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By R. J. Sandrea, S. M. Farouq Ali

The results of an experimental and theoretical study of the effects of rectilinear impermeable barriers and highly permeable channels on the sweep efficiency and conductivity of a five-spot network are presented. The study was carried out using Hele-Shaw, and conductive sheet analogs for both. normal and inverted flood patterns. A functional relationship was developed which provides quantitative prediction of the above parameters; i.e., sweep efficiency and conductivity, for the nonhomogeneous system. To evaluate this, it is necessary only to measure the interference modulus of the obstacle using a simple expression. The results indicate that impermeable barriers, with an interference modulus greater than zero, always cause a decrease in the conductivity and the sweep efficiency of the pattern. On the other hand, permeability channels do not have a significant effect on these parameters, unless they are located along the streamlines. The study also discusses a method of formulating the difference equations pertaining to the two-dimensional Laplacian in a system containing rectilinear barriers. In addition, a technique is described for tracing the progress of a free surface, using marked particles, in a stream containing discontinuities SuCh as those occurring at the extremities of barriers. The above computational scheme was used in a digital computer program to simulate results of the Hele-Shaw analog. The computed values of sweep efficiency mere in good agreement with the experimental values. INTRODUCTION At the present time waterflooding remains the most widely used technique for the secondary recovery of oil. Among the numerous factors that affect the performance of a waterflood, the areal sweep efficiency constitutes one of the most critical parameters. It is a function only of the geometric distribution of the wells for a homogeneous medium and unit mobility ratio. Geological considerations, however, such as the presence of sealing faults or solution channels in the rock matrix, would generally exert an adverse effect on the areal sweep efficiency of a waterflood network. Surprisingly little information is presently available on the quantitative implications of such permeability interferences. It was the object of this investigation to consider the presence of rectilinear, impermeable and highly permeable interferences in an otherwise homogeneous five-spot pattern, and to analyze their effects on the resulting sweep efficiency and pattern conductivity. The experimental phase of the study was conducted using two different models: the Hele-Shaw flow cell and the field plotter. For experimental convenience, the geometric boundaries of the five-spot were assumed to constitute streamlines even in the case where the interference was asymmetrically placed with respect to a repeated five-spot pattern. A second object of the study was to develop a computational scheme for numerically calculating the pressure distribution in a five-spot flow pattern containing rectilinear, impermeable barriers, and to use this distribution to compute the sweep efficiency. EXPERIMENTAL PROCEDURE HELE-SHAW ANALOG The Hele-Shaw analog was used both as a visual model and for determining the sweep efficiency for systems involving impermeable barriers. The physical limitations of this model as a means of experimentally studying the motion of a fluid in porous medium have been adequately discussed elsewhere.2,7 Likewise, it can be easily verified that the analogy remains valid when a portion of the region between the plates contains an obstacle of the same thickness as the distance between the plates. The model used in this study was composed of

By S. Stutz

Coal, like most other minerals, only exceptionally occurs in a sufficiently pare state to he directly available for general manufacturing purposes. And even where this is the case, the small coal or slack is usually more impure than the lump coal, as the slate, clay, etc., from the roof and bottom of the vein become mixed with it in the handling it undergoes. These impurities often exceed ten or more per cent. in addition to the impurities of the coal itself. The most common impurities of the coal are slate, or shale, clay, and sulphur. The latter occurs in different forms, but moat frequently as bisulphide of iron, or iron pyrites, and as sulphate of lime, or gypum. In both cases the impnrities add greatly to the amount of ash, and where they are present in considerable quantities the raw coal, and still more the coke made from it, is unfit for the manufacture of iron. Coke will coutain on an average at least fifty per cent. more ash and sulphur than the ram coal from which it is made. To the manufacturer of iron every additional per cent. of ash which his coal or coke contains is a source of additional expense, seemingly small, and yet very important in the aggregate. In the blast-furnace, for instance, the ash must be heated up to the melting-point, and, since it is composed largely of refractory substances, the consumption of carbon in melting it will be equal to at least one-half of its weight; that is, a certain part of tile coke is consumed for the melting and fluxing of the ash and is lost. Besides this, it is well enough known to the iron-master that coke containing lees ash makes the &lag or cinder more liquid and less incliner1 to stick to the walls of the furnace. Fuel containing much sulphur produces generally a white iron, poor in carbon, while from the same ore arrd flux, with a pure fuel, a good foundry iron might be obtained. The work of separating slate, sulphur, etd, from the coal has as yet only been successfully accomplished by the washing process. This process depends for its success on the differences in the specific

Jan 1, 1881

By Roswell P. Angier, Herbert S. Kalish, Henry H. Hausner

POWDER metallurgical methods as applied to zirconium are of great interest because they permit not only the fabrication of parts directly to shape with a minimum loss of material but also the utilization of scrap, and the metal may be processed at temperatures well below the melting point. There are two difficulties involved in the melting of zirconium: 1—High vacuum is necessary for melting, and 2—zirconium reduces nearly all oxides so that it is difficult to find a suitable crucible material. The purest material, zirconium crystal bar, is expensive, and the methods of subsequent fabrication are limited. Cold rolling or extrusion of zirconium crystal bar is suitable for making certain shaped parts, but where melting is involved, the purity of the metal is invariably decreased, and a method of casting to a definite shape does not seem to be feasible. Where it is necessary to hot roll, zirconium must be covered with a steel or copper jacket to protect it from the air. This is necessarily a costly operation. Where annealing of zirconium is necessary it must be conducted in a high vacuum. In an investigation of powder metallurgical methods for zirconium, the zirconium powder used should be characterized by the following properties: 1— Highest degree of purity, 2—uniformity in particle shape and particle size distribution, 3—low compression ratio, and 4—satisfactory strength of the compacted powder (green strength). Zirconium powders have been made by two methods: By the reduction of zirconium tetrachloride (ZrC1,) with sodium,2' *•B "nd by the reduction of zirconium oxide with calcium and calcium chloride." The first method represents one of the earliest attempts to make pure zirconium metal, and the sintered product from this powder is extremely brittle. The second method of making zirconium powder is far more successful, but the powder made in this way has an extremely low apparent density and, therefore, a high compression ratio which makes it difficult to use it for powder metallurgical purposes. For these reasons the above-mentioned zirconium powders were not used in this investigation. To obtain sintered zirconium compacts of highest 'purity and good ductility, it was first necessary to produce a suitable powder. Pure zirconium has been made chiefly by two methods. The iodide method, from which the product is "crystal bar" zirconium, was developed first.'." By this purification process very soft, pure, and ductile zirconium metal can be produced. The second method, developed by the U. S. Bureau of Mines, is the reduction of zirconium chloride with magnesium." The sponge zirconium thus produced is also soft, pure, and ductile.

Jan 1, 1952

By J. H. Waxweiler, L. C. Ikenberry, R. J. Bendure

Carbon which is present as insoluble carbides in austenitic stainless steels can be measured quantitatively by dissolving the steel in iodine-methanol and analyzing the residue for carbon. Severe sen-sitization was observed in Type 302 due to precipitation of only 0.003 pet carbon. Both cold work and the presence of delta ferrite caused a marked acceleration in rate of carbide precipitation. Carbide precipitation rates in 17-7 PH were stzulied for the austenite conditioning and also the aging heat treatment. CARBON and its compounds exercise a major influence on the properties of stainless steels and their response to thermal treatment. Sensitization in 18-8 type stainless steels has been the subject of numerous investigations throughout the years. Bain, Aborn, and utherford," and Binder, Brown, Frankss all studied the effects of heating austenitic stainless steels in the temperature range of 1000° to 1500°F. The primary purpose of most of these studies was the investigation of susceptibility to in-tergranular attack in acids due to these sensitizing heat treatments. Intergranular precipitation of carbides was always associated with intergranular attack but it was recognized2 that severe attack could occur with but minute quantities of precipitated carbide. Mahla and ielsen utilized the electron microscope to make a significant contribution in illustrating the appearance and method of growth of chromium carbides during sensitizing heat treatments. However, as they stated, their studies of residues could not be used to obtain a quantitative measurement of the amount of carbon which was actually precipitated. The aim of the present investigation was to devise a relatively fast, simple method for the quantitative measurement of carbides in stainless steel. EXPERIMENTAL WORK The initial investigations were made to determine the best means of separating carbides from the matrix. A number of dissolving media were tried using both chemical and electrolytic attack. Qualitative examination of the extracted residues by X-ray diffraction indicated that solution in iodine-methanol would furnish a good means of separation. Consequently, further work was pursued along this line. The method is quite simple. The sample in the form of millings or nibblings is dissolved in iodine-methanol solution at room temperature (6-g iodine, 25-ml methanol per g of sample). The insoluble residue containing the carbides is separated by suction filtration through an ultra-fine glass filter disc. This is a very fine filter medium that will retain particles as small as 0.1 to 0.2 p in diameter. After washing with methanol and drying, the filter disc and residue are placed in a conventional combustion carbon-tube furnace and the carbon determined gravimetrically. Using this technique it was found that reproducible insoluble carbon values were obtained. However, since such small amounts of insoluble carbon were obtained on Type 302 after sensitizatipn at 1250°F and 1500°F, the values were confirmed by a second method. In the second method the sample was dissolved with copper potassium chloride and filtered through a millipore paper. This treatment dissolves the matrix but leaves undissolved practically all of the carbon irrespective of how it is present in the steel. The amount of insoluble carbon present as chromium carbide is determined by calculation from the analysis of the residue for chromium and iron. The derivation of the formula used for this calculation is discussed later. The values obtained by the indirect copper-potassium-chloride method were in agreement with those obtained by the iodine-methano1 method. See Table I. It should be pointed out that the sensitivity of the direct combustion method is not too high when the amount of carbide present is small. This is due primarily to inherent blanks and to analytical errors such as weighing. For this reason it cannot be stated with any degree of certainty that there is a significant difference between values of 0.002 and 0.005 pct. Having confirmed that the iodine-methanol extraction gave a quantitative measurement of the precipitated carbides in Type 302, exploratory tests were conducted on Armco 17-7 PH stainless steel. Samples from commercial Heat 54807 were solution annealed at 2000°F, water quenched and heated at 1250" and 1500°F, and water quenched. The analysis of Heat 54808 is as follows:

Jan 1, 1962

By C. D. Rugen

GROUND raw material as fed to the cement kiln generally is a mixture of two to four components, each of which may have widely varying physical and grindability characteristics. Chemically similar materials found in the same or different deposits may also differ appreciably in physical properties, depending on their crystalline structure. The calcareous or principal cement raw material may vary from a soft chalky limestone or friable cement rock at one plant to a hard limestone or oyster shell at another plant. Argillaceous materials include clays, shales and granulated slag. Siliceous and/or iron-bearing material, including sand, iron ore and cinders, may also be required in addition for certain types of mixes. Frequently differences in grindability characteristics are not given the attention they deserve in comparing grinding results at one plant with those at another or in selecting suitable circuits or equipment. Many types of crushing and grinding units are used, with numerous open and closed circuit arrangements. Both wet and dry processes are used successfully. When rebuilding or installing a new grinding department, the choice of process or circuit in some cases may be dictated by the nature of the materials being ground but in other cases it may be the result of good salesmanship or a compromise. An over-all evaluation of wet process vs. dry process grinding should not be made without considering the effects on all other producing departments in the plant. In general, the more recent grinding installations, both wet and dry, have employed closed circuits, but many older open circuits are still in successful operation. In our experience, closed-circuit raw grinding pays, because of lower power consumption and less operating labor per ton of product. However, some dry open-circuit mills with improved equipment and operating methods compare favorably in performance with dry closed-circuit units. CHARACTER OF GROUND RAW MIX (KILN FEED) Grinding in the cement plant in general requires a considerably finer product than in most ore-grinding operations. A distinction between fineness of kiln feed and of cement may be made in that kiln feed preferably should be ground to a limiting size, whereas finished cement should include a range of size fractions including sufficient fine flours to give a product with satisfactory physical qualities. Grinding raw mix for kiln feed therefore is more comparable to ore grinding, although the limiting size is smaller. Most kiln feeds are ground from 85 to 95 per cent passing 200-mesh, depending on mix composition. Some cement chemists believe that raw materials cannot be too fine, since finer particles theoretically combine more readily and intimately in the kiln. However, there are certain definite practical objections to extremely fine kiln feed, such as loss of kiln dust, unstable material flow through the kiln and greater difficulty in control of chemical composition due to dust loss, and the disproportion of fines from the more easily ground component. Our

Jan 1, 1945

By L. F. Porter, G. J. Dienes

The effect of netltron irracliation on mart ensite transformation in the iron-nickel system was studied by means of electrical resistance and magnetic induction measuremertts. Irradiation lowers the M8 temperature of the allay, causes changes in the electrical and magnetic properties of the high-temperature phase which indicate either an accelemtion of phase separation or a clustering of nickel, and enhances strain recovery on specimens partially transformed to martensite prior to irradiation. Possible mechanisms to account for the effects; are discussed. 1 HERE is a good deal of evidence to indicate that neutron irradiation is capable of affecting phase changes in metals and alloys. While the mechanism of the effect often is not well understood, such studies hold promise of improving our understanding not only of irradiation damage but also of the phase changes involved. To date systematic and detailed investigations have been made of the influence of nuclear radiation on order-disorder transformations in the copper-gold, nickel-manganese, and copper-zinc system, and on precipitation reactions in the copper-iron, nickel-beryllium, and copper-beryllium system.' These solid-state reactions are diffusion controlled and the results can be explained largely on the basis of enhanced diffusion due to the presence of irradiation produced vacancies. Reversion of low-temperature eutectoid phases to the high-temperature phase has been observed in the fissionable uranium-molybdenum and uranium-niobium systems.2 Here it is necessary and logical to postulate a displacement spike mechanism to account for the effect. The only case of irradiation induced diffusionless transformation in metals is the allo-tropic transformation of p to a tin reported by Flee-man and Dienes. 3 They found that neutron irradiation markedly decreases the incubation time for transformation, but the mechanisnl is not well understood. Another diffusionless transformation which one might expect to be influenced by neutron irradiation is the martensite transformation. This transformation is known to be sensitive to strain, structural hardening, and the presence of imperfections.6,7 Since the transformation is diffusionless, one also

Jan 1, 1960

By R. E. Allen, A. C. Jephson

ELECTROLYTIC zinc plants of the American Smelting and Refining Co. are located adjacent to the present city limits of Corpus Christi, Texas. The original plant commenced operations during 1942, and is designed for the production of special high grade zinc from zinc sulfide concentrates.' Subsequent changes include the erection of an additional acid plant during 1950, and additions for increased generating and production capacity during 1951. New Electrolytic Plant—The new electrolytic plant is a separate unit erected for the treatment of densified fume produced at Asarco plants located in El Paso, Texas and Chihuahua, Mexico. Construction was completed and operation commenced during June, 1953. Decision for the erection of a separate plant for the treatment of densified fume is based on several factors. One of the principal reasons is the assurance of continued production rate of the original plant, which might have been jeopardized by combined treatment of calcine and fume. Of equal importance is the advantage of locating a plant on a site with adequate space for eventual expansion. General Description—The new plant for the treatment of densified fume consists of four main buildings for the following operations: storage and grinding of fume, leaching and purification, electrolyzing and casting, and rectifier units. Auxiliary buildings include a baghouse, reagent storage, and a lunch room. Leaching of ground fume with electrolyte from the cells is a batch type operation in tanks equipped with mechanical agitators and weightometers. Completed leaches are pressure filtered, the resultant residue being recovered for shipment to El Paso by conventional use of thickeners, drum type vacuum filters, and a direct-fired dryer. Filtrates from the filter section are purified in mechanically agitated tanks, filtered after completion through plate and frame presses, and then pumped to an evaporative type cooling tower. Solution discharged from the basin of the cooling tower is collected in storage tanks for use in the cells. The cool purified solutions are pumped as required from storage to the solution circuit for circulation of electrolyte through the cells. Except for the addition of purified feed solution and withdrawal of electrolyte for leaching, the circulating system for the cells is essentially a closed continuous circuit that includes the use of evaporative cooling towers for control of solution temperatures. Aluminum cathodes and Ag-Pb anodes are used for electrolysis, which is maintained at a current density of about 82 amp per sq ft. Cathode zinc produced is melted in a gas-fired reverberatory furnace and then cast into slabs on a straight line casting machine. Unloading and Storage—Fume produced by the Chihuahua plant is shipped in box cars, and fume by the El Paso plant in hopper bottom dump cars. Shipments as received are weighed on a 7 5-ton capacity railroad scale, sampled, and then moved over one of the two unloading hoppers with a car puller. The cars are then unloaded with mechanized equipment, a car scoop being used for unloading of box cars and a car shaker for the hopper bottom cars

Jan 1, 1958

By David W. Wisecarver, James F. Reynolds

INTRODUCTION The Department of Energy is cooperating with Snowmass Coal Company near Carbondale, Colorado to introduce the longwall mining method in moderate to steeply pitching coal seams in the United States. This venture is part of a coal mining research program directed toward development, trial, and analysis of mining technique8 to improve production and recovery in the more difficult mining conditions such as thick, multiple, and steeply pitchly seams found in the Western U.S. The project at Snowmass is the first attempt in the United States to operate a longwall in a steep coal seam. Plans are to mine three adjacent, successively downslope panels in the eight foot thick seam which varies in pitch from 27 to 33 degrees. During this work, researchers and mine engineers are expected to obtain answers to many engineering questions relative to panel design and development, selection of face equipment and beet operating techniques and procedures. They are also committed to obtaining hard data on costs, recovery, production, safety, and behavior of underground mine structure as the three panels are mined. This information is essential to future mine engineering and profitable mining of pitching Western coal reserves. Development of the first trial panel was begun in 1979 and completed in June 1981. The longwall mining equipment was then installed in the starting room and retreat mining begun on August 11, 1981. Project duration is expected to be about five years during which over tm million tons of coal will be produced. TRAINING The longwall mining method is new to Snowmass. For years the mine produced coal by room and pillar methods using conventional techniques to mine upslope rooms and Alpine F6A miners to cut entries and rooms on strike. Miners were experienced in room and - pillar mining from other mines. News of the longwall demonstration was received enthusiastically by Snowmass miners. Employee interest in the project was 100%. However, there was minimal longwall experience on site. In fact, most of the work force had not even seen a longwall. Mine and company management were well aware of the immediate need to develop trained longwall face mining crews and maintenance people qualified to work on longwall equipment and also expertise in longwall planning, equipment selection, power distribution design, ventilation requirements and panel development. The first approach to answer this huge deficiency in longwall mining experience was obviously training. Hence a training program directed toward those mining specifics most urgent to the beginning mining phases was initiated in mid-1980. Classroom lectures and hands on training, using instructors from equipment suppliers and available company longwall expertise, was conducted in longwall subjects to include face mining procedures, panel development, operation of equipment, equipment assembly and maintenance, electrical circuitry and controls, ventilation, move of longwall equipment, and safety procedures. At the same time, responsible engineers and foremen were sent on a tour of European pitching longwalls to see first hand how other mines working under similar seam conditions conducted their operations. Development techniques, types of equipment, methods for transport of men and materials, and ground control techniques were discussed with engineers, foremen and officials at each mine. This look at European longwall mining operations gave Snowmass good insight into the unique problems associated with longwall mining on 30' pitch. Mining considerations such as face conveyor/ support system slippage downslope, panel development, maintenance, safety considerations, manpower requirements, and haulage methods were covered with European experts

Jan 1, 1982

By AIME AIME

THE Wednesday morning session was devoted entirely to the consideration of the tentative code for coal mine ventilation. A. W. Hesse is chairman of this subcommittee. E. A. Holbrook presided at the session and assisted by A. W. Hesse and George S. Rice, gave the historical background of the movement for a ventilation code. They stressed the point that this was to be an engineer's code, and that it was hoped that it might serve as a valuable guide to operating companies in securing greater efficiency as well as safety in ventilation. The discussion was continued into the afternoon session, and by adjournment the entire' code had been covered.' Many sections were referred back to the Committee for further study and several new sections were suggested. The various opinions and new ideas brought out during the discussion proved very valuable and. contributed much to the progress being made in the preparation of this code.

Jan 1, 1929

By J. J. Stokes

Literature on the electrolysis of aluminum from cryolite melts and on the structure of these melts is surveyed critically. Data on density, freezing point, and other properties are reviewed. Theories of the electrolysis are examined in the light of these data. Two theories are presented which account equally well for the observations. ALTHOUGH the production of aluminum is a large-scale industrial process, consuming approximately 3 pet of all of the electric current generated in this country, the mechanism of the Hall Process remains a 70-year-old mystery. It is a remarkable fact that the aluminum industry, which was established largely through research and owes much of its growth to research, still employs as its basic process the one developed by Charles Martin Hall while he was still a young man working in a woodshed. There are, of course, modifications in detail and a tremendous expansion of the size of the units used, but basically the process employs carbon anodes and a carbon-lined iron vessel as a cathode for the electrolysis of alumina dissolved in molten salt. Of the almost infinite variety of salts available, the relatively minor Greenland mineral, cryolite, 3NaF.A1F3, is still the only one which gives good performance in the electrolysis. In the early days, the process was thought of as a simple one. The dissolved alumina dissociated and, during the electrolysis, the aluminum was carried to the cathode where it was discharged and collected in a pool of metal. The oxygen was carried to the carbon anode where it reacted to form primarily carbon dioxide together with some carbon monoxide. About the only virtue that can be claimed for this hypothesis is that of simplicity. The actual mechanisms must be tremendously more complex. This paper is devoted to a rather narrow part of the whole subject, namely, what ions are present in the bath, and by what mechanism the current is carried. The complexity of the literature on this system is demonstrated in Table I, which shows the ions postulated as being present during the process. This system is not easy to investigate. Cryolite melts at about 1000°C, so that all the investigations are at relatively high temperatures. Molten cryolite fumes in air, particularly if excess aluminum fluoride is present. The cryolite changes composition on heating at 1000°C, principally by reaction with moisture in the air, but apparently also by reaction with oxygen. Cryolite reacts with most of the customary materials of construction, and those that are not attacked by cryolite seem inevitably to react with molten aluminum. Graphite is the only common material that is inert to the electrolytic bath. Pure cryolite can be held in platinum. There is hope that some of the newer refractories will stand up in bath, and their development for this purpose would be a major advance in the field. The techniques to be discussed, then, are not the most advanced ones. Rather, they are examples of old standardized methods applied under difficult conditions. The principal methods that shed real light on the mechanism are density, electrical conductivity, freezing-point lowering, transport number, viscosity measurements, and reactivity of bath with carbon dioxide. The first measurement to be discussed is density. This procedure is relatively straightforward. A hollow platinum bob is suspended by fine platinum wire from an analytical balance into the melt being investigated. Density1-4 of the system sodium fluoride-aluminum fluoride is shown in Fig. 1. There is a maximum in the density near the cryolite composition, but actually the maximum is on the NaF-rich side of cryolite, close to the composition NaF - Na3AlF8. Density measurements are also useful in giving a clue to the nature of cryolite-alumina melts.1, 4 On the first addition of alumina, density decreases, Fig. 2, although the density of alumina, either solid or liquid, is higher than that of cryolite. These density results indicate that the systems are not simple. A great deal of effort has been spent in measuring the electrical conductivity of molten cryolite and of cryolite with various additives. Conductivity measurements are quite easy for fused salts that can be measured in a dip cell, but no successful dip cell has been made available yet for cryolite. Recourse is had

Jan 1, 1959

By Arthur Notman

(San Francisco Meeting, September, 1915) SACRAMENTO HILL is a mass of granite porphyry intruded along a fault between Paleozoic sediments and pre-Cambrian schists in the Bisbee district, Cochise County, Arizona. The intrusion invaded both walls of the fault to a large extent, and the accompanying extensive mineralization of the Paleozoic limestones is the locus of the great high-grade copper orebodies of the Bisbee mines. Prior to 1909, although the presence of ore in the mass of the hill itself had long been suspected, systematic exploration had not been attempted. A few shallow pits on the surface here and there had disclosed some chalcocite with associated carbonates as stringers in a mass of strongly brecciated, silicified, and iron-stained porphyry. The workings in the surrounding limestones had penetrated the porphyry in a dozen or so places for some distance from the contact but had disclosed no ore. However, the rock had been largely altered to quartz and sericite and very thoroughly impregnated with pyrite and traces of the copper sulphides. A close geological study of the conditions, both surface and underground, strengthened these suspicions, and plans for prospecting the hill were made in 1909. Reference to the accompanying illustrations, Figs. 1 and 2, will give an idea of the general appearance of the surface. The mineralization is more intense in two main zones, one at the west end and the other at the east end of the hill. The outcrop of the hill is elliptical and approximately 3,000 ft. long by 1,400 ft. wide. The Sacramento shaft, which is the main hoisting shaft of the mine and situated at the east end of the hill, as shown by the accompanying map (Fig. 3), offered a convenient base for prospecting that end of the hill, while the workings from the Holbrook shaft offered a similar opportunity at the west end. The choice of level for the first work was determined by analogy with the most favorable depth for enrichment below surface observed in the other disseminated deposits of the Southwest.

Jan 8, 1915

By Howard Scott

INVAR is the preeminent low-expansion metal by virtue of the fact that it can be prepared with a zero coefficient of expansion at atmospheric temperature. This fact suggests that there is little room for improvement in the expansion properties of the low-expansion nickel steels. The inference is true, however, only so far as the expansion at and near atmospheric temperature is concerned, because the expansivity of invar starts to increase rapidly on heating above 100° C. and soon reaches the value of copper. Guillaume1 met this situation by increasing the nickel content above that of invar. By that expedient, alloys having low expansivity under higher temperatures were obtained, but not without a large increase in minimum expansivity. The increase in minimum expansivity with increasing nickel content severely limits the technical applications of these alloys at high temperatures. Prospects of improving the expansion characteristics of the nickel steels is offered by alloying. Search for an advantageous alloying addition by analogy with other alloy systems, however, is not productive because the low-expansion characteristic is unique with that system. The rule of mixtures usually gives a fair value of the expansivity of other solid-solution alloys, but in the iron-nickel systems gives a value of 18 X 10-6 per deg. C. whereas the actual value is 1 X 10-6 per deg. C. Apparently suitable additions are not to be deduced from such ingenuous considerations. Recognition of the fact that the temperature range of low expansivity in nickel steels is terminated with loss of magnetism affords a more promising basis for the selection of an advantageous element. One may expect from that fact that additions of nonmagnetic elements to the iron-nickel alloys are detrimental to the low-expansion characteristic. Indeed, carbon, manganese, silicon, copper and chromium are detri-mental to the expansion properties and no nonmagnetic element is reported to be beneficial. From the same viewpoint, the addition of a magnetic metal offers prospects of improvement. As two of the three ferromagnetic elements are already present in the

Jan 1, 1930

By J. Blodget Britton

IN the Journal of the Franklin Institute for May, 1870, there is published a description of a Colorimeter, together with a modification of the method proposed by Professor Eggertz, for determining combined carbon in iron and steel. An instrument of the kind there described, but of a little higher range, though in other respects not differing materially from the one originally made and used in the Iron-Masters' Laboratory, I now submit to your inspection ; and I propose, also, to make some determinations with it for the purpose of showing how quickly they may be made, and enabling you to form some judgment of what reliance can be placed in the results. Professor Eggertz proposed only a single standard, and the solution to be tested should be diluted to exactly correspond in color with that of the standard, and the per cent. of carbon calculated after carefully noting and making allowance for the measures of water used in diluting. In practice, difficulty was found in bringing the color of the normal solution down to the exact shade of the standard ; also other difficulties were met with in conducting the process, causing delay and interfering with the accuracy of the results. To materially overcome these, and after numerous attempts, an instrument such as is now before you suggested itself to me; and also I concluded to use a larger quantity of metal than directed by Eggertz, and, in addition, to filter the solution from its insoluble matter before making the comparison ; and, more recently, to use an acid of just such strength as would completely dissolve the metal without the application of heat. Experimenting with these changes from the original method I obtained reasonably good results. The instrument, you will observe, consists of a series of tubes, sixteen in number, two and a half inches long, and about half an inch in diameter, standing upright, and securely fastened in a light, portable, walnut-wood frame, but separated one from the other so as to allow just sufficient space between to place for comparison the tube containing the solution to be tested. The tubes are filled with

Jan 1, 1873

By H. l. Burghoff, J. S. Porter

THIS paper presents the results of an investigation of the effect of cold-working and annealing treatments upon the occurrence of preferred orientation in annealed brass wire. The subject has received less consideration than has the same phenomenon in annealed brass sheet or strip, and perhaps very properly so in view of the obvious and undesired results obtained in the forming or drawing of strip having preferred orientation, which results are in contrast with the lack of any spectacular visual evidence in wire. The factors of cold-working and annealing that control preferredness in strip are naturally expected to function similarly in wire. Indeed, one might expect the condition to be commoner in annealed wire, because the severity of the cold-working between anneals in commercial practice is usually much greater for wire than for strip. For example, a wire that is to be finished in the annealed condition on a diameter of 0.040 in. is commonly subjected to a final reduction of 96 per cent between the last two anneals, the large reduction being accomplished in the successive drafts of a multiple-die machine. Wire for rivets, for instance, on 0.125-in. diameter, although given a slight reduction of about 10 per cent after the final anneal, may have been given a prior reduction of 75 to 80 per cent. Barrett1 states the fiber axis of annealed 70-30 brass wire to be [111] with some indication of [100] as a secondary fiber axis. Croft and Sachs2 have reported briefly on some differences in brass wire with random and with preferred orientations. They showed statistical plots of the twin-band angles with respect to the wire axis or direction of drawing as observed on an axial plane. They also pointed out that the resistance of the wire to corrosion-cracking when externally stressed and exposed to a mercurous nitrate solution decreased as the degree of the preferred orientation increased. MATERIAL AND PROCEDURE All the wire for the investigation was processed from one. portion as cut for extrusion from a cast billet of the following analysis: 70.13 per cent copper; 0.01 lead; 0.01 iron; 0.02 nickel; 29.83 zinc (by difference). The billet section, 8 in. in diameter, was extruded hot to 3/4 -in. diameter, after which it was processed by alternate cold-drawing and annealing treatments as indicated in Fig. I. The earliest anneals in process were at about 1100°F. and the next to the last reductions by drawing were 58 per cent. The diameter of the finally annealed wire was 0.132 in. Semifinal anneals were at 800°F., 950°F. and 1100°F. and reductions of 47.5, 74, 83.5 and 89.5 per cent were employed in drawing to 0.132 in. The final anneals were at 875°F., 1050°F. and 1250°F. and were

Jan 1, 1944

By N. P. Goss

Asterism appearing in X-ray Laue diagrams is an extremely sensitive index of changes in the internal structures of individual grains of polycrystalline metals. It indicates the existence of various forms of subboundary structure or subdivision within the grain. The present viewpoint is that the grain is made up of lattice blocks having substantially the same size and shape.l-4 When these blocks all assume exactly the same orientation, the crystal is perfect and asterism is absent. Cleaves and Thompson5 observed that the hardness of iron is virtually constant over a range of grain sizes. It is quite possible that the subboundary structure caused this, and that the latter is just as important as grain size itself. While the experiments reported here are not conclusive, they do support this viewpoint. Metals can, under certain conditions, be prepared entirely free from asterism, but this preparation does not necessarily require long heating or slow cooling, as will be shown here. In this paper a distinction is made between mosaic and distorted grain structures but the difference is only a matter of degree. In a previous paper9 it was shown that the grains can become distorted even during heat-treatment. The block structure exists inherently, even in a perfect crystal; the size and shape of these crystallites, or lattice blocks, varies, depending upon a number of factors. Goetz, for example: has shown that a metal before crystallizing from the molten state must go through a paracrystalline phase with oriented groups of atoms about 10-l4 to 10-l5 c.c., or 10-15 cm. in size. These crystallites, or blocks, appear to survive the most drastic cold-working, for it has been shown, and more elaborately by Wood's recent work," that cold-working cannot reduce the size of these crystallites smaller than of the order 10-5 cm. The interesting correlation brought out by the experiments of Goetz and Wood is that the block size after severe cold-working is of the same order of magnitude as the groups that formed in the metal just before crystallizing from the molten state. The work of Ewald and Rennenger17 and the now classical experiments of Darwin and James12,13 all strongly suggest the existence of a periodic structure of crystal. lites smaller than the grain itself. Related to this effect is the appearance of veinlike markings in the microstructures. Ammer-man and Kornfeld,16 in their experiments, did not observe any evidence of veining in specimens of alpha iron annealed below A3 and believed that veining was not due to impurities in the iron, as Northcott16 suggested; veining was observed by them only in specimens annealed above A3. Hanemann,16 Schrader and Tangerding found that annealing in hydrogen did not diminish veining and so it could not be caused by oxides. They concluded that veining was due to a slight difference in the orientation of ferrite lattice blocks. This viewpoint is well supported by the evidence presented here.

Jan 1, 1941

By N. P. Goss

Asterism appearing in X-ray Laue diagrams is an extremely sensitive index of changes in the internal structures of individual grains of polycrystalline metals. It indicates the existence of various forms of subboundary structure or subdivision within the grain. The present viewpoint is that the grain is made up of lattice blocks having substantially the same size and shape.l-4 When these blocks all assume exactly the same orientation, the crystal is perfect and asterism is absent. Cleaves and Thompson5 observed that the hardness of iron is virtually constant over a range of grain sizes. It is quite possible that the subboundary structure caused this, and that the latter is just as important as grain size itself. While the experiments reported here are not conclusive, they do support this viewpoint. Metals can, under certain conditions, be prepared entirely free from asterism, but this preparation does not necessarily require long heating or slow cooling, as will be shown here. In this paper a distinction is made between mosaic and distorted grain structures but the difference is only a matter of degree. In a previous paper9 it was shown that the grains can become distorted even during heat-treatment. The block structure exists inherently, even in a perfect crystal; the size and shape of these crystallites, or lattice blocks, varies, depending upon a number of factors. Goetz, for example: has shown that a metal before crystallizing from the molten state must go through a paracrystalline phase with oriented groups of atoms about 10-l4 to 10-l5 c.c., or 10-15 cm. in size. These crystallites, or blocks, appear to survive the most drastic cold-working, for it has been shown, and more elaborately by Wood's recent work," that cold-working cannot reduce the size of these crystallites smaller than of the order 10-5 cm. The interesting correlation brought out by the experiments of Goetz and Wood is that the block size after severe cold-working is of the same order of magnitude as the groups that formed in the metal just before crystallizing from the molten state. The work of Ewald and Rennenger17 and the now classical experiments of Darwin and James12,13 all strongly suggest the existence of a periodic structure of crystal. lites smaller than the grain itself. Related to this effect is the appearance of veinlike markings in the microstructures. Ammer-man and Kornfeld,16 in their experiments, did not observe any evidence of veining in specimens of alpha iron annealed below A3 and believed that veining was not due to impurities in the iron, as Northcott16 suggested; veining was observed by them only in specimens annealed above A3. Hanemann,16 Schrader and Tangerding found that annealing in hydrogen did not diminish veining and so it could not be caused by oxides. They concluded that veining was due to a slight difference in the orientation of ferrite lattice blocks. This viewpoint is well supported by the evidence presented here.

Jan 1, 1941

By N. J. Grant, D. Carne, J. B. Seabrook

IT is unnecessary to review much of the literature on hydrogen embrittlement of steel since several excellent reviews and bibliographies exist.1-3 Hot acid pickling and cathodic charging have been known to cause hydrogen embrittlement of steel and have been used as laboratory methods to charge steels with hydrogen.4-8 Experimental Procedure The problem of prime concern in all instances, except in the work of Sims and coworkers,10 is that at no time was there a definite known hydrogen value reported which could be related to a particular value of the degree of embrittlement. It was the purpose of this research to determine the relationship between hydrogen content and degree of em-brittlement quantitatively. The 1020 stock used for the specimens was hot-rolled 7/16 in. diam rod of the following analysis: 0.19 pct C, 0.40 pct Mn, 0.012 pct P, 0.036 pct S' Vacuum-fusion analyses for nitrogen and oxygen gave 0.014 pct O2 and 0.0011 pct N2. Cathodic charging was used to cause embrittle-ment. The advantages of this method were that no quenching was necessary, the impregnation was reasonably controllable, and representative samples for analysis could be prepared simultaneously with the charging of the tensile bars. Analyses for hydrogen were made in a vacuum-fusion type of apparatus which extracted gas from the samples by fusion in a molten tin-iron bath' This apparatus, which has recently been described in detail elsewhere, will not be discussed here.". " Consecutive samples can be analyzed every 15 min with an accuracy of 0'03 ppm. A A from an electrolytic or pickling bath can be charged for analysis in about 3 min, and analysis completed in 15 min. Samples of as-received 1020 stock were analyzed and found to contain a negligible amount of hydrogen (0.06 ppm). Preliminary pickling and electrolytic charging gave highly variable results. Cold-worked samples showed higher values but ranged from 0.6 to 6.0 ppm of hydrogen. Charging at 90°C gave higher values of charged hydrogen, but troublesome films on many of the specimens resulted. It was not until a few drops of a catalytic poison, prepared from 2 g of yellow phosphorus dissolved in 40 ml of carbon disulphide,8 was added to the electrolytic cell that fairly consistent high values of hydrogen could be charged into the as-received 1020 steel at room temperature. The cell used is sketched in fig. 1. The anode and fixture for the tensile specimens were fastened to the cell cover as shown, and the specimen was screwed in place, centrally located with respect to the anode. At first, anodes of lead and graphite were tried, but they contaminated the electrolyte and gave a slight deposit on the specimen. Later, a platinum wire was used in the form of a uniform helix. A current of 2 amp, corresponding to about 0.5 amp per sq in. of cathode, was used for most specimens. The electrolyte was 4 pct H2SO4 solution. Fig. 1 shows the form of the special tensile bar, the main portion of which was an ordinary 1/4 in. diam, 1 in. gauge length test bar, except that two to four small cylinders of stock were left attached by small links to the bottom end of the tensile bar for the purpose of providing samples for hydrogen analysis. Thus the bars and samples were charged with hydrogen simultaneously and an analysis could be made while the bar was being tested mechanically. Experiments were performed to determine how representative the test cylinders were of the middle of the test bar proper. While the bar center was being analyzed, the small cylinder was stored in dry ice, since it had been shown that such storage prevents loss of hydrogen for many hours.12 The results of these checks are shown in table 1. The checks are very good (0.3 ppm) and indicate that it is permissible to use the small end cylinders to establish the hydrogen content of the tensile test bar proper-

Jan 1, 1951

By L. D. Fetterolf, G. T. Mahler, W. M. Peirce, R. K. Waring

Until recently, the only commercial method of producing magnesium has been fused salt electrolysis, despite a considerable amount of experimental work on the direct reduction of magnesium oxide. In this early work, a number of investigators demonstrated that magnesium oxide would react with any one of several reducing agents to produce magnesium vapor, but that the mixture of magnesium oxide and reducing agent must be heated to a high temperature even in a vacuum. In particular, it was demonstrated that silicon and aluminum are effective reducing agents and that when either of these is used the magnesium vapor can be condensed to massive metal. In spite of this knowledge, no successful commercial reduction process was developed, at least in this country, because of the operational difficulties imposed by the requirement of high temperature and vacuum and because of the high cost of the reducing agent. The outstanding experimental work done by Pidgeon, who carefully reviewed all of the known methods of making magnesium and then selected ferrosilicon reduction, overcame some of the operational difficulties. The process developed by Pidgeon comprises briquetting a mixture of calcined dolomite and reducing agent, preheating the briquets to about 600°C. in an externally heated alloy retort, reducing the MgO with silicon in an evacuated horizontal alloy retort heated externally to about II50 C., and condensing the magnesium vapor to a solid in a cold extension of the retort projecting beyond the front of the furnace. A major advantage of Pidgeon's process is that the retort is not cooled down between charges. Earlier investigators had used apparatus that necessitated cooling and reheating of the retort between charges. Early in January 1942, when the War Production Board was considering the Pidgeon process for quickly increasing the production of magnesium, The New Jersey Zinc Co. offered to have a research investigation of the process carried on, with the hope of assisting in its further development. This offer was accepted, and a two-retort pilot plant was built at Palmerton and put in operation on Jan. 29,1942. An intensive investigation of certain phases of the process was carried out in the ensuing four months. This investigation was completed in the last part of May 1942) and the pilot plant was then shut down. Subsequently, The New Jersey Zinc Co. was requested to have further development work done on the process, and a more extensive investigation was undertaken in August 1942 under contract with the War Production Board and under the supervision of the War Metallurgy Committee. This paper describes the ,phases of the investigation that are thought to be of sufficient general interest to merit publication.

Jan 1, 1944

By Michael J. Messel

OF the various minerals that occur in fibrous form known as asbestos, chryso-tile is the variety most in demand for commercial uses, and, last year, over 683,000 tons of the various grades were produced in Canada and United States, exclusive of African and Russian production, which figures are uncertain. Production has not been able to keep up with the increased demand, and an acute shortage exists. Canada, Russia, and Africa are still the most important producers. However, Russia consumes most of its production at home and exports very little. The United States consumes over 60 pct of the total production and produces only about 4 pct of the total from deposits in Vermont and small quantities from Arizona. This paper will review mainly, some of the more recent developments concerned with the extraction and processing of this fibrous mineral for various industrial uses, such as textiles, insulation, building materials and brake linings. Four of the more important factors that have influenced recent developments are: 1. The lack of discovering and developing new deposits of any important size to supply the increased demand. 2. Rapid postwar expansion of industrial uses, especially in asbestos cement products, together with in-rreased manufacturing facilities. Euro-peal) countries are again back on the market with their demand. 3. The ability of manufacturers to develop their technique of blending fibers and obtaining more utility value out of each ton of fiber, together with the utilization of shorter grades of fiber to obtain equally as good products. In the past, many manufacturers were wasteful in their use of fibers. 4. The struggle for reduced operating costs, in face of increased wages and prices of supplies, together with the necessity, at some mines, to change the method of mining from open quarry to underground. Most of the recent capital invested in the asbestos mining industry has gone into more efficient extraction of the fibers from the existing ore, especially in the recovery of the shorter grades. There has been very little new plant expansion. Progress in the utilization of shorter fibers has been so far reaching that some of the mining companies are retreating present tailings as they leave the mill, and others are considering retreating of the old tailing dumps for recovery of fibers that, until recently, were not saleable and were discarded as part of the tailing. Many of these dumps contain much valuable fiber from days when milling was very inefficient. It might be appropriate to mention here that the present known asbestos reserves of proved commercial value (excluding Russia) are being depleted at an alarmingly rapid rate, about 10,000,000 tons of ore is being mined annually. No new deposits have come into production during the last 15 years, with the exception of certain deposits in Africa, which are the most promising, and minor developments in Canada, Venezuela, Cyprus, Australia, and Brazil. The African deposits are the only ones that hold promise of developing large reserves. Unless new deposits are developed, in twenty years or maybe sooner, the supply picture will not be a very bright one. Stimulated by the acute shortage, increasing fiber prices and technical developments, many new areas are being prospected in Canada, United States, New Zealand, Newfoundland, South America, Europe, Africa, and China. From information now available, it appears that no real progress has been made in duplicating this rare development of nature by producing synthetic asbestos. The most promising experiments were carried out at the University of Leipzig, but they seem far from practical. There has been marked progress in fiber glass manufacture, but so far, it has replaced asbestos only in very few instances for minor uses. Asbestos ore and the fiber it yields are different in some respect at each mine and vary usually in the following: 1. Percentage of fiber content by weight to the gangue. 2. Variations in proportions of long and short fibers, some deposits being predominantly long fiber and others short fiber. 3. The hardness of the rock in which the fiber occurs. 4. The nature of the fiber, as to

Jan 1, 1950

By C. E. Schwab

A lead-zinc orebody, in fairly strong quartzite and with a dip of 35" to 60°, is block-caved by use of scrams in a stair-step pattern up the ore footwall. Scram linings to handle coarse muck and permit the use of folding scrapers are developed by the use of end-grain wooden blocks to reduce maintenance and keep operating cost to a minimum. THE Bunker Hill mine, since its discovery in 1885, has steadily produced a high grade of lead-silver-zinc ore. By the end of 1952 over 21,000,000 tons of this high-grade ore had been produced by square-set mining, and reserves in the mine continue to be very satisfactory both as to quantity and grade. For many years prior to 1941, mine production and mill capacity had been 1200 tons of feed per day. Closely adjacent to the mill, and stored behind dikes, coarse jig tailings had been impounded during the time preceding the advent of fine grinding and selective flotation. When manpower became short in 1941 and sink-and-float preconcentration was proved successful, mill capacity was increased to 1800 tons per day to treat these jig tailings economically. By 1946, because the supply of jig tailings was limited, underground exploration was started to discover and prove ore reserves of low-grade material which could be mined by an appropriate bulk mining method. During the years of square-set mining many possible areas of low-grade mineralization had been observed. One chosen for the first exploration work was sufficiently remote from active mining areas so that subsidence, if an ore-body were proved, would cause no problem. Also, old adits and workings were still open and in good enough condition so that exploration in the mineralized zone could be started with a minimum of preparatory work. In 1948 an orebody was proved of sufficient tonnage, of a grade about 2 pct Zn, 0.5 oz Ag, and 1.0 pct Pb. It was decided to use block-caving, the only appropriate mining method by which this grade of ore could be economically recovered. Exploration for additional reserves in other areas of the mine is continuing, but ultimate results are not known at this time. With more sink-and-float capacity, larger ball mills, and more flotation machines, mill capacity was increased to 3000 tons per day, permitting the mining of ore in the square-set area at a maximum rate not usually achieved, because of the scarcity of labor. Increased mill capacity also permits block caving and the mining of jig tailings at variable rates to keep mill feed up to 3000 tons per day. Fortunately the three types of feed are amenable to the same mill circuit and reagents for recovery of Pb and Zn. For example, during the first 10 months of 1952 square sets produced 827 tons per day, block-caving 1421 tons per day, and jig tailings 643 tons per day, an average daily production of 2891 tons for all three products. Exploration had proved the existence of an ore-body 1000 ft long and 165 ft wide in horizontal section, see Fig. 1. Company engineers were concerned only with the vertical extension, about 300 ft, from an old level to the surface. Much of this almost outcropped, Fig. 2. The ore lies in the hanging wall of a major fault of the Bunker Hill mine, standing at 65" in one end of the zone and separated from the fault by a wedge of waste, see Fig. 3. This wedge pinches out near the center of the zone, at which point the ore dips 45", lying nearly on the fault, Fig. 4. The remaining portion lies on the fault and conforms to the fault dip of 35", Fig. 5. Open-pit mining for the top of the ore was considered, but since the ore zone dipped into and under the mountains, adverse waste-to-ore ratios precluded use of this method. The ore occurs in massive quartzite of sufficient strength to support untimbered drifts, crosscuts, and raises. Zones of weakness in the quartzite are bedding, jointing, and small faults or slips. The mineralization, which occurs as small stringers of sphalerite and galena as well as pyrite, creates another line of weakness. The mineral veins or veinlets in themselves are high-grade. Their size and regularity and the amount of barren quartzite by which they are separated determined the limits of mineable ore, which are all assay limits except for the one determined by the major fault. Block 1 Without any background of caving in this type of quartzite, engineers selected the first block on the very steep end of the zone. Compelling reasons prompted this decision. The steep portion of the ore in Block 1 was of the lowest grade, so that if difficulties were encountered no very valuable ore would be lost, while the experience gained might be applied in mining the remaining blocks. A block 200x200 ft was laid out, with four scrams spaced 50 ft apart for drawing and placed at a right angle to the strike. Finger raises were placed in a 25-ft interval grid pattern, with flat undercutting done by crosscuts at the undercut level 25 ft above

Jan 1, 1954