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By Frederick Laist, Howard Aldrich

The object of the construction and operation of the 80-ton leaching plant was to test out the leaching of sand tailings on a large scale and, if possible, determine a definite method of operation, and the best construction for the larger unit which is now being built. It was also of importance to obtain some practical data as regards cost items. The 80-ton plant was not expected to be a commercial success. A leaching process on such low-grade material necessitates the treatment of a very large tonnage. Such a cost item as labor, for instance, is entirely out of proportion in such a small plant. The amounts of acid, salt, scrap iron, and fuel for roasting, however, are the same per ton in an 80-ton plant as in a 2,000-ton plant. These costs were definitely established. Also the percentages of extraction and grade of tailings were definitely determined for a large-sized unit. Following will be found the description of the plant, the method of operation and the- results obtained. A general view of the plant is given in Fig. 1. The bins consisted of one coal bin with a capacity of 30 tons, one salt bin with a capacity of 20 tons, and a "mill tailings" or feed bin which held 70 tons. The coal and salt bins were placed with their floor level even with the firing floor of the roasting furnace. The feed bin, to give it greater capacity, discharged about 12 ft. below this point, to a 12-in. conveyor belt, which in turn discharged into a pug mill. This fed another conveyor belt, which discharged into the top hearth of the furnace. The furnace was an ordinary six-hearth MacDougall roaster, 20 ft. in diameter. It was equipped with two fire boxes, on opposite sides, the flames entering on the third hearth. An induced draft was obtained with a Buffalo blower, worked as an exhaust fan. Just above the top hearth was an annular flue around the whole circumference of the furnace. Slots at intervals of about 18 in. led from this flue down into the top hearth. The slots were 2 in. wide by 6 in. long. This annular flue proved rather unsatisfactory, as it tended to fill up with flue dust and choke the dots, thus cutting down the draft. The volume of gas through

Jan 1, 1915

By D. G. F. Hedley, D. F. Coates, K. Barron

INTRODUCTION Preceding papers presented in this symposium have considered the influence of various parameters, such as geologic structure, groundwater, etc., on the stability of rock slopes and have given some analyses and guide lines for slope design. To carry out such analyses it is necessary to put numbers to these parameters; where possible, this is best done on the basis of in- situ observation and measurement. Since none of the design analyses can be considered exact and since conditions vary during excavation, it is also desirable to monitor the behaviour of the slopes as the excavation proceeds. In this manner a feedback of information on the actual excavation conditions can allow a continuous reassessment of the design parameters to be made and can give early warning of incipient failures. The purpose of instrumenting rock slopes is thus to provide information which fits into one of two categories: (a) To give basic data to assist on-site assessment and design of the rock excavation. (b) To provide data for the control and assessment of safety during excavation. The purpose of this paper is to review briefly some of the instruments and measuring techniques available for gathering this data and to indicate where such data may prove useful. This is not a comprehensive review of all available instrumentation but, rather, is a survey of some of the instruments and techniques with which the authors have had some experience and which have proven useful. STRUCTURAL ASSESSMENT Whilst most structural assessment of a site is done on the basis of geologic mapping and core examination, there exists some instrumentation which can, in particular circumstances, assist in this assessment. Seismic instruments can be used to determine the geometry of formations and to give an indication of the relative competency of rocks. These instruments operate using seismic reflection or refraction techniques and, although mainly confined to shallow sub-surface exploration, can be useful in distinguishing between soil/ bedrock contacts and, in some cases, the extent of weathered surface rock.

Jan 1, 1971

By Russell G. Wayland

This paper gives the author's personal idea of the general viewpoint of the world's largest mica consumer, the U. S. Army, toward the supply, uses, and conservation of mica. However, to cover so broad a subject in a brief paper will require the dismissal of many phases with little or no mention. For example, it will be necessary to omit further reference to phlogopite or amber mica, even though amber block and splittings for certain spark plugs and commutator segments present some supply problems. This paper will deal entirely with muscovite, or white mica. Muscovite Mica Muscovite mica is available commercially in four general forms; namely, as block mica, as splittings, as washer punch, and as scrap mica.1 No strategic importance is attached to washer punch and scrap mica, even though scrap has found some use in military construction and in electrical ceramics. The use of washer punch as such has fallen off with the non-manufacture of household electrical appliances. Some qualities of block mica are also of little or no interest, but other qualities of block mica and all splittings are considered of vital importance. Army equipment requires large amounts of muscovite mica splittings in the form of built-up mica commutator segments and coil insulation in motors and generators. Other military items using significant amounts of muscovite splittings are transformers, switchboards, and blasting apparatus. Flexible mica tape, made from bookform or loose-dusted splittings cemented to paper, linen, glass cloth, and other backing, is widely used in coil insulation in heavy electrical equipment and in aircraft generators. All muscovite mica splittings come from India, principally because of the enormous amount of hand labor required in their preparation. In this emergency, the need for them was anticipated and large industry and government stocks were on hand, while shipments have continued to come by sea in spite of wartime hazards. With the possible exception of certain bookform splittings, no trouble is anticipated in supply. Accordingly, the remainder of this paper is devoted to block (or sheet) muscovite mica, including condenser film that is split from block. The Mica Problem Block muscovite mica is commercially classified into the following general qualitie3, beginning with the best quality: 1. Clear and Slightly Stained (C & SS). 2. Fair stained (FS). 3. Good stained (GS). 4. stained (s). 5. Heavy Stained (HS). 6. Black spotted. The ratio of relative commercial abundance in the present new supply of these micas is approximately 1 C & SS to 4 FS to ro GS to 14 S to whatever the

Jan 1, 1948

By Russell G. Wayland

This paper gives the author's personal idea of the general viewpoint of the world's largest mica consumer, the U. S. Army, toward the supply, uses, and conservation of mica. However, to cover so broad a subject in a brief paper will require the dismissal of many phases with little or no mention. For example, it will be necessary to omit further reference to phlogopite or amber mica, even though amber block and splittings for certain spark plugs and commutator segments present some supply problems. This paper will deal entirely with muscovite, or white mica. Muscovite Mica Muscovite mica is available commercially in four general forms; namely, as block mica, as splittings, as washer punch, and as scrap mica.1 No strategic importance is attached to washer punch and scrap mica, even though scrap has found some use in military construction and in electrical ceramics. The use of washer punch as such has fallen off with the non-manufacture of household electrical appliances. Some qualities of block mica are also of little or no interest, but other qualities of block mica and all splittings are considered of vital importance. Army equipment requires large amounts of muscovite mica splittings in the form of built-up mica commutator segments and coil insulation in motors and generators. Other military items using significant amounts of muscovite splittings are transformers, switchboards, and blasting apparatus. Flexible mica tape, made from bookform or loose-dusted splittings cemented to paper, linen, glass cloth, and other backing, is widely used in coil insulation in heavy electrical equipment and in aircraft generators. All muscovite mica splittings come from India, principally because of the enormous amount of hand labor required in their preparation. In this emergency, the need for them was anticipated and large industry and government stocks were on hand, while shipments have continued to come by sea in spite of wartime hazards. With the possible exception of certain bookform splittings, no trouble is anticipated in supply. Accordingly, the remainder of this paper is devoted to block (or sheet) muscovite mica, including condenser film that is split from block. The Mica Problem Block muscovite mica is commercially classified into the following general qualitie3, beginning with the best quality: 1. Clear and Slightly Stained (C & SS). 2. Fair stained (FS). 3. Good stained (GS). 4. stained (s). 5. Heavy Stained (HS). 6. Black spotted. The ratio of relative commercial abundance in the present new supply of these micas is approximately 1 C & SS to 4 FS to ro GS to 14 S to whatever the

Jan 1, 1948

By David R. Mitchell, E. A. Reilly, G. R. Gardner, F. P. Lasseter

THE methods that may be applied to the treatment of slurries and water, as these are related to practical coal-preparation problems, are concerned essentially with the movements of solids suspended in water. It is assumed that there are no fundamental differences between the principles involved in the treatment of coal slurries and the phenomena encountered in general mineral-dressing practice, and the latter are-presented in some detail. Basic principles are correlated with present practice for both the anthracite and the bituminous coal fields, and methods are discussed which are designed to utilize best all the material subjected to treatment and suggest a sound approach to the solution of problems relating to the return of clear water to process or to streams. In order to approach the practical phases of the subject with sufficient understanding of the basic principles, it is necessary to discuss two types of phenomena that are applicable. The first is flocculation and the second is sedimentation. Descriptive matter is given covering the various methods and types of equipment employed to conduct these operations, with emphasis on their application to water and coal-slurry treatment. DEFINITION OF TERMS Definitions of terms are consistent with modern developments, and conform, in general, with their usage in mineral-dressing practice. Because of variations in coal-preparation methods, it is impossible to define a rigid upper limit of particle size for a coal slurry or sludge which will apply generally. Limits vary somewhat with the particular treatment method employed at a given plant. For purposes of definition, this limit is chosen as the particle size for which preparation methods such as Chance comes and jigs are usually dispensed with, and other methods, such as the Hydro-tator, tables, and froth flotation, are employed. Generally the limit will be 10 to 6 mesh.

Jan 1, 1950

By Carl Allen

INTRODUCTION IN any discussion of mining one is repeatedly confronted with the difficulty of dealing with so many variable conditions. It is not an exact science and in the choice of a method each varying factor has a certain weight, which, in many cases, experience alone can determine. In mathematical terms, it is a function of many variables. A discussion of mining also loses much of its value unless, costs are considered, because the expectation of profit is the only excuse for carrying on mining at all. As conditions vary they cause fluctuations in cost and there are few operations to which a definite cost can be assigned. The character of the ore may make it difficult to drill, yet because of the ease with which it breaks the total cost of drilling and blasting may be low. In preparing this article the attempt has been, not to cover the whole field of mining, but to describe the different methods of stoping and mining which have distinct principles. In addition to this an effort has been made to show the advantage of dissecting the methods into their detailed operations and applying to these a mathematical study as an aid to the judgment in determining which is the best method to adopt, or in attempting to reduce the cost of a method already in use. Methods of mining include stoping, caving, and various methods of working large deposits which, in addition to the method of actually breaking the ore, require elaborate and definite plans of, development of the orebody. The ordinary methods of stoping are too familiar to all for any elaborate discussion, but it has seemed advisable to review the subject and give the principal advantages' and disadvantages of the different methods.

Jan 8, 1914

By H. H. Stoek

Danville, the county seat of Montour county, Pa., was one of the earliest and best-known centers of the iron intlustry in the State. It is situated on the north bank of the north branch of the Sosquehanna river, twelve miles east of the confluence of the north and west branches of that river at Northurnberlttnd. The ore-belt, extending for a distance of twelve miles along the north bank, has been developed in a number of places, but nowhere so extensively as in the immediate vicinity of Danville. Hence, a description of the mines in that locality will suffice, as typical of the workings of the entire section. Geology. The Montour ridge consists of an anticlinal fold extending from the source of Wapwollopen creek on the east to the west branch of the Susquehanna, which it reaches at the mouth of Chilisquaque creek. According to the reports of the First Geological Survey of Pennsylvania, the length of the ridge is nearly twenty-seven miles, with an average breadth of three-fourths of a mile, and a maximum elevation of six hundred feet in the vicinity of Danville, where it also attains its greatest width. Just north of Danville the Mahoning creek cuts through it, exposing the iron-ore on the hill-side, where advantage has been taken of this to work the beds on the southern slope of the ridge by means of drifts. The sections given in Fig. 1 are taken from the reports of the First Geological Survey of Pennsylvania, made in 1858, by H. D Rogers, whose description of the Moatour ridge was so complete and accurate that the entire report was reprinted as an appendix to Vol. G 7 of the Second Geological Survey. The approximate crosssection shows that near Danville the top of the ridge is of Clinton vol, xx.—24

Jan 1, 1892

By James J. Scott

INTRODUCTION This paper presents the basic principles which must be followed to create a truly inherently safe mining system. The need to relate the support mechanism to be employed to the ground reaction curve and basic rock mechanics principles will be pointed out. The support system must function in concert with the deformations that are inherent in the selected mining system. Following the support selection, the mechanics for installing support must be developed. This is best done through a cooperative effort between mine engineers, mine operators, safety personnel, equipment sup- pliers, and government inspectors both state and federal. Accident statistics, near miss statistics, review of equipment used by others, geologic features, etc. will necessarily have to be studied. The goal of equipment development and selection should be to develop inherent safety by removing the miner from the hazard area or by providing absolute protection for the miner if he must work in close proximity to the potential fall of ground. The role of good productivity in reducing the numbers of men exposed to hazards is emphasized as a good safety measure ROCK MECHANICS PRINCIPLES A thorough understanding of the ground reaction curve surrounding openings to be created is essential in the

Jan 1, 1982

By Frank S. Gardner, Morris Cohen, Dara P. Anita

There is a conspicuous lack of information in the literature on the precise role played by residual quantities of austenite in heat-treated steels. While retained austenite may be expected to have significant effects on such important properties as the impact resistance of tools and carburized parts and the dimensional stability of dies and gauges, attempts to study these problems systematically have suffered from the absence of a reliable technique for ascertaining absolute amounts of austenite. With such a technique, not only could the relation between residual austenite and service behavior be investigated, but the chemical and heat-treatment factors that control the quantity of the austenite could also be established. Thus, the retained austenite content could then be regulated in accordance with the results desired. The presence of retained austenite may be inferred by observing the changes in properties (hardness, specific volume, electrical resistance, etc.) due to its decomposition on subatmospheric cooling1 or on tempering,2 but these indirect measurements are not readily translated into percentages of austenite. Quantitative determinations have been achieved in special cases by means of dilatometric3 and magnetic4,5 measurements; but the former procedure requires that observations be conducted during the hardening and involves difficult calibrations that limit its applicability, while the magnetic procedure is very sensitive to extraneous influences and depends upon assumptions that can only be considered as approximate in an absolute sense. Furthermore, both the dilatometric and magnetic effects are volume properties, and cannot be conveniently utilized to explore variations in retained austenite from point to point in a suecimen. Some microstructures lend themselves to accurate evaluation of retained austenite contents by metallo-graphic methods,3 but such instances are not too common, and at best, the procedure is tedious. The characteristic X-ray diffraction lines of austenite permit positive identification of its presence; and in the present paper the intensities of these lines, or the corresponding densities* on photographic film, are employed to measure the amount of the retained austenite. In order to cancel the effect of uncontrollable variations in the X - ray exposure and film - development conditions, a standard reference line is Superimposed on each film by maintaining a foil of aluminum in the path of the incident X-ray beam during the entire exposure. With different samples of steel and the same foil, the ratio of the density of some one austenite line to the density of

Jan 1, 1943

By J. T. Berling, J. B. Conway

MANY studies have been devoted to the correlation of low-cycle fatigue behavior. Several of these have also been concerned with the identification of an effective approach to the prediction of low-cycle fatigue behavior from short-term tensile data. Perhaps the first such approach was that reported by coffin1 in the form: where is the plastic strain range, Nf is the number of cycles to failure, and c is a constant characteristic of a material. In this analysis by Coffin it was reasoned that in a short-term tensile test the value of Nf could be considered as equal to a , in which case the value of c is interpreted as the tensile ductility, f, measured in such a test. If, therefore, the Coffin equation is assumed to be applicable to a given material, it is a simple matter to predict the low-cycle fatigue behavior. Once the tensile ductility is known, this point is located at Nf = 1/4 on a log-log plot of vs Nf and a line is drawn through this point with a slope of to yield a prediction for the fatigue life. Actually, while this equation is quite useful it is not generally applicable, for experiment has shown that the value of —$ does not reflect the relationship between and Nf for all materials or even for a given material over all temperature ranges. An equation similar to the Coffin equation was prepared almost simultaneously by Manson.2 This expression had the form: In this case the exponent on Nf was not assigned any particular numerical value in accord with the various values of this exponent which had been observed for different materials and at different test conditions. Because of this characteristic it will be recognized that little use can be made of this expression in predicting low-cycle fatigue results. A fairly effective expression for use in predicting fatigue behavior was proposed by Manson3 based on a study of numerous sets of experimental results. This relation (Method of Universal Slopes) makes use of modulus of elasticity, ultimate strength, and tensile ductility, and assumes an exponent on Nf equal to 0.6 in representing the plastic strain range contribution to total strain range. While this equation of Man-Son does not yield completely accurate results it must be recognized as being the best means available at

Jan 1, 1970

By Morris Cohen, Dara P. Anita, Frank S. Gardner

There is a conspicuous lack of information in the literature on the precise role played by residual quantities of austenite in heat-treated steels. While retained austenite may be expected to have significant effects on such important properties as the impact resistance of tools and carburized parts and the dimensional stability of dies and gauges, attempts to study these problems systematically have suffered from the absence of a reliable technique for ascertaining absolute amounts of austenite. With such a technique, not only could the relation between residual austenite and service behavior be investigated, but the chemical and heat-treatment factors that control the quantity of the austenite could also be established. Thus, the retained austenite content could then be regulated in accordance with the results desired. The presence of retained austenite may be inferred by observing the changes in properties (hardness, specific volume, electrical resistance, etc.) due to its decomposition on subatmospheric cooling1 or on tempering,2 but these indirect measurements are not readily translated into percentages of austenite. Quantitative determinations have been achieved in special cases by means of dilatometric3 and magnetic4,5 measurements; but the former procedure requires that observations be conducted during the hardening and involves difficult calibrations that limit its applicability, while the magnetic procedure is very sensitive to extraneous influences and depends upon assumptions that can only be considered as approximate in an absolute sense. Furthermore, both the dilatometric and magnetic effects are volume properties, and cannot be conveniently utilized to explore variations in retained austenite from point to point in a suecimen. Some microstructures lend themselves to accurate evaluation of retained austenite contents by metallo-graphic methods,3 but such instances are not too common, and at best, the procedure is tedious. The characteristic X-ray diffraction lines of austenite permit positive identification of its presence; and in the present paper the intensities of these lines, or the corresponding densities* on photographic film, are employed to measure the amount of the retained austenite. In order to cancel the effect of uncontrollable variations in the X - ray exposure and film - development conditions, a standard reference line is Superimposed on each film by maintaining a foil of aluminum in the path of the incident X-ray beam during the entire exposure. With different samples of steel and the same foil, the ratio of the density of some one austenite line to the density of

Jan 1, 1943

By Marvin Lee

Kansas retained, for the eighth consecutive year, the fourth position in the list of oil-producing states. The total crude-oil production during 1934, as reported by purchasers to the State Corporation Commission, was 45,538,564 bbl. on 97 per cent tank table calculations of the purchasers, or 46,946,973 bbl. as carried on 100 per cent measurement in U.S. Government reports. The corresponding figures for 1933 are 40,008,940 and 41,236,021, respectively. The increase of production over 1933 was due to the rising demand for oil from Kansas, caused principally by three factors: the continued regulation of the producing branch of the industry by Federal and State authorities, which had the effect of reducing illegal production that has been so destructively competitive with Kansas crude and refined products; the normal decline of production in other areas; and, last and best, general increased demand of the public for petroleum products. The price level remained unchanged for the first time in oil history for so long a period. Kansas 36" gravity crude remained at $1 per barrel from September, 1933, and throughout 1934. Price stability and the confidence in the regulation of production to meet the consumer demand, which is increasing, brought greatly renewed interest in Kansas fields. Drilling activity has been largely in the western part of the state where expiration of leases, on large blocks of acreage, assembled before the depression, is forcing either action or loss of the lease investment carried for a long period. The drilling of these many blocks of acreage, previously assembled on geologic information, has caused the opening of more fields than during any previous year of Kansas oil history and is proceeding faster than anticipated a year ago. Interest grows within a successful enterprise, and the momentum caused by the successes of 1934 will continue in 1935 unless unusual conditions arise and end the apparently good opportunity for financial return. Geological exploration methods used in new field discoveries are shown in the tabulation of new discoveries (Table 3).

Jan 1, 1935

By G. F. Jenkins

The word asbestos is a broad term that has been accepted and applied to a number of fibrous mineral silicates found in nature. They are incombustible and can be separated by mechanical means into fibers of various lengths and thicknesses, but differ in chemical composition and other properties. It is generally recognized that there are six varieties of asbestos; the finely fibrous form of serpentine known as chrysotile, and five minerals of the amphibole group, i.e., amosite (not fully recognized as a mineral species name but accepted in asbestos terminology), anthophyllite, crocidolite, tremolite and actinolite. (Figs 1-4.) Physical and Other Properties The structures of asbestos fibers have been studied intensely in recent years. X-ray diffraction patterns 1 to 15 have been used as a means of identification and classification. The amphibole group structures have been fairly well established while the serpentine group has been the subject of many investigations during the past six years. Low-angle X-ray scattering techniques5 have shown that the chrysotile fibrils are "hexagonally close packed" and parallel to each other, having cross-sectional diameters varying from 180Å* units to 300Å units, while the amphibole fibers are many times larger in cross section. The electron micrographs of chrysotile asbestos (Figs 1-4) have also indicated that the fibrils might be in the form of a hollow tube. This point has been the subject of considerable controversy by a number of investigators.7 to 16 Density measurements17 made on a sample of high quality Arizona fiber did not indicate that the fiber had a hollow tube structure; however, the so-called "sheet structure" of the fibril could be distorted in such a way that it gives the appearance of a hollow tube in the electron microscope. It is of interest to quote one investigator, F. L. Pundsack,17 in this connection: Although the empirical composition of chrysotile is 3MgO.2SiO2.2H20, the true unit cell[#] composition is best represented as Mg12(OH)16Si8O20. This cell has dimensions of a= 5.3Å, b = 9.2 Å, and c = 14.6 Å where the "a" direction is the fiber axis. The calculated density of this unit is 2.56 g/cc, a value in close agreement with experimentally determined density values for chrysotile. The exact manner in which the unit cells of asbestos are stacked together to build up a single fiber of chrysotile is not known, but from various

Jan 1, 1960

By T. A. Wilson, S. L. Hoyt

THE plastic deformation of slender single crystals of zinc has been described in some detail in the paper by Mark, Polanyi and Schmid,1 which has become a classic, and also by one of the present authors in a somewhat shorter account.' The study of single-crystal zinc is termed classical because zinc single crystals offer, perhaps, the best material yet available for the study of atomic behavior during deformation and the effect known as "strengthening" in metals. A considerable amount of additional work has also been done on single-crystal zinc, but as it is not closely related to the present paper it will not be considered. Throughout all the former work, the mechanism of plastic deformation first described by Mark, Polanyi and Schmid has been assumed to hold. This may be said to offer the strongest confirmation of its correctness. Even so, the picture of the process has never been as completely portrayed as is desirable. The first object of the present paper is to describe work that has been done in this field, and which is even yet being carried on, in the hope that a more complete picture may be obtained. Mathewson and Phillips' have recently described a new mechanism of the deformation of zinc based on their study of large rectangular crystals. One of their conclusions was that deformation produced twinning with a rotation of some of the basal planes into positions 94° removed from their original position; a position almost the same as that of the prismatic planes before twinning. A second conclusion was that fracture occurred along these basal planes in their new position, and, therefore that fractures previously regarded as prismatic were in reality basal. Such findings are of great significance and they raise a question as to the generality of such behavior. Professor Mathewson's opinion is that even the slender cylindrical single crystals behave in the same manner as his large rectangular crystals when strained by simple tension.

Jan 1, 1928

By Donald O. Rausch, Adolph Soderberg

4.1-1. Introduction. Open pit mine planning must be correlated to all phases of a mining operation. The factors that must be considered in planning an open pit mine are numerous and must reflect the characteristics and surrounding conditions of a particular orebody. Therefore, only an outline of the subject can be presented here to aid the planning engineer in pointing out procedures that are generally applicable to pit design. The presentation is directed toward the planning of an open pit copper mine, but the procedures discussed should apply in most cases to any type of metallic or nonmetallic orebody. In planning an open pit mine the pertinent elements that must be included are: assays, geology, tonnage and areal extent of ore reserves, topography, mining equipment, economic factors of operating costs, capital expenditures, profit, types of ore, pit limits, cut-off grade, stripping ratio, rate of production, pit slopes, bench heights, road grades, ore metallurgical characteristics, hydrological conditions, property lines, and marketing considerations. 4.1-2. Sampling. Sampling must be adequate to classify the various materials to be removed from an open pit mine. Drillhole assays are plotted on sections and plan maps with ore and waste blocked out by selected bench intervals. These maps are prepared to depict the geological and other conditions existing on each mine level. The confidence factor to be applied to sampling and the resultant assays values must be given careful consideration. In uniformly disseminated de- posits, the confidence factor will approach unity. For widely fluctuating values, the average assay values should be discounted somewhat, the degree depending upon such factors as drillhole spacing. Such samples, at best, represent a very few pounds for hundreds to thousands of tons of ore

Jan 1, 1968

By G. W. P. Rengstorff

In an effort to find an oxidation-resistant alloy of molybdenum, binary and ternary alloys containing aluminum, chromium, cobalt, iron, nickel, silicon, titanium, tungsten, vanadium, and zirconium were screened. Fourteen other alloying additions were also tested. Many of the alloys were more oxidation-resistant than molybdenum, but none were entirely satisfactory. MOLYBDENUM oxidizes extremely rapidly above 1450°F in air. At 1800°F, a loss of metal at the rate of 0.1 in. in 4 hr is typical. The high speed of this oxidation may be judged by comparison with the oxidation rate of 0.1 in. per year (0.00005 in. in 4 hr), sometimes taken as the maximum permissible oxidation rate at 1800°F for a satisfactory Fe-Cr-Ni alloy. Great strides have been made in the development of coatings and cladding to protect molybdenum from oxidizing atmospheres. These developments in surface protection will undoubtedly make it possible to take advantage of the excellent hot strength of molybdellum and its alloys in many new applications. Still, even the best coating can protect molybdenum only as long as the surface layer is unbroken. Research was undertaken to determine whether an alloy of molybdenum could be found which would resist oxidation. Such an alloy would not deteriorate suddenly when the protective surface layer was destroyed in a small area. In seeking an alloy of molybdenum to resist oxidation, the physical properties of molybdenum could not be sacrificed entirely. The development of an alloy with the desired resistance to oxidation was not achieved. The information obtained on the effect of a large number of elements on the oxidation of molybdenum is, however, of value in the development of coatings. Indeed, many of the alloys tested for oxidation resistance were already known to have poor mechanical properties but were tested to aid in the development of coatings. Oxidation of Molybdenum The rapid oxidation of molybdenum is usually attributed to the volatility of Moo,,. Gulbransen and Wysong have shown that molybdenum oxidizes very slowly up to 850°F, the temperature at which the oxide film begins to evaporate. Melting as well as evaporation of molybdenum oxides promotes the oxidation of molybdenum. MoO melts at 1465°F. MOO, the oxide which is believed to form at the metal-oxide interface, combines with MoO, to form a eutectic having a melting point of 1432°F.' The liquid oxide, even if nonvolatile, could cause poor resistance to oxidation by allowing easy transport of molybdenum and oxygen ions through the oxide. Actually, a sudden increase in the rate of oxidation of molybdenum at 1460°F has been observed to coincide with the appearance of a liquid phase. The formation of a volatile oxide is not unique with molybdenum. The problem is also encountered with vanadium, tungsten, and some of the Pt-Pd group of metals. Vanadium not only forms the volatile V2O3 but, like molybdenum, forms a liquid oxide coating. Few attempts have been made, however, to prevent the rapid oxidation of these metals by alloying. Oxidation of Molybdenum Alloys At the beginning of this work, very little was known of the oxidation resistance of molybdenum alloys. It was known that molybdenum disilicide (with 37 pct Si) has extremely good oxidation resistance,' but this compound is so brittle that it has few uses. It is an effective protective coating for molybdenum when allowance can be made for its brittleness. Chromium was known to retard the oxidation of molybdenum,' but at least 50 pct Cr was necessary to have an appreciable effect. Other, unpublished, reports show that a few other alloys have been given preliminary tests, but the results have not been promising." Choice of Alloys to be Investigated An alloying element might be expected to protect molybdenum in either of two ways: Its oxide might combine with molybdenum oxide to form a stable, nonvolatile complex oxide (a molybdate); or the oxide of the alloying element might form in preference to molybdenum oxide, developing an impervious layer which would prevent the formation of a volatile molybdenum oxide. The knowledge available about the formation of molybdates was meager. Therefore, the initial study was made on alloys of molybdenum with elements having especially stable oxides. On this basis, binary and ternary alloys containing the following six elements were investigated: aluminum, chromium, titanium, zirconium, silicon, and vanadium. Nickel was also added as an alloying element. Although it does not form a more stable oxide than molybdenum, it does impart some oxidation resistance to copper and iron. Its inclusion in the study was fortunate because its alloys proved to be the most promising of those first tested. Apparently nickel formed a stable molybdate. Because nickel was effective in reducing the oxidation rate of molybdenum, the elements iron, cobalt, and tungsten were added to the list. The ten alloying elements mentioned form ten binary and 45 ternary alloying systems with molybdenum. A series of alloys was tested in each of these systems. In addition, at least one test was made on the effect of each of the following alloying elements:

Jan 1, 1957

By A. J. R. Curtis

THE Portland Cement Association was organized more than a third of a century ago by a group of cement manufacturers, to do cooperatively the educational and research work needed to ensure proper use of their product. Specifically, the Association has a threefold purpose: (1) to search out facts to ensure the best possible service from concrete; (2) to give the widest possible circulation to facts affecting the use of concrete; (3) to urge practical application of those facts on actual building projects. An organization of technically trained men conducts many research projects in the Association laboratories, interprets their findings and applies them practically in the field. The net effect of this work has been to improve the design and prolong the life of roads, bridges, industrial, commercial and public buildings, homes, farm structures and concrete products. The results of this technical research and experimentation are made available to the entire construction industry through bulletins and reports. Information is also released to the general public through newspapers, magazines and Association publications. In addition to a1 technical staff in the general office in Chicago, the Association has district offices in 22 cities. Field engineers cover 37 states, the District of Colum-bia and British Columbia, to give service to users of Portland cement.

Jan 1, 1937

By John Sasadi, Karl Heinz Zepter, Leonard Sugin, Roger L. Hulette

Mt. Newman Mining Co. is now completing an expansion program, begun even before initial construction was complete, which will result in the ability to ship up to 35 million tpy of iron ore by early 1973. Located in the Pilbara region of Western Australia, the mine at Mt. Whaleback is about 700 road miles north of Perth and 265 railroad miles south of the port facilities at Port Hedland. Development of the tertiary crushing and screening facilities best illustrates the orderly, but rapid, sequence through which the capacity of the port loading terminal has been expanded. When the present program is completed, crushing and shiploading capability will reach - - 35 million tpy. Operations commenced in 1969 with 3 crusher lines in service; and despite the 5-million annual ton rating, 6.46 million tons of ore were shipped during the first full year of operation. With continuing increase in ore sales, expansion to an annual capacity of 12 million tons was authorized, and installation of two more crusher lines was begun. As a part of this program, provision for installation of a sixth crusher at some future date was included in the planning; but before construction was completed, new ore sales contracts demanded further expansion to an annual rate of 20 million tons, and the sixth crusher line was authorized. The distributing and collecting conveyors had been designed for extension in length and increase in capacity, therefore, conveyor service was provided for the additional crushers with additional belting and hardware only.

Jan 6, 1972

By James P. Kimball

Sulphur is always present in mineral coal of every variety. In the oxidized state it may exist as sulphuric acid in combination with a base. In the unoxidized state it exists in combination with iron as bisulphide of iron. It is also supposed by some chemists to exist in unknown combinations with the organic elements of the coal. This supposition requires the demonstration as a fact that certain coals yield more sulphur than what may exist in a free state, or what belongs to recognized combinations, not only with the accompanying iron but with other inorganic bases abundantly occurring in coals, but which unfortunately are very rarely estimated. This practically as well as theoretically important question it is at present impossible to decide, simply for want of available thorough ultimate coal analyses including the ash. Such analyses, at the best imperfect, are luborious and intricate, and therefore seldom made, the much simpler proximate analyses, so-called, being resorted to by most chemists for technical purposes, and commonly substituted for more scientific work even in the laboratories of government surveys. And it is unfortunate enough that few ultimate analyses are extended to the composition of the ash, much less to its relation to the original constitution of the coal. Sulphur chiefly occurs in most coals in the form of yellow pyrites (pyrite) and white pyrites (marcasite), both minerals, characterized by differences in crystalline form and in physical properties as well as in color, but having the same chemical composition (FeS2). No coal is entirely free from one or both of these dimorphous forms of bisulphide of iron. It may be disseminated through the mass so as to be invisible, in plates or scales between the laminæ of the coal, or in conspicuous segregations or nodules, sometimes of considerable dimensions. Coals greatly differ as to the proportion of sulphur which they contain. They also differ as to the relative proportion in which its several forms of combination occur. Such qualitative and qnantitative disparities arc scarcely, if at all, more marked in separate coal seams of a uniform type than in different parts of one and the same coal seam, whether it be considered locally as constituted of several

Jan 1, 1880

By J. W. Richards

Plating iron with copper has received great attention from practical and scientific men, but, aside from the deposit secured by immersion of iron in copper salts, by electro-plating, or by welding together thin sheets of iron and copper, these efforts have met with no success. Failure of these efforts, in the production of copper plating, has been due to the fact that the conditions normally and necessarily present in the plating operation are antagonistic to the production of copper-plated iron. In most, if not quite all of them, a bath of molten copper has been used. The temperature of a molten copper bath is so high that the iron becomes oxidized before it can be immersed in the molten copper, and unless a protective flux for the molten copper is used, the surface of the copper will become oxidized, and, in any event, the plated iron will oxidize immediately on its being withdrawn from the molten bath. I recently had the pleasure of visiting the works of The Metals Plating Co. at Elizabeth, N. J., where I witnessed the plating of iron sheets with copper by a new process.l The plating metal is applied to the sheet in the form of a liquid mixture by means of rolls, such as inking rolls. The sheet, after being coated with the mixture, is automatically carried forward and deposited on a link-belt conveyor, which carries it through a furnace maintained at a temperature well above that of molten copper. The basic principle involved in this method lies in the application of the plating metal to the sheet while the sheet is cold and then melting the metal in place on the sheet under conditions which are favorable to the formation of the plating. Plating Mixture The liquid plating mixture is composed of either copper oxide or finely divided copper, or a mixture of both, ground to the consistency of a light varnish in a crude oil having an asphaltic base, of a specific gravity of from 14" to 16' Be. The plating mixture which gives the best results

Jan 1, 1919