Search Documents

By Harry M. Mikami, A. Gene Sidler

Chemistry of the evolution of materials in contact with copper converter tuyeres is delineated by means of analyses of periodic punch rod samples taken during a converter cycle. Lining samples from known peripheral and end locations from three converters were investigated chemically and petrographically. One set of eight specimens representative of all lining parts was removed for study before completion of the campaign. Purely surface removal by slag action is minor. Slag filling of interconnecting cracks extending to the hot face results in a "stoping'' action which shapes the hot face contour and is a significant factor. Major wear mechanism is believed to be copper metal slabbbing caused by metal first penetrating joins and invading fractures or impregnating brick structure laterally from the joints. Importance of lining design and joint fit are emphasized. New laboratory tests are indicated. In the copper converter, molten matte, which is essentially a solution of iron and copper sulfides, is blown with air to produce blister copper. During the first stage of the process the FeS component is oxidized to SOz and FeO, the latter combining with a siliceous flux to form a predominantly ferrous silicate slag. Successive increments of matte and flux are charged, blown, and skimmed of slag until sufficient CuzS ("white metal") has accumulated. This white metal is then blown to copper metal in the final or blister-forming stage by the oxidation of sulfur to SOz and the reduction of combined copper to metal. The reactions of both stages are exothermic so provide the required heat. Temperature is controlled by cold scrap copper, flue dusts, smelter reverts, and so forth. Considerable vari- ation in practices occur depending on the type of converter, grades of the matte and flu, and other factors. Lathe and Hodnett's' survey of world converter practices gives much information on these variations and their effects on the refractories. Principles of converting chemistry are presented by Newton and wilson,' Ruddle,' and schuhmann. Most copper converting occurs within the temperature range 2100" to 2370°F although individual smelters report1 ranges from as low as 1700" to 2240°F to a high of 2200" to 2400°F. Temperature intervals reported from beginning to end of blow varied from 45" to 540°F. Average temperature range was 2030" to 2260°F and the average interval 250°F During the matte-blowing stage varying amounts of magnetite (FeO.Fe,O,) are formed in the slag as suspended crystals and also the liquid portion of the slag will contain, in addition to ferrous silicate, some Fe20s which adds to the potential magnetite formation if the temperature falls. This is a component of the so-called "dissolved magnetite" often referred to in the literature. Although the slag may contain minor amounts of CaO, A1209, MgO, and alkalies, the principal components are Fe0-Fez03-SiO,. The phase equilibria relationships of this system have been elucidated by Muan~ and Schuhmann, et a1.' These data and estimates of converting atmospheres by schuhmann4 are useful tools in studying slag behavior. It would appear that in many cases reported magnetite contents of slags are apparently higher than actually is present at operating temperature. This is probably because much of it is formed during slag solidification. The quaternary systems which have Mg-0,1,0,' and addition to iron oxides and silica are also of interest in considering the reactions of the slags with basic refractories. The formation of magnetite has an important interrelationship throughout the pyrometallurgy of copper (Mossman,' Gronningsater and Drummond," Ruddle,' Elwood and Henderson") but its presence in the converter particularly relates to operating efficiency and lining life in certain instances. Archi-

Jan 1, 1963

By E. Topanelian

In recent years considerable progress has been made in the development and application of mathematical techniques for the solution of certain problems involving economic "strategies". Such a problem might involve, for example, the scheduling of shipments of a commodity from a number of sources to a number of destinations. The object would be to schedule the shipments in a manner so as to satisfy the destination requirements and at the same time minimize the transportation costs. The solution to such a problem is not necessarily intuitively obvious. The "obvious" solution is frequently far from optimum. If the shipments are to be made from, for example, only two sources to four destinations, the optimum schedule is readily found. However, if shipments are to be made from, say, 10 sources to several hundred destinations, even a competent and experienced scheduler may spend considerable time in finding a reasonable answer. Even then he is not sure that he has the optimum solution. Furthermore, he has no way of knowing how far from optimum the answer is. Consequently, he does not know whether he should accept this solution or seek a better one. Prior to the advent of large high-speed digital computers, little more could be done with such problems because of their great size and multiplicity of possible solutions. A problem involving 20 sources and 50 destinations would require choosing, from a very large number of possible combinations, the optimum combination of 1,000 variables. The best one could do was to utilize intuition, extrapolation from past experience, and other non-exact approaches. With a high-speed computer, however, such problems can be solved providing a reasonable computational procedure (or algorithm) can be utilized. The purpose of this paper is to describe such a procedure (linear programming) and to apply this procedure to a production scheduling problem. THE RESERVOIR PROBLEM A simple reservoir model is used throughout this analysis to illustrate the use of linear programming. Even the simplest reservoir behavior problem is nonlinear in both space and time, but if the geometry is fixed for a particular study and the time variable is quantized, the resultant system may be described by linear constraints on the variable production rates. Crude oil is available from five separate sources and is delivered to a pipeline. Sources 1, 2, 3 and 4 are ideal reservoirs and therefore are subjected to reservoir flow restrictions. Source 5 is labeled "Outside Source" and crude oil from this source is assumed to be available in unlimited quantities without considering reservoir conditions. The general problem is to determine the schedule of crude oil production from five sources which, over an eight-year period and subject to certain restrictions, will result in maximum profit. "Profit" is defined to encompass all economic factors and expenses involved in producing and selling crude oil to a pipeline facility. Such economic factors are lumped to the extent that the term represents the dollars profit from one barrel of crude oil from any of the five sources entering the pipeline system. Table 1 presents the assumed profit per barrel for oil from any of the five sources over each of the four time periods. In this chart the eight years is broken into four equal intervals of two years. The selection of four time periods of two years each and the values representing the potential profit are completely arbitrary selections for the purpose of illustrating this idealized reservoir problem. In any practical application of this work a careful economic study would have to be made in order to estimate potential unit profits for time periods as far in the future as eight years. In this particular study it is assumed that all of the potential unit profits (C) are known and fixed before the production schedule is attempted. For each reservoir arbitrary values are assigned for

By V. Patarini, M. Salkind

BECAUSE of its high strength and stiffness coupled with low density, continuous boron filament is showing great promise as a potential reinforcement for both metals and nonmetals. Of primary consideration for structural applications is the fatigue behavior of boron fiber composites. Composite fatigue behavior is dependent upon three factors: 1) fiber fatigue behavior, 2) matrix fatigue behavior, and 3) the effect of the interface and fiber ends. The purpose of this note is to describe the behavior of boron filament in rotating beam fatigue. The filament, described by Talley' and Galasso, Salkind, Kuehl, and Patarini,' was made by the hydrogen reduction of boron trichloride on a hot tungsten filament. Testing was performed using a commercial rotating beam wire fatigue tester* described by Votta.~ One end of the test sample is held in a chuck in a synchronous motor. The sample is bent around in a "U" shape, and the other end inserted into a carbide bushing. The maximum strain occurs at the bottom of the "U" where the radius of curvature is a minimum. The strain is adjusted by adjusting the length of the specimen and the location of the bushing. Samples were rotated at 3600 rpm and an automatic shutoff device used to determine the number of cycles to failure. The measurements were accurate to the nearest 360 cycles. The fatigue behavior is summarized in Fig. 1 for fifty-one samples of 4.8 x 10"3 in. diam fibers and ten samples of 3.2 X 10"3 in. diam fiber. The two sample groups represent two different filament production runs and two different nominal size groups. Both groups exhibited nominal tensile strengths of 400,000 psi. No significant difference in the fatigue behavior of the two sample groups is apparent. The scatter in the data is not unexpected for a brittle filament which exhibits a tensile strength distribution with a standard deviation of 10 to 15 pct. Because the test procedure provides a known outer fiber strain in the sample, the maximum stress was calculated assuming a Young's modulus of 58 x 10' psi. This value was selected as being representative of several nominal fiber sizes.2 All of the samples which failed exhibited sudden, catastrophic fracture, and no permanent deformation. One sample was stopped after 1.66 x lo8 cycles at *200,000 psi. The fiber exhibited no apparent damage or deformation. It is apparent that the fatigue resistance of boron filament is quite good. It can therefore be speculated that the fatigue behavior of boron fiber composites would be controlled by the "weaker links", namely matrix fatigue resistance and interface behavior. In fact, preliminary investigations have revealed that this is true for boron-reinforced aluminum? It should be noted that the data presented herein may not necessarily reflect the tensile fatigue behavior of boron filament. It is well-known that boron filament has a radial residual stress pattern with the outer surface in ~om~ression.~ Because of this fact, tensile failure is normally nucleated in the interior of the filament.5 Since the data presented herein is for a rotating beam test in which only the outer surface of the fiber is stressed to the maximum value, it would be incorrect to assume that the failure mechanism and fatigue behavior would be the same if the fiber were tested in tensile fatigue. The fact that many of the data are well above the nominal 400,000 psi tensile strength would tend to support this argument. The authors would like to express their appreciation to the United Aircraft Research Laboratories for supporting this investigation and for permission to publish the results. A portion of this effort was supported by the Air Force Materials Laboratory under contract AF33(615)-2125.

Jan 1, 1968

By W. S. Hyler, W. L. Bruckart

The powder metallurgy and arc-cast types of wrought molybdenum stock were studied in rotating beam fatigue. Endurance ratios of unnotched specimens after 5x10 cycles were found to be 0.74 and 0.81, respectively. Fatigue notch factors (K,) of 1.36 and 2.05, respectively, were obtained on V-notched specimens having a theoretical stress-concentration factor Kt = 3.1. MOLYBDENUM and its alloys are rapidly gaining importance as engineering materials of construction for high temperature applications. AS a wrought material, molybdenum and its alloys are outstanding above 1800°F. It is necessary, however, with molybdenum to provide elevated temperature oxidation protection. This is currently being studied by a number of investigators. Thus far, there have been no published data on the fatigue behavior of molybdenum either at room temperature or at elevated temperature. The knowledge of fatigue behavior, particularly notched fatigue behavior, becomes increasingly important as the engineering importance of a material increases, especially from the design standpoint. The work described here was directed toward determination of the notched and unnotched rotating beam fatigue characteristics of molybdenum at room temperature. Also, it was desired to learn whether any difference exists between wrought molybdenum of the powder metallurgy and the are-cast types. Fabrication History of Bar Stock For this work, bar stock was procured from Climax Molybdenum Co. (are-cast type) and from Westing-house Electric Corp. (powder metallurgy type). The processing histories of these materials are listed in Table I. The first lot of are-cast molybdenum was deoxidized by aluminum additions. The second lot was deoxidized by carbon." Both lots of the powder Microstructure A microscopic examination of these materials, as received, revealed the powder metallurgy molybdenum to be free of inclusions and to be finely fibered. On the other hand, the are-cast C molybdenum possessed numerous carbide inclusions, and the arc-cast A appeared to have coarse grained fibers. These are shown in Fig. 1. Owing to the large apparent difference in fineness of fiber between the are-cast A and the powder product and are-cast C, a check was made of the recrystallized grain sizes to determine whether these differences persisted. A series of recrystallization anneals revealed mixed grain sizes in both the are-cast A and the powder product. Variations in grain diameter of as much as 50 times were found after full recrystallization at 1200°C for 30 min. There was no distinction between the two. Arc-cast C was not checked. Room Temperature Mechanical Properties Prior to subjecting the materials to fatigue tests, room temperature mechanical properties were determined. These data, together with the tensil: strength of the notched bars, data,togetherare listed in Table tensil: There were no significant differences in the tensile strengths of the two types of molybdenum. However, the powder metallurgy material was generally more ductile and yielded at a somewhat lower stress than the arc-cast material. Tensile strengths of the notched specimens indicated a slightly greater notch strengthening effect in the are-cast C than in the powder product, lot 2. Room Temperature Fatigue Properties Sample Preparation: Specimens were prepared for use in R. R. Moore rotating beam fatigue machines. These specimens had a continuous radius test section with a minimum diameter of 0.260 in. The specimens were prepared by grinding to shape and polishing to produce a smooth unworked surface. Polishing consisted of rotating a disk in the continuous radius section on which were attached, successively, emery belts of 240, 400, and 600 grit. The specimens were slowly rotated during the operation. The belt speed was high, and rotation was such that polishing scratches were longitudinal. Unnotched Fatigue Properties: Unnotched fatigue data were obtained from a number of specimens of each of the four lots of molybdenum. The results of the tests are presented in Fig. 2. From this figure,

Jan 1, 1956

By F. W. Jessen, C. A. Johnson

The effect of treatment with ferrochrome lignosul-fonate on both sodium and calcium bentonites has been examined. In the early stages of treatment it appears that some base exchange of iron and chromium for sodium may occur with the sodium bentonite. Such exchange appears specific for exchange of sodium ions when the calcium ion concentration represents 40-5.5 per cent of the total exchangeable cations, and when additions of lignosulfonate are less than 1 lb per bbl. Adsorption appears entirely physical above 1 lb per bbl treatment level for all concentrations of calcium studied. Gel strength and plastic viscosity of both calcium and sodium bentonite systems were reduced with treatments of ferrochrome lignosulfonate up to 2 Ib per bbl, the greatest reduction occurring within a range of calcium concentration of 40-5.5 per cent of the total exchange capacity of the clay. INTRODUCTION The problem of control of viscosity and gel strength of drilling fluids by the action of thinners or dispersants has been studied by many investigators.1-7 In addition, much work has been done on formation of gel structure in clay suspensions. However, gel formation and structure still are incompletely understood, and the use of the various dispersing chemicals is based, to a large extent, on data almost entirely empirical in nature. In recent years the lignosulfonates have become increasingly important in the treatment and control of drilling fluids. More specifically, ferrochrome lignosulfonate has found rather wide acceptance, particularly in calcium systems.5-7 Lignosulfonates are refined lignin products made from spent sulfite liquor from which the fermentable sugars have been removed.15 The exact structure of lignin is not known; however, it is believed to be a phenolic propane type polymer which may exist as a branched chain or cross linked structure. The molecular weights of lignosulfonates probably range from 300 to 100,000 or more.15 A better understanding of the mechanism of adsorption of dispersants is essential before improvement and development of characteristics of drilling fluids and drilling fluid control is possible. This investigation was undertaken to determine the action of ferrochrome lignosulfonate on sodium and calcium montmOrillonite' LABORATORY INVESTIGATION A Stormer viscosimeter and Fann V-G meter were used to measure viscosity and gel strength. A Zeiss spectrophotometer was used for analysis of Fe and Cr and the flame attachment was employed in the analysis of Na, Ca and Mg. A General Electric X-ray diffraction unit utilizing Copper Ka radiation and a Ni-filter was utilized in the X-ray studies. PROCEDURE Two systems were studied. Predominately sodium clay, obtained from Wyoming, and a predominately calcium clay from Texas were used. These particular samples were chosen because of the extensive work of characterization completed by Mungan. Ionic base exchange capacity determined by flame photometry and total exchange capacity by the Kjehldahl method were obtained experimentally. A 7-per cent suspension of the sodium clay and a 20-per cent suspension of the calcium clay in distilled water were prepared by mixing with a high-speed mixer. The suspensions were allowed to stand for two weeks for complete hydration. Calcium chloride was added to portions of the sodium and calcium cla suspensions to obtain suspensions varying in Ca++ concentration as shown in Table I. A series of treatments was run with 500-ml portions of the original suspensions using a ferrochrome lignosulfonate. Treatment was carried out in the same way with each of the suspensions of varying Ca concentration. Viscosity and gel strength were measured and a filtrate obtained at each treatment level. Ten ml of filtrate were diluted to 50 ml, and aliquot portions of the 50 ml were taken for the Na, Ca, and Mg analysis by the flame photometer. The pH of these filtrates ranged from 7 to 7.3. Standard

By Pablo Hadzeriga

Great Salt Lake brine was subjected, in laboratory scale, to conditions simulating solar evaporation. Solid phases and the variation in composition of the liquid phase throughout the potassium salts crystallization zone are presented. These experimental results are discussed and compare with stable equilibrium data of the quinary system Cl-, SO4, Na+, K+, Mg + + and H2O. The Great Salt Lake brine in Utah is a vast reserve of several potential chemicals which has attracted much attention in the recent past. From the standpoint of an ore reserve, it may be said that the lake contains a low grade ore which has to be concentrated by evaporation of water. Because of the fairly favorable weather conditions in the Great Salt Lake area, it seems reasonable to consider solar evaporation as an economical means of concentration. From the view of phase chemistry, the main constituents of Great Salt Lake brine make it belong to the five component system: C1-, SO4=, Na+, K+, Mg++ and H2O. Because of their low concentration, the presence of other elements may be regarded as having little effect on the equilibrium of the five main components. Equilibrium data for the quinary system of our interest has been available for many years. Using these data, it is possible to calculate how the brine of the lake will concentrate when subjected to solar evaporation. In practicing solar evaporation, the weather factor and supersaturation conditions cannot be ignored, but their introduction into calculations using equilibrium diagrams is almost an impossible task. With the experimental work presented in this paper, an attempt is made to compare the stable equilibrium data of the quinary system as applied to the case of the Great Salt Lake brine and the dynamic equilibrium when that brine is subjected to continuous solar evaporation. Sea water brine belongs to this quinary system when only the major constituents are considered. The study of this system has been carried on since the last decades of the nineteenth century. The reason for these intensive studies was to give a geological explanation to the underground potash deposits. AS a result, many theories were presented trying to relate the equilibrium data with the geological formation, paragenesis and metamorphism of these deposits. Two main approaches were followed for the equilibrium studies of this quinary system. One of them, and the best known to us, was the school started in Germany in the last century by J. H. Van't Hoff. The other one, which started about the same time, was the school of N. S. Kurnakov in Russia. Both approaches were different and as a consequence generated opposite theories about the geological formation of potash deposits. The Van't Hoff school studied the quinary system of sea water under careful laboratory control, resulting in stable phase diagrams. During these studies, Van't Hoff recognized the difficulties in crystallizing some double salts.' ". . . . we unexpectedly found that some compounds whose formation in the solutions under investigation was possible at 25°C, nevertheless totally failed to put in an appearance. These, not to mention the calcium salts, were leonite, MgSO4 . K2SO4 4 H2O; kainite, KC1-MgSO4 . 3 H2O; and kieserite, MgSO4 .H2O. Even exceedingly slow crystallization with the addition of the compounds themselves did not remove the condition of supersaturation in the case of these bodies." However, those salts (leonite, kainite, and kieserite) were included in the stable phase diagram at 25°C as shown in Fig. 1 using D'Ans data.3 The figure also shows the sequence of crystallization of the Great Salt Lake brine according to the stable diagram. In later studies by the Van't Hoff school, especially by D'Ans,3 Karsten,4 Autenrieth,5,6 attention

Jan 1, 1968

By W. C. Ellis

IN an ingot of germanium solidified progressively from the bottom by a method' devised by J. H. Scaff and H. C. Theuerer, examination discloses ex- IH. C. Torrey and C. A. Whitmer, Crystal Rectifiers. p. 364. 1948. New York. McGraw-Hill Pub. Co. tensive twin relationships. A slice taken about midway in a cylindrical ingot approximately 3/4 in. in diameter and 1 1/2 in. in length, after etching and polishing to delineate different orientations, is shown in fig. la. The orientations of the regions designated with letters were determined by Laue X-ray back-reflection methods and plotted on stereograms. The orientation relationships of the designated components were determined by comparing the values for the nine angles between the three respective cube poles of each orientation with the values calculated in a formal treatment of octahedral multiple twinning in cubic crystals. Germanium, diamond cubic in structure, has the octahedral twinning habit. I am indebted to K. H. Storks for the calculation of the angular relationships of cube poles in octahedral twinning to four orders. The set of values for the nine angles is distinctive of the order of twinning. Confirmation for a multiple twin relationship is obtained from the determined indices of the mirror planes. These exist for all orders of twinning through the third and for some of the fourth." If the orientations are not those for twinning, then the nine angles for the cube poles do not correspond in value and distribution to those formally calculated. Since all nine angles must correspond in values and distribution of values to the calculated ones, the Laue method with a precision of one or two degrees is adequate to establish or deny with confidence the existence of multiple twins. Regions of the same orientation can also frequently be identified by the optical reflections. For example, the narrow twin bands in A at 2: 00 o'clock have orientation B1. The interesting twin relationships shown schematically in fig. lb were found for the section in fig. la. Most of this slice was made up of orientation, A, appearing in widely separated regions. Of the four possible first order twins of A, three were present in this slice and are designated by B with subscripts. Four second order twins of A are designated by C with subscripts. It is worth emphasizing that two of these, C, and C,, are second orders of A through the first order missing in this section. Two regions, designated by D with subscripts are third order twins of A. D2 is a sixth order twin of D,. All orientations found were ascribable to multiple twinning, as if the orientations in this section originated earlier in solidification from a single nucleus. The presence of extensive multiple twinning to- gether with the absence of other orientations appears to be a characteristic result in many instances of solidification of germanium. Fertile conditions for twinning probably exist in the array of atoms in the diamond cubic structure. The high order twins in the section shown, it is reasonable to presume, are the result of progressive octahedral twinning through several generations in the material freezing earlier. Some of these generations do not appear in this section, it is suggested, because their orientations with respect to the growth direction were unfavorable for survival. The extensive twinning is probably promoted during solidification by constraint imposed by volume increase, and to an irregular growth front. Twinning may also be due, in part, to the attempt of the solidifying region to attain the orientation most favorable to the growth direction (maximum thermal gradient). The nucleus for a twinned orientation could have its origin in a "stacking fault" on the close-packed octahedral plane. Further work is being done in which the course of twinning throughout an ingot is being studied. The results appear to be important in the general theory of solidification.

Jan 1, 1951

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

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

Jan 1, 1970

By H. H. Podgurski, J. C. M. Li, Y. T. Chou, F. N. Davis, R. A. Oriani

When an Fe-2 pct A1 alloy is nitrogemted at 500ºC with a gus tnixture (NH3-H2) in which the nitrogen activity has been kept Lou] enough to avoid the formation of iron nitride, a two-phase alloy is generuled which consists of AlN particles and a ferrite phase cotaining a heavy network of dislocations. The amount of nitrogen contained in such an alloy, when equilibrated with the nitrogenating atmosphere, far exceeds both that needed to satisfy the normal solution requirements of a Fe and that needed to convert all of the aluninuwi to AlN. This excess nitrogen is accounted for as being trapped on dislocations, adsorbed at the ferrite -AlN interface, and as an en-Iuznced lattice solubility in strained ferrite. This excessive uptake of nitrogen had previously been attribuled by other investigators to the formation of a nonstoichiornetric aluminum nitride. Isotope exchange experiments revealed various amomts of exchargeable N14 present in the originally nitrided samples that could not be removed by reduction with HS at 500ºC. This exchangeable nitrogen has been identified us that bound to the AlN -ferrite interface. Estimates of inter facial areas in alloys containing -3 pct by weight of A1N are as high as 10 sq m per g of alloy. ThE first1 of this series of papers described the experiments forming the basis for the elucidation of the mechanism of the formation of aluminum nitride particles within an Fe-A1 alloy. It was found that not only are dislocations necessary for the nucleation of the AlN particles but also the nitriding reaction in turn produces a dense network of dislocations in the ferrite matrix. It was also observed that nitrogen in excess of that needed for the formation of stoichiometric AIN is taken up by the alloy without the formation of an iron nitride. The present paper is an analysis of the excess nitrogen sorbed by the nitrided Fe-A1 alloy which considers the structure generated by the formation of the aluminum nitride particles. Because of the high density of dislocations, this system has proved to be quite useful in studying nitrogen-dislocation interactions. Wriedt and Darken2 have already reported such studies in a cold-worked ferritic steel. EXPERIMENTAL Nitrogen Sorption. The specimens of this alloy were cold worked (50 pct reduction) to 0.011 in. thickness and chemically cleaned in a 2:1 concentrated phosphoric acid-50 pct hydrogen peroxide solution before nitrogenation. The flowing nitrogenating atmosphere (11 pct NH3-89 pct H2) was established before the ni- trogenating temperature was reached. The same gravimetric and gas-flow equipment described in an earlier paper1 was also used in this investigation. Changes in nitrogen concentration were followed gravimetrically when establishing the isotherms. In the isotope exchange experiments, concentration changes were followed volumetrically. In some instances chemical analyses (Kjeldahl method) were used to check for material balances in both the gravimetric and volumetric procedures. Our objective was to obtain reversible nitrogen sorption isotherms for alloys equilibrated with NH3-H2 gas mixtures over a large range of nitrogen activity* and temperature. The *Defined as equal to PN H /P3/2 ,where P corresponds to partial pressure in atmospheres. Actually the nitrogen activity, aN, in the alloy equals K PNH3 /p3/2H2, where K is the equilibrium constant for the reaction NH3 = N + 3/2H2. upper limit for nitrogen activity was below that which would produce iron nitride; for reasons which will become apparent later, most of the sorption studies were made in the temperature range between 400" and 500'C. The alloy sample studied most extensively in this investigation was given a series of successive reductions (100 pct H2) and nitrogenating treatments at 500°C to attain a stabilized structure. Presumably some dislocations were lost during these treatments. Throughout most of the sorption studies, temperature was held at ± 1°C and the gas-phase composition was held to k0.2 pet NH3. Based upon the results of numerous diffusion experiments with this alloy* the 'Results to be published in a third paper of this series. times chosen for equilibration were considered more than adequate, Nitrogen Isotope Exchange. The first exchange experiments were carried out by circulating a measured quantity of H2 and NH3* (with a predetermined isotopic *The NH3 was synthesized over a synthetic ammonia iron catalyst using H2, and N2, enriched with N15. AS the NH3 was formed it was removed continuously from the gas phase by circulating the mixture through a refrigerated (78ºK) trap. When most of the nitrogen had been converted to NH3, it was distilled from the trap into a glass storage vessel. composition, N15/N14) over a nitrided specimen at 450°C in a closed glass system. Attempts to reach the exchange limit isothermally, i.e., an isotopic ratio (N15/N14) in the gas phase identical with the extractable nitrogen in the nitrided alloy, were futile. The exchange rate between the gas phase and the alloy was too slow, involving many days. To circumvent the slow exchange with the gas phase, measured amounts of N15 and N14 were introduced into the alloy by nitrogenating with an NH3-H2, mixture at 500°C containing an N15/N14 ratio of 7.76; the charged specimens were then sealed by allowing an oxide film to form over them in air, and in this final condition the specimens were subjected to 500°C in vacuum for various times during which isotope exchange was allowed to proceed within the specimen. It was estab-

Jan 1, 1970

1. Healthy and active Local Section organizations are vital factors in promoting the vigor and growth of the Institute. 2. Activity on the part of Local Sections should be recognized and stimulated by appropriation of funds from the Institute's treasury; and these appropriations should be as. large as is consistent with the relative needs for other activities. 3. As between different Sections, the amount of such appropriations should be based primarily on the extent of activities as reflected in the number and character of meetings held and the attendance of the members at such meetings. 4. In making a request for funds for any year, the officers of a Local Section should submit a report on the printed form approved by the Directors at their meeting on November 19, 1937. 5. A standing Committee on Local Section Appropriations, consisting of one past Chairman of a Local Section, one member of the Institute's Executive Committee, and one member of the Finance Committee, shall be appointed by the President and shall pass upon requests for appropriations and authorize payments within bounds of the budget. The committee will be guided by the principles herein outlined, always having in mind the vital importance of healthy, active Sections to the, welfare of the Institute as a whole. 6. According to Article XI, Section 2 of the Bylaws, requests for appropriations shall be signed by the Chairman, Secretary and Treasurer of the Section. 7. Requests for appropriations must be in the hands of the Secretary of the Institute by February 15 of the year for which they are desired.

Jan 1, 1946

1. Healthy and active Local Section organizations are vital factors in promoting the vigor and growth of the Institute. 2. Activity on the part of Local Sections should be recognized and stimulated by appropriation of funds from the Institute's treasury; and these appropriations should be as large as is consistent with the relative needs for other activities. 3. As between different Sections, the amount of such appropriations should be based primarily on the extent of activities as reflected in the number and character of meetings held and the attendance of the members at such meetings. 4. In making a request for funds for any year, the officers of a Local Section should submit a report on the printed form approved by the Directors at their meeting on November 19, 1937. 5. A standing Committee on Local Section Appropriations, consisting of one past Chairman of a Local Section, one member of the Institute's Executive Committee, and one member of the Finance Committee, shall be appointed by the President and shall pass upon requests for appropriations and authorize payments within bounds of the budget. The committee will be guided by the principles herein outlined, always having in mind the vital importance of healthy, active Sections to the welfare of the Institute as a whole. 6: According to Article XI, Section 2 of the Bylaws, requests for appropriations shall be signed by the Chairman, Secretary and Treasurer of the Section. 7. Requests for appropriations must be in the hands of the Secretary of the Institute by February 15 of the year for which they are desired.

Jan 1, 1946

1. Healthy and active Local Section organizations are vital factors in promoting the vigor and growth of the Institute. 2. Activity on the part of Local Sections should be recognized and stimulated by appropriation of funds from the Institute's treasury; and these appropriations should be as large as is consistent with the relative needs for other activities. 3. As between different Sections, the amount of such appropriations should be based primarily on the extent of activities as reflected in the number and character of meetings held and " the attendance of the members at such meetings. 4. In making a request for funds for any year, the officers of a Local Section should submit a report on the printed form approved by the Directors at their meeting on November 19, 1937. 5. A standing Committee on Local Section Appropriations, consisting of one past chairman of a Local Section, one member of the Institute's Executive Committee, and one member of the Finance Committee, shall be appointed by the President and shall pass upon requests for appropriations and authorize payments within bounds of the budget. The committee will be guided by the principles herein outlined, always having in mind the vital importance of healthy, active Sections to the welfare of the Institute as a whole. 6. According to Article XI, Section 2 of the Bylaws, requests for appropriations shall be signed by the Chairman, Secretary and Treasurer of the Section. 7. Requests for appropriations must be in the hands of the Secretary of the Institute by February 15 of the year for which they are desired.

Jan 1, 1940

By G. R. Leverant, M. Gell

The high- and low-cycle fatigue poperties of MAR-M200 directionally -solidified into columnar-grained and single crystal forms were determined at 1400" and 1700°F. These results were compared with the corresponding properties of conventionally -cast MAR-M200. The low-cycle fatigue lives of the columnar-grained and single crystal materials were similar at both temperatures and were one to two orders of magnitude greater than those of conventionally-cast material. The variations in the fatigue lives among the three forms of MAR-M200 were related to the more rapid rate of intergranular muck propagation compared to that of transgranular propagation. In conventionally-cast MAR-M200, cracks were initiated in grain boundaries and crack popagation occurred rapidly along an almost continuous grain boundary path. In the columnar-grained material, crack initiation occurred on short transverse segments of grain boundaries, but crack propagation was transgranular. The fatigue lives of columnar-grained and single crystal materials were approximately the same because most of the life in both materials was spent in trans-granular propagation. For the directionally -solidified materials, the number of cycles to failure, Nf, can be related to the total strain range, , by: heT = K where n and K are 0.16 and 0.044 at 1400'F and 0.29and 0.098 at 1700, respectively. In addition to intergranular crack initiation in the columnar-grained material, initiation also occurred at we-cracked MC carbides and micropores in both directionally-solidified materials. At 1400°F, fatigue life was reduced with increasing MC carbide size, but at 1700 there was no effect of carbide size. THE creep and stress-rupture properties of conventionally-cast nickel-base superalloys can be greatly improved by directional solidification into either single crystal or columnar-grained forms. The improvement in properties results from a reduction in intergranular cavitation and crack growth in the columnar-grained materials and the complete absence of this fracture mode in the single crystals. This paper describes the effect of grain boundaries on the elevated temperature fatigue properties of the nickel-base superalloy MAR-M200. The effect of cycling frequency on cracking arid fatigue life and the role of MC carbides and micropores on crack initiation are also emphasized. The fatigue properties of columnar-grained and single crystal MAR-M200 at room tem- perature,4,5 and the change in the mode of fatigue crack propagation with temperature6 have recently been described. I) EXPERIMENTAL PROCEDURE The material used in this study was the nickel-base superalloy MAR-M200, directionally-solidified into columnar-grained and single crystal forms. The columnar grains were approximately 0.5 mm in diam. The nominal composition of these materials in wt pct was 0.15C, 9Cr, 12.5W, loco, 5A1. 2Ti, lCb, 0.05Zr. 0.015B, bal Ni. They were solutionized for 1 to 4 hr at 2250°F followed by aging at 1600°F for 32 hr. which resulted in 0.2 pct offset yield stresses of 150,000? 144,000, and 95,000 psi at room temperature? 1400°, and 1700°F, respectively. The corresponding elastic moduli parallel to the testing direction were 19.2. 15.0, and 12.5 x 106 psi, respectively. Specimen design, testing procedures and alloy mi-crostructure have been described previously and will only be summarized here. Following the 1600°F aging treatment. MAR-M200 contains an ordered, cuboidal, y' precipitate 0.3 1 on edge, which is coherent with the 1 matrix. The y' precipitate is quite stable; even after testing at 1700°F. the precipitate is only slightly enlarged and its corners somewhat rounded. The alloy also contains a small volume fraction of micropores, and MC carbides. some of which contain preexisting cracks5 formed during casting. These cracks are always parallel to the long dimension of the carbide. Measurement of MC carbide size has been described previously.5 Axial fatigue tests were conducted in air over a wide range of strain amplitudes in both the high - and low-cycle fatigue regions, with specimen lives varying from about 10' to 10' cycles. Low-cycle fatigue (LCF) tests were strain-controlled with strain varied between zero and a maximum tensile value at a frequency of about 2 cpm. High-cycle fatigue (HCF) tests were stress-controlled with the stress varied between 5000 psi and a maximum tensile value less than the yield stress at a frequency of either 10 cps or 0.033 cps (2 cpm). The temperature in the gage section was controlled to 52°F. Specimen axes were within 5 deg of the [001] growth axis of the single crystals and the common [001 ] growth axis of the columnar-grained material. Specimen gage sections were electro polished prior to testing. After the standard heat treatment, three specimens were coated with a typical aluminide coating applied as a slurry. An additional specimen was given the coating heat treatment without actually being coated. In all cases: specimens were reaged at 1600°F for 32 hr after receiving the coating heat treatment at 1975'F for 4 hr.

Jan 1, 1970

By Edwin R. Phelps, Charles W. Porterfield

BACKGROUND OF SURFACE MINING Surface mining refers to the process of removing the material (over- burden) overlying a coal seam and exposing the coal so that it can be loaded out and conveyed by trucks or other methods to the preparation plant or other facility. Surface mining has not always been important in the coal industry. In the early 1900s, almost all of the coal mined in the United States was mined by underground methods. In 1900, about 192 Mt (212 million st) of bituminous coal mere mined and less than 1% was mined by surface methods. The development and use of larger equipment has allowed surface mining to gain prominence throughout the years. Table 1 shows the total production of coal by mining method in the United States for ten-pear periods since 1920 and indicates the growth of surface-mined coal production. Surface mining will undoubtedly continue to account for a large percentage of the coal production in the US for many years because: 1) The capacity of surface mining excavators has continued to increase. Today, mining companies are using shovels (see Fig. 1) which are able to move up to 137.6 m3 (180 cu pd) in each bite and draglines (see Fig. 2) which move up to 168.2 m3 (220 cu pd) in each bucketful. 2) Increasing tonnage from the thick western coal seams is being produced by surface mining methods. 3) Surface mining has normally had lower costs and a better safety record than underground mining. 4) Surface mining normally recovers a much higher percentage of the coal reserve than can recovered by underground mining. 5) Some coal measures call best be extracted by surface mining

Jan 1, 1981

By C. Y. Clayton, Francis B. Foley, Muir L. Frey

DuRing the past year, we have investigated the cause of 88 per cent, of the failures by breakage near the bit end of some 1-in. hollow, hexagon, drill steel used in a metal mine. This breakage in the region of the bit end of the steel was peculiarly interesting because we have been Ied to believe that breakage is most prevalent at the shank end of drill steels near the place where the steel is gripped in the chuck of the machine. Records from the mine showed, also, that the breakage was much more frequent in the short lengths of large gage than in the longer steels; this is shown graphically in Fig. 1. Because the shorter lengths of steels are usually those that have been made from broken pieces of long steels or from steels that have worn down in service, rarely being made from new stock, those who are wont to suspect steel of tiring and crystallizing in its old age through fatigue are quite apt to see in this instance an argument in favor of their idea. As usual, a careful examination of these steels reveals defects of a character hardly to be overlooked in favor of such a cause. The steel in question was rolled with a sand core and was of the usual drill steel composition: Carbon 0.85 per cent., manganese 0.60 per cent., silicon 0.25 per cent., phosphorus 0.02 per cent., and sulfur 0.02 per cent., with the exception that in some specimens there was vanadium, not exceeding 0.20 per cent. The following lengths and gages were used: LenGth, GaGe, LenGth. GaGe, Feet Inches feet Inches Starter 2 % 7 111/16 3 2 % 8 11 4 2 % 9 1 9/16 5 2 10 1 7/16 ________6_____________115/16____________________________

Jan 1, 1924

By David B. Reger

The substantial expansion of previously discovered gas pools was the principal feature of petroleum activity in West Virginia during 1940. At least one new gas pool was discovered and various other successful wildcat completions may prove to be gas-pool openers. Some slight extensions of oil pools were also made. The new productive territory, principally gas, added by these extensions was approximately 33,800 acres. ' In general, oil activity was slight because of unfavorable crude prices. Gas activity, on the contrary, increased considerably, although the price of gas did not materially change. The account of operations, as gathered from trade journals and other reporting services, shows that 709 new wells were drilled, resulting in 102 new oil wells with I055 bbl. of daily new produc-tion; 468 new gas wells with 633>g47,000 cu. it. of daily open flow; and 139 dry holes. Also, 91 old wells were drilled to deeper sands, with 143 bbl. and 44,833,000 cu. ft. of added production. On the new wells the oil average was 10.34 bbl, per well per day; and the gas average was 1,354,000 cu. ft. per well per day. On new wells the ratio of dry holes to completions was 19.61 per cent. On deeper drilling to other sands the ratio of failures was 12.I per cent. From an exploratory standpoint, one strictly new gas pool (Lorentz) was opened in Upshur County. Little forecast of its extent or reserve can now be made. The new extensions of various other previously discovered pools, however, give assurance of a new gas reserve that will equal approximately a year of gas demand. In addition to these definite supplies two widely separated Oriskany sand (L. Dev.) wildcats in Jackson County, one of which was completed late in 1940 and the other early in 194.1, may indicate two separate pools or may greatly extend known pools. In south-ern Kanawha County, also, an old Oris-kany-sand well deepened to the White Clinton sand (Sil.) showed a volume of 733,000 cu. ft. and rock pressure of 1800 Ib., giving rather clear assurance that this deep sand, in which only slight quantities of gas had previously been found, should eventually supply much new gas. On the other hand, various deep tests to the Oriskany sand in Harrison, Putnam, Randolph and Wood Counties were totally dry or gave only small volumes of gas, The principal oil wells completed, by counties, were: Calhoun, 15; Clay, Ir; Pleasants, 14; Ritchie, 15; and Roane, 7. Production for the year was estimated by the U. S. Bureau of Mines as 3,444,000 bbl., as compared to 3,684,000 bbl. in 1939. The leading counties in gas-well completions were: Boone, 36; Braxton, 17; Cabell, 25; Calhoun, 16; Clay, 22; Gilm.er, 47; Jackson, 38; Kanatvha, 77; Lincoln, 18; Putnam, 32; IGtchie, 40; and Wayne, 31, Production for the year is estimated by me as I70,000,000,000 cu. ft. as compared to I59,226,000,000 cu. ft.* in 1939. No long pipe lines were built but various gas-line extensions and cross connections,

Jan 1, 1941

By David B. Reger

The substantial expansion of previously discovered gas pools was the principal feature of petroleum activity in West Virginia during 1940. At least one new gas pool was discovered and various other successful wildcat completions may prove to be gas-pool openers. Some slight extensions of oil pools were also made. The new productive territory, principally gas, added by these extensions was approximately 33,800 acres. ' In general, oil activity was slight because of unfavorable crude prices. Gas activity, on the contrary, increased considerably, although the price of gas did not materially change. The account of operations, as gathered from trade journals and other reporting services, shows that 709 new wells were drilled, resulting in 102 new oil wells with I055 bbl. of daily new produc-tion; 468 new gas wells with 633>g47,000 cu. it. of daily open flow; and 139 dry holes. Also, 91 old wells were drilled to deeper sands, with 143 bbl. and 44,833,000 cu. ft. of added production. On the new wells the oil average was 10.34 bbl, per well per day; and the gas average was 1,354,000 cu. ft. per well per day. On new wells the ratio of dry holes to completions was 19.61 per cent. On deeper drilling to other sands the ratio of failures was 12.I per cent. From an exploratory standpoint, one strictly new gas pool (Lorentz) was opened in Upshur County. Little forecast of its extent or reserve can now be made. The new extensions of various other previously discovered pools, however, give assurance of a new gas reserve that will equal approximately a year of gas demand. In addition to these definite supplies two widely separated Oriskany sand (L. Dev.) wildcats in Jackson County, one of which was completed late in 1940 and the other early in 194.1, may indicate two separate pools or may greatly extend known pools. In south-ern Kanawha County, also, an old Oris-kany-sand well deepened to the White Clinton sand (Sil.) showed a volume of 733,000 cu. ft. and rock pressure of 1800 Ib., giving rather clear assurance that this deep sand, in which only slight quantities of gas had previously been found, should eventually supply much new gas. On the other hand, various deep tests to the Oriskany sand in Harrison, Putnam, Randolph and Wood Counties were totally dry or gave only small volumes of gas, The principal oil wells completed, by counties, were: Calhoun, 15; Clay, Ir; Pleasants, 14; Ritchie, 15; and Roane, 7. Production for the year was estimated by the U. S. Bureau of Mines as 3,444,000 bbl., as compared to 3,684,000 bbl. in 1939. The leading counties in gas-well completions were: Boone, 36; Braxton, 17; Cabell, 25; Calhoun, 16; Clay, 22; Gilm.er, 47; Jackson, 38; Kanatvha, 77; Lincoln, 18; Putnam, 32; IGtchie, 40; and Wayne, 31, Production for the year is estimated by me as I70,000,000,000 cu. ft. as compared to I59,226,000,000 cu. ft.* in 1939. No long pipe lines were built but various gas-line extensions and cross connections,

Jan 1, 1941

By B. K. Larkin, H. K. van Poollen, H. C. Bixel

A detailed treatment is given of the transient pressure behavior of a well located near a linear discontinuity. On either side of the discontinuity, the values of permeability, viscosity, compressibility, and porosity are uniform, but may be different from those on the other side of the discontinuity. These results generalize previously published works which assumed the permeability ratio for media on different sides of the discontinuity was zero, one, or infinity. One application of this material would be to facilitate detection of facies changes or fluid-fluid contacts by transient testing. Solutions, presented graphically, show pressure decline for constant rate fluid production. The range of variables examined includes dimensionless time from 0.1 to 100, rnohility ratio from 0.001 to 1000 and specific compressibility ratio from 0.001 to 1000. For dimensionless tinze less than 0.4, the pressure behavior is essentially that of a well in an infinite reservoir. Thus, reservoir properties near the well may be estimated in the usual manner. Using an overlay technique to match an experimental curve with one of the theoretical curves, it is possible to estimate the distance to a discontinuity by substituting the actual time t and the corresponding dimensionless time , at which a match occurs into the equation where is the diffusivity near the well, and may be estimated from data taken at early time. Because of both the complexity of the solutions and limited computer facilities, well interference problems were not examined extensively. However, it was found that well interference may be masked by the discontinuity in some cases. By superposition of the results of constant rate fluid production, the problenz of pressure buildup may be treated. Such results show that for early shut-in times correct values for the transnzissibility are obtained from conventional semilog plotting. However, erroneous values of the static reservoir pressure are obtained unless data at large shut-in times are taken. INTRODUCTION Transient well testing has yielded estimates of such reservoir parameters as static reservoir pressure, permeability. porosity, and well bore effects. In most tests, it was assumed that the reservoirs were homogeneous and iso-tropic. Anisotropic media' and radial discontinuities were considered.'.' Various studies have been made on multiple-layer reservoirs." ' Linear discontinuities have been described for problems of one-dimensional flow.' In the present paper, a mathematical treatment is given for a well located near a linear discontinuity in an otherwise infinite medium (see Fig. 1). An actual reservoir analogy would be a well in a relatively thin reservoir near a fluid-fluid contact, or a well located in a reservoir exhibiting a sudden change in rock and formation characteristics, such as thickness, porosity, or permeability. A sudden change in porosity or permeability may be caused by clay fill or other types of facies changes. Sudden thickness changes niay be the result of such geological formations as buried shore lines and channel deposits. In otherwise uniform formations, a linear discontinuity may be caused by fluid-fluid interfaces such as oil-water contacts. 3s-oil contacts, or gas-water contacts.

By Northcutt Ely

International developments affecting foreign in- vestments in 1960-61 were many, varying from region to region and differing with respect to various categories of investments. Total value of U.S. private investment abroad in 1960 was approximately $32.7 billion, an increase of $2.9 billion over 1959. Production and distribution of mineral resources was, by a sizeable margin, the most important function of American capital working in foreign countries in 1960. Investment in mining or petroleum interests totaled approximately $14 billion, or 42% of all direct foreign investment. In- vestments by industry for 1960 were as follows: Petroleum-10.9 billions, Mining-3.0 billions, Manufacturing-11.2 billions, Utilities-2.5 billions, other-5.1 billions. American investors found Canada and Latin America to be most desirable in 1960 with the greatest percentage of American capital in all areas centered in the petroleum and mining industries. The areal breakdown of total American investments is as follows: Canada-$11.2 billions, Latin America-$8.4 billions, Western Europe-$6.6 billions, Middle East-$1.2 billions, Far East-$1.2 billions, Africa-$.9 billions, other areas-$3.2 billions.

Jan 3, 1962

J. T. Pullon, Rowangarth, Roundhay, Leeds, England :— In discussing Mr. Lee's paper, I wish to call attention to the fact that Mr. B. II. Thwaite (who was heard here yesterday on the subject of the application of blast-furnace gas for the production of power, of which he was undoubtedly the pioneer) read, at the Engineering Congress in Glasgow in 1901, a paper on the profitable utilization of power from blast-furnace gases,' in which he suggested the diversion and cleaning of the whole of the waste gases coming from the blast-furnace and their utilization for power-production, so as to obtain, with proper manipulation, from 4 to 6 times the efficiency of present methods. He suggested also the heating of the stoves with producer-gas of a higher and therefore more suitable calorific value, so as to maintain them in a constant state of maximum efficiency, free from dust, and to avoid the irregular working of the furnace, besides obtaining a maximum supply of air-blast, of 15 or even 20 lb. pressure, by means of internal-conibustion blast-engines driven by the cleaned waste furnace-gases, with a surplus of gas left for other uses. Since that time, in view of the necessity of having a stand-by plant, immediately available, in case of strikes or other reasons causing the banking or blowing-out of the blast-furnace, he has developed, as an addition to his other types of producer, a high blast-pressure gas-generator, producing a gas identical with, or somewhat superior to, blast-furnace gas; and in which all the ash of the fuel is turned into fluid slag, which is available for, the production of slagwool. The gas is a little richer in carbon monoxide than average blast-furnace waste gas, and has only from 1 to 3 per cent. of hydrogen. Fig. I, drawn from a photograph, shows a plant containing this generator, now in operation at Leeds. It is made in units of from 1,000 to 10,000 h.p. capacity for each vessel, and coupled,

Jan 1, 1907