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By Ancel St. John

During a session on coal and coke at the February, 1926, meeting of the American Institute of Mining and Metallurgical Engineers, the writer called attention to the important work on the X-ray analysis of coal1,2 being carried on in England by C. Norman Kemp and his associates. This aroused so much interest that a paper on the subject was requested for the October meeting. It has seemed advisable to make this paper a preliminary survey of the present status in the application of X-ray methods to coal problems and to follow it from time to time with further articles as the art develops. A survey of this sort naturally divides itself into two parts, radio-scopic analysis of the distribution of constituents through the body of the coal, and diffraction analysis of the state of association of the elementary components. In this article the subject matter concerning radioscopic analysis has been drawn almost entirely from the writings of Kemp and his associates and the illustrations have been sptcially furnished by him. It is a pleasure to record here a great indebtedness for this courtesy and cooperation. The subject matter and illustrations concerning diffraction analysis are taken from the author's unpublished researches. Nature and Properties of X-rays Before proceeding it is well to recall the nature and some of the properties of X-rays, as well as our present conception of atomic structure According to the accepted theory atoms are composed of electrically-charged particles. A positively-charged center, called the nucleus,

Jan 1, 1927

By Robert T. Howard, Morris Cohen

THE purpose of this paper is to direct attention to the lower part of the austenite transformation diagram, or TTT curves, where considerable uncertainty still exists as to the blending of the bainite and martensite reactions. The dissimilarities between these two low temperature trans- formations have been summarized recently by Troiano and Greninger.1 Of particular importance to the present work is the fact that martensite formation, unlike bainite formation, is not suppressed by the fastest quenching rates attainable. However, most of the investigations in this direction have been concerned primarily with the start of the martensite transformation [(M,)] during cooling, rather than with the quantitative aspects of the subsequent reaction on either further cooling or isothermal holding. Several years ago, Cohen2 suggested a form of transformation diagram which reconciled, at least schematically, the isothermal characteristics of the bainite transformation with the insuppressible nature of the martensite transfoi mation. In essence, the diagram consisted of a family of horizontal lines (representing the progress of the austenite-martensite reaction during quenching) which were interrupted in point of time by the bainite family of C-curves extending down from higher temperatures. This picture received later support by metallographic3 and dilatmetric4,5 studies, but the techniques employed were not sufficiently critical to substantiate some of the details. Elmendorf6 and Grange and Steward7 have shown that the Greninger-Troiano metallographic techniques may be used not only for [M,] determinations, but for studying the course of further austenite decomposition. In fact, the latter investigators have observed the amount of martensite formed as a function of temperature below [M,] in fourteen commercial steels. In the present paper, the Greninger- Troiano technique has been combined with the lineal method of Howard and Cohen9 to provide a unique, quantitative treatment of the austenite-martensite reaction. Furthermore, isothermal transformations have been similarly measured on holding at temperatures above and below M,, thus permitting a fairly detailed presentation of the lower part of the conventional austenite transformation diagram. EXPERIMENTAL DETAILS Materials The steels, listed in Table I, were selected for study because they exhibit a satisfactory range of M, temperatures and have not received as much attention as the lower carbon grades. They were prepared as 30 lb induction furnace heats in the laboratories of the Vanadium-Alloys

Jan 1, 1947

By Chas. H. Behre, Arbiter. Nathaniel

Two outstanding factors characterize most undertakings in the mineral industries: (1) mineral deposits are not equally distributed over the earth but are localized by natural processes, and (2) the mineral industries are largely based upon wasting assets. Neither of these factors is invariably true, for a few mineral materials, such as water, are essentially world-wide and others are replaced periodically by processes not unlike crop production. Indeed, with some, such as the salts in the sea, the supply is cyclic in short or long periods, whereas others, like water, though locally or periodically in short supply, are essentially inexhaustible. But to the extent that most minerals are limited to certain areas and are "permanently" consumed, any industry founded upon them, by implication, demands great care in planning for the most effective extraction-the essence of wise and conservative expenditure. Several less unusual yet also truly fundamental factors in the economics of the mineral industry are those involving (1) the various kinds and properties of mineral materials, which influence their use; (2) their geo- logic and geographic availability; and (3) the techniques unique to their discovery, exploration, and utilization. This chapter is designed primarily as a brief background for later ones and as a summary of the several un- usual or at least special factors and of their effect upon the economics of the mineral industry. The social and political and especially the economic aspects of the industry are the main subjects of this volume and are dealt with in extended fashion in subsequent chapters. Fundamental Characteristics of Mineral Deposits DEFINITIONS Minerals are naturally occurring compounds of nonliving matter, each technically defined as having (1) a chemical composition that may vary

Jan 1, 1959

By Stephen Taber

Introduction.............................. 62 Asbestiform Minerals.......................... 63 Chemical and Mineralogical Relations............... 63 Physical Properties........................ 64 Types of Asbestos............................ 65 Origin of the Fibrous Structure...................... 66 Views of Previous Investigators.................... 66 Discussion of the Evidence.................... 67 Conclusions........................... 69 Origin of Cross-fiber Veins....................... 71 Chrysotile Veins......................... 72 Structural Features of Cross-fiber Veins............... 78 Veins of Crocidolite and Other Fibrous Amphiboles........... 83 Origin of Slip-fiber........................... 84 Origin of Mass-fiber........................... 86 Discussion............................... 87 IntRoduCtion The term asbestos, as commonly used, includes half a dozen minerals all having a well-developed fibrous structure, but differing in chemical composition and in some of their physical properties. In its strict application the name is limited to the fibrous varieties of the monoclinic amphiboles. Commercially, however, the most important of the asbestiform minerals is chrysotile, a fibrous variety of serpentine. About 95 per cent. of the asbestos used in manufacturing is chrysotile, and it commands a much higher price than any of the other fibrous minerals now on the market. Although the production of asbestos has increased rapidly in recent years, comparatively little has been published concerning its origin. The present paper is preliminary in its nature, and therefore does not pretend to exhaust the subject. The ideas herein developed are the result of field investigation, laboratory experiments in the growth of fibrous

Jan 1, 1918

By R. Wachtell

IN order to study better the phenomena at work in various phases of diffusion of the Fe/Si system when compounded and alloyed by powder metallurgy methods, several attacks have been planned. Electrical, hardness and other measurements have been discussed e1sewhere.l,2 The metallographic phenomena will be considered here. Concerning the metallography of the ferrosilicon alloys, some initial discussion is in order. As this laboratory discovered to its chagrin, there are many traps that lie in wait for even the experienced metal-lographer when he deals with alloys of high silicon content. Chief of these is probably the anomalous behavior of these materials under conventional etching techniques. We have before us, for instance, Corson's paper" of 1928, wherein is mentioned and illustrated (probably for the first time) the peculiar "barley shell" structure sometimes found in these alloys. Again in 19412 he same author reports the structure in 5-14 pct silicon irons. Houghton and Becker mention its presence' but make only tentative effort to explain it. In 1943, Hurst and Riley6 discussed the "barley shell" and declared it to be a false structure, resulting from the peculiar and characteristic film-forming propensities of the alloy. At about the same time, Wrazej7 proved correct the contentions of Hurst and Riley, establishing pretty well the mechanisms of formation and identifying the constituents involved. Hurst and Riley6 a1so describe in their paper (1943) a "cracked film" structure, also a pseudo-morph, the precise nature of which they do not suggest. Careful examination of such a film reveals that it not only cracks but begins to curl away from the surface of the metal and peel, much in the manner of flaking paint. The careful microscopist will be able to focus on the topmost edge of the flake, and, by optical sectioning, follow it down to the metal surface. We have been able, by oblique illumination of such specimens, to observe the raised segment of the film, the shadow that it casts, and the mating segment on the metal into which it fits. As late as 1946, Hurst and Riley8 found occasion to correct misinterpretation of this "cracked film" structure in a work by others on a 12 pct Si/Fe alloy. The "barley shell" and "cracked film" pseudo-morphs are not the only ones encountered in studies of these materials. A third pseudomorph, which may, however, have some structural significance is a fine striation of the surface. Closely spaced and parallel striae extend entirely across single grains. Each grain shows a different direction for the striae, and different closeness of the spacing. The regularity of this structure, and the fact that the striae do not cross from one grain to another, suggest that the structure is a film cracking controlled in some way by the crystal plane orientation of the surface being etched. In general it is wise for the metallographer dealing with these alloys to cultivate a feeling of uncertainty not only of the more complex questions of interpretation, but also of the basic question of whether that which he sees is indeed a true representation of the structure. We have taken, as a first test of the validity of a structure, its reproducibility "in situ" after repolishing and re-etching of the samples. Thus we knew the "barley shell" to be false (fig. 1) even before encountering the definitive works on the subject. The Metallography of Silicon Diffusion in Laminate Bars: As a first step in the study of the metallography of the diffusion process, we have pressed a series of laminate bars. These bars, or "sandwiches" as we have termed them, were pressed with covering layers of iron powder, and a "filler" of the Fe/Si master alloy under study. Bar dimensions were approximately %, x 3 x 1/4 in. The total

Jan 1, 1951

By Frank Rieber

THE discovery that strongly magnetic bodies localized near the surface of the earth could be detected by the distortion which they produced in the resultant magnetic field marked the beginning of magnetic surveying methods. From an original ability to detect bodies of magnetic iron ore and the like when located very close to the, surface, these methods have been extended until today they promise to give much information with regard to the structure of such slightly magnetic material as sedimentary rock containing only a very small proportion of iron.1 The recent extensions have been made possible through the development of more delicate instruments, and of methods for their use. From the original compass and dip needle, the design of apparatus has progressed until equipment Is typified by magnetic balances capable of measuring the components of the earth's field to an extremely high degree of accuracy. It seems unlikely that the limit of such instrumental development has been reached. Just as the change from compass and dip needle has enabled the location of relatively minor changes in magnetic materials, so additional developments in the direction of increased sensitivity, as well as in greater dependability and constancy of operation, should reveal positively many slight changes which either escape notice in the present surveys or are so small that they cannot with certainty be separated from uncontrollable errors due to inconstant operation of the equipment. The ability to read smaller and smaller variations does not mean, of course, that deductions as to the causes of these variations will be made as accurately and definitely as -is possible with the more pronounced anomalies.

Jan 1, 1928

By Arne F. Westgren

X-ray analysis and single-crystal study have been utilized in recent years as a new means of following constitutional changes in alloys. If such transformations can be suppressed by rapid cooling, they can be followed at room temperature in a particularly convenient manner. In the following we shall consider changes in solubility and polymorphic transformations with particular reference to phenomena of the age-hardening type. Finally a thermodynamic viewpoint is developed for examining such transformations. Changes in Solubility 1. Determinations of solubility limits in the solid state which show decreasing solubility with falling temperature are made as follows: A series of alloys extending into the heterogeneous region is prepared and quenched fromas high a temperature as possible, whereupon their lattice parameters are determined. Then one or more alloys are quenched from temperatures at which they are heterogeneous and their lattice parameters likwwise determined. For the purpose of determining the parameter the apparatus shown in Fig. 1 has been very useful for it produces sharp films in a short time which can be accurately read. High-order reflections (interferences) from the object are recorded on a film which is placed exactly perpendicular to the X-ray beam. The specimen usually has the shape of a small round bar.l Fig. 2 shows a selection of such exposures of silver-rich Cu-Ag alloys, and Fig. 3 gives the measurements made from these films. Fig. 4 gives the solubility curve which results.2 This curve is shifted to lower concentrations than the curve that is obtained from metallographic or physical methods. The X-ray method unquestionably gives more reliable data

Jan 1, 1931

By F. O. Shuck, F. E. Butler

A diaphragm diffusion cell suitable for use with liquid metals was designed and tested by measuring the diffusion coefficients for a Hg-10 pct In alloy at 25°C. The binary diffusion coefficient and the coefficients for In and Hg tracers were measured at this composition. The measured coefficients for both tracers were less than the binary diffusion coefficient. When these coefficients were combined with the activity correction term of Darken, the predicted binary coefficient was somewhat higher than the experimental value. In recent years a number of investigators have been studying diffusion of liquid metals in order to gain a better understanding of the liquid state and to examine possible applications to liquid metal processing. The bulk of this work has involved either self-diffusion or diffusion of low concentrations of solute metals in an essentially pure solvent metal. The most common experimental technique employed has been the capillary-reservoir method of Anderson and saddington1 since it is well-suited to measurements involving low concentrations of solutes. As an expansion of previous studies, an investigation of the variation of diffusion coefficient over large composition ranges has been undertaken in this laboratory. Although it is possible to modify the capillary-reservoir method for such measurements, the technique loses its principal advantage of requiring only small quantities of solutes. Therefore, it was felt desirable to investigate other possible experimental techniques applicable to measurements over large composition ranges. A technique which has been used widely in measurements of other liquid systems and seemed potentially applicable to studies of liquid metals was the diaphragm cell. This method has been found to combine relative simplicity of operation with accurate and reproducible results. In use with normal liquids, the tyiical diaphragm cell utilizes a porous glass disk. However, because of the high surface tension, it is not possible to use a diaphragm of such fine pore structure with liquid metals. Furthermore. projected use at high temperatures makes the use of glass undesirable. Consequently, the first problem was the search for an appropriate cell design. EXPERLMENTAL Diaphragm Cell. A number of possible cell designs were examined. Prototypes of several were constructed and tested. The final design is shown in an exploded view in Fig. 1. The cell consists of two identical chambers, one on either side of a 0.20-in.-thick partition. The chambers are 0.15 in. deep and have a volume of 3.45 cu cm. Each chamber is provided with two small threaded holes for filling and emptying. The filling holes may be sealed with stainless-steel screws. Drilled lengthwise through the center partition is a 0.250-in.-diam hole. Inserted into this hole is a rod having seven 0.059-in.-diam holes drilled radially through it. The total "hole" volume is 0.078 cu cm. When the rod is properly aligned, the holes in it constitute the "diaphragm" through which diffusion occurs. The center section was of Teflon and the rod and face plates were of Plexiglas. Four such cells were constructed and used in this study. Subsequent to this investigation, a similar cell constructed entirely of iron was fabricated and tested at higher temperatures. Several considerations led to this final design. It is desirable to minimize the volume of the cell chambers to decrease the time required for a measurement. However, the total volume of metal in the diaphragm must be small in comparison with that in the chambers. To facilitate filling and emptying it is desirable to have a diaphragm which may be closed.

Jan 1, 1970

By D. R. Walker, M. C. Shaw

Dimitri Kececioglu (Allis-Chalmers Manufacturing Co., Milwaukee)—The idea of applying metal cutting theory to comminution and vice versa is very impressive. Among others, the demarcation of wheel-grinding data into two regions, namely Kick's and Rittinger's, draws attention here. A study of Figs. 6 to 9 shows the following: In Fig. 6, 1 point out of 8; in Fig. 7, 4 points out of 26; in Fig. 8 only 1 point out of 13; and in Fig. 9 practically none out of 13 points fall out of curve No. 2. Also when grinding particles smaller than 5x10." in. it is difficult to measure very accurately the grinding forces, chip geometry, and particle size. In view of the above it would be difficult to make a positive and distinct demarcation of the Wheel-grinding data into two regions, namely, Kick's and Rittinger's. The idea of using machine grinding to determine the comminution properties of materials is indeed unique. The following cautions come to mind, however, regarding applicability of machine grinding data to comminution: 1—Grinding gives uniform particle size, whereas comminution gives a variety of particle sizes in the same process. The fact that grinding gives uniform particle size is not necessarily an advantage because in comminution the overall energy under actual comminution is desired and comminution invariably results in the production of a variety of particle sizes. 2—In grinding, a small particle is ground off a comparatively large surface. In comminution small bodies are broken down to smaller bodies. This makes it difficult to establish a concept of reduction ratio in machine grinding. 3—The mechanics of machine grinding involve direct shearing action under very high strain and comparatively high compression at the shear zone, whereas: comminution involves direct dynamic compression and surface friction with comparatively little strain and shear. Consequently the mechanics of machine grinding appear to be different from those involved in comminution. Hence one might arrive at erroneous con- clusions when comminution characteristics are eval-uated from machine grinding results. It is noticed also that functions other 'than Eq. 16 which do not involve the concept of direct proportionality of useful energy input to new surface area created (Eq. 2 and particularly Eq. 12) may be derived to fit the, data of curve No. 2. One such relationship may be u = ct-", where c is a positive constant and n is a positive constant less than unity. This, of course, is made possible because data of a very small range. of particle size are being fitted by the curves of No. 2 and the hereby suggested relationship. A sound comminution theory should be applicable to a relatively large range of particle size. George B. Clark (Department of Mining Engineering, University of Illinois)—While the experimental work of Walker and Shawin this article is of intrinsic value in revealing certain fundamental aspects of machine grinding, milling, and related processes and in adding to the store of information concerning the comminution of solid materials by this particular process, it appears doubtful that the results of their research can be employed to verify either Kick's or Rittinger's theories. Both these laws were originally developed and proposed on the basis of very simple, idealized hypotheses. The creation of parallel idealized physical laboratory conditions which would be required for either their proof or disproof appear to be well beyond the scope of human ingenuity, at least at present. One great weakness of the imputed verification is that the spread of the points plotted on the graphs is not sufficient to permit accurate 'curve fitting. The range of particle sizes included in the belt and wheel grinding is not extensive enough to show any general trends, particularly for the horizontal portion of the curves, said to represent Kick's laws. That the milling; grinding, and turning data obtained by Walker and Shaw for both metals and minerals happen to comply with. certain interpretations of these two theories under certain specialized conditions

Jan 1, 1955

By Eugene R. Rice

(Canal Zone Meeting, November, 1910.) THERE are many methods for determining the meridian, but all of those in common use involve at least two separate observations, one for latitude and one for azimuth. Such observations made upon a south star at any hour are open to the objection of possible inaccuracy due to ignorance of the absolute refraction, and also to slow change in the altitude of the star when near the meridian. The method of observing a circumpolar star at elongation, besides requiring a separate observation for latitude, is open to the serious objection that clouds may obscure the star at the critical moment. Moreover, a tedious wait for the star to come to elongation is sometimes necessary. Many of us can recall long, cold, weary vigils, waiting for Polaris to reach elongation. For observing a circumpolar star at any hour, not only the latitude, but also the true time, must be known. This it is practically impossible to obtain, except in regions reached by the telegraph, and usually then one has to know the longitude also, in order to reduce "standard time" to "local time." The results obtained by this method, when the star is at culmination, are not very good, unless the true local time is absolutely known. The methods of obtaining the meridian from the sun, by means of a solar attachment, or by direct observation, while good, are not absolute, by reason of refraction, change in declination of the sun, and small change in vertical angle, when the sun is near the meridian. For these two methods, latitude, time, and approximate longitude have to be known. In the method here described, only one observation is needed, and from it azimuth, latitude, and sidereal time are computed. In other words, one can observe a circumpolar star-Polaris

Nov 1, 1910

By L. H. Levenson, Charles S. Barrett

Plastic flow in metal crystals and the changes in orientation resulting from it are generally understood to take place by the following fundamental mechanisms: (1) slip on crystallographic planes, (2) homogeneous crystal rotation resulting from the slip, (3) bending of the 1attice between the planes of slip, and, under certain circumstances, (4) twinning. This paper and a preceding one on iron subjected to uniaxial compression1 concern two additional processes that must now be added to this list: (5) the formation of deformation bands, and (6) the bending and rotation of these bands. The present investigation yields a new understanding and definiteness to the common terms so loosely used when speaking of cold-worked metals —('grain fragmentation," "elongated grains," and "deformation twins," "deformation bands," "etch bands," or "X-bands." Bands have been noted on the polished and etched surfaces of cold-worked metals by various investigators for more than 25 years, ‡ yet their nature and their significance have been so little understood that they are not treated in the most comprehensive modern texts on the deformation of crystals. The experiments in this series show that they are one of the fundamental processes in the deformation of metals, of importance in the development of preferred orientations, in work-hardening (since they have the effect of reducing the effective grain size and interfering with slip), and in the recrystallization process. The present experiments were performed on the same stock of material that was used in the earlier compression experiments1—hydrogen-purified mild steel in which the carbon content had been reduced to the limit detectable under the microscope and in which single crystals could be grown by a strain-anneal treatment.2

Jan 1, 1939

By C. E. Brown, D. C. Helms, O. W. Shimer

The early history and progress of anthracite stripping, from the first known operation at Summit Hill in 1821 through 1917, was covered in 1917 in a paper by J. B. Warriner,1 then chief engineer, now president of the Lehigh Navigation Coal Co., and stripping methods between 1917 and 1931 were the subject of a paper in 1931 by H. H. Otto,2 of the Hudson Coal Company. . The present paper is confined to methods used today on pitching beds in the western middle and southern anthracite fields. The anthracite industry, not unlike other large industries, had been affected for more than a decade by the adverse economic conditions of the country. High development and operating costs and the competition of other fuels caused some collieries to be closed temporarily, while others were permanently abandoned. In order to obtain a larger tonnage at a lower development cost, a larger stripping program was put into effect by many companies. In 1932, stripping operations accounted for 3½ million tons, or 7 per cent of the total anthracite production of the year, and in the next 10 years this increased until more than double that amount, or over 14 per cent of the total production, was from stripping operations. These figures represent the total production of the entire anthracite region; unfortunately, the figures have not been separated from the different fields. There are some operations in the southern and middle western fields where the tonnage obtained from stripping amounts to more than 30 per cent of the total colliery production. Stripping operations on pitching beds present difficult problems. Owing to the various geological formations, a different situation is encountered in nearly every stripping pit; and because of the proximity of an overlying bed, it is very often necessary to load the entire overburden into trucks and haul it out of the pit to the dump area, although back filling and casting is done whenever possible. Beds in the areas described in this paper pitch from 20" to 90 and some are on the invert in many sharp folds and faults. Planning The more successful strippings have had adequate engineering analysis. Some work is being done without much preliminary planning, but many strippings would have failed completely if close supervision by the engineering department had not been . maintained. Locations of stripping areas are determined as follows: I. By constructing cross sections over the areas and drilling sufficient diamond-drill or well drill holes to study the strata and to determine the location, thickness

Jan 1, 1944

By Charles S. Barrett, L. H. Levenson

Plastic flow in metal crystals and the changes in orientation resulting from it are generally understood to take place by the following fundamental mechanisms: (1) slip on crystallographic planes, (2) homogeneous crystal rotation resulting from the slip, (3) bending of the 1attice between the planes of slip, and, under certain circumstances, (4) twinning. This paper and a preceding one on iron subjected to uniaxial compression1 concern two additional processes that must now be added to this list: (5) the formation of deformation bands, and (6) the bending and rotation of these bands. The present investigation yields a new understanding and definiteness to the common terms so loosely used when speaking of cold-worked metals —('grain fragmentation," "elongated grains," and "deformation twins," "deformation bands," "etch bands," or "X-bands." Bands have been noted on the polished and etched surfaces of cold-worked metals by various investigators for more than 25 years, ‡ yet their nature and their significance have been so little understood that they are not treated in the most comprehensive modern texts on the deformation of crystals. The experiments in this series show that they are one of the fundamental processes in the deformation of metals, of importance in the development of preferred orientations, in work-hardening (since they have the effect of reducing the effective grain size and interfering with slip), and in the recrystallization process. The present experiments were performed on the same stock of material that was used in the earlier compression experiments1—hydrogen-purified mild steel in which the carbon content had been reduced to the limit detectable under the microscope and in which single crystals could be grown by a strain-anneal treatment.2

Jan 1, 1939

By W. N. Miner, R. O. Elliott

Electrical-resistivity )measurments were made be-trueetz room temperatrive and 1.5 oK on five different stocks of cerium metal, and the results were correlated with the types, amounts, and distribution of the impurities present. Magnesium, which appeared to be distributed as a solute throughout the cerium matrix, was found to have a large effect on the residual resistivity, 1 at. pct Mg being sufficient to increase the residual resistivity by about 10 microhm-cm. The formation of ß by repeated thermal cycling between room temperature and liquid-helium temperature is attributed to the deformation and faulting that occurs during the ? D a transformation. In preparation for starting a proposed study of cerium-rich alloys, we examined samples from severa1 stocks of cerium metal in order to choose the purest stock for future use in making the alloys. Low-temperature electrical-resistivity data were used to gain initial information about the purities of the stocks. Additional information was subsequently obtained from chemical analyses, density measurements, optical metallography, and electron-micro-probe analyses. Cerium that has been annealed at high temperature and cooled to room temperature has the fee crystal structure (? phase) with a = 5.16Å. When cooled further, in the region between about 250" and 150°K, some of the fee phase transforms to the double hcp form (ß phase) with a = 3.68 and c = 11.92Å. The remainder of the room-temperature fee form (and perhaps some of the hexagonal phase) transforms electronically in the vicinity of 100° K to the more dense or "collapsed" fee form (a phase), a - 4.85A, by transferring about 0.5 electron per atom from the 4f level to the valence band. Very little work related specifically to the effects of impurities on the physical properties of cerium has been reported in the literature. Gaume-Mahn1, 2 has studied the effects of calcium, magnesium. iron, silicon, and tantalum on the electrical resistivity and magnetic susceptibility of cerium between 60o and 300°K. Gschneidner, Elliott, and McDonald3 have discussed the effects of total impurity content on the hysteresis of the a —? (reversible) transformation and on the formation of the 4 and "a-? intermediate" phases. Smith and Morrice* have reported the effect of total impurity content on the resistivity of cerium at 4 and 293°K. In none of these reports, however, is it apparent that the distributions of the impurities were determined, L.r., whether the impurities were present in inclusions or in solid solution in the matrix is not mentioned; nor does it appear that the phase purity of the cerium was always considered. In the present study, five different stocks of cerium were involved. One was represented by a single sample of electrowon cerium, which was all that had remained from a stock of high-purity material obtained from the U.S. Bureau of Mines, Reno, Nev., in 1959. The other four stocks were recently purchased from commercial sources and were specified to be 99.9 wt pct pure. EXPERIMENTAL Cerium stocks designated as #1, #2, #4, and #5 were obtained from commercial suppliers for the specific purpose of finding a reliable source of high-purity cerium. Although the purity level of the cerium was specified to be 99.9 pet, the specifications did not include limits as to the amounts of various impurities that would be acceptable. Consequently the chemical analyses of the different stocks varied widely. Stock #3, which had been obtained from the U.S. Bureau of Mines and which was the purest on the basis of chemical analyses, consisted of a single specimen of electrowon cerium. It was included in the examination for purposes of comparison. Table I contains the chemical and spectrographic-

Jan 1, 1968

By S. S. Clarke

LATE in 1942, the increasing demand for zinc, coupled with the growing shortage of miners and the knowledge that some abandoned mines would have to be reopened for prospecting and development, led to considerable thought as to the possibilities of further mechanization in order to conserve man power. The ore bodies, locally termed "sheet ground," are an important ore bed in some mines and are in the lower part of Boone formation of the Mississippian Series. Some mines contain interbedded layers of nearly pure galena and sphalerite in horizontal sheets ranging in thickness from a thin seam to several inches and is persistent over large areas. This type of ore body offered the best opportunity for study and experiments. The use of jumbo drill carriers was advanced but some doubt was expressed as to the adaptability of jumbos as then in use to mine headings as compared to post and arm mounting (Fig I). Another consideration was the introduction of truck haulage when several mines were trackless. A drill frame, built to carry 2 4-in. drifters, was mounted on a truck chassis. This design proved a failure as it was not rigid and the resiliency of the tires and springs allowed too much play. Long screw jacks were then used to hold the truck firmly in place, but placing the jacks and securing the truck required more effort and time than setting up post drills, so the truck carrier was abandoned. The use of a bull dozer underground had been under consideration for some time to be used in "brunoing" the broken dirt from behind pillars and other inaccessable places so the slusher drags could load without double dragging the dirt. A dozer with hydraulic blade lift was purchased and R. I. Tuthill, Superintendent of Section 30 Mines, suggested that a long drill arm be substituted for the blade, and the drills mounted on the cross member. The hydraulic lift would permit drilling holes at any required spacing. The "cat" was very mobile and answered the problem of a trackless mine. The initial tests showed that the "cat" would make a good carrier, but the hydraulic controls Were not positive enough to keep the drills in alignment while drilling. The next step was to build a small hoist. This hoist was attached to the power take-off on the "cat" and by means of sheaves and a double line of 3/8-in. hoist cable, a positive control for raising and lowering the boom was obtained. To avoid serious injuries to the drillers should the cable break, a safety chain was fastened to the drill boom and hooked into a slot in the back of the "cat" frame. A different power unit was obtained for the "cat," as a state law prohibited the use of internal combustion engines in mines. A custom machine shop had just placed on the market a small hoist powered by a Model A Ford engine that had been very ingeniously converted to a slide valve engine using compressed air. To use this unit on a "cat," our master mechanic de-

Jan 1, 1947

By R. H. Hadfield

Professor ArnolD, of the Sheffield Technical School, who has done so much excellent work in metallurgical research, recently produced, with the aid of aluminum, a sound ingot and bar from the purest known Swedish brand containing 99.8 per cent. of pure iron. Table 1. shows the physical quantities of this metal. TABLE I.— Tests of a Sample of Almost Pure Iron Prepared by Professor Arnold from D. v Ewedish Bar, Containing Before Fusion 0.04 Per Cent. of Carbon. I. II.+ III. Series mark,.. 136 1.371F ...... C, 0.07 0.07 Si, 0.04 0.04 8, 0.02 0.03 ...... Analysis, per cent,. .. P, 0.02 0.015 ...... Mn, 0.06 0.07 Al, 003 ............ Fe, 99.76 99.81 ...... Specific gravity,........... 7.863 ...... Original diameter, inches,. .. 0.564 0.798 0.798 Original area, square inches,. . 0.25 0.50 0.50 Limit of elasticity, tons per square inch,...... 18. 3.8 Breaking-load, tons per square inch,. 21. 23. 14.75 Total elongation, per cent., measured on 2 in.,...... 50. 49.25 61. Total reduction of area, per cent.,. 80. 69.60 61.20 Extension at permanent set, per cent.,...... 0.007 ...... silky and Appearance of fracture,. .. . silky i granular in parts.

Jan 1, 1894

By Robert H. Richards

This is in part a review paper, indicating the various steps that have been taken in developing hindered-settling apparatus, some of the standard data that have been obtained, and some of the conclusions one is led to as to the effect of it in improving concentrating-methods and machinery, and in part it brings in some unpublished work. Causes oF Loss in ORe-ConcEntration. In making a study of the separation of valuable minerals from the waste gangue, particularly by water concentrators, it is necessary to define, first of all, what are the causes of loss that are likely to interfere with the concentration. Having made this definition, we can then study to see in what may the machines make their losses, and plan remedies for them in an intelligent way. Losses may be stated to occur as included grains, as flat or long grains, as fine free mineral, and as absolute slime. We will take these up one by one, as follows: Included Grains.—Fig. 1 shows by a set of diagrams how included grains may occur : first, where the heavy mineral grains attached to the quartz are of large size; secondly, where they are of small size; and thirdly, where very fine particles of heavy mineral are included in the quartz. We have to decide in regard to included grains whether they are rich enough to go direct to the furnace, or poor enough to throw away, or whether they lie between these two points and require recrush-ing as the only means of severing the values from the waste. This last case is the orlly one requiring special treatment at our hands. We will therefore consider that next.

Jan 1, 1911

By Jack A. Simon, M. E. Hopkins

Coal is defined as a combustible rock that originated in the accumulation and physical and chemical alteration of vegetation. Coal can be ignited and burned like the wood that was man's earliest fuel, but coal gives more heat than the same amount of wood and has many industrial uses. Unlike wood, coal is not generally found on the surface of the ground but is mined from the solid rock of the earth. Before taking up the occurrence, formation, and the unique character of coal in the rock sequence, let us briefly consider the general character of all rocks in the crust of the earth. Relatively little is known about the very earliest history of the earth, although a number of logical theories have been developed. Manned exploration of the moon and the rocks returned to earth continue to provide some answers to questions concerning the earth's origin and history. The period of earth history with which we concern ourselves here begins after great areas of water had evolved on earth and substantial land areas of once molten (igneous) rock existed. Weathering and other processes that attacked the surface of the rocks reduced them to small particles. Water provided by rainfall transported this material, ultimately, to large bodies of water where it was deposited. Thus was initiated the geologic sequence of sedimentary rocks that lie above the once molten igneous rocks. The crust and upper mantle of the earth are made up of several large plates along which differential movement (primarily horizontal) takes place. Such movements, although small, are occurring today. These horizontal movements are accompanied by vertical movements causing important changes in the relative position of the continents and oceans. Low-lying coastal swamps with favorable climates are ideal locations for coal accumulation and burial by river-borne sediments, and large areas

Jan 1, 1981

By Ralph W. Smith

DEVELOPMENT of the lime industry- in Ste. Genevieve County began in a crude way in 1840. According to information furnished by the Missouri Bureau of Geology, in the early days small vertical kilns built of stone were used, and wood was the fuel. Modern development began in 1904 when one company introduced steel shells lined with firebrick. Within a few years two more companies erected similar plants, and in 1925 a fourth company began operations. Thus there are today four lime companies at Ste. Genevieve, all operating at high capacity and with a gradually increasing production. GEOLOGY The limestone of Ste. Genevieve County, which has the chemical composition and purity required for lime burning, is the upper 80 or 90 ft. of Spergen formation. The Missouri Bureau of Geology, in its geological map of Ste. Genevieve County, gives the Spergen formation a total thickness of 160 ft., but only the upper portion is pure enough for lime burning, with an average raw-stone analysis of 98.7 per cent CaC03; 0.35 Si02; 0.3 R203; 0.35 MgCO3; 0.3 S03. The Spergen, one member of the Meramac group, Iowa series, of the Mississippian system, underlies an area approximately 12 miles long north and south, by 5 miles wide east and west (Fig. 1) in Ste. Genevieve County. The entire eastern two-thirds of Ste. Genevieve County is sedimentary, the formations dipping gently toward the east on an average grade of about 4 per cent, or 2 ½ º. Thus the outcrops of the various sedimentaries run approximately north and south. A line running west from Ste. Genevieve crosses the outcrops of the sedimentaries, ranging from the top of the Mississippian to the Ozarkian geological system in a space of 12 miles. Thus with the gentle dip of 2 ½ º the 160-ft. thickness of the Spergen formation stretches out in its outcrop so that it is approximately one mile

Jan 1, 1938

By Rudolf Gahl

Page Tests Conducted in Small Test Mill................... 577 Demonstration Tests Conducted by Minerals Separation Co....... 577 Flotation Tcsts Conducted by Inspiration Co............. 577 Sampling of Orebody........................ 578 Other Results Obtained in Small Test Mill.............. 580 Tests Conducted in Large Test Mill................... 580 Flow Sheet............................. 580 Discussion of the Value of Preliminary Table Treatment......582 Callow Flotation Installation..................... 585 Flinn-Towne ~nstallation...................... 587 Cole-Bergman Installation...................... 588 Methods Followed in Competitive Tests................ 590 Advantage of Pneumatic Flotation Machines.............. 591 Pneumatic Machines of Minerals Separation Co............. 591 Float Skimming Device......................; 594 Experimental Inspiration Flotation Machine.............. 596 Arrangement of Callow Cells in Series ................ 598 Variations of Flow Sheet....................... 599 Coal Tar as Flotation Agent..................... 600 Experience with Primary Slime.................... 602 Influence of Iron on Flotation..................... 605 Influence of Chemicals on Primary Slime............... 607 Fineness of Crushing Desired.................... 607 Operation of Large Concentrator..................... 608 Flow Sheet of Callow Sections.................... 608 Flow Sheet of Inspiration Sections.................• 609 Inspiration Flotation Machine of Steel Construction.......... 610 Minerals Separation Section..................... 613 Filter Plant............................ 613 Results Obtained in Commercial Concentrator............... 616 Tonnage............................... 616 Air and Power Consumption...................... 616 Floor Space............................ 617 Water Consumption......................... 617 Recovery............................. 618 Oil Consumption.......................... 618 Operating Costs for Flotation..................... 620 Discussion of Results Obtained.................... 620 Prospects for Futurc Development of the Flotation Process......... 621 Porous-Bottom Experiments..................... 622 Raising the Grade of Concentrates.................. 624 Recovering Carbonates by Flotation................. 624 Recovery of Silicates by Flotation.................. 627 General Theory......................... 628 Conclusion............................... 630

Jan 1, 1917