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By N. A. D. Parlee

THE gas-liquid metal diffusion cell technique1-3 has been used to study the diffusion of nitrogen in Fe-C alloys. The actual apparatus and technique were the same as employed by the authors to study the diffusion of hydrogen in liquid iron.' The diffusion cell' was formed by immersing an alumina tube in a stagnant melt contained in an alumina crucible. The tube (hereafter called absorption tube) contained nitrogen gas at 1 atm and was connected to a sensitive gas-measuring system. The change in the average concentration of nitrogen in the melt in the absorption tube was determined by measuring the rate of absorption of nitrogen in the diffusion cell. Eq. [I], 1-3 derived from the appropriate solution of Fick's second law, was used to examine the data and to calculate chemical diffusion coefficients (D) in situations where the absorption appeared to be controlled by diffusion in the liquid: where V is the stp volume in cu cm, d is the diffusion cell diameter in cm, p, is the density of the melt in g per cu cm, pg is the stp density of nitrogen in g per cu cm, C, is expressed in wt pct, D is in sq cm per sec, and t is in min. According to Eq. [I], a plot of v vs vt should yield a straight line passing through the origin if absorption is controlled by diffusion in the liquid. The slope of this line could be used to determine the value of D under appropriate conditions. As discussed in earlier reports,1,2 the initial thermal expansion of the gas upon immersing the absorption tube distorts the line in the initial stages of a diffusion experiment. However, this is not a serious problem since the slope of V vs 6 plots can be determined from the data points obtained after the initial expansion ceases. The volumes reported on the data plot presented here represent absorption after this thermal expansion ceased. Several preliminary diffusion experiments were attempted with melts of pure iron and with Fe-C alloys containing up to 0.6 pct C. In these cases, no or very little absorption was observed. The only data obtained were for an Fe-C melt which was in addition thoroughly deoxidized by successive hydrogen and vacuum-degassing treatments. These treatments introduced an appreciable amount of aluminum into the melt and reduced its omgen content. The original charge material for this melt contained 0.23 pct s and approximately 0.001 pct &. After repeated hydrogen and vacuum-degassing treatments two diffusion experiments were performed. The analysis of the melt

Jan 1, 1968

By Robert J. De Angelis, James H. Barker

An improved method for solving dynawzical dislocation problems using a digital computer is described in this paper. Interactions between two distinct types of dislocations were studied: attractive screw dislocations; and Lomer lock forming dislocations. One dislocation is positioned in the lattice and is initially at rest, while the other dislocation is moved through the lattice on an intersecting slip plane at a constant velocity in the range 0.5 to 0.999C. (C is the transverse velocity of sound.) The results obtained from these computations indicate that screw dislocations account for a small fraction of the total strain over a wide portion of the range of velocities studied. They further indicate that mixed dislocations mainly repel other dislocations in the neighborhood of the active glide plane. From this a possible explanation for cell formation is put forth. The density of Lomer locks expected to exist after a strain of 0.2 was found to be 1.4 x 106 cm-2 which is in good agreement with indirect experimental estimates. IN the past, predictions of favorable or nonfavorable dislocation reactions were based on the associated changes in elastic strain energy. Such considerations take no account of the probability of the two dislocations coming into contact to react. Venables1 was the first to approach these probabilities by considering the interactions between two moving screw dislocations on perpendicular glide planes. Because of the restrictive types of dislocations and glide plane geometry employed, his results have limited application to metallic crystals. The work to be presented here develops a general approach to solving dynamical dislocation problems; either dislocation-dislocation interactions, presented here in detail, or dislocation interactions with any other suitably defined stress field. Two types of dislocation-dislocation interactions common to face centered cubic (fee) materials are considered: those between pure screw dislocations of opposite sign on intersecting slip planes and those between mixed dislocations on intersecting slip planes, that can react to form a perfect dislocation. This latter reaction, referred to as the Lomer reaction, produces a locked product dislocation that finds it energitical favorable to disassociate into two Shockley partials and a stair-rod dislocation. This partial configuration known as a Lomer-Cottrell (L-C) lock plays a major role in work hardening of fee crystals. seeger2 names the L-C lock as the prime contributor to Stage II hardening while Kuhlmann-wilsdorf3 and Meakin and Wils- dorf4 also state that it is a significant contributor to work hardening. However, with a few notable exceptions,5-7 direct observations of the Lomer lock and the L-C lock by electron transmission microscopy are scanty, and even these are subject to other interpretations.5,6 In a study of partial dislocations present in austenitic stainless steel, whelan8 did not observe any L-C locks at the head of pile-up groups. This result contradicted existing work hardening theories and led him to postulate an alternate theory based on the stress required to break away dislocations intersecting a pile-up group, from their stacking fault nodes. Due to the importance of the Lomer reaction in producing L-C locks which are an essential feature in current work hardening theories and because there exist no data giving direct quantitative values for the density of locks, and because there has even been some doubt expressed as to whether this important reaction occurs at all, a study of the dynamic behavior of the mixed dislocations which form the Lomer lock was undertaken. Due to their ability to cross-slip with relative ease, screw dislocations play an important role in the deformation of fee crystals. For this reason, the second type of reaction considered here is between screw dislocations of opposite sign. In addition, computations in volving screw dislocation interactions are relatively simple, thus providing a convenient check on the cornputational scheme employed. DEFINITION OF PROBLEM The force exerted on a dislocation due to a generalized stress field is given by the Peach and Koehler9 equation: Here t2 and b2 are respectively the tangent and Burgers vectors of the dislocation, and T1 is the stress dyadic defining the local stress field. The stress field may be externally applied or generated internally by the presence of a lattice defect, such as a second dislocation, as is the case in this work. Frank10 has shown that an equivalent momentum, P, of a screw dislocation can be defined by: Here, EST is the total energy of a screw dislocation and ESo is its rest energy. The left side of Eq. [2] is the time derivative of momentum and the right side is the position derivative of the energy due to the dynamical nature of the dislocation. The total energy of a dislocation is the sum of the potential and kinetic energies. Weertman11 has developed the expressions which were used here; these give the potential and kinetic energies of uniformly moving edge and screw dislocations in an isotropic medium.

Jan 1, 1969

By W. W. Wirth

RESEARCH looking toward the reduction of the cost of roof support by substitution of longer-life materials for wooden timber is fully justified by the fact that roof support is an important element of all production costs. Permanent or semipermanent roof support will reduce the expense of timber-maintenance crews during steady operations, but even more markedly during idle periods. The management, therefore, is faced with the important problem of timber renewals, which in times of regular operation are frequently obscured by more urgent problems of production. Increased use of timber in the Anthracite Region of Pennsylvania is caused mainly by increased percentage of coal obtained from robbing areas, which requires more timber for safety than develop-ment work, and maintenance of long haulageways through crushed ground despite the fact that less coal is transported over them. The timber reserve in the immediate vicinity of the mines has been depleted to such an extent that it is necessary to secure 70 per cent of the timber requirements from distant sources. Originally, mine timbering in this region was done by largely utilizing round props or legs with round collars. The whole cross section of the tree from which timber was cut was utilized by forming the joints between the legs and the collars with saw and adze, using plank or round saplings for lagging behind the legs and over the collars to prevent material falling between them. The Mine Inspectors' report of 1898 records an important digression from the use of round timber, when two tunnels at the Babylon colliery, near Pittston, Pa., were timbered with 12 by 12-in. square timber sets with mud sills, through quicksand for distances of 425 and 160 ft., respectively. The timbers were lagged with 3-in. plank to control sand.

Jan 1, 1940

By G. G. Reed

G.G. Reed, Jr. The authors are to be commended for finding a material for pellets binding that we were unable to uncover during the investigations that led to US Patent No. 3,748,116, "Method for producing metallic iron powder from iron ore concentrate," July 24, 1973, by G.G. Reed, Jr., J.M. Karpinski, and S.V. Fox. This patent concerns a method of processing "super"-concentrates prepared from magnetite or "blue dust" into molding-grade metallic iron powder for use as a bulk commodity, in contrast to current methods which produce small batches that are custom-blended with additives and/or alloys to customer specifications. The one thing we had not found at that time was an organic binder (mineral-matter-free) that would allow induration to produce hardened pellets that would survive SL/RN Direct Reduction. Peridur appears to provide this missing link needed for large scale (200 t/a, or 220,460 stpy) single line plant capacity consistent with a low market price to ensure greatly broadened use of metallic iron powder. I hope that industry will adopt this combination so that metallic iron powder usage can fulfill its potential. ?

Jan 1, 1986

By D. F. Stein

In spite of the apparent usefulness of autoradiography in demonstrating segregation, it has had very limited success in demonstrating grain boundary segregation. Because of this limited success, a model system amenable to mathematical analysis was devised to determine which variables in the experiment are most important. As a result of these calculations, it was concluded that autoradiograPhy is a rather insensitive technique to measure grain boundary segregation. The range (energies) of the emitted particles (ß and a) must be low, and the concentration of the radioactive speczes at the grain boundary must be (in general) two or three orders of magnitude greater than the concentration within the grain. Because of these very restricted conditions , the limited success of the technzque is not surprising. In spite of the apparent usefulness of autoradiography in demonstrating segregation, it has had very limited success in demonstrating grain boundary segregation. Sulfur segregation in iron1 and possibly polonium segregation in Pb-5 pct B1 2 alloys are the only autoradi-ography experiments that have demonstrated segregation to grain boundaries in metals without the formation of a second phase. Segregation to a boundary without the formation of a second phase is often called Gibbs' absorption and is discussed by McLean in Chapter 5 of Ref. 10. There are several394 experiments showing grain boundary diffusion of a radioisotope, but this type experiment is not representative of equilibrium between the concentration of an element at a grain boundary and that in bulk, so it will not be discussed in this paper. In an attempt to determine if temper embrittle ment of low-alloy steels was associated with segregation of antimony to grain boundaries, a program to use auto-radiography (using Sb-125) was initiated. Even though other measurements strongly suggest that segregation is occurring during embrittlement, no evidence of grain boundary segregation was observed in the auto-radiography experiments. An attempt was also made to detect segregation of carbon (using C-14) to grain boundaries in iron during slow cooling. There is again strong indirect evidence7 that segregation occurs during such a treatment, but the autoradiography experiment gave no evidence of such segregation. Because of the failure of these experiments and the general lack of success by our metallographic unit in measuring grain boundary segregation using autoradi-ography, a model system amenable to mathematical analysis was devised to determine which variables in the experiment are most important. MODEL SYSTEM The model system is illustrated in Figs. 1 and 2. It is a semi-infinite bicrystal with a single grain boundary perpendicular to the top face. The width of the grain boundary, W, is defined as the region to which segregation has occurred and it is assumed that this region is of constant composition. The assumption of an infinite dimension is for mathematical reasons but the results of such an analysis (as will be demonstrated later) are valid for even very small specimens. It also is assumed that the measurement is not limited by means of detecting the radiation (photographic emulsions, counters, and so forth) but that the means of detecting radiation is linearly sensitive to the radiation and has infinite resolving power. The distance y is the perpendicular distance from the center of the grain boundary to the point at which the background radiation is measured and x is the integration variable. CALCULATION FOR BETA PARTICLES Two values of the intensity of radiation will be calculated, the intensity at the center of the grain boundary and the intensity far from the grain boundary. The radiation at the center of the grain boundary can be calculated in the following way. Assume a grain boundary of width W having a uniform concentration equal to Cgb + Cb where CGb is the excess concentration of the element under consideration at the grain boundary and Cb is the bulk concentration. The intensity of radiation, IgB, at the center of the grain boundary, is a consequence of the amount of radioactive material, decay rate, absorption, and geometrical factors which can be represented mathematically by the following expression:

Jan 1, 1968

By James W. Neill

The occurrence of minerals of nickel and cobalt at Mine La Motte is probably known to every mineralogist. I will not attempt to describe these minerals, but, before entering on my subject, will briefly mention the ores, etc., which call for metallurgical treatment and enter into the composition of our mattes. Our staple lead-ore, the dressed galena, is the chief source of nickel and cobalt. It carries but a small percentage of these metals, viz.: 0.2 to 0.3 percent. usually, though when much copper pyrites is contained in the gangue, the amount of nickel and cobalt may be as great as 1.0 to 1.5 per cent. Next in importance is the ((middle product" of the dressingworks, consisting of the sulphides of iron (and copper) with gangue and galena. This usually carries 20 to 23 per cent. of lead, 0.5 to 1.0 per cent. of copper and 2.5 to 3.5 per cent. of nickel and cobalt. A larger percentage of copper always carries with it an increase of nickel and cobalt. In some few cases 12 to 15 per cent. of copper gives 6.5 to 8.0 per cent of these metals. Resides these products of the dressing-works, there is a small quantity of true nickel-cobalt-ore

Jan 1, 1885

By David K. Mitchell

The mineral pyrite (or marcasite) occurs in coal beds as balls, lenses, veinlets and bands. Several million tons are w-asted annually on the refuse dumps from coal mining and coal-preparation activities. Sporadic attempts have been made in the United States to recover this pyrite for manufacture of sulphuric acid but only a few plants have succeeded in recovering it on a commercial scale. Shipments of pyrite from coal mines during 1941 were reported as follows: Illinois -The Midland Electric Coal Corp., Henry County, shipped 12,026 long tons containing 46 pct sulphur, at its Atkinson preparation plant. Indiana—The Snow Hill Coal Corp. produced pyrite from its Talleydalc preparation plant in Vigo County. Kansas—The Mineral Products Co. produced 3902 long tons of pyrite containing 44 pct of sulphur from picking table and washery refuse. Specifications for coal pyrite for acid manufacture rangc from 5 to 8 pct maximum carhon limit, and 42 to 45 pct minimum sulphur limit. Where flash roasting is practiced, the pyrite must be minus 100-mesh. Most companies give no size specifications. One company specifies 20- mesh or finer. Impurities in pyrite other than carbon may limit its use—for instance, arsenic, probably as arseno pyrite-—even though a concentrate can be made complying with specifications otherwise. Pyrite-recovery Plants Bradford breakers and picking tables may be used to make a marketable product where the pyrite occurs largely in sizes coarser than about I in. To make a grade of concentrate acceptable to sulphuric-acid plants the pyrite must break freely from the accompanying coal and slate, which is a rare condition to find. Most pyrite occurring in coal beds requires crushing and an abrasive type of grinding to free it of entwined coal and slate, followed by mechanical concentration by jigs, tables or other concentrating devices suitable for heavy ores, to make a satisfactory concentrate. At the Snow Hill Coal Corporation's plant in Indiana and at the Midland Electric Corporation's plant at Xtkinson, Ill., the final concentrate is made by a mechanical jig. The most recent and complete mill for concentrating pyritc from coal-mine refuse is that of the Mineral Products Co. at West Mineral, Kans., in which jigs and tables are used. Many regrinds and recirculations of products are necessary to get a concentrate of uniform grade. Trends On the whole, the economics of recovering pyritc from coal is not favorable. Cer-

Jan 1, 1948

By David K. Mitchell

The mineral pyrite (or marcasite) occurs in coal beds as balls, lenses, veinlets and bands. Several million tons are w-asted annually on the refuse dumps from coal mining and coal-preparation activities. Sporadic attempts have been made in the United States to recover this pyrite for manufacture of sulphuric acid but only a few plants have succeeded in recovering it on a commercial scale. Shipments of pyrite from coal mines during 1941 were reported as follows: Illinois -The Midland Electric Coal Corp., Henry County, shipped 12,026 long tons containing 46 pct sulphur, at its Atkinson preparation plant. Indiana—The Snow Hill Coal Corp. produced pyrite from its Talleydalc preparation plant in Vigo County. Kansas—The Mineral Products Co. produced 3902 long tons of pyrite containing 44 pct of sulphur from picking table and washery refuse. Specifications for coal pyrite for acid manufacture rangc from 5 to 8 pct maximum carhon limit, and 42 to 45 pct minimum sulphur limit. Where flash roasting is practiced, the pyrite must be minus 100-mesh. Most companies give no size specifications. One company specifies 20- mesh or finer. Impurities in pyrite other than carbon may limit its use—for instance, arsenic, probably as arseno pyrite-—even though a concentrate can be made complying with specifications otherwise. Pyrite-recovery Plants Bradford breakers and picking tables may be used to make a marketable product where the pyrite occurs largely in sizes coarser than about I in. To make a grade of concentrate acceptable to sulphuric-acid plants the pyrite must break freely from the accompanying coal and slate, which is a rare condition to find. Most pyrite occurring in coal beds requires crushing and an abrasive type of grinding to free it of entwined coal and slate, followed by mechanical concentration by jigs, tables or other concentrating devices suitable for heavy ores, to make a satisfactory concentrate. At the Snow Hill Coal Corporation's plant in Indiana and at the Midland Electric Corporation's plant at Xtkinson, Ill., the final concentrate is made by a mechanical jig. The most recent and complete mill for concentrating pyritc from coal-mine refuse is that of the Mineral Products Co. at West Mineral, Kans., in which jigs and tables are used. Many regrinds and recirculations of products are necessary to get a concentrate of uniform grade. Trends On the whole, the economics of recovering pyritc from coal is not favorable. Cer-

Jan 1, 1948

By F. M. Lewis, J. F. Myers

The crushing of ore, as defined by Taggart, is "usually a stage process, utilizing . . . machines especially suitable for the reduction of particular sizes. . . . down to a final stage, employed for the reduction of the finest sizes. ... In contradistinction, comminution to 20-mesh or finer is called grinding. There is a twilight zone in which the product is 6, 10, or 14-mesh limiting size which is either crushing or grinding. ..." Since the data in this paper pertain to a rod-mill operation, comminuting a particular ore size of ¾ in. to a final stage, coarser than 20-mesh, the rod mill is designated as a "fine crusher machine" in this paper. The published literature discloses a wealth of data regarding a rod mill as a fine-grinding machine but relatively little as a fine-crushing operation. Typical of the latter operation is: (I) a description by F. J. Tuck2 in which a fine-crushing rod mill replaced crushing rolls and (2) a description by the present authors3 in which a fine-crushing rod mill was installed instead of a collventional fine-crushing machine. The experience of the authors is that a definite distinction must he made between the rod mill functioning as a fine crusher and as a fine-grinding machine. As a fine crushing machine it prepares relatively large amounts of ore for a subsequent fine grinding operation; as a grinding machine, it grinds relatively small amounts of ore to some predetermined finished product. Pulp Movement and Action in Mill In considering the work performed by a fine-crushing rod mill, it seems important to understand just what takes place within the mill. We were inspired to study this matter by a paper by E. W. Davis,4 which indicated that definite water classification of ore particles took place in a ball mill. However, in thinking of the rod-mill action from this point of view, we were confronted with the fact that our rod-mill discharge product showed no evidence of action by water classification. The Tennessee Copper Co. ore is relatively high in sulphides, and the gangue rock and the sulphides are of about the same hardness. In the presence of any action by classification, the coarser sizes are definitely very lean in sulphide minerals.

Jan 1, 1947

By J. F. Myers, F. M. Lewis

The crushing of ore, as defined by Taggart, is "usually a stage process, utilizing . . . machines especially suitable for the reduction of particular sizes. . . . down to a final stage, employed for the reduction of the finest sizes. ... In contradistinction, comminution to 20-mesh or finer is called grinding. There is a twilight zone in which the product is 6, 10, or 14-mesh limiting size which is either crushing or grinding. ..." Since the data in this paper pertain to a rod-mill operation, comminuting a particular ore size of ¾ in. to a final stage, coarser than 20-mesh, the rod mill is designated as a "fine crusher machine" in this paper. The published literature discloses a wealth of data regarding a rod mill as a fine-grinding machine but relatively little as a fine-crushing operation. Typical of the latter operation is: (I) a description by F. J. Tuck2 in which a fine-crushing rod mill replaced crushing rolls and (2) a description by the present authors3 in which a fine-crushing rod mill was installed instead of a collventional fine-crushing machine. The experience of the authors is that a definite distinction must he made between the rod mill functioning as a fine crusher and as a fine-grinding machine. As a fine crushing machine it prepares relatively large amounts of ore for a subsequent fine grinding operation; as a grinding machine, it grinds relatively small amounts of ore to some predetermined finished product. Pulp Movement and Action in Mill In considering the work performed by a fine-crushing rod mill, it seems important to understand just what takes place within the mill. We were inspired to study this matter by a paper by E. W. Davis,4 which indicated that definite water classification of ore particles took place in a ball mill. However, in thinking of the rod-mill action from this point of view, we were confronted with the fact that our rod-mill discharge product showed no evidence of action by water classification. The Tennessee Copper Co. ore is relatively high in sulphides, and the gangue rock and the sulphides are of about the same hardness. In the presence of any action by classification, the coarser sizes are definitely very lean in sulphide minerals.

Jan 1, 1947

By J. A. Scott, F. R. Hensel

The paper deals with the investigation of two types of coreless induction furnaces, one of 60 cycles, the other of 5000 cycles. Nickel was used as test material and the absorption of oxygen by molten nickel was chosen for determining the influence of the frequency on the metallurgical characteristics of the furnaces. Dr. Herty's aluminum method, slightly modified, was found suitable for determining the nickel oxide content in nickel. Also an electrolytic method for determining alumina in nickel was worked out. The solubility-temperature relations for nickel oxide in molten nickel were determined approximately. It was found that the solubility of nickel oxide increases with the temperature. Comparative tests on the rate of oxygen absorption made in a 60 and a 5000-cycle furnace showed that the absorption of nickel oxide in nickel is an increasing function of turbulence, time and temperature. The rate of oxygen pickup in the 60-cycle furnace is about three times as great as in the 5000-cycle furnace. In the 60-cycle furnace the maximum oxygen content of the melt comes close to the saturation limit. Melting under an oxygen-free atmosphere prevents oxidation in both types of furnaces. DISCUSSION (Iloward Scott presiding) H. Scott, East Pittsburgh, Pa.—When Professor Desch was in Pittsburgh recently he mentioned that the induction furnace has practically replaced the crucible furnace in Sheffield except for the carbon tool steels. Dr. Hensel is to be congratulated on the development of analytical methods for determining inclusions and for getting two different methods to agree. F. R. Hesnsel—Recently the purification of molten metals with hydrogen or other suitable gases has become an important issue and a number of patents have been taken out covering gaseous treatments of molten metals. In this connection I wish to call

Jan 1, 1933

By Will Coghill

As the title indicates, this paper treats of the degree of liberation of minerals after grinding. To obtain the supporting data a "tool" not commonly used by metallurgists has been employed. It is the "heavy solution." The advantages gained through its use are shown. Actual ores were employed in order to make the study concrete. The selection was somewhat incidental and happened to embrace the red iron ores of Alabama. So, any reader interested in these ores will find some of their properties described. The red ores constituted the material examined and a somewhat new adaptation of heavy solutions was the tool of examination. If either the ores or the tool interest the reader these notes may be of some value. The writer's chief interest was in the rate of liberation of locked grains. Ores are generally ground preparatory to concentration and as long as the concentrators make suitable products the effectiveness of the grinding is likely to be unquestioned. But when suitable products are difficult to make, an investigation becomes imperative. In such a case a dissection of the ore might be made to find the cause of the trouble. Such a condition of unsuitable products exists in the low-grade red iron ores of Alabama. They are difficult to concentrate. To be sure it might be said that the concentration of iron ores is a new thing and that the ore-dressing methods are undeveloped, but a glance at the industry reveals an abundance of methods and devices for almost all imaginable conditions. Concentrating machinery has not taken a part in this investigation; the use of it would have been only machinery testing, and should never precede the ore testing which consists of such methods as herein outlined. When the properties of the ores have been gleaned the machinery may be used more effectively.

Jan 12, 1926

By S. G. Dixit, A. K. Biswas

The flotation and adsorption behavior of ilmenite, monazite and zircon have been studied with sodium oleate as the collector and pH as the principal variable. The maxima in the flotation and adsorption properties of any of the above minerals fall within similar pH ranges. The bell shaped pH versus adsorption magnitude (r) curve is explained on the basis of collector concentration (Co and the concentration of hydroxyl ion (COH-) acting as the depressant. An equation of the type: 1 =KiCor~K2 Coh-/Coi-is proposed to account for the experimental data. The beach sand deposits along the sea coast in Southern India contain ilmenite, monazite, zircon, rutile and sillimanite as valuable minerals while quartz, garnet, shells and traces of hornblende form the gangue. A typical composition of the deposits is reported to be as follows:' Ilmenite 75%, Zircon 4-6%, Rutile 3-4%, Monazite 2 - 4%, Garnet 2 - 5% and the rest 8 -10%. Selective flotation of beach sand constituents has been reported by many workers.2-4 The fatty acid soaps have been invariably used as collectors. It is seen that all the valuable constituents of the beach sand are efficiently floated by soap collectors such as sodium oleate. In order to selectively float the beach sand constituents, it is necessary to use some depressants such as sodium silicate.3 The physicochemical parameters that govern the flotation of these minerals are yet to be studied in detail. In the present article, the findings on the parallel studies on the flotation and adsorption of the systems — ilmenite-sodium oleate, monazite-sodium oleate and zircon-sodium oleate — are being reported. In these correlative studies on adsorption and flotation of beach sand minerals, ilmenite (FeTiO3), monazite (Ce, Dy, Nd) PO4 and zircon (ZrSiO,) have been selected because they represent three important

Jan 1, 1970

By W. J. Uren, Charles R. Kuzell

The industries engaged in winning minerals from the earth, because of their widespread dissemination, are faced with perhaps as wide a variety of labor-management problems as may be found in any other broad sphere of productive activity. Those problems are continually increasing in volume and complexity, and management has become aware of their growing importance. For the past quarter century at least, labor-management problems have largely been union-management problems. During this period tremendous assistance has been given labor unions through legislation and administrative and political action. In the United States, legislation favorable to unions has come about in the form of the now defunct National Industrial Recovery Act; the Wagner Act, most of which has been carried forward in the Taft-Hartley Act and the Landrum-Griffin Act; the Norris-La Guardia Act, the Wage and Hour Law, the Walsh-Healey Act, and others. The result has been to transfer from the hands of management to those who direct the affairs of the unions a large share of control over the industry and to hamper in many ways the remaining control left to management. In the United States there are many examples of the power of unions to injure whole industries seriously without regard to the interests of management, the employes, or the public. During 1958 and 1959 revelations of corruption and coercion in labor unions made before the McClellan Committee of the U. S. Senate generated considerable public sentiment in favor of legislation to protect the interests of employes and the public. However, the resulting legislation, the Labor-Management Reporting and Disclosure Act of 1959 (Landrum-Griffin Act), demonstrated quite clearly that the political power of the labor union leaders was adequate to prevent adoption of effective measures in this field.

Jan 1, 1964

By Eugene Coste

ALTHOUGH some of the observers who first paid especial attention to the occurrences of oil and gas in the strata (such as Hunt in 1859, Andrews in 1861, Winchell in 1865, Mendelejeff in 1876, Höfer in 1876, Minshall in 1881, and I. C. White in 1883) seem to have been impressed with the fact that oil and gas deposits were connected with the disturbances in the rocks caused by their upheaval,1 yet, with the exception of Mendelejeff, and possibly Andrews, these observers do not appear to have understood what is really the one essential factor in the occurrence of oil and gas in the strata: viz., the faulting, uplifting, fracturing, fissuring, and jointing always accompanying even slight rock disturbances, and in certain districts (petroliferous provinces)2 allowing solfataric hydrocarbon emanations to force their way up from the interior and to reach and impregnate the porous portions of sediments subjected to the disturbances. Instead of this simple explanation to account for the observed connection between petroleum deposits and rock disturbances, most of the observers mentioned above, and many others who have followed them on the name lines since, have entirely reversed the problem. To them, instead of the dissemination of gases from fissures into the sediments, it presented the accumulation and concentration, according to anticlinal or other geologic structures, of oil and gas originally present throughout the whole mass of the strata where they were produced by the decomposition or distillation of organic remains. Whether this important problem involves accumulation from sources within the oil-bearing strata themselves, or infiltration and dissemination from outside sources, may be easily determined if all preconceived ideas are put aside and the established facts only are considered.

Jan 9, 1914

By D. Coutsouradis, L. Habraken, P. Nicolaides

The TTT curves of 0.1 pct C, 13 pct Cr steels containing up to 12 pct Co have been determined in order to establish whether the effect of cobalt is similar to that observed m plain carbon steels. It is shown that cobalt increases the incubation time and decreases the transformation rate, though not in an uniform way. The bainitic transfornation is displaced to lower temperature and overlaps partially the martensitic zone. ThE effect of cobalt on the transformation of a plain carbon austenite has been studied by many investi-gators.'-3 It was shown that cobalt displaces the TTT curves to shorter times and diminishes the harden-ability. The interpretations given for this effect of cobalt are conflicting. According to E. Houdremont,4 cobalt increases the transformation rate of austenite because it increases the diffusion of carbon as shown in the experiments of E. Houdremont and H.Schrader,' R.Smoluchowski,5 and M. Blanter.6 On the other hand, M. Hawites and R. Mehl3 deny on the basis of their own experiments any effect of cobalt on the diffusion of carbon and they assume that an explanation should be found in an eventual effect of cobalt on the mechanism of nucleation and growth of pearlite. W. C. Hagel, G. M. Pound, and R. F. Mehl7 have shown by calorimetric measurements that cobalt increases the free energy of the austenite-pearlite transformation in an eutectoid steel and this result explains qualitatively the observed effect of cobalt on the rate of nucleation and growth of pearlite. The purpose of this research was to see by determination of TTT curves, if this same effect exists in 13 pct Cr steels. EXPERIMENTAL PROCEDURES The preparation of the alloys was carried out in an

Jan 1, 1960

By W. E. Keck, Paul Jasberg

TheRe is a considerable tonnage of iron ore in the Menominee Range of Michigan that is unsalable only because it has too large a content of sulphur. Beneficiation of such ore is economically desirable, as a relatively large quantity of finished concentrate would be obtained (deleterious sulphur mineral content being generally less than 5 per cent) and because large blocks of such ore have been developed incidentally during search for low-sulphur ore. Research on the flotation beneficiation of these high-sulphur ores consisted of: (1) a study of the flotative properties of the principal mincrals in a nearly pure state, (2) flotation of synthetic mixtures of these pure minerals and (3) application of this experimental information to samples of the ores. Gypsum in iron ores is extremely deleterious; but when sufficiently free from impurities it is a valuable commodity. In 1934, the United States produced 1,500,000 tons of calcined and uncalcined gypsum valued at $13,700,0001. Of this quantity and value, Michigan produced approximately 19 per cent1. Thus this investigation may also prove to be of interest in connection with the gypsum industry if minerals separation, such as flotation, becomes necessary in the future processing of gypsum. Data on the flotative properties of gypsum would also be of interest to the science of flotation because such information has been extremely limited. The technical literature reveals one reference to the flotation of gypsum, in which was discussed the use of the mineral, with several others, to determine the relation between the floatability of minerals and the pH of the flotation solution2. This investigation necessarily was not comprehensive in regard to gypsum, but it did show that the mineral could be floated with oleic acid under varying pH conditions.

Jan 1, 1938

By W. E. Keck, Paul Jasberg

TheRe is a considerable tonnage of iron ore in the Menominee Range of Michigan that is unsalable only because it has too large a content of sulphur. Beneficiation of such ore is economically desirable, as a relatively large quantity of finished concentrate would be obtained (deleterious sulphur mineral content being generally less than 5 per cent) and because large blocks of such ore have been developed incidentally during search for low-sulphur ore. Research on the flotation beneficiation of these high-sulphur ores consisted of: (1) a study of the flotative properties of the principal mincrals in a nearly pure state, (2) flotation of synthetic mixtures of these pure minerals and (3) application of this experimental information to samples of the ores. Gypsum in iron ores is extremely deleterious; but when sufficiently free from impurities it is a valuable commodity. In 1934, the United States produced 1,500,000 tons of calcined and uncalcined gypsum valued at $13,700,0001. Of this quantity and value, Michigan produced approximately 19 per cent1. Thus this investigation may also prove to be of interest in connection with the gypsum industry if minerals separation, such as flotation, becomes necessary in the future processing of gypsum. Data on the flotative properties of gypsum would also be of interest to the science of flotation because such information has been extremely limited. The technical literature reveals one reference to the flotation of gypsum, in which was discussed the use of the mineral, with several others, to determine the relation between the floatability of minerals and the pH of the flotation solution2. This investigation necessarily was not comprehensive in regard to gypsum, but it did show that the mineral could be floated with oleic acid under varying pH conditions.

Jan 1, 1938

By Lester Tarnopol, Ralph Hultgren

A considerable interest in the subject of superlattices has been manifested by many papers and reviews that have recently appeared, both in physical and metallurgical publications. This interest is due largely to the apparent simplicity of the ordering process, which permits the explanation of many phenomena on the basis of elementary theory. Moreover, ordering may cause important changes in the physical properties of alloys. In this paper, we shall discuss the causes of superlattices in terms of simple properties of the elements that give rise to them, together with a series of experiments performed to test our conclusions. Evidence is presented that in some cases the process of ordering is more complex than might be supposed. While the different species of atoms are usually found in random positions in alloy lattices, in some cases unlike atoms tend to be nearest neighbors. Bethe's1 "order of neighbors" is a statistical measure of thib tendency. At suitable compositions it is possible for atoms in large regions to be regularly arranged, which causes superlattice lines to appear. in X-ray diffraction patterns. Bragg and Williams2 haw dealt with this "long-distance order" in their fundamental work 011 superlattices. Excellent discussions of superlattices are to be found in current reviews TheRmodynamic Considerations Thcrmal vibration tends to destroy order. The magnitude of the effect can be determined from the entropy of mixing, which is calculate from first principles. Since the ordered state has the lower entropy, it must also have a lower internal energy to be stable at any temperature. The difference in internal energy determines the critical temperature at which long-distance order disappears. According to the, theory of Bragg and Williams,~

Jan 1, 1939

By Lester Tarnopol, Ralph Hultgren

A considerable interest in the subject of superlattices has been manifested by many papers and reviews that have recently appeared, both in physical and metallurgical publications. This interest is due largely to the apparent simplicity of the ordering process, which permits the explanation of many phenomena on the basis of elementary theory. Moreover, ordering may cause important changes in the physical properties of alloys. In this paper, we shall discuss the causes of superlattices in terms of simple properties of the elements that give rise to them, together with a series of experiments performed to test our conclusions. Evidence is presented that in some cases the process of ordering is more complex than might be supposed. While the different species of atoms are usually found in random positions in alloy lattices, in some cases unlike atoms tend to be nearest neighbors. Bethe's1 "order of neighbors" is a statistical measure of thib tendency. At suitable compositions it is possible for atoms in large regions to be regularly arranged, which causes superlattice lines to appear. in X-ray diffraction patterns. Bragg and Williams2 haw dealt with this "long-distance order" in their fundamental work 011 superlattices. Excellent discussions of superlattices are to be found in current reviews TheRmodynamic Considerations Thcrmal vibration tends to destroy order. The magnitude of the effect can be determined from the entropy of mixing, which is calculate from first principles. Since the ordered state has the lower entropy, it must also have a lower internal energy to be stable at any temperature. The difference in internal energy determines the critical temperature at which long-distance order disappears. According to the, theory of Bragg and Williams,~

Jan 1, 1939