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By A. C. Fieldner, F. H. Gibson, W. A. Selvig

A foRmer paper1 described in detail various methods of calculating coal analyses to obtain the composition and calorific value of the pure coal substance—that is, of the coal free from its mineral matter. The paper included a table showing calorific values of pure coal, as calculated from float-and-sink portions, by means of the Parr formula for "unit coal" and by the customary moisture-free and ash-free formula. A modification of the Parr formula was proposed, based on the assumption that one-half the sulfur present in Coal occurs as pyritic sulfur and one-half as organic sulfur. In the published discussion of the paper Cady gave a table of results on a large number of Illinois coals as obtained by the Parr formula and the proposed modification thereof. The results obtained by Cady indicate that the Parr formula applies better to Illinois coals than does the modified formula proposed by Fieldner and Selvig. The present paper gives results obtained by applying the modified Parr formula to the analyses of the float-and-sink portions of the coals shown in the former paper, and results obtained by applying the Parr formula, the modified Parr formula, and the simple moisture-free and ash-free formula to various coals of the United States ranging in sulfur content from less than 1 per cent to more than 4 per cent sulfur. A graphic method of estimating the calorific value of pure coal and determining the relation of the coal ash to the mineral matter of coal, as proposed by Stansfield and Sutherland,2 was applied to a number of coals, and the results are given herein. Testing Formulas with Float-and-sink Separations The former paper by Fieldner and Selvig gave heat values of pure coal of the float-and-sink portions of 21 coals, as calculated by the Parr formula

Jan 1, 1932

By Meissner, C. A.

THE tendency all over Europe, just as it is with us, is to go to the use of turbines for new construction or replacement of old steam or even gas engines. 'The lower construction cost and the lower operating cost, when they can have high steam temperatures and pressures, together with their efficiency, is the cause of this change to turbines, both high and low pressure. The present trend is to equip plants with modern, efficient steam boilers, turbines, etc., and gradually work into high-pressure superheated steam equipment to accomplish a saving. One company has just completed a 375 to 400 lb., 700 deg. superheated steam installation and turbo-blowers with this end in view. Some of our new steam plants are using 350 lb. working pressure.

Jan 1, 1928

Jan 1, 1928

By Charles M. Cooley

In these troubled times free enterprise is maintaining vital molybdenum output, while expanding plant, and bringing in new low grade ore reserves, at Climax, the world's largest known molybdenum deposit. Climax Molybdenum Co. is putting $25 million into additional surface plant facilities and other millions into underground development. The expansion program to be operating by 1954 includes a new mining level, crushing plant, 4000-ft conveyor, milling units, by-products plant, and housing for 198 families. Completion of this program and low grade plant will add 10,000 tons per day to present capacity and several million tons to ore reserves.

Jan 1, 1953

By C. W. Sherman, J. Chipman, H. I. Elvander

THE pronounced and usually deleterious effects of sulphur on all ferrous metals and the resultant necessity for its control in metallurgical processes have stimulated many investigations of the system iron-sulphur. The data required for thermodynamic study of the behavior of sulphur in molten iron and steel include the activity and free energy of the dissolved sulphur and its heat of solution. Such data are also of theoretical interest since there is all too little information available concerning solutions of nonmetallic solutes in metallic solvents. It was the purpose of this investigation to attack the problem very directly by a study of equilibrium at several temperatures in the reaction H2 (gas) + S = H2S (gas) [1] K1 = PH2S /PH2 as where the sulphur is present in the liquid iron in amounts up to several percent by weight. Such a method of attack is not new since several careful studies have already been reported. It is planned, however, to extend the study to other metallic solvents and particularly to determine the effects of the various alloying elements on the activity of sulphur in liquid iron. This paper presents the results on molten iron-sulphur alloys containing up to 4 pct sulphur in the temperature range 1530°-1730°C. Literature Review The significant researches on dilute molten solutions of sulphur in iron include those of Chipman

Jan 1, 1951

By L. H. Levenson, Charles S. Barrett

Numerous determinations1-' of the texture of cold-rolled polycrystalline iron, steel, and ferritic alloys have been made with good agreement among the various observers as to the principal features of the texture common to all, but there has been no adequate explanation of the texture in terms of, the behavior of individual grains. This study presents an explanation of the texture based on the observed rotation of single crystals when deformed in a manner similar to a grain in the aggregate, a method we have found useful in leading to a better understanding of compression and tension textures;8,9,10 in particular, the aim has been to determine experimentally the end orientations of rolled single crystals of iron. These are discussed in connection with the point of view of Weverl and of Boas and Schmid2 that the rolling texture is a simple compression texture (compression normal to the rolling plane) superimposed on a simple tension texture (tension in the rolling direction), and the point of view of Kurdjumow and Sachs3 that three ideal end orientations exist. Experimental Method The single crystals used were in the form of disks cut from a stock of crystalst pre- pared in this laboratory by a strain-anneal method from mild steel decarburized and purified in hydrogen, the details of which have been described elsewhere.11 To ensure maximum elongation in the rolling direction and to simulate approximately the rolling of a grain in an aggregate, lateral flow was constrained by placing each crystal in a close-fitting hole in a plate of copper or iron of equal thickness and rolling the plate and crystal together. About one-third of the crystals were rolled in a "sandwich" pack by adding top and bottom cover plates. The two-high mill used had 8-in. diameter rolls and was operated at 15 r.p.m. The initial diameter of the crystals was between 1/4 and 1/2 in., while the starting thickness varied from 0.031 to 0.376 in. With a single exception, which was rolled 63 per cent, the crystals were rolled to a final reduction in thickness of 82 to 97 per cent in 20 to 40 passes, alternately changing the sense of the rolling direction. The initial orientations of the crystals were determined either by X-ray back reflection12 or by optical reflectionl3 from etch pits; the mean final orientations were determined by X-ray Laue photograms using molybdenum, silver, or tungsten radiations, by optical reflection, and in many cases by both methods. Results Twenty-six crystals were studied. It was found that there were three typical be-

Jan 1, 1941

By Charles S. Barrett, L. H. Levenson

Numerous determinations1-' of the texture of cold-rolled polycrystalline iron, steel, and ferritic alloys have been made with good agreement among the various observers as to the principal features of the texture common to all, but there has been no adequate explanation of the texture in terms of, the behavior of individual grains. This study presents an explanation of the texture based on the observed rotation of single crystals when deformed in a manner similar to a grain in the aggregate, a method we have found useful in leading to a better understanding of compression and tension textures;8,9,10 in particular, the aim has been to determine experimentally the end orientations of rolled single crystals of iron. These are discussed in connection with the point of view of Weverl and of Boas and Schmid2 that the rolling texture is a simple compression texture (compression normal to the rolling plane) superimposed on a simple tension texture (tension in the rolling direction), and the point of view of Kurdjumow and Sachs3 that three ideal end orientations exist. Experimental Method The single crystals used were in the form of disks cut from a stock of crystalst pre- pared in this laboratory by a strain-anneal method from mild steel decarburized and purified in hydrogen, the details of which have been described elsewhere.11 To ensure maximum elongation in the rolling direction and to simulate approximately the rolling of a grain in an aggregate, lateral flow was constrained by placing each crystal in a close-fitting hole in a plate of copper or iron of equal thickness and rolling the plate and crystal together. About one-third of the crystals were rolled in a "sandwich" pack by adding top and bottom cover plates. The two-high mill used had 8-in. diameter rolls and was operated at 15 r.p.m. The initial diameter of the crystals was between 1/4 and 1/2 in., while the starting thickness varied from 0.031 to 0.376 in. With a single exception, which was rolled 63 per cent, the crystals were rolled to a final reduction in thickness of 82 to 97 per cent in 20 to 40 passes, alternately changing the sense of the rolling direction. The initial orientations of the crystals were determined either by X-ray back reflection12 or by optical reflectionl3 from etch pits; the mean final orientations were determined by X-ray Laue photograms using molybdenum, silver, or tungsten radiations, by optical reflection, and in many cases by both methods. Results Twenty-six crystals were studied. It was found that there were three typical be-

Jan 1, 1941

By George W. Maynard

IN the biographical notice of Thomas F. Witherbee, published in Bulletin No. 32, August, 1909 (p. xxv), it is said that ". he is believed to have been the first manager in America to use the chemical laboratory for the purpose of controlling the regular running of the blast-furnace." Since the year is not given, I cannot decide as. to Mr. Witherbee's priority; but the statement leads me to contribute a bit of history, showing an early departure from the "rule-of-thumb " blast-furnace work to the employment of a chemist. In the autumn of 1868 the department of mining and metallurgy was established at the Rensselaer Polytechnic Institute. In connection with the assay-department a laboratory was equipped for making general commercial analyses. In January, 1869, Alexander L. Holley, the manager and builder of the Bessemer plant at the Rensselaer Works of John A. Griswold & Co., the first plant erected in the United¬States under the Bessemer patents, began to send me samples of ore, pig-iron, and steel for analysis. Early in 1869 I was regularly retained as chemist for the Rensselaer Works; and while the laboratory was not located at the works, for all practical purposes it was the works-laboratory. The increase in work soon made it necessary for me to secure an assistant. I applied to Prof. Charles F. Chandler, who recommended Dr. August Wendel, who had been an assistant of Rammelsberg and had lately landed in New York. Dr. Wendel remained with me until 1873, when I left Troy. My leaving made necessary the erection of a laboratory at the Rensselaer Works, which, was done under my supervision, and Dr. Wendel was employed as chemist. During the period from 1868 to 1873 my work as consulting mining engineer frequently called me to the Lake Champlain

Nov 1, 1909

MEETING OF SAN FRANCISCO SECTION Twenty members were present at the meeting of the San Francisco Section, May 20, 1919. Chairman Bradley being in Alaska, vice-chairman, T. A. Rickard, presided. Prof. Frank H. Probert gave a short account of the activities of the governmental commission, consisting of himself, George S. Rice, and F. G. Cottrell, which recently visited Europe, and studied the coal, iron, salt, and chemical industries. When the work is finished reports will he issued. He gave a resume of the history of. the changes in nationality of Alsace-Lorraine and 'described the importance of the region for coal, iron, and potash. With the return of these provinces France will have an annual output of more iron ore than she has coke to smelt it with; hence, the importance of the Saar coal field. With these new mines France will take the predominant position in the iron and steel-industry formerly held by Germany. Many details were given of the devastated mines of France, and of their former value, production and the destruction that overtook them. Noteworthy is it that much of the damage was done as late as Oct. 28, 1918, for the express purpose of ruining the country industrially. The damaged area of the Valenciennes coal basin embraced twenty-four concessions, three were damaged by artillery bombardment, but have resumed operations since the' armistice, nine had their surface: equipment destroyed by battle, pillage, and sabotage, while twelve concessions at the eastern-end of-the field suffered from wilful, systematic destruction. Of the 285 shafts in the district, 172 were flooded either by: turning surface streams into them, or, by wrecking the cuvellage; thus, admitting water and quicksand from the water-bearing strata above the coal measures. Two hundred and thirty-five surface plants were damaged, many of them to such an extent that they must be scrapped. These properties gave employment to 135,000 men before the war and, even admitting the remote possibility of getting workmen, the terrible destruction and devastation makes housing and living a difficult problem. It will probably be from 3 to 5 years before the mines are drained and information obtained as to underground conditions; to attain the pre-war output may require from 12 to 15 years.

Jan 8, 1919

By P. B. Baxendell, R. Thomas

Work on the calculation of vertical two-phase flow gradients by Cia. Shell de Venezuela has been based mainly on the "energy-loss" method proposed by Poett-mann and Carpenter in 1952. The "energy-loss-factor" correlation proposed by Poettmann and Carpenter was based on relatively low-rate flow data. This correlation proved inapplicable to high-rate flow conditions. In an attempt to establish a satisfactory correlation for high rates, a series of experiments was carried out at rates up to 5,000 BID in Cia. Shell de Venezuela's La Paz field in Venezuela, using tubing strings fitted with electronic surface-recording pressure elements. As a result of these experiments a correlation between energy-loss factor and mass flow rate was established which is believed to be applicable to a wide range of conduit sizes and crude types at high flow rates (e.g., above 900 BID for 27/8-in. OD tubing). It is anticipated that the resulting gradient calculations will have an accuracy of the order of % 5 per cent. At lower flow rates the energy-loss factor cannot be considered as constant for any mass rate of flow, but varies with the free gas in place and the mixture velocity. No satisfactory correlating parameter was obtained. As a practical compromise for low flow rates, a modification of the curve proposed by Poettmann and Carpenter was used. In practice this was found to give gradient accuracies of approxirnately ± 10 per cent clown to flow rates as low as 300 B/D in 27/8-in. tubing. INTRODUCTION Production operations in Cia. Shell de Venezuela's light- and medium-crude fields are principally concerned with high-rate flowing or gas-lift wells. Under these conditions the analysis of well performance, the selection of production strings and the design of gas-lift installations are vitally dependent on an accurate knowledge of the pressure gradients involved in vertical two-phase flow. Initially, attempts were made to establish the gradients empirically as done by Gilbert,' but the results were not reliable due to scarcity of data over a full range of rates and gas-oil ratios. Several methods of calculation based on energy-balance considerations were attempted, but the computations were cumbersome and the results cliscouraging. In 1952 a paper was published by Poettmann and Carpenter' which proposed a new approach. Their method was also based on an energy-balance equation. but it was original in that no attempt was made to evaluate the various components making up the total energy losses. Instead, they proposed a form of analysis which assumed that all the significant energy losses for mutiphase flow could be correlated in a form similar to that of the Fanning equation for frictional 1osses in single-phase flow. They then derived an empirical relationship linking measurable field data with a factor which, when applied to the standard form of the Fanning equation, would enable the energy losses to be determined. The basic method was applied in Venezuela to the problem of annular flow gradients in the La Paz and Mara fields" This involved establishing a new energy-loss-factor correlation to cover high flow rates and, also, some adaptation of the method to permit mechanized calculation using punch-card machines. The final result was 1 set of gradient curves for La Paz and Mara conditions which proved to be surprisingly accurate. With the encouraging results of the annular flow calculations, several attempts were made to obtain a corresponding set of curves for tubing flow. Here, unfortunately, little progress could be made. The original correlation of Poettmann and Carpenter was based on rather 1imited data derived from low-rate observations in 23/8- and 27/8-in. OD tubing. It did not cover the higher range of production rates, and extrapolation proved unsuccessful. A new correlation covering high flow rates was required, but this proved to be extremely difficult to establish since tubing flow pressure measurements at high rates did not exist—due to the difficulty of running pressure bombs against high-velocity flow. The necessity for reliable tubing flow data increased with the development of the new concessions in Lake Maracaibo, where high-rate tubing flow from depths of 10,500 ft became routine. Thus. it was decided to set up a full-scale test to establish a reliable energy-loss factor for tubing flow conditions. A La. Paz field light-oil producer with a potential of approximately 12,000 B/D on annular flow was chosen. To obtain full pressure gradients, a special tubing string was installed which was equipped with electronic surface-recording pressure measuring devices,

By R. A. L. Black

Between March and June 1962, the privilege of holding a Carnegie Corporation Fellowship enabled R. A. L. Black to travel extensively in the northeastern and western U.S. and in Canada, seeing mining schools, mining research establishments and a cross-section of the American and Canadian mining industry. Visits were paid to 12 university mining schools, 7 research establishments and 19 mining operations. The author had previously spent two months in Britain in a similar manner and eventually returned to his home in South Africa after a short period studying mining problem in Australia. Thus, although the following remarks are mainly concerned with the educational problems of mining in North America, a comparison of impressions of American and Canadian conditions could be made with impressions gained from first-hand experience of other mining centers in the English-speaking world. The conclusion was reached that the problems and conditions of mining, research and mining education are very similar in all areas visited.

Jan 4, 1963

By Wheeler Davey

WHEN metals are subjected to mechanical working, such as rolling, one of the phenomena that take place is a movement of the crystals of the metal into a system or systems of orientation which bear an angular relation to the direction of working. In rolled metal the crystals may orient themselves with respect to the rolling plane or the rolling direction, or both. Direct evidence of the existence of preferred orientations in rolled metal has been obtained by numerous investigators from X-ray patterns of the rolled metal. Most of these workers used a monochromatic pinhole method. Where the degree of preference for a single orientation is high the monochromatic pinhole pattern may be interpreted by a geometrical calculation based on the angular relationships of the planes in the crystal and the diffraction arcs on the X-ray pattern. This process may be aided by the geometrical construction of the locus sphere (Langenkugel), and reflection circles of Polanyi,1 Polanyi and Weissenberg,2 and Mark and Weissenberg,3 and of the plane polar figures (flachenpolfigur) of Franz Wever.4 R. M. Bozorth5 solves X-ray patterns from metals having a single preferred orientation by means of a series of charts which when placed over the X-ray pattern give directly certain angular relationships, between the crystal planes and the surface of the specimen.

Jan 1, 1929

By Wheeler P. Davey

When metals are subjected to mechanical working, such as rolling, one of the phenomena that take place is a movement of the crystals of the metal into a system or systems of orientation which bear an angular relation to the direction of working. In rolled metal the crystals may orient themselves with respect to the rolling plane or the rolling direction, or both. Direct evidence of the existence of preferred orientations in rolled metal has been obtained by numerous investigators from X-ray patterns of the rolled metal. Most of these workers used a monochromatic pinhole method. Where the degree of preference for a single orientation is high the monochromatic pinhole pattern may be interpreted by a geometrical calculation based on the angular relationships of the planes in the crystal and the diffraction arcs on the X-ray pattern. This process may be aided by the geometrical construction of the locus sphere (Lagenkugel), and reflection circles of Polanyi,l Polanyi and Weissenberg,2 and Mark and Weissenberg,3 and of the plane polar figures (flachenpolfigur) of Franz Wever.4 R. M. Bozorth5 solves X-ray patterns from metals having a single preferred orientation by means of a series of charts which when placed over the X-ray pattern give directly certain angular relationships, between the crystal planes and the surface of the specimen.

Jan 1, 1930

By N. K. Chen, R. Maddin

Columbium single crystals were deformed in tension and compression. Reorientation by X-rays and stereographic projections of slip traces indicate that plane of slip may be considered as (110). The plastic behavior is shown to be quite similar to the deformation of molybdenum single crystals. STUDIES on the crystallography of the deformation process in body-centered cubic metals have been renewed recently with investigations of iron single crystals1-" and molybdenum single crystals.4 It is now apparent that too many exceptions to the rationalization based upon the ratio of absolute testing temperature to absolute melting point by Andrade5 exist to permit more serious discussion of this type of analysis. The considerations of resolved shear stress utilizing only planes of the type {ll0}, {112), and {123)³,6 permit analysis of the deformation only on the basis of those three types of planes. The suggestions made by Elam7 and by Greninger8 in which the slip process is envisioned as a composite slip on two nonparallel {110) planes can be illustrated schematically in Fig. 1. It may be seen that an unresolved trace on any plane containing a <111> direction may be accomplished by varying the number of atoms participating in the composite process. By further varying the number of atoms in each plane but keeping the ratio of participating atoms constant, jogs could be obtained in the traces and hence wavy slip lines could be produced. Vogel and Brick&apos; studied the behavior of a iron single crystals in which they suggest that the plane of glide is "non-crystallographic" and may be predicted from the intersection between the great circle joining the slip direction and specimen axis with the great circle whose zone axis is the slip direction. In a more recent investigation on iron single crystals, Steijn and Brick" suggest that the slip mechanism may be considered as made up of a type of composite slip occurring on {110} and {112} planes. Evidence for a possible composite nature of the slip process has been presented for the case of molybdenum in the form of analysis of asterism and specimen axis rotation." Definite proof of a composite slip process must, however, await good electron microscopic resolution of the individual traces making up the unresolved optical trace used in determining the acting slip plane. The present investigation was undertaken to study the behavior of columbium single crystals not only in tension but also in compression since the specimen axis migration should indicate the plane or planes of glide in the same manner that the specimen axis migration in tension indicates the direction of glide. The orientations of eleven crystals investigated are shown in Fig. 2. Specific orientations are missing (those in the vicinity of [Ill] and [001] and consequently the effect of orientation on the crystallography of deformation could not be considered. Experimental Procedure The 1/8 in. rods (7 in. long) were subjected to an axial tension in vacuo while at temperatures in the vicinity of 2000°C for 2 to 4 hr. This treatment resulted in large cylindrical grains (about ½ in. long) occupying the entire cross section. A number of these rods were used for the tension studies by observing the behavior of the individual grains. For the compression studies, single crystals approximately % in. long by 1/8 in. in diameter were cut from the rods; the ends were ground parallel. All specimens were polished electrolytically in a solution of 15 cc HF(48 pct) and 85 cc H2SO4 (concentrated) using a platinum cathode, a current density of 0.04 amp per sq cm and a temperature between 25" and 60°C.10 Orientations were obtained using a Laue back-reflection method (3 cm film to specimen distance) with a ½ mm collimator 9 cm long. For the compression specimens, a reference mark was scratched on one of the compression sur-

Jan 1, 1954

PROF RICHARD ÅKERMAN Stockholm, Sweden DR. FRANK DAWSON ADAMS Montreal, Canada PROF RICHARD BECK Friberg, Germany ANDREW CARNEGIR New York, N.Y. DR. JAMES DOUGLAS New York, N.Y. PROF HATON DE LA GOUPILLIERE Paris, France SIR ROBERT A. HADFEILD London, England PROF HANS HOFFER Leoben, Austria JAMES FURMAN HOEFER Leoben, England PROF HENRI LOUIS LE CHATELIER Paris France

Jan 1, 1917

By Albert Sauveur

The instrument about to be described meets so perfectly the special needs of the metal microscopist that there eeeme to be little doubt but its merits must be readily appreciated by those who have had any experience in the microscopical examination of metals. The Microscope-Stand.—The microscope-stand proper, Fig. 1, consists of a microscope-tube, provided with both coarse and fine adjustments of the best construction, and with a draw-tube, rigidly mounted on a bar supported at both ends on substantial and firm cast-iron legs. The height between the table and the under side of the supporting bar is 5 in. and the distance between the supporting legs 12 inches. This arrangement affords free space below the objective for the examination of large epecimens of metals, such as full rail-sections, without detracting in the least from the value of the

Jan 1, 1912

By W. H. Smith

IN connection with some recent work on the effect of impurities on the ductility of chromium, it appeared desirable to know the solid solubility of carbon in chromium. A literature survey indicated that this information was not available. Although considerable work has been done on the Cr-C phase diagram,&apos;.&apos; previous investigators have been more concerned with the structure and phase boundaries of the carbide phases than with the terminal solid solution. The phase diagram shown in Fig. 1 is taken from the work of Bloom and Grant&apos; and represents the most recent determination. As indicated by the dashed line, the a solid-solubility limit was not determined. Experimental Procedure Alloys of chromium were prepared from hydrogen-treated and vacuum-degassed electrolytic chromium plus spectrographic grade carbon. The oxygen and nitrogen content of the alloys was <0.002 pct. After melting, analysis of the alloys showed them to contain 0.02, 0.08, 0.15, and 0.55 pct C. Pieces of the alloys were heated in a protective atmosphere to various temperatures and then quenched after holding for a time sufficient to insure equilibrium. Microscopic examination of the as-quenched alloys for the presence of a second phase was used as a measure of the solubility limit. The heats were made in a multiple hearth arc-furnace using a zirconium-gettered static argon atmosphere. A zirconium melt was made before each Cr-C heat. Triple melting was used to insure ingot homogeneity as shown by microscopic examination. The alloys were prepared by adding portions of a 4.5 pct C-Cr master alloy to high purity chromium. The carbon contents listed previously were those obtained by analysis. The nitrogen and oxygen contents after arc melting were both <0.002 pct. Sections 1/8X1/4X1/2 in. were cut from the 100-g ingots and a hole drilled in one end in order to suspend the sample from a molybdenum wire. After the surface was carefully cleaned, a sample of each melt was hung in a mullite tube heated externally by a platinum resistance furnace connected to a vacuum system. The lower portion of the mullite tube was sealed to Pyrex and closed off several inches below the furnace. This was filled with sili-cone oil kept cold by circulating cold water around the outside of the Pyrex. Quenching into the oil bath was achieved by melting a fuse wire supporting the sample. It required about 4 sec for the sample to cool from 1400" to 600°C. This severity of quench was considered satisfactory to freeze-in the high temperature equilibrium. For tests made at temperatures of 900" to 1200°C, heating was done in vacuum; for tests above 1200°C, an argon atmosphere was used. The holding time employed ranged from 12 hr at 900°C to 6 hr at 1400°C. Experiments were performed at temperatures of 900°, 1000°, 1100°, 1200°, 1300°, and 1400°C. Microscopic examination for evidence of a second phase was done at X1500. Experimental Result The microstructures of a 0.08 pct C-Cr alloy as-cast and after quenching from 1300°C are shown in Figs. 2 and 3. A 0.15 pct C-Cr alloy quenched from 1300°C is shown in Fig. 4. The data obtained from the quenching experiments is shown graphically in Fig. 5. If the Van&apos;t Hoff equation is obeyed, a plot on a logarithmic scale of the mol fraction of solute vs the reciprocal of the absolute temperature should give a straight line. For dilute solutions the weight percentage can be substituted for the mol fraction without introducing any appreciable error. The Van&apos;t Hoff equation can then be written as where H is the heat of solution in calories per mol. The slope of the straight line on the log pct C vs 1/T plot gives the value of AH. Assuming that the Van&apos;t Hoff equation is obeyed, which is probably justified for the dilute solution of carbon in chromium, the heavy straight line shown on Fig. 5 represents the best fit of the data. This line was obtained as follows. On Fig. 5 the results of the microscopic examination of all alloys following quenching were plotted and designated as to whether one or two phases were seen. Below 1100°C all alloys showed a second phase on quenching. The heavy vertical lines shown in Fig. 5 therefore represent the possible range of the ter-

Jan 1, 1958

By Benjamin F. Tillson

THE past seven years, and 1937 in particular, have witnessed the return of New Jersey iron mining to a place of importance. Following the World War period, little mining was done for several reasons. The properties were operated by small merchant furnaces whose demand was not sufficiently large to warrant large-scale methods with their attendant low operating costs. Under those conditions, the ore produced could not compete with that from the Great Lakes. However, when on Nov. 1, 1.929, the Alan Wood Steel Co., of Conshohocken, Pa., leased the Scrub Oak and Washington properties at Mine Hill and Oxford respectively, they made radical changes in the mining and milling processes which greatly reduced the cost of production and pointed the way to a renewed interest in mining in New Jersey. The following factors have been advanced as influencing the reopening of New Jersey mines:

Jan 1, 1938

By K. W. Warren, F. R. Prestridge, B. A. Sinclair

Separating oil from water may seem simple enough, but in fact, tremendous efforts have gone into this common process problem. The petroleum industry is constantly looking for better ways to separate the emulsion of oil and connate water that is pumped from the ground and its latest development, the electrostatic emulsion separator, may find an important offshoot application in hydrometallurgy. The patent-pending OSX coalescer, developed by C-E Natco, recovers entrained solvent from both raffinate and the pregnant strip liquor. It has already undergone successful testing at the Bluebird copper circuit in Arizona and is currently being prepared for testing at a uranium SX plant.

Jan 4, 1978

By M. Safiuddin

Within the mining industry, open-pit mining has progressed to a point where a 200-yard walking dragline is as conceivable today as a 35-yard dragline was just a few years ago. This is possible due to the technological advances and efforts of the excavator manufacturers, and the manufacturers of electrical equipment have always stayed abreast with them in meeting their requirements and in making available their experience with the latest control techniques and hardware from various fields for application in the mining industry. An electrician in the coal mines of Pennsylvania who had not heard the word "thyristor" a few years ago now wonders how the old excavators with Rototrols® and magamps could ever work. The thyristors, transistors and operational amplifiers which were considered too fragile and delicate for a rugged and severe application like the mining industry, today constitute the brain of an excavator control taking commands from the operator and giving signals to the muscles of the excavator to move the bucket within a few seconds. A giant 200-yd bucket filled with overburden moves within seconds of the operator&apos;s command. Digging cycles for these excavators range from 40 to 60 sec depending on the swing angle. With these tremendous production capabilities of the excavators, the equipment failures and downtime become very expensive, and the loss of return on large capital investment for such machines becomes intolerable. Even though these failures and downtimes cannot be avoided completely, a good preventive maintenance program can help reduce them, thus increasing the machine availability. As we shall see below, the causes for breakdowns and failures of electrical equipment can be analyzed and a good preventive maintenance program can be drawn up to eliminate most of these failures.

Jan 9, 1967