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By Dr. O’Neil Thomas J., Donald W. Gentry

Pure gold was hidden in the quartz, they said, 'Twas proved by dreams and signs, and rods divining, By chemic tests, and spirits of the dead, In fact by everything-except by mining. " from R.E. White, "The Mining Town," Alta California, August 18,1873 Textbooks in mining engineering have traditionally covered ore reserve estimation and mine valuation in a single volume. Indeed, Examination and Valuation of Mineral Property by R. D. Parks (1957), having been the standard of the profession for over 20 years, is a classic example. However, the state of knowledge in these two fields has grown tremendously. Most mining engineering curricula now cover these topics in separate courses, and in practice, these tasks are usually performed by different individuals. Thus, this trend now suggests the need for separate, specialized publications rather than a single volume for both topics. Because of the separate development of the science of ore reserve estimation, it is important to state at the beginning what this chapter does not cover. It does not address in detail the design of sampling programs, sampling methods, or the processing of samples or sample data compilation. There are a number of suitable references available on these topics, including Peters (1978), Gy (1979), as well as the previously cited book by Parks. Furthermore, this chapter does not cover in any substantial detail either the traditional methods for using sample data to calculate ore reserves or the more recently developed geostatistical methods. The traditional methods are thoroughly covered by Popoff (1966) and more concisely by Barnes (1980). Among the more useful references for statistical applications in ore reserve estimation are Barnes (1980), David (1977), and Clark (1979). A thoughtful review of the entire science and art of ore reserve estimation is provided by King, McMahon, and Bujtor (1982). In spite of the fact that expansion of knowledge now calls for separate books on ore reserve estimation and financial evaluation, neither publication can ignore the important interrelationships between the two fields. In regard to this text, the unique and crucial role of ore reserves can not be omitted entirely; however, the field is now simply too extensive to treat here in any comprehensive manner.

Jan 1, 1984

By W. W. Stephens, W. J. Kroll, H. P. Holmes

THE only two methods for producing commercial quantities of malleable zirconium, up to now, have been using magnesium reduction of the anhydrous chloride under a neutral gas, and using purification of raw zirconium by the iodide dissociation method on a hot filament. The purity of the metal obtained by the latter process is about the same as that resulting from the chloride reduction, with the exception of the oxygen content, which may be about 0.05 pct lower in the iodide metal. Even traces of oxygen have a strong hardening effect on zirconium. Since, in the iodide process, the impurities, Si, Al, Fe, Ni, and Mg in the raw zirconium used, are carried over, it would appear uneconomical to use this method of refining solely to eliminate the traces of oxygen, unless very soft metal is desired. One important step to improve the iodide method, namely, dissociating pure iodide made from carbide and recycling the iodine, which would change this refining process into a method for extracting zirconium from the ore, has not yet been made. The Bureau of Mines, by using the chloride reduction, wanted to produce quantities of a reasonably pure and malleable metal at low cost for large-scale industrial use. This aim has been achieved, and a pilot plant permitting production of 600 lb of malleable zirconium per week will be described (fig. 1). Briefly, the Bureau of Mines process consists of reducing purified gaseous anhydrous zirconium chloride with fused magnesium under a noble-gas atmosphere. The reaction product, magnesium chloride, and any excess magnesium metal present are removed from the sponge zirconium in the next step by fusion and evaporation in a good vacuum at about 925°C. In this process, care is taken to keep air out of contact with the hot metal, which otherwise would contaminate the product with oxygen and nitrogen. Both these impurities embrittle zirconium even when present in an amount as low as 0.1 pct. A number of previous reports1-3 describe the method and the various improvements that finally led to a workable process. The major steps made were the production of large quantities of carbide, which is the raw material for producing the chloride, its chlorination with reasonable efficiencies, and the elimination of iron trichloride contained in the raw chloride, as well as that of the zirconium oxide which is always present in this product. The physical nature of the anhydrous chloride, which sublimes at 331°C at atmospheric pressure and melts at 420°C under a pressure of 25 atm, made it necessary to provide a special safety device on the purification and reduction vessels in the form of a lead-alloy seal, permitting escape of excess gases if pressure tended to build up. The main difficulties encountered in the reduction and in the following step, salt separation in a vacuum at elevated temperature, were caused by the material from which the reaction pot was constructed—iron. This metal reacts with zirconium at about 940°C with formation of a eutectic. The last step, salt separation by evaporation of the magnesium and magnesium chloride in a vacuum, is quite unconventional and has not been used before on such a scale. It is only due to the improved construction of high-vacuum pumps, especially oil-diffusion pumps, that such a method could be used. The various steps of the Bureau of Mines process, as described in the general outline above, may be summarized as follows: (1) production of the carbide, (2) chlorination of the carbide, (3) purification of the raw chloride, (4) reduction of the pure chloride with fused magnesium, (5) separation of excess magnesium and magnesium chloride in vacuum at elevated temperature, and (6) melting of the sponge obtained. Production of Carbide The arc furnace, described in a previous report,' was improved both to reduce the graphite consumption caused by the burning of the bottom plates and to concentrate the heat in order to obtain better power efficiency. This was achieved by providing the bottom with graphite plates entirely embedded in refractory bricks, the contact with the current being made with three water-cooled copper plugs. Figs. 2 and 3 show the arrangement. The crucible, made

Jan 1, 1951

By C. E. Wood, E. P. Barrett, T. L. Joseph

The invention of the Bessemer converter process in 1856 added great impetus to the manufacture of steel and is one of the outstanding contributions to process metallurgy. Although the process of refining pig iron by passing air through the molten metal bears the name of Henry Bessemer, it should be mentioned in passing that William Kelley of Eddysville, Ky., worked on the process as early as 1847. Kelley was granted a patent on the process in 1857, inasmuch as he was able to prove priority in discovery.' After considerable litigation in 1865 the respective interests of Kelley and Bessemer were combined. On Sept. 10, 1856, Robert Mushet of England obtained his first patent on the application of manganese to cast steel. Mushet anticipated trouble in purifying iron by passing currents of air through it: His patent specified that steel made in this way often contained flaws and was red short or cold short. Mushet understood the refining of pig iron into steel well enough to realize the difficulties likely to be cncountered from oxidation of the iron. Mushet was not only an inventor; he was also an investigator. He understood the principle of selective oxidation which takes place in the converter process, and he realized therefore that the remedy for over-oxidation was attainable if a suitable metal could be found at a reasonable cost and in sufficient quantities. His first experiments were made in small crucibles holding a few ounces of metal. Later his work was conducted on a larger scale and with complete success. Manganese had been used in making steel a quarter of a century before the converter

Jan 1, 1927

By Harrison R. Cooper

With problems of diminishing ore grades and increasing cost of facilities, the mineral industry is acutely aware of the needs for improving beneficiation processes. Industry and universities are directing intensive technical effort to develop- ment of techniques with potential for using digital computers in automation and process analysis. The main problem of early attempts at on-line computer process control methods was that of economics. Now, with new advances in analysis and modeling making practical application economically important, it appears that minerals beneficiation is on the threshold of a significant jump in operating technology. In reviewing this work, particular note was taken of research and development applied to fundamental processes and the significant areas of effort where operations research techniques are used for process applications leading to the current state-of-the-art. Development of data automation and on-line control methods for process industries is deferred to the next section of this volume. This section deals with computer-facilitated mathematical-modeling development and reviews this work in conjunction with associated prior fundamental research leading to development of the methods. Flotation The 1960 state-of -the -art in flotation modeling was com- piled by Arbiter and Harris in the volume, 50th Anniversary of Froth Flotation, edited by Fuerstenau1. Many workers in the field of flotation initiated their research through flotation models, and this effort has led to use of simulation and operations re search methods employing computer techniques to facilitate advance of this work. The flotation model of Imaizumi and Inoue, published with supporting data in 1962, was expanded in 1968 with the objective of developing a basis for process automation.2,3 The fundamental work of Woodburn and Loveday in 1965 has led to techniques applicable to flotation circuit design optimization.4 This analysis is described in this volume by Woodburn in conjunction with King, Buchalter, and Piper. Niemi5,6 derived models for dynamics of a flotation circuit which were employed in developing a model describing

Jan 1, 1969

By Milton E. Wadsworth, John N. Ong, W. Martin Fassell

The temperature and oxygen concentration dependence on the reaction of sphalerite in oxygen at pressures from 6 to 640 mm Hg have been investigated in the temperature range 700° to 870°C. Sphalerite has been found to oxidize linearly over this entire temperature and pressure range. At higher rates, considerable self-heating was observed. The dependence of the oxidation rate on the oxygen concentration may be expressed by: Rate = k' where k' is the specific rate constant and 0 = K1[O2]/(1 + KI[O2]), where K1 is the equilibrium rate constant for the adsorption of oxygen on sphalerite. Values of the activation energy and the enthalpy of adsorption were found to be 60.3 and —59.6 kcal per mol, respectively. Data have been presented that indicate conditions under which either a sulphatizing or an oxidizing roast may be obtained. ROASTING processes have been employed in the metallurgy of a great number of basic metals in use today. Until recently, however, little attempt has been made to deduce the fundamental mechanism by which oxidation takes place. Structural changes upon oxidation have been investigated1 = and thorough work has been performed with regard to the reaction products and the thermodynamics of the oxidation reactions. The objective of this investigation was to determine the rate of oxidation of sphalerite and to apply the absolute reaction rate theory in the theoretilcal interpretation of the experimental results." "O Description of Apparatus The apparatus contains the following features: 1—a furnace with gas system, 2—an autographic weighing system, and 3—a temperature control system. Furnace With Gas System—The furnace was mounted by a yoke on each end and was free to travel up and down on steel guide rods, permitting the introduction and removal of samples from the apparatus with minimum difficulty. The furnace was heated by three sections of Kanthal wire wound externally on a zirconia tube and insulated with Fiber-frax. Pure gases or mixtures of gases were introduced into the lower end of the furnace through two flowmeters, a mixing chamber, and a gas-tight sparger, Fig. 1. The gaseous products of the reaction and the unused gases were prevented from escaping to the atmosphere by maintaining a small negative pressure on the system. This procedure permitted air from the outside to enter through the small an-nulus around the quartz suspension fiber and prevented the escape of the internal gases. Autographic Weighing System—The autographic weighing system consisted of an adapted gold balance, a photoelectric circuit, and a weight recorder, Fig. 2. The sample was suspended from one end of the balance beam by means of a platinum chain outside the furnace and a long thin quartz fiber on the inside of the furnace. On the other end of the balance beam, the necessary weights were added to counterbalance the sample. In addition, a calibrated chain was added to the balance which was linked directly to the weight recording unit. Control was effected by means of a photoelectric circuit." A parallel beam of light from a strong source was directed onto a small front-surfaced aluminum mirror mounted in the middle of the balance beam and then to a front-surfaced mirror mounted on the ceiling of the room. The beam was then reflected onto a front-surfaced right prism at a distance of 9 ft from the balance

Jan 1, 1957

By J. E. McDonald, J. G. Eberhart

A model is discussed from which the work of adhcslon .tor liquid transition metals on aluminum oxide surfaces can he calculated, A close-packed (00011 oxygen surface on A12O3 is assumed with two different types of surface sites: one type involving metal-oxygen bonds and the other man der Waals into actions. The work of adhesion is thus expressed as the sum of these two bonsding free energies. Calculated works of adhesion for nickel, titanium, chromium, and zirconium on sapphire agree well with the experimentally determined quantities. The model is extentled to the calculation of the work of adhesion and shear stress required to remove a thin metal film from a sapphire substrate and is in good agreement with experimental values. The obsewed dependence of the work of adhesion on the free energy of oxide formation of the metal is shown to also provide an interpretation of the tittle dependence of thin-film adhesion. THIS paper presents a model for the type of bonding which occurs across a metal-A12O3 interface. The model is used to explain the results of two types of experiments in which such an interface exists: 1) the adhesion of thin metal films on Al2O3 substrates and 2) the wetting of A12O3 by liquid metal drops. The adhesion of thin films to various substrates has been the subject of a variety of investigations.'-' Benjamin and weaver3 and Bowie,6 using the scratch test developed by Heavens,10 studied the adhesion of metallic films to glass substrates. Their observations for noble-metal film adhesion agree well with an adhesion model involving a van der Waals type of bonding between the film and the substrate. For films of metals whose free energy of oxide formation. ?F°f, has a negative value. Benjamin and weaver3 and Bowie6 found a time-dependent adhesion with an initial value that can be interpreted in terms of van der Waals interactions but a larger terminal value which was related to ?F°f, Karnow-sky and Estill7 deposited films on sapphire at elevated temperatures and noticed no time dependence of film adhesion but a similar correlation with ?F°f. Because of the kinetic problems associated with thin-film adhesion it is desirable to examine adhesion in an equilibrium system. The wetting behavior of liquid-metal drops on Al2O3 provides such a system. Systems of this metal-ceramic type have been studied extensively.11 Humenik and Kingeryl2 have measured the wetting of A12O3 (and other substrates) by several metals and have pointed out that the wetting ability of these metals increases with increasing values of -?F°f. It is thus seen that thin-film adhesion and metal wetting on A12O3 are both related to the tendency of the metal to react with the surface oxide ions of the Al2O3 substrate and, because of this, both phenomena should be explainable by an appropriate model for the metal-Al2O3 interfacial bonding. In the sections that follow, wetting and adhesion data on A2O3 are reviewed and a model is presented by which these phenomena can be interpreted. ANALYSIS OF WETTING EXPERIMENTS In an equilibrium system involving a liquid-metal drop on a solid Al2O3 substrate, the work of adhesion, WAD, is defined by the Dupre, equation as WAD = ?s + ?L -?sL [1] where ?s and ?L are the surface free energies of the solid substrate and the liquid drop, respectively, and ?sL is the interfacial free energy. The work of adhesion is the work required to separate a unit area of the solid-liquid interface into two surfaces. The work of adhesion is usually determined from a sessile-drop experiment in which yL and the contact angle, ?, are measured. The Young-Dupr6 equation is then used to calculate WAD Wad = ?L (1+ cos ?) [2] The literature of this subject has been examined and Table I shows work of adhesion data for various liquid metals as measured on A12O3 substrates. The standard free energy of oxide formation of the metal at the temperature of the wetting experiment, ?F°f . is also tabulated in kcal per g-atom of oxygen. The data is grouped according to the gaseous atmos-

Jan 1, 1965

By W. H. Furlonge

WHILE fulfilling professional engagements, my travels over this portion of the Transvaal have been quite extensive—always on horseback however, so that anything like a thorough investigation of the ground passed over has been necessarily impossible; still, the more minute examination of certain small areas, coupled with general observations, has enabled me to form some idea as to the prominent geological features of the country as a whole. Anything like a complete or comprehensive description is indeed out of the question, as there are no proper maps of the country and the facilities for observation are limited. A large plateau, called the "High Veldt," stretches from east to west across the Transvaal. It is generally level, or gently rolling, and has an average elevation of 6000 feet above the sea; it is destitute of timber, and in fact greatly resembles the western prairies of North America. Rock-outcrops are not common in it. It terminates very abruptly to the east and northeast, the descent of 2000 or 3000 feet into the mountainous country that occupies its borders being made in a

Jan 1, 1890

By J. H. Hollomon, L. D. Jaffe

The hardenability concept has become widely used during the last few years for the choice and substitution of steels. Before the work of Grossmann,1 the systems for predicting hardenability from chemical composition could be used only over a narrow range of composition. Grossmann introduced a comprehensive system, which has been effective in calculating the hardenability of most types of moderate or low-alloy steels. However, occasions often arise that require the calculation of the hardenability of high-alloy steels from their chemical compositions. Experimental determinations of the hardenabilities of such steels indicate that the Grossmann system predicts much greater hardenabilities than are realized. The fact that cases do arise in which the Grossmann method does not apply indicates that the fundamental hypothesis of the system may not be generally applicable. It seems advisable to re-examine not only Grossmann's system but also the concept of hardenability itself. Hardenability If steel parts are to possess a martensitic structure after quenching, they must first be austenitized and then cooled through the pearlite and bainite transformation ranges sufficiently rapidly to avoid the formation of pearlite, bainite, and pro-eutectoid products.* If, on cooling, these transformations are avoided, the resulting structure can consist only of martensite (and retained austenite). The hardenability of a steel is measured in terms of the severity of the cooling conditions necessary to avoid the pearlite and bainite transformations. The less rapid is the cooling necessary to prevent the formation of bainite and pearlite, the higher is the hardenability. The pearlite and bainite reactions appear to be differently affected by the alloying elements. Not only is this indicated by the published isothermal transformation data, but recent work by Zener2 affords a rational interpretation of the differing effects of the alloying elements. Manganese,3 for example, appears to decrease the rates of the pearlite and bainite transformations by equal percentages, while molybdenum45 is approximately 10,000 times more effective in retarding the pearlite than in retarding the bainite transformation, on the basis of isothermal measurements. In some steels, the formation of bainite restricts the formation of martensite while

Jan 1, 1947

By L. D. Jaffe, J. H. Hollomon

The hardenability concept has become widely used during the last few years for the choice and substitution of steels. Before the work of Grossmann,1 the systems for predicting hardenability from chemical composition could be used only over a narrow range of composition. Grossmann introduced a comprehensive system, which has been effective in calculating the hardenability of most types of moderate or low-alloy steels. However, occasions often arise that require the calculation of the hardenability of high-alloy steels from their chemical compositions. Experimental determinations of the hardenabilities of such steels indicate that the Grossmann system predicts much greater hardenabilities than are realized. The fact that cases do arise in which the Grossmann method does not apply indicates that the fundamental hypothesis of the system may not be generally applicable. It seems advisable to re-examine not only Grossmann's system but also the concept of hardenability itself. Hardenability If steel parts are to possess a martensitic structure after quenching, they must first be austenitized and then cooled through the pearlite and bainite transformation ranges sufficiently rapidly to avoid the formation of pearlite, bainite, and pro-eutectoid products.* If, on cooling, these transformations are avoided, the resulting structure can consist only of martensite (and retained austenite). The hardenability of a steel is measured in terms of the severity of the cooling conditions necessary to avoid the pearlite and bainite transformations. The less rapid is the cooling necessary to prevent the formation of bainite and pearlite, the higher is the hardenability. The pearlite and bainite reactions appear to be differently affected by the alloying elements. Not only is this indicated by the published isothermal transformation data, but recent work by Zener2 affords a rational interpretation of the differing effects of the alloying elements. Manganese,3 for example, appears to decrease the rates of the pearlite and bainite transformations by equal percentages, while molybdenum45 is approximately 10,000 times more effective in retarding the pearlite than in retarding the bainite transformation, on the basis of isothermal measurements. In some steels, the formation of bainite restricts the formation of martensite while

Jan 1, 1947

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 V. A. Josendal, J. W. Wilson, B. B. Sandiford

Two radioactive tracers have been tested as a means of determining core saturation in multiphase flow studies. Cesium chloride was tried as a water-phase tracer, but complications in its use in low permeability cores resulted from sorption of cesium by the core or water-wet pads. IodoI3'ben-zene proved very satisfactory as an oil-phase tracer. The synthesis of iodobenzene from the sodium iodide as received from Oak Ridge is simple and direct. The tracer is insoluble in water and there was no evidence of sorption by any of the core materials used. use of the method to determine saturation profiles during capillary and dynamic desaturations and relative permeability measurements on oil-water and oil-gas systems is described. Comparisons of the dynamic and capillary methods of relative permeability determination were made using the tracer to check core saturation and saturation distribution. Other experiments are also described in which mobility of the oil phase at various saturations was measured by displacing labeled oil by flowing inactive oil. Similar experiments were made using water labeled with cesium 134. INTRODUCTION To be fundamentally sound. any laboratory method of determining relative permeability must meet, among others, the following requirements: (1) the core saturation between the pressure taps must be uniform, and (2) there must be uniform pressure difference between the phases in the region between the pressure taps. In practice it may eventually be shown that appreciable departure from either or both of these conditions may be permitted without introducing sensible error. but the magnitude of such error remains to be established. There is need then for methods of saturation determina- tion which will determine the saturation profile in a core as well as the overall average saturation given by the gravimetric or material balance methods usually employed. Methods which have received consideration include resistivity, X-ray absorption, gamma ray absorption, neutron diffraction, and radioactive tracers. The resistivity method has use in the determination of profile, but needs checking by independent means.' The X-ray method has been used successfully, but requires elaborate equipment and calibration.23 4 At present gamma ray absorption is practical only for very large cores. The neutron methodo does not appear adaptable to measurement of saturation variations in short cores since it is a scattering method. Russell, Morgan and Muskat' employed radiovanadium in a study of the mobility of interstitial water. Coomber and Tiratsook used radioiodine as an oil-phase tracer and measured profiles in unconsolidated sand packs. ADVANTAGES OF RADIOACTIVITY METHOD A thorough discussion of the theory of radioactive tracers and the technique of using them to study the movement of fluids in sands is given by Coomber and Tiratsoos and need not be detailed here. The method requires less equipment than the X-ray method; the counting problem is similar, but the generation and regulation of the radiation, which is a major problem in the X-ray method, is not required in the radioactivity method. In the X-ray method it is customary to add up to 20 per cent of absorber, usually an iodine compound, to the phase to be labeled. while in the radioactivity method a mere trace is sufficient. A possible disadvantage of the radioactivity method is that a disproportionate amount of the activity comes from the portion of the core nearest the counter, whereas the X-ray gives a true average saturation in the region traversed by the beam. 011 the other hand, this characteristic of the radioactivity method renders it peculiarly adaptable to study of certain types of radial variations in saturation. As with the X-ray method, a tracer may be added to either the oil or water-phase. An oil-phase tracer is more generally useful. however. since it permits work on oil and gas in the

Jan 1, 1952

By Gerhard Derge

THE orientation relationships resulting from allotropic transforma-tions and the formation of segregate structures in metals and alloys have been the subject of the eight earlier papers in this series1. A brief summary of orientation studies has also been given by Sachs2. A survey of these papers discloses that the factors that determine the orientation relationship of a precipitated phase to its parent solid solution, as Well as the outward form and appearance of the new phase, are not completely understood. It is now evident that crystallographically analogous systems, as a rule, exhibit the same type of Widmanstätten figure and orientation relations, so that useful information is not to be expected from examination of a new alloy involving lattice combinations of which the orientation relationships are already known. Therefore, the determina-tion of the relations existing between lattice types that have not already been studied seems to be the most promising mode of attack upon the problem; both of the systems reported in this paper represent new com-binations of lattice types.

Jan 1, 1937

By J. B. Newkirk, A. H. Geisler

INTRODUCTION CERTAIN of the permanent magnet alloys provide ideal systems for the study of the kinetics of the precipitation reaction and the correlation of structure with properties. One such system, Cu-Ni-Fe, was found by Bradley1,2 to exhibit a coherent transition state in the precipitation process analogous to that reported for Al-Cu alloys somewhat earlier.3 The attractiveness of some permanent magnet alloys for study lies in the fact that vertical sections of the ternary phase diagram in certain regions of composition (Fig I) have as their prototype the binary Ni-Au diagram. Alloys of this type decompose into products that have the same crystal lattice type but only slightly different lattice parameters. The advantages that such alloy systems offer for study over the usual in which an intermetallic compound is formed are many: I. Since the precipitate has the same crystal structure as the matrix, complex atomic movements are not required to form the new lattice. 2. Similarly, complex orientation relationships are not involved for both the matrix and the precipitate would be expected to have the same orientation. 3. Small disregistry of the decomposition products at equilibrium (in contrast with Cu-Ag alloys) is conducive to extensive coherent growth in the transient state and thus the transition lattice can be detected by the usual X ray diffraction methods. 4. Finally, the relative quantities of precipitate and depleted matrix can be varied from o to 100 pct* thus permitting wide freedom for the study of the effect of composition on coherent growth and properties. In the Cu-Ni-Fe alloys of appropriate composition, the face-centered cubic precipitate and also the depleted matrix when first formed are coherent with the parent matrix.1,2 The two have the same [ao] parameter as the original matrix but they are both tetragonal; the precipitate has an axial ratio c/a < I while that of the depleted matrix is c/a > I. When coherency is lost they assume the normal face-centered cubic structure with the depleted matrix having a lattice parameter greater than the original matrix and that of the precipitate less. Such a mechanism would also be expected for Cu-Ni-Co alloys because of the similarity in constitution but this had not been demonstrated. The present investigation was conducted on a Cu-Ni-Co alloy. The constitution diagram and magnetic properties of these alloys have been fairly well established 4,5 however, no previous determinations of mechanism of precipitation and no correlation of structure with properties had been made. Thus, an alloy of this system was chosen for a comprehensive investiga-

Jan 1, 1948

IN GATHERING material for this chapter on Yerington and the one to follow on Silver Bell, the A.S.& R. project near Tucson, Arizona, I was fascinated at the way the two stories paralleled each other. For example, here are a few instances: (1) The first copper mining in the Yerington district of Nevada was in the late 1860&apos;s; the first in the Silver Bell area in 1873. (2) Each district was served by a branch railroad about 25 miles long from a main line of the Southern Pacific (by quizzical coincidence); and, in each instance, the railroad was later abandoned and torn up. (3) Each district had a sizable blast-furnace smelter ten or fifteen miles from the principal mines, and in each instance the smelter was later dismantled for junk. (4) Up to 1954, the Yerington district was credited with a production of 100,000,000 lb of copper; the Silver Bell district with 80,000,000 lb. (5) In each district the entire production had come from deposits other than the low-grade ore bodies now being exploited. (6) In each instance, existence of the low-grade deposits of the Porphyry type was recognized in the period circa1910-1914 and a substantial amount of exploratory drilling had been done, on one deposit at Yerington and on two at Silver Bell. (7) In each instance, the properties containing the Porphyry ore were acquired by a strong company (Anaconda Copper Mining Company at Yerington and American Smelt-

Jan 1, 1957

By J. J. Predali, J. M. Cases

J. J. Predali and J. M. Cases (Attachè de Recherche and Charge de Recherche, respectively, Centre de Recherches sur la Valorisation des Minerais, Institut Polytechnique de Nancy, Nancy, France)-The role of CO, in carbonate flotation is one of the parameters of a complex phenomenon: the adsorption of salts of fatty acids onto minerals. The authors therefore must be congratulated for their work. Their experimental results suggest some questions: 1) Recovery with C02, benzoic acid, or HCl, look very similar [(Fig. 1)] to that with the use of air; however, the recovery decreases very slightly (<10%). But in these two kinds of experiments, two parameters are different: the pH which is near 5.8 (with C02) becomes 9.1(without C02) and the concentration of Ca* I x 10-3 mole per 1 (without C02) becomes 1.9 X 10&apos; mole per 1 (without COO. 2) Adsorption experiments (Fig. 2) permit computing the surface coverage 9 which is 7.4% (without C02) and 8% (without CO_.) for an initial concentration of 12 X 10-6 mole per 1 in sodium oleate. It seems doubtful to us that this small variation can produce large increases of the recovery in flotation. 3) It is difficult to correlate adsoption and flotation experiments because they do not seem to have been done with the same size of particles. The concentration needed to obtain 95% recovery (Fig. 1) is about 3.0 X 10_" mole per l, that is, 1.13 X 10-6 mole for about

Jan 1, 1973

By C. F. Smart

SINCE their comparatively recent development, the alloys of cadmium with silver and copper or nickel, and of cadmium with nickel alone, have been used somewhat extensively as liners for connecting rod bearings and main bearings of internal-combustion engines. In applications where, owing to high hearing loads and elevated operating temperatures, the life of hearings made from tin-hale or lead-base alloys has been undesirably short, cadmium alloys have demonstrated considerable advantage. In applications where, because of deflection of the crankshaft or bearing supports, copper-lead bearing metals have resulted in scored shafts, cadmium alloys have been operated successfully. The somewhat serious drawback to these alloys in hearing service has been that they, in common with copper-lead and certain lead alloys, are susceptible to corrosion in the presence of lubricants containing organic acids. These acids may be fatty acids (such as oleic acid) derived from animal or vegetable oils that sometimes have been compounded with engine lubricants, or they may be compounds of an acid nature developed by the oxidation of some petroleum oils under operating conditions. The result of such acid attack on hearings is illustrated by the photograph, Fig. 1. The petroleum oils that are most readily oxidized to a corrosive condition, and the operating conditions under which such oxidation most readily occurs, are now rather well known among the technical organizations of both the petroleum and automotive industries. While means have been developed for inhibiting petroleum oils against such acid formation, the knowledge that this condition may be encountered has been a factor in restricting the wider use of cadmium alloys as engine bearings. It has appeared, therefore, that their value and use would be enhanced if they could be made corrosion-resistant to a degree compatible with the most severe operating requirements. Investigation, undertaken with this in view, indicated that the addition of fractional percentages of the metal indium to the cadmium bearing

Jan 1, 1938

By Ingvar Janelid

DURING the last ten years, in the effort to save manpower and costs, methods of drilling and blasting in Sweden have changed and developed in a revolutionary manner. These developments have been accompanied by extensive alterations in methods of tunneling and in mining technique. Since the end of the 1940&apos;s there has been a 100 pct change-over in Sweden to the use of tungsten carbide tipped drill steel. Both investigations and practical results have shown clearly that a tungsten carbide chisel bit fastened directly on the drill steel is the most economical for Swedish conditions. This applies to drill steel up to the longest size it is practical to handle. In terms of drilling footage, durability of the drill steel and the tungsten carbide bit is generally the same. In this respect, therefore, a detachable bit offers no advantage over integral steel. Transportation of integral steel to the grinding plant, instead of detachable bits only, involves heavier work, but this is counteracted by placing grinding plants closer together or by grinding at the working place itself. The drilling rate with integral steel is higher, the trouble of changing bits is avoided, and the difficulties which always arise with joints are eliminated.

Jan 6, 1954

By G. E. Anderson

The Asientos-Tepezala district is in the north of the State of Aguasca-lientes, about 30 miles north of the city of Aguascalientes, the capital. The district is reached by a standard-gage railway on the west side through the junction, Rincon de Romos, which is on the main line of the National Railways of Mexico from El Paso to Aguscalientes. The terminal is Tepezala. On the east side a narrow gage connects Asientos with the junction, San Gil, on the main line, Asientos to San Luis Potosi. Tepezala on the west side of the Asientos hills is about 2 miles from Asientos on the east side. The area between the two mining centers is separated by a low subdued divide which forms the central part of the hills. The district is in a group of isolated hills surrounded by characteristic bolsón plains. The hills rise above the surrounding plains about 6500 to 10,000 ft.; the highest peak is Alta Mira. The two mining districts lie somewhat upon the flanks of the hills at about the same elevation, 7200 ft. The district is an old one and has been known since early in the 17th Century when the mines were worked by the Franciscan Monks. Their mining operations, which were limited to the oxidized ore above the water level, consisted chiefly in extracting silver from the Santa Francisca vein. To judge from the old workings and the remains of surface plant, the operations were on a large scale. By modern mining operations since about 1900, the various mines of the district have been one of the principal sourees of ore for the smelter located at Aguascalientes. Topography The topographic features of the Asientos hills are largely controlled by the character of the underlying rocks. During the Tertiary period, the entire group of hills was probably covered by extrusive volcanic material in the form of cones and lava flows. The central part of these have since been carried away by erosion, so that remnants have been left along the borders of the hills. These remnants form rather conspicuous peaks,

Jan 1, 1927

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

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 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