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By G. I. Voiloshnikov, V. E. Dementyev

Wide use of adsorption methods for metal recovery is one of the most important achievements of gold metallurgy of the last decades. Anion exchange resins or activated carbons may be used as adsorbents. This paper presents a brief overview of IRGIREDMET effotts on development, testing and implementation of techno­logical flowsheets using both adsorbent types and attempt to compare their technological properties. IRGIREDMET Institute was founded in 1871 as a laboratory for gold smelting and gold ore testing. In 1930 it obtained the status of the Research Institute. IRGIREDMET functioned as leading research center for gold mining industry in the former Soviet Union. At present it is the Open Joint Stock Company dealing with all s01t of research and design works for gold min­ing (ranging from geology to gold refinery). IRGIREDMET started development of ion exchange technol­ogy in 19641• The first stage of work (1964-1970) including development of principle flowsheet of RIP process was carried out jointly with the Moscow VNIIKHT Institute (All-Russian Scientific Research Institute of Chemical Technology)2• The flowsheet of RIP process is presented in Fig. I and includes the following basic operations: gold adsorption from pulp; washing of loaded resin; acid treatment; thiourea adsorp­tion; gold elution by acid thiourea solution; resin washing to remove thiourea; alkaline treatment of resin; resin washing and gold recovery from eluates by electrowinning. The technology developed and equipment used were tested for treatment of clayey ore of Kuranakh deposit at a pilot plant of the Lebedinsky gold complex ("Aldanzoloto" company, Yakutia, Russia). The pilot plant throughput was 200 t/day. At the same time IRGIREDMET conducted the tests on ion exchange technology for ore and concentration products of oper­ating gold plants and for ores of new deposits. Laboratory and pilot plant tests were done and developed initial data and process design criteria for designing of 15 plans of the former Soviet Union. In the course of this work a great number of newly synthe­sized anion exchangers including strong and weak base resins was studied, the peculiarities of anion exchange resins using two different raw material types ( ores and concentrates includ­ing clayey, carbonaceous, silver bearing, arsenic, antimony and base metals bearing products); some theoretical regularities of adsorption process were investigated; the technology of two stage adsorption of gold and silver from silver gold ore, improved flowsheet for gold elution and resin regeneration, design of adsorption equipment including pulsation columns, design of electrowinning cells were developed; conditioning technology for pulp with complex ion composition prior to gold and silver adsorption was developed, etc.3·8• IRGIREDMET specialists took part in commissioning of practically all the plants in the former Soviet Union using RIP and RIL process including Lebedinsky, Kuranakh, Sovetsky, Karamken, Matrosov's plant and Mnogovershinny plants. Due to this works RIP process became standard technology for Russia and the CIS.

Jan 1, 1998

By Alexey P. Tatarinov

Under modern economic conditions in Russia, gold heap leaching is the most effective way of investing into gold-mining industry. Gold is recoverable from small-size deposits, low-grade ores from oxidation zone, cut-off grades, and overburden rocks using heap leaching. This technology is cost-effective and allows a saleable metal to be obtained within the first year of operation. The investments for heap leaching are lower than those of for a traditional plant technology. Production cost per one gram of Au is 5-7 times lower than that of during a plant flow sheet. A seasonal development of mines can be possible. With reference to this, heap leaching resembles the technology of placer deposits development. One of the major advantages of heap leaching is the form of the product. Gold can be obtained as dissolved in a clarified PLS, which allows the further quick treatment. The amenability of ores to heap leaching depends on their mineralogical composition. Oxidized porous ores with a good access of a lixiviant to valuable particles can be treated without pre-crushing. Clayish minerals are often found in oxidized ores with free gold. In order to build ground for heap, several major methods combined with various pad materials are used. These methods have been used at many plants and are reliable. The development of heap leaching technology for gold ores for the deposits from Yakutia, Zabaikalsky region, Primorye region, Uzbekistan, Tadjikistan, and Kazakhstan began in the 70s. However, it has been commercially used only since 1990. The first heap leach plants were built and commissioned in the USSR in 1991 at Vassilkovsloye deposit (Kazakhstan) and at Maiskoye deposit in Russia in 1994. Pilot plant testing was conducted in 1996 using ores from Kuranakh ore field, deposits Phiskulturnaya-Kholodnaya and Lopukhovskoye from the Aldan region. After the first successful commissioning of heap leaching plant in Russia, this technology has been commercially applied for deposits. Every year 1-2 heap-leaching plants were commissioned. More than 30 heap-leaching plants have been commissioned both in Russia and in the former Soviet Union using technologies developed by IRGIREDMET. Keywords: cyanide leaching, heap leaching, ore, percolation, solutions, lime technology

Sep 1, 2012

By Rainer W. Kaiser

High wear resistant HSS rolls are being successfully used in the first stands of HSM finishing trains since the early 1990´s. The strong demand of mill administrators to make them applicable also in the last stands of the finishing rolling mill is a major influence factor of R&D efforts at respective roll suppliers. Looking back to the successful replacement of ICDP and HiCr rolls by more economic HSS rolls in F1-4 in regard to the TCO, rolling mill managers wish to repeat such scale gain also at F5-7 stands. Actually used enhanced ICDP rolls wear faster, being the HSM stoppage factor. F1-4 HSS rolls can be used for example 3 times longer. There is an obstacle to be overcome by roll suppliers and end users to replace F5-7 rolls by HSS rolls. Stick and crack resistance properties of HSS need to be improved. As a worldwide known leading producer of cast rolls for steel mills since 1820, the traditional German family owned foundry and machine shop IRLE, existing since 1693, accepted to face also this additional challenge. IRLE´s long year experience and prior researches have shown possible development directions to improve mentioned stick and crack resistance properties of its HSS grade, called SST. A new material of the HSS family is in the development pipe line and is discussed: SST/G. Choice criteria of the development direction, steps to control and guarantee respective sections of an industrial scale production as well as observations and results are described.

Jul 30, 2018

By John Sullivan

Resources for Freedom, a report by the President's Materials Policy Commission, commonly termed either the Paley report, after its chairman, or the PMPC report, was issued in June 1952. The data collecting and assembly work for its preparation were done in 1951. The statistical base in most cases was 1950. It reviewed our economy and predicted what it will be in 1975.* The bases for the predictions were given. Consideration was given not only to statistical data and trends but also to technological changes taking place and likely to take place in the ensuing 25 years that will affect our economy. The supply of raw materials was studied and predictions made as to the availability of supply and the sources in 1975. One of the industries covered was iron and steel. For the most part the report did not attempt to provide a curve showing annual growth for any industry or commodity. It contrasted 1950 with the probable status in 1975. Interpolation between these dates is difficult and the Commission did not intend that it be used for short interim intervals. It is possible in 1958 to show the actual changes from 1950. The magnitude of the changes illustrates the agreement with some interpolation of the Paley report. Statistical comparisons can be general only because the Commission did not postulate a linear change. A study of the iron and steel industry will show if the general predictions have been realized or if gross errors were made. This paper is concerned with such an analysis. It is concerned with the production and consumption of crude, not fabricated products. It attempts to bring various facets of technical and statistical information on the industry up to date.

Jan 8, 1959

By A. P. Paiva

The solvent extraction properties exhibited by some /V,N'-tetrasubstituted malonamides to efficiently and selectively recover iron(III) from concentrated chloride leaching solutions can be found in the recent literature. The iron(III) extractive chemistry exhibited by some of these derivatives is revisited, in order to compare their chemistry with that shown by a few of the new malonamide compounds. The generally good extraction efficiency towards Fe(III), from >4 M hydrochloric acid solutions, and the relative ease of Fe(III) stripping by distilled water are remarkable findings that are confirmed for the malonamide derivatives described in this work. Furthermore, additional data regarding their selectivity towards Fe(III) extraction over several base metal ions and their behavior when subjected to successive Fe(III) extraction-stripping tests are also presented and discussed.

Jan 1, 2006

By H. M. Friede

Iron Age metal working in the Magaliesberg area by H. M. FRIEDE, Ph.D. (Visitor) Evidence of smelting and metal working in the Magaliesberg comes mainly from three sites: Broederstroom (Pretoria District). Uitkomst Cave (Krugersdorp District), and Olifantspoort/Olifantshoek \Rustenburg District). The analyses of copper ores found at or near these sites are reported. as are the analyses of twenty-six samples of slag from the Magaliesberg area and other sites in the Transvaal. Iron implements and copper ornaments found at the Magaliesberg sites are described. and the analyses of some of these specimens are reported and discussed. A metallographic report on two iron objects from Broederstroom points to similarities in the smelting and forging techniques that were practised in the Transvaal and Nigeria during the Early Iron Age.

Jan 6, 1977

By John B. Pearse

IN view of the great importance of accurate knowledge respecting the chemistry of iron and steel, as related to their physical properties, I come before you with a paper showing the great mass of work which has been heretofore done on the subject. I have tabulated the more important data I bring at this time, so as to draw out the results clearly. This information is accessible to all who will seek for it. I have made it the basis of my own practice throughout, and such knowledge is undoubtedly the only foundation, for the successful practice of metallurgy. As is well known the ordnance corps of our army, after 1841, made exhaustive experiments on the properties of cast-iron. The investigations were undertaken in order to obtain necessary information on the reorganization of the corps. I wish to call your attention to the results obtained by a comparison of the chemical and physical properties of cast-iron for guns, to describe certain characteristic peculiarities of steel, and to give a brief history of the chemical work relating to carbon in iron. The Reports on Experiments on the Strength and other Properties of Metals for Cannon, published by H. Carey Baird, Philadelphia,

Jan 1, 1876

Selected bibliographies of the Iron Resources of the World and the Coal Resources of the World have' been prepared by the Engineering Societies Library for the National Research Council from the most prominent. American, English and foreign books and periodicals. The bibliograpies are intended as a guide to the literature giving economic

Jan 5, 1919

By R. A. Parra, Fuentes, C. Godoy, L. E. Arias, C. A. Toro, M. Marin, E. Balladares, V. Parra, G. Reyes, S. N. Torres, D. Sbarbaro

In this paper, we report on the detection of spectral molecular emission of iron oxide (FeO) and copper oxide (CuxO) emitted by reactions occurring in a laboratory scale flash smelting process of pyrite (FeS2) as well as copper concentrate. The novelty of the technique is that, the molecular spectral emission sensing is achieved by using a low spectral resolution and low sensitive radiometer, enhanced with signal processing and matrix factorization techniques. The method was validated using a highly sensitive spectrometer, with a high spectral resolution; achieving a similar FeO spectral pattern as the one obtained after signal processing techniques over low resolution spectral signals. INTRODUCTION Visible-near infrared (VIS-NIR) spectroscopy is an optical contactless sensing technique commonly used to capture information about the emitted, absorbed, transmitted or scattered radiation in a physical or chemical process, with the presence or absence of an excitation light source such as a laser or a broad spectral band source. These techniques coupled with signal processing and machine learning algorithms, sometimes referred as chemometrics (Pisapia et al., 2018), can be found in processes such as: pharmaceutical (Kandpal et al., 2016); food (Coelho et al., 2016); combustion (Ballester & García-Armingol, 2010); siderurgy (Strakowski et al., 2014) industry, among others. In the extractive copper industry there are several technological developments using optical sensing techniques aimed to retrieve information about copper ore and concentrate mineralogical composition such as X-Ray Fluorescence, Qemscan® (Quantitative Evaluation of Minerals by Scanning Electron Microscopy) and X Ray Diffraction (XRD) analysis, however, because of the manual procedures to analyze the samples with these laboratory instrumentation, only discrete information during a daily based operation can be retrieved, making impossible for the operators to take decisions over the involved processes in real time. The aim of our research work presented here is to contribute with sensing and data analysis procedures based on VIS-NIR spectroscopy for the flash smelting process characterization, particularly in this paper, with the detection of FeO and CuxO molecular emissions in a laboratory scale setup.

Jan 1, 2019

By Akira Usui

Iron and manganese are very mobile metallic elements in the surface aqueous environment, particularly in the oceans. The elements are easily precipitated as oxides or dissolved back into water, controlled mainly by redox conditions, and the oxide precipitates often selectively accumulate other metallic elements. We have found clear evidence of fine-scale variations in chemistry, mineralogy, isotope composition and microstructures within various iron-manganese nodules and crusts, such as in the deep-sea basins and seamounts of the Pacific Ocean, and in shallow waters in the Baltic Sea. The patterns of variation with depth (that is time-lapse profiles of the deposits) are often correlated among samples and sometimes between remote localities. These fine-scale variations most probably reflect past depositional conditions and possibly image the environmental change, although they remain to be correlated to any physicochemical, geological, or oceanographic parameters. The hydrogenetic ferromanganese crusts have grown widely in the northwestern Pacific, accelerated by intensive circulation of oxygenated bottom waters during the last several millions of years, or earlier. The fine-scale (in millimeter) in-depth compositional and textural patterns with Be-10 growth-rate curves suggest significant changes in growth rate and also occasionally show a common microstratigraphic pattern among samples. Some of the samples indicate a correlation in growth pattern between remote locations, while others suggest short-range difference of oceanographic conditions with water depths.

Jan 1, 2004

By Edgar C. Bain

A NUMBER probably a sizable group of person with a dominant interest in metals maintain contact with the developments in ferrous metallurgy by reading week by week, as time permits, some four or five periodical devoted in considerable part to this field. It seems possible that some of these, like ourself, find it difficult to see the net results of the development day by day in clear perspective, The impression sometimes seems blurred by the uninterrupted succession of so many accounts, or out of focus from the very impact of so many reports of new things enthusiastic, well written, and understandable though they usually are. It is at times almost as though one were trying to observe, from a fastmoving vehicle, objects all too near at hand. Or perhaps this impression is merely a manifestation of our individual hyperopia ; in which case we should content ourself with an observation that it would be more satisfactory on the whole to discuss in 1941 the metallurgical advances of 1930-35 than those of

Jan 1, 1941

By Franklin H. Allison

The influence of cobalt and nickel on the properties of steel might be readily expected to be very similar. The two elements occupy close and somewhat unusual positions in the periodic table, their chemical behavior and compounds are so completely analogous and their various physical properties, including the ferro-magnetic characteristic, show such 3 remarkable correspondence, that there is no doubt of a strong resemblance existing between these two metals. However, the variety of properties that are obtained from steel is due largely to the fact that the element iron possesses allotropic forms. Alloying elements that affect these allot ropic forms, or alter the nature of the allotropic changes, exert a profound influence on the resulting steel. In the case of nickel and cobalt, although these elements are very similar chemically and physically, it is found that they differ distinctly in their individual effects on the critical points of iron. Both nickel and cobalt form a series of homogeneous solid solutions with iron at temperatures above 1500" F. The difference in their behavior does not occur until changes begin to take place in the solid state below this temperature. An inspection of the respective thermal equilibrium diagrams at the lower temperatures makes the opposite effects of nickel and cobalt clearly evident. Effect of Nickel and Cobalt in Binary Alloys with Iron The binary diagram of iron-nickel has been investigated by a number of workers. The lower temperature portion in Fig. 1 is reconstructed from the data of D. and H, Hanson.1 The diagram of iron-cobalt, shown in Fig. 2, is taken from the work of Ruer and Kaneko.2 Masumoto3 has recently discovered a lower critical point in cobalt and this has been added to the diagram. In both diagrams the space lattice structures as determined by Andrews4 have been included. It is interesting to note

Jan 1, 1927

Jan 1, 1928

By Edgar C. Bain, William E. Griffiths

The results of an inquiry into the structural nature of some 70 iron alloys containing both nickel and chromium over a considerable range of concentration are briefly described in this paper. This study is a part of a comprehensive program of investigation into alloys involving chromium in progress at the Union Carbide and Carbon Research 1aboratories. All the compositions studied contained carbon in amount comparable to commercial alloys. The B Constituent In addition to locating the limits of composition for the three principal types of structure (polyhedral ferrite, martensite and austenite) and their combinations, certain other features of the system were observed. A hitherto undescribed brittle constituent (designated here as the "B constituent") was discovered. It is very hard, non-magnetic and forms in two modes from chrome-ferrite by recrystallization. It is the stable low-temperature condition for the equal-proportion chromium-iron materials containing less than 10 per cent. nickel. Although it partakes of the nature of an inter-metallic compound, yet it may exist over a considerable range of composition. It is non-existent above a temperalure zone, varying with composition, from 800° C. to 950° C., and heating above this critical temperature develops chrome ferrite persistent after average cooling rate; a few hours just below this temperature will develop the complicated brittle crystalline type. The B constituent, when found in the grain boundaries of alloys of lower chromium content, contributes a serious brittleness removable, however, by heating and cooling rapid enough to prevent its re-format'ion. By suitable means of precipitution, the hard B constituent can be made to strengthen the already stiff alloy matrix in the manner of submicro-scopic particles, as exemplified in duralumin or the Sykes iron-tungsten and iron-molybdenum alloys. A possible explanation is offered for the familiar brittleness developed in chrome iron at temperatures above about 475" C. and removable by

Jan 1, 1927

By Francis F. Lucas

A microscope objective of given numerical aperture, when used with light of given wave length, has some fixed limit of resolution. This may be expressed as potential resolving ability—the ability to resolve is inherent in the lens but whether this limit is achieved in practice is quite another matter. Nearly 50 years ago Abbe evolved theoretical considerations which indicated that the ability of a lens to resolve detail is directly proportional to twice the numerical aperture of the objective and inversely proportional to the wave length of the light used. It is true, unquestionably, that as the numerical aperture of the objective is increased the potential resolving ability of the lens is increased and likewise when the wave length of the light used is decreased, the degree of resolution is increased. Whether Abbe's formula expresses the exact relationship is not a matter of great concern. It suffices to know that to improve resolution, other things being equal, two avenues of approach are available. Either the numerical aperture of the objective may be increased or the wave length of the light decreased. With the apochromatic system it is possible to employ successfully wave lengths from 400 to 500 uu and still secure reasonably short exposures. The present limit for numerical aperture is 1.40 N. A. although objectives of 1.60 N. A. are now an experimental possibility for metallurgical work. Thus certain well defined limits are set for those who work within the range of the visible spectrum. In order to take advantage of the increase in resolving power which accompanies a decrease in the wave length of light employed, Dr. A. Kohler and Dr. M. Von Rohr of the Zeiss Scientific Staff developed the "monochromats." These are quartz objectives corrected for the single wave length 275 uu which lies in the ultra-violet region of the spectrum. They also developed a series of quartz oculars and a complete photo-micrographic equipment with which to use the quartz optics. Quartz must be used for the optical parts because glass absorbs ultra-violet light almost completely. Thus there was made available about 20 years

Jan 1, 1926

By C. H. Herty

The results of a study of the open-hearth process from the physicochemical viewpoint are given. This study includes experimentation in small laboratory furnaces and in standard 100-ton furnaces. The behavior of manganese, carbon and phosphorus are quantitatively explained. The action of "residual" manganese is discussed with reference to its relation to iron oxide dissolved in the metal. The solubility of CO in steel and its relation to dissolved FeO and carbon is given. The equation for phosphorus elimination has been tested out on a 200-ton furnace and the results are given in the text. The effect of temperature and slag composition on the elimination of metalloids in the basic open-hearth process has been qualitatively understood since the early days of steel making. The quantitative effect has, however, only recently been brought to attention. The effect of slag composition has received more attention than that of temperature, primarily because the range of finishing temperatures in the basic open-hearth process is small compared to the large variations found in the composition of the slag at different periods during the process, and to the variations occurring with the use of raw materials of different degrees of impurity. The effect of slag composition on the elimination of metalloids has been studied by Styril from the thermochemical standpoint. This method is open to serious errors, in that thermochemical data at 2900' F. are very inaccurate and in many cases completely lacking. Feild2 has calculated equilibrium constants from the rate at which the metalloids are eliminated. The effect of slag viscosity on rate of elimination will affect the constants calculated by this method. Whitely,a Colcough4 and others have used slag compositions as the basis for calculation of constants by which the extent of elimination may be calculated.

Jan 1, 1926

By K. Huessener

In presenting the following data on combustion in the open hearth furnace and the advisability of automatic combusion control, the author finds himself much more severely handicapped by the lack of reliable test results than he had anticipated when he first undertook to write this paper. In order thoroughly to investigate how the results of an open-hearth furnace are influenced by combustion, one would have to draw up a large number of heat-balance sheets, as Kinney and McDermottl have given for one heat in their extremely able paper on "Open Hearth Efficiency,' presented before the American Iron and Steel Institute on October 27th,1 1922. Instead of covering only one heat, however, such heat-balance sheets would have to embrace a large number of heats, and not only for one kind of fuel, but for all the various fuels in customary use. Use of Radiation-protected Pyrometer Such tests necessitate extremely careful temperature readings, and here the first serious difficulty presents itself. Nearly all the temperature readings so far published have been taken with thermocouples for the lower ranges and with optical or radiation pyrometers for the higher ranges. This method of measuring reveals the temperature of the surrounding walls, or in the case of optical or radiation measurements, the temperature of that part of the opposing walls which has been focused by the instrument. The error in ascertaining the temperature of the gases entering or the waste gases leaving the checker chambers is probably not very large, as the flowing gases impart their temperature to the walls of the flues. On the other hand, the uptakes, where the preheat temperature of gas and air are usually measured, are under the influence of radiated heat from the port ends, and correct temperature readings can here be taken only by using a radiation-protected pyrometer of the aspirating type.

Jan 1, 1926

By J. M. Gaines, C. H. Herty

It is a matter of frequent record in the literature that manganese will desulfurize molten iron under proper conditions. Particularly has much been written with regard to this action in the mixer, and numerous reports have been published describing experiments in which advantage was taken of this phenomenon in order to obtain a purer iron for the open hearth. The question of sulfur elimination in the ladle has, however, received comparatively little attention. The reaction by which sulfur is removed is considered to be: FeS + Mn = MnS + Fe. The manganese sulfide, being but sparingly soluble in the iron, and of a lower density, will rise from the body of the metal and collect as a slag on the surface. It is therefore an action taking place solely in the metal, and independent of interaction between slag and metal. As will be shown later the presence of slag on the metal tends to offset the effect of manganese elimination. It is this fact which distinguishes desulfuriza-tion in the ladle from desulfurization in the mixer, for it has been shown1 that the amount of sulfur eliminated in the mixer is closely tied up with the composition of the slag. Experimental Procedure In order to ascertain the extent of and the factors controlling this elimination in the ladle, several casts were sampled carefully at the blast furnace and again when the ladles were being emptied, either at the mixer, open hearth, or foundry. If the sulfur content varied from ladle to ladle at the blast furnace the average sulfur content of each ladle was obtained by integrating the curve "sulfur vs. time " for the cast under

Jan 1, 1927

By L. S. Darken

It has long been recognized that the driving force in an isothermal diffusion process may be regarded as the negative gradient of the chemical potential (partial molal free energy) of the diffusing substance. This equivalence is exactly analogous to the fact that a mechanical force is the negative gradient of the potential energy. Nernstl in 1888 expressed these driving forces in terms of osmotic pressure, which is directly related to the chemical potential and free energy. The relationship between the diffusivity, mobility and activity coefficient of electrolytes in aqueous solution has been developed in great detail by Onsager and FuossZ with results which have recently been confirmed experimentally by Harned and Nuttall. This interpretation of the driving force in isothermal diffusion has been discussed earlier by the author,4,5 who pointed out4 that "for a system of more than two components it.is no longer necessarily true that a given element tends to diffuse toward a region of lower concentration even within a single phase region"; departure from the behavior of an ideal solution may be so great that the concentration gradient and the chemical potential gradient, or activity gradient, may be of different sign, thus giving rise to "up hill" diffusion. Since, in the discussion of that paper,4 some skepti- cism as to the validity of this conclusion was expressed, it seemed desirable to adduce experimental evidence to support it. Evidence of such diffusion in nonmetallic systems has already been reported. For example, it was observed by Hartley" in a series of experiments in which sodium chloride diffused from a saturated solution in about 5 pct acetone in water into a solution virtually free of salt but with essentially the same acetone concentration. Specifically, a wine glass containing crystalline salt and saturated solution was totally immersed in a large glass cylinder containing the acetone-water solution without salt; the difference in specific gravity was such as to prevent convection. Diffusion of salt was accompanied by a marked depletion of acetone in the wine glass; after 3 days the acetone concentration decreased from 5.37 pct at the top of the glass, where the salt concentration was low (0.93 pct), to 1.84 pct at the bottom where the salt concentration was high (21.64 pct). This "uphill" diffusion was found to be such that the partial pressure (activity) of acetone was essentially equalized throughout the system when a steady state gradient of sodium chloride was maintained. In order to demonstrate the existence of such diffusion in metals, a series of four weld-diffusion experiments was made. In these measurements pairs of steel of virtually the same carbon content, but differing markedly in alloy content, were welded at the end and held at 10500 C for about two weeks. Subsequent analysis showed that carbon had diffused so as to produce an inequality

Jan 1, 1949

By J. E. Crawshaw, Francis B. Foley

In the first report1 disks of steel of known composition and history were exposed, under carefully prescribed conditions, to impacts of explosion products resulting from the explosion of 50-gm. charges of explosives having well-determined rates of detonation, or to impacts of a weight of known mass, falling through measured distances. There were available at the Bureau of Mines Experiment Station five explosives, having rates of detonation of 5716, 4470, 3190, 2296, and 1523 meters per second. It being desired to continue this exposure downward, and no explosives with a lesser rate of detonation being at hand, resort was had to the impact of a falling weight, the differences in the velocity of impact being attained by varying the height from which the weight was allowed to fall. It was expected by this means to demonstrate experimentally that the development of Neumann bands was determined by the suddenness of the deformation of the metal in which they were produced. But while progressive deformations were obtained with the explosive charges, the falling-weight method failed because the tup was progressively deformed, also the disks were so flattened as to be unfit for metallographic examination. A return, therefore, has been made to the use of explosives as the source of energy, an air-gap being interposed between the charge of explosive and the disk, as the effect diminishes as the function of the distance between the charge and the object on which the products of its explosion, or the shock wave from its detonation, impinge. The details of the arrangement of the tests by the air-gap method were the same as those described by Foley and Howell,2 except that after the system had been set up and the desired apparent specific gravity for the explosive attained by tamping it, the small lead block, with the steel disk adhering

Jan 1, 1926