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By A. S. Richardson

THe conditions that make necessary the mechanical ventilation of the Butte mines of the Anaconda Copper Mining Go. are due to a number of causes, all of which are incidental to the depth at which mining operations are now carried on, The main object to be accomplished, of course, is the reduction of the temperature and humidity of the air in the working places. Ventilation fans, both surface and underground, have been used for many years, but increasing depth has made the problem much more difficult. Further improvement in both ventilation equipment and methods, therefore, became necessary; and it is the purpose of this paper to describe the work planned and done under the improvement program. The mines of the district have been frequently described in various technical publications, so a description is unnecessary here. From a mine-ventilation viewpoint, compared with coal-mine ventilation systems, the problem is complicated by the fact that the workings to be ventilated are situated on a large number of steeply dipping veins which frequently intersect and are faulted, and also by the fact that the extent, or existence, of orebodies is not definitely known in advance of actual development work. For these reasons ventilation work cannot be planned in advance of actual operations, nor can such regular systems of ventilation as are used in working the more uniform and continuous bodies of coal be developed. When operations are conducted at a normal rate, about 10,000 miners are employed on two shifts, so that about 5000 men will be underground at one time. But as ventilation is necessary to reduce high temperature and humidity due, mainly, to natural causes, the quantity of air per man per minute is not a governing consideration in determining ventilation requirements. Most important among the numerous sources of heat and humidity in the mines are: heat generated during decay of mine timber; heat and humidity given off by mine rock and water; heat generated by oxidation of sulfide minerals; heat given off by electrical equipment; heat generated by mine fires (in certain localities).

Jan 1, 1923

By P. Beardmore, B. W. Howlett, B. D. Lichter, M. B. Bever

The heats of formation at 273°K of the compounds Mg2Ge, Mg2sn, and Mg2b, the heats of fusion and melting points of Mg2Sn and Mg2Pb, and the heats of solution of magnesium, germanium, and lead in liquid tin have been measured. The excess free energies of the liquid alloys and the free energies of formation of magnesium-Group IVB compounds at their melting points and their standard free energies of formation at 298°K have been calculated. The stability and bonding of the compounds are discussed with reference to these properties. Some thermodynatnic aspects of the liquid phases in the systems Mg-Sn and Mg-Pb are also considered. THE compounds of magnesium with the Group TVB elements, silicon, germanium, tin, and lead, have often been considered to constitute a nearly ideal homologous series. In particular, their thermodynamic stability has been assumed to decrease with increasing atomic number of the Group IVB element.' The binary-phase diagrams of the magnesium-Group IVB elements given by Hansen and Anderko2 have the same form. Each system has a single con-gruently melting compound of limited homogeneity range. The structures of these compounds, which have the formula Mg2X, are anti-isomorphous with the calcium fluoride structure. A recent investigation has found evidence of a second compound in the system Mg-Pb.3 The solid compounds Mg2Si, Mg2Ge, and Mg,Sn are semiconductors, while the conductivity of Mg2Pb approaches that of a metallic conductor. This difference suggests that other properties may also show a discontinuity. The investigation reported here is concerned with the thermodynamic properties of magnesium-IVB compounds and particularly their variations with the period of the Group IVB element. The heats of formation at 273°K of the compounds MgzGe, Mg2Sn, and Mg2Pb and the heats of fusion and melting points of Mg2Sn and Mg2Pb have been measured. The results, combined with published data, are interpreted in relation to the stability and the bonding characteristics of the compounds. Some thermodynamic aspects of the liquid phases in the systems Mg-Sn and Mg-Pb are also considered. In the course of the investigation the heats of solution of magnesium, germanium, and lead in liquid tin have been determined. 1) EXPERIMENTAL PROCEDURES 1.1) Samples. Samples of the compounds Mg2Ge, Mg2Sn, and Mg2Pb, supplied by Professor P. Aigrain, Compagnie Générale de Télégraphie Sans Fils, were used in measuring heats of formation, heats of fusion, and melting points. Samples of Mg2Sn and Mg2Pb, supplied by Dr. V. B. Kurfman, Dow Metal Products Co., samples of Mg2Sn, prepared at the Air Force Cambridge Research Laboratories, and samples of MgzPb, prepared in this laboratory, were used for additional measurements of the heats of fusion and the melting points. The samples were stored in evacuated Pyrex capsules or under nonreacting liquids. 1.2) Heats of Formation. The heats of formation at 273°Kof the compounds Mg2Ge, Mg2Sn, and Mg,Pb were measured by tin-solution calorimetry. In this method, samples of the compound and of a mixture of the constituent elements are added alternately from 0°C to a tin-rich bath. The difference between the heat effects, corrected for the change in composition of the bath, is the heat of formation of the compound. Details of the method have been given elsewhere. 4 The bath was maintained at 350°C for the dissolution of the compounds MgzSn and Mg2Pb. Since at this temperature the dissolution of Mg2Ge was too slow, a bath temperature of 400" or 450°C was used with this compound. At least three calorimetric runs, each of approximately six additions, were made with each compound. 1.3) Heats of Solution. The determination of the heats of solution of magnesium, germanium, and lead in tin was included in this investigation because they were not well-established at the time this work was started. To obtain the heat of solution, the difference

Jan 1, 1967

By J. Chipman, T. Fuwa

The effects of various elements on the activity coefficient of carbon in liquid iron have been studied by two experimental methods: 1) equilibration with controlled mixtures of CO and CO2; 2) the solubility of graphite in the melt. Activity coefficient of C is increased by Al, Co, Cu, Ni, P, Si, S, and Srz. It is decreased by Cr, Cb, Mn, Mo, W, and V. THE thermodynamic properties of the iron-carbon binary system have now been fairly well established, although some uncertainty remains with respect to the exact location of some of the phase boundaries. The activity of carbon in ferrite and in austenite has been measured in the classic researches of R. P. smith' while similar measurements by Richardson and ~ennis, and by Rist and chipman3 have established the values of the activity of carbon in liquid iron up to 1760°C. On the other hand, our knowledge of the effects of alloying elements on the activity of carbon in dilute solutions is restricted to Smith's experiments on systems Fe-C-Mn and Fe-C-Si in the austenitic range and to some more recent experiments of schwarzman4 in the a range. In addition there have been a number of determinations of the effects of various elements on the solubility of graphite in liquid iron, and from these the corresponding effect in saturated solution may be obtained. The purpose of the present study was to extend the investigation of the liquid system to include the effects of alloying elements upon the activity coefficient of carbon, principally in dilute solutions. Equilibrium measurements were made on the reaction C + co, = 2 CO (g) The prepared mixture of CO and CO,, diluted with argon, flowed over the surface of the liquid metal which, after several hours' exposure to the gas, was quenched and anqlyzed. As in the earlier experiments, the principal experimental difficulty was in the deposition of carbon on the parts of the furnace at temperatures slightly below that of the metal bath. In order to minimize this difficulty, the ratio (Pco)2 /PCo2 was restricted to values not much higher than 100 atm, and correspondingly the carbon concentration in the metal seldom exceeded 0.30 pct. EXPERIMENTAL METHODS The method and apparatus were essentially the same as used by Rist and Chipman.3 The gaseous mixture consisting of highly purified CO, CO,, and argon, each controlled by a flowmeter, was led into the furnace and passed over the surface of the liquid-iron melt which was heated and stirred by high-frequency induction. One slight modification was made in that a molybdenum susceptor was placed outside the crucible for the sake of uniformity of temperature and to combat the tendency of carbon to precipitate on the crucible wall. Pure alumina crucibles approximately 25 mm ID were used. The charge consisting of about 30 g was made up of electrolytic iron, the alloying element to be added, and enough graphite to supply slightly more or less than the anticipated equilibrium carbon concentration. All metals used were of high purity. Metallic chromium, columbium, and vanadium were from special lots supplied by the Electro Metallurgical Co. Tin, copper, molybdenum, tungsten, cobalt, and nickel were of purest commercial grades. The electrolytic iron, after being cut to the proper size for charging, was prereduced by hydrogen at 850° to 1000°C to remove surface oxidation. The oxygen content of the reduced material was 0.002 pct. This treatment made it easy to control the carbon content of the initial melt. The charge was melted under the gas mixture to be used for the entire run. In some earlier melts the charge was melted under a stream of argon, but in this case some alumina was reduced from the crucible, and the aluminum thus absorbed in the melt was subsequently oxidized with the formation of a solid film of alumina on the surface of the melt. AS another safeguard against film formation, overheating of the bath was carefully avoided. All runs were made at a temperature of 1560°C. Under experimental conditions a charge of pure iron picked up 0.17 pct C in 3 hr and 0.23 pct C in 6 hr under an atmosphere for which the equilibrium concentration of carbon is 0.27. It is clear that the time required to reach equilibrium from an initially carbon-free melt would be very great. For this reason each experiment was started with a melt of known carbon concentration not far above or below the expected equilibrium value, and each melt was held at temperature for a period of at least 5 hr. Under such circumstances it was possible to chart the approach to equilibrium from both high-carbon and low-carbon materials. Temperature was controlled by frequent optical observation and adjustment and the metls were timed in such a way that the final 2 hr occurred during a time when electric power was steady; for example, 2 to 4 pm or after 11 pm. In melts containine volatile metals such as copper, tin, and mangane\e the time of holding was decreased somewhat in

Jan 1, 1960

By H. M. St. John, T. Rynalski, G. K. Eggleston

Maintaining a satisfactory structure in brass and bronze castings has always been a foundry problem of great practical importance. While metallurgists and scientific investigators have not entirely ignored this matter, it has received less of their attention than has been given to iron, steel and the wrought copper and aluminum alloys. Investigation in this field has probably been discouraged to some extent by the complicated nature of the alloys involved. Hundreds of alloys are in more or less common use, most of them containing copper, zinc, lead and tin in widely varying proportions. They also contain appreciable percentages of iron and antimony as impurities, and often phosphorus, which has been added as a deoxidizer and fluidifier. Small amounts of sulfur are usually present. It is not uncommon to find nickel, sometimes in rather substantial quantities. Traces of other metals are frequently present. So complicated and variable a mixture obviously offers difficulties in any investigation of the various factors that influence the structure and other properties of the casting. Incipient Shrinkage Bolton and Weigandl have called attention to a type of structure characterized by intercrystalline fissures and large dendritic crystals which are frequently tarnished to an orange or reddish brown color. This intercrystalline porosity they term "incipient shrinkage" and attribute to the presence of carbon monoxide in the atmosphere under which the metal was melted. The defective structure to which Bolton and Weigand refer has become a brass-foundry problem of major importance, because it occurs with distressing frequency in leaded brasses and bronzes when these are melted in a neutral or reducing atmosphere. Since the electric furnaces, now coming into general use in brass foundries, normally operate with such an atmosphere and, in fact, depend upon it in part

Jan 1, 1930

By A. L. Engel

STRICTLY speaking, ore-dressing does not commence until after the ore is in the mill bins, but where complex ores are treated and their minerals separated to make the best commercial concentrate with the lowest economical tailing, ore-dressing problems begin and often center in the mine itself. This does not refer to the grade of the ore, but rather to the frequent condition in which metallurgical results radically different from customary are obtained because of changes in the character of the ore treated. Different varieties of ore can usually be identified as coming from well-defined depths or zones in the mine, or from known sections of the orebody. Varying degrees of alteration of the ore, inclusions of harmful gangue material, or variations in the quantities of component metallic minerals are often causes of temporarily bad metallurgical results in otherwise successfully operated plants, especially those employing differential flotation to. recover several valuable minerals contained in the ore.

Jan 1, 1931

By H. L. Teicliman, E. M. Sipprelle

ENACTMENT of Public Law 290 by the 78th Congress authorized the U. S. Department of the Interior, Bureau of Mines, to conduct an experimental program to develop the technology for obtaining oil from oil shale. In adopting and later extending this legislation, the Congress recognized the impending necessity of supplementing ground petroleum reserves with synthetic fuels. Under the provisions of this legislation, the Bureau of Mines, among other things, was charged with the responsibility of developing mining techniques, methods, and equipment for mining the oil shales of the Green River formation of Colorado, Utah, and Wyoming.

Jan 1, 1950

By H. Rush Spedden, A. M. Gaudin

IN the belief that a critical study of its operating problems might be a sound investment, the Cuban American Manganese Corporation initiated an ore-treatment research in cooperation with the Massachusetts Institute of Technology One of the early objectives of this research naturally became the relationship of the microscopy of the Cuban ores of the Corporation to their flotation treatment The operations in Cuba have already been described by F S Norcross, Jr 7 and the laboratory study of manganese oxide flotation goes back a number of years 4 Broadly speaking, the difficulties encountered in the flotation of manganese ores are that the consumption of reagents is extremely high, the concentrate contains more silica than is desirable and the tailing losses are relatively high An appreciable betterment on any of these scores would achieve a definite betterment in costs, quantity of minable ores, and quality of product The microscope study discussed in this paper was made on samples from the Quinto mine, from the Ponupo mine, and from mill products at various stages of passage of the ore through the mill The writers have had access to Company records and in particular to the petrographic studies made on thin sections of ore by the late Professors R J Colony and Philip Krieger, of Columbia University They acknowledge their debt to both of these men for the help derived from the reports Manganese oxides are black, friable, smudging It is therefore, very difficult to judge operations by inspection The mineralogy of manganese compounds seems to be confused, and the authors believe that many more minerals have been described than actually exist Much of this difficulty is due to the prevalence of the structural conditions that will be discussed further in this paper, namely, the porosity and the friability of the ores, and the extremely intimate association of minute manganifeous mineral crystals with impurities of various sorts By all odds the most important manganese mineral in Cuba is the one that in this paper is called "psilomelane " The name "psilomelane" has been used in so many different ways that the choice of it for this ore may not be approved by all However, it seems to be the best under the circumstances This mineral accounts for about 97 per cent of the manganese in the ores of the Quinto and Ponupo mines and in the mill feed The remaining odd 3 per cent consists mostly of pyrolusite together with minor amounts of other manganese oxide minerals DESCRIPTION OF PSILOMELANE Aggregate Structure In grains or lumps, psilomelane has a characteristic fibrous appearance and seems

Jan 1, 1942

By H. S. George

A method of illumination that enhances the value of microscopic study of opaque materials, as in metallography. By simulating natural lighting, structures. That possess relief are given a natural appearance. An example is included of the revelation of a hitherto invisible microconstituent. Erroneous interpretation is avoided. For example, etching figures in ferrite, heretofore considered to be pits, are revealed as pyramids, standing in bas-relief. Suggestions on technique are given, for, while the method is obvious, practice and attention to detail are requisite. ON one occasion when it seemed desirable to reveal under the microscope not only the metallic structure of an alloy, but certain small non-metallic inclusions, that are ordinarily obliterated by etching, it was discovered that, by partly eclipsing the illuminating pencil of light rays, the residual light was thrown on the object from one side and the structure was brought out in relief. At the same time, the non-metallic inclusions were retained in clear view. In this first demonstration of lighting obliquely through the objective a card was thrust part way into the light beam between the arc iris, and the light filter; the shadow of the card on the filter served to locate its position. Next several stiff-paper disks of various diameters were mounted on flexible wires some plasticine on the other end of the wires made it easy to adjust and maintain a disk at any desired position in the light beam. To facilitate manipulation, an assortment of disks, was mounted on a wheel, as shown in Fig. 1. The purpose of partly eclipsing the light beam was discussed in an earlier paper.1 There it was pointed out that the usual methods of illuminating opaque objects for microscopic examination lend an, un-natural appearance to, the view, while the new method, which has been termed conical illumination, revels the true relationship of constituents by simulating natural lighting.

Jan 3, 1924

By John T. Eash, Clair Upthegrove

During recent years nickel has had an increasingly important role as an alloying element in the copper-tin bronzes. Nickel additions not only produce better casting alloys but also make alloys whose properties can be varied by precipitation hardening; thus leading to increased commercial application of copper-nickel-tin alloys. Recent investigations have indicated a decrease in the solubility of tin in the alpha phase as the annealing temperature is lowered and as the nickel content is increased within certain limits. A further change caused by the nickel additions is produced in the excess phase of the copper-tin bronzes. The alpha plus delta eutectoid is replaced by a clear precipitated constituent in the alloys containing up to 15 per cent tin and not less than 1 per cent nickel. This paper has a dual purpose. The first is to present a new determination of the alpha-phase boundary in alloys containing from 0 to 20 per cent nickel, together with the liquidus and solidus temperatures above that field. The second purpose is to give the equilibrium conditions existing in alloys exceeding the alpha phase containing up to 31 per cent tin and 5 per cent nickel, so that the disappearance of the alpha plus delta eutectoid constituent may be explained. After considering the earlier investigations of the related alloy systems and the experimental procedure used in this investigation, the alloys will be discussed in groups as separate quasibinary systems containing constant amounts of nickel. The systems considered contain 0, 1, 2, 3, 5, 10 and 20 per cent nickel. The straight copper-tin system was reinvesti-gated in order to establish a foundation on which to build the remaining material. The 1 per cent nickel alloys studied give the relations existing in the region of the eutectoid transformation between the copper-tin system and the 2 per cent nickel copper-tin system which has been investigated in detail. The thorough examination of the latter system was made since 2 per cent of nickel is representative of the commercial additions to the cast bronzes and also because it is sufficient to produce

Jan 1, 1933

By Eugene S. Machlin

A classical theory of solid solutions involving neavest-nergkbor intevactions with both central and linked-central forces between atoms has been developed. It has been found that the theory, where it can be checked quantitatively, is in ageement with experiment. The theory encompasses a description of many diverse pkenomena, such as antiphase shift structures, size effect, relative stabilities of various solutions, lattice para,neters, and order-disorder transitions. In particulav. a quantitative prediction not involving adjustable pavameters is made concevning the deviation of the Au-Cu interatonlic distance in long-range ordered (Ll,) Cu-Au I fronl the average distance based on the distances in pure gold and copper. This prediction, which is in agreement with expel-intent, has not been encompassed by any preuious theory. The theory of order-disorder is fragmentary. That is, no one theory exists that can explain the variety of qualitative phenomena observed. Further, many theories are not in good quantitative agreement with experiment. This subject has been reviewed by Muto and Takagi, Tuttman, and Oriani.3 There exists no doubt that the quasi-chemical approximation is not a complete description and that the inclusion of strain energy using macroscopic elasticity theory concepts leads to results in disagreement with experimenL4 The observation of antiphase domains and ordering systems such as Cu-Pt has led to Brillouin zone treat-ment of the order-disorder transition as opposed to the classical Ising model. The objective of this paper is to demonstrate that it is possible to develop a pairwise approximation model that can explain many of the observed order-disorder phenomena that have puzzled investigators in the past. This theory is based upon an empirical model due to ergmman' for the elastic constants of metals. This model is generalized for multicomponent systems. As will be shown, the theory yields a short-range ordering energy for the disordered solution which differs from the ordering energy calculated from the differences in energy of disordered and long-range ordered solutions. It will be demonstrated that there is no necessary correlation between heats of formation and the tendency to order or between size effect and the tendency to order. Also, the existence of antiphase domains and iso-short-range-order systems that form superlattices (Cu-Pt) is predicted on the basis of the theory. Further, the relative stability of competing superlattices is calculable from the theory. If single-crystal elastic-moduli data are available for the pure components and one superlattice then there exists but one adjustable parameter in the calculation of lattice parameters for both the disordered and ordered solid solutions. In one special case, no adjustable parameters are required and a quantitative prediction is made. For the calculation of energies and partial order, there exists but one additional adjustable parameter, the pair-exchange energy V used in the quasi-chemical approximation (or the Ising model.) However, in these calculations, much more precise values are required for the single-crystal elastic moduli than available if the quantitative uncertainties in the predicted values of the energies are to be sufficiently small. THEORY ~er~man' has developed a model with which he was able to obtain fair agreement with experiment for the relations between the elastic constants for metals. This model which we shall call Bergman's model is a linear combination of his models I and 11. In effect, Bergman, in this model, considers that each interatomic distortion is composed of two components: a classical central force distortion with an associated central force constant and what we shall call a linked-central force distortion with an associated linked central-force constant. The linked-central force distortion component obeys the constraint that the sum of such distortions over all the bonds equals zero. No constraint is imposed on the classical central force distortion component. Bergman' derives the constraint on the linked-central force distortion on the basis of application of Pauling's relation between bond distortion and bond number to metals.ga This assumption is not logically necessary, however, and the Bergman model may be taken as a mathematical model for elastic constants, e.g., a purely empirical model without a physical basis. In the present work, the method of Bergman has been applied to two-component systems (solid solutions). In place of an external strain—which would allow a calculation of the elastic constants for the two-component system—it is considered that internal interatomic distortions exist as a consequence of having three potentially unequal distortion-free interatomic distances and but one "average" interatomic distance. It is assumed that the distortion-free interatomic distances between atoms of the same element are those found in the pure element having the same undistorted crystal structure as the solid solution. The distortion-free interatomic distance between unlike atoms is in general not measurable except in the probably nonexistent

Jan 1, 1967

By J. C. Melrose

The contact angle is one of the boundary conditions for the differential equation specilying the configuration of fluid-fluid interfaces. Hence, applying knowledge concerning the wettability of a solid surface to problems of fluid distribution in porous solids, it is important to consider the complexity of the geometrical shapes of the individual, interconnected pores. As an approach to this problem, the ideal soil model introduced by soil physicists is discussed in detail. This model predicts that the pore structure of typical porous solids will lead to hysteresis effects in capillary pressure, even if a zero value of the contact angle is maintained. The model is generalized to situations in which the contact angle takes on values between zero and 40 degrees. For the imbibition branch of the capillary- pressure function, the model predicts a considerable departme ftom the usually assumed cos 0 relationship. In fact, according to the model, it is possible that a displaced wetting phase will not be able to reimbibe, even when the contact angle does not exhibit hysteresis. INTRODUCTION The subject of capillarity in porous media has long been of interest in many branches of engineering and applied science. The earlier investigators were those concerned with the physics of soils. 1-5 More recently, petroleum engineers and others dealing with the problems of petroleum production from reservoir rock have given much attention to the subject.6-10 Also, important additions to the literature of capillarity have been contributed from the field of chemical engineering.11-12 These attest to the wide range of industrial applications in which capillary phenomena play a role. The present paper is concerned with the role which wettability plays in capillary action in porous media. As is well known, capillary-rise (or capillary pressure) phenomena have frequently been interpreted with the aid of a model employing the concept of a cylindrical capillary tube. This approach has enjoyed a certain degree of success in correlating experimental results.13 The generalization of this model, however, to situations which involve varying wettability, has not been established and, in fact, is likely to be unsuccessful. In this paper another approach to this problem will be discussed. A considerable literature relating to this approach exists in the field of soil science, where it is referred to as the ideal soil model. Certain features of this model have also been discussed by Purcel114 in relation to variable wettability. The application of this model, however, to studying the role of wettability in capillary phenomena has not previously been attempted in detail. In the present paper, additional features of the model are introduced. These features are critical in determining the quantitative behavior of the model. GENERAL FEATURES OF CAPILLARY HYDROSTATICS BASIC PRINCIPLES When the interstices of a typical porous solid are occupied by two or more immiscible fluid phases, the fluids are microscopically commingled. Hence, fluid-fluid interfaces are found within a certain fraction of the pore openings. The fundamental equation of capillarity specifies the configuration of these fluid-fluid interfaces. This is known as the Laplace equation, when derived from mechanics, and as the Gibbs-Kelvin equation when derived thermodynamically.15 Given two fluid phases, a and ß, in hydrostatic equilibrium, the Laplace equation states that the respective fluid pressures in regions close to the interface are related by Here oaß is the surface or interfacial tension and rl and r2 are the principal radii of curvature of the surface or interface. The pressure difference, Pa-Pß, is the capillary pressure, PC. As Buff15 has shown, Eq. 1 states the condition for hydrostatic equilibrium within the two-phase confluent region, which is referred to as the interface. It thus can

Jan 1, 1966

By E. Miller, R. Geffken, K. L. Komarek

The thermodynamzc properties oJ liquid Cd-Sb alloys were investigated using the cell arrangement measurments were obtained every 2°C at a heating and cooling rate of 12°C per hr and at equilibrium every 2O0C frorn 500°C down through the stable liquidus. The S-shaped asCd US composition curve was used in the cotnposition regzon near Cd,Sb, to calculate a tempeerture-dependent inleraction coefficient from quasichemical theory. Rapid changes in a scd were observed at a transition temperature varying from 400" to 465°C depending on con/kosition. It could not be determined if the changes in aScd were discontinuous, but tlze composition dependeke of the magnitude of the change is indicative of a second-order phase transformation in the liquid. The values of the experimental changes in ASCd are in agreement with calculations from the slope of the transition temperature, using the concept that a second-ovdev phase transition occurs in liquid Cd-Sb alloys. II is suggested that the transformalion is associated with the formation of Cd4Sb3 molecules in the liquid. ThE structure of liquid alloys is the subject of many investigations. X-ray, resistivity, and thermody-namic data have been interpreted as indicating varying degrees of short-range order in the liquid in alloy systems forming inter metallic compounds. In general, the melting process is not a transition from an ordered to a completely disordered state, but some degree of order is retained in the liquid. Maximum ordering in the liquid state occurs close to the melting temperature of the compound and the arrangement of atoms becomes more random at higher temperatures. Of special interest in this respect is the Cd-Sb system. It is one of the few metallic systems which form both stable and metastable compounds when liquid alloys are cooled at normal rates. The stable system exhibits an intermetallic compound, CdSb, melting at 459"c.l A second compound, CdrSbs, has also been reported,' melting close to this temperature. The metastable system has one compound, CdsSbz, melting at 420"c.I Resistivity measurements on liquid Cd-Sb alloys close to the liquidus temperatures have been interpreted in terms of a complex ordering behavior which changes rapidly with increasing temperature.3 The resistivity-composition curve is characterized by two maxima corresponding in composition to CdSb and CdsSbz. The resistivity-temperature plots show sharp breaks for alloys in the composition range of 45 to 70 at. pct Cd on cooling through a transition temperature close to the stable liquidus. Fisher and phillips4 investigated the influence of temperature and composition on the viscosity of liquid CdSb alloys. The viscosity of some alloys increases sharply on supercooling below the stable liquidus. A maximum in the viscosity-composition curve occurs at the composition CdSb. The thermodynamic properties of liquid Cd-Sb alloys have been investigated by Seltz and ~e~itt' and Elliott and chipmane by the electromotive-force method and their results are in good agreement. However, these investigations were carried out at temperatures well above the liquidus temperatures of the alloys, and the temperature coefficients of the electromotive force, dE/dT, were obtained from experimental points for each alloy at a few temperatures considerably above the liquidus temperature. Scheil and ~aach' investigated the thermodynamic properties of this system by the dew point method in the temperature range from about 100°C above the stable liquidus down into the supercooled liquid region. They reported several anomalies, i.e., the activity of a melt on heating differed from that on cooling, and the activity increased sharply in the limited temperature interval immediately above the liquidus temperature of the stable alloy, followed by a sudden decrease below the liquidus. Values obtained on heating and cooling were not in agreement. A reinvesti-gation of a few alloys by Scheil and Kalkuhl' by the electromotive-force method failed to confirm these observations. The authors concluded that the anomalies were due to inhomogeneities in the starting alloys and they discarded their previous results. The present investigation was undertaken in order to obtain thermodynamic data close to the liquidus temperature and in the supercooled region where the anomalies were originally reported, employing the electro motive-force method. This method is quite precise and will most easily permit observations of small changes in activity and partial molar entropy with temperature. Measurements were taken every few degrees so that the dE/dT values could be calculated over the entire temperature range and small changes in the thermodynamic properties close to the liquidus temperature could be observed. I) EXPERIMENTAL PROCEDURE Specimens were prepared from 99.999+ pct Cd and Sb (Cominco). Surface oxide was removed by scraping and then melting the metals under vacuum and filtering through Pyrex wool. Appropriate amounts of the metals were weighed on an analytical balance to k0.1 mg, sealed in double Pyrex capsules under vacuum,

Jan 1, 1968

By A. B. Parsons

When the Seeley W. Mudd Memorial Fund was established in. 1929 the donors mentioned certain types of projects to which preference might be given in selecting those to he financed by the income from the Fund. One suggestion. was that the projects "be of particular benefit to young engineers." This modest little book meets this specification most aptly. It seeks to guide the engineer-particularly the young one-with the least loss of time and effort to the most convenient source of authentic information regarding any topic in which he may at the moment be interested. Knowing the best place to find the literature on a subject is almost as valuable-and far more practicable-than maintaining a library of one's own large enough to provide the information.

Jan 1, 1933

By Robert Bell

THE " Tar-Sands." is the name which has been given to the extensive horizontal deposit of fine Cretaceous sand, blackened by tarry petroleum, which forms the banks of the last or lowest 130 miles of the Athabasca river before it terminates in Athabasca lake. The Cretaceous strata, to which these sands belong, extend northwesterly from Dakota all the way to this lake and for 500 miles beyond it. The Athabasca river forms the uppermost section of the Athabasca-Mackenzie, one of the great rivers of the world. It rises on the Pacific side of the Rocky mountains, westward of Edmonton, and flows north of east to a point called Athabasca. Landing, 100 miles north of Edmonton, where it turns northward and runs about 280 miles before it falls into the west end of Athabasca lake. The section of this river-system which discharges the lake just named into Great Slave lake, is called Slave river, and below the latter lake it becomes the Mackenzie river. Along the section of 280 miles of the Athabasca river above mentioned, the Cretaceous strata consist of bluish-gray and drab-gray marls, on top, from Athabasca Landing to Drowned rapid, 110 miles down stream; then heavily bedded gray sandstones, 225 ft. in greatest thickness, underlying these, form the banks for about 40 miles further. The strata appear to be horizontal, but they really clip very slightly to the southward. At Drowned rapid, we see the first of the tar-sands resting on almost horizontal beds of bluish-gray limestone of Devonian age. In some places the limestone is associated with shaly or marly bands. Notwithstanding the great hiatus between the two series, the horizontal tar-sands lie conformably upon the almost level upper beds of the limestone wherever the two formations are seen together, all along the river, throughout a

Mar 1, 1908

By E. A. Holbrook

IT may be taken for granted that a mine official knows his duties, as outlined by the bituminous mining laws of the State, he knows how coal should be mined and transported, and he has judgment on any possibly unsafe condition in his mine. Certainly, if he is weak on any of these points, there are definite ways in which he can acquire the needed knowledge. If with this knowledge the mine official has the necessary practical experience to bring self-confidence, he stands before the world as a man who knows his job. There is, however, another side to his work, one not found in hooks, a side even that may not be learned at the face even though one spends a lifetime there. The actual duties a mine official knows and performs are the tangible and definite things about his work. There are other things which may be termed intangible, because they are hard to pin down and see, and. which appear to be of equal importance in successfully handling a job and which in time determine the very success of the company itself.

Jan 1, 1930

By John M. Lovejoy

FEDERAL regulation of the petroleum resources of the nation has long been an interesting topic for discussion. A plan to accomplish Federal control has now taken definite form. At the request of the President of the United States, a bill to be known as the Petroleum Conservation Act of 1939 has been presented to Congress-H. R. 7372, offered by Representative Wm. P. Cole, Jr., and more usually known as the Cole bill. It is an act ostensibly designed to conserve our petroleum resources, through regulation of production practices. Hearings are being held currently by a subcommittee of the Interstate and Foreign Commerce Committee, in compliance with the request of the President to report the bill early in the next session of Congress.

Jan 1, 1939

By Wilfred P. Sykes

AT intervals in the course of history an event occurs which, though scarcely heeded at the moment, marks in retrospect the beginning of a new era in some one field of human activity. Such a happening is perhaps more readily spotted in the field of technology than in other realms of human endeavor. Here the span of years is relatively short and the records have been kept with some degree of precision. In the current scene of our social and economic drama the art and science of metallurgy is playing a major role. Off stage will be found the metallurgist in one guise or another aiding, he trusts, in the development of processes and products which will contribute to the happiness of his fellow men. The results of his efforts appear in the form of metallic substances known as alloys built up from any two or more of the wide variety of metals which have been extracted from the mineral deposits in the earth's crust. An alloy by virtue of its inherent physical properties may seem ideally suited for human use in a special way but until this material can be produced economically it will fail to attain a place of prominence as an article of commerce. In fact many commercial alloys are being continually replaced by new or modified compositions better suited to meet the increasingly severe demands of industrial service.

Jan 1, 1939

By R. H. Oliver

The purposes, types, preparation, and testing of flocculants are discussed. A flocculation compendium is included, indicating choice of flocculant for a given set of conditions. An economic evaluation of the process is presented. Solid-liquid separation is a major expense in most mineral processing flowsheets today. Proper use of flocculation can often lower the overall cost of a solid-liquid separation by reducing the size of sedimentation or filtration equipment. PURPOSE OF FLOCCULATION When is use of a flocculant justified in terms of overall process economy? 1) when it results in process improvement, such as producing a clear liquor for electrolysis, precipitation, ion exchange, or solvent extraction; 2) when it results in satisfying requirements of pollution abatement ordinances; 3) when it results in increased recovery of values that would otherwise be lost; or 4) when it results in considerable savings in capital expenditure due to use of smaller equipment. When can the use of a flocculant adversely effect overall process economy? 1) when it results in increased filter cake moisture, 2) when it results in decreased filtration rates, 3) when it results in considerable bulking of sedimentation underflow, 4) when it contaminates either the supernatant or sludge, or 5) when the cost of using the flocculant is greater than the savings due to its use. First step in consideration of flocculants for a given application is establishment of desired goals in terms of increased clarity of effluent, increased recovery of solids, or decreased size of equipment. The most economical solution to a solid-liquid separation problem is that combination of equipment and flocculant costs which meets the established goals at the lowest total annual expenditure. This economic decision can be made only after technical data has been obtained as outlined in next four sections. TYPES OF FLOCCULATION Flocculation is a process wherein individual particles are united into more or less tightly bound agglomerates or flocs, thereby increasing effective particle size of solids suspended in a liquid. Degree of flocculation of a suspension of finely divided solids in a liquid is controlled by a combination of probability of collision between particles and probability of adhesion after the collision has occurred.' Probability of collision can be increased commercially through use of a paddle-type flocculator, combination flocculator, and clarifier or flocculating-type feedwell. Probability of adhesion usually can be increased by addition of a reagent known as a flocculant. Reagents act as flocculants through one or a combination of three possible mechanisms. The first is electrolytic neutralization of inter molecular repulsive force due to Zeta potential. This neutralization enables Van der Waal's cohesive force to hold the particles together after they collide.' The second is the precipitation, within a definite pH range, of voluminous metallic hydroxide flocs which entrap fine particles. This process is known as coagulation.14 Third is the bridging of two or more particles by either natural or synthetic long-chain, high-molecular-weight organic polymers. This bridging is accomplished by adsorption of two particles at different sites on the same molecule or by bonding of two molecules, each adsorbed to a different particle. Considerable effort has been expended in explaining the action of these polyelec-trolytes and detailed accounts are available in the literature. CHOICE OF FLOCCULANTS It is impossible, at the present time, to specify the optimum type or amount of flocculant for a given application from a knowledge of the material to be treated. The standard procedure is to choose reagents or combination of reagents most likely to be effective on the slurry; then test them.' The accompanying Flocculation Compendium (Table I) contains details of all currently available reagents sold as flocculants and it should be used when selecting the group of reagents for tests. This selection can be based on information listed in columns 4 and 5. Column 4 presents industries in which each floc-

Jan 1, 1961

By P. D. Merica

ALUMINUM and its alloys have been the subject of much investigation, during recent years, in the course of which the principal features of the constitution of most of the binary alloy systems with aluminum have been determined. Except in the case of a few metals-silicon, bismuth, cadmium, lead, zinc, and tin-an aluminum-rich compound is formed in each binary system, which forms a eutectic with the aluminum or its solid solution with this compound. Thus such compounds as FeAl3, CuAl2, Mg4Al3, and NiAl3 are formed, which are found in aluminum-rich alloys of their respective series as eutectics with the aluminum solid solution. These compounds are, in all cases, hard and brittle and their presence affects profoundly the physical properties of the alloys in which they occur. Within the zinc-aluminum system a compound, Al2Zn3, is formed that decomposes at lower temperatures. Silicon and tin each form a simple eutectiferous series with aluminum; bismuth, lead, and cadmium are only partly miscible in the liquid state with it. The extent of the solubility in aluminum, in solid solution, of these compounds or of the elements themselves, in the case of those series

Jan 7, 1919

THOSE MARKED THUS * ARE MEMBERS, MARKED THUS t ARE ASSOCIATES THESE SIGNS DOUBLED INDICATE LIFE MEMBERS AND ASSOCIATES RESPECTIVELY THE FIGURES AT THE END OF THE ADDRESS INDICATE THE YEAR OF ELECTION HEAVY FACED TYPE SIGNIFIES HONORARY MEMBERSHIP ` *AARONS, JULIAN B , Mine Supt, The Boulder Deep Levels, Ltd , Boulder, Western Australia, '05 *ABADIE, EMILE R, Cons and Min Engr, 1004 James Flood Bldg, San Francisco, Cal '76 *ABBE, CLEVELAND, JR, GeOl Aid, U S Geological Survey, Washington, D C '00 *ABBOTT, AI ARTHUR, Cerro de Pasco Mining CO , Cerro de Pasco, Peru, So America '95 *ABBOTT, ARTHUR V , Electrical Engr , Westinghouse, Church, Kerr & CO , 8 Bridge St, New York, N Y '82 *ABBOTT, CLARENCE E, Chief Min Engr, Care Fayal Mine, Eveleth, Minn '04

Jan 1, 1910