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By C. G., Fink

The dissolution of gold by cyanide solutions was studied by determining the time required for the solvents to dissolve gold leaf. Minute traces, even 0.5 ppm, of sulphide ion retard the dissolution of gold, and this behavior cannot be accounted for by the presently accepted hypotheses involving oxygen-depletion or thiocyanate formation. On the other hand, traces of the salts of lead, bismuth, mercury, and thallium considerably accelerate the dissolution. The beneficial effect of lead is dependent upon the pH and cyanide ion concentration of the solution.

Jan 1, 1950

By Harry M. Mikami

Refractories are heat-resistant, generally nonmetallic materials used as the linings of furnaces or high temperature vessels in the steel, iron, nonferrous metals, glass, cement, lime, ceramic, chemical, petroleum, paper, and power and heat generation industries. Refractories must have structural strength at high temperatures but also, in many applications, must simultaneously resist chemical-physical corrosion-erosion from stags, metals, granular solids, or gases. Among the major uses are the pyrometallurgical processes for producing iron, steel, copper, aluminum, nickel, lead, zinc, etc. Rotary cement kilns, glass tanks, refineries, utility boilers, chemical and ceramic (including refractories) plants, and a myriad of other smaller scale users employ refractories in the high temperature parts of their operations. Thermal, chemical, and structural conditions under which refractories are used differ widely so there is a great variety of refractories to fill the various needs. Two major classifications are the "basic" and "acid" types. Basic refractories include magnesia and chromite, singly and in combinations, dolomite, and forsterite (olivine). The acid category includes aluminosilicates, alumina, and silica. There are a number of other specialized types such as carbon, graphite, silicon carbide, zircon, and zirconia that have important applications but are used in much smaller amounts than the major categories. Physically, refractories can be divided into bricks and shaped products on the one hand and unshaped or monolithic products (also termed specialties) on the other. There are many further subclassifications and divisions, a discussion of which is beyond the scope of this chapter; see Refs. 2 and 9. Raw materials for the principal basic refractories are magnesia and chrome ore. Magnesia, generally termed magnesite or periclase, is obtained mainly from seawater or saline brines extraction, but substantial amounts are produced from mined magnesite (MgCO3). Dolomite (CaCO3•MgCO3), another important basic refractory, is obtained entirely from mined sources. Acid refractory raw materials are: fire clays, flint clays, kaolin, and other natural clay minerals; aluminosilicate minerals such as kyanite, andalusite, sillimanite, pyrophyllite, bauxitic clays; calcined refractory grade bauxite, alumina from the Bayer process for the alumina group; and quartzitic rocks for silica refractories. The total value of all refractories shipped in the United States in 1974 was $989 million, a record to that date. Of this amount, about 73% represents bricks and shaped products and 27% is in nonshaped or monolithic products which comprise mortars, cements, castables, plastics, and ramming and gunning mixes. Fig. 15.4E.1 shows the rising value of all U.S. refractory shipments in the period 1948-1974. Values of brick and shapes paralleled

Jan 1, 1976

By Edwin B. Wilson, Joseph W. Leonard, Richard W. Borio

preparation of specification coals for the utility industry is approached from the standpoint of a cooperative effort with the power company to assure that the shipped product will be a noncorrosive coal. Selective mining, coal preparation, the use of additives, and coal blending are mine-site techniques proposed as means for upgrading corrosion-retarding constituents of utility coals (CaO and MgO) while, at the same time, reducing the concentration of those constituents of coal (Na20 and K,O) which cause corrosion. Data obtained from large-scale boiler testing in combination with bench-scale physical and chemical tests are used as a basis for the formulation of mine-site procedures to improve coal combustion utilization. Electric power generation remains the greatest market for coal in the United States. A major reason for this strong market has been the ability of the coal industry to supply a superior product for combustion while maintaining competitive prices. Now that the coal industry is engaged in intensive competition with nuclear power for future energy demand, it becomes ever more imperative that superior coal products are produced. One important problem when burning some coals is a liquid phase corrosive attack on boiler tube metal in the superheater and reheater areas of the furnace where steam temperatures may exceed 1050°F. In addition to causing power outages and high maintenance costs, corrosion is a continuing barrier to the future development of more efficient steam cycles which permit lower generation costs when using coal. Research methods of the past which have been directed at finding solutions which could be applied at the power plant site have been only partially successful and are generally costly. This paper contains a suggested --method of corrosion control through investigation of the problem at the source of the trouble—the coal supplier facility. It is proposed that mine-site pre-ventative procedures be considered as an effective means of cooperative corrosion control between the power company and the coal supplier. Economic justification must be applied to the individual situation. This paper is based on recent work by Combustion Engineering, Inc. and the Coal Research Bureau of West Virginia University under a contract from the Department of the Interior Office of Coal Research.',' Results which are of importance to this discussion may be summarized as follows: 1) The alkali minerals of coal (Na2O and K2O), as measured by an acid leaching process, can be related to corrosion rate in utility boilers. As these constituents increase in a coal product, its corrosiveness can be expected to worsen. 2) The alkaline-earth minerals contained in coal, reported as total CaO and MgO reduce corrosiveness 2s their concentration increases. 3) Naturally occuring, alkaline-earth-bearing materials, such as limestone and dolomite, may be added to a coal to reduce its corrosiveness. 4) Coals with very low iron contents tend to be less corrosive. These results provide the groundwork for examination of the system of operations which occur at the supplier facility from the seam face where mining is begun to the point of loading for shipment. The Mining System Fig. 1 is a cross section of one of the typical coal seams (designated coal A) that was boiler tested during this research program. This seam is overlain by material which consists primarily of a gray-black shale. In the lower third of this seam, there exists a thin rock parting of less than 4 in. in thickness which is consistent throughout the seam. The floor material is fireclay. In order to examine mineral distribution throughout this particular seam, the Coal Research Bureau collected a

Jan 1, 1971

By Noel Stearn

WHEN the Age of Machinery was suddenly thrust upon civilization about the beginning of the nineteenth century, an unprecedented demand for mineral resources sprang up. This demand brought about the rapid development of the known ore deposits and the discovery of such other deposits as could be encountered by energetic and canny pros-pectors. Thus in the countries now reasonably ac-cessible nearly all orebodies have been located except those which are totally concealed even from the eyes and "senses" of experienced and expert prospectors. The high rate of exhaustion of known ore deposits and the necessity of looking farther and farther ahead for raw materials as a matter of insurance on the stu-pendous capital outlays involved in mining, develop-ment, and conversion operations, have resulted in excep-tional activity in three different fields of effort. The first is purely geographic. Prospectors are now pene-trating the few hitherto inaccessible regions in the hope of stumbling upon exposed ore deposits or locating visible indications of their presence. The second is chemical. Industrial chemists and metallurgists are seeking to facilitate the exploitation of lower grade ores to find methods of recovering valuable metals from common substances. In the third field of effort. lie the activities of the economic geologist and the mining engineer, who en-deavor to locate concealed ore deposits, which would remain hidden from the prospector, no matter. how expert or conscientious he might be. Obviously the task which such a man must face is both exacting and indefinite, and the tools which he has heretofore been permitted to bring to it are, for the most part, abstract-a knowledge of certain fundamental princi-ples and processes involved in the origin, occurrence, structure, and distribution of deposits. of natural re-sources and of the rocks which form the environments of those deposits, and a process-of reasoning by analogy supplemented by the .use of the diamond drill, or such artificial exposure as the test pit, trench, shaft or tunnel. His primary efforts are usually bent on acquiring a knowledge of the distribution of the rocks-as accurate -is possible-which is a natural prerequisite to any conclusion as to how they became so distributed. Over very extensive areas, however, he meets. the extreme difficulty of being unable to see the rocks, except at rare intervals, since .they have been concealed by an overburden of glacial material, of alluvium, of soil, or of other rocks.

Jan 9, 1928

By M. E. Nicholson

The effect of boron on the austenitic transformation rate of iron is smaller than on low carbon steels. The influence of austenitizing temperature on B-Fe is the reverse of its influence on steels. THERE have been many studies made of the influence of boron on the hardenability of steel, but apparently none has been made of its influence on the y-a transformation of pure iron. There are several facts suggesting that boron should have a pronounced effect on the transformation rate of iron. First, Simcoe et a1.l indicated that boron reduces the nucleation rate of ferrite and bainite. Second, they showed, along with others,', " that the lower the carbon content of steel the greater the influence of boron on hardenability. If this trend extends to pure iron, the influence on rate of ferrite formation should be considerably greater for iron than for medium carbon steels. According to Rahrer and Armstrong," the multiplying factor for boron in pure iron should be about 2.40, compared with 1.50 in a 0.35 pet C steel. According to an extrapolation made by Grange and Mitchell,' the effect should be even greater, and the multiplying factor should be about 3.5 in iron. Many investigations of the boron influence'.7, 2, 5 indicated that boron is effective only when in solid solution. On the other hand, Chandler and Bredig" suggested that boron increases hardenability by combining with nitrogen, thereby preventing formation of AlN, which catalyzes the decomposition of austenite. If their hypothesis is valid, boron should have no effect on an alloy free from nitrogen. Digges et al." showed that so far as low nitrogen high purity Fe-C alloys are concerned this is not the case. No experiments, however, have been made on low nitrogen iron. To determine whether or not boron has an effect on low nitrogen iron and, if an effect exists, to determine whether it is as large as predicted from the investigations of boron treated steels, the following work was performed. Because of the rapidity with which iron transforms from austenite to ferrite at even a moderate degree of supercooling, it was decided to study the influence of boron on the transformation rate of iron by determining the effect of quenching rate on the temperature of the beginning of transformation. The technique, essentially that used by Greninger' and Duwez,H consisted of heating small specimens, 0.1 in. sq and 0.010 in. thick, in an atmosphere of purified helium with a resistance heater coil, and then quenching the sample in a jet of helium gas. At the time the jet was applied, the heating coil was removed from around the sample. The sample was suspended in the furnace on 30 gage chrome1 and alumel wires, one welded to each side of the specimen, which also served as a thermocouple for measuring the specimen temperature. Specimens were prepared from vacuum-melted iron obtained from the National Research Corp. which was rolled to a thickness of 0.060 in. and then decarburized in wet hydrogen for 51/2 hr at 700°C. This treatment also removed any boron present in the iron. The resulting iron contained 0.001 pet C. 0.0002 pet N, and 0.005 pet 0. One half of the piece was then boronized by surrounding it with 325 mesh boron powder and heating it for about 2 hr at 900°C in H,. The boronized iron was then homogenized at 1100°C for 24 hr. The iron boride case formed by boronizing was removed by grinding 0.010 in. from each side of the plate, and the piece was finally rolled to a thickness of 0.010 in. The resulting alloy contained

Jan 1, 1957

By R. W. Raymond

PROFESSOR W. P. BLAKE, in a note to his Catalogue of California Minerals, pointed out that the milling districts of the Pacific slope are arranged in parallel zones, following the prevailing direction of the mountain ranges. This interesting generalization has been more frilly illustrated and connected with the geological history of the country by Mr. Clarence King, who sums up the observed phenomena as follows : " The Pacific coast ranges upon the west carry quicksilver, tin, and chromic iron. The next belt is that of the Sierra Nevada and Oregon Cascades, which, upon their west slope, bear two zones, a foot-hill chain of copper mines, and a middle line of gold deposits. These gold veins and the resultant placer mines extend far into Alaska, characterized by the occurrence of gold in quartz, by a small amount of that metal which is entangled in iron sulphurets, and by occupying splits in the upturned metamorphic strata of the Jurassic age. Lying to the east of this zone, along the east base of the Sierras, and stretching southward into Mexico, is a chain of silver mines, containing comparatively little base metal, and frequently included in volcanic rocks. Through Middle Mexico, Arizona, Middle Nevada, and Central Idaho is another line of silver mines, mineralized with complicated association of tli6 base metals, and more often occurring in older rocks. Through New Mexico, Utah, and Western Montana lies another zone of argentiferous galena lodes. To the east, again, the New Mexico, Colorado, Wyoming, and Montana gold belt is an extremely well-defined and continuous chain of deposits." These seven longitudinal zones or chains of mineral deposits must

By John A. Church

Jan 1, 1903

By C. S. Roberts

The creep mechanism and kinetics of fine-grained magnesium have been studied over the temperature range 200&apos; to 600°F. As a result of a photographic study of microstructural changes, transient and steady-state creep components have been correlated with slip, subgrain formation, and cyclic deformation at the grain boundaries. THE approach of this research has been the blend of a quantitative study of the creep strain of polycrystalline magnesium as a function of time, stress, and temperature with direct microstructural observations of the operative deformation processes. The validity of the conclusions is dependent on the condition that the microstructural changes seen on the polished surface qualitatively represent those occurring in the bulk of the metal. The work was intended as much to lay a background to a study of highly creep-resistant magnesium alloys as to provide a description of the behavior of the base metal itself. The spectroscopic analysis of the electrolytic magnesium used in this study is as follows: Al, 0.009 pct; Ca, <0.01; Cu, 0.0011; Fe, 0.021; Mn, 0.012; Ni, 0.0004; Pb, 0.0012; Si, <0.001; Sn, <0.001; and Zn, <0.01. The impurity level is approximately that of commercial magnesium alloys. The original ingot was melted under Dow type 310 flux and cast as a 3 in. diam billet. It was extruded into 1 in. flat stock under the conditions: billet preheat 800°F (1 hr), container and die temperature 800°F, speed 3 ft per min, and area reduction ratio 45:1. The extrusion process was chosen in preference to rolling and recrystallization because it allowed easier grain size control from specimen to specimen. The grains of the extruded metal were fairly equi-axial and uniform in the size range of 4 to 6 thousandths of an inch. The preferred orientation of basal planes about the transverse direction was determined by an X-ray diffraction surface reflection method. A beam of filtered copper radiation was directed at an angle of 17" to both the transverse direction and the surface yet perpendicular to the extrusion axis. Analysis of the (002) diffraction arcs in the resulting photographic patterns gave an approximate intensity distribution along the great circle which extends through the center of the basal plane pole figure and to the extrusion axis poles. Successive layers of metal were removed by macro-etching between exposures. The extruded texture is relatively sharp, but the most significant point is the position of the maximum basal plane pole density and its variation with depth below the surface. Fig. 1 shows that this maximum is rotated 15" from the normal at the surface toward the extrusion direction. Such an inclination has been reported for extruded 1 pct Mn and 8 pct A1-0.5 pct Zn alloys.&apos; The inclination decreases until the maximum splits at about 0.025 in. depth into two elements of equal and opposite rotations from the ideal. The double texture persists to as great a depth as was experimentally convenient to examine. It probably continues to the very center of the extrusion. There is no great change in the sharpness of the individual elements of the texture with depth. A plate of metal about 0.015 in. thick at the surface of the extruded stock was produced by etching. A transmission diffraction pattern was made for the purpose of determining any preferred orientation of a direction in the basal planes. Relatively uniform {loo) and {101) rings were produced. There is little tendency for parallelism of a given direction in the plane with the projection of the extrusion axis on it. The creep specimens were machined from 6¼ in. lengths of the extruded stock. Creep was measured on the reduced section, ½x1/8X2¼ in. long. This section was electropolished on one side for the studies of microstructural changes during creep. An orthophosphoric acid-ethyl alcohol electrolyte was used under the conditions recommended by Jacquet.² Hand polishing was used for previous mechanical preparation. Electropolishing was continued until all mechanical twins had been removed. The electro-polished surface was protected from oxidation during creep testing by a thin layer of silicone oil. All micrographs were taken at room temperature on conventional metallographic equipment and after removal of the oil film. The creep tests were performed with machines which have been described in detail by Moore and McDonald." Five testing temperatures, 200°, 300°, 400°, 500°, and 600° ±3°F were used. Difference in temperature between the two ends of the specimen reduced section was 2°F or less. The testing was done at constant load. Strain readings were taken as frequently as necessary to develop usable creep curves. Tensile Creep vs Time, Stress, and Temperature A definition of terms is necessary. Whenever successive sections of a creep strain-time curve show decreasing, constant, and increasing slope with time they will be termed primary, secondary, and tertiary

Jan 1, 1954

By D. F. Coolbaugh

Successful mine exploration requires sound planning and modern exploration techniques, but it also requires perseverance and the right timing. The La Caridad mineral area has been known for over 70 years, but as with many mines, it was not "discovered" until viewed under new economic conditions and exploration philosophies. Present exploration of the La Caridad area began in 1964 and was carried out under a joint Mexican Government-United Nations Project. Detailed exploration was begun by Asarco Mexicana S.A. in late 1968. The geology of the La Caridad deposits conforms, generally, to the "porphyry copper" deposits of Arizona. However, breccias and pegmatites play a very important part in the emplacement of mineralization.

Jan 1, 1972

By H. A. Wriedt

Zinc-vapor pressures in equilibrium with bcc solutions of zinc and iron at 703.5", 757", 793", and 900°C were measured by an isopiestic method. Thermody-na?nic properties of zinc in these solutions were derived directly and those of iron with a Gibbs-Duhem integration. Zirzc and iron exhibit large, positive, and moderately temperature-sensitive deviations from ideality. Excess enthalpies and Gibbs energies are positive in the ranges studied. It has been establzshed in relating published phase equilibria to the Gibbs energies of forming solid solutions that positive departures from ideality also exist in the fcc solutions. Tlze stability, as defined by Darken, of the bcc solutions is small but positive at 703.5"C. Its decrease with decreasing temperature indicates that a miscibility gap may exist in the stable or metastable bcc solutions at lower temperatures. The changes of thertnodynanlic properties relatable to changes in magnetic state are minor compared to other changes due to alloying. The accuracy with which the relation between lattice parameter and composition of the bcc solutions is known has been improved. Zinc increases the lattice parameter of a iron by O.ZOZA per unit atom action zinc to at least NZn = 0.25. TO our knowledge, only Ciganl has previously investigated thermodynamic properties of the bcc solutions of the Fe-Zn system. He measured zinc-vapor pressures in the temperature range from about 320" to 360°C by an effusion technique. We have measured the vapor pressures of zinc in equilibrium with bcc solutions of zinc and iron at 703.5", 757", 793", and 900°C by an isopiestic technique. This investigation and the pursuant thermodynamic computations are part of a program for studying several properties of these solid solutions. In the appendix we report a remeasurement of the relation at room temperature between the lattice parameter and zinc content. Related work not reported herein embraces measuring the diffusivity2 of zinc in ferrite at 700" to 900°C and the Curie point temperature3 as functions of composition. EXPERIMENTAL METHOD AND APPARATUS Purified iron at a series of constant temperatures was saturated with zinc at a series of constant zinc-vapor pressures, the range of conditions being so limited that the equilibrated solid solutions were ferri-tic. The equilibration was conducted in long capsules, Fig. 1, that had been evacuated, gettered with titanium, and sealed. The purified iron, part of a vacuum-melted ingot of electrolytic-iron stock (Glidden Co. 1044-grade), had the impurity contents listed in Table I. It was used in the form of millings about 0.001 in. thick. A zinc of 99.999 pct purity (United Mineral and Chemical Corp.) and later one of 99.9999 pct purity (Cominco Products, Inc.) were used, with no observed difference in results. Sufficient zinc was placed in the capsule (separate from the iron and kept at a different temperature) to supply the vapor phase and the iron alloy, while leaving a pool of pure liquid zinc throughout the run. The imposed temperature of the residual zinc pool fixed the vapor pressure of zinc throughout the capsule; condensation was avoided at other locations by making this the lowest temperature in the capsule. Two common complications of nonisothermal systems were, we believe, effectively absent from ours: first, molecular species other than monatomic have no appreciable concentration in zinc vapor at 700" to 900~~: second, the development of zinc-pressure differentials in the capsules was suppressed by use of relatively large-diameter tubing and the absence of diluents in the zinc vapor other than desorbed impurities. The specimens and zinc pool were located at two isothermal zones (each ranging within 1°C over several inches) of a wire-wound, 37-in.-long vertical-tube furnace. The required temperature distribution was achieved by external adjustment of the currents in three electrically isolated windings. The temperatures of the isothermal zones were controlled independently by ther-

Jan 1, 1968

By C. W. Hoffman, W. R. Hinken

Probability sizing, a fairly recent development in the field of particle separation, is now under investigation to determine its value to the mining industry. The method employed is probability sizing through a vibrating network of decreasing screen openings. While probability sizing is not new, the possibility of using it for coarse, highly abrasive ores at high tonnage rates has only recently appeared to merit practical consideration. The advantages of probability sizing vs. conventional screening methods are: (1) reduced space requirements for a high capacity unit, (2) fewer moving parts, (3) more versatile product sizing selection, (4) reduced maintenance requirements, and (5) lower power consumption. Screening is a necessary part of virtually every crushing circuit. At some stage in the process, particle separation becomes a controlling factor in the operation. The basic type of screen in use today is the vibrating unit, which usually employs a mechanical vibrator of one type or another to obtain sizing and material transportation across the screen surface. The vibrating screen has its limitations and inherent problems. Operators must live with: (1) high maintenance — worn rods, screen cloth, spacers, cross members, chutes, etc., (2) low capacity in relation to floor space requirements, (3) extreme noise levels, (4) high power consumption, and (5) structural problems in the screens and supporting steelwork. All plant operators have become tolerant of these drawbacks through the years, and little innovation has been developed in screening. The vibrating screens in use today incorporate improved metals, more efficient power sources, better lubricants, and increased manufacturing skill, but the basic machine itself remains unchanged. Screening is a relatively small part of most plants&apos; operating expenditures and gets relatively little attention from research and development. The HiProb sizer is a new approach to the problem of particle separation on a high tonnage basis. Developed by Dr. Fredrik Mogensen (president of Fred-rik Mogensen, A. B. of Djursholn, Sweden), this unit has found its primary acceptance in the sizing of wet or dry materials in the fine ranges. Climax has been working cooperatively with Mine and Smelter Supply Company, the United States licensee, on the adaptation of the sizer to obtain consistent recovery at a high tonnage rate on a — 3/8-in. separation. This was a new application for the sizer and opened up a whole new field of problems. Dr. Mogensen&apos;s machine utilizes the control of normal probability of falling particles and is designed to eliminate some of the undesirable features of vibrating screens mentioned earlier. The machine is light, compact, consumes less power than conventional screens and has a low noise level. PRINCIPLES Probability sizing is a process designed to allow solid particles to segregate with a high ratio of the materials reporting into their respective size fractions with a minimum amount of misplaced particles. Sizing is defined in this paper as segregation of dry solid particles into fractions of comparable sizes. Probability is usually estimated as the ratio of the number of ways an event might occur vs. the total number of allowable ways. The probability process described depends upon the fact that particles falling through a network will segregate across the sizing surface even though all openings are larger than the particles. The degree of segregation is dependent upon the particle size and the trajectory applied by the sizing network to each falling particle. Specifically, the process utilizes a maze made up of screen cloth to control the path of a particle in free fall as illustrated in Fig. 1. The usefulness of this probability sizing process is dependent upon the degree of efficiency of an effective maze. Primarily, a maze must be extremely flexible to meet the multi-faceted nature of solid particles and, at the same time, the degree of control must be reproducible so that a desired separation is predictable. Dr. Fredrik Mogensen has formulated a maze that is not only flexible and easily controlled, but, mote importantly, easily adaptable to a working machine.

Jan 1, 1970

By T. C. Poulter, B. M. Caldwell, D. E. Brink

The flash X-ray has been used more than a decade to study the configuration of the jet from a shaped charge. The high-speed, rotating-mirror smear camera has provided time-distance graphs of detonations and shock fronts in transparent materials, and the high-speed framing camera has given pictorial representations of the progress of explosive phenomena. Adequate means for measuring the paths and velocities of all parts of the shaped-charge cavity Iiner during the collapse phase have not existed heretofore. A technique enabling the single-lens framing camera to make stereoscopic photographs of the cavity liner while it is collapsing has been developed. Analysis of this photographic record gives the directions and velocities of various parts of the Iiner surface, permitting direct quantitative measurement where this has previously been impossible. Significant improvements in shnped-clrarge design are expected to result. INTRODUCTION The familiar oilwell jet perforating charge, generally referred to as a "shaped charge", is related to the Mun-roe charge first described by C. E. Munroe in 1888 and later by Neumann in 1910. It differs in construction from the Munroe charge in that its cavity is lined with some inert material (usually metal)&apos;, and it differs in performance by projecting a fast jet of dense liner material against the target instead of a stream of expanding detonation products. Fig. 1 represents a typical shaped charge in axial cross section. The charge is circularly symmetrical about its longitudinal axis. The cavity at the right is lined with metal, usually copper; and, with the exception of air, the liner is otherwise completely empty. High-explosive material is intimately in contact with the convex surface of the liner and extends in the other direction to the booster. This is a pellet of high explosive having somewhat different characteristics and serves to couple the detonator to the main charge. When the detonator is fired, a small hemispherical reaction zone of very high temperature and pressure occurs at its output end. The booster responds, adding its own latent energy to the reaction, thereby initiating the main charge. The reaction progresses throughout the main charge at a velocity of 7 to 8 mm/microsecond until all the explosive material has reacted. With a reaction pressure of about 160,000 atm, the surrounding material is moved rapidly away from the high-pressure zone. As the detonation proceeds along the cavity liner, moving from apex to edge, the liner is collapsed toward the axis of the cavity, where liner material from all parts of the concave surface converges. A zone of extraordinarily high pressure results. with only one escape path—outward along the axis. The particles from the liner, thus, become a jet of very high velocity, with a density characteristic of the material from which the liner was made. The kinetic energy of the jet, concentrated in a small area of the target, has great penetrating power. It overcomes the strength of any target, and the target material crumbles or deforms plastically to escape from the path of the jet. An unlined cavity charge, on the other hand, projects a turbulent body of hot gaseous material against a target and erodes the exposed surface. With equal quantities of explosive, the penetration effectiveness of an unlined charge is a small fraction of that of a lined charge. Given an explosive charge with a detonator at one end and an axially symmetrical metal-lined cavity at the other, one has a perforator of considerable potency. To maximize the penetrating and other desirable effects,

By S. Storchheim

MORE and more attention is being paid to the bonding of metals in their solid states. For a better understanding of this technique for joining metals and how it is affected by changes in temperature, pressure, and time at temperature and pressure, a detailed report concerning nickel to aluminum bonding has been published.&apos; In order to broaden the knowledge accrued, some additional work concerning solid state joining of aluminum to copper and aluminum to zirconium was performed. The investigation of the Al-Cu system was considerably more extensive than the investigation of the Al-Zr system. For the A1-Cu system, not only were tensile sudies made but intermetallic penetration rate investigations also were carried out. The effect of temperature on intermetallic penetration rate for the A1-Cu system was determined at 11 tsi pressure, held 2 min. Procedure Apparatus: The hot pressing technique was the means of solid state reaction used and required the equipment depicted in Fig. 1. The following procedure was involved: The two metals to be reacted were placed in an aquadag-lubricated 18-4-1 tool steel die, 16 in. high by 1.440 in. ID, between punches of 1.366 in. diam made of the same material. A thermocouple well was located in the die body 3½ in. down from the top of the die, while another well was located centrally in the bottom punch 8½ in. from the bottom of the die. This die assembly was located in three cylindrical ceramic heating furnaces placed in tandem. Each furnace was controlled individually by a Variac power transformer. In turn, the die and furnaces were placed in a water-cooled stainless steel pot which could be evacuated. A cover, which contained a centrally located Wilson seal with an 18-4-1 1 in. diam ram running through it, was bolted on the pot. After sealing, the pot was evacuated by a roughing pump to 200 microns pressure, after which a diffusion pump was used to bring the pressure down to 5 to 15 u. At this pressure, the furnaces were turned on. As soon as they started to heat, out-gassing of the entire unit raised the pressure to 30 to 400 p. By the time the specimens were at temperature ready to be pressed, approximately 4/2 hr, the vacuum pumps had re-established the 5 to 15 u pressure. Once the desired temperature was reached, the required pressure was applied for a predetermined length of time to the 1 in. ram, through to the top punch, and to the specimen. When the time for keeping the specimen under pressure had elapsed, the pressure was released, the energizing coil current turned off, and the assembly allowed to cool. After cooling, the die was removed from the pot and the specimen was ejected. Specimen Preparation: Two different types of specimens were made for this investigation. One was for subsequent tensile testing, while the other was for determination of intermetallic alloy zone penetration into the parent metals. Tensile Bars—Commercially rolled copper pieces in. thick or zirconium sheet pieces 1/32 in. thick and 1.366 in. diam were placed between commercial 2-S aluminum rod 1 in. thick and 1.366 in. diam. This sandwich in turn was slipped into a 2-S aluminum sleeve 1.438 in. OD and 1.370 in. ID. This sleeve lined the couple up and prevented the aquadag lubricant from getting in between either the A1-Cu or Al-Zr interfaces. Immediately prior to the specimen assembly, the copper or zirconium was abraded on the flat surfaces with 320 grit silicon carbide paper, producing clean smooth surfaces. The aluminum was chemically cleaned just before assembly by: l—degrease in acetone, 2—distilled water rinse, 3—immersion for 3 min in 5 pct NaOH at 70" to 80°C, 4—distilled water rinse, 5—immersion for 2 min in 50 pct HNO3 solution at room temperature, 6—distilled water rinse, and 7—drying in a blast of gas. After the A1-Cu sandwiches were hot pressed and ejected, the specimens were machined such that the aluminum sleeve was removed, and the remaining aluminum was then threaded; the bar so produced was tested later for tensile strength. In all the instances where Al-Cu couples were tested, the specimens broke during the test at the Cu-A1 interface and never within the aluminum or copper. The ultimate tensile strength values at times showed considerable scatter for a set of given reaction conditions. Because of this, as many as three to five specimens were made for a particular set of conditions. The trend of the average tensile strengths obtained was not as conclusive as was the trend of the maximum tensile strengths, the latter values being obtained under optimum reaction conditions. Therefore, the values of ultimate tensile strength given herein are maximums.

Jan 1, 1956

The Howe Memorial Lecture, in memory of Henry Marion Howe, Past President of the Institute, was authorized in April, 1923, as an annual address to be delivered by invitation under the auspices of the Institute by an individual of recognized and outstanding attainment in the science and practice of iron and steel metallurgy or metallography, chosen by the Board of Directors upon recommendation of the Iron and Steel Division. The following were the Howe lectures and lecturers for the years indicated 1924 What is Steel? By Albert Sauveur. 1925 Austenite and Austenitic Steels. By John A. Mathews. 1926 Twenty-five Years of Metallography. By William Campbell. 1927 Alloy Steels. By Bradley Stoughton. 1928 Significance of the Simple Steel Analysis. By Harry D. Hibbard. 1929 Studies of Hadfield&apos;s Manganese Steel with the High-power Microscope. By John Howe Hall. 1930 The Future of the American Iron and Steel Industry. By Zay Jeffries. 1931 On the Art of Metallography. By Francis F. Lucas.

Jan 1, 1923

THE CHAIRMAN (EDWIN LUDLOW, Lansford; Pa.).-Mr. Wang&apos;s paper reminded me that some years ago I was asked if I would not go into the Tien Tsin district and take charge of Americanizing a Chinese mine. They said the trouble was that, while wages were only 9 c. a day, the coke cost $2 a ton delivered to the cars. Reading Mr: Wang&apos;s paper would indicate the need of a little Americanization in the Manchurian field. Wages are only 40 c: a day, yet the cost is $3.60 a ton. An efficiency engineer would have an excellent opportunity in that field. T. T. READ, New York, N. Y.-It is always true that low-priced labor is inefficient, wherever we find it; for example, in Japan, where wages are low, but not so low as in Manchuria, working costs are not relatively much lower than ours. Mr. Padshah, describing his experience in India, once told me that, while wages were only about one-fifth as high

Jan 4, 1918

The Howe Memorial Lecture, in memory of Henry Marion Howe, Past President of the Institute, was authorized in April, 1923, as an annual address to be delivered by invitation under the auspices of the Institute by an individual of recognized and out- standing attainment in the science and practice of iron and steel metallurgy or metallography, chosen by the Board of Directors upon recommendation of the Iron and Steel Division. The follow- ing were the Howe lectures and lecturers for the years indicated: 1924 What is Steel? By Albert Sauveur. 1925 Austenite and Austenitic Steels. By John A. Mathems. 1926 Twenty-five Years of Metallography. By William Campbell. 1927 Alloy Steels. By Bradley Stoughton. 1928 Significance of the Simple Steel Analysis. By Henry D. Hibbard. 1929 Studies of Hadfield&apos;s Manganese Steel with the High-power Microscopa By John Howe Hall. 1930 The Future of the American Iron and Steel Industry. By Zay Jeffries. 1931 On the Art of Metallography. By Francis F. Lucas.

Jan 1, 1937

By T. H. Ramsey, Richard Shield

A process has been developed for fabricating thin-film resistors that are compatible with integrated circuits. Films are produced by evaporation of single refractory metals using an electron beam heating source. Resistor paths are then made using standard photoresist etching techniques. A low-temperature coefficient of resistance is obtained by control of nucleation during deposition of the film. One application of the process has been the development of a discrete resistor used for current setting in linear integrated circuits. Multiple thin-film resistors were formed on oxidized silicon substrates using molybdenum metal as a source. An evaporated protective layer of SiO2 over the resistor prevents resistance changes which might occur during subsequent high-temperature processing. Properties of a typical resistor are as follows: R = 15.7 ohm per sq, tolerance surface dimensions = 0.028 by 0.028 in., stable after 4000 hr at 0. 75 w without heat sink. THIN-FILM resistors have been investigated for many years with a large selection of usable resistors resulting from a wide variety of materials. Many of the processes necessitate a high degree of complexity but in nearly all cases the conclusions have been that the materials used in each case were acceptable provided the deposition process was reproducible and could be controlled sufficiently to give the required tolerances. It is our opinion that simplicity is still the key to thin-film resistor fabrication. In this regard, the single metal is obviously the simplest process to control, provided all the necessary properties can be obtained. The idea is not original in this laboratory by any means. Others have taken this approach.&apos; It has been demonstrated that a fairly wide range of resistivities can be obtained by careful control of deposition parameters for any given metal, and by selection of several single metals a very broad range of stable resistors can be obtained. The transition from one metal to the next is made when a film becomes too thin for adequate process control or long-term stability. A great deal of emphasis is once again being placed on the thin-film resistor. Although they have been thoroughly studied in the past, new applications have been found that require the properties obtainable only from thin-film resistors. Integrated circuits, in general, are advancing toward higher speeds and radiation environments which require replacement of the present diffused resistors. Linear circuits in particular are requiring high-power, high-precision resistors for the more advanced applications. The particular requirements of some linear circuits are such that a discrete resistor is required. The resistor described in this paper was developed as a 15.7-ohm precision discrete resistor for use in a current regulating circuit requiring a +2 pct end of life overall tolerance, a dissipation of 750 mw, and the ability to operate over a fairly broad temperature range (i.e., a low temperature coefficient of resistance, TCR). State-of-the-art integrated circuit and silicon processing technology lends itself well to the fabrication of thin-film resistors. Not only is the resistor thin film well-suited to integration on individual circuits, but the oxidized silicon surface provides one of

Jan 1, 1969

By Dean Goodermote, Carla S. Stone

I Introduction Coal fuels China. Roughly 70 percent of all commercial energy demand is supplied by domestic coal production and with the recent Chinese opening to the West, the Chinese Coal Industry may figure prominently in the export market as well. Because of the importance of China&apos;s coal industry to the future of China and the Pacific Rim energy balance, this paper reviews the industry and offers some cautious projections for its outlook. II Energy&apos;s Position in the Current Political and Economic Climate Traditionally, Chinese society has been dominated by the policies of its most important government leaders. Deng Xiaoping, Vice Chairman of the Communist Party is the current leader of China. Deng and his proteges are pragmatists. Although China&apos;s government structure is based on Marxist/Leninist tradition, Deng and his followers are promoting experiments with market economics and expanded relationships with Western Countries, which have encouraged foreign investment in China. Energy companies represent just one type of industry that is interested in helping the Chinese to develop their abundant natural resources. Although China&apos;s leadership is committed to a program of economic modernization, that program currently is experiencing what the Chinese government terms "readjustment". Readjustment cuts back in imports due to deficient foreign exchange and deemphasizes heavy industry, while it encourages agricultural and consumer goods output and, most imporant, energy production. Increased Chinese coal and oil production is essential both to fuel industry and, equally important, to provide foreign exchange. If sufficient energy production is not forthcoming, then economic growth will be severely retarded. China&apos;s 1979 per capita GNP of $260 is only slightly better than the weighted average achieved by low income countries of $230. (1) Delays in growth could lead to social unrest, threatening the position of the current leadership. Since there is no institutionalized mechanism for leadership succession and policy continuation, it is reasonable to assume that leadership changes could result in energy policy changes. III Energy Consumption Energy production is important to China&apos;s future economic health as highlighted by the World Bank. If China&apos;s economy grows rapidly, 5 percent to 6 percent during this decade, the Bank noted, a significant energy shortfall could occur as early as 1985. This state of affairs contrasts sharply with China&apos;s current position as a net hydrocarbon exporter. (2) To assure a healthy economic future, China&apos;s leadership is attempting to reduce its rate of increase in energy demand through conservation as well as to boost energy output. A massive conservation promotion program has been underway since 1979 and there is much room for improvement. China&apos;s industrial sector is only about half as energy efficient as is U.S. industry. (3) During the last two decades, each percent of increase in GNP has been accompanied by a 1.8 percent of increase in energy consumption. (4) This compares rather poorly with the United States where a less than one-to-one relationship exists. IV Energy Supply The short term prospects for oil production are uncertain. Production increases were rapid in the 1960&apos;s and early 1970&apos;s, averaging 20 percent annually, but most of this increase came from one field, Daquing. Now that Daquing&apos;s production has peaked and the offshore potential has yet to be developed, petroleum production has maintained a plateau of 2.1 million b/d, at least temporarily, of which approximately 15 percent is exported. (5) Output

Jan 1, 1982

By Thomas Fraser, David R. Mitchell

THE primary purpose of the loading plant is to transfer the finished product from the preparation machines to the railroad car, truck, or barge in which it is to go to market. Secondary purposes of the loading plant are: to prevent excessive degradation of sizes during loading, to reduce segregation as much as possible, and to prevent excessive quantities of very good or off-grade coal from entering any one car. Nonuniformity of consignments is one of the chief sources of complaints by consumers and coal merchants. A properly designed loading plant will do much to reduce complaints and insure uniformity, not only from shipment to shipment but also in each individual consignment along the length of the car and in cross section. DEGRADATION IN STORAGE, LOADING AND SHIPMENT The object in loading is not only to handle the coal without breakage and segregation, but also to produce a well-trimmed load that will ride to its destination without spillage o~ breakage en route. The small sizes present in a car-of prepared coal as received by the purchaser consist of: missed small sizes not screened out in the preparation plant, breakage during loading, and breakage caused by handling en route. For domestic sizes of anthracite shipped from the Pennsylvania anthracite field to Atlantic coast cities, the dealers&apos; loss because of breakage in loading and shipment amounts to from 2 to 5 per cent and for anthracite shipped to Middle West cities, the loss is 8 to 9 per cent. This difference is in part because dealers in the Middle West rescreen their coal more thoroughly than is usual in the East. One dealer handling Illinois No. 6 coal shipped from southern Illinois mines to Chicago reports an average size loss of 10 per cent when lump coal is unloaded with a fork. This runs as low as 5 per cent for carefully loaded coal and as high as 15 per cent for carelessly loaded coal. An Ohio dealer estimates the degradation in loading and shipment of West Virginia coals consigned to Ohio cities as follows: Pocahontas lump

Jan 1, 1950

By C. R. Breck

THERE has been a running discussion over the-past several years with respect to the life and adequacy of our natural gas reserves.. Some of the experts agree on one phase of the subject at least--that eventually it will be necessary to augment deliveries of natural gas in the northern markets by the development of a more or less comparable synthetic gas made from coal. The purpose of this paper is to point out: 1. It may be later than a good many people think-the demand for additional domestic and commercial pipeline gas in at least one section of the North will probably be felt rather keenly before an adequate synthetic pipeline-gas project, developed on economic lines, could be completed, even if &apos; initiated in the near future. 2. The evidence is considerable that such a project would be technically sound and economically self-supporting, although the margin of profit at first might be so small and the magnitude of an economic enterprise so great that financing would be impossible without Government aid in some form or other. The part of the country referred to is the heavily populated section in the northeast of the United States. To simplify an examination of the situation, let us take the potential marketing areas within range to the north and east of the three pipelines: 1. Tennessee Gas Transmission Co. as it enters Erie County, New York state. 2. Texas Eastern Transmission Corporation just before the tap that supplies the general Philadelphia area. 3. Transcontinental G& Pipe Line Corporation as it enters the state of New Jersey The sources of gas for these three pipelines are in Texas and Louisiana. The ultimate maximum combined capacity of the three lines at the points stated is approximately 1,200,000,000 cu ft per 24 hr at the maximum load factor probable of attainment in normal operation. The areas supplied by the three lines north and east of the points stated, or assumed as eventual markets, are: 1. Central New York state, from Buffalo to Albany (both inclusive).

Jan 1, 1953