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By Kenneth M. Ritchie

Mineral wool is a term applied to man-made fibers of silicate glass with useful properties resulting from their fibrous nature. In contrast with crystalline fibrous minerals such as asbestos, mineral wool fibers are amorphous, solid filaments produced by drawing from molten liquid and subsequent cooling. Chemically they are silicate glass with varying percentages of metallic oxides, especially those of aluminum, calcium, magnesium, iron, and in glass wool, sodium, potassium and boron. Other elements such as manganese, titanium, sulfur, etc., result from their presence in the raw materials used and are not purposely added. In the United States, mineral wool is a generic term and may be applied to rock, slag or glass wool. In Europe, glass silk and silicate cotton are products in the same category, but the term mineral wool is less commonly used. Current usage is to ignore the actual source and to differentiate products on a composition basis; thus rock and slag wools have about 35-45 pct of silica, while glass wool has 54 to 60 pct. Much mineral wool of slag origin is called "rock wool," and this practice is increasing, although wool made of slag from lead or copper refining is often referred to as "lead slag wool." Its greenish-gray to greenish-black dark color, due to 5-25 pct Fe (reported as FeO), distinguishes it from "white" wools made from iron, blast furnace slag containing only 1-2 pct FeO or Fe203. Most mineral wool is used for thermal insulation against heat and cold; sound absorption and isolation are probably the next most important uses. Both its thermal and acoustic values result primarily from the physical structure of the heterogeneous mixture of fibers and air which is the form in which the fibers are first obtained and handled. For this reason, within fairly wide limits, differences in chemical composition are relatively unimportant, and for most conventional applications all types are competitive in properties and value. Mineral wool intended for extreme conditions of high temperature, acid resistance and special purposes must have a chemical composition which will insure the desired properties. This may differ greatly from that of ordinary wools; for example one product approximately 98 pct Si02 and another consisting of 50 pct A1203 and 50 pct Si02 are produced and sold for high temperature service up to 2000°F or more. These are considerably more expensive to manufacture and their cost limits their use. Historical The manufacture of mineral wool consists fundamentally of a process which subjects molten material to shear and/or tensile forces that draw them into fibers. The liquids are cooled at a rate which solidifies them quickly. As a solid glass they are technically super-cooled liquids since they have no true melting point. The drawing out of glass into thin rods, filaments and tubes was known from very early times, and present day continuous production of glass filament for textiles was evolved gradually by adapting hand methods to automatic machinery. Rock and slag wool manufacture had a somewhat different development. Early explorers reported finding filamentous material

Jan 1, 1960

By T. D. Murphy

This chapter deals with those types of silica raw materials that have been segregated and refined by natural processes into nearly monomineralic deposits and hence, by virtue of their high degree of purity, have become the sources of commodities having special and somewhat restricted commercial uses. In some instances, these raw materials occur in nature as unconsolidated quartzose sand or gravel and can be exploited and used with very little preparation and expense. More often, they occur as sandstone, conglomerate, quartzite, quartz mica schist, or massive igneous quartz which must be crushed, washed, screened, and sometimes chemically treated before commodities of suitable compositional and textural characteristics can be successfully prepared. The occurrence and distribution of silica raw materials is summarized and an effort has been made to bring commodity definitions, critical properties, and specifications up to date. Presentation of mining and processing methods is considered beyond the scope of this article; they are, for the most part, conventional and well known. New production techniques are currently reported in the trade journals and are later adequately described in technical publications as promptly as competitive restrictions allow. Discussion on Basis of Use ABRASIVE USES Industrial silica used for abrasive purposes falls into three main categories: (a) blasting sand; (b) glass-grinding sand; and (c) stone-sawing and rubbing sand. Blasting sand is a sound closely-sized quartz sand which, when propelled at high velocity by air, water, or controlled centrifugal force, is effective for such uses as cleaning metal castings, removing paint and rust, or renovating stone veneer. It is commonly referred to as Sand Blast sand. Multicycle quartz sand is an efficient blasting agent by merit of its survival characteristics which are soundness, toughness, and hardness. Steel grit and shot have supplanted it to a large extent but owing to their higher cost and tendency toward deterioration in storage, are still not universally used. It is conceded that angularity promotes faster cutting but this is offset by a higher loss in fines. The peening action of a rounded grain is a desirable feature in achieving a satin finish for certain light metal castings but a subangular grain is unsurpassed for fast heavy cutting. Specifications are chiefly based on size frequency distribution but it is mandatory that the grain be free of adhering clay or irony coatings. Material that dusts upon handling will not be tolerated. There is no uniform trade designation for the many blasting sand grades. Most producers sell on the basis of numbered grades; that is, No. 1, No. 2 and so on, this generally connoting fine to coarser grades. Designation of grade by the two sieve sizes between which most of the material lies, is practiced in some areas. Thus, in a No. 1220 grade, 98 pct of the material passes a 12 mesh sieve and is retained on a 20 mesh sieve. Blasting sand specifications vary according to use. Coarse grades range from 4 mesh to 12 mesh, medium grades range from 12 mesh to 30 mesh, finer grades may range from 20 mesh to 100 mesh or finer. Specifications generally call for narrow limits of gradation, requiring precise sizing methods. The fact that most blasting sands are retained

Jan 1, 1960

By N. Albon, J. F. Miller, R. W. Coutant

The deposition of nickel from nickel carbonyl onto amorphous substrates has been studied, with attention being paid to the specific effects of the physical and chemical nature of the substrate and to the effect of oxygen on the crystal morphology. With substrates having microscratches or etch lines, nu-cleation was observed to occur preferentially at these surface features. Flame polishing of the substrate surfaces was found to remove any regularity in preferred nucleation sites. Nucleation was observed to occur less readily on substrates having relatively low surface energies, e.g., Teflon and carbon, than on materials having relatively high surface energies such as fused silica. At low oxygen concentrations [Ni(CO)4/O2 > 54 x 1031, apparently pure and well-formed nickel crystals were observed to nucleate and grow irrespective of the presence of oxygen. At higher concentrations of oxygen, a secondary growth process, dependent upon oxygen concentration and resulting in a gradual change in crystal morphology, was observed. It is concluded that the influence of oxygen on the nucleation and growth of nickel is determined by the relative kinetics of the various possible reactions, and that under the experimental conditions employed the 0-Ni interaction occurs at some nucleation or prenuclea-tion stage. THE purpose of the research on crystal nucleation in chemical vapor deposition as described in this paper has been twofold: 1) to examine some effects arising from the use of amorphous substrates, and 2) to study the specific effects of oxygen on the nucleation and growth of nickel in a nickel carbonyl-carbon monoxide system. The nickel-nickel carbonyl system was chosen for study for several reasons: 1) nickel films are of potential interest in electronic technology, and 2) the deposition can be carried out at moderate temperatures, thus making possible detailed study of the processes occurring and the use of a variety of substrate materials (including some which melt at relatively low temperatures). Fairly well-characterized chemical kinetics and a broad background of information are available on the py-rolysis reactions and on the mechanisms of Ni-O interactions. NUCLEATION AND GROWTH THEORY The theoretical background for the analysis of nucleation and growth by vapor deposition for a one-component system (physical vapor deposition) and the problems encountered therein have been reviewed by Hirth and pound.' More recently Mande12 has indicated the difficulties of applying such theory to chemical systems. One of the major problems involved is the possible multiplicity of chemical reactions and deposition routes. For example, those reactions which are probably of significance in a discussion of the pyrolytic deposition of nickel from nickel carbonyl under the conditions of the present experimental work are illustrated in Fig. 1. As is true with most cases of chemical deposition, many of the quantitative data necessary for a complete analysis of the system are either not available or not directly measurable. However, with the present system, sufficient data are available for a discussion of nucleation and growth on a qualitative basis. Classically, the rate of nucleation of a monatomic species being deposited from a vapor phase is given by

Jan 1, 1965

By R. P. Dolan, W. M. Shedd, B. L. Buchanan

Analytical expressions are derived from empirical data relating the basic physical device parameters to the radiation dose. To put in perspective and justify the approach taken, the overall problem and methods of attempted solution of radiation damage to transistors in a missile or satellite environment is briefly examined. The main emphasis is on a new criteria for neutron radiation hardness and the device design implications resulting from using this criteria. Contrary to other derived criteria, the derived bipolar hardness relation depends mainly on the initial lifetime rather than the base transit time. It is shown, that contrary to previously accepted beliefs, the inherent attainable radiation tolerance of JFET's is at least a factor of ten greater than the radiation tolerance ofbipolars. Experimental results on JFET's designed for maximum neutron radiation tolerance are presented. The accuracy, utility, and range of possible validity of various published lifetime and carrier removal damage constants are discussed. It is well known that transistors are subject to damage due to radiation at much lower radiation levels than those which would cause structural damage to a missile or satellite. The three principal categories of radiation damage to transistors are displacement, ionization, and thermomechanical. The main cause of displacement damage is fast neutrons, and the main effects which permanently degrade transistor operation are minority carrier lifetime reduction and carrier removal. A second-order effect is mobility reduction. The main cause of ionization damage is gamma radiation which results in permanent effects due to charge build-up in the oxide and transient effects due to photo-current generation. The transient effects are usually handled by using circumvention techniques in the electronics system. The extent of the transistor degradation due to displacement and ionization damage depends strongly on the transistor type, whereas the extent of thermomechanical damage does not depend on the transistor type, but depends mainly on packaging and metallization which are common to all transistor types. The standard transistor types are categorized in Fig. 1 and typical cross-sections are shown in Fig. 2. The original reason for the designation of the two classes of transistors was that the unipolar operation depends on only one carrier (majority) and the bipolar operation depends on both minority and majority car- riers. The bipolar is then seriously degraded by minority carrier lifetime reduction, whereas the unipolar or field effect transistor is not. One of the two principle classes of field effect transistors, the junction field effect transistor (JFET), depends strongly on carrier removal. However, the insulated gate (MIS) is little affected by either carrier removal or lifetime changes, but is virtually eliminated as a radiation resistant device because of permanent charge build-up in the insulator caused by ionizing radiation. The bipolar and JFET suffer only minor effects due to charge build-up in the oxide passivation when compared1 to the MOS. This is because the active region of the MOS is adjacent to or part of the oxide layer. It is then the bipolar and JFET which are potentially resistant to permanent radiation damage. DERIVATION OF RADIATION TOLERANCE RELATIONS Criteria. The bipolar is by far the most widely used transistor type. The usual criteria for hardening bipo-

Jan 1, 1970

By George A. Roberts, Arthur H. Grobe

Tensile, hardness and density properties are presented for a new 18-8 stainless steel powder for the —50, —100, and —140 mesh cuts and also for a prepared blend containing 62 pct —325 mesh powder. The data were obtained for sintering temperatures of 2100° to 2350°F and for compacting pressures of 30 to 50 tons per sq in. A NEED has existed for a stainless steel powder of uniform composition from particle to particle, which could be readily molded and sintered, and which would yield moderate to high strength and ductility when processed into parts by standard powder metallurgy techniques. The literature reveals that previously available powders have been lacking in one or several of these desirable characteristics. Originally attempts to produce stainless steel powder by blending and diffusing elemental metal powders were unsuccessfu1.l A truly alloyed stainless steel powder reported by Dale in 1947 yielded reasonable mechanical properties but required an exceptionally high sintering temperature of 2400°F in pure dry hydrogen.' A later development reported in 1950 by Stern provided a stainless type powder of excellent molding properties' but this powder likewise required sintering at temperatures over 2350 °F and did not yield properties as high as those previously reported. The powder was not truly alloyed prior to sintering. A prealloyed stainless steel powder has been developed that is readily moldable at 30 to 50 tons per sq in., can be sintered at low temperatures (2100" to 2300°F), and which yields compacts with both high strength and ductility. The powder is prepared by the liquid disintegration method," direct from molten metal. Early attempts to make 18 pct Cr, 8 pct Ni stainless steel powder by this method did not produce a usable powder for pressing and sintering because of a preponderance of spherical particles with relatively high, surface oxide content. It was learned that silicon additions to iron alloys, powdered by this process, gave bright powder of low-oxide content and such additions were made to 18-8 stainless with similar results. An attendant change in particle shape occurred reducing the number of spheroids materially. The optimum composition which has been studied and is reported here contains approximately 2.5 pct Si. Silicon additions to stainless steel of the 18-8 type improve the resistance to high-temperature oxidation and promote the formation of ferrite. Corrosion resistance is, however, controlled by chromium content and even though ferrite may exist the corrosion resistance is not generally impaired.4 Experimental Procedure A detailed study of the 18-8, 2.5 pct Si powder has been made in accordance with the following outline: 1. Four blends a. — 50 mesh b. —100 mesh

Jan 1, 1952

By W. C. Krumbein

Geological problems are approached from a geometrical (space relations) viewpoint, a kinematical (time sequence) viewpoint, or a dynamical viewpoint. The first two require sound training in conventional geology and in field methods. The third approach requires a solid foundation of chemistry, physics, and mathematics. Modern training for geologists should include close integrltion of basic sciences with geological principles. Introduction Our knowledge of the earth has increased tremendously during the last half century. We know more about its surface configuration, the distribution of its natural resources, the proccssion of living forms that inhabited it in the past, the chemical composition of its oceans, the areal distribution of its surface rocks, the movements of its atmosphere, and so on. Not only do we know more facts about the earth, but we have a better understanding of the processes that take place on and within it, such as the nature of earthquakes, the thermodynamics of the atmosphere, the chemical equilibria involved in the formation of igneous rocks, the mechanics of stream flow, the dynamics of the earth's origin, and so on. Many sciences contributed to the sum total of this knowledge, including such established disciplines as geology, geography, physics, chemistry, astronomy, biology. Out of this accumulation of new knowledge grew also a group of new sciences, such as seismology, oceanography, meteorology, volcanology, hydrology. Collectively these latter are known as the geophysical and geochemical sciences, and to a large extent they began as branches of geology. Until the turn of the century, for example, the study of earthquakes (seismology) was a part of geology, although as early as 1846 Mallet, a physicist, had suggested that the subject could be investigated by elastic-wave theory. Comparatively little progress was made along these lines until the seismograph was developed near the turn of the century; since then, additional earthquake data have accurnul~ted rapidly, but more important, the interpretation of these data essentially has kept pace with their accumulation. In similar fashion, meteorology was generally considered a branch of geology as recently as one or two decades ago. Considerable progress had been made in such aspects as weather forecasting, but the science dates its recent rapid rise from the year 1911, when Bjerknes first applied the principles of dynamics to the analysis of air masses. The rapid development of such disciplines as oceanography, volcanology and hydrology was due in part to the application of principles of chemical equilibrium, of dynamics, and of thermodynamics to earth problems, by men who were essentially physicists or chemists by training. The last half century, therefore, and particularly the last two decades, saw the influx of numerous chemists and physicists into the realm of the earth sciences. In the meantime the main body of geology itself showed a marked growth, and

Jan 1, 1946

By C. J. Osborn

The temperature dependence of the free energies of formation of metallurgically important oxides, sulphides, chlorides, carbonates and sulphates is presented graphically, whereby the task of deriving practical metallurgical information is greatly simplified. The diagrams have been revised according to the latest available thermodynamic data. WHILE it is true that much careful investiga-tional work remains to be done, there are already available in the literature sufficient thermo-dynamic data to enable the metallurgist to predict with reasonable confidence the equilibrium conditions to be expected in most important, and potentially important, metallurgical reactions. In this connection, the careful, critical compilations of K. K. Kelley and his collaborators in numerous U. S. Bureau of Mines Bulletins are particularly valuable. However, the translation of reliable thermo-dynamic data into metallurgical language unfortunately involves lengthy manipulations of the cumbersome formulas which can be set up from heat of formation, entropy, and heat capacity data. Many years ago, Kelley20 predicted that thermo-dynamic calculations would be made in the future "with the aid of free energy, heat content, and entropy tables, rather than by means of the algebraic methods employed at present", and where such tables are available they greatly simplify the task of deriving practical metallurgical information. However, in addition to these tables, there are also available one or two reliable graphical presentations, particularly of free energy data, which may be used in the same way as the tables, but which have the added advantages that interpolation is never necessary, and that the behavior of different metals or compounds may be compared at a glance. Some years ago Professor Robert Lepsoe, Head of the Department of Metallurgy at Norways Institute of Technology (N.T.H.), began a compilation of curves showing the temperature dependence of the heat contents of the elements, and the heat contents and heats and free energies of formation of the common metallurgical compounds. With such a compilation, the thermal and free energy requirements of a reaction may be read from curves in a matter of seconds; and this statement applies not only to the formation of compounds from their elements, and to the reverse dissociation, but to any reaction involving substances whose thermodynamic properties are available. This follows from the fact that heats and free energies of formation are completely additive. For example, the free energy change associated with the chlorination of a metallic oxide at any temperature, T, is given by the free energy of formation of the chloride at temperature T minus that of the oxide also at T; both of these quantities may be read directly from curves of the type suggested above. Since this early, unpublished work of Lepsoe, both Ellingham7 and Richardson and Jeffes46 have

Jan 1, 1951

By W. C. Krumbein

Geological problems are approached from a geometrical (space relations) viewpoint, a kinematical (time sequence) viewpoint, or a dynamical viewpoint. The first two require sound training in conventional geology and in field methods. The third approach requires a solid foundation of chemistry, physics, and mathematics. Modern training for geologists should include close integrltion of basic sciences with geological principles. Introduction Our knowledge of the earth has increased tremendously during the last half century. We know more about its surface configuration, the distribution of its natural resources, the proccssion of living forms that inhabited it in the past, the chemical composition of its oceans, the areal distribution of its surface rocks, the movements of its atmosphere, and so on. Not only do we know more facts about the earth, but we have a better understanding of the processes that take place on and within it, such as the nature of earthquakes, the thermodynamics of the atmosphere, the chemical equilibria involved in the formation of igneous rocks, the mechanics of stream flow, the dynamics of the earth's origin, and so on. Many sciences contributed to the sum total of this knowledge, including such established disciplines as geology, geography, physics, chemistry, astronomy, biology. Out of this accumulation of new knowledge grew also a group of new sciences, such as seismology, oceanography, meteorology, volcanology, hydrology. Collectively these latter are known as the geophysical and geochemical sciences, and to a large extent they began as branches of geology. Until the turn of the century, for example, the study of earthquakes (seismology) was a part of geology, although as early as 1846 Mallet, a physicist, had suggested that the subject could be investigated by elastic-wave theory. Comparatively little progress was made along these lines until the seismograph was developed near the turn of the century; since then, additional earthquake data have accurnul~ted rapidly, but more important, the interpretation of these data essentially has kept pace with their accumulation. In similar fashion, meteorology was generally considered a branch of geology as recently as one or two decades ago. Considerable progress had been made in such aspects as weather forecasting, but the science dates its recent rapid rise from the year 1911, when Bjerknes first applied the principles of dynamics to the analysis of air masses. The rapid development of such disciplines as oceanography, volcanology and hydrology was due in part to the application of principles of chemical equilibrium, of dynamics, and of thermodynamics to earth problems, by men who were essentially physicists or chemists by training. The last half century, therefore, and particularly the last two decades, saw the influx of numerous chemists and physicists into the realm of the earth sciences. In the meantime the main body of geology itself showed a marked growth, and

Jan 1, 1946

By Frank S. McKenna, Myron A. Pugacz, Clarence E. Jackson

THE notched-bar impact test has proved worth while in certain applications as a test for control of the quality or the heat- . treatment of steel. In view of the serious thought that even so simple a test as the tensile test, has evoked during the past years, it is not surprising that the notched- bar impact test should have inspired much experimental work. The correlation of the great number of data has not been successful, although steady progress has been made toward a better understanding of this test. Progress has been made, especially, in the isolation of the effects of the many variables that control the results. The stress system imposed on a specimen with a notch is so complicated and un- predictable that no simple evaluation of the test has been possible. Because of this uncertainty, many engineers hesitate to use the notched-bar impact test, and this attitude may well continue until a better understanding of the effects of the variables in the test are available. Without doubt, any additional data that may be presented should be accompanied by as complete a description of the details of test as possible, so that it may be added to the general fund of information that is to serve as the basis for the theory of the notched-bar impact test. The many factors that may control the test results have been pointed out repeatedly. The importance of the effect of the type and dimensions of the specimen has been recognized. Most of the work reported by American investigators has been limited to small- size (Charpy) specimens tested as a simple beam; two types of notches (Fig. I) have been commonly used. Considerable data have also been presented by many investigators using a small specimen tested as a cantilever beam; this commonly being called the Izod test. Here, however, a shear component of stress makes the stress system even mare complex than that present in the simple beam type of test, hence a critical analysis is difficult. Much work has also been reported by investigators using the tension type of specimen. A second variable that must be con- trolled is the testing temperature. An indication that the tests were performed at room temperature is not sufficient, since in many steels a variation of a few degrees in the actual testing temperature may be sufficient to give an entirely different range of results. Other factors. such as the com- position and condition of the material being tested and the speed of test, should also be considered. Many investigators have contributed data and theoretical discussions on the problems encountered in notched-bar test-

Jan 1, 1944

By M. E. Fine, A. A. Hendrickson

The critical resolved shear stress and the strain rate dependence of the .flow stress are reported for Ag base A1 single crystals up to 6 at. pct A1 over a temperature ralzge of 4.1° to 470°K. At room temperature the solid solution strengthening is attributed brinciballv to an increase in the dislocation density on alloying. At 42°K the alloys are relatively stronger because the dislocations widen on alloying and are more difficult to cut. In a previous paper, the authors reported the characteristics of strain aging in Ag base A1 alloys.' The variation of the magnitude of the strain-aging yield drops on aging time, aluminum content, and testing temperature strongly indicated that the phenomenon is due to the Suzuki mechanism. In the present paper, the critical resolved shear stress (CRSS) and the strain rate dependence of the flow stress are reported for Ag base A1 single crystals as functions of testing temperature (4.2" to 470") and A1 content (0 to 6 at. pct). Observations on the substructure and measurements of the effect of crystal growth rate are also given. The experimental re- sults appear explainable considering that aluminum additions increase the dislocation density and dislocation width. EXPERIMENTAL METHOD The methods of specimen preparation and tensile testing were described previously.' Briefly, single crystals were grown from the melt in a vacuum (1 x lom5 mm Hg), shaped into tensile samples by a combination of abrading and acid etching, annealed at 850°C in a vacuum (1 x 10" mm &Z) for several days, and furnace cooled to 200'. The testing was done on a model TM Instron using friction grips and a strain rate of about 5 x 106 per sec unless otherwise noted. The various testing temperatures were obtained by immersing the specimens in the following media: 1) 4.2': liquid helium using the apparatus of G. Byrne;' 2) 77°K: liquid nitrogen; 3) 200"K: dry ice and acetone; 4) 415' K: ethylene glycol; 5) 460' \ to 480' : molten Stanalax. In the determination of the CRSS above 296' K, a ratio method was used; the crystals were strained initially at the higher temperature, 0.1 pct shear strain, and then tested at 296' . The ratio of the flow stress between the two temperatures was then multiplied by the average CRSS at 296' K to obtain the value of the CRSS at the high temperature. (The test at 296' showed a yield point resulting from strain aging; the flow stress at 296' K was taken as the lower yield stress.) The ratio method, we believe, is more accurate than using different crystals since

Jan 1, 1962

COLLECTIVE bargaining, hereto-fore loudly proclaimed as one of the stout timbers of the Republic, has passed from the picture. The coup de gr[a]ce was struck by the President of the United States when he ignored his vested legal prerogative and seized the steel industry by the dubious authority of, his "inherent powers." Autocratic judgment by a single official replaced arbitration by the steel industry and labor union. This is the outcome of a battle which has been bitterly waged for months in the hazy atmosphere created by well oiled propaganda machines. Prior to government intervention, there was no clear picture of the issues at stake. All parties concerned marshalled their accountants to conjure up figures proving their respective contentions. The results were fed into public relations departments for embellishment and dissemination. Thus, the public was asked to believe on one hand, that the steel worker, who is second only to the coal miner in hourly wages, was entitled to an increase in pay and other benefits. Nothing was said about the effect-of such an increase on the national economy. Industry in turn pointed to declining profits after taxes, but failed to mention the more than a billion dollars spent on plant expansion, in addition to the payment of substantial dividends for 1951. With the intervention of the administration, the immediate issue became clear to freedom-loving Americans. Is the executive branch of the government above the law, or is it supposed to uphold and carry out the .laws of Congress? The present administration forgot that it is a servant of the public and has become despotic. The American people must obliterate this dangerous precedent which has been set by the administration or accept the. ominous consequences of submission. Fortunately, the strongest weapon of the citizen-the ballot -still remains. When democratic procedure is restored, stabilization of the economy will continue to challenge us. This is the main public stake in the steel controversy. Only a solution based on bed-rock democracy will work. If the emergency is real, and we must assume that it is, this is the time for sacrifice. Industry and labor must meet without rancor to resolve wage contracts through collective bargaining. The government role, under emergency conditions, must be to objectively maintain wage, and price ceilings in the interest of stabilization. Political expediency cannot be permitted to' influence these controls. Politics and not the public weal have been the guide lines for too long. We are at the cross roads. By all sober judgment, this is the time for Americans to take a militant interest in their government today. Tomorrow will be too late.

Jan 1, 1952

Theoretically mobile primary crushers at the mine working face can be considered the ideal comminution system. A crusher which follows the ore can reduce materials handling costs because it eliminates about one ton of truck deadweight per ton of ore hauled to the crusher. It also eliminates the backhaul of this same deadweight ton. Development of mobile primary crushers has centered in Germany where many soft iron ore and limestone deposits are flat-lying and thus readily adaptable to the use of shiftable conveyors which easily followed the working face. These ores were easily crushed in impact- type mills which had extremely large receiving openings and therefore large reduction ratios. The feeding of such a unit was done with a front-end loader which dumped its load to an inclined apron feeder, which in turn fed the impactor. Under the crusher was an inclined conveyor which transferred the crushed ore to a belt wagon for delivery to the shiftable overland conveyor. Low headroom overhead eccentric single-toggle jaw crushers and short-shaft gyratories were also used on these units, which generally travelled on tracks. While these early mobile primary crushers were versatile and served their purpose, they generally suffered from low capacities. Manufacturers have quickly responded with larger crusher, feeders, and moveable supports, however; and today mobile crusher s have capacities of up to 1500 metric tons per hour, a figure comparable to the capacity of some 54 in. by 74 in. gyratories. An example of a quarry portable crushing plant is at the Bath cement plant of Canada Cement Lafarge, Limited. Two 12 cu yd front-end loaders are digging the stone and hauling it to the portable crushing plant which feeds a field conveyor system. The crushing plant is moved and the field conveyors extended whenever the length of the haul exceeds 300 ft. At the crushing plant, the loaders discharge the stone onto a pan feeder which feeds into the hopper of a Weserhutte-Hazemag compound crusher which combines primary and secondary rotors in the same housing. These are driven at 1200 rpm by 800 hp and 1,000 hp motors (600 and 750 kw). The maximum 3 ft feed (914 mm) is reduced to 3/4 in. (19 mm) at 800 tph. The Weserhutte steered walking mechanism, operated by hydraulic cylinders, takes five -foot strides. Another example is at Alcoa of Australia's operation at Huntley in Western Australia. At the mine face, front-end loaders load 50 mt rear-dump trucks that transport the bauxite ore to the mobile crusher which follows the mine operation. The crusher can turn 360° within its own length, walk at a speed of 34. 5 ft per minute (10.5 m per

Jan 1, 1978

JOHN W. BELL (communication to the Secretary*).-I have to thank Mr. Merrill not only for his very kind remarks, but for the weight of his implied opinion that the work accomplished probably has an important practical aspect. I think there is a distinct although unuttered impression among engineers, that it will be time enough for them to begin to take an interest in the law of crushing when it emerges from the cloud of violent and even vituperative controversy that has hovered over it during the last 6 or 7 years. I have a very confident feeling that as the result of the work done by Mr. Gates, by me and by Messrs. Mitchell, Baily and Cockfield, who so loyally helped me to obtain the necessary data, at least the practical law of crushing has emerged; that it is ready and available for use by our fellow engineers, and that it will help them to unravel a number of the many practical problems they are con¬stantly confronted with. In regard to Mr. Gates' discussion, I would indeed like to believe that McGill could claim, as a minor achievement, the credit which Mr. Gates so generously bestows of having established the "law" of crushing. I think that more work would be required to establish this claim in the, strict sense of the word, as there is a fairly large gap between the coarse and fine crushing results. I am not worried about that gap, because the reason for it is quite clear to me; at the same time I-think it will be well to bridge it by a series of tests, and I am bound to admit that the testing machine is the most promising machine right at hand to work with, although whether the minute amounts of power required to crush small quantities of rock can be so accurately integrated as to insure high accuracy in the final result is still a question in my mind. If we had an Amsler-Laffon machine I would certainly try it. Mr. Gates' remarks about choke crushing are extremely interesting. He compels me to wonder, too. It is a new and probably a very important factor to be considered in this connection. I am in perfect accord with Mr. Gates about the desirability of the determination of crushing constants, because when this is accomplished the efficiencies (not relative mechanical, but real efficiencies) of different types of rock-crushing plants in any part of the world will then be comparable. For this reason it would, seem desirable that the American Institute Committee should not only consider ways and means for accom-

Jan 6, 1917

By B. G. Hurd

A liquid-Freon permeameter suitable for making routine permeability determinations on small plug samples is described. The instrument is characterized by simplicity of design and ease of operation, and can be assembled inexpensively from stock items of laboratory equipment. It combines the unique advantages of both liquid and gas permeam-eters while eliminating many undesirable features of both general classes of instruments. Precision and accuracy of the specific Freon permeability measurements compare favorably with results of conventional liquid and gas permeameters. INTRODUCTION The liquid-Freon permeameter described in this paper was designed and built for special investigations of the properties of petroleum reservoir rocks. However, its unique advantages over conventional gas and liquid permeameters make it eminently suitable for routine use in the core analysis of small plug samples. In general, gas permeameters are very popular because of their simplicity of design and ease of operation. However, apparent gas permeabilities are normally higher than true specific permeabilities unless special corrections for gas-slippage are applied. Since these corrections require two or more measurements at different internal gas pressures, much of the time advantage of the specific gas permeability measurements is lost. Liquid permeability measurements, on the other hand, require no slip correction, but liquid saturation of the sample is time-consuming and difficult to insure. Often, too, the saturating liquid must be extracted or dried from the plug before it can be used for another experiment. The liquid-Freon permeameter described herein retains the inherent accuracy of the liquid permeameter, while affording the speed and ease of operation of the gas permeameter. Freon-12 (dichlorodifluoromethane) is a haloge-nated hydrocarbon, immiscible in the liquid phase with water. It may be considered as an oil phase in laboratory fluid-flow studies. Like butane and propane, it is a gas at normal room temperatures and atmospheric pressure but can be liquefied at moderate pressures. Complete liquid saturation of a plug sample with any of these fluids can be easily achieved by condensing vapors in the sample and operating the permeameter at a pressure above the vapor pressure of the liquid. Freon-12 is superior to butane or propane for permeability measurements only in that it is relatively nontoxic and completely incombustible, and thus presents no fire or explosion hazard. Freon-12 is believed to be completely nonreactive with most petroleum-reservoir rock samples. It volatilizes immediately from a plug on depressurizing to leave a clean, dry sample suitable for subsequent experiments. Thus, the inherent risk of changing physical properties of rock samples by cleaning and drying operations between permeability measurement and subsequent experiments is eliminated. DESCRIPTION OF THE PERMEAMETER The design of the liquid Freon-permeameter is shown schematically in Fig. 1. Regulated nitrogen pressure caps are used both as a driving pressure

By L. J. Demer, W. W. Walker

AMONG several variables of the indentation hardness test is the effect of loading time on the measured hardness of a material. The most generally recommended duration of loading is 10sec.1-3 Although this short loading duration is undoubtedly satisfactory for harder metals, it is questionable that it is sufficient for very soft metals,4 or for certain plastics.5 The effect of duration of loading on the measured hardness of ionic crystals is largely unknown, although Onitsche and Mitsches found that the indentor (under a very low load) had not yet reached equilibrium after 60 sec in a variety of ionic crystals. To extend further the data of Onitsche and Mitsche, a systematic study was made of the effect of duration of loading for longer periods, up to 50,000 sec, on the 136 deg Dph of synthetic lithium fluoride. For comparison, less extensive tests were made on synthetic magnesium oxide and copper single crystals. The general procedure used was to indent a cleaved and polished (100) face of a lithium fluoride crystal using a Leitz Durimet microhardness tester. In certain cases, the indentor was so oriented as to align the diagonals of the 136 deg diamond pyramid indentation parallel to a (100) edge. In other cases the diagonal of the indentation was aligned at 45 deg to a (100) edge of the crystal. After indenting, the surface tested was etched in the acid etchant recommended by Gilman and Johnston.' This revealed the position of dislocation lines which intersected the surface tested. At these points of emergence were formed the usual sharp, pyramidal etch pits as shown in Fig. 1. The specific procedure used in studying duration of loading was as follows. The surface of the crystal was indented, and the load was left on the indentor for a predetermined time. This duration of loading was varied systematically from 1 to 50,000 sec. After the desired amount of time had elapsed, the indentor was removed from the crystal and the size of the resulting indentation was determined using a micrometer eyepiece. The surface was then etched to reveal the dislocation etch pit pattern around the indentation. Procedures used for lithium fluoride, magnesium oxide, and copper were similar. Preliminary studies revealed that, although an indentation was enlarged by increasing loading time, no corresponding changes occurred in the surface etch pit pattern. Since no evidence of dislocation movement was observed on the surface, it was assumed that the plastic deformation indicated by the indentor sinking into the surface was a result of dislocation movement inside the crystal. This movement was studied bf making a series of surface indentations in a crystal corresponding to various lengths of time, cleaving the crystal vertically through the indentations, etching the freshly

Jan 1, 1964

By H. L. Washburn, G. L. Judy

DURING recent years thermal drying of fine coal has increased at a tremendous rate, but very little discussion of the several excellent units has found its way into print. This is particularly true for operating and maintenance costs, and the operator who is faced with his first fine coal drying installation must depend chiefly on hearsay when trying to determine what his drying costs will be. This article presents the maintenance and operating costs for the seven drying units now installed in preparation plants of Pittsburgh Consolidation Coal Co. and lists other cost information that should be obtained before any particular drying unit is selected. Plant Description: The fine coal drying section of Plant A consists of four Flash driers operating on two furnaces equipped with spreader stokers. Plant B has one Flash drier operating (together with a screen-type coarse coal drier) on one furnace equipped with a spreader stoker. Plant C has two Cascade-type driers operating on a single furnace with a spreader stoker. Plant Costs: Tables I, 11, and III present the cost of operating these units as reported by the individ- ual plants. As can be seen, the labor rates vary, depending on the amount of overtime paid and the time interval the cost figures cover. There is considerable variation in thermal units used and in the value given to the thermal units at the particular mine. There is some difference in power costs at a given location and, finally, the power costs of conveyors leading to the drying plants were included in some cases. Maintenance supply costs are simply a tabulation of the cost of all supplies used on the driers, furnaces, and stokers. Depreciation is not included, and the tables omit items such as supervision, plant cleanup, oiling, general maintenance, taxes, and insurance. These tables in themselves do not offer a true comparison of costs. This information must be reduced to some common basis. But what is this common basis to be? A mine operator must calculate his overall mine and preparation plant costs in terms of tons of clean coal sold. Unit costs on pieces of equipment within a given plant are correctly calculated on the same basis. However, when unit costs are compared between one plant and another, some thought must be given to unit design. This reasoning is similar to the old argument concerning i solid bowl vs basket-type centrifuges—the units themselves are not directly comparable without their supporting equipment. So it is with thermal driers. Except in rare cases of low entering moisture i content, driers are sized on the basis of water that must be evaporated, while the wear each unit gets de-

Jan 1, 1958

By Howard S. Lee

In central Colorado is a great belt of intrusive porphyry nearly 100 miles long (160 km.), extending from the Clear Creek district on the north to Aspen on the south, which includes many of the well known mining camps of the state. Near the southern end of this belt, at Leadville, the occurrence of these intrusives is most marked, resulting in intensive mineralization and the formation of a great variety of large orebodies. During the past 40 years, Leadville has been a steady producer of gold, silver, lead, zinc, manganese, iron, and bismuth, in the forms of sulfide, carbonate and oxide ores. It is the purpose of this paper to discuss pyrite alone, which, under present economic conditions, is valuable chiefly for its sulfur contents. The ore-bearing formation of the Leadville district consists of two beds of limestone separated by a layer of quartzite. The upper limeatone is carbonaceous, and is known locally as the blue limestone. It varies in thickness from 50 to 300 ft. (15 to 91 m.). The lower limestone is Silurian, known locally as white limestone, and is about the same thickness as the upper bed. Underneath the Silurian limestone is a layer of Cambrian quartzite from 100 to 250 ft. (30 to 76 m.) thick resting on Archean granite, which forms the limit of ore deposition. As a rule, there is a sheet of white porphyry above the upper, or blue limestone; a sheet of gray porphyry is associated with the blue limestone, either in or below it, but the porphyries are not so regular as the quartzites and limestones and are not always found in their expected positions. Throughout the district there is an elaborate system of faults and intrusive porphyry dikes, which have an important bearing on ore deposits. The writer has seen two or three orebodies which were not closely associated with either a fault or a porphyry dike, but if the minor fractures and water courses are considered as part of the fault system it is safe to say that all orebodies are directly traceable to one or both of these causes. The distribution of pyrite in the Leadville district is quite general; but, eliminating the smaller bodies and those containing prohibitive quantities of zinc or lead, and considering only the larger deposits commercially valuable for their sulfur, we find the chief pyritic ore-bodies extending in a zone approximately 6000 ft. (1828 m.) long and several hundred feet wide, from the Yak and Moyer, on the south; through the Louisville, Greenback, Mahala, Adams, and Wolftone, on Carbonate Hill; across Yankee Hill, and into the Quadrilateral, Denver City, and Tip Top, on Fryer Hill.

Jan 1, 1920

We the undersigned, being all persons of full age and citizens of the United States and a majority residents of the State of New York, desiring to form a corporation pursuant to the provisions of the Membership Corporations Law for the purpose of incorporating, as provided in Section 5 of Article I. of said law, the existing unincorporated association known as American Institute of Mining and Metallurgical Engineers, Incorporated, do hereby make, acknowledge and file this Certificate for that purpose, and do Certify as follows: I. That the American Institute of Mining Engineers is an unincorporated association organized and existing with the object of promoting the arts and sciences, connected with the economic production of the useful minerals and metals and the welfare of those employed in these industries by means of meetings for social intercourse and the reading and discussion of professional papers, and to circulate by means of publications among its members and associates the information thus obtained. II. That the persons duly appointed or designated to manage the affairs of said association are designated by the rules thereof Members of its Council; that the undersigned are all members of said Council as the same was constituted on the 29th day of December, 1904. III. That on said last-mentioned date a regularly called meeting of said association was held at its office in the Borough of Manhattan, City of New York; that thirty days before such meeting notice of the intention to incorporate said association was given by mail to each member thereof whose residence or post-office address is known; that at said meeting the following resolutions were offered, seconded and duly adopted by the unanimous vote of all its members then present, to wit: "Resolved, That it is the sense of the members and associates of the American Institute of Mining Engineers in general meeting assembled that it is desirable and necessary for the well being of said association and its members and for the furtherance of the objects for which the same has been formed, that said association incorporate under the Membership Corporations Law of the State of New York; "And Further Resolved, That the Members of the Council of this Association, or a majority thereof, be and they hereby are authorized, in accordance with the provisions of Section 5 of Article I. of the Membership Corporations Law, to incorporate this association for the same purposes for which it has been organized and conducted, in the manner provided in Article II. of said law;, "And Further Resolved, That the name of said corporation as hereby adopted by this meeting shall be American Institute of Mining Engineers; "And Further Resolved, That the said incorporators shall be named in the Certifi¬cate of Incorporation as directors of such corporation until its first annual meeting,

Jan 1, 1940

By D. B. Carson, D. L. Katz

Natural gases under pressure form crystalline hydrates with water. Experimental data are reported on four-phase equilibrium for the methane-propane-water, methanc-pentane-water, and methane-hexane-water systems. Temperatures and pressures for equilibrium between gas, water-rich liquid, hydrocarbon-rich liquid, and hydrate were measured, as well as the percentages of methane and propane in the hydrate. The data indicate that natural gas hydrate behaves as a solid solution and that pentanes and heavier hydrocarbons do not enter into the solid phase. Vapor-solid equilibrium constants are presented that permit the approximation of the conditions for hydrate formation, from the composition of a gas. Introduction Natural gas hydrates have been the object of considerable research in recent years, because of the trouble they have caused in the natural-gas and natural-gasoline industries. Natural gas hydrates are white crystalline compounds of water and gas, which, under pressure, exist at temperatures considerably above the freezing point of water. Because of the relatively high temperatures at which the hydrates exist, they become a nuisance in high-pressure gas operations where water is present, since their formation causes partial or complete plugging of valves and pipes. From a practical standpoint, the trouble incident to hydrate formation has been solved by dehydration of the gas before it enters the plant or pipe line, or by other remedial measures. Extensive work on gas hydrates in the latter part of the nineteenth century, by Villardl and others, gave data on methane hydrate and on ethane hydrate. Schroeder summarized these theoretical studies2 Hammerschmidt3 introduced the information on gas hydrates to the gas industry and Dcaton and Frost4-6 gathered a considerable number of data on the behavior of natural gas hydrates. Recent papers7,8 have extended both the data and the theory of these hydrates. At present, data are available on tem-peraturcs and pressures of hydrate forma. tion for pure methane, ethane, propane, n-butane, methane-ethane mixtures, meth-ane-propane mixtures, methane-butane mixtures, and some Is natural gases, all- in the Presence of excess water. However, up to the Present time no method has been available for predicting the temperature at given pressures or the pressure at given at at which natural gases will form hydrates if hydrates with water. 'This Paper Presents data on the methane-propane-water, methane-pentane-water and methane-hex-""e water systems in four phases, one of which is the hydrate. he application of the phase rule to the methane-~ro~ane-water data Proves that hydrates behave as solid solutions. The data of this paper and those in the literature were used to develop vapor-solid. equilibrium constants,8 which permit prediction of conditions of hydrate formation from the analysis of a natural gas.

Jan 1, 1942

By A. G. H. Anderson, A. W. Kingsbury

Silicon bronzes containing ken are used to a considerable extent in industry, under the trade name of P.M.G. alloys. Various classes of wrought alloys fall in the composition range 1.5 to 3.5 per cent silicon, and 0.5 to 2.5 per cent iron. Castings may contain as much as 6 per cent silicon and 3 per cent iron at present. The constitutional diagrams of these alloys are thus of considerable practical importance. Copper-silicon-binary alloys have been thoroughly investigated by a number of workers, the latest reports being those of C. S. Smith1 and of A. G. H. Andersen.2 Although much work has been done on iron-copper alloys,3 recorded investigations on the copper-rich copper-iron binary constitutional diagram are not numerous. Tammann and Oelsen4 etermined the solubility limits of iron in copper by means of magnetic measurements, and found that the solubility of iron in copper amounts to a fraction of one per cent at 400°C., increasing slowly to one per cent at 800°C. From 800°C., the solubility increases rapidly and attains 4 per cent at iioo°C. Hanson and Ford,5 using electrical resistivity measurements and the microscope, determined a somewhat different solubility limit. of earlier X-ray works on the copper-iron system, very little has been published. The work by Bradley and Goldschmidt6 on copper-iron-aluminum alloys includes some information on the copper-iron binary. These investigators conclude that substitution of iron in the copper lattice decreases the spacings, which is contrary to the evidence of the present work. Hanson and West? have investigated the ternary alloys of copper with iron and silicon. Although their diagrams are valuable contributions to the understanding of these alloys, they did not recognize the kappa phase,l,2,7,8 and their diagrams do not everywhere conform to the phase rule. The present work contains a check by means of X-rays of the solid solubility limit of iron in copper, and an X-ray investigation of the ternary-phase diagram, which, owing to present conditions, it became necessary to curtail considerably. Preparation of Samples Castings weighing about 75 grams were melted under vacuum. The charges were made up of ingot iron, copper cathodes from Laurel Hill, and refined silicon supplied by the Electrometallurgical Co. Alundum crucibles were generally used. The exceptions were alloys 77 and 78, which were melted in graphite crucibles. The ingots were annealed at 800°C. for one week, then samples were cut for chemical analysis. Longitudinal sections of the binary alloy ingots were hammered into plates 1/8 in. thick. Wherever possible, these plates were homogenized at temperatures ensuring

Jan 1, 1943