distinguish them from those strictly scientific, where every known appliance is used to insure accuracy in determining principles. The industrial researches are made to ascertain wherein we have failed to embody, in practice, the principles which have been fully demonstrated by the more purely scientific investigations. So far the researches have been mostly confined to the conditions of combustion as used in locomotive furnaces, although we have examined, to some extent, furnaces under marine and stationary boilers. The products of complete combustion are gases, and, knowing what we should have, it is at once shown by analyzing the products whether the desired reactions are taking place. In spite of imperfect furnaces, lack of system in the arrangement of grate-bars and exhaust nozzles, the results are not altogether vitiated, because the analyses are not closer than one-tenth of one per cent., as under the present conditions it is hardly possible to collect gas exactly under the same conditions at different times. All of our industrial operations have developed in the past few years so rapidly, nearly all of them paying, that, until within the past three years, comparatively little attention has been given to their economy outside of the profession. Great corporations have not asked and considered the question in earnest, can we utilize our heat so as to produce the same effect at less cost? The applications of heat are so extensive, entering into every branch of industry, the principal power used to carry on metallurgical processes, to conduct transportation, that its economical generation becomes of universal importance; in fact, its economical generation and application is the leading industrial question of the day. It is stated by those who have given the subject much attention, that in our best steam-engines not over 10 per cent of the theoretical value of the fuel is utilized, and upon locomotives it is far less, probably not exceeding under the most favorable circumstances 5 or 6 per cent. In recent experiments made with the dynagraph, in drawing trains upon the Lake Shore and Michigan Southern Railway from Cleveland to Erie, 95i miles, we found the force required to draw a stock train of 709 tons to be 2,498,396,320 foot-pounds, exclusive of the force to move the locomotive itself. We

Jan 1, 1876

By P. H. Dudley

I have taken the liberty of calling the researches herein mentioned industrial, to distinguish them from those strictly scientific, where every known appliance is used to insure accuracy in determining principles. The industrial researches are made to ascertain wherein we have failed to embody, in practice, the principles which have been fully demonstrated by the more purely scientific investigations. So far the researches have been mostly confined to the conditions of combustion as used in locomotive furnaces, although we have examined, to some extent, furnaces under marine and stationary boilers. The products of complete combustion are gases, and, knowing what we should have, it is at once shown by analyzing the products whether the desired reactions are taking place. In spite of imperfect furnaces, lack of system in the arrangement of grate-bars and exhaust nozzles, the results are not altogether vitiated, because the analyses are not closer than one-tenth of one per cent., as under the present conditions it is hardly possible to collect gas exactly under the same conditions at different times. All of 'our industrial operations have developed in the past few years so rapidly, nearly all of them paying, that,, until within the past three years, comparatively little attention has been given to their economy outside of the profession. Great corporations have not asked and considered the question in earnest, can we utilize our heat so as to produce the same effect at less cost? The applications of heat are so extensive, entering into every branch of industry, the principal power used to carry on metallurgical processes, to conduct transportation, that its econonlical generation becomes of universal importance; in fact, its economical generation and application is the leading industrial question of the day. It is stated by those who have given the subject much attention, that in our best steam-engines not over 10 per cent of the theoretical value of the fuel is utilized, and upon locomotives it is far less, probably not exceeding under the most favorable circumstances 5 or 6 per cent. In recent experiments made with the dynagraph, in drawing trains upon the Lake Shore and Michigan Southern Railway from Cleveland to Erie, 941/2 miles, we found the force required to draw a stock train of 709 tons to be 2,498,396,320 footpounds, exclusive of the force to move the locomotive itself. We

By Burt Hartmann

The nation's ever-expanding construction and mining activity has placed an increasing demand upon engineers and geologists to design and construct stable slopes in earth materials-soil and rock. Man's attempt to handle these slope stability problems has been based primarily on practical experience and the resulting theories formulated to explain the phenomena. Too many instances occur when man is faced with a slope stability problem that has not yet been experienced and doesn't lend itself to solution by any existing theory. At this point he must extend himself in using his engineering judgment to arrive at a reasonable and safe design. As past experience has shown, all of the "safe designs" are not really safe. Sometimes they result in embarrassing failures. Measurements provide the key to understanding and controlling natural phenomena. We cannot hope to gain control of the slope stability problem until we understand the causes of slope failure, their behavior with respect to time and their relative magnitudes. Measurements required for an adequate definition of any slope problem must be of the highest reliability because of the importance of decisions which must be based on them. For this reason, direct measurements of movement, shear strength, water pressure, etc. of the unstable mass are preferable to indirect measurements of other physical properties. Movement instruments which can be positioned inside of the slope mass (within boreholes) are among the most useful in diagnosis and/or monitoring of slope movements. The higher the sensitivity and il-measurement precision possible with borehole instruments, the quicker the required information can be obtained and the more exactly may hazardous conditions be observed. A high density of measuring points in a single drill hole is deemed essential for diagnostic purposes. Behavior gradients may thus be obtained. The Pressure Meter (Fig. 1) can be used to measure a relative strength

Jan 1, 1968

By B. M. Larsen, T. E. Brower

An increasing amount of attention is being paid to the possible influence of oxygen, in its several modes of occurrence in steel, upon some of the properties of the metal; but clearly investigations along this line are unlikely to yield significant results until reliable analytical methods for the determination of oxygen have been established. This paper presents some results of a study of an improved Ledebur method which aims to determine a definite portion of the oxygen; namely, that which presumably is present in diffusible form in the solid steel. These more or less preliminary results lead us to believe that the oxygen so determined has some significance; their presentation at this time will, we hope, stimulate discussion of, and focus attention upon, certain rather neglected aspects of the problem. Considerable work has been done recently on methods of estimating inclusions and on the vacuum-fusion method for oxygen; with results which, however, are of somewhat questionable significance. It is commonly presumed that the oxygen in a bath of molten steel in a furnace is present partly as a separate phase consisting of suspended particles of oxides or silicates, partly in solution, the latter being probably the more important. Upon addition of a deoxidizer, it reacts with some portion of the dissolved oxygen and precipitates it as additional suspended particles; the oxygen not eliminated in this way, which remains in solution in the liquid steel, may be regarded indifferently either as dissolved oxygen or as dissolved FeO. When the steel is poured, some of the suspended particles rise towards the surface, others remain trapped in the finished steel, appearing as nonmetallic inclusions in amounts corresponding usually to about 0.01 to 0.03 per cent Oz in the steel. The dissolved oxygen may be partly eliminated as CO during freezing of the ingot, but some remains either in solution or in part precipitated as FeO. Finished steels may thus contain oxygen in several forms: (1) In non-metallic inclusions which are probably quite insoluble in the solid metal at all temperatures; (2) in solid solution which at lower temperatures may be supersaturated; (3) in FeO particles produced by relief of this

Jan 1, 1932

THERE have always been in this world men of such keen intelligence that with their discourse they have been capable of infinite and various inventions that are as beneficial as they are simultaneously harmful to the human body. Wherefore, from day to day, we see unfolded before our eyes some of these that greatly astound our minds, and we remain so stupefied that when-we think of them we are not able to control our faculties for some time, both from considering by what necessity or purpose these men were goaded, as well as from contemplating the profound subtlety of their discoveries, which, in truth, are such that they are awarded the greatest commendation by noble minds. By following their counsels and with their aid, there have been* some astute and lever captains who have had certain pots or balls of earthenware carried by their infantry, expressly filled with compositions of powder or other unctuous liquors disposed to ignite easily. When they meet the enemy in battle and come up close to them, they try to strike vigorously with these in the first assault in an effort to throw them into disorder and to make them give way by breaking them up and drawing them out of formation. The smoke is harmful, but the fire very much more so. These are made in this way. Take the number of vessels that you have to make-it does not matter whether they are raw or baked as long as they are well freed from the moisture of the clay-and fill them a little more than half full with coarse gunpowder which has mixed in it pounded Grecian pitch and at least a third of crushed sulphur. Then pour in a covering a dito thick of strained pig fat mixed with powder. This keeps it from falling out when it is thrown and keeps the fire slower until it reaches the enemy. When this has been made, open up the pig fat a little at one side when you wish to throw it and put in a little fuse or a little good powder and apply fire, holding it in your hand until you see that the fire has taken hold well. Then throw it, choosing your time. A liquid composition is also made in a kettle in which are put pork fat, petroleum oil, oil of sulphur, live sulphur, [163] doubly refined saltpeter,

Jan 1, 1942

By R. A. Perry

A speiss is an artificial arsenide, sometimes an antimonide, formed in lead smelting, smelting of oxide copper ores, and in some lead-refining operations. The production of speiss is closely allied with the amount of arsenic and metallic iron in the blast-furnace charge, while dross is produced mostly from the copper and sulphur, with varying amounts of antimony, arsenic and nickel. Most speiss is essentially an iron arsenide containing some sulphur, copper and nickel, if these elements are present in the furnace. The recent introduction of the soda treatment of lead drosses has produced a speiss high in copper. Speiss is not miscible to any extent with molten copper, lead, matte or slag. Miscibility increases with temperature. This property of the speiss is clarified in the latter part of this paper. Most speisses are produced in conjunction with matte and their sulphur content points to the solubility of matte in speiss. . Some plants have insufficient speiss to warrant separate treatment. When arsenic is high in the blast-furllace charge, there may be sufficient speiss to tap separately from the first settler. Arsenic From the foregoing, it is obvious that a study of the treatment of speiss would not ,be complete without consideration of arsenic. Inasmuch as perhaps go per cent of the blast-furnace feed may be sinter, a definite knowledge of the properties of arsenical ores and compounds that go in to the roaster and sinter feeds is of value. Lcad smelters obtain their arsenic from ores and concentrates, as well as from flue dusts shipped from other plants, particularly copper smelters. The percentage of arsenic in ores is usually low, although occasional lots of high arsenical products are smelted. These crude ores may be sulphides, as arsenopyrite; or oxides like scoiodite, which carry gold or lead minerals. The small amount of arsenic in the original ores received is greatly increased by a circulating load of arsenic in secondary products at are resmelted for their lead or precious metals. More important than the arsenic present directly in the concentrates treated is that in fumes and dusts that may originate in the blast furnace or sinter plant of the lead smelter, or may come from a copper smelter as lead-bearing converter fume or roaster dust. Thus the lead smelter not only must treat its own arsenic but is compelled to handie that from some copper and perhaps other lead plants. Where copper and lead plants exchange products, each plant may be forced to re-treat part of the arsenic it has shipped ,outside its own confines. Speiss from the lead blast furnace contains chiefly iron and arsenic with some lead, copper and sulphur and often appreciable amounts of gold and silver. If its copper content is sufficient this speiss may be sent to the copper smelter where usually it is treated in the converter and the copper is separated as blister. Much of the arsenic and most of the lead are recovered as converter fumes

Jan 1, 1944

By Alexander Squire

A brief study of the effects of material and processing variations upon the tensile properties of steel formed from mixtures of iron and carbon was made in order to provide information regarding the properties obtainable in iron-carbon compacts as influenced by forming pressure, sintering temperature, and graphite particle size. Sintered steels formed from mixtures of iron and graphite have been studied by Stern,' who investigated the effect of various percentages of graphite on compacts formed from electrolytic iron that were repressed and heat-treated after sintering. A further study, by Stern and Greenberg,l is concerned with the heat-treatment of steels formed by the car-burization of iron compacts, and Margolies3 has reported work on the simultaneous sintering and carburization of iron-powder parts. Glauch4 investigated the effect of various types of graphite on the properties of iron-carbon powder alloys but did not determine the effect of different particle sizes of the same graphite alloyed with different types of powder. In the investigation reported in this paper, powders typical of those produced by electrolytic deposition and the decar-burization of shotted steel scrap were used. The powders were mixed by tumbling in a jar mill with graphite powder ground to an average particle diameter of 2, 4, 6, and 16 microns (as determined by microscopic measurement). The properties of the iron and graphite powders are presented in tabular form as Table I. In order to obtain the maximum information from a minimum number of test specimens, the study was divided into two sections with one set of specimens treated identically in each section as a basis for comparison. In the first section, iron powder produced by the shotting and subsequent decarburization of scrap steel was mixed with 2-micron graphite powder, pressed at 50,000, 100,-000, and 200,000 psi, and sintered in hydrogen at 1200°C for the periods of time ranging from 15 to 120 minutes. In the second section of the investigation, electrolytic iron powder was mixed with graphite of an average particle diameter of 2, 4, 6, and 16 microns, pressed at 100,000 psi, and sintered at temperatures ranging from 1000° to r200°C'. for periods of time of 30 to 180 minutes. By following this procedure an indication of the effect of the following variables upon the density and tensile properties of iron-carbon powder compacts was obtained: (I) forming pressure, (2) sintering time, (3) particle size of graphite powder, (4) sintering temperature, (4) type of iron powder.

Jan 1, 1947

By Alexander Squire

A brief study of the effects of material and processing variations upon the tensile properties of steel formed from mixtures of iron and carbon was made in order to provide information regarding the properties obtainable in iron-carbon compacts as influenced by forming pressure, sintering temperature, and graphite particle size. Sintered steels formed from mixtures of iron and graphite have been studied by Stern,' who investigated the effect of various percentages of graphite on compacts formed from electrolytic iron that were repressed and heat-treated after sintering. A further study, by Stern and Greenberg,l is concerned with the heat-treatment of steels formed by the car-burization of iron compacts, and Margolies3 has reported work on the simultaneous sintering and carburization of iron-powder parts. Glauch4 investigated the effect of various types of graphite on the properties of iron-carbon powder alloys but did not determine the effect of different particle sizes of the same graphite alloyed with different types of powder. In the investigation reported in this paper, powders typical of those produced by electrolytic deposition and the decar-burization of shotted steel scrap were used. The powders were mixed by tumbling in a jar mill with graphite powder ground to an average particle diameter of 2, 4, 6, and 16 microns (as determined by microscopic measurement). The properties of the iron and graphite powders are presented in tabular form as Table I. In order to obtain the maximum information from a minimum number of test specimens, the study was divided into two sections with one set of specimens treated identically in each section as a basis for comparison. In the first section, iron powder produced by the shotting and subsequent decarburization of scrap steel was mixed with 2-micron graphite powder, pressed at 50,000, 100,-000, and 200,000 psi, and sintered in hydrogen at 1200°C for the periods of time ranging from 15 to 120 minutes. In the second section of the investigation, electrolytic iron powder was mixed with graphite of an average particle diameter of 2, 4, 6, and 16 microns, pressed at 100,000 psi, and sintered at temperatures ranging from 1000° to r200°C'. for periods of time of 30 to 180 minutes. By following this procedure an indication of the effect of the following variables upon the density and tensile properties of iron-carbon powder compacts was obtained: (I) forming pressure, (2) sintering time, (3) particle size of graphite powder, (4) sintering temperature, (4) type of iron powder.

Jan 1, 1947

By C. Norman Bowers, Blaine B. Wescott

Marked improvement in the serviceability of sucker rods has been effected in the last two years, partly because of the insistent necessity for greater economy in the operating costs of crude oil production growing out of the general industrial depression and partly because many of the recently developed fields have imposed more severe operating conditions upon both surface and underground equipment. The latter is particularly true of Kansas, where practically all of the oil produced is associated with damaging amounts of hydrogen sulfide brine and where the method of establishing potential production demands equipment capable of being operated at maximum capacity without interruptions. The decline of flush production in the Oklahoma City field created new problems in deep-well pumping on a scale heretofore unequaled and the increased proportion of water it has been necessary to produce in the fields of the Greater Seminole area presented conditions that were acutely in need of betterment. The problem in the latter fields was complicated by the shift towards sulfide characteristics, which accompanied water encroachment, and it is probably true that nowhere, at the present time, are pumping conditions generally as severe as in this territory. The Mid-Continent district, therefore, has become the proving ground for the numerous materials that have been proposed for sucker-rod fabrication. The information that ultimately will be obtained from an unprecedented amount of field experimentation will pay ample dividends when the decline of East Texas increases the demand for the vast reserves of sour crude in West Texas. It is a rare occurrence in industry that the use of such a simple piece of equipment as a sucker rod presents so complicated a problem for solution. As proof of this, it is only necessary to consider the numerous types of sucker rods on the market at the present time and contrast this condition with that of less than four years ago, when it was the common aim of manufacturers to develop a single sucker rod for all conditions of

Jan 1, 1935

By Alexander Squire

A BRIEF study of the effects of material and processing variations upon the tensile properties of steel formed from mixtures of iron and carbon was made in order to provide information regarding the .properties obtainable in iron-carbon compacts as influenced by forming pressure, sintering temperature, and graphite particle size. Sintered steels formed from mixtures of iron and graphite have been studied by Stern,1 who investigated the effect of various percentages of graphite on compacts formed from electrolytic iron that were repressed and heat-treated after sintering. A further study, by Stern and Greenberg,2 is concerned with the heat-treatment of steels formed by the carburization of iron compacts, and Margolies3 has reported work on the simultaneous sintering and carburization of iron-powder parts. Glauch4 investigated the effect of various types of graphite on the properties of iron-carbon powder alloys but did not determine the effect of different particle sizes of the same graphite alloyed with different types of powder. In the investigation reported in this paper, powders typical of those produced by electrolytic deposition and the decarburization of shotted steel scrap were used. The powders were mixed by tumbling in a jar mill with graphite powder ground to an average particle diameter of 2, 4, 6, and 16 microns (as determined by microscopic measurement). The properties of the iron and graphite powders are presented in tabular form as Table I. In order to obtain the maximum information from a minimum number of test specimens, the study was divided into two sections with one set of specimens treated identically in each section as a basis for comparison. In the first section, iron powder produced by the shotting and subsequent decarburization of scrap steel was mixed with 2-micron graphite powder, pressed at 50,000, 100,000, and 200,000 psi, and sintered in hydrogen at 1200°C for the periods of time ranging from 15 to 120 minutes. In the second section of the investigation, electrolytic iron powder was mixed with graphite of an average particle diameter of 2, 4, 6, and i6 microns, pressed at 100,000 psi, and sintered at temperatures ranging from 1000° to 1200°C. for periods of time of 30 to 180 minutes. By following this procedure an indication of the effect of the following variables upon the density and tensile properties of iron-carbon powder compacts was obtained: (I) forming pressure, (2) sintering time, (3) particle size of graphite powder, (4) sintering temperature, (4) type of iron powder.

Jan 1, 1947

By G. S. Rice

With so tremendous a subject, an attempted review of the coal situation of the world in a short talk must necessarily be of a sketchy character. It is hardly necessary to tell a body of engineers that had it not been for nature's gift of coal the material side of modern civilization would never have reached its present status. On the other side, it is regrettable that it was a byproduct of coal, T. N. T., which made possible Germany's initial success in this war, because that country had an enormous development of manufacturing plants that could be immediately utilized to make this destructive agent: One sometimes hears the casual remark that when the coal of the world is exhausted we shall use electricity; but, of course, electricity is ordinarily only a means of transforming and transmitting energy derived from fuel or water power, and chiefly from coal. It is true, we have much undeveloped water power, but it is more or less remote from 'the, centers of industry; and when all shall have been developed it will not begin to supply the power requirements of the world. It is, however, reasonable to expect that before the world's supply of coal shall be exhausted, methods will have been discovered of harnessing other forces of nature, such as the tides, or the energy emanating from the sun. Petroleum and natural gas naturally come to mind, but the days of both, as fuel, appear to be numbered, although the products of petroleum, if economically used, doubtless will be available for internal-combustion engines, automobiles, trucks, and boats for a long time, provided the reckless use of crude petroleum as an ordinary fuel is stopped. The products of petroleum are too valuable to mankind for such waste to be permitted. The civilization of the world, therefore, appears to rest, and, so far as can be seen, will indefinitely continue to rest, upon coal. COal Resources of the World According to the compilation made by the geologists of the principal countries for the 12th International Geologic Congress, held in Canada

Jan 1, 1918

By O. W. Ellis

RECENTLY there has been a considerable revival of interest in the effects of the various elements commonly added to brass for the purpose of increasing its strength. For many years the work of Guillet2? alone gave reliable information in this regard. Even today his determination's of the coefficients of equivalence of the various elements relative to zinc in brass are those universally employed in industry. This is so because these coefficients have stood the test of time-their substantial correctness has been proved in almost universal practice. It is not our intention to discuss here these coefficients or their use. Rather do we wish to emphasize the need for further systematic studies of the mechanical properties of the ternary systems of copper, zinc, and other individual elements. Since Guillet published the results of his first investigations Millington,16 Smalley33 and Thibaud45 have added somewhat to our information. In general they have confirmed the findings of Guillet, which may be stated in the following rather general terms: 1. The addition of aluminum to the 70:30 and 60:40 brasses progressively increases their hardness and strength and reduces their ductility and resistance to shock. 2. The addition of small amounts of iron to a 60:40 brass improves its strength without affecting its ductility. 3. The addition of small amounts of manganese to a 60:40 brass causes a progressive increase in its strength and reduction in its ductility. A considerable amount of information has been amassed in regard to the effect of nickel on brass (9, 22, 41) which it is unnecessary to refer to here, in view of the scope of this paper.

Jan 1, 1929

By R. J. Stevens

The Roan Antelope Smelter commenced operations in October, 1931. As originally designed, its equipment consisted of one reverberatory furnace, 120 X 25 ft, two Peirce-Smith converters 12 X 20 ft, and one straight line casting machine. Since that time the following additions have been made: One reverberatory furnace 120 ft X 28 ft ('934) One reverberatory furnace 95 ft X 28 ft (1943) Two 12 X 20 ft Peirce-Smith converters (1934 and 1938) One 13 X 30 ft holding furnace (1938) One straight line casting machine and 2 ladle tilting quadrants (1934) The metallurgy of the smelting process is comparatively simple. However, there are several features of operation which are uncommon to most copper smelters: (I) The high grade of concentrate treated; this has always been about 50 pct copper. (2) The high flux burden on the charge. This is necessary because of the deficiency of bases in the concentrate and the high alumina content of the concentrate. (3) The frequent necessity of adding coal to the furnace charge to control the matte grade. (4) The high grade of matte produced. This has led to unusual converter problems. From the commencement of operations, the ore mined has come from the Roan Basin orebody. The concentrate produced from this ore consists mainly of chalcocite and shale with small proportions of other copper minerals. As mining operations extend to the Roan Extension orebody, the proportions of bornite and chalcopyrite in the concentrate will increase with a corresponding decrease in the copper content of the concentrate. Because of the concentrate grade the capacity of the reverberatory furnaces in terms of tons of copper produced per ton of coal burned is high. This ratio is usually over 2.2, and on especially favourable runs has reached 2.6. Reference to Table I shows that the iron content of the concentrate is unusually low. Only part of this iron is available for slag formation, the balance going to the matte. To make up this deficiency in bases, limerock is added to the furnace charge. This flux ensures a slag that is of the correct silicate degree, is suficiently fluid, of low specific gravity, and it counteracts the thickening effect of the alumina present. An ample supply of flux is obtainable from Ndola, 22 miles distant by rail. Although the reverberatory slag has a high copper content, the slag fall is low and the copper loss in the slag now rarely exceeds 1.0 pct of the total copper charged. The blister copper shipped is of such purity that only one fire refining operation has been necessary to produce a wirebar with properties comparable to electrolytic copper. Bismuth has always been the most troublesome impurity and consequently the problem of its control in the finished product has been of prime importance. Practically none is removed in the reverberatory furnace. The bulk of the elimina-

Jan 1, 1949

By Albert J. Phillips

IT is a privilege and a pleasure to deliver this, the Twenty-sixth Annual Institute of Metals Division Lecture. Eleven years ago C. A. Edwards addressed this audience on the subject "Gases in Metals." In spite of this relatively recent presentation, I propose to, present to you some quantitative considerations of industrial significance on the separation of gases from molten metals because recent observations and measurements, presented in the literature, have made it possible to evaluate mathematically the gases or gas-forming elements and to develop an understanding of the mechanism of gas separation that should permit, in many cases, the control of this baffling phenomenon. DEFINITIONS Before becoming involved in the subject it seems desirable, for the sake of clarity, to state certain definitions and axioms: I. We are dealing only with gases that separate from the molten metal either during cooling or in the transition from liquid to solid. Gases injected by the liquid stream and trapped in the solidified metal, or those forced into the solidifying metal from the mold due to either thermal or cher4ical effects are not considered. Neither are we concerned with the separation of gases within the metal after solidification is complete for the data on this subject are at least complete enough to permit the practicing metallurgist to satisfactorily control the phenomenon. 2. Only where there is a decrease in solubility or a change in equilibrium of either a gaseous element or an element that reacts to form a gaseous compound, can there be a separation of a gaseous phase from the liquid or solidifying metal. 3. The amount of gas separating from the liquid during solidification can be computed directly from the amount of the element contained in the liquid when freezing commences less the amount of the element found in the solid either as a separate solid phase or in solid solution. 4. There can be no separation of gas bubbles unless the told pressure of the gases in the liquid meld exceeds atmospheric pressure plus the hydrostatic pressure of ' the liquid metal head. (In addition, pres- sure resulting from surface tension in- creases the total pressure requirement for initial gas separation. Probably the remarkable differences in appearance caused by different gases in the same host metal are influenced greatly by the rate of diffusion of the gas in the liquid metal balancing the decrease in pressure as the gas bubble size increases and the surface tension effect decreases. Thus hydrogen with its high diffusion rate in liquid copper separates in the form of relatively coarse cavities for a given rate of heat extraction.) 5. Gas separation can take place at less than atmospheric pressure in the voids created by the shrinkage from liquid to solid, but since the voids are not caused by the gas the presence of gas in the voids is of importance only where it

Jan 1, 1947

By J. B. Scuffham, G. A. Rowden

The use of ammonia as a leaching agent has been well-documented but only recently have its advantages been fully exploited on a commercial basis. When compared with conventional sulfuric acid leaching processes, the major advantage of ammoniacal systems is their ability to reject iron and many acid consuming gangue materials. Although metallic copper, nickel, zinc, etc. are dissolved rapidly in ammoniacal liquors at ambient temperature in the presence of air the sulfide ores of these metals are more resistant to this treatment. Sherritt Gordon Mines in Canada treats sulfide concentrates at its Fort Saskatchewan plant under pressure with ammoniacal am- monium sulfate solution to solubilize the non-ferrous metal values. Typical leach operating conditions are 80-95°C and 115- 128 psig. Although the metals present in the ammonical solution could be recovered via solvent extraction techniques, Sherritt Gordon Mines currently operates a pressure reduction process using hydrogen to yield metal powders directly from the ammoniacal solution. The basic Sherritt Gordon technology has been applied world wide for the treatment of nickel/cobalt concentrates.

Jan 12, 1973

By F. L. Vogel

Densities and distributions of dislocations in plastically bent germanium crystals before and after annealing were studied. In the bent and annealed crystals, the theoretical relationship between radius of curvature and density of dislocations is confirmed. Before annealing, however, more dislocations are present than required, and these are distributed with a minimum at the neutral axis and maxima at the top and bottom surfaces. On annealing, three significant changes occur in the bent bars: 1) the average dislocation density is reduced, presumably by the annihilation of opposite signs; 2) dislocations migrate from the high density outside regions toward the low density neutral axis, thus producing the equilibrium distribution of dislocations; and 3) a polygonized structure is formed by movement of the dislocations into walls normal to the slip plane. ETCHING to reveal edge dislocations'-" offers a unique opportunity to study, in germanium single crystals, the functioning of dislocations in plastic deformation. Plastic bending is ideally suited to this purpose because it produces a static array of edge dislocations in an ideally plastic material which is predictable from the theory." " Nye" has given a rather complete treatment of the geometry of bent crystals in terms of dislocations. The density of excess dislocations is related to the radius of curvature of the slip plane of a bent crystal, as shown in Fig. 1, assuming the absence of macroscopic elastic stresses. The curvature of any plane in the zone of the bend axis is found by resolving the Burgers vector into that plane, so that for the usual case where the slip plane is inclined at some angle 0 to the neutral plane of the bar, the equation applies, with T equal to the radius of curvature of the neutral plane of the bent crystal. Two predictions which are relevant to this study may be made from Eq. 1. First, in crystals bent to various radii, the average excess dislocation density is inversely proportional to the radius and second, for a bar bent to a radius which is large compared with its thick-

Jan 1, 1957

By E. D. Gardner

Introduction Oil shale deposits have been exploited in various countries throughout the world, but generally with government aid. The oil-shale industry of Scotland perhaps is the oldest and best-known; the largest was conducted in Manchuria by the Japanese during World war 11 as a source of liquid fuels for military uses. In general, foreign oil-shale deposits that have been exploited are much lower grade than those in the western United States. Considerable interest began to be shown in western oil shales in 1916; the peak of activities was in 1923. The catlin operation, near Elko, Nevada, perhaps was the nearest approach in this country to an oil-shale enterprise on a commercial scale. Over 100 companies were formed, ostensibly for exploiting the oil shale; a large number of them, however, proved to be stock promotions only, which gave the embryo industry a black eye. The Bureau of Mines operated an experi-mental oil-shale retort plant near Rifle, Colorado, from September 1926 to June 1927 and again from April 1928 to July 1929, after which the plant was dismantled. By this time the East Texas oil fields had come ill and the country lost interest in substitute liquid fuels. During World War II the Nation again became concerned about the magnitude of its petroleum reserves. Congress (April 1944) directed the Bureau of Mines to build and operate demonstration plants to produce synthetic liquid fuels from coal, oil shales, and agricultural and other products; a five-year Program was authorized. *' a part of this program the Bureau of Mines has built, at Anvil Points near Rifle, Colorado, a retort plant and develOped an experimental mine to supply the plant with oil shale. An important part of the mining work at Rifle is to devise methods and select practices for mining the oil shale on a commercial scale at the lowest practicable cost. The product to be mined has a relatively low value, a fact that must be kept in in mind. The combined aim of those in charge of the mining and those in charge of retorting is to demonstrate that the shale oil can be produced at a cost per barrel corresponding to the current quotation for crude petroleum —or at least very close to it. Plans call for an uninterrupted flow of broken oil shale from the lace in the mine, through crushers, through the retorts and thence to the disposal dump. The disposal of the spent shale in the Ride area should present no unusual problem. Mining research has consisted so far of Paper studies of the general phases of the probleml determination of the widest Span that the roof Stone will stand safely unsupported, and drilling problems. underground development has not proceeded far

Jan 1, 1949

By R. W. Fenn, H. A. Lepper, W. R. Hibbard

THIS paper reports the results of static tension and torsion tests made on single crystals of alpha brass for the purpose of determining its elastic coefficients. 70-30 alpha brass was chosen because it has been used extensively in the study of the plastic deformation and because it has the following desirable characteristics: (1) face-centered cubic structure, (2) marked elastic anistropy, (3) low elastic modulus. In 1928 Masima and Sachs' using static methods reported the following values for the elastic coefficients of 72-28 pct alpha brass: S11 = 19.4 X 10-13' cm2 per dyne S12 = —8.35 X 10"' cm2 per dyne S44 = 13.9 X 10-13= cm2 per dyne These values were obtained from the measurements shown in fig. 1. The experimental points for both tension and torsion lie consistently below the lines drawn to represent them. Fig. 2 shows the stress-strain curves for their specimens. Only a few points in the elastic range of these curves were available to obtain their values for Young's modulus. Therefore, it was considered that a re-evaluation of these data was desirable. In addition a variation of from 1.13 to 1.485 kg per mm2 was found in the values of the critical resolved shear stress for 70-30 alpha brass reported by Burghoff,² Treuting and Brick: Martin,4 Maddin, Mathewson and Hibbard5,6 and von Goler and Sachs.' Therefore, it was desired to evaluate the conclusion of Boas and Schmid8 that a constant resolved shear stress and not a constant elastic shear initiates plastic deformation. Theoretical Considerations*: The elastic deformation of cubic crystals may be defined by three elastic coefficients (S11, S12, S44,) or three elastic parameters (C,,, C,, C,,). These coefficients or parameters are sufficient to define the stress and strain relations for cubic crystals in the generalized form of Hooke's law referred to Cartesian coordinates. Elastic parameters and coefficients in the cubic system are related by the expressions: C11 —S11+S12/(S11-S12)(S11+2 S12) C12=-S12/(S11-S12)(S11+ 2 S12) (S11 — S12) (S11 + 2 S12) [2] C44 =1/S44 PI It is possible to determine all the elastic coefficients for a cubic metal by measuring two of the three elastic constants: Young's modulus (E), torsion modulus (G), or compressibility (S). The following relations exist between crystallographic orientation and E, G and S for cylindrical crystals of the cubic system: 1/E = S11 — 2 [(S11 - S12) — Su] (?1² ?2² + ?2²?83 + ?3² ?1²) [4]

Jan 1, 1951