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By W. F. Holbrook, C. E. Wood, E. P. Barrett

The high-frequency laboratory induction furnace with a rotating liquid crucible enables research workers to conduct certain investigations heretofore very difficult or impossible to realize because vessels are not obtainable that are capable of resisting the physical conditions or the chemical actions to which they are subjected. Applications for patents covering commercial uses of centrifugal liquid crucibles were filed in the United States in 1919,' in France in 1925, in the United States and Germany in 1926,2 and in France in 1927.3 In 1928, Schuette and Maier,4 of the Bureau of Mines, reported the construction of a whirling table beneath a high-frequency induction furnace. Shape and Size of Centrifugal Liquid Crucibles When a vessel containing a liquid is rotated, the inner surface of the liquid takes the shape of a paraboloid under the simultaneous action of centrifugal force and gravity. The internal dimensions of the paraboloid rotating liquid crucible are governed by the diameter of the container and its speed of rotation. Melted Wood's metal was poured into cylinders 2 1/2 in. in diameter, which were rotated at 180, 300, and 468 r.p.m. When the metal was solid, a slurry of plaster of Paris was added, and rotation continued until the plaster had set. Fig. 1, a photograph of sections of the cylinders, shows the effect of speed of rotation of the containers upon the shape of the inner surface of the rotating liquid crucibles. Types of Furnaces Three types of high-frequency induction laboratory furnaces using liquid-metal crucibles were designed and constructed by the Blast

Jan 1, 1939

By American Institute of Mining Engineers

David J. Mack (University of Wisconsin, Madison, Wise.)—Have the authors considered that the effects reported in their paper are readily explainable on the basis of equilibrium grain boundary segregation rather than ordering? It seems to the writer that all of their experiments and observations correlate well with known behavior associated with equilibrium grain boundary segregation. Although at first glance one would tend to dismiss such a possibility because of the similarity of the gold and copper atoms, their sizes differ by 12.8 pct which is in the range where segregation at grain boundaries would be expected. Then, too, the electrochemical differences between the copper, the Cu3Au, and the gold strongly suggest that a segregation mechanism is involved in the corrosion of the Cu-Au alloys. R. Bakish and W. D. Robertson (authors' reply)—The authors would like to thank Dr. Mack for his consideration of the problem of grain boundary segregation as an explanation of the observed phenomena. We had considered the problem in the following terms: Assuming a pure binary Cu-Au alloy and an ideal solid solution, the surface excess, T2= N25 — N2, of the second component (gold) may be expressed in the following way20 1 —exp (—da/kT) where 8 is the difference in surface tension of copper and gold, and a is the surface area per atom. In the present case, 6 is positive which implies that the component in excess at the boundary is gold. Since the only chemically active component in ferric chloride is copper, it does not appear that the segregation of gold is likely to increase the boundary activity. A small concentration of a third component could profoundly affect the situation. Analysis indicated only spectrographic traces of impurities, all of which are soluble in both copper and gold. Quenching experiments, reported in the paper, also tended to eliminate significant effects attributable to a third component.

Jan 1, 1958

By Alexander L. Field

The rate of elimination of carbon largely controls the time required to make a heat of steel by the basic open-hearth process and to an important degree determines the cost of refining. Practical experience has led to the generally accepted belief that the use of slags relatively high in iron oxide, such as are required to bring about rapid refining, leads to a certain sacrifice of quality in the product. As a consequence, a compromise must be made between the exceedingly slow rate of carbon drop which would correspond to the ideal case and the rapid rate which would best satisfy the condition of minimum cost. An increase in rate of refining necessarily implies an increase in the concentration of iron oxide dissolved in the metal. However, even for the infinitely slow rate that corresponds to slag-metal equilibrium, the metal would contain a certain definite concentration of dissolved iron oxide. It is a matter of great practical importance, therefore, to determine the quantitative relation between the minimum or equilibrium concentration of iron oxide in the metal and the higher concentrations which must actually obtain in practice. The present paper is devoted to the development of certain equations, derived from the established laws of physical chemistry, which will enable this relation between rate of refining and the degree of oxidation of the metal bath to be computed from operating data. So attempt is made to exhaust the possibilities of this general method of treatment. In considering rate of refining, attention is mainly confined to rate of carbon elimination. However, the equations are of a more general nature and their application may readily be extended. The results of the preliminary calculations given herein indicate that increased rate of refining may have a decided effect in increasing the concentration of iron oxide dissolved in the metal. The uncertainty which attaches to the calculated value for this relationship arises in part from probable errors in experimental data on which the calculations are based, and in part from the lack of complete or favorably disposed information on basic open-hearth practice. When the relation between rate of refining and degree of oxidation of the metal has been more accurately established than has been done in the present paper, it will then become possible to consider what comprises

By Richard P. Schoemaker

Introduction In underground mining operations the effects of economic and mechanical factors on costs and profits can readily be appreciated and can perhaps be expressed in exact figures and percentages. Less apparent, but frequently more important, is the influence of physical stress. Stress causes failure of supports, collapse of openings, rockbursts, and other damage which directly affects the costs of maintenance, and also to a certain extent the accident rate. Stress can, however, if properly directed, be an aid to mining operations. The caving methods in metal mining and the long-wall method in coal mining are well-known examples. In large-scale mining operations it is almost impossible to neglect stress-control. A better understanding of the mechanism of rock pressure and the application of its principles to practical mining will inevitably lead to a reduction in operating costs. Many theories have been advanced to give the mining engineer a practical outline for stress-control but, although today most experts agree upon the principles of stress distribution around underground openings, there is still no generally accepted theory that explains all phenomena. The main reasons for this incomplete understanding of the problem are the lack of accurate knowledge of the physical properties of rocks under field conditions, and the great complexity of these conditions due to in-homogeneity of the rock, stratification, tectonic disturbances, and many other unknown factors. The research on the rock pressure problems has, however, yielded some valuable facts which, expressed in practical terms, and adapted to local conditions, may become a valuable aid for mining operations. The purpose of this paper is to give a review of the most important accomplishments of this research with respect to the stress phenomena around small underground openings, such as tunnels and shafts, so as to arrive at an outline of the problem as it stands today. Special emphasis is placed on a new theory by the German mining engineer, Rudolf Fenner, which has never before been published or discussed in English. The Pressure Dome Theory The formation of a dome-shaped space around underground openings is well known from field observations. When openings are made in rock under stress, the rock in the top of the openings will often fail, and caving will continue until the openings have assumed a dome-shaped form, after which equilibrium apparently is re-established. The oldest theory which attempted to explain the phenomenon is the "beam" theory, which postulates that the hanging wall consists of stratified measures that behave as independent beams with fixed ends and a uniformly distributed load. When failure of the beam occurs, inward shearing at the ends will cause the formation of a dome-shaped space. The pressure dome theory, which more or less evolved from the beam theory, merely

Jan 1, 1949

By Persifor Frazer

TILE ore property of Mr. Augustus Roop is situated about one and a half miles south of the New Windsor Station of the Western Maryland Railroad and is connected with the town of New Windsor by the Liberty and New Windsor Turnpike. It is about forty miles distant from Baltimore, and about seven miles west from the county town of Westminster, and a little more northeast from the celebrated Liberty Copper Mines. (See accompanying Maps 1 and 2.) The property comprises about 140 acres, lying principally

Jan 1, 1881

By Earl H. Miller, Henry H. Bruhn

COMMERCIAL beds of sylvite ore were discovered by the Snowden & McSweeney Co. while drilling a wildcat oil well some 25 miles northeast of Carlsbad, N. NI., in 1925. After a preliminary core drilling program the U. S. Potash Co. sank a 1060-ft shaft within 4 miles of the original discovery. This shaft was in an isolated location in a sand desert area with only the roughest of dirt roads connecting it with the neigh- boring town of Carlsbad some 21 ½ miles west.

Jan 6, 1954

By Ernest Kirkendall

THE amount of research done in the last few years on the subject of diffusion in solid metals is significant of the importance of this problem. To review the literature dealing with diffusion is unnecessary here. Desch1 in 1912 reviewed the work that had been done on diffusion in solids and gave a bibliography of the literature published before that time. Mehl's paper in 1936 2 is an excellent review of diffusion in metals and contains a large bibliography. Of importance also for its review and bibliography is an article by A. I. Krynitsky.3 While considerable material has appeared in the literature on diffusion in brass, the amount of information is not great compared to that pertain-ing to some of the other alloys. Most of the information published is of a qualitative nature; that which is quantitative varies considerably. Thus the quantitative determination of the rates of diffusion of copper and zinc in alpha brass by a new method appeared worth while. In the present investigation the rate of diffusion of zinc in approxi-mately the same composition alpha brass has been determined at three temperatures.

Jan 1, 1938

By Teder R. I., M. M. Protodyakonov

In order to find an empirical relation between a quantity F and (m) independent variables or factors, each of which take (n) different values or levels, it is necessary to conduct nm different experiments (all possible combinations of the factors), each of which has to be repeated a few times (usually five) due to the scattering of the data. The total number of such experiments is very large, thus for example, when m = 4 and n = 5, it is equal to 5.54 = 3125; and very rarely is it possible to conduct such a number of experiments. Various possible methods of planning partial experiments are illustrated in Fig. 1. Each method shows a large combinative square consisting of five columns and five rows of middle squares, each of which, in turn, is further divided into five columns and five rows of cells. Such a partition corresponds to a plan of an experiment with four factors, each of which takes five different levels. The blackened cells indicate the combination of factors in a partial experiment. The total number of experiments is reduced on the basis of the following considerations: a) The effect of only a few levels of some factors is studied (Fig. la). Such an investigation gives no information on the effect of some factors, therefore it cannot be accepted as satisfactory; b) By reducing the number of levels of each factor; in such a case it is not possible to obtain an empirical relationship, but only whether some factors have an effect. This is evidently inadequate;

Jan 1, 1971

By N. J. Olson, G. W. Toop

A series of equations previously derived for calculating ternary thermodynamic properties using binary data has been applied to the problem of predicting ternary phase diagrams and quaternary excess free energy. The methods are considered to be rigorous for regular ternary and quaternary systerns and empirical for nonregular systems. The equations have been used to predict ternary phase boundaries in the Pb-Sn-Zn system at 926°K and the Ag-Pd-Cu system at 1000ºK. Calculated quaternary excess free-energy values are presented for the Pb-Sn-Cd-Bi system at 773°K. A method for predicting the location of ternary phase boundaries would be a useful supplement to experimental measurements in ternary systems. This has been recognized with the considerable work that has been done to find models to predict or extend thermodynamic properties and phase diagrams in binary and ternary systems1-18 for which direct experimental measurements are limited. With the access to highspeed digital computers and mechanical plotting devices, it is currently rather easy to compare mathematical models with experimental data. The regular-solution model is consistent with systems which exhibit negative heats of mixing, positive heats of mixing, and miscibility gaps, and therefore it is applicable to simple phase diagrams. The purpose of this paper is to illustrate the use of regular-solution equations to predict, empirically, phase equilibria in some types of nonregular ternary systems. Corresponding equations for regular quaternary systems are given and used to calculate empirical quaternary excess free-energy data. METHOD FOR PREDICTING THE LOCATION OF TERNARY PHASE BOUNDARIES USING BINARY DATA Meijerin1,6 has used the regular-solution model to calculate common tangent points to ternary free energy of mixing surfaces and hence to determine phase boundaries in ternary systems involving miscibility gaps. He used the following equation to calculate ternary excess free energy of mixing values: stants characteristic of the binary solutions, and Ni is the mole fraction of component i. An alternate expression which gives for regular solutions as a function of binary values of along composition paths with constant N1/N2, N2lN3, and N1/N3 may also be derived:15 ternary r xs 1 ?c-*n.Ti*.U*. This expression for is more useful for the empirical calculation of ternary excess free-energy values for nonregular systems because actual binary AFXS data may be used in the expression rather than attempting to find suitable constants for Eq. [I]. The results of this feature of Eq. [2] are illustrated in Table I where calculated excess free-energy values for the Ni-Mn-Fe system at 1232°K are compared with experimental data of Smith, Paxton, and McCabe.19 Although regular-solution equations have been shown to give calculated thermodynamic quantities which agree quite well with experiment for single-phase nonregular ternary systems,14,15 care should be exercised in the use of the equations to predict thermo-dynamic properties of multiphase ternary systems in which strong compound formation is suspected. This precaution is consistent with the simple regular-solution model which for negative values of ai_j will indicate a tendency toward compound formation but even for very large negative values of ai-jwill not give multiphase binary or ternary systems involving a distinct stable compound. Hence, calculated ternary free-energy data using Eq. [2] might be expected to vary between being rigorous and poor, in the following order, for ternary systems which are: a) regular solutions, b) nonregular single-phase liquids in which random mixing is nearly realized, c) nonregular single-phase solids, d) nonregular multiphase systems exhibiting miscibility gaps, e) nonregular multiphase systems with binary compounds but no ternary compounds, f) nonregular multiphase systems with highly stable binary and ternary compounds. The calculated data will be expected to be least accurate for the last two cases. The general method adopted in this paper involves two-dimensional plots of ternary activity curves. The principle used is that tie lines indicating two-phase equilibria join conjugate phases a and B for example, for which a1(a) = a1(B), a2(a) = a2(B), and a3(a) = a3(B). Tie lines may be determined by plotting the ternary activities of two components along an isoactivity line for the third component and the unique points where the above equalities hold may be found graphically.

Jan 1, 1970

By Kenneth A. Moon

An exact statistical treatment of a one-dimensional model is used as a basis for evoluating the reliability of certain simplified expressions for the activity of the solute in interstitial solutions, including one obtained from the exact expression by setting the repulsive interaction equal to infinity. The latter approximation is found to be satisfactory at low and moderate concentration if the repulsive interaction is large, even though not infinite. A similar expression (identical if the co-odination number is two) is derived from the quasichemical expression of Lacher, and is recommended as the best available expression for the excess configurational entropy of interstitial solutions with excluded sites. Some reasonable models are discussed, and the nature of the saturated solutions is determined by inspection. Some of the models reduce to the one -dimensional case. An analysis is given of the excess partial entropy of hydrogen in V-H; Nb-H; and To-H solutions. MOST treatments of the statistical thermodynamics of interstitial solid solutions have followed the classic paper1 of Lacher in making the simplifying assumption that the configurational entropy of the solution is ideal. However, it is becoming increasingly apparent that there are many interstitial solutions with very large so lute-solute repulsions, and for these the assumption of ideal entropy is not valid or useful. It is important to realize that with substitutional solutions large repulsions between the component atoms must lead to phase separation, whereas in interstitial solutions the free energy of the solution is not drastically increased by large solute-solute repulsions until intrinsic saturation is reached at the concentration where further solute would be forced to enter a site in which it would experience the repulsive effect of one or more solute atoms already present. In the limiting case of an infinitely large repulsive interaction, the excess free energy would be attributable entirely to excess entropy, the enthalpy of mixing being zero. AS will be shown below, even if the repulsions are less than infinite, a treatment based on an assumption of infinite repulsions may be very satisfactory up to moderately high concentrations of the interstitial component. Often in solutions where large repulsive interactions exist, there are also small interactions — often attractive—between solute atoms in configurations other than that corresponding to the large repulsion. In such cases the excess free energy will consist of an excess entropy term attributable to the large repulsive interactions, and an enthalpy term corresponding to the other small interactions. Nomenclature to differentiate succinctly between important cases would be a convenience. In this paper the nomenclature shown in Table I will be used. In Table I, and in the preceeding discussion, excess quantities are defined in terms of standard states which are pure solid solvent and pure (possibly hypothetical) solid saturated phase of the structure in question. In practice, it is more convenient to choose the interstitial element as a component, and its conventional standard state. This will add a composition-independent term to the excess entropy and the enthalpy. The earliest paper known to the present author which treats the thermodynamics of athermal interstitial solutions was given by schei12 in 1951, but the statistical derivations in that paper are open to criticism. Speiser and Spretnak were the first to give a correct statistical treatment,3 limited, however, to concentrations sufficiently low that the number of empty sites excluded from occupancy by more than one filled site is negligible. The purpose of the present paper is to extend the statistical treatment to more concentrated solutions, and to examine the magnitude of the errors introduced by assuming that the repulsive interactions are infinite when in fact they must be finite. THE QUASICHEMICAL APPROXIMATION Fortunately, a standard method already exists for taking into account the effect of large interactions upon the entropy of mixing. This is the quasi-chemical method, in which the probability of existence of a given pair of solute atoms in a certain proximate configuration is assumed to be proportional to exp(-w/kT), where w is the energy increase of the solution when the two atoms are moved from isolated locations in the solution to the configuration in question. A quasichemical treatment of interstitial solutions was given in 1937 in a widely neglected paper by Lacher.4 The result comes out

Jan 1, 1963

By H. Rumfelt

The author demonstrates an approach for analyzing overcasting requirements for a stripping project. This approach to the problem employs indicated trends in the relationship of the weight of the machine (only electropowered draglines are considered) to its ability to do stripping work. Strip mining in the domestic coal industry is contributing a greater proportion of overall production than at any time in the past. U.S. Bureau of Mines statistics show that the percentage of total production mined in 1958 by stripping methods increased to more than 30 pct, up from 22 pct in 1951. The tendency to favor strip and open pit mining exists in other mining activities, but such trends are not as clearly outlined as in the coal industry. Significantly, the depth of overburden in coal properties considered suitable for stripping is also increasing. A depth of 50 to 60 ft of overburden was once considered to be about the maximum amount that could be handled economically. Today, a depth of 80 to 100 ft is frequently taken into consideration for simple overcasting operations (i.e., excavating overburden and dumping it in the spoil position where it remains indefinitely). Accompanying these changes, there have been continuing studies searching for procedures to appraise deeper stripping problems. Although the only known practicable way to accurately evaluate a proposed stripping venture is to make studies (including cost estimates) step by step, it is nevertheless desirable to have a quick method for making preliminary evaluations of potential strip mining operations. A recently devised digital computer method of providing a preliminary simple overcasting analysis for a stripping prospect relates the indicated trends in the relationship of the weight of the machine to its ability to do stripping work. In addition, this approach employs situations where the geometry of each cut-and-spoil section is assumed to take certain defined relationships for varying overburden depths. Slopes are necessarily considered to be stable, which means such practical factors as the mechanics of soils are neglected for the sake of convenience. Definition of Terms: Photographs A and B show a shovel-type and a dragline-type of simple overcast operation, plus terms used to denote certain parts of a pit. Pits that follow a straight line when projected on a horizontal plane are referred to as straightaway. It has been assumed that all section drawings accompanying this article pertain to straightaway cuts which, in turn, means that areas can be compared by relative volume. The volume of overburden is measured in virgin cubic yards. Material displaced from its virgin state to a spoil area normally occupies a larger volume than when in situ; the difference is termed swell, and it is expressed as a percentage of the original volume. For example, if the original cut volume is denoted V cu yd, and the spoil volume is 1.2 V cu yd, the swell is a positive 20 pct. MAXIMUM USEFULNESS FACTOR (MUF) CONCEPT Men experienced in overburden removal give emphasis to the weight of the machine in relation to its value as an excavator. From the writer's understanding, value has been only loosely defined and discussed generally and vaguely. The concept is considered important, however, since it is based upon the observations of many men. It provides a clue for the approach taken to solve deep stripping problems. In the procedure described below, value has been arbitrarily established as the product of the nominal dipper size of the shovel (or dragline) times a functional dumping reach. MUFs—Shovel: A shovel's capability to handle thick overburden is usually limited by its ability to dispose of the spoil. Thus the dumping reach, as well as its dumping height, is significant. The angle of repose of spoil material must also be considered. Although such slope angles vary among different mines, jobs, and materials, a slope of 1.25 to 1, frequently found in both planning and practice, is used by this author in the illustration of this analytical method. The relationship of the shovel's geometry to a stripping operation is shown in Fig. 1. To gain maximum advantage in constructing spoil piles, the shovel is placed so that its tracks adjacent to the spoil are as close as possible to the rib of the coal deposit. A vertical plane passing through the line

Jan 1, 1961

By A. Beeby Thompson

FOR more than 2500 years, natural gas issues in the Surakhany district of the Apsheron peninsula were the object of pilgrimages by fire worshippers and Hindoos from Burma and India. Even as late as 1890, Hindoo priests conducted ceremonies in a temple at Surakhany, which probably replaced a more ancient one; but later, the visits of the pilgrims were prohibited in order to check the spread of Asiatic diseases in that region. For centuries, limited supplies of oil have been abstracted from shallow excavations in the Caspian oil belt and dispatched into the interior of Asia and elsewhere for medicinal and industrial purposes. Statistics show a yield of 37,400 bbl. in 1863, but only since 1869 has there been serious development; in that year the yield was 203,000 bbl. At that time, hand digging was supplanted by drilling, and the enormous wells that resulted from tapping sources hitherto beyond the reach of operators completely demoralized the industry for a time, owing to inadequate outlets for the products. The early activities in this area were greatly hindered by annoying taxation, monopolies, imperial land grants, etc., but when these were revoked or adjusted, in 1877, the industry sprang into prominence and, between 1898 and 1901, the Baku fields produced practically one-half of the world's supply of oil. Within a few miles of Baku lie the two richest oil fields in the world; viz., the Balakhany-Saboontchy-Romany and the Bibi-Eibat, the latter constituting almost a suburb of the city. For many years the gasoline obtained in the refineries of the Baku area was burned in pits, being considered an undesirable product, and until 1870 the residue also was destroyed, its value as a fuel not being recognized. Kerosene was the main product sought by the refiners. It was shipped across the Caspian Sea and up the Volga to the industrial centers of Russia. Only on the completion of the Baku-Batoum railway did the Baku oil fields secure

Jan 8, 1920

By T. T. Read

A SHORT time ago, one of the large steel companies courteously furnished the author with detailed records of the operations of a considerable number of iron blast furnaces over a period of two months. These will be made the basis of a subsequent study, but in beginning this study one of -the first points requiring consideration was the probable error of the records, for what otherwise might be regarded as significant differences of performance under different conditions were perhaps really due to errors of observation, or failure to observe and record variations. If it is assumed, in blast-furnace records and calculations, that known quantities or factors are constant, when as a matter of fact they are variable, the effects of these variations may erroneously be ascribed to some other cause. This is quite clearly expressed in the following quotation from E. Buckingham:1 Theory always operates on an ideally simplified picture of reality because real phenomena are unmanageably complicated. The results obtained are not exactly true for any, real phenomenon, though they may be for an ideal one; and the approxi¬mation with which a theoretical equation, however obtained, represents the actual facts, always depends on the approximation in essentials between the ideal picture and its real prototype. The purpose of dimensional reasoning is to find out how some quantity which is involved in the phenomenon under consideration is related to certain others; or to find the relation connecting two or more quantities which vary, or may vary, simulta-neously during the course of the phenomenon. Since we know that we must have a complete equation to start with, we begin by thinking the matter over, to see whether the quantities we have in mind are the only ones involved. Usually it is evident that they are not; so we next make a list of all the quantities we can think of which might under any circumstances be important. Upon considering this list, which is often a long one, it is usually evident that under the actual circumstances a number of these quantities may safely be ignored; so we cross them off the list and thus pass from our most general conception of the phenomenon to an ideal simpler one, in which these quantities are not involved at all.

Jan 3, 1925

By N. V. Hansell

The last few years have shown an increasing interest in the subject of beneficiating iron-ores in all iron-producing countries. In the United States, this movement has been slower than in certain parts of Europe, for the obvious reason that the abundance and relative cheapness of the Lake Superior irou-ores has hindered the development of enterprises for the preparation of low-grade ores. Gradually, however, conditions have changed. The world's consumption of iron is increasing enormously. Being in 1900 about 40,000,000 tons, in 1910 it was already 60,000,000; and there is no reason to doubt that for the near future the increase in iron-cousumption mill continue at the same rapid rate, especially with the development of China, certain parts of Africa, and other regions which have hardly been touched as yet by modern industrialism. It is, therefore, not surprising that apprehension is felt that the known available iron-ore resources of the world are gradually being depleted. Signs of this feeling are the recent iuvestigation, under the direction of the U. S. Geological Survey, of the iron-ore resources of the United States, and the estimate presented to the last International Geological Congress, at Stockholm, Sweden, of the iron-ore resources of the world. These investigations have emphasized the fact that the known high-grade ore-deposits are limited in extent, and will, at a not distant future, be exhausted, compelling the iron industry to depend for raw material on the enormous deposits of low-gratle ores which are distributed over almost all the world. The discovery of new deposits of high-grade ore, in countries not yet thoroughly explored, will not materially change this prospect. Of course, the part which such new deposits will play in the future cannot be forecast. The difficulty and cost of transportation will probably exclude many of them from use at the present centers of the iron industry.

Jan 1, 1913

By R. L. Wiegel

The two questions considered in this study are: (1) what similarity is there in the liberation of magnetite from various iron formations, and (2) how is this liberation affected by the size reduction technique employed. Twelve sample suites were obtained from commercial concentrators processing magnetite iron formation in the United States, Canada, and Australia. These samples have grades in the range 15 to 45% magnetite iron and approximate mineral grain sizes o f 50 to 2000 microns. Efforts were directed at measuring the liberation characteristics of the samples obtained from the concentrators primary grinding mills. The Davis tube, a laboratory magnetic separator, was used to concentrate individual size fractions of the size reduction product to determine liberation data. These liberation data were compared with relationships calculated from a highly idealized mathematical model of liberation in a binary mineral system. The results of these comparisons have been encouraging for nine or ten of the twelve samples tested. This leads to the conclusion that for most commercial iron formations, at least with conventional rod mill size reduction, it is possible to quantitatively characterize liberation with two parameters: an effective mineral grain size and ore grade. Limited laboratory size reduction tests as well as one of two sets of liberation data from commercial primary autogenous grinding lend some support to the contention that autogenous grinding can affect mineral liberation.

Jan 1, 1976

By J. G. Thompson

OXYGEN, nitrogen and hydrogen are present in practically all metals in one or more of the following forms: (1) molecular gas in blowholes or blisters, (2) combined in nonmetallic inclusions such as nitrides, oxides or silicates, and (3) in solid solution in the metal. Gaseous elements, in some of these forms, are encountered in practically all metals and alloys but possibly have received most publicity in connection with iron and steel. In fact, the entire steel industry depends upon the control of the oxygen content during the refining process, as well as in the finished material, and it was only after the adoption of the use of efficient deoxidizers such as manganese that the production of good steel with a low carbon content became possible. In normally clean, sound steel the amount of hydrogen is negligible and the amounts of oxygen and nitrogen vary from a few thousandths to a few hundredths per cent. However, many of the effects attributed(27,31,40.41,53,54,55,56,62) ? to the presence of these elements are important and at first glance appear to be out of proportion to the amounts of impurities involved. The presence of oxygen is believed to affect the solubility of carbon in austenite and ferrite and thereby to affect the structure of the iron or steel. Such properties as strength, hardness, ductility, elastic limit, impact resistance, magnetic permeability, tendency toward caustic embrittlement, irregularity in carburization, the cutting life of tools, certain corrosion phenomena, the presence of flakes, seams, bands, ghost lines and hair cracks, and the tendency to age-harden, all have been attributed to the presence of oxygen.

Jan 1, 1932

By H. W. Miller, V. H. Wilhem

Although the year 1933 was a period of uncertainty, considerable new development was initiated, with a high percentage of favorable results, for owing to financial conditions only projects of merit were proposed and developed. Unfavorable marketing conditions caused severe financial losses to refinery and sales departments of nearly all companies during the first half of the year. In anticipation of stabilized Government control, earnings were generally favorable during the third quarter but failure of the Government to take legal action against violators of the proration orders, and lack of agreement on a definite plan of curtailment, resulted in considerable overproduction and demoralization of the market structure during most of the final quarter. However, toward the close of the year Government action against violators of the Oil Code had a tendency to decrease overproduction materially and give the market a firmer tone. As a whole, the price structure of crude oil was maintained at a high level during the year; in fact, at a much higher level than the price of refinery products warranted. At no time during the year was production within 10,000 bbl. daily of the state allotment, overproduction of crude reaching a peak of 70,000 bbl. on Sept. 7, average daily average for the year being about 27,000 barrels. Numerous plans for equitable curtailment were prepared and tested during the year, none of which fully solved the many and intricate problems faced by operators who were in most cases willing to curtail if they could feel that cooperation was being practiced by their neighbors. Outstanding events in California oildom during the period under discussion may be classified under the following headings: 1. New discoveries. (a) New development in proven areas. (b) Deeper zones in settled pools. 2. Unproductive wildcat operations. 3. Whipstocking practice and procedure. 4. Progress of unit and orderly plans of development.

Jan 1, 1934

By R. A. Vandermeer, C. J. McHargue

The (001) fiber-texture component, found in aluminum rods extruded at subzero temperatures, consists of particles of various sizes having extremely irregular shapes dispersed in a nonuniform way throughout a matrix of the (111) orientation. Apparently the (001) texture component is not a result of recrystallization but rather is due to the presence of reimanents of the original grains which fragmented from the main body of material as it reoriented towards the (111) orientation during the extrusion process. Both X-ray line-broadening measurements and electron-microscopic observatwns indicate that, after extrusion, regions having (001) orientations are in a state of relatively less strain and distortion than (111) regions, suggesting that the former have undergone less plastic deformation. A (001) fiber-texture component is also found after complete recrystallization of extruded specimens. Approximately one third of the recrys-stallized volume has this orientation. The (001) fragments, formed during the extrusion process, act as nuclei for recrystallization; i.e., the pain boundaries separating these fragments from the matrix are capable of migrating during annealing. Electron-transmission microscopic observations and X-ray line-broadening measurements indicate that (001) regions recover at a much more rapid rate than (111) regions at annealing temperatures up to 187°C. DURING the extrusion of a rod or the drawing of a wire the individual grains comprising the piece tend to reorient towards a preferred orientation (texture) which is of the fiber type where a particular crys-tallographic direction, (uvw), in each crystallite tends to be aligned parallel to the longitudinal axis

Jan 1, 1964

By H. A. Guess

INTRODUCTION. HISTORY AND PRODUCTION STATEMENTS. SOUTHEAST Missouri is the oldest of the large producing districts of the United States. The first recorded production from disseminated ores was in 1869, although for many years prior to that time lead had been mined from shallow pockets, and steady growth in production has been shown ever since, the greatest increases being during the past five years. The production by years for each of the operating companies from 1869 to 1907, inclusive, is given in Table I. In Table II. is given the production by years from 1908 to 1912, inclusive, for the district as a whole, showing the tonnage of crude ore mined, yield in concentrates, average assay of concentrates; yield in metallic lead both per ton of crude ore and in total; also approximate value of the yearly production.

Jan 12, 1913

By George Stanley Scott

Many requests for information as to the possibility of washing coals to some predetermined percentage of ash or sulfur have suggested that the producers aim to satisfy some degree of purity set by the user of the fuel, rather than to attain the greatest economic benefit to all concerned. This paper is written to show that the highest economic purity of washed coal can be determined from washability studies of the raw coal, costs of mining and washing coal, and data on the effect of ash and sulfur on the value of the coal for the particular use for which it is intended. Coke fob Blast-fuenace Use For purposes of illustration, we take the case of coal washed for coke to be used in the iron blast furnace. The method outlined can be made general in its application by substituting for the figures used here the actual operating figures for the particular case under consideration. In general, it costs the blast-furnace operation from 8 to 25 c. per ton of pig iron to slag out each 1 per cent. of ash introduced into the blast furnace by the coke. This figure depends on which one per cent. of ash is removed, and decreases with decrease in ash. When blast furnaces and coal mines are considered as a whole, the figure decreases to zero and then becomes negative, on account of low recovery of washed coal. Various figures1 have been given by different investigators. These figures necessarily differ, not only on account of the differences in operating costs but on account of the difference in the respective fuels as well. For the purpose of this paper, which, as explained, is to point out a method of attacking a certain problem, the figures used in the exposition of the method are of secondary importance. It is apparent that no universally applicable figures can be used, because there are none. Each plant has its own coal,2 its own operating cost, and its own conditions.

Jan 1, 1930