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By Hugh R. Van Wagenen, Allen H. Rogers

There are few natural monopolies comparable with the nitrate industry. Perhaps the only other one is, curiously enough, also an essentia1 fertilizer material, viz., potash, of which the Germans have heretofore held practically a monopoly due to the existence in their territory of the most important known deposits of potash salts. And although nitrates in minute amounts are found in many desert regions, the only deposits capable of being worked commercially exist in Chile. Combined nitrogen in the oxidized form is an essential for plant life. Nature provides it mainly through the agency of nitrogen-fixing bacteria. But where lands are cropped artificially this supply is too small, and gradually the nitrogen supply becomes exhausted. In order to continue farming, it is necessary to furnish a supply of nitrogenous plant food, and this is done by putting on various substances containing combined nitrogen. These consist of various animal wastes, ammonium sulphate, the ammonia of which is obtained in the destructive distillation of coal, and Chile saltpeter. The latter is immediately available as a plant food, the nitrogen being in the required form. The other substances must oxidize before they are available. Resides its use as a fertilizer, Chile saltpeter is the source from which the bulk of the nitric acid of commerce is derived. The use of nitric acid in the manufacture of almost all modern explosives is, of course, well known. Importance of the Nitrate Industry Chilean nitrate, the existence of which was first mentioned in 1809, is said to have been first exported in 1830. Only a few thousand tons per annum were exported for some years, but the amount gradually increased until, in 1879, when the Chile-Peruvian war began, the export amounted to about 300,000 tons. This nitrate was largely produced from the Province of Tarapaca, until then, Peruvian territory. By the terms of peace with Peru in 1884, this province, as well as Tacna, became Chilean. The Bolivian Province of Antofagasta was also acquired as a result of this war, and thus Chile, with the deposits in her own territory, acquired control of the whole supply of nitrate. At the present time, exports are approximately 3,000,000 metric tons per annum,. having a

Jan 1, 1918

By Irwin R. Higgins

CONTENTS A. Introduction B. System Description C. Uranium Pilot Plant Programs D. Summary INTRODUCTION The Chem-Seps Continuous Countercurrent Ion Exchange (CCIX) contactor was first conceived of in 1951 at the Oak Ridge National Laboratory. In the 27 years that have passed, there has been a steady stream of pilot plant process development studies on a variety of processes far too numerous to mention. These have been in the area of water and waste treatment, chemical processing, ore leach treatment, and many others. Many successful production systems have been installed and operated in a variety of applications. A few of these are described herein together with a description of the system and its operational characteristics. SYSTEM DESCRIPTION Chem-Seps Continuous Countercurrent Ion Exchange* is a single loop in which various sections are separated by valves to isolate the sections performing different functions simultaneously. (Refer to Figure 1). To explain the working of a typical unit, let us use a simple configuration used in water softening or demineralization. The resin is moved in small increments by the hydraulic ram action. All solution flows are countercurrent to the flow of resin. The contaminants are removed in the process cycle and the resin is moved in the pulse cycle. A controller in the effluent stream from the treatment section senses the proper limit permissible in the effluent. In the process cycle, the influent enters through a set of distributors, moves downward and leaves through a set of collectors. Simultaneously the regenerant enters through valve RE and leaves through valve WA. The rinse enters through valve RI and its duration is controlled by an interface controller. In the process cycle, valves B, C, and D are closed, isolating all the sections. The duration of the process cycle is 4-10 minutes depending on the contaminants to be removed and is controlled either by a timer if the contaminants are fixed, or a controller in the effluent stream, if the contaminants fluctuate at short intervals. Valve A is open and resin is dropped to the pulse section simultaneously with the removal of contaminants in the treatment section, regeneration of loaded resin in the strip section, and rinsing of regenerated resin in the rinse section. As the resin drops through the valve A, it is backwashed to remove the suspended solids or resin fines. Removal of these fine particles is important to avoid the unnecessary pressure drop in the bed and plugging of the distributors. At the end of process cycle, all flows going into the unit and out of unit are automatically shut off. The valve A closes and valves B, C, and D open in proper sequence. A slug of water enters through valve PU, a predetermined incremental volume of resin moves into the regeneration section, an equal volume of regenerated and rinsed resin enters the bottom of the treatment section, and an equal volume of the loaded resin leaves the top of the treatment section and goes into the resin reservoir section. (The resin movement is plug flow with the Reynold's number being in the laminar region of the curve, and no fluidization occurs during the pulse cycle.) The total time required for proper sequencing of valves and the movement of resin is 20-30 seconds. At the end of this period, the valves B, C, and D close and valve A opens. The solution valves open and normal steady state operation begins. All valves are interlocked and properly sequenced. The resin movement is precisely controlled by sonic devices. Special Features of Chem-Seps CIIX "Downflow"*: The raw feed in the treatment section moves downward and the resin moves upward in the treatment section. The "downflow" of feed overcomes the handicap encountered in "upflow" systems. The "upflow" of feed requires a certain minimum flux during process cycle to lift the bed and keep it

Jan 1, 1979

No. 230. Two engineers, technical graduates, three to five years, experience. One to take charge of 'pyrite mining in Canada; the other to assist in the mining work at the head office in New York. Salary for the right man, $5000. No. 231. Two young engineers, preferably men who have just graduated from college who are looking for an opportunity to work up with a reputable mining company. Men who have had some practical experience will be considered. No. 232. Assayer. Wet analyses, principally of lead, zinc, sulphur and insoluble. Assayer will also have some mill sampling and experimental work in a new flotation installation, as well -as control of regular mill operation and development-work samples front the mine. $75 to $100 per month and board, according to experience of candidate. No. 233. Engineer to lay out, erect and operate calcium carbide and ferrosilicon plant in the State of Washington. One furnace, 1500 hp. No. 234. Professor of metallurgy for school of mines in western state. $3000 per year to man properly qualified for the work.

Jan 9, 1917

By C. H. Samans, G. F. Tisinai, J. K. Stanley

The addition of nitrogen (0.10 to 0.20 pct) to Fe-Cr-Ni alloys of simulated commercial purity results in a real displacement of the u phase boundaries to higher chromium contents. The effect is small for the (Y + s)? boundary, but is pronounced for the (y + a +s)/(y + a) boundary. Although there is an indication of an exceptionally large shift of the n boundaries to higher chromium contents, especially in steels with nitrogen over 0.2 pct, the major portion of this apparent shift results from the fact that carbide and nitride precipitation cause "chromium impoverishment" of the matrices. The effect of combined additions of nitrogen and silicon to the Fe-Cr-Ni phase diagram is demonstrated also. Nitrogen can nullify the effect of about 1 pct Si in shifting the (y + o)/? phase boundary to lower values of chromium at all nickel levels from 8 to 20 pct. NItrogen can nullify this U-forming effect of about 2 pct Si at the 8 pct Ni level, but not at the 20 pct Ni level. The alloys studied were in both the cast and the wrought conditions. There are indications that the u phase forms more slowly in the cast alloys than in the wrought alloys if both are in the completely austenitic state. The presence of 6 ferrite in the cast alloys accelerates the formation of U. Cold working increases the rate of o formation in both cast and wrought alloys. THE major improvement in Fe-Cr-Ni austenitic alloys in recent years has been in the addition or removal of minor alloying elements to facilitate better control of corrosion resistance, sensitization, and heat resistance. One shortcoming of the austenitic Fe-Cr-Ni alloys, which never has been completely circumvented, is their propensity toward u formation. In the AISI-type 310 (25 pct Cr-20 pct Ni) and type 309 (25 pct Cr-12 pct Ni) steels, sufficient amounts of u phase can form, if service or treatment is in a suitable temperature range, to cause severe embrittlement. Also, there is a growing conviction that this phase may be contributory to some unexpected decreases in the corrosion resistance of certain of the 18 pct Cr-8 pct Ni-type steels. The present paper discusses the effect of nitrogen additions on the location of the (r+u)/d and the (y+a+u)/(y+a) phase boundaries in the ternary Fe-Cr-Ni system, for cast and wrought alloys of simulated commercial purity, and in similar alloys containing up to about 2.5 pct Si. The objective is to define compositional limits for alloys which will not be susceptible to u formation when used near 1200°F (650°C). An excellent review of the early studies of the u phase in the Fe-Cr-Ni system has been compiled by Foley.1 Rees, Burns, and Cook2 have determined a high purity phase diagram for the ternary system, whereas Nicholson, Samans, and Shortsleeve3 are- stricted themselves to a portion of the simulated commercial-purity phase diagram. Both groups of investigators show almost an identical position for the commercially significant (y+u)/y phase boundary. Further comparison of the work of the two groups indicates that, below the 8 pct Ni level, the commercial alloys have a decidedly greater propensity toward u formation than the high purity alloys. The two groups of workers agreed that both the AISI-type 310 (25 pct Cr-20 pct Ni) and the type 309 (25 pct Cr-12 pct Ni) steels are well within the (y+~) region and that the 18 pct Cr-8 pct Ni-type alloys straddle the U-forming phase boundaries. Nicholson et al.3 showed, in addition, that these boundaries shift toward lower chromium contents if greater than nominal amounts of silicon or molybdenum are added. The effect of nitrogen on the location of the s phase boundaries in the Fe-Cr-Ni system has not been known with any certainty. In 1942, an approach to this problem was made by Krainer and Leoville-Nowak,' but at that time they apparently were unaware of the slow rate of s formation in strain-free samples and aged their samples for insufficient times, e.g., 100 hr at 650°C (1200°F) and 800°C (1470°F). For this reason, it would be expected that their (y+ u) /y boundary would be shifted toward lower chromium contents (restricted ?-field) when equilibrium conditions were approximated more closely. Procedure for Studying the Alloys The alloys used were prepared in the following way: Heats of 200 lb each were melted in an induction furnace. A 5 lb portion of each heat was poured into a ladle containing an aluminum slug for de-

Jan 1, 1955

By P. W. George

The rapid increase in cost of discovering new orebodies by churn drilling in the Tri-State district has led to some attempts to lessen the expense by using geophysical methods. Electrical prospecting was tried three or four years ago, but no successful results were recorded. In 1926, the Federal Mining and Smelting Co. engaged the North American Exploration Co., of Houston, Texas, to make some tests with the torsion balance. At first, it was thought that the most favorable conditions for discovery of ore deposits with the torsion balance would be in locations where the ore was known to occur at rather shallow depths, therefore the first trial was made at Ducnweg, east of Joplin, where some zinc ore had been developed at a depth of 130 ft. The gravity gradients at 61 stations on a tract of about seventeen acres indicated plainly one large zone of maximum gravity and a smaller narrow zone of minimum gravity. Fourteen churn-drill holes, half of which struck ore, show that all the ore found was located outside the zones of maximum and minimum gravity. In the zone of maximum gravity the limestone beds were closest to the surface, and the first chert beds encountered were at the greatest depth. The results (shown in Table 1) indicated that the gravity of the limestone was greater than the gravity of the fractured chert together with its orebodies, and probably also greater than the bouldery soil and clay on top of the limestone. A cross-section of the Duenweg lease is shown in Fig. 1.

Jan 1, 1929

By Frederic A. Delano

The subject of the wear of rails seems to have attracted an unusual amount of interest in the last six months, and in the bope of doing my share to direct opinions in what seems to me the right direction, I will attempt to discuss briefly the several ways in which the shape of the rail-section may affect the life of rails. In a paper presented at the Boston meeting of the Institute (Trans., xvi., 594),

Jan 1, 1889

By C. H. Chou, A. Sauveur

The senior author of this paper has expressed the belief that when gamma iron transforms into alpha iron on reaching the A3 point, each gamma grain does not change bodily into one or more alpha grains but that the alpha phase forms first at the boundaries and along the crystallo-graphic planes of the austenite grains.1 To quote: On cooling through the point As, at about 900° C, iron passes from the gamma condition to a new allotropic form generally designated as alpha. This transformation, however, is not instantaneous. There are good reasons for believing that it begins at the grain boundaries and along the octahedral planes of the crystals and that it progresses until each grain of gamma iron is changed into a grain of alpha iron, the resulting structure being similar to that of gamma iron. Were it possible to retain

Jan 1, 1929

By T. E. Weirich

Although 1931 witnessed no new discoveries of oil or gas in Oklahoma, the year is especially outstanding because of price demoralization, political intervention, abandonment of marginal properties, a strict curbing of oil flow from wells in flush fields and an extension of proration into settled fields. In spite of a strict, adherence to proration agreements, the price per barrel of oil sank from 65c to $1.07 to a low level of 10c to 22c. Table 1 gives the price range for crude oil in Oklahoma during the year. Under a martial law order by the governor, a period intervened from Aug. 4 to Oct. 10, of complete shutting in of the flush fields. This condition created an abrupt decline in the production curve during the two months' period. Oklahoma, as elsewhere, is passing through a "transition period" of relieving expensive above-ground storage by maintaining the more copious supplies of crude oil in the natural reservoirs. For many years the thousands of small, nearly depleted wells have been considered as being the "backbone of the industry." A large number of wells of this type are now idle or completely abandoned. More than 1100 abandonments were recorded by the state Corporation Commission during the year. The industry is becoming less interested in these small wells, replacing the former attitude by the curbed potentialities of flush pools. Many of the major companies are grouping these marginal properties with those of adjacent owners, operating the whole

Jan 1, 1932

By Rixford A. Beals

It has been observed with considerable accuracy that if the major U. S. mines were moved to Mexico tomorrow, many of them would be losing money. But the companies would continue to operate, losses or not, because they would have to. And some of the newest and most promising low grade ore projects in the U. S. would never have "gotten off the ground" had they faced the equivalent of the mining taxes now in effect in Mexico. No one of the various mining taxes in Mexico seems prohibitive by itself. Taken together, on the balance sheet, however, the picture changes. Production and export taxes alone take from 20 to 40 pct of the gross product value for base and precious metals.

Jan 2, 1955

By C. E. Reistle

All crude oils become more viscous when chilled, but the only oils that congeal and precipitate paraffin to such an extent as actually to cause production troubles are those that contain an appreciable amount of wax. In handling these oils of high wax content, three distinct problems may be encountered before the oil reaches the refinery. The first problem is the precipitation and accumulation of paraffin in the well, either in the oil string or on the face and in the pores of the sand. The second problem is the accumulation of paraffin and the congealing of oil in the transportation lines. The third problem is the precipitation of paraffin and the formation of tank bottoms. Factors That Control the Solubility of Paraffin in Crude Oil Two main factors, possibly three, govern the solubility of wax in crude oil. The first of these is temperature. The solubility of wax in crude oil increases with an increase in temperature, and as the temperature approaches the melting point, the wax becomes soluble in all proportions in the crude oil. The higher the melting point of a wax, the less soluble it is in crude oil below its melting point. All crude oils containing wax can be chilled to a point where the oil is saturated with wax. If the temperature is decreased below this point, some of the wax will crystallize from solution. Fig. 1 shows the effect of temperature on the solubility of crude paraffin in oil. The second factor is the amount of volatile constituents and gas removed from the crude oil. Evaporation of the volatile constituents and gas lessens the volume of the oil and concentrates the solution of wax in the oil; therefore less wax can be held in solution at a definite temperature. As the natural amount of wax present in the oil is constant, this results in the oil becoming saturated with wax at a higher temperature than if the volatile constituents and gas were still in the oil. As an example of this, a fresh sample of crude oil having a gravity of 39.8

Jan 1, 1928

By Lyall Zickrick

Numerous brands of virgin pig lead are used in the manufacture of lead and lead-alloy cable sheath for commercial cables. In changing from one brand of pig lead to another a readjustment of press operating conditions is nearly always necessary. This is due largely to different flow characteristics, and some brands extrude at a much lower pressure than others; for example, copper-bearing lead requires much more pressure than a low-bismuth lead under the same operating conditions. With the modern type of lead press the extrusion practice in general differs very little. Molten lead at a temperature of 375" to 400" C. (710" to 750" F.) is cast in a water-cooled cylinder and allowed to cool or solidify into a slug for six to nine minutes, This slug is forced into the die block and around the core tube through which the cable runs. The • die block is held at an optimum temperature by means of gas flames, usually 175" to 225" C. (350" to 435" F.). Measurements of the temperature of the cable sheath taken at the time of extrusion have covered a range of 190" to 225" C. (375" to 435" F.). According to Tammann, the rate of extrusion for a metal under constant pressure through a simple orifice is almost doubled for each 10" C. rise in temperature. Because of the irregularity of die-block construction, such a great increase is not obtained in lead-cable extrusion practice. To obtain more definite information about the effect of small percentages of metals usually present as impurities in virgin pig lead, a series of compression tests were made covering several different brands of lead and various alloys. Since the usual temperature of the sheath is approximately 200" C. as it emerges from the die block, these compression tests were all performed at 200" C. Five different brands of virgin pig lead were selected, as follows: Brand A: A desilverized western lead of very high purity. This lead contains neit,her copper nor bismuth. Brand B: A bismuth-free southeastern Missouri lead, usually containing 0.05 to 0.08 per cent copper. Brand C: A copper-free mid-western desilverized lead of very good grade, usually containing around 0.06 to 0.10 per cent bismuth.

Jan 1, 1932

NOTHING makes the run-of-the-hall Congressman feel quite so secure as to be on an investigating committee. It's sure fire publicity for one thing and is a convenient excuse for absence from Congressional sessions when controversial issues are being balloted. The minerals procurement program has just had a thorough investigation by Congressmen of the House Interior and Insular Affairs Committee who heard valuable testimony from men like John D. Morgan, director of materials procurement, DPA. He listed over 40 government agencies concerned with mineral affairs. Testimony disclosed the justification for many of the agencies but Congressmen and mine operators have been regarding the defense minerals program in the same light as did the mining student who remarked to the descriptive geometry prof "it's not the intrinsic difficulty of the problem which gives me trouble; it's the multiplicity of detail."

Jan 9, 1951

Florida State Geological Survey, Tallahassee, Fla Herman Gunter, State Geologist A list of publications will be sent upon request Citizens of the state may obtain publications available without cost, others may have them for postage, or they can be sent express collect Twenty Annual Reports have been issued from 1908 up to and including the 21st-22nd Annual Report (1931). Only three are now available; 4th Annual Report (1912), 15th (1924) and 18th (1927) Reports since 1921 contain statistics on mineral production. All reports contain papers on various subjects, many of which are still available separately, and are so indicated in the list of publications. Seven bulletins have also been issued, principally of interest to paleontologists Bulletin 7, The Pensacola terrace and associated beaches and bars in Florida (1931), is of more general interest Bulletins will be sent upon receipt of postage. Thirteen Press Bulletins, most of which are available, have also been issued, but are of minor interest

Jan 1, 1933

AVERY great profit is derived from removing the gilding and retrieving gold, without destroying the works of silver or other metal. If this method did not exist, the greater part of the gold that is put on certain works would be lost. Even though you might think to scrape it off patiently with a sharp scraper, if it had been drawn with draw-plates, or if it were at the bottom of objects where the scraper could not enter easily, it would be utterly in vain. Therefore, I find that to do this it is necessary to use one of three methods. The first is when it is found on a thin object. Take a large crucible, fill it with mercury, and heat it on a little furnace. When you see that it begins to boil and simmer, put your work in it and stir it around, shaking and rubbing it well in this, and finally rub it with a scratching tool until you see that the mercury has drunk up and absorbed all the gold. Then, having done this, take the said mercury and pass it through an untanned leather purse, and in the bottom of this you will find all the gold like sand. Put this in the bottom of a crucible or in something else over a charcoal fire and evaporate it. If the objects are of a thicker form the gilding is removed from them in another way, by covering them with powdered sulphur and lighting a fire on them. When you see them burning well with the fire all around, beat them in a clean bowl of wood or something else and collect everything that separates with the sulphur from the work; this will be gold in the form of a leaf wherever it has been touched by the fire. The gold is then extracted from this burned sulphur by purifying it in a cupeling hearth with lead. The third method is to touch the gold that you wish to take off the works with an aqua fortis made from saltpeter, rock alum, vitriol, sal ammoniac, and some verdigris.* This acid dissolves and eats the gold by virtue of its corrosive power. Having thus touched the gold with this acid and having saturated the latter with a quantity of gold, put it in a cucurbit and evaporate it over a little furnace as is done with silver, collecting the acid and the spirits if you wish.

Jan 1, 1942

By B. M. Larsen, L. S. Darken

SOME years ago we collated all laboratory data then available to us on the distribution at equilibrium of manganese and of sulphur between metal and simple slags, and used the results in setting up an equation, which proved to be in accord with determinations of the distribution ratio of manganese and of sulphur between liquid steel and open-hearth slag, over a wide range of operating conditions. We now present an outline of our calculations and inferences on these two closely related questions, which are of especial importance because of the advisability of conserving manganese wherever possible. In general, our results show that in the open-hearth furnace equilibrium between metal and slag, with respect to both manganese and sulphur, is substantially attained during the finishing period of the heat, or in about a half hour to an hour after any additions were made. This implies that the end result will be identical whether manganese is added as alloy or metal to the liquid steel or as oxide to the slag. The proportion of total manganese retained by the steel is favored: (I) by use of the minimum amount of lime, consistent with other operating limitations, required to give a lime-silica ratio of about 2.4, which usually corresponds to a minimum practical slag volume; (2) by a high concentration in the slag of MnO relative to FeO; (3) by high operating temperature. Absorption of sulphur by the slag from the liquid metal is favored: (I) by large slag volume; (2 by a high concentration of active (or "free") lime and of manganese oxide dis) solved in the slag; (3) by low concentration of silica, iron oxide, and phosphate dissolved in the slag. DISTRIBUTION OF MANGANESE BETWEEN SLAG AND METAL AT EQUILIBRIUM On the basis that the distribution of manganese between liquid steel and slag is controlled by the reaction [FeO + Mn = MnO + Fe [A]slag metal slag metal] the distribution at equilibrium, at a given temperature, is expressed by the equilibrium constant for this reaction, which is defined as [K" aMoO aFeI1 dFec) aMn] where a is the activity of the molecular species denoted by the subscript. The activity of each of the several components, although it is not known precisely, is approximately equal to the concentration of each component expressed as its mol fraction; that is, as the ratio of the number of mols of the given component to the total number of mols of all the molecular species present in the metal or slag, as the case may be. Moreover, since the activity, or concentration, of iron in the liquid metal is in fact substantially constant, the term [afe] may be combined with K" to give a new constant K'. Making these changes,

Jan 1, 1942

By R. E. Wade

The Butte, Anaconda & Pacific electrification is of peculiar interest, in an incidental way, to the entire mining fraternity, and especially the engineering branch, not only in this great Northwest country but throughout the entire Western mining country, which is rich in minerals and water power. It is probably fair to say that the prime object of mining and smelting engineering is to reduce the cost of production, and in the case in hand the relative location of mines and smelter brings the cost of transportation of ore to the front. While some might assign this item to the railway people, it is inseparably a part and parcel of the general scheme of the production of metal from the ore. In considering the electrification of the B., A. & P. railway the mining and smelting engineer, above all, wants to know what saving will be effected by the change in motive power. Unfortunately the new power has been in use during a very limited period and on the Smelter Hill section of the road only, and no reliable data, from actual service conditions, can be obtained until the entire electrified section has been in service for a reasonable length of time. Any remarks on this subject at the present time, therefore, must of necessity be general in nature and more or less descriptive. The railway, electrical and mining worlds and the country in general are indebted to the B., A. & P. railway for the pioneer work it is now doing, as it undoubtedly marks the beginning of the electrification, within the comparatively near future, of all transcontinental roads between the Missouri river and the Pacific coast. Together with this goes the development of an untold wealth in water power and all natural resources within the same territory. For the first time in the history of electric railway work, in this country, direct current at a potential of 2,400 volts is being used. With this potential there is a great saving in transmission of energy to the locomotives and there are only two substations, one at either end and 26 miles apart, for supplying the power for the movement of trains of heavy tonnage over the main line and for switching movements at terminal and intermediate yards, and comparatively little feeder copper is required.

Jan 1, 1914

By G. Rinelli, A. M. Marabini

A wide-ranging series of experiments has been carried out on value minerals (sphalerite, smithsonite and hematite) and gangue minerals (quartz and calcite) to assess the properties of various commercially available vegetable and synthetic tannins as dispersants for these minerals in a finely ground state (<5 microns). Experiments to determine the dispersing power of each reagents on every mineral have been performed through sedimentation tests run first in water and afterwards in the presence of a collector having specific action on the mineral concerned. The tests have been extended to a wide range of dispersant concentrations, maintaining the pH and collector concentrations at the levels known to be the best for the flotation of the various minerals. By comparing the results obtained on each mineral, conclusions have been drawn on the possibility of using different classes of vegetable and synthetic tannins in the selective flotation of fine particles. These results have been related to the structure of the tanning compounds and to the surface properties of the minerals.

Jan 1, 1980

By Roland W. Rammler

With oil consumption increasing more rapidly than known reserves in industrial countries, there has been a growing interest in the production of synthetic crude oil. The main starting materials for such production are coal, oil shale and tar sand, all of which occur in enormous quantities in North America. A process sequence suitable for all three of these starting materials incorporates a preliminary retorting step to produce oils for subsequent hydrotreating. For this retorting step, a technique known as the Lurgi-Ruhrgas process has proven highly efficient. The process has been commercially used for the flash carbonization of coal and has also been tested in pilot- plant experiments with oil shale and tar sand.

Jan 1, 1970

Jan 1, 1953

By S. Shapiro, J. A. Ford

The crystallo graphy of several grains of the lamellar Ni-Ni3 B eutectic solidified under conditions appvoachirt equilibriun has been examined.. A preferred interlace relationship has been observed in this system which may be described as: A detailed study of this interface by means of an atomistic model reveals the interface Plane to be puckered and more accurately describable as: Analysis of the atomic configuration on these planes reveals that this interface conforms to the orientation criteria proposed for directionally solidified lanzellar eutectics. In addition, a model is proposed to help explain the growth of a "puckered" interface. DURING the past several years an increasing number of unidirectional solidification experiments on eutectic alloys have been reported in the literature. The primary emphasis, in most cases, has been the effect of growth variables on microstructure. Some authors have, however, studied the crystallographic orientations and interfacial relationships resulting from these experiments. Four crystallographic studies have been published;&apos;-4 in each of these there is a factor which tends to prohibit the extension of the observations beyond the particular system. In the Al-CuA12 system, the approximately equal volume fractions of the phases have resulted in sorrie controversy as to which phase constitutes the matrix. In the Mg-Mg,Sn eutectic the presence of several interconnecting lamellar systems2 complicates the analysis. The two remaining eutectics. 1nSb-b and Al-Ali, are both rodlike (the latter exhibits a plate morphology at low solidification rates): the matrix in each of these alloys is the simpler (fcc) phase. Studies of nucleation in eutectic alloys indicate that the more complex constituent is the nucleating -.phase.&apos; For the purpose of an analysis of interface crystallography it was deemed desirable to study a lamellar system in which the matrix was the more complex and, presumably. the nucleating phase. Recently it has been shown that there is a eutectic in the Ni-B system between Ni3B and i; preliminary investigation by the authors indicated that the matrix in this eutectic is the boride phase. The structure of Ni,B is reported to be orthorhombic, the compound being isostructural with cementite. This eutectic is therefore analogous to that between austenite and cementite. Furthermore, the Ni-B system is not susceptible to a competing eutectic reaction as occurs in the Fe-C alloys; nor does it exhibit a eutectoid decomposition. For these reasons the study of the interfacial relationship in the Ni-Ni3B eutectic was undertaken. PROCEDURE Ingots of nominal composition 3.5 and 3.6 wt pct B were induction-melted in boron nitride crucibles within a graphite susceptor under a boric oxide slag; a dynamic argon atmosphere was maintained over the melt to prevent rapid oxidation of the susceptor. The raw materials used were 99.97 pct Ni from Huntington Metals Division of International Nickel Co. and 99.8+ pct B chips supplied by the United Mineral and Chemical Co. The analyses of the starting materials are listed in Table I. The melt was held at 1500cC for 2 hr to insure complete reaction and allowed to cool to room temperature. The castings were chemically analyzed for boron and were metallographically examined for uniformity. The metallographic samples were mechanically polished through 0.1 p A1,0, and etched with Carapella&apos;s reagent. Each master casting was cut up to make several specimen blanks which were remelted, in boron nitride crucibles, to form ingots of 1/2 to 3/4 in. in diarn by 7 in. long. These ingots were unidirectionally solidified using a modified vertical Bridgman technique. The rate of solidification was assumed to be equal to the uniform rate at which the crucible-susceptor assembly was withdrawn from the induction coil. This rate was varied from 1.18 to 2.21 cm per hr. In order to perform these experiments it was found necessary to redetermine the eutectic composition. This was accomplished by the zone-melting technique described by Yue and lark.&apos; An ingot of 4.5 wt pct B was zone-melted in a horizontal boron nitride boat 7-1/2 in. long with a 112-in.-square cross section. A

Jan 1, 1967