Search Documents

By T. E. Leontis

Several publications1-7 during the past few years have demonstrated the markedly greater effect of cerium, as compared to all other alloying elements, in enhancing the strength and creep resistance of magnesium at elevated temperature either with or without the presence of other elements. In the work reported in Ref. 1-6, the cerium was added in the form of Mischmetal, which contains all the rare earth elements in essentially the same proportions as they occur in monazite sand, the principal ore of these metals. Mellor and Ridley7 have presented the creep characteristics at 200°C of magnesium alloys prepared both with pure cerium and with Mischmetal. Up to the present time, however, no comprehensive study of the effect of the various component elements of Mischmetal on the properties of sand-cast magnesium has been made. This hiatus in magnesium technology undoubtedly is associated with the difficulty in obtaining the rare earth metals separately. This investigation provides such a survey, the object of which was to determine which of the elements present in Mischmetal contributes the greatest effect in developing high strength and high resistance to creep at elevated temperatures. Toward this end the compositional variation of these properties has been determined as a function of temperature in the following alloy systems: 1. Magnesium-Mischmetal 2. Magnesium-cerium-free Misch- metal 3. Magnesium-didymiuin 4. Magnesium-praseodymium- lanthanum 5. Magnesium-cerium 6. Magnesium-lanthanum This designation, based on the names of the metals as furnished by the producer, is used throughout the paper in order to avoid the complicated system of listing all the elements present in the more complex alloys. The composition of the metals and the alloys is discussed in detail below. Preparation of Alloys ALLOYING INGREDIENTS The chemical composition of each of the six alloying ingredients used to prepare the alloys reported in this paper is given in Table 1. In each case, the percent total rare earths, percent cerium, percent neodymium, percent praseodymium, and percent thorium were determined in addition to the listed impurities. The percent lanthanum was determined by difference from the total rare earth content and consequently includes the other elements (samarium, terbium, yttrium, etc.) present in Mischmetal. These additional elements, however, seldom amount to more than 1 to 2 pet of the total rare earth content of Mischmetal. The iron content of the Mischmetal is considerably lower than that of the other metals. This grade of Mischmetal is now readily available. The metals are listed in the order of decreasing complexity. Elimination of the cerium from Mischmetal results in what the trade calls "Cerium-free Mischmetal." Carrying the separation a step further by eliminating the lantha-

Jan 1, 1950

By H. Kahata, I. Iwasaki, Y. Takahasi

A combined process of segregation roasting-flota-tion or magnetic separation was developed to recover nickel from lateritic iron ores and oxidized nickel ores. An ore was mixed with a halide, such as sodium or calcium chloride, and a solid reductant, and roasted, whereby the nickel content was segregated out as discrete metallic particles. Either by magnetic separation, or by flotation using a sulfhydryl collector together with a heavy metal salt as an activator, the metallic nickel could be concentrated, Effects of such variables as the types and amounts of the halide and solid reductant addition and of the roasting conditions were extensively investigated. The concentration results on several types of ores from Japan, the Philippines, and New Caledonia are presented. Laterite is a residual product of rock decay in tropical and subtropical regions, and consists mainly of hydrated oxides of iron and alumina. Those derived from serpentine sometimes become enriched in nickel, cobalt, and chromium contents. Oxidized nickel ores are of the similar origin, but their nickel as well as silica contents are higher due to gamierite-type silicates. Apparently, nickel enrichment is more pronounced in the transition region between the surface layer of iron laterite and the underlying serpentine. Iron laterites often contain over 50% iron, and their reserve is reported to exceed 22 billion tons, corresponding approximately to 20% of the world iron ore reserve.1 It is readily apparent, therefore, why the iron laterites have attracted much attention of the steel industry as a potential source of iron ores. Numerous attempts to remove nickel and chromium as byproducts, have been reported in literature.' Worldwide discoveries of high-grade iron ore deposits in recent years have inevitably lessened the interests in iron laterites. However, in view of the tremendous potential for their gross value and supplies of nickel, cobalt, chromium, and alumina along with iron, the problem remains as a challenge. Much of the chromium in laterites is present in the form of relatively coarse particles of chromite, and various classification methods have successfully been applied for its removal.2,3 The nickel, however, is intimately associated with limonite, and ordinary concentration techniques are totally ineffective. Much attention has, therefore, been given to hydro-metallurgical or pyrometallurgical means. Yet, all the known processes appear to have limitations either economically or for the use of products as iron raw materials due to a high residual content of nickel. Some attempts have been made to pre-roast laterites or oxidized nickel ores, particularly with sulfidizing agents, and to remove nickel either by magnetic separation,' or by flotation.4 It is apparent that any such concentration process would require grain growth of nickel during roasting for effective separation. Oxidized copper ores are reported to be concentrated by the segregation roasting-flotation process,5 in which the ores are roasted with a chloridizing agent and a carbonaceous reductant in order to promote the growth of metallic copper through repeated cycles of copper chloride volatilization and its reduction on the solid reductant surfaces. Examination of a vapor pressure-temperature diagram of various metal chlorides indicates that a separation of nickel from iron may be effected by a similar process. In fact, the segregation roasting of laterites was reported to increase the extraction of nickel by the ammonia leach process, as compared to the ordinary reduction roasting.6 In the present article some of the preliminary experimental results of the segregation roasting, followed by either flotation or magnetic separation, on laterites and oxidized nickel ores are reported. The effects of various parameters in the roasting as well as in the concentration steps are discussed. MATERIALS AND METHODS An oxidized nickel ore from Thio, New Caledonia, and three laterites from Homonhon, the Philippines, Wakasa and Miyagawa, Japan, were selected for the

Jan 1, 1967

By T. Federighi, S. Ceresara, C. Panseri

The results of an exploratory investigation by means of resistivity measurements at -195ºC, on the aging characteristics of a set of Al-Mg alloys with a maximum content of 7 pct Mg, are reported. Whereas for dilute alloys (Mg < 1.5 pct) only a decrease in resistivity is observed at about 100°C (due to the elimination of quenched-in vacancies), for more concentrated alloys such a decrease is preceded by an increase in resistivity in the range between -60ºand +40°C. Following some previous suggestions, this increase is considered as good evidence for clustering of solute atoms @reprecipi-tation process). From the analysis of the results it appears that, although the process is substantially similar to that observed in other Al-rich alloys, it is characterized by a strong interaction between vacancies and zones. THE process of formation of Guinier-Preston zones, i.e., preprecipitation,1&apos;2 which occurs during the aging at about room temperature in many supersaturated aluminum-rich alloys, has been extensively investigated in the past few years by several workers.2,3 owever, a very interesting question arises when the case of Al-Mg alloys is considered: although it is very easy to supersaturate Al-Mg alloys, just in the same way as for many other aluminum alloys showing preprecipitation, only very little experimental evidence was available until a short time ago in the literature supporting the existence of "natural" aging in supersaturated Al-Mg alloys (see, for example, Refs. 4 to 6). On the other hand, as is well known, the X-ray method is not useful in this case because the X-ray scattering factors of magnesium and aluminum atoms are about the same. Recently, however, Cordier and Detert7 have stressed that during the aging at about room temperature of a supersaturated Al-Mg 10 pct alloy it is possible to detect an increase in resistivity; since, as is well known, such an increase is observed also in most alloys showing preprecipitation, the above authors have interpreted their results as evidence for the formation of magnesium-rich clusters (or Guinier-Preston zones) during the aging. In the course of or ientative investigations on preprecipitation in several aluminum-rich alloys, we also could detect a similar phenomenon in more dilute Al-Mg alloys, see Instituto Sperimentale Metalli Leggeri, Annual Report, 1959, and also Ref. 8. Since the details of our observations, although of a preliminary nature, differ from those of Cordier and Detert and allow one to draw a more advanced picture of the preprecipitation process in Al-Mg alloys, we have thought it useful to report our results in this paper and to comment on them briefly.

Jan 1, 1963

By W. L. Phillips

The plastic properties of lithium fluoride and magnesium oxide under compression were investigated in the temperature range 25° to 1000°C. At the higher test temperatures, the critical resolved shear stress and the rate of work-hardening of both materials decreased. At the same time, the number of stress lines decreased and the individual stress lines became wider. The density of dislocations decreased for a given strain the higher the test temperature for lithium fluoride. The decrease in the critical resolved shear stress as a function of temperature could be fitted by the equation 7 = Toe-KT. THE influence of temperature on the stress-strain curves of a variety of metal single crystals has been studied for a wide range of temperature.1"5 In general, it has been found that both the critical resolved shear stress and the rate of work-hardening decrease rapidly with increasing temperature and fall to a value of essentially zero well before the melting point is reached. AS the test temperature is increased, the density of slip lines has been found to decrease, while the width of the individual lines increases. Recently, Gallagher,&apos; Graf et al.,7 and Pate1 and Alexander8 have found that single crystals of germanium and silicon, which have a covalent bond, can be plastically deformed at elevated temperatures. In compressing germanium it has been found that the strain-hardening coefficient decreased very rapidly as the temperature was increased. The coefficient did not tend to zero, however, as the melting point was approached. The plastic properties of ionic crystals at elevated temperatures have not been extensively investigated. In the only work previously reported Tamman and salge9 and Theile10 have shown that the yield point of sodium chloride single crystals tested in tension and compression decreased slowly with increasing temperature, falling to zero at the melting point. As the temperature was increased, they found a substantial increase in the amount of plastic deformation that could be sustained before fracture; and at temperatures above 400°C in tension tests there was an obvious necking which produced local extensions of up to 3000 pct. The purpose of the present work is to extend the knowledge of high-temperature deformation to the ionic crystals, lithium fluoride and magnesium oxide. The following were investigated: 1) The gross shape of the stress-strain curve at several temperatures. 2) The change in the critical resolved shear stress as a function of temperature. 3) The appearance of slip bands and the density of dislocations as a function of strain and temperature. EXPERIMENTAL TECHNIQUES The lithium fluoride and magnesium oxide used in this investigation were purchased from the Harshaw

Jan 1, 1961

By J. J. Casey, R. S. Busk, D. L. Leman

The mechanical properties and the phase-temperature relationships of magnesium-lithium-aluminum, magnesium-lithium-zinc, and magnesium-lithium-aluminum-zinc alloys are presented. It is shown that the strengths of some of these alloys can be tripled by heat treating and aging but that the high strength is accompanied by brittleness and lack of stability. MAGNESIUM-LITHIUM alloys are interesting because the hexagonal structure of magnesium can be changed into the more ductile and workable body-centered cubic structure by the addition of only 10 pct lithium.1 After Loonam2 determined that the ductility of the magnesium-lithium alloys is destroyed by even trace quantities of sodium, it was possible to prepare ductile alioys and study their mechanical properties. Jackson3 and coworkers have ably described their results with both the binary and polynary magnesium-lithium alloys. The present paper is a report of the mechanical properties of wrought magnesium-lithium-aluminurn, magnesium-lithium-zinc, and magnesium-lithium-aluminum-zinc alloys. Experimental Procedure The alloys were made by melting 7 lb of magnesium in a steel crucible under a molten flux of 75 pct LiCl + 25 pct LiF3 previously dried at 1600°F. The metal was heated to 1300°F for alloying aluminum and zinc and then cooled to 1250°F for adding lithium (sodium content: 0.01 to 0.04 pct). After the lithium had been alloyed, dry LiF powder was sprinkled on the melt to thicken the excess flux. After a 15 min holding period, the flux was skimmed off. Paraffin vapors were used to protect the metal as it was poured into 3 in. diam by 11 in. long magnesium molds. Billets were extruded into 3/8-in. diam rod and 1/16 x 3/4-in. strip; sheet was prepared from 1/8x 7/8-in. extruded strip, first by hot rolling and then by cold rolling 2 pct per pass. Hot rollability, or the temperature range through which the alloys could be rolled, was determined by rolling the strip two passes at 30 pct reduction per pass. Cold rollability, or the percentage of cold reduction to cause detrimental cracking, was determined on 0.064-in. hot-rolled sheet. Standard ASTM procedures were followed to obtain the mechanical properties, using 0.2 pct offset for the yield strengths. The level of properties produced with commercial magnesium alloys using the procedure described is given in a previous publication." Results Magnesium - Lithium - Aluminum System: The good workability of magnesium-lithium alloys is illustrated by the data in table I, which shows approximately how the extrusion pressure decreases as the amount of cubic phase increases. Binary magnesium-lithium alloys are soft and weak, but aluminum raises their strengths con-

Jan 1, 1951

By Y. Jeannin, C. Mannerskantz, F. D. Richardson

Measurements have been made between 1040o and 1300°C of the equilibrium between chromium metal, chromic oxide, hydrogen, and water. The results are in closer agreement with those deduced from recent thermal data than with previous equilibrium values. They lead to the equation ?G°1300°-1600°k = -266,700 + 59.95T ± 300 cal for the formzation of a mole of Cr2O3 from chromium and oxygen. This same equilibrium has been studied with the chromium dissolved in solid iron, and in this way chromium activities in Fe + Cr alloys have been established. The measuremenis show that there are substantial positive deviations from ideality in the a, and b phases, and support the results obtained by Heymer and Kubaschewski against those of other investigators. There is considerable disagreement between existing data,1"4 which is referred to in the Discussion, concerning the equilibrium Cr2O3 + 3H2 = 2Cr + 3H2O [l] There is also substantial disagreement between the results obtained by various investigators5-&apos; who have measured the activities of chromium in its alloys with iron by the Knudsen effusion vapor pressure method. In view of the importance in metallurgical processes of chromium and its oxide and of Fe-Cr alloys, an attempt has been made to study equilib- rium [I] both with pure chormium metal and with chromium alloyed with iron, at temperatures between 1040o and 1300oC. From the work with the alloys it is possible to derive the chromium activities from the relationship

Jan 1, 1963

By J. L. Huitt, D. K. Lowe

This laboratory flow study covers propping agent transporl in horizontal fractures as influenced by the characteristics of the propping particles, fluid and fracture. Correlations are presented for the transport of particles, deposition and fingering through dunes. For particles moving individually, the article velocity in some cases may be low compared to the hulk average fluid velocity; in other cases, the particle velocity may exceed the bulk average fluid velocity. At high propping agent concentration or low fluid velocity, the likelihood of particle deposition and dune formation increases. Fingering and channeling accompany dune formation. Dune formation can be limited to the outer region of tile fracture by adjustment of pump rate, fluid viscosity and particle concentration. A method is presented by which pump rate and fluid vircosity may he selected to control dune formation for given propping agent concentrations. INTRODUCTION The area and flow capacity of a fracture predominantly control the stimulation derived from hydraulic fracturing. Generation of fracture area exposes the rock matrix to a flow channel; the flow capacity of the fracture controls the flow through the channel to the wellbore under a given pressure gradient. This paper pertains to an important factor that affects the flow capacity of a fracture: the transport of the propping particles in the fracturing during the hydraulic fracturing treatment. With a better understanding of particle transport, fracturing treatments may be designed to obtain more effective distribution of the propping agent. RELATED STUDIES In recent years, the approach to obtaining high fracture flow capacity has been partial monolayer propping. Three papers1-3 have dealt with various facets of this concept. However, in some papers dealing specifically with particle transport, the results generally indicate that packing the propping particles within a fracture is inevitable. In early work&apos; with a sand slurry flowing in a pie-shaped flow cell, qualitative results showed that particle deposition in a fracture during transport should be expected. In other studies"" correlations based on slurry flow in vertical linear flow cells showed particle deposition was primarily a function of fluid velocity. In a recent paper the rate of sand advance (movement of dunes) in a horizontal linear flow cell was discussed. Subsequently, a method was given for designing fracturing treatments, based on the extent of sand advance during a treatment. In this work, particles whose diameter was small relative to the fracture width (i.e., dl W< 0.2) were primarily considered. The particle transport approaches that of sand transport in a stream bed. The industry trend, however, has been to use larger size propping agents. That is, particles with diameters approaching fracture widths predicted by Perkins and Kern.&apos;&apos; This trend has led to generally better fracturing treatments with particle relative sizes in the range 0.2 <d/W < 1.0. In all of the particle transport studies previously cited, the fluid characteristics were discussed. However, little or no attention was given to the parzicle characteristics. In this study the particles. as well as the fluid and fracture, are considered. VARIABLES AFFECTING PARTICLE TRANSPORT In the exploratory work to set LIP a program for this study, it was noted that particles within a batch moved at different velocities in a horizontal linear flow cell. In some cases the particles moved independently. In others there was particle interference. Also, particle deposition and fluid fingering occurred in some cases (Fig. 1). As a result of observing the easily distinguishab&apos;le types of particle movement, the particle variables as well as the fluid variables were included. In addition, the fracture width was included because the fluid velocity profile surely must affect the movement of the larger particles differently than that of smaller particles. Particle variables were density, diameter (based on a sphere of equal volumetric displacement), long and short dimensions, drag coefficient and velocity. Fluid variables were density, viscosity, yield shear strength and velocity. Fracture variables were the width and the angle between the plane of flow and a horizontal plane. Two factors which may prove to be important were omitted because of the complexity resulting from the parameters cited above. These are the fracture-surface roughness and gross irregularities that cause changes in the direction of flow. EXPERIMENTAL EQUIPMENT AND PROCEDURE A linear parallel-plate flow cell (Fig. 2) was used in the study. Lucite plates 1 in. thick formed the test section and permitted a viewing section 11 ft long and 10 in. wide. Spacing between the plates was adjusted with shims to give fracture widths 1/36 to 1/2 in. The model could be tilted to an angle of 45" with the horizonltal plane. Fluid flow was maintained with a Moyno positive displacement pump. Single particles were placed in the flow stream with a particle injector. A .4 - in. diameter plunger moving at a constant rate in a

Jan 1, 1967

By J. J. Demo

The effect of aluminum additions on the coating vale and corrosion resistance of Cr-Fe diffusiou coalings on a mild steel substvate has been studied. Aluminum additions up to 2 wt pct increase the chromium penetration rate while further additions retard it. The apparent cor$lict between these data and metallogyapkic ineasurements, which show a continuially increasing coaling thickness with aluminum addition, is discrissed. Compavisorz of corrosion resistance on the basis of equal thickness of tlre entire coating measured mnetal- ALTHOUGH ferrous metal articles are cheap and widely used, they are often quickly degraded by corrosion. To prevent or slow down the corrosion process, lographically is misleading; equal thickness of the cor-rosion-resistant portion of the coating is a bette.v basis of conzpavison. Inter difision coefFicients for Cr-Al-Fe coatings of different aluminum content have been detevmined and found to dary logarithmically when plotted againnst chromium concentvation. A general method of calculating diffusion profiles for different lrealment limes and surfuce coucentralions IS described. many types of coating are applied to steel.&apos; Among these are diffusion coatings, formed by high-temperature diffusion of selected elements into the surface, which then becomes the coating Diffusion coatings are metallurgically bonded to the substrate and show a continuously varying concentration gradient from surface to substrate. Generally, these coatings have the advantage of adhering to the substrate upon deformation of the composite. Moreover, when chromium is one of the diffusion elements, a mild steel substrate

Jan 1, 1968

By Frank Fahrenwald

I. INTRODUCTORY METALLURGICAL research has discovered many an alloy possessing properties not combined in any single metal, and progress still consists chiefly in the investigation and utilization of alloys. In the case of iron, the demands of automobiles, high-speed machines and high-duty engines have led to the production of special iron alloys which will meet any reasonable specifications in that field. In like manner, the bronzes, brasses and other alloys of copper have been brought to remarkable perfection, and for nearly every industrial purpose some alloy has been found more suitable than the pure metal. Less complete success has attended the attempt to find substitutes for gold, platinum, and the other precious metals. Indeed, it is not likely that a material can be produced which will possess all the properties of any one of them; yet it is reasonable to hope that, for any given use, the properties required may, be found in some less expensive material. Thus, in incandescent electric lamps, the wire passing through the thick glass neck of the bulb was, until recently, almost universally made of platinum, for the single reason that no other known material, suitable as a conductor, had the same coefficient of expansion as glass. But a comparatively recent investigation of the iron-nickel series&apos; has shown that alloys of those metals may be produced, the coefficient of expansion of which can be accurately controlled between that of iron or nickel and zero. Thus, in that particular industry, a substitute for platinum has been found. According to statistical reports, not only considerable quantities of gold and iridium, but also more than one-third of the annual supply of platinum, are used (and, in the nature of the case, irrevocably lost) by dentists. Platinum is thus employed in several forms. As a thin foil, it serves various purposes for which its high melting point, pliability, chemical resistance, and other properties-including the ease with which

Jan 1, 1916

By W. D. Robertson, H. Conrad

Incremental loading creep tests were conducted on magnesium single crystals in tension and direct shear at 78" to 364°K. The creep curves were transient in character and exhibited waves or periodic behavior, especially at small strain rates. A sigmoidal curve was frequently observed following the first occurrence of creep. Repeating of segments of a master curve was observed at all temperatures indicating that identical conditions for flow existed after various stress and strain histories. A logarithmic time law with a independent of temperature whs observed at 78°and 203°K, while a parabolic (power) time law was approximated at 298" and 364°K. The departure from logarithmic creep was attributed. to recovery, which was observed at 298" and 364°K. The temperature independence of a represents a serious objection to the theory of low-temperature creep based on the intersection of dislocations. IN a previous paper1 it was found that the initial creep rate of magnesium single crystals, y, following the addition of a stress increment in the range of 78° to 364°K, was given by the expression ? = C exp - {?H/kT} exp {B(T- h ?)} [1] where B and C are constants, AH is an activation energy of 10,300 cal per mole, T is the applied stress, ? is the total strain at the time of the stress increment, and h is the strain-hardening coefficient. The present paper is concerned with certain other features of creep behavior observed during this investigation; namely, the form of the creep curves, time laws for creep, recovery, and microscopic and X-ray observations of the structural manifestations of the creep flow. To the authors&apos; knowledge the temperature range of the present investigation (0.08 Tm to 0.40 Tm) has not been covered previ-

Jan 1, 1959

By P. H. Brace, N. A. Ziegler

The study of the relations between gases and metals is one of pcren-nial interest to all who are connected with the production of high-grade metallurgical products. The data reported here are the outcome of work of which the object is to determine the effects of dissolved gases upon the properties of metals and to gain a more detailed knowledge of the reactions between gases and molten metals, particularly iron, under definitely controlled conditions. We have attempted to reduce our margin of error by dealing with relatively large quantities of metal, from 4 to 13 Ih. (2 to 6 kg.), and keeping the ratio of refractories to metal as small as practicable. The ingots produced are large enough to provide adequate material for making determinations of magnetic and other physical properties. In choosing the bell-jar type of furnace we were influenced by the results of considerable experimentation along the same general line which indicated that, for the scale on which we were to work, it was important to have the furnace structure independent of the vacuum enclosure. The use of a bell-jar surrounding the entire furnace accomplishes this and also gives great freedom of observation during operation and ready accessibility for the replacements which are necessary after each run. Our choice of analytical method was made in the light of the results secured by H. M. Ryder, who used a method similar in principle for the analysis of very small quantities of gas extracted from strips of metal heated electrically in high vacuum. We have presented some selected preliminary experirnental data as being illustrative of the quantity and nature of the gases which occur in iron of different origins, but do not urgc any hypothesis at this time. The Furnace Our furnace may be described as "a high-frequency induction furnacc of the bell-jar type." It is similar in a general way to that described by Cain and Peterson1 though we have introduced certain refinements of

By G. Koves

The behavior of case-hardened AISI C-1213 free -machining steel under complex impact-fatigue -wear load conditions was investigated. The inherently poor dynamic properties of the steel are mainly affected by the stress distribution in the case, component shape, and tempering. Cold-riveted components showed unexpectedly high dynamic strength compared to basic parts. A compromise beatment—which provides good dynamic properties, reasonable wear resistance, and fair riveting characteristics—zuas developed. A number of mechanical components in data-processing machines are made of free-machining carbon steel. Although, selected primarily due to manufacturing requirements, components made of these grades frequently undergo complex heat treatment and must sustain impact-fatigue loads. A typical free-machining steel is the AISI C-1213 grade, which is a resulfurized and rephosphorized open-hearth steel. While the undesirable effects of sulfur and phosphorus on the mechanical properties are well-known, data on dynamic properties are scarce.1"3 Rapid rotating or oscillating motion while carry- ing a high cyclic load requires a combination of wear resistance with high endurance limit and impact toughness. The inherently poor dynamic properties of the free-machining steel are further degraded by the machining, which introduces local stress-concentration areas. While the heat treatment (usually case hardening) improves some mechanical properties, it necessarily impairs others. Another problem arises when components, such as studs, must be fastened by riveting. The high crack-sensitivity of the free-machining steel, especially in the presence of a hardened case, makes this operation difficult. In view of the preceding considerations, it is of interest to investigate the behavior of a typical component under complex impact-fatigue-wear loading conditions in order to explore the effects of material, machining, and heat treatment, to obtain specific data on the dynamic characteristics of free-machining steel, and to arrive at a process which would adequately utilize the inherent qualities of this material. EXPERIMENTAL PROCEDURE To simulate actual service conditions, a typical component was selected, based on frequency of application, complexity of load, and processing difficulties. The dimensions and shape of the component—a stud used in many electromechanical document-handling machines—are shown in Fig. 1.

Jan 1, 1964

By W. R. Crane

The effect of mining in the red-ore mines of the Birmingham district has been observed for some time, but, except in a few localities, little difficulty has been experienced from disturbance of cover. Cave-ins near the outcrop and fracturing of the surface at greater distances are the most pronounced manifestations of disturbance, while limited areas at points distant from the outcrop and under greater depth of cover have actually subsided. were it not that the orebed is overlain by one or more water-bearing formations, the fracturing or settlement of the surface would not be serious; but because of these formations, fracturing of the top rock may in itself be of sufficient importance to warrant the adoption of protective measures. Further, the collapse of pillars over a wide area may develop squeezes that, if not controlled, may jeopardize the integrity of the mines and necessitate a change in development, from slopes to vertical shafts, at a much earlier period than is now contemplated. Drainsge in these mines has been discussed in papers on mining practice,&apos; but the fact that water, varying from 0.16 to 3.46 and averaging 1.43 times the amount of ore mined, has to be pumped from the mines daily, indicates the importance of the problem and the advisability of making a thorough investigation of the source of mine water, its mode of entry into the mines, its effect upon mining conditions, and consideration of means of improving the conditions.

Jan 1, 1927

Research and Development, once considered a luxury item only for well-heeled companies, has in the last two decades come into its own as a vital contributor to the fortunes of electronic, automotive, chemical and aerospace firms. In terms of money and talent poured into research, the mining industry is still far behind those industries. Although the U.S. Bureau of Mines, plus various mining and manufacturing firms and universities have made notable contributions to mining technology, the historical pattern of mining R&D shows a heavy reliance on the results of research in other industries. It is difficult to tell whether this pattern will change significantly in the future, but there is evidence of a growing awareness by mining officials that greater R&D efforts are going to be required not only to meet the nebulous demands of tomorrow&apos;s world but to meet the ever-present, mounting pressures being generated by "intra-metals" and "inter-materials" competition.

Jan 1, 1968

By R. J. Wagner, G. H. Gronhovd, A. J. Wittmier

The paper describes the results of a series of full-scale boiler tests run to determine the ash fouling characteristics of a North Dakota lignite as a function of sodium content of the coal. Four levels of sodium were investigated and rate of fouling was determined both by boiler performance and by specially constructed probe equipment. Discussed is information on chemical and physical properties of the ash deposits. The vast lignite deposits in North Dakota are becoming increasingly important as a source of low-cost fuel for power generation. A new 200-megawatt lignite-burning plant located near Stanton, N.D., was placed in operation early in 1966. Another 172-mega-watt unit in the same area is scheduled for operation late in 1966, and plans have recently been announced for a 212-megawatt unit to be in operation by 1970. If these plants show good performance, western North Dakota could become a major power production center for a large geographic area in the upper midwest. One of the problems associated with the use of lignite in power boilers is its tendency to form troublesome ash deposits on boiler tube surfaces. This problem varies considerably from one lignite-fired boiler to another and is dependent upon such factors as source of lignite, boiler design, load factor, tube metal temperatures, and soot-blowing practices. This report presents data on sodium content* variation in a North Dakota mine, describes the results of a series of tests performed to determine the relationship between ash fouling tendencies and the sodium content, and tells how the mining company and electric utility have coordinated their operations to reduce the ash fouling problem. GENERAL BACKGROUND Until recent years it was generally assumed that North Dakota lignite from a given mine had qualities peculiar to that mine, but that within the mine, the lignite was quite uniform. In 1959, the Otter Tail Power Co. installed a 53.5-megawatt lignite-burning unit at its Hoot Lake plant, Fergus Falls, Minn. Shortly after the unit was put into operation, it was noted that at certain times under high load conditions, ash fouling problems were quite severe, but not consistent or predictable. Each time fouling occurred in the unit the position of the loading shovel at the mine was noted. Within two years it became apparent that there were certain areas in the Knife River Coal Mining Co. mine at Beulah, N.D., where the lignite apparently had a high fouling tendency for the Hoot Lake unit. Results from analyses of the coal did not show large differences in moisture percentage, ash percentage, heating value, or ash fusion temperature between the highly troublesome and less troublesome coals. After three years of operation, the troublesome areas had been quite well defined and the mining company started a procedure of bypassing these areas when load conditions at the plant were high and then returning to the troublesome areas to load the lignite during the summer months when peak loads were lower. It was noted that the lignite from the areas which caused severe fouling under high load conditions produced much less fouling at the lower summer loads. However, bypassing certain areas in the strip pit caused the mining company to disrupt their continuous loading schedule, which in turn upset their continuous stripping schedule and made for less efficient mining operation. Meanwhile, at the Hoot Lake plant, the number of soot blowers on No. 2 boiler had been increased from 30 to 55, and a very rigorous blowing schedule had been adopted resulting in soot blowers operating at least some part of 21 hrs per day. Fouling problems continued, with a resulting reduction in plant economy and reliability. During this period the Federal Bureau of Mines Coal Research Laboratory at Grand Forks, N.D., had initiated various research programs relating to the study of lignite ash and ash fouling problems. One project was a survey in which full seam samples were obtained from various locations in all the major

Jan 1, 1968

By Thomas Cox

The following compilations are made from a series of investigations and are used to present the subject in an unbiased manner, as the writer does not represent any company or financial interest. The present situation is complex. The producers are hard pressed by reason of the low price of crude, while the independent refiner is little better off, because of the corresponding cut in price of refined products, except on occasional contracts. If the real costs are analyzed, it will be seen that the land speculators and the lessors—royalty owners—make the larger profits and not the struggling legitimate operator or independent refiner. The present-day (October, 1922) posted prices per barrel for crudes are Kansas, Oklahoma, Mexia, Gulf Coast, and Louisiana..... $1.25 Healdton............................................. 0.75 Northern Texas and Central Texas...................... 1 . 50 Pennsylvania......................................... 3.00 Wyoming, Elk Basin.................................. 1.25 Wyoming, Salt Creek................................ 0.70 California Base..................................... 0.60 These prices are at the well. In addition, crudes must be gathered and transported to refinery (by pipe line or tank cars), refined, and the refined products marketed. These crudes are of various gravities, ranging within a narrow margin for each field or district, so that averages are not difficult to deduce, and it is these averages that really determine the average operating conditions. In order to show the present realizations, the prices and costs now obtaining are listed against the average yields; the figures are also adjusted VOL. urn.----71

Jan 1, 1923

By Thomas Cox

The following compilations are made from a series of investigations and are used to present the subject in an unbiased manner, as the writer does not represent any company or financial interest. The present situation is complex. The producers are hard pressed by reason of the low price of crude, while the independent refiner is little better off, because of the corresponding cut in price of refined products, except on occasional contracts. If the real costs are analyzed, it will be seen that the land speculators and the lessors—royalty owners—make the larger profits and not the struggling legitimate operator or independent refiner. The present-day (October, 1922) posted prices per barrel for crudes are Kansas, Oklahoma, Mexia, Gulf Coast, and Louisiana..... $1.25 Healdton............................................. 0.75 Northern Texas and Central Texas...................... 1 . 50 Pennsylvania......................................... 3.00 Wyoming, Elk Basin.................................. 1.25 Wyoming, Salt Creek................................ 0.70 California Base..................................... 0.60 These prices are at the well. In addition, crudes must be gathered and transported to refinery (by pipe line or tank cars), refined, and the refined products marketed. These crudes are of various gravities, ranging within a narrow margin for each field or district, so that averages are not difficult to deduce, and it is these averages that really determine the average operating conditions. In order to show the present realizations, the prices and costs now obtaining are listed against the average yields; the figures are also adjusted VOL. urn.----71

Jan 1, 1923

By Cyril Stanley Smith

Jan 1, 1949

By Cyril Stanley Smith

Jan 1, 1949

By F. W. Lake

The ultimate production from a natural reservoir of petroleum is inversely proportional to the gas-oil ratios existing during the producing life of the reservoir whenever gas is the major expulsive force in the recovery. In other words, in the period during which gas is the major expulsive force the ultimate production will be increased if the gas-oil ratio is decreased, and vice versa. This condition prevails in the greater number of the present producing districts. While this relation is difficult to prove from actual operation, on account of the present paucity of detailed observations, it must be admitted after a study of the forces and conditions governing the recovery of petroleum from natural reservoirs. Where gas and oil exist under pressure in sand interstices and water movement is not freely possible, the force expended in moving the oil to the well is the expansion and movement of the gas through the pressure differential existing between the interior of the reservoir and the well. If pressure and solution conditions in the untapped reservoir are such that the relation between gas and oil volumes at atmospheric conditions is as 100:1; and if during the producing period, until the gas is exhausted, the relation between the gas and oil volumes produced is 300:1, it follows that only one-third of the oil has been produced and the remaining two-thirds cannot be recovered unless some extraneous force is introduced into the reservoir. This serves to illustrate the importance of gas-oil ratio control during normal producing operations. Gas-oil Ratio Control Eliminating natural conditions in a reservoir, which govern gas-oil ratios, such as the physical properties of the oil and gas, the physical characteristics of the reservoir strata and the original pressure and solution conditions in the reservoir, which cannot be controlled by operation practice; and also eliminating operating conditions that apply to the reservoir as a whole, such as well spacing, well locations, relative completion dates, various penetrations and drilling practice; there remains but one condition in each well that influences the gas-oil ratio and that is

Jan 1, 1928