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ALTHOUGH the refining period of the heat is generally defined A as starting after the charge has been completely melted, it may more properly be considered as beginning with the first efforts to facilitate the shaping up of the slag and the making of corrective additions for the control of slag or metal composition. Such actions may be initiated during the latter half of the lime boil. The early part of the refining period may, then, in essence overlap the latter part of the melting period. The primary aims of the refining period are: (1) to reduce phosphorus and sulfur from the steel bath to levels safely below the maximum contents specified; (2) to eliminate carbon to a specified level as rapidly as possible and still allow time for proper conditioning of the slag and attainment of the necessary bath temperature; and (3) to have the heat ready for tapping or furnace deoxidation, with slag in the proper physical and chemical condition, and with carbon and oxygen contents and the temperature of the steel at the proper levels for the composition and grade of steel being produced. The particular conditions that fulfill these aims are distinctly different, depending upon whether the steel is to be finished according to fully killed semikilled, or rimming practice and also depending upon the carbon range specified. Regardless of the type of charging practice employed, the object of the refining period is to produce repeatedly the desired finishing and tapping conditions for the grade of steel being produced. The variations and proportions of raw materials used in the charge may cause some variations in the degree of control required during refining, but not in the method of control. The refining period can therefore be discussed from a viewpoint largely independent of charging and melting practice. SHAPING UP THE SLAG In the first helper's vocabulary, refining practice consists in

Jan 1, 1964

By F. L. Toy, C. E. Sims

PNEUMATIC processes for converting molten pig iron to steel were the major producers of steel during the latter half of the 19th Century and until shortly after the turn of the century, when these processes began losing ground to their rival—the basic open hearth process. The first pneumatic process for converting molten pig iron to steel was introduced almost simultaneously by Sir Henry Bessemer in England and by William Kelley in the United States during the decade 1850-1860, but it was Bessemer who pushed it to a successful commercial operation. The process itself is so basically simple that it has not lent itself to many extensive or revolutionary improvements since its inception. During the first 30 yr, numerous' designs of vessel and many modifications of practice were tried before the industry standardized on something resembling current practice. The evolution in construction has resulted in proportions and arrangements based more on mechanical expedience than on metallurgical requirements. Many of the early converters were stationary and had to be tapped similarly to the cupola or open hearth furnace. Such types were used for many years in Sweden and Germany, but the rotating or tilting types were favored in England and the United States. There was evident trouble with bottom tuyeres, becAuse about half of the early designs were constructed for side blowing with tuyeres submerged below the metal-bath surface. Even portable tuyeres, introduced from above, were tried. The principal advance, which made bottom blowing practical, was the invention, in 1863, by Henry Bessemer, and subsequent improvement by A. L. Holley, of a detachable bottom so that the tuyere section could be renewed. In the meantime, it was the demonstration, by Robert Mushet, of the value of manganese in overcoming hot-shortness in converter steel, that made the process metallurgically feasible. At first, only the acid practice was used, and Swedish pig iron, because of its low sulphur and phosphorus, was in great demand. The development of a suitable basic lining, by Sidney G. Thomas and Percy G. Gilchrist in 1876-1879, made the process applicable to the high-phosphorus ores of Europe. From the beginning of the use of the Thomas-Gilchrist process, trouble was experienced in obtaining sufficiently high temperatures in the blown metal, particularly in small heats. It is necessary, of course, to have the low-carbon blown metal at a considerably higher temperature for handling from vessel to ladle to molds than is needed for the molten pig iron. All of the increase in temperature in a pneumatic process must be obtained from the heat of combustion of the elements contained in the pig iron plus that from silicon when ferrosilicon is added. In bottom blowing practice, carbon is almost completely burned, but inasmuch as it cannot be oxidized to a higher state of oxidation than to CO when in contact with liquid iron, only a minor portion of the heat-producing capacity is utilized. Under such conditions, it is not considered to be an efficient source of heat. In the acid practice, therefore, silicon and manganese are the large heat producers, are quickly oxidized, and are efficient fuels. Too much manganese, however, thins the slag greatly and tends to promote excessive slopping or throwing of slag and metal from the converter during the blow. Most operators, therefore, like to keep the manganese content of the iron below 0.60 pct, and thus the main source of heat is the silicon, which must be at least 1 pct and sometimes 2 to 3 pct for small blows such as for castings. Ferrosilicon is sometimes added during the blow to obtain an adequate temperature level. In the basic (Thomas) practice, even more heat is required, because cold lime is added to flux the phosphorus after it is oxidized, and the basic slag must be maintained at a proper temperature. Silicon

Jan 1, 1951

By Hans Lundberg

FOR the last 20 years, geophysical methods have been in practical use. The results accumulated during this time have been broad enough to enable us to formulate some general rules for conducting geophysical surveys to the best advantage. It is a well established fact that electrical and magnetic methods have aided the geologist to outline bodies of ore, to differentiate between various types of rocks hidden from view and also to determine the thick-ness of the layer of drift that covers the bedrock. Fundamental require-ments for a successful solution of a geophysical problem is the existence of physical differences between the various formations under investiga-tion. If such conditions exist, our problem becomes a physical, mathe-matical and geological analysis of the effects of these differences upon the structure of an arbitrarily produced, or already existing, field of force. Experience has shown that reliable and consistent results in analyzing such fields of force are obtained only if: (1) the methods and apparatus used are scientifically sound and designed to provide information with a maximum amount of accuracy, reliability, sensitivity, simplicity and speed of operation, and (2) the interpretation of the results of such an investigation is guided not only by rigid mathematical rules but also by common sense, based upon sound geological knowledge and imagination. Today, a number of methods are based upon sound principles, are highly sensitive and are well suited for field work. The instrumental developments have resulted in self-contained instruments, which permit the determination of field ratios and intensities with great accuracy. Magnetic surveys have almost become standardized. The electrical methods, mostly based on the determination of potential-drop ratios, or electromagnetic field ratios, are built as bridge circuits and it is easy to determine amplitude, as well as phase relationship of the various electrical and electromagnetic fields.

Jan 1, 1938

By L. B. Gittinger

Sulfur is a nonmetallic element widely distributed in nature. It constitutes 0.06% of the earth's crust but only a very small portion occurs in sufficiently concentrated amounts to justify mining. Sulfur occurs in practically all animal and plant life. It constitutes approximately 0.09% of the elements in the oceans; it has been found in meteorites. Sulfur was known and used by man before recorded history. The American Chemical Society approved spelling for the element is sulfur. The English spelling sulphur is used commercially in the United States. In ancient times, sulfur was called brimstone, literally "burning stone." Today the term brimstone is used interchangeably with the term elemental sulfur. Sulfur is found naturally in the elemental form in subsurface deposits associated with gypsum and anhydrite in salt domes and sedimentary formations in evaporite basins and in solfatara-type deposits associated with volcanoes and mineral springs. Sulfur occurs also in molecular combination in ferrous sulfides (pyrites and pyrrhotite) and nonferrous sulfides (copper, lead, zinc, and nickel), and in mineral sulfates (gypsum and anhydrite); as hydrogen sulfide contaminant in natural gas; as organic compounds in crude oil and tar sands; and as pyrite and organic compounds in coal and oil shales. Sulfur resources are abundant and exist throughout the world but the extent to which they can be classified as reserves is greatly circumscribed by prevailing prices and technology. Estimates of world sulfur reserves are compiled by the U.S. Bureau of Mines. A compilation of reserves by area and source of sulfur published in 1970 and presented here as [Table 1] totaled 2.47 billion tons (Lewis, 1970). The effect of the decline in prices which has occurred since the earlier estimate is dramatically illustrated by the 1972 estimate of the U.S. Dept. of the Interior which shows world sulfur reserves of only 1.2 billion tons (Anon., 1972d). Sulfur is produced commercially from one or more sources in nearly 70 countries of the world. World production of sulfur in all forms totaled 41.6 million tons in 1971. (Sulfur statistics given in this chapter are long tons.) Native deposits, sulfides and oil and gas contributed, respectively, 31, 41, and 25% of world production (Table 2). Of the sulfur produced from native deposits, salt domes accounted for 54% and evaporite basin deposits, 44%. Volcanic deposits are of little significance except for local consumption. The past two decades have seen important shifts in the world's sulfur sources. In 1950, native deposits and sulfides each supplied about one-half of the world's production. During the 1950s, sulfur recovered from oil and natural gas grew rapidly, representing about 10% of the total by 1960. Since then, the petroleum industry has continued to increase its relative importance as a source of sulfur, representing more than 30% at 1972 year-end. Sulfur is generally classified as elemental or nonelemental for statistical purposes. Elemental sulfur is sulfur produced in the pure, uncombined form. It includes production from native deposits, as well as that recovered in the elemental form from oil and natural gas or other sulfur-bearing materials. When produced from other than native deposits, it is generally referred to as recovered elemental sulfur. Nonelemental sulfur is that which is utilized commercially in molecular combination with other elements, such as sulfides or sulfates. Elemental sulfur is being produced from salt dome deposits in the Gulf Coast region of the United States and the Isthmus of Tehuantepec in Mexico, and from evaporite basin deposits in west Texas, Poland, Sicily,

Jan 1, 1975

By R. E. Barnes

An overall view of the perlite industry is concisely presented. The geology, mining, milling, processing, and applications of perlite, as well as the present status of the perlite industry are treated. Perlite, in strict petrological usage, describes a specific variety of volcanic glass in which strain, incident to cooling, yielded a concentric structure of fracturing which may be visible either to the naked eye or under a microscope. In commercial usage, the term perlite includes any naturally occurring acidic glass of volcanic origin that will expand when heated to a suitable temperature. The name perlite is a derivation of perlstein which originally defined "certain glassy rocks (hyaloliparites, hyalo-rhyolites) with numerous concentric cracks, from the fancied resemblance of broken out fragments to pearls."1 While perlite has been known to geologists for many years, it was not until 1941, while investigating perlite for use in enamel, that an assayer in Superior, Ariz., noted the unusual expansion characteristics of the ore. Further investigations were delayed until following World War II when many small plants were built and experimentation in the treatment and uses of perlite began. The Perlite Inst. was organized in 1949 to promote the development of the new industry, establish commercial standards through research, and to explore new uses and markets. The Institute, located in New York, represents some 50 producers in the U.S., Canada, Australia, England, France, Germany, Greece, Japan, Mexico, and New Zealand. In 1949, 71,l002 short tons of crude perlite were produced, sold or used by U. S. producers, and this figure increased to 325,0003 short tons by 1959. Such a rate of increase indicates the rapid and continuing growth of the perlite industry. GEOLOGY Perlite ore in its crude form has been found in seven of the mountainous western states, since un-devitrified siliceous volcanic rocks are limited to this section of the U. S. Commercially operated perlite deposits are normally of Eocene and Oli-gocene age.4 These deposits are often several hundred feet thick and may extend over hundreds of acres. In 1959, 13 companies in six states produced crude perlite, although the output in New Mexico comprised 79 pct of the total domestic crude output. Other states in order of their production were: Nevada, Arizona, California, Colorado, and Utah.5 Foreign deposits of perlite which are either producing or under exploration are Australia, Canada, Greece, Hungary,6 Iceland, Ireland, Japan, Mexico, New Zealand, and Sardinia. The ore may exhibit a variety of characteristics depending partially on its water content and eruption history and may range through many shades from black to white. While these characteristics may vary slightly among deposits, perlite ore from a particular source is normally quite uniform. Available chemical analyses of perlites from a large sampling of domestic deposits were recently assembled by the Technical Committee of Perlite Institute and are presented in Table I. While the ranges given do not apply to a particular perlite, they are an indication of the chemical analysis which may be expected from any presently commercially operated deposit. The specific gravity of the perlite ore ranges between 2.2 and 2.4, and its bulk density when crushed and sized is 75 to 90 Ib per cu ft. MINING AND MILLING Perlite ore is quarried from open pits by conventional power equipment, although blasting has been occasionally employed. The rock is then stock-piled until needed. While the milling of perlite may seem a simple process compared to that required for basic metals, or even other nonmetals, the need for accurate control of particle size becomes extremely important in further processing. The first step in this operation is the primary crusher, which is normally a jaw crusher. Following crushing, the material is dried, if necessary, in a rotary dryer and conveyed to a secondary grinder which may be a rod mill, hammer-mill, or cone crusher. However, the crushing characteristics of the perlite, caused by incipient cooling fractures, requires it be removed from the grinding operation once it is reduced to the required size so as to prevent overgrinding. Following the grinding operations, various size screens are used to separate the ore according to particle sizes required for particular uses. Most plants use two or more stages of crushing with perhaps four stages of screening.

Jan 1, 1961

By William C. Schulte, Gilbert E. Doan

An extensive program of investigation is being carried out at Lehigh University in the study of arcs and arc welds of high-purity iron1, sponsored by the Engineering Foundation. The part of that program reported in the present paper deals with welds made of high-purity iron in an argon atmosphere and for comparison with them welds made of the same iron in ordinary air. Welds of commercial steel also were made in argon and in air. The primary purpose of the study is to discover the basic physical constants of iron welds when not contaminated either by impurities in the iron or by the action of oxygen and nitrogen of the air during welding. Upon these constants can be founded such future studies as will determine what effects the various impurities and alloy elements present in steel have upon its welding characteristics, and what influence is exerted by the action of oxygen and nitrogen. The welding of steel involves such a multitude of variables, both of composition and of procedure, that development in the fabrication of this most important metal has necessarily been slow, wasteful, and in many instances discouraging. In the present investigation, the simplest possible condition has been selected; namely, iron practically free from contamination and a nonparticipating atmosphere, the inert gas argon. This simplification reduces the number of variables to a point where more rigid control of the system is possible. Although this study is significant for the contributions it makes to the science of steel fabrication, yet it is hoped that it will not be without value also in increasing knowledge of the. nature and behavior of iron and steel in general. From the standpoint of open-hearth practice, and to some extent from the standpoint of electric-furnace practice also, the conditions of melting and casting iron in this investigation are extraordinary. The casting temperature is high, the mean temperature of the metal probably reaching 2000' C. (3600' F.)? The rate of chilling of

Jan 1, 1936

By Allan B. Bowman

Several years ago a wealthy Chinese business friend of mine purchased an interest in a pro- posed oil well to be drilled a great distance from his home. A few months later it came in as a producer and proved to be a huge success and materially added to his resources. I asked him why a man of his wealth should be so lucky in a venture outside his sphere of knowledge when most people of modest means never seemed to get ahead. His answer was, "Fat Hoy takes a chance." Even though this was his answer, I knew from my association with him that there were other tempering considerations which Mr. Hoy applied before making up his mind to enter any transaction. First, he was a cautious individual. He was also a great believer in details and insisted on knowing everything possible about a situation, and finally, he was what we call a very solid individual with good basic instincts and judgment. This philosophy of Mr. Hoy may be applied to most any business but especially to those engaged in a search for natural resources such as mining where great risks are involved. This article concerns events in the history and growth of Banner Mining Co., with which I have been associated for 27 years in capacities from mine surveyor to vice president. Mr. Hoy's philosophy has played a significant role in the exploration projects of this company over the years, but what is more important, the officers, directors, and controlling interests in Banner have been aggressive in their search for ore reserves.

Jan 6, 1963

By R. I. Jaffee, J. G. Dunleavy, W. Hodge, H. R. Ogden

IN a search for an improved conductor for use in field wire for the L. S. Army Signal Corps, an alloy of copper and silver was developed from which it was possible to obtain 29 B & S ga. strands with tensile strengths in excess of 160,000 psi combined with an electrical conductivity of over 70 pct IACS. Such a favorable combination of strength and electrical conductivity has not been reported previously in the rather extensive literature covering this subject. The properties obtained from various binary alloys of copper and silver, together with the method of fabrication of these alloys which has been developed to obtain the properties desired in fine wire strands, are discussed in this paper. LITERATURE The effect on the electrical conductivity of copper of the various elements in solid solution is shown in Fig I, taken from published data by J. O. Linde and others.' It will be noted that silver in solid solution depresses the electrical conductivity to a lesser extent than any other element for which data are given, and is followed rather closely by cadmium, and then by chromium. Zinc, which lies between cadmium and chromium, has so high a solid solubility in copper that the data for zinc are scarcely comparable to the data for the other two in the range covered. Not many data are available on the strain hardening of copper-rich Cu-Ag alloys. Corson2 reports a 3 pct Ag alloy properly cold worked and annealed to have 100,000 psi tensile strength and 90 pct IACS conductivity. On straight cold working, Hessenbruch3 reports 101.000 psi for a 5 pct Ag, 0.3 pct Be alloy, and 129,000 psi for a 30 pct Ag, 0.5 pct Be alloy. Here it would he expected that much of the strain hardening came from the silver content of the alloys. The copper-rich side of the Cu-Ag diagram, according to Stockdale,4 is shown in the upper part of Fig 2. The electrical conductivities for copper-silver alloys annealed at 750 and 350°C, taken from the work of Johansson and Linde,5 are shown in the lower part of Fig 2. The sloping line corresponds to the conductivity of solid solutions of silver in copper, and the horizontal offshoots correspond to the conductivity of the two-phase alloys in equilibrium at the two temperatures shown. The electrical conductivities are very high, even for the 750°C anneal. The potentiality for age hardening from supersaturated alpha copper solutions appears to be excellent from the solubility line, but Smith and Lindlief6 have shown that the response to age hardening of solution-annealed alpha alloys is not good. They found that the tensile strength of a 5 pct Ag alloy aged at various temperatures was not as great as in the quenched condition, even though, anomalously, the hardness increased from RB68 to RB78 by annealing for 4 hr at 400°C after a 750°C quench. Weist7 also found that the alloys increased in hardness

Jan 1, 1948

By J. O. Brittain, E. P. Lautenschlager, F. Felberbauer

This investigation was undertaken to evaluate the effect of a dispersed phase in a iron upon the strain hardening and the stress dependency of dislocation velocity as inferred from the strain-rate sensitivitv. Experiments were made in a-iron specimens with controlled amounts of carbon and/or A12O3. They were tested at various temperatures between 195' and 373 'K under a variety of conditions oj-concentration, strain rate, and quench aging. The resulting yield strength, flow strength, and strain hardening increased with addition of Al2O3. The parameter m, measured from changes in strain rate, was xsed to describe the stress dependency of the dislocation velocity. m was found to increase with additions of A12O3, increasing carbon in solution, and with increasing temperature. When applied to a recent model for yielding based upon dislocation multiplication and velocity characteristics, the values of m alone did not successfully predict yielding for the materials of this investigalion, but had to be adjusted with a consideration of the number of unlocked dislocations nucleated heterogeneously at discontinuities or inclusions. The change of yield strength with Al2O3 Interpar-ticle spacing appeared to obey a theory of Orowan. EVER since the concept of dislocations has been introduced to explain plastic deformation in crystalline materials, the origin of dislocations and the source of the number of dislocations required to account for plastic deformation have been persistent questions. Ruling out the possibility of homogeneous nucleation,' Gilman2 drew attention to the various cases of heterogeneous nucleation as the source of dislocations, whereas Frank and Read3 introduced the Frank-Read source. However, Gil-man found that the Frank-Read sources did not play a dominant role in the deformation of LiF crystals, but that small precipitates are often, if not always, associated with the nucleation of dislocations. In LiF crystals, however, most of the dislocations arose through the multiplication of moving dislocations in a mechanism described by Koehler4 and Orowan,5 Thus, relatively few precipitates could account for a large number of dislocations. A similar observation of dislocation nucleation at inclusions of precipitates was made by Stein and LOW' on Si-Fe crystals. Their crystals contained

Jan 1, 1964

By M. C. Flemings, T. S. Piwonka

Pore formation is examined analytically in cellu-larly solidified single crystals, in cylindrical castings of pure metals and alloys, and in unidirectionally solidified castings. Effects are considered of fluid flow. dissolved gas, and surface tension. Experimental results show that flow through a partially solid "mushy" aluminum alloy obeys relations similar to those applicable for flow through other types of porous beds. Flow rate is proportional to the square of the fraction liquid (fL) for fL less than 0.3. Results indicate models chosen for mathematical description of pore formation in alloy solidification are valid. ONE of the solidification variables which is influential in determining mechanical properties of castings and of wrought material produced from cast ingots is porosity. This porosity may result from shrinkage, dissolved gases, or a combination of both, and may take the form of either macroscopic pores in localized areas of the casting or microporosity evenly distributed throughout large areas of the casting. In alloys which freeze over a range of temperatures some microporosity is generally found after solidification. There has been much discussion as to whether the micropores are caused primarily by shrinkage, by gas, or by a combination of both.'-3 There has, however, been little experimental or analytical work performed to delineate the relative contributions of shrinkage and gas in causing microporosity or to quantitatively describe the influence of processing variables on microporosity. Porosity other than microporosity (e.g., center line shrinkage) has also received only limited quantitative treatment.495 The aim of this work is to examine analytically the general problem of pore formation in solidification and to perform limited confirmatory experiments. Consideration is first given to shrinkage porosity in pure and nearly pure metals (shrinkage in cellular growth, centerline shrinkage in cylinders). Next, a discussion is given of formation of shrinkage-caused microporosity in unidirectional solidification and in "mushy" solidification. Finally, influences of dissolved gas and surface tension on microporosity are examined. Numerical results are given for aluminum and an aluminum alloy. Typical examples of microporosity are shown in Figs. 1 to 3, for 1) cellularly solidified aluminum, 2) sand-cast aluminum alloy, and 3) low alloy steel. SHRINKAGE POROSITY IN PURE AND NEARLY PURE METALS 1) Cellular Growth. In cellular freezing of an impure liquid, liquid grooves may exist over a considerable length of the growing crystal.6 The cross-sectional area of the grooves decreases with increasing distance from the cell tips; the root of the groove is blunt if the liquid at this point reaches eutectic composition. As a result of volume contraction during solidification, flow occurs down the groove, parallel to the growth direction; hence, there must be a pressure drop from the groove entrance to points within the groove. The geometry of the groove is simplified to that of a circular cylinder of radius r and length L, Fig. 4, L » r, and a simple and useful limiting case is obtained. This is that, in the circular cylinder freezing at constant velocity, the pressure at the root of the groove is lower than that pressure at radius r in grooves of other geometries where r decreases continuously to a lower limit at L. As discussed below, a pore resulting from a given pressure difference

Jan 1, 1967

By G. Rowan, M. W. Clegg

The basic equations for the flow of gases, compressible liquids and incompressible liquids are derived and the full implications of linearising then discussed. Approximate solutions of these equations are obtained by introducing the concept of a disturbed zone around the well, which expands outwards into the reservoir as fluid is produced. Many important and well-established results are deduced in terms of simple functions rather than the infinite series, or numerical solutions normally associated with these problems. The wide range of application of this approach to transient radial flow problems is illustrated with many examples including: gravity drainage of depletion-type reservoirs; multiple well systems; well interference. INTRODUCTION A large number of problems concerning the flow of fluids in oil reservoirs have been solved by both analytical and numerical methods but in almost all cases these solutions have some disadvantages — the analytical ones usually involve rather complex functions (infinite series or infinite integrals) which are difficult to handle, and the numerical ones tend to mask the physical principles underlying the problem. It would seem appropriate, therefore, to try to find approximate analytical solutions to these problems without introducing any further appreciable errors, so that the physical nature of the problem is retained and solutions of comparable accuracy are obtained. One class of problems will be considered in this paper, namely, transient radial flow problems, and it will be shown that approximate analytical solutions of the equations governing radial flow can be obtained, and that these solutions yield comparable results to those calculated numerically and those obtained from "exact" solutions. It will also be shown that the restrictions imposed upon the dependent variable (pressure) are just those which have to be assumed in deriving the usual diffusion-type equations. The method was originally suggested by Guseinov,1 who (a) postulated a disturbed zone in the reservoir, the radius of which increases with time, and (b) replaced the time derivatives in the basic differential equation by its mean value in the disturbed zone. In this paper it is proposed to review the basic theory leading to the equations governing the flow of homogeneous fluids in porous media and to consider the full implications of the approximation introduced in linearising them. The Guseinov-type approximation will then be applied to these equations and the solutions for the flow of compressible and incompressible fluids, and gases in bounded and infinite reservoirs obtained. As an example of the application of this type of approximation, solutions to such problems as production from stratified reservoirs, radial permeability discontinuities; multiple-well systems, and well interference will be given. These solutions agree with many other published results, and in some cases they may be extended to more complex problems without the computational difficulties experienced by other authors. THEORY In order to review the basic theory from a fairly general standpoint it is proposed to limit the idealising assumptions to the minimum necessary for analytical convenience. The assumptions to be made are the following: 1. That the flow is irrotational. 2. That the formation is of constant thickness. 3. Darcy's Law is valid. 4. The formation is saturated with a single homogeneous fluid.

By Francis C. Krauskopf, Carl E. Swartz

Metallurgists differ considerably in their opinions regarding the effect, if any, of small amounts of iron pyrites, or other iron compounds on zinc sulfide ores during the roasting operation. As a result, the literature on this subject expresses many conflicting ideas. The ore, previously crushed to pass through a 1-mm. screen, dries in the roasting kiln, losing water up to 200° to 300° C. At 150° C. iron pyrites begin to lose sulfur. As the temperature increases, while the ore is passing to the hotter part of the furnace, the sulfur burns to sulfur dioxide, leaving the metals as zinc oxide and ferric oxide. These two substances then interact to form zinc ferrite, a compound, yellow brown in color, having the general characteristics of a spinel. Like magnetite, another spinel, zinc ferrite is insoluble in alkalis and dilute acids. As a result, when leached with 10 per cent. sulfuric acid solution, zinc values tied up in this compound remain behind History In the electrolytic recovery of zinc from its ores, the roasted ores are usually leached with a 10 per cent. sulfuric acid solution. When the zinc ore contains iron pyrites as an impurity in an appreciable amount, the actual yield of metallic zinc is much lower than a theoretical calculation would indicate. Further, losses of zinc are, in a rough way, directly proportional to the amount of iron pyrites or other iron compounds present. When the iron is present in the ore in an isomorphous relation to the zinc, as in the case of a marmatite, a greater amount of zinc remains insoluble than when present as a true pyrite or marcasite. Work on the insoluble residues obtained from leaching of the calcines shows that the zinc lost is intimately tied up in this residue. Some investigators have suggested a definite compound, such as zinc ferrite; others merely a mixture of zinc and iron compounds. As early as 1851, Pelouze(')' prepared calcium ferrite by fusion of calcium oxide and ferric oxide. Ebelman, 2) about the same time, prepared

Jan 1, 1928

By William Kelly, F. H. Armstrong

The object of this paper is to describe the electric equipment at the iron-ore mines of Penn Iron Mining Co., Vulcan, Mich. and of Republic Iron Co., Republic, Mich.; to give the results of tests; and to discuss the methods in use from an operating as well as from an efficiency standpoint. Electricity was introduced at the Penn mines for pumping, hoisting, and compressing air in the spring of 1907, upon the completion of a hydro-electric plant built by that company on the Menominee river about 4 miles from the mines. This plant was described in a paper1 presented before the Lake Superior Mining Institute. A paper2 presented at a meeting of the same Institute describes some of the operating features, and the safety devices of the electric hoist at the Curry shaft were briefly described in the Proceedings of the First Co-operative Safety Congress held under the auspices of the Association of Iron and Steel Electrical Engineers at Milwaukee, Wis., Sept. 30 to Oct. 5, 1912. Generating PoweR Plants After the success of electrical operation was assured, a second set of water wheels and generator was installed at the falls, for which provision had been made in the original design and in the construction of the foundations, and later three additional wires were added to the main transmission line, doubling its capacity and reducing the line loss. The general conditions of this installation are particularly favorable for hydro-electric operation. In the neighborhood of three-fourths of the power used is for mine pumping, which in the main is regular and continuous. For air compressing, power is used for about 18 hr. a day for five days, and 9 hr. for one day in the week, though occasionally when shaft sinking is going on a very small amount of compressed air may be

Jan 1, 1915

By Hugh O?Neill

IN PREVIOUS papers,1 the author has reported the results of experiments on the straining in tension of a single crystal test piece, about 0.6 in. long, of vacuum-melted electrolytic iron containing 1.8 per cent. of silicon. The crystal was originally in the "as cast" condition, and was stressed slowly along a tetragonal axis so that slipping along conjugate gliding planes finally transformed the original cylindrical portion into a pair of fracture wedges. One of these fracture wedges was sectioned along the stress axis in a plane at right angles to the edge of the wedge. A metallographic study of this plane of -section led to the conclusion that slip had taken place in the (111) direction along (112) planes making a V shape with the stress axis. The present paper describes the results of scratch-hardness tests conducted on the same section, in order to determine the distribution of strain hardness therein, followed by annealing, and considers the resulting variations in hardness. These observations supplement those made by Krivobok2 on similar material reduced 25 per cent. by hammering (i. e., by impact) in the cold. In order to investigate ageing effects, two small crystals of the same alloy were also tested.

Jan 1, 1928

By E. S. Rowland, Clair Upthegrove

The widespread interest in the alloys of beryllium with copper is due principally to the fact that certain compositions show very favorable precipitation-hardening characteristics and are, in fact, the stronges nonferrous alloys known at the present time. Investigations have been conducted by Masing and Dahl and others on the physical characteristics of ternary beryllium alloys, in an attempt to produce precipitation hardening effects with a smaller amount of beryllium than that required in the binary copper-beryllium alloys (2.0 to 2.5 per cent Be). The results of these investigations show that ternary alloys of beryllium with Cu-Sn, Cu-A1 and Cu-Zn, among others, exhibit promising improrcmc~nts in physical properties after precipitation-hardening treatment and, while the increases in properties obtained are not as high as those reahzed from the binary copper-beryllium alloys, excellent properties arc obtaincd with beryllium contents averagirlg about one-half the amount reqnired in the binary alloys. This paper presents the results of an investigation of the equilibriun relations of certain alloys containing copper, tin and beryllium. The alpha-phase boundary of the ternary system is given for alloys containing from 0 to 1 per cent beryllium. The equilibrium conditions beyond the alpha-phase boundary are presented for alloys containing up to 32 per cent tin and 1 per cent beryllium. The data were collected by means of quenching experiments, microscopic examination and thermal analysis The results of some powder-method X-ray determiniations on the alloys, conducted by Mr. William Mikulas and Prof. Lars Thomassen at the University of Michigan, are used as evidence in this paper. The con

Jan 1, 1935

By R. S. Craig, W. E. Wallace, G. S. Kamath

The destruction of long-range order in Mg-Cd, has previously been thought to occur as a second order process. In the present work a variety of X-ray diffraction techniques are employed to show that in this case and in Mg-Cd alloys containing frorn 20 to 33 1/3 at. pct Mg the process more nearly resembles an ordinary first order phase transformation. It is found that the ordered alloy, which occurs as a single phase at lgw temperatures, transforms with increasing temperature into a Cd-enriched disordered (P) phase and an Mg-enriched ordered (a) phase. The interval over which these two phases coexist under apparently equilibrium conditiovs extends from 25" to 87°C content. At 33 1/3 at. pct Mg the two-phase region has disappeared. Measurement of the long range order parameter, s, for the ordered phase in MgCd, (from superlattice line intensities) shows that it disorders only very slightly before it is transformed into the p form. Kinetic experiments reveal that when the a phase is formed frorn the p phase by suitably quenching so as to suppress phase segregation, the transformation is essentially complete and the a phase has acquired its equilibrium value of S in less than 1 min. In an earlier investigation carried out in this Laboratory1 the rate of disordering of the MgCd3 superlattice was determined over an extensive range of temperature. The process was found to be first order and the rate constant, k, was established. At the lowest temperatures studied k was found to increase exponentially with temperature. At higher temperatures, however, it passed through a maximum and for the 100 deg interval below the point at which the superlattice was destroyed k was observed to decrease with increasing temperature. The various theoretical treatments1-3 of order-disorder phenomena lead to a negative temperature coefficient for k near the superlattice critical temperature but this region for MgCdB seemed unusually wide. Detailed analysis of the point indicated' that either the long-range order parameter, S, for MgCda varied with temperature in an anomalous way or the disordering in this instance is more complex than in the cases which have been treated theoretically. The original objective in the present work was simply to determine S vs temperature for MgCda to ascertain whether the disordering was in conformity with theoretical expectations.2° In an early stage of the work it was noted, however, that under equilibrium conditions ordered (a) and disordered (0) phases coexist in MgCd, over a considerable range of temperature. Since on thermo- dynamic grounds the coexisting phases must differ in composition, the investigation was enlarged to permit the compositions of the two phases in MgCd3 to be determined and to establish the extent of the two phase regions for alloys containing from 20 to 33 1/3 at. pct Cd.

Jan 1, 1963

By P. W. Bakarian, C. H. Mathewson

THE greater part of the literature on the plastic behavior of magnesium dates back to that active period of research in crystal mechanics immediately following the widespread preparation of isolated metallic crystals large enough for the application of conventional methods of mechanical testing. These investigations, performed on single crystals, revealed an analogy between zinc and magnesium with respect to their fundamental mode of deformation, in the operation of glide and twinning, respectively, on crystallographically similar planes. Mathewson and Phillips (1928)1 by geometrical analysis identified the {102} ? plane in magnesium as the twinning plane, Schiebold and Siebel (1931)2 confirmed this twinning plane, established the basal plane as the plane of slip, and a digonal axis I as the slip direction. They also reported twin formation in a secondary role on the {101} plane. Schmid (1931)3 summarized and discussed the earlier evidence and presented the results of his own experiments on the effect of temperature and small amounts of soluble elements. From X-ray studies on extended wire single crystals, he concluded that slip along the basal plane in the direction of the digonal axis I closest to the stress direction was the sole slip system operating at atmospheric temperature. This conclusion was based on experiments with crystals of many different orientations relative to the stress axis. Special attention was directed to the basal plane and the digonal axis I, as the plane and direction of greatest atomic density. Determinations of resolved shear stress at the onset of plastic yielding-i.e., the critical resolved shear stress-were also made; the average of these calculations showing 82.9 grams per sq. mm. This value varied only slightly up to 300°C., at which temperature it was found to decrease to 70.5 grams per sq. mm. The extension of his crystals at temperatures above 225°C. further disclosed the presence of new slip systems. After the original specimens of circular section had been

Jan 1, 1943

By A. F. Taggart, A. M. Gaudin

Flotation of ores is a practical utilization of the energy that resides in the surfaces of solids and liquids. The best known manifestation of this energy is called surface tension; an equally important, though less apparent, phenomenon is adsorption. This paper reviews some of the recent investigations of these phenomena, and gives the results of certain experiments performed by the authors. Surface tension is a manifestation of energy having its seat at the bounding surface between the adjacent phases of a multiphase system. Thus, at the interface between a liquid and a gas, or between two immiscible liquids, or between a solid and a gas or a liquid, there are forces capable of doing work, their magnitude depending on the nature of the adjacent phases and the extent of the bounding area. These surface forces are inappreciable when the ratio of surface to volume of the adjacent phases is small, but they become powerful when this ratio becomes large, as it does when one of the phases is highly dispersed. Froth flotation, which consists in buoying solids heavier than water to the surface of water by means of gas bubbles, utilizes the force of surface tension to attach the solid particles to the gas bubbles and again to maintain the floating mass of bubbles as a more or less persistent froth at the surface of a pulp for a sufficiently long time to allow its removal. It follows from the second law of thermodynamics that the potential energy of a system in equilibrium is a minimum. Therefore a multiphase system, tending toward equilibrium, will arrange itself in such a way that the total energy of the interfaces will be the least possible. This end can be accomplished in two ways: by a change in shape that will reduce the interfacial area; by a change in the nature of the surface layer in

Jan 1, 1923

By G. Bhat, J. F. Libsch

lsoembrittlement curves depicting the influence of time and temperature in the range 800' to 1260°F (425' to 680°C) on the development of embrittlement in a commercial chromium alloy steel and a commercial molybdenum alloy steel are presented. Two distinct regions of embrittlement occur in the chromium alloy steel: I—at 800' to 1000°F (425' to 540°C) and 2—in the region just below the lower critical temperature. Embrittlement is most pronounced at 800' to 1000°F, decreasing very rapidly with increasing temperature above this region, only to increase again as the lower critical temperature is approached. The data suggest two distinct modes of embrittlement with possible superposition of the two modes at extended embrittling times in the temperature range 1100° to 1150°F (590' to 620°C). While the molybdenum alloy steel shows little susceptibility to embrittlement at 800' to 1000°F (425' to 540°C), considerable embrittlement may occur just below the lower critical temperature. THE subject of temper embrittlement in alloy steels has received considerable attention in the last few years. Points of view on the mechanism of embrittlement differ, however, resulting in part from the incompleteness of the data developed and in part from the speculation regarding the susceptibility of plain carbon steel to temper embrittlement. Libsch, Powers, and Bhat1 carried out short-time embrittling treatments on an AISI 1050 steel and demonstrated that hardened plain carbon steels are quite susceptible to embrittlement when tempered in the range from 850°F (455°C) to the lower critical temperature. The isoembrittlement diagram,' representing the embrittling characteristics of this steel, is reproduced in Fig. 1. It is evident from the shape of the curves shown that embrittlement in plain carbon steel increases progressively with both temperature and time in the embrittling range. A comparison of the isoembrittlement diagram for AISI 1050 steel with that presented by Jaffe and Buffum' for an SAE 3140 steel shows that up to 930°F (500°C) the isoembrittlement characteristics of the plain carbon steel are similar to those of SAE 3140 steel, although the embrittlement is much more severe in the latter steel. Above 930°F (500°C), the rate of embrittlement in the plain carbon steel increases continuously with increasing temperature; whereas, in the SAE 3140 steel, the embrittlement rapidly decreases. The influence of alloying elements upon embrittlement during tempering thus appears to cause a decrease in embrittlement above the region of maximum embrittlement, i.e., 850" to 1000°F. The question naturally arises as to what effect individual alloying elements have upon the embrittling characteristics of the plain carbon steel. Current knowledge on the influence of alloying elements on temper brittleness may be found in the review papers of Hollomon" and Woodfine. Hollo-mon," from the results of other investigators, has shown that, in general, the amount of embrittlement increases with increasing alloy content (except for molybdenum and possibly tungsten and columbium). Jaffe and Buffum," by a comparison of the embrittlement in a plain carbon steel with that of a SAE 3140 steel postulated that the presence of alloying elements in moderate amounts tends to retard the development of temper brittleness. It is difficult to determine what effect chromium has upon temper brittleness, since most of the information available has been based on the combined effect of other elements with chromium, particularly nickel and manganese. However, Wilten, and recently Jolivet and Vidal,' Vida1, and Woodfine have reported that chromium steels are temper brittle, that the embrittlement is reversible with a maximum rate of embrittlement at approximately 975°F (525"C)," and that the susceptibility increases with increasing amounts of chromium. Taber, Thorlin, and Wallacel" have found a large embrittling effect with increasing chromium content in a medium C-Mn-Ni steel. But Hultgren and Chang," from their experiments conducted on synthetically prepared ternary Fe-C-Cr alloys, could not conclude that these alloys are susceptible to temper embrittlement. However, on addition of manganese or phosphorus, these Fe-C-Cr alloys became susceptible, from which fact they concluded that the embrittlement developed in chromium-bearing Fe-C alloys is due chiefly to the presence of these elements. Considerable data are available to show that molybdenum decreases the susceptibility of steel to temper embrittlement. However, its effectiveness in preventing or decreasing embrittlement appears limited to its presence in small amounts. Vidal" has shown that a plain 2 pct Mo steel was susceptible. Hultgren and Chang" also have shown that molybdenum additions in excess of 2 pct to synthetically prepared Ni-Cr steels did not prevent embrittlement. Jolivet and Vidal' and Lea and Arnold found that molybdenum reduced temper brittleness. Lea and Arnold further stated that molybdenum decreased the rate of embrittlement rather than the total amount of embrittlement, whereas Preece and Carter" have shown that the presence of molybdenum greatly reduces the equilibrium extent of the change at a given temperature but does not appear to influence the rate of embrittlement. There appears to be very little information as to how molybdenum by itself affects the temper brittleness susceptibility of a plain carbon steel.

Jan 1, 1956

By R. C. Craze

This paper discusses the characteristics of the velocity logs now available to the petroleum industry, and some of their advantages and limitations. The velocity log was designed as an aid to the geophysicist to determine velocity layering in the earth and to provide fast, accurate and economical vertical travel time data. After a number of logs had been made, studies were carried out on their use ia correlating strata in adjacent wells. It was found that adjacent strata usually show sufficient velocity contrast to make it possible to correlate these from well to well, even in areas where electric or radioactive logs fail.' In addition, velocity logs have been useful in the determination of porosity and thickness of reservoir rock.' These uses for velocity logs require an understanding of the characteristics of the log in response to the changes in velocity and in borehole conditions encountered normally in logging. GENERAL DISCUSSION OF INSTRUMENTATION The measurement made in velocity logging is more accurately described as a measurement of time rather than velocity. Ideally the log is obtained by measuring the length of time required for compressional sound waves to travel through a fixed distance in the formation. In practice, the time measurement may be made accurately but the distance through which the waves have traveled may vary slightly. Changes in borehole diameter are responsible largely for the difficulty in maintaining a fixed distance, especially if the diameter variations are so abrupt and frequent that the borehole instrument cannot follow contours of the hole. Several service companies have velocity logging equipment available or under development which have different transmitters, receivers, and measuring systems. While these differences are important, there are actually only two systems in use at the present time (Fig. I)."' The first system initiates a pulse at a trans-mitter and detects it at a single receiver. The transmitter and receiver are separated by a fixed distance, called the spacing. The time measured is that between the initiation of the pulse and the first arrival of acoustical energy at the receiver. The second system uses two receivers and a transmitter. The receivers are separated by a fixed distance and the time between arrivals of energy at the two receivers is measured. Here, the spacing is the distance between receivers. The two systems have much in common for it is possible to record both logs simultaneously. Usually the transmitter is an electro-mechanical transducer which produces discrete