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Jan 1, 1966

Jan 1, 1937

By Clarence Zener

[ ] THE present investigation started in an attempt to understand certain details of the decomposition of austenite, and of the effect of alloying elements thereon. As the investigation proceeded it became apparent that not only these details, but all the general features of austenite decomposition, could be understood in terms of fundamental physical principles. Since the direct applicability of these physical principles has not been previously recognized, it was decided to incorporate the original results of the investigation into a review of the general subject of the kinetics of austenite decomposition. This review constitutes the present article. An extended summary of the results is given on pages 27 to 30. This article, which deals with the kinetics of phase transformations, may appropriately be considered as a sequel to two recent articles1,2 from this laboratory on the equilibrium relations in medium alloy steels.

Jan 1, 1946

By Ray W. Amstutz

The shaft was drilled on US government land m the Piceance Creek basin and was funded by the US Bureau of Mines (USBM). It was drilled to 723 m to provide access to rich deposits of oil shale, nahcolite, and dawsonite for geotechnical test work and environmental mining research. Rotary drilling and dual-string, reverse-air, jet-assist circulation methods were used. Drilling required eight months. Site preparation, running, and cementing the casing required another four months. A 2.44-m ID steel welded casing, 508 mm thick was installed and 2.7 kt of cement were slurried and pumped into the annulus.

Jan 1, 1982

The Mineral Industry, Published by McGraw-Hill Book Co, New York, N Y. The Mineral Industry is an annual review of the mineral industry It is a standard and complete reference on the mineral industry for the year covered Through the cooperation of the A I M E its publication in 1933 was made possible Mineral Industry for 1930 contains sections devoted to the production, consumption, trade, market, uses and technology of the following headings: Abrasives, aluminum and bauxite, antimony, arsenic, asbestos (b), asphalt, barium and strontium, chromium (b), coal and coke, cobalt (b), copper, diatomite, fluorspar, gold and silver, graphite, gypsum, iron and steel (b), lead, magnesite, manganese, mica, molybdenum, nickel, petroleum and petroleum products, phosphate rock (b), platinum group metals (b), potash, precious and semiprecious stones (b), quicksilver, radium (b), uranium and vanadium, slate (b), sodium salts, sulfur, pyrite, sulfuric acid, talc and soapstone, tin, titanium and zirconium, tungsten (b), zinc, minor metals, minor nonmetals, ore dressing and coal washing (b). Sections marked (b) have appended a bibliography of recent literature on the subject. Each section is written by an acknowledged expert. Other volumes contain similar material Prices -The Mineral Industry, 1892-1930, vols. 1 to 39. Complete sets of this work, uniformly bound, except vols 25 and 26,

Jan 1, 1933

By Kenneth J. Kurry

12.2-1. Introduction. Successful management constantly strives to improve its methods and equipment in order to produce a better product at reduced cost. It is not enough that managers be cost conscious and industrious in these days of rapid, dramatic technological development. They must keep abreast of these developments-new or improved methods, machines, and equipment. Most of the machines and equipment have been carefully designed and perfected by reliable companies. However, improvements and progress often evolve from a definite need and are most successful in a particular operation. What may be the "answer" to the requirements of one company may be totally useless or inefficient to those of another. The manager of today must continuously evaluate the myriad proposals for change that result from modern technology-in terms of the particular needs and objectives of his company-to determine correctly which will best satisfy those needs and reach those objectives. Each new method or piece of equipment must receive careful study to make certain it is compatible with the entire operation. It may solve a problem in one department only to create a new problem in another. There are many pitfalls to be avoided in obtaining the necessary facts, and often these problems are unrelated to the actual use of the equipment or method being studied. All facets of the operation being considered must be thoroughly studied to determine if the method is compatible to the entire operation. For example, in considering a possible recommendation that a certain method and type of equipment be used to transport ore, some of the factors that should receive close scrutiny are: blasting procedure, maintenance, turning radius, percent grades, weather extremes, dumping problems, tire problems, length of haul, operator acceptance, or mismatched equipment. Failure to consider every factor-large and small, present and future-in evaluating a proposed change can mean a large investment in a new method or machine that will have to be continued for years at higher-than-antici-

Jan 1, 1968

Here are the details . . . . . of how a $2.5 million research gamble, now backed by five years of intensive development in cooperation with the Chemical Construction Corp. resulted in a hydrometollurgical process that yields pure metal powders from sulphide concentrate - a process that offers potential savings of $2.5 million a year.

Jan 6, 1953

By Clarence A. Seyler

The object of all classification is to group together things which are alike, and separate those which are unlike. This object is essentially a practical one, enabling us to apply past experience to new conditions. Many costly large-scale experiments lose half their importance for want of proper description of the coal used, and the consequent impossibility of predicting that other coals will behave in the same way. I do not, therefore, make a fundamental distinction between "scientific'' and "use" classifications, except in so far as use depends on conditions, such as size or impurities which are not related to the nature of the coal substance itself. The characters chosen to define the classes of coal must be such as are accompanied by as many other properties as possible. It is not to be expected that any system of classification will enable us to predict every property of coal, since all specimens have an individuality of their own. But specimens can be grouped by a number of resemblances into species. Further, species which resemble each other can be grouped into genera. Elementary Composition as a Basis of Classification There can be little doubt that the ultimate or elementary composition of "pure coal" is the best basis of classification. It was soon after the perfection of the method of elementary analysis of organic substances by Liebig that Regnault, the distinguished chemist and physicist, laid down the principle that coals of the same kind vary only between narrow limits of elementary composition. This is still the widest generalization that can be made about coal. Upon it the metallurgist Gruner based his classification. In some quarters the value of the ultimate composition was denied, Stein going so far as to say that it teaches us nothing of importance about coal. One still hears statements that it is like crushing a work of art in a mortar and analyzing the powder, or like counting the number of times a given letter occurs in a sentence. Such comparisons are misleading, and the criticism might be applied to organic chemistry as a whole. Nor is the existence of isomerism, or of entirely different substances which

Jan 1, 1928

By J. Ostachowicz, B. Holynska, M. Lankosz

The paper presents an analyzer and the method for the continuous determination of weight percentage of ore grains with diameter smaller than 75 µm in mineral slurries. The method is based upon the measurement of characteristic x-rays of copper excited by primary radiation of two different energies 16.5 keV and 60 keV from Pu238 and Am241 sources respectively. Additionally the backscattered primary radiation is measured in order to correct the variations of the solids content in the slurry. Since the particle size distribution of slurry can be described by the Rosin-Rammler formula, some calculations have been carried out in order to evaluate the influence of distribution parameters upon the results of the measurements of weight percentage U75 of particles smaller than 75 µm. The influence of solids content and of the copper concentration variation on the results has been also evaluated.1 It resulted from the calculations that the ratio rl/rz, where rl and r2 are the relative intensities of copper characteristic x-rays excited with 16.5 keV and 60 keV photons respectively does not depend on the copper content within the range 1 % to 4% of copper and is slightly dependent on the solids weight fraction and its chemical composition. The change of the dispersion parameter of the Rosin- Rammler distribution from 0.5 to 0.9 results in a change of value of U75 of approximately 3.0%. The results of calculations have been confirmed by the results of laboratory experiments. Therefore, a prototype of industrial analyzer for continuous determination of weight percentage of particles smaller than 75 µm has been designed and made. Its schematic drawing is shown in [Fig. 1]. Slurry is flowing down through steel flow-cell of the length equal to approx. 2 m. In the center, two XRF measuring heads (1) and (2) are located. Each of the heads comprises a rigid waterproof cover (3) with the mylar window (4), in which a proportional counter of resolution 15% for 6.4 keV is mounted with a preamplifier (5). The low- energy isotope source (6) is centrally located above the detector

Jan 1, 1980

For the benefit of those of our members who are considerable holders of securities, but owing to their isolated situations are not in close touch with the metropolitan market and current quotations, we are publishing two very interesting graphs, showing the course of the bond and stock markets in New York over a long period. These graphs are furnished through the courtesy of the financial department of the New York Tribune.

Jan 12, 1919

FOR the benefit of those of our members who may be asked what they know about Mr. Hoover's connec-tion with the Kaiping coal mines in China and who will naturally wish to appear thoroughly well informed on the subject, we reprint below an authoritative state-ment, recently made to the Japan Advertiser, by Tang Shao-yi, former premier of China, now retired to his country home at Tang Chia. "Information has reached me at my retreat that persons in America and China insinuate that Herbert Hoover acted dishonorably in dealings involving the Chinese Engineering and Mining Company a quarter of a century ago. I be-lieve myself the only Chinese living who was closely iden-tified with that company during Mr. Hoover's connection. My uncle founded the company and my family always has been a large shareholder and, therefore, I possess direct knowledge of its history. "I am actuated in this statement by a sense of justice and also gratitude for Mr. Hoover's acts in rescuing my family during the Boxer uprising. Mr. Hoover's record in China is clean and honorable, highly creditable and in many ways remarkable. Legal action brought in London in 1905 occurred after Mr. Hoover left the company. There were not any charges against Mr. Hoover and he was not a de-fendant in the lawsuit, but an important witness whose testimony helped the Chinese shareholders to save their property.

Jan 5, 1928

By Edmund Shaw

In the year just past there were produced in the United States about 170,000,000 tons of sand and gravel. Much of this was pit-run material used for gravelling roads and as railroad ballast on lines that did not carry heavy traffic. But more than half of it was marketed as washed and sized, or graded, material. The methods used for preparing sand and gravel for the market have long been used in ore dressing and, as in ore dressing, depend on differences in the specific gravity of two substances or in the size or weight of particles. But many changes in the design and operation of plants and machines have been necessary. In ore dressing, the concentrate is only a small part of the feed; in sand and gravel washing, it is much the larger part of the feed. In addition, such close work as is needed when concentrating a metallic ore is not needed when washing gravel; the ability to put through a large tonnage is more important, and sizing, which is only a preliminary process in ore dressing, is an end to be attained. Rock crushers are found in most sand and gravel plants and they are used to break up the larger pieces from the deposit (known as boulders and cobbles) which are removed by a scalping screen. The crusher discharge is usually sent back to the scalping screen, the perforations in this screen setting the maximum size of the finished product. Washing Washing is to prepare sand and gravel so that they may be used as aggregates in concrete and wall plaster and in various processes in which impurities would harm the product. At one end of the scale of washed materials may stand ordinary concrete sand, which in some states may contain as much as 3 per cent, of clay and still be used in highway concrete construction. At the other end will stand the silica sand used for making plate glass, which must be washed so clean that the impurities that can be removed by washing do not exceed a few hundredths of a per cent. The methods and machinery that would produce one of these

Jan 1, 1926

Jan 1, 1968

By R. Ellerman

The hydrometallurgical processing of an impure zinc oxide fume is described. Flowsheet includes roasting for fluorine elimination and countercurrent leaching to produce a neutral sulphate solution. This solution is combined with zinc sulphide leach solution for subsequent purification and electrolysis. Novel to the neutral leach step is the use of automatic pH control. THE electrolytic zinc plant of the Hudson Bay Mining and Smelting Co. Ltd. was erected in 1929-1930 to process zinc sulphide concentrates produced from ore mined at Flin Flon, Manitoba. Since 1930, production of high purity slab zinc has been continuous. In May 1951, construction of a fuming plant was completed and operations were started to recover zinc from copper smelter reverberatory slag. A second zinc-bearing material in the form of an impure zinc oxide fume was then made available for treatment. Coincident with the construction of the fuming plant, additions were made to the electrolytic zinc plant to recover the zinc in the fume as slab metal. The original plant capacity of 70 tons of slab zinc per day was steadily increased up to May 1951, at which time the daily production averaged 130 tons. With the advent of the fuming plant and the processing of zinc oxide fume, production was stepped up to the present capacity of 190 tons per day. Of this, approximately 48 pct is contributed by the processing of zinc oxide fume. This additional source of raw material has allowed a 20 pct cutback in mining and milling operations, thereby adding considerably to the life of the Flin Flon mine. Zinc sulphide concentrates are treated by the usual hydrometallurgical method. Details of this operation and plant were described by Carr and Reikie in 1935' and Kent in 1951.8 The impure fume is treated in two operations. First, it is roasted to eliminate fluorine. Next, it is subjected to a countercurrent leach with spent electrolyte to extract the zinc as a neutral zinc sulphate solution. During this leaching step, soluble impur-

Jan 1, 1956

By E. A. Steigerwald, G. L. Hanna

The influence of work-hardening exponent on the variation of fracture toughness with material thickness was studied for high-strength steel, aluminum, and titanium alloys. The results indicate that, when materials are compared at similar fracture toughness to yield strength ratios, the material with the lower work-hardening exponent undergoes the transition from flat to slant fracture at a larger thickness than material with a high work-hardening exponent. In the thickness range where complete slant fracture is obtained the reverse is true and a lower work-hardening exponent results in a lower fracture toughness. The influence of work-hardening exponent on fracture toughness is, therefore, dependent on the particular fracture mode. In the transition region a low work-hardening exponent is beneficial for fracture toughness while in the 100 pct slant region it is detrimental. THROUGH the use of fracture mechanics analyses, the influence of geometric variables on the crack propagation resistance of structures can be interpreted with reasonable consistency. However, in order to gain a more complete understanding of the fracture process, the influence of material parameters on crack propagation must be defined and coupled to the macroscopic fracture mechanics approach. The work-hardening exponent, which characterizes specific material behavior, may serve as an effective parameter to allow some degree of coupling to be accomplished. In the extension of a crack in a specimen of suitable dimensions the propagation process occurs in a stable manner when the crack extension force is balanced by the resistance to crack extension, which exists in the material at the crack tip. As the applied stress, and therefore the crack extension force, on the specimen increases, the resistance also increases primarily because the effective plastic zone at the crack tip, which is the main energy absorption process, becomes larger. Since the work-hardening rate of a material influences the stress-strain relationship, it will also influence the energy absorption process in the plastic enclave at the crack tip and hence should have an effect on crack propagation. A number of studies have been made correlating the strain-hardening exponent or the strain to tensile instability with the ability of a material to resist fracture. Gensamer1 concluded that a low-strain-hardening exponent would result in a steep strain gradient at the base of a notch. He reasoned that a large work-hardening coefficient would result in high-energy ab- sorption due to the increased area under the stress-strain curve. Larson and Nunes2 experimentally observed in Charpy tests on steels heat-treated to below 200,000 psi yield strength that the energy to failure in the fibrous mode, i.e., above the brittle-to-ductile transition temperature, was logarithmically related to the strain-hardening exponent. In order to avoid the complicating effects present in studying materials which undergo a brittle-to-ductile transition, Ripling evaluated the notch sensitivity of a variety of fcc metals with varying work-hardening exponents.3 The results indicated that the relative notch sensitivity, as determined from tests on specimens with a sharp notch, decreased with increasing values of strain hardening. Although the energy required for ductile or fibrous fracture increases with increasing work hardening, high-strength steels often exhibit improved crack propagation resistance when heat-treated to obtain low values of strain hardening.4,5 An analysis of whether low strain hardening is beneficial or detrimental to crack propagation resistance must depend on the particular fracture criterion involved. At temperatures where the material is relatively ductile and the development of a critical strain is required for fracture, high strain hardening increases the energy required to produce failure. In the transition region and below, however, a critical stress law appears to be valid6 and a low rate of work hardening may produce superior resistance to semibrittle crack propagation. The experimental program is aimed at studying these possibilities and determining the specific influence of strain hardening on the crack propagation resistance of several high-strength materials. MATERIALS AND PROCEDURE The alloys, chosen as representative of various classes of high-strength materials, are summarized in Table I. The heat treatments evaluated along with the smooth tensile properties are presented in Table 11. Pin-loaded sheet tensile specimens were employed to determine the smooth tensile properties. A strain gage extensometer (measuring range 0.200 in.) was used at a strain rate of 0.02 in. per in. per min. The work-hardening exponents were determined from the stress-strain curves generated in the smooth tensile tests and the assumption that the portion of the stress-strain curve beyond the yield point can be described by the power relationship: where a is the true stress, P is the true plastic strain,

Jan 1, 1969

By A. E. Perkins

fractured ingot will show a complete diagonal structure. If the temperature is lowered, the equi-axed zone is larger and the pine tree growth is less. A small ingot, though, is prone to this columnar structure, even though the casting temperature is kept down. The speed of cooling after solidification is slower in the hollow ingot than in the solid, therefore the granulation, which takes place after the crystals have formed from the liquid metal, is apt to produce larger grains than in the solid ingot. This is not a detriment. The original crystal size is of much more importance. The size of the grains due to this granulation constantly varies in response to mechanical work and subsequent heat treatment. Surface weakness, as shown by seaming and checking on the exterior when working or by cracking in hardening, is in some measure the result of the surface stresses of the ingot when cast. The temperature of the ingot mold or speed of freezing of the exterior of the ingot is of great importance and much seamy and cracked steel is caused by a too quickly cooled skin. Ingots that are turned or milled all over will not seam very much in working, in fact they are practically free from seams, whereas an ingot rolled without a preliminary machining operation is full of seams and cracks, some long and some short. It has been said that these short seams and cracks in the surface of the bar are the result of elongated depressions in the surface of the ingot and that if an ingot is cast very smooth it should give fewer surface defects. This is partly true, but an ingot cast very hot and having a very smooth skin will crack and seam very badly in the mill, as will the surface of an ingot poured very cold, which is very crinkly, because of the low temperature of the metal. The cause of the cracks and seams in one is not the cause of the cracks and seams in the other. The tube method of hollow drill steel manufacture is superior to the older method because of: (1) Greater freedom from external and internal straining; (2) the inherent small crystal size; (3) absence of harmful segregation, resulting in weakness of wall of hole. (4) less liability for steel to crack in inside of hole during forging or hardening; (5) toughening effect, arising from mild steel wall of hole limiting the intense hardening on quenching. Breakage and Heat Treatment or Rock-drill Steel By A. E. Perkins, Pittsburgh, Pa. Actual figures showing the superiority of one section or another are difficult to obtain. In a given size of steel, however, the cruciform sec -tion shows the most breakage; it is inherently a weak section. It contains less steel per foot than any other standard section of the same size and when rolled the wings tend to cool off setting up cooling stresses.

Jan 1, 1922

NEW MEMBERS The following list comprises the names of those persons who became members during the period Aug. 10 to Sept. 10, 1914: Members ALLEY, HARRY MCCAMMON, Mill Foreman .... Churchill Mining Co., Wonder,2 Nev. AMBLER, J. OWEN, Met..; ... Calumet and Arizona Mining Co., Douglas, Ariz. ANDERSON, JAMES WILLOUGHBY, Duell, Warfield and Duell, 2 Rector St., New York, N. Y. ANTISELL, FRANK L., Asst. Supt Raritan Copper Works, Perth Amboy, N. J. CARRINGTON, FRANK GAMBLE, Sec'y and Asst. Mgr., Standard Foundry Co., Anniston, Ala. CONKEY, CHARLES ROLLAND, Structural Draftsman, Barnett McQueen Co., Ft. William, Ont., Canada. COOK, PAUL RICHARDSON, Mill Shift Boss, Buckhorn Mill and Cyanide Plant, Buckhorn. Nev.

Jan 10, 1914

By J. P. Van Kleunen

9.3-1. Introduction. The demands of industry for handling materials at higher rates and at reduced costs have had a very significant effect on belt conveyor technology. Although the general appearance of the belt conveyor today is essentially the same as it has been for the past several decades, the similarity ends there. Each component comprising the conveyor system has been continuously improved through design and materials technology to enable present conveyor systems to operate at ever-increasing rates and reliability. For example, twenty years ago the strongest commercially available, fabric-reinforced conveyor belting had a tension rating of 50 lb per ply-in. Currently, fabric-reinforced belts are available with ratings of 350 lb per ply-in. and steel cable reinforced belting is available with tension ratings of 3000 lb per in. of belt width (3). These technological advances have therefore enabled the belt conveyor to not only attain acceptance as a preferred method for in-plant movement of bulk materials, but also to be used for long distance transportation of bulk materials, particularly in areas of adverse terrain. The information contained in this chapter is intended to assist the reader to make basic decisions regarding the use and application of a conveyor system. The design of an overland conveyor transportation system or an in-plant process conveyor is accordingly beyond the scope of this article. Many comprehensive technical works covering the design of a belt conveyor are currently available from the manufacturers of materials handling equipment (6, 7, 9, 11). The design handbook published by the Conveyor Equipment Manufacturers Association is particularly recommended (2). 9.3-2. Conveyor Capacities. One of the most important factors in determining the proper size of a conveyor system is the rate at which material must be handled. Although tables and charts are available to the conveyor designer to assist him in his selection of conveyor components, only the

Jan 1, 1968

By A. U. Seybolt, D. H. Haman

The rate of oxidation of the lowest nitride of chromium, Cr2N, was measured to be equal to the rate of oxidation of chromium metal. It was found that, while the presence of Cr2N in chromium does not affect the oxidation mechanism, a long exposure at high temperature affects the morphology of Cr2N in chromium, causing a massive internal nitriding along chromium pain boundaries. Marker expen' -ments showed that the rate of oxidation of Cr2N layers on chromium is determined by the rate of chromium diffusion through Cr,03. The rate of formation of Cr2N is determined by diffusion rate of nitrogen through Cr2N. This rate at 1000°C is around thirty times faster than the rate of oxiahtion. Evidence is presented which suggests that nitrogen from the air reaches the chromium through the Cr2O9 by migration through pores or cracks rather than by a diffusive process. IT has long been recognized that, when chromium or alloys containing substantial amounts of chromium are oxidized in air, some chromium nitride (Cr2N) is formed under the oxide scale. Although the presence of this nitride layer has often been described, there appears to have been no systematic study of the role played by the nitride during the oxidation process. Indeed, there have been conflicting re-ports'92 on the kinetics of oxidation of chromium and chromium alloys in air and in oxygen. However, it is now well-established'-5 that the rate-controlling process during the parabolic oxidation of chromium to Cr2O3 is chromium-ion diffusion through Cr2O3. Because of the importance of chromium-containing alloys as oxidation-resistant materials, it seemed desirable to investigate the behavior of chromium during oxidation with and without the presence of chromium nitride. Since a semicontinuous Cr2N layer forms relatively early during the oxidation of chromium in the air, chromium atoms must either pass out of or through the Cr2N layer to become incorporated in the growing Cr2O3 scale. Therefore, it seemed desirable to examine the oxidation behavior of the pure nitride. MATERIALS AND EXPERIMENTAL PROCEDURE The chromium used in this investigation consisted of slices of an ingot made from "five-nine" iodide chromium which had been argon-atmosphere melted in a Y2O 3-stabilized ZrO2 crucible in an induction furnace. The only impurity of any significance was 625 ppm of 0, which was usually reduced to a microscopically invisible amount by hydrogen annealing at 1400°C. However, one sample of chromium was used with the as-cast oxygen level as explained below. The samples were used after abrading through 600 Sic paper and then washing in toluene and alcohol. Both nitriding and oxidation experiments were performed in a vertical tube furnace connected to a glass vacuum system. 'This system was equipped with pressure measuring instruments for the range of 10 p to 1 atm, and a cartesian-diver pressure-control device was used in conjunction with a needle valve to allow control of pressure in the range of about 10 to 760 mm. The nitrogen or hydrogen gas was purified by passing through hot copper chips at 600°C, anhydrous calcium sulfate (Drierite), and liquid nitrogen. Oxygen gas was dried through the Drierite column and a dry-ice trap (-78°C). Changes in specimen weight were followed by a Pyrex helix used in conjunction with a cathetometer which could reproducibly be read to +0.001 cm, yielding an accuracy of about +0.2 mg. The spring was maintained in the cool upper part of the furnace tube where the temperature did not rise above about 35°C. The nitride in equilibrium with metallic chro-

Jan 1, 1964