Search Documents

By Ernest O. Kartinen

This report is the accumulation of eight years of experience on only one small phase in the business of oil production. It is not intended as a final report but rather as a progress report dealing with the internal corrosion of oil field dehydrating tanks. The corrosion of dehydrating tanks continues to be a problem in the production of crude oil. The deterioration hy corrosion of these tanks falls into three general classifications: (1) Atmospheric corrosion of exterior areas, (2) corrosion of the underside of deck and the rafters and top area of the upper row of staves in that part of the tank which is known as the vapor space, and (3) corrosion of the bottom and shell areas, and the steam coils which are normally immersed in water and thus exposed to the corrosive action of the water. Atmospheric corrosion is primarily a paint problem, and has been omitted in this discussion. The corrosion in the vapor space, in this company's experience, which has been of great concern only in one area. has also been omitted in this discussion. The third, and most troublesome type of corrosion, and the one with which this report deals, is that which occurs in the water-exposed areas of dehydrating tanks, and, to a lesser degree. in some stock tanks. The operating temperature of these waters varies from 80°F to 160°F and the salt counts run from a few thousand to as high as 25.000 parts per million. Corrosion in these tanks occurs in three forms: (1) pits, (2) ringworm type of attack along the vertical and horizontal bolt seams, and (3) as a general attack, spread over a wide area. Steam Coils In dehydrating tanks, our experience has been that the steam coils are the first to show signs of corrosion, and then the shell and bottom areas. This action is not uniform throughout this company's operations. Some installations have coil troubles with very little tank trouble, and some show just the opposite. But in the majority of cases the coils are the more seriously corroded areas. This may be partly due to the fact that we have tried by periodic application to keep a protective coating on the interior areas of the tanks, and some protection has been afforded by these coatings. Through the years several types of hot and cold coatings have been tried with many various methods of cleaning the steel, ranging from use of cleaning solvents to hot and cold Oakite washes, as well as sandblasting. Although experience has shown that a longer life expectancy of a coating is possible after a very thorough steel cleaning job, it has still been necessary to recoat these tanks at least every two or three years. Until a few years ago, vertical spiral steam coil bundles were installed when the tanks were originally erected. When these coils needed replacement, in some cases within 18 months, it was necessary to remove a couple of shell staves to accomplish this task. This required a down time period of several days and was often very inconvenient to the production operations of the leases. This problem was considered on the basis that the coils were expendable, and thus. to eliminate any unnecessary down time when changing coils, the vertical spiral coils were discarded in favor of horizontal flat coils which could be taken in and out of the tanks by way of the cleanout openings, and put together with unions. This made a fairly easily replaceable and repairable coil. But it was still very much of a nuisance when repairs were necessary. Efforts to increase the useful life of the dehydrating tanks led to the adoption of galvanized tanks at an increased initial cost. The zinc coating was depended upon for protection and no other protective coatings were applied. In July, 1944. during the development of a new lease, a 3-ring 1,500 bbl, black iron water tank was converted into a dehydrating tank with steam coils to handle the new production. This tank was coated inside with a cold, brushed-on coating, for protection against corrosion. After approximately 18 months of service, holes developed in the tank and the steam coils. The tank was emptied and cleaned for repairs. The coils were so badly pitted that it was felt advisable to replace them. Coating Becomes Loose Inspection of the tank showed the protective coating to be still in place but loose, and numerous blisters were in evidence. A closer inspection showed that the interior of this tank was so badly pitted under the coating that any further attempt to use the tank was inadvisable. This tank was therefore discarded and a new galvanized tank ordered and set up at considerable expense and inconvenience. In April, 1946, another dehydrating tank installation was made on an adjoining lease. This installation consisted of a 1,500 bbl. 3-ring galvanized tank with two sets of flat steam coils 12 in. and 24 in. up from the bottom. In September, 1947. seventeen months after installation. salt showed up in the boiler feed water. When the dehydrating tank was opened and cleaned, the steam coils were found to be badly pitted — several holes having penetrated through the wall of the pipe. New coils were installed.

Jan 1, 1950

By M. L. Leonardi

THE Searles Lake orebody is located in the north- west corner of San Bernardlno County. It is a dry lake bed with an exposed salt surface covering an area of 12 square miles. Recoverable mineral values are contained in the mother liquor below the surface of the lake. Stratification in the lake bed has separated the brine into two bodies which dlffer in composition. Although liquor is processed from both bodies, this paper will discuss only the upper structure brine. Fig. 1 illustrates a typical cross-section of the two commercial orebodies. The orebody is composed of a porous salt deposit 70 to 90 ft deep. The upper structure is separated from the lower orebody by a 12 to 16-ft thick impervious mud seam, as shown in Fig. 1. These salt structures are composed of 55 pct solid-phase salts and 45 pct voids which are filled with the original mother liquor. The brine wells are drilled to the separating mud seam and cased to wlthin 10 ft of the bottom. This is done to draw the brine horizontally from the bottom of the structure. It is pumped with multistage centrifugal pumps Into the plant at the rate of 3 milllon gal per day. The first process that was successful was developed by Charles P. Grimwood for the recovery of potash. The first evaporator unit was built in 1916. In the early twenties, Dr. Morse worked out a process for the recovery of borax. This made the cycle more efficient, as the end liquor could be sent back to the evaporators rather than being sewered. In 1926 the American Potash & Chemical Corp. was formed as a new company, and the entire plant was remodeled. The plant at that time produced only potash, borax, and boric acid. Since then the American Potash & Chemical Corp. has added processes for the production of USP boric acid, refined potash, sulphate of potash, soda ash, salt cake, lithium concentrates, Pyrobor (Na2B4O7) bromine, phosphoric acid, and lithium carbonate. The main plant cycle may be depicted as a closed cycle, see Fig. 2. The raw material, brine, enters the cycle to be mixed with the end liquor, known as ML2, from the pentahydrate borax crystallizers. The mixture of these two forms evaporator feed. Evaporator feed is pumped to the evaporators where it is concentrated, with respect to potash and borax. In the same operation water vapor, sodium chloride, salt trap salt, and clarifier salt are removed from the cycle, see Fig. 3 for potash plant product. The evaporators produce a concentrated liquor which contains approximately 19.5 pct KCI. This liquor is diluted as it enters the potash plant to keep all salts, except potash (KCI, 97.0 pct) in solution. Here the moist potash leaves the cycle at 100°F. The end liquor, known as ML1, is pumped to the borax pentahydrate crystallizers, where crude borax pentahydrate is crystallized and removed as solid phase. The ML2 is sent back to pan feed to be reconcen-trated, see page 207. Note that the only water to leave the cycle is in the form of vapor and moisture in the solid phase products crystallized. Thus there is a constantly cycling volume of liquor to which brine is added. Since the volume of liquor cycled does not increase, the brine is, in effect, evaporated to dryness. This would be true if there were no liquor losses. But, as in all processes, there are always unavoidable and accidental losses which reduce the volume of cycling liquors. The losses must be made up with brine. The concentration process is the beginning and the end of the cycling liquors. In this process there are three evaporator units of the triple effect counter-current type, that is, there are three pans in each unit and the heat flows in one direction while the liquor flows the other way through the evaporator pans, see Fig. 4. During the evaporation process a great deal of sodium chloride, burkeite, some sodium carbonate monohydrate, and a little lithium-sodium phosphate are crystallized. The volume of these salts is so great that they must be removed as they are formed or the process would come to a standstill. Brine and recycled mother liquor No. 2 enter the third effect evaporator pan from the evaporator feed storage tanks, see Fig. 5. A steady flow of liquor is removed from the bottom of the No. 3 pan and is pumped through the No. 3 cone of the salt trap, a clear liquor being returned to the NO. 3 pan. A portion of this clear liquor is pumped to the second effect pan. This process is repeated in each pan. The liquor from the No. 2 pan is pumped through the No. 2 salt trap cone and returned to the No. 2 pan.

Jan 1, 1955

By L. T. Larson, P. M. Basinski

In the northern Reese River Valley uranium is corroded with Middle Pliocene zeolites. These zeolites were diagenetically derived from rhyolitic volcanic glass deposited in a saline- alkaline lake. X-ray diffraction, scanning electron microscopy, and chemical studies reveal clinoptilolite, analcime, and enonite to be pesent and that these minerals can concentrate at least 0.7% uranium from solution. Most anomalous drill cuttings contain zeolite and zeolites are believed to host the uranium. Research suggests the uranium mineralization is conceptually analogous to the Tono mine, Japan.

Jan 1, 1981

By R. B. Berg

Chlorite veins in the Silver Star district were of little interest to those who were mining gold and silver in the late 19th century. In 1975 unusually pure magnesian chlorite of the variety clinochlore was identified from a "talc" claim in this district. In 1977 tests by Cyprus Industrial Minerals showed that this chlorite was suitable for use in ceramics. Mining begun in that year continues. These replacement veins of chlorite in Precambrian quartzofeldspathic gneiss differ from nearby metalliferous veins to the northwest in both attitude and mineralogy.

Jan 1, 1984

By Howard N. Hall

The compressibility of reservoir rock is a factor which is generally neglected in reservoir engineering calculations. This is due in part to the fact that there is little published information on rock compressibility values for limestones and sandstones. Omission of rock compressibility is undoubtedly justified in calculations for saturated reservoirs; however, in under-saturated reservoirs,* expansion of the rock accompanying decline in the reservoir pressure may be of such magnitude as to affect materially the prediction of reservoir performance. The effect of rock compressibility will be of most importance in: (1) calculation of oil in place by pressure decline data in undersaturated volumetric reservoirs when the limits of the field are unknown or indefinite, and (2) studies of natural water drive performance. To estimate its importance in such cases, a series of laboratory tests were made to obtain usable values for reservoir rock compressibility. The total, or effective, compressibility of any reservoir rock is a result of two separate factors, namely, expansion of the individual rock grains, as the surrounding fluid pressure de-

Jan 1, 1953

By Clemens Jones

The peculiar property of the lode-stone has been known for many centuries. It was very early observed that, by contact with it, iron is magnetized; and it is needless to dwell here upon the history allied to this discovery, now constituting the wonderful science of magnetism. Deposits of magnetic ore are distributed all over the world. The ore is sometimes very rich and comparatively free from gangue, sometimes sparsely disseminated in the native rock. These bodies of lean ore often cover large areas. Modern ingenuity has utilized the principle of the magrtet, originally derived from the ore itself, and really belonging to the time of Plato and Theophrastus, to separate the magnetic ore-particles from the rock which has previously been crushed. This process recovers the ore in the state of a concentrate very rich in iron and, in some cases, desirable for Bessemer purposes. The magnetic separator is no longer a novelty. It was only at the last meeting of the Institute in New York, that Messrs. Birkinbine and Edison (Trans., xvii., 728) and Mr. Robert Cook (Ib., 599) described some of' the principal designs of apparatus in use. E. S. Dana classifies the natural magnetic minerals in the following order: magnetite, pyrrhotite, franklinite, almandite and minerals " containing considerable FeO." Of these, ferroso-ferric oxide, or magnetite, is the type. The proportionate amount of ferrous oxide essential to magnetize the compound, is not established. Ferrous oxide appears to be the only magnetic oxide of iron. Tissandier (Compt. Rend., lxxiv., 531) produced ferrous oxide in the anhydrous state, by the action of carbon dioxide on pure iron at a red heat, according to the equation : Fe + CO2 = FeO + CO. This is black, crystalline and magnetic. Heated to redness in the air, it is converted into Fe3O4. Sidot (Compt. Rend., lxvii., 175) has also produced an oxide exhibiting magnetic polarity, by heating ferric oxide to a temperature

Jan 1, 1891

By E. E. McGinley, L. D. Woodworth

DURING the past several years has occurred what, in the light of future events, may aptly be called the rebirth of the acid Bessemer process. The increased attention given to the technical and metallurgical details involved in the production of Bessemer steels has been exceedingly fruitful, and indicates the value of further research and plant development. In times like these, when the steelmaking capacity of the country is operating at a maximum rate to supply materials for the national defense program, it behooves the Bessemer operator not only to strive to increase production but also to maintain a high standard of quality. The opportunity is ripe, it seems, to recapture fields of application once considered the birthright of Bessemer steels, but supplanted in recent years by open-hearth grades. This involves cooperation all along the line, from the blast-furnace operator to the metallurgical contact man and salesman. The metallurgist's part in this program involves the study of the many steelmaking variables and the measures necessary to ensure constancy in the finished product. It is equally important that the knowledge gained be disseminated widely to ensure the wise application of Bessemer steels in new fields. The merits of Bessemer steels for certain work are well understood. The combined properties of good weldability, machinability and stiffness are unique and fully explain the strong entrenchment of Bessemer steels in certain fields; e.g., skelp for small butt-weld conduit, screw steels machined in automatics, and certain tinplate applications. It is the purpose of this paper to review briefly the physical properties of Bessemer steels as contrasted with those of open-hearth steels, to discuss control measures now employed in the making of Bessemer steel, and to consider the advantages derived from the use of these control measures. PHYSICAL PROPERTIES OF BESSEMER VS. OPEN-HEARTH STEELS A number of Bessemer blows and open-hearth heats were tested for tensile strength, ductility and impact strength. The steels selected were confined to sections from ¾ to 1 ¼ -in. diameter, inclusive, and the carbon content covered was sufficient to yield parallel ranges in ultimate strength for the comparison. Other factors, such as the extent of deoxidation of the steel and variations in chemistry, were kept as comparable as possible. Machined test pieces of 0.505-in. diameter with an 8-in. gauge length were pulled. The data obtained are shown in Fig. 1, ultimate strength being plotted against carbon content. This graph shows that for equivalent carbon content Bessemer steel has on the average 15,000 lb. per sq. in. greater tensile strength and, conversely, for the same tensile strength Bessemer steel requires on the average 0.14 per cent less carbon. The average phosphorus content for the Bessemer steel was 0.090 per cent,

Jan 1, 1941

By H. G. Doll

As a continuation of the earlier paper on the general subject of the SP log, a more complete analysis of certain features of the SP log in shaly sands is given. The pseudo-static SP in front of shaly sands is compared, on a theoretical basis, to the static SP in front of clean sands, as a function of the respective amount of shale and sand in the formation, and of the relative resistivities of the shale, of the uncontaminated part of the sand. and of the invaded zone of the sand. As a conclusion, the advantage of using reasonably conduc. tive mud in this case is shown. The discussion is illustrated by field examples. INTRODUCTION The discussion reported in the present paper is based on a theoretical analysis, and not on experiment. The field examples, joined to the text. are shown only as qualitative illustrations of the essential results of this analysis. Although the hypotheses made in the theoretical developments may perhaps be somewhat improved, it seems, nevertheless, that the results obtained account reasonably well for the actual phenomena, and give a fair approximation of their order of magnitude. The paper contains a mathematical analysis of a tri-dimen-sional distribution of potentials and current lines. due to spontaneous electromotive forces arising at the contact of shales and free electrolytes. as a function of the geometry and of the respective resistivities of the different media involved. It is assumed, although this hypothesis is not proven, that the emf's remain the same even if the shale occurs in very thin layers or in dispersed particles. It has already been pointed out 1,2,3 that, all other conditions being the same, the deflection of the SP log in front of a shaly sand is smaller than opposite a clean sand. When the thickness and the conductivity of a clean sand are large enough. the deflection of the SP log reaches a limiting value which is equal to the "static SP" of the clean sand. It is generally convenient to take the static SP of shale as the reference value or "base line." As a consequence, and for the sake of abbreviation, the expression. "static SP of a clean sand," is often used to designate the difference between the static SP of that sand and that of the shales, which difference is a measure of the total electromotive forces involved in the chain mud sand-shale. A similar limiting value is; also observed for the SP deflec-lion opposite a thick shaly sand, but it is smaller. just as if the total electromotive force involved were smaller in that case. This limiting value has been called the "Pseudo-Static SP" of the shaly sand. The static SP of a clean sand depends on the salinity of its connate water with respect to that of the mud, and, to a certain extent. on the differential pressure which controls the electro-filtration potentials, but it does not depend on the resistivity of the sand. On the contrary. the pseudo-static SP of a shaly sand depends not only on the salinity of its connate water and on the differential pressure, but also on the percentage of shale and on the resistivities of the shale, of the uncontaminated part of the sand, and of the zone invaded by the mud filtrate. If the three resistivities above were equal, the pseudo-static SP would be proportional to the percentage of sand in the shaly sand, and its departure from the static SP of a clean sand having the same connate water would simply be proportional to the percentage of shale. In that case, the pseudo-static SP of a shaly sand containing 10 per cent of shale would he 10 per cent less than the static SP of a clean sand. When. however. the sand is. on the average. substantially more resistive than the shale. the percentage of departure of the pseudo-static SP from the static SP of a clean sand is much larger than the percentage of shale. For that reason, the peaks of the SP log opposite shaly sands are systematically of smaller amplitude when the sands are oil-bearing than when they are water-bearing, all other conditions being the same. This feature is observed even when the sand beds are thick. and even when they do not contain a large percentage of shale. All this has already been described in all earlier publication", but mostly in a qualitative way. The present paper will analyze in more detail the action of the local SP currents which are generated inside of the shaly sands, and which are responsible for the abnormally low value of the pseudo-static SP. The quantitative computations have been extended to the general case of thin interbedded layers of sand and shale, where the resistivities of the shale and sand streaks do not have the same value: they are summarized in charts giving values of the pseudo-static SP of a shaly sand as a function of the different parameters involved. DEFINITIONS The static SP of a clean sand has been defined as the potential that would exist in the mud opposite that sand, were the SP current prevented from flowing. Such an ideal condition is represented on Fig. I-A. By analogy, the pseudo-static SP of a shaly sand can be defined as the potential that would exist in the hole, if the circuit shaly sand — surrounding shales — mud column were interrupted by the insulating plugs placed at the boundaries

Jan 1, 1950

By John F. Abel

"The most conservative persons I ever met are college undergraduates." Woodrow Wilson said that in 1905. No one is saying anything like it today. Chaos on the campus was a cliche of the sixties. Since 1905, education has expanded in every direction. Many more people are being educated for much longer periods of time. The school-leaving age has risen from 14 years to 20 years, on an average. Many are in school until after their 25th birthday. On the surface this situation appears all to the good. Our technical society needs a massive yearly infusion of semitrained (or educated, if you prefer) new blood. The efficiency of our economy and our standard of living are tied to high individual productivity which can be achieved only with an educated work force. Our democratic institutions are said to be founded on an educated electorate.

Jan 1, 1970

By L. L. Anderson, R. E. Wood, W. H. Wiser

Western bituminous coal can be processed to low sulfur liquid fuels by fast reactions. A process (LEFCO) under development at the University of Utah uses coal and catalyst under hydrogen pressure to convert 60 to 70%of the coal matter to fuel liquids and gases. Coals have been processed in small diameter (less than %in.) tubes and at reaction residence times of less than 10 secs. Effects of process variables on the yield and quality of products have been studied. General features of the process and the properties and characteristics of the products produced are presented. Special features of the process that distinguish it from other liquefaction processes under development are also discussed.

Jan 1, 1977

By E. R. Parker, T. H. Hazlett

An understanding of the mechanism of creep of metals requires an accurate knowledge of shape of the time-deformation curve. An expression is developed which accurately expresses the creep curve for a number of structurally stable metals and alloys. VAST strides have been made in the development of high temperature creep resistant alloys; however, no sound understanding of the physical mechanism of creep exists to date. Consequently, creep resistant alloys are still developed by "cut and try" methods formerly so successful but now yielding returns at a continuously diminishing rate. It is apparent to all workers in the field that if the mechanism of creep were understood, much fruitless labor could be avoided. The dirth of fundamental knowledge has not discouraged the theorists. Speculation has flourished and numerous theories of creep have been proposed. A critical review of these theories reveals that, even though there are some general areas of agreement between the majority of the workers, there are many basic questions yet to be resolved.' It is generally conceded that theoretical speculation is far in advance of experimental evidence. The shortage of reliable creep data greatly hinders more rapid progress in this field. It is essential that the effects of different stresses and temperatures on the creep characteristics of metals be quantitatively determined. Once this has been accomplished, it will then be possible to evaluate the effects of alloying additions and, it is hoped, to provide a firm basis of facts for theoretical treatment of the creep phenomenon. The work reported herein was undertaken to determine the effects of such variables as stress, temperature, alloying, and structure on the creep characteristics of some metals. Material and Equipment Nickel was selected as the base material for the current investigation and an experimental program was initiated to determine the effects of temperature and stress on the creep characteristics of this material. Since a large quantity of high purity nickel was required for the proposed program and such material was not commercially available, it was decided to refine, cast, and prepare the required metal in our own laboratory. The resulting nickel test bars had the following composition, given in percentage by weight: Fe, 0.030 (1); Si, 0.003 (2); Ca, 0.001 (1); Mg, 0.020 (2); and S, 0.002 (2); to make total impurities of 0.056. The nickel (balance by difference) is 99.944 pct. The details of the purification process are described elsewhere.' This

Jan 1, 1954

By Paul Soros

The cost of shipping British coal by water to domestic and ex- port users has been expensive. The traditional transportation system functioned as follows: coal in up to 50 different grades was accumulated in railway cars at several loading ports; on the arrival of a vessel, cars were dumped in the desired order to produce the required blend. It was a direct rail- road-to-water interface. Railroad freight was high because of the poor utilization of the large number of small (14, 18 or maximum 28-ton capacity) hopper cars required. Ocean freight was high because the ships were small, mostly on the order of 1500-3000 dwt and even these took a long time to load. Assembling and loading larger cargo presented a challenge in logistics to the ports, the railways and the coal washeries. The accommodation of larger bulk carriers was hampered by a tidal range of up to 24 ft which led to the development of impounded harbors, with locks that limit the size of vessels.

Jan 12, 1973

By L. Webster Wickes

The bad effects of arsenic in commercial copper are well-known to metallurgists. The refining of copper by electrolysis eliminates practically all of the arsenic, provided certain requirements are fulfilled. The first, and most important, of these requirements is, that the voltage of the depositing current shall not be too high. It has been known for some time that the percentage of arsenic in the deposited copper increases with the voltage. To investigate the relation between the electro-motive force (e.m.f.) and the freedom of the precipitated copper from arsenic, the experiments were made, of which a brief summary is here given: I made three copper-arsenic alloys, containing respectively 3.56, 2.24 and 0.96 per cent. of arsenic. From these alloys I cast several anodes. For cathodes I used sheets of thin copper,

Jan 1, 1905

By William P. Blake

In view of the present exposition at Atlanta, and the timely meeting of the Institute in that city, and the expressed desire of the Council for contributions to the knowledge of the mineral resources of the Southern States, I may be permitted to offer some desultory notes upon the subject, chiefly in the form

Jan 1, 1896

By A. L. Mular

Several capital cost estimation procedures are reviewed briefly, although the factored estimate method is discussed in preference. A table of cost versus equipment parameter data is provided, where the cost may be updated from the current value of the M&S cost index for mining and milling. Cost equations are useful to prepare computer programs which perform capital cost calculations. The use of the factored estimate method is illustrated.

Jan 1, 1978

By Wilson B. Emery

The discovery well in the Rock River field, in Carbon County, Wyoming, came in May 1, 1918. The field is on a large anticline having more than 1500 ft. of closure and production is obtained from three sands of the Dakota group. At its peak, production approximated 10,000 bbl. daily and is now averaging 2200 bbl. Total production to Jan. 1, 1930, exceeded 12,500,000 barrels. So far as known to the writer, Rock River was the first light oil field in the Rocky Mountain region to be produced under what we now term unit operation. Though this type of operation was not popularly acclaimed by the oil industry, the Federal Government and the public until many years after the inception of development at Rock River, the officials of the Ohio Oil Co. when acquiring this property were fully cognizant of the economies to be effected by unit ownership and the consequent elimination of competitive drilling and producing of wells, and had this in mind at the time. Thus unit management was introduced in this field at an early date by this company. Area and Management Fig. 1 shows the location of all wells drilled on the Rock River structure and the outline of the productive area as now defined, which amounts to 1380 acres. The hachured line indicates the area now under unit ownership; originally a much larger area was so owned but leases have been canceled as progressive development indicated their lack of oil. The management and operation of the entire productive area is handled by the Ohio Oil Co., which owns the majority working interest. The Continental Oil Co. with a 20 to 35 per cent. interest in much of this acreage, and smaller interests owned by others in some of the leases, constitute the remainder of the ownership. The fee rests in the State of

Jan 1, 1930

By R. P. Abendroth

The hydrogen-water vapor ratio at which Fe-Cr alloy, chromium oxide, andiron chromite coexist in equilibrium was determined between 900" and 1200°C. A thermogravimetric method was used to determine equilibrium conditions. The results fit a straight-line relationship in the temperature region studied, and are given by Reduction experiments were also performed to confirm the results of the equilibrium investigation. ThE oxygen pressures at which Fe-Cr alloy, chromium oxide, and iron chromite coexist in equilibrium have been previously determined by Boericke and angert,' Morozov and Novokharski,' and Katsura and uan. Only one determination (at 1300°C) was made by Katsura and Muan, but it agrees with the results of orozov and Novokharski. The results of Boericke and Bangert, however, differ appreciably from the results of these investigators. Previous studies have assumed that the equilibrium metallic phase is pure iron, but Dahl and Van vlack have shown that the iron contains from about 1 wt pct Cr at 1000°C to over 2 wt pct above 1300°C. The chromium oxide also contains a small amount of iron in solid solution. In the present study, hydrogen-water vapor mixtures were equilibrated with the condensed phases, using a therrnogravimetric method to determine equilibrium conditions. The reaction can be written EXPERIMENTAL General Procedure. The starting material was a sintered pellet of Fe2O3-Cr2O3 solid solution with a hole in the center, and was placed on a fused silica hook. This assembly was raised into the preheated hot zone of the furnace in a helium atmosphere, hooked onto a fused silica hangdown suspended from one arm of an Ainsworth Model RV-AU-1 recording balance, and the starting weight determined. A flowing hydrogen-water vapor atmosphere was then exchanged for the helium by evacuation, and the sample reduced until the weight loss indicated the sample composition to be in the alloy-Cr2O3-chromite field. The tem- perature was adjusted incrementally until constant sample weight was achieved for several hours, to within 0.02 mg. A hydrogen-water vapor atmosphere of different composition was then admitted, and the same procedure carried out. At the end of a series of determinations, the sample was examined by X-ray diffraction to verify the presence of the desired phases. Microscopic examination of the silica hook showed no interaction with the sample, nor did it lose any weight. Several criteria were used to insure equilibrium besides constancy of weight. For a given hydrogen-water vapor composition, equilibrium was approached from both oxidizing and reducing sides by varying the furnace temperature slightly. The resulting slow weight loss or gain was observed for several hours. Constant weight could be re-established by returning to the original furnace temperature. The last criterion used was varying the relative amounts of the phases by further reduction or oxidation, and observing any changes in temperature required for constant weight for a given hydrogen-water vapor atmosphere. None were observed. This procedure was essentially the same as approaching the equilibrium from oxidizing and reducing sides, but larger weight excursions were carried out. Sample Preparation. Reagent-grade Fe2O3 and Cr83 powders were mixed in the desired proportions and heated in air at 1250°C for 2 hr. The mixture was re-ground and heated in air overnight at 1250°C. X-ray diffraction showed complete solid-solution formation as a result of this procedure. The solid solution was then pressed into l/2-in.-diam pellets using Carbowax 4000 as a binder. The hole was drilled in the center, and the pellets were sintered 24 hr at 1250°C in air on a bed of Fe2O3-Cr2O3 of the same composition, contained in an alundum boat. After cooling, the pellet surfaces were abraded with 310 paper to remove any surface compositional differences, such as loss of Cr2O3. Chemical analysis of the sintered pellets was 67.16 wt pct CrP3 and 33.02 wt pct Fe203. Atmosphere Generation and Control. The hydrogen-water vapor atmospheres were generated by passing Matheson ultrahigh-purity hydrogen, with no further purification, through two water bubblers contained in a constant-temperature water bath. Since the water-vapor dew points required in this study were below room temperature, the bath was insulated, and was cooled by thermoelectric-immersion devices. The bath temperature was controlled to 0.0l0C. Since rather high flow rates of about 900 ml per min were used through the furnace tube, an independent check of the dew point was made to insure saturation of the hydrogen by the water vapor. Although the dew point could only be determined to within 1/2"C, the determined dew points agreed with the water-bath temper-

Jan 1, 1967

By T. S. Govindan

The first step in energy conservation in any industrial plant involves implementing many of the day-to-day "housekeeping" items, such as fixing leaks, turning out lights, etc. When this step has been accomplished, additional opportunities require a detailed analysis of the energy systems, evaluation of risks and costs, and assignment of priorities. Examples of conservation schemes drawn from the experience of Du Pont's Energy Management Consulting Services will be discussed. The utility of heat balances for kilns and dryers in minerals processing will be outlined. The input needed from management for the success of conservation efforts will be discussed.

Jan 1, 1981

By A. Kenneth Schellinger

IF the ball mill is considered only from an energy standpoint, it can be thought of as a converter of kinetic energy into heat energy and surface energy. The law of the conservation of energy must apply to the ball mill as it does to any machine or process in nature. The heat energy output of the ball mill is apparent to any casual observer of the operating mill since the outflow pulp will be appreciably warmer than the inflow water and rock. The rock in the ball mill is crushed by shearing of its ionic bonding caused by some impact-induced stresses beyond the elastic limit. As the bonds holding the mineral crystal lattices together are ruptured, new surface area is created on each unit of which a definite number of unsaturated bonds exist. Such unsaturated energy of bonding may be termed the "surface energy," and is a potential energy figure. This created energy was withdrawn from the ball mill system and represents an absorption, or disappearance of heat. To reduce the size of the rock, surface area must be created and with it the at-

Jan 6, 1951

By AIME AIME

BUSINESS forecasting may be an inexact science, if it is a science at all, but in the opinion of the statisticians of the American Telephone & Telegraph Co. it is a valuable aid to the making of future business plans, whether it be used by a telephone system, a manufacturer whose distribution is country-wide or, one whose trade is confined to certain sections. Whatever the defects of business forecasting may be; the American Telephone & Telegraph Co: has employed it since 1921, not only for charting the probable; course of telephone traffic over long-distance lines, but' to determine the needs for new plant and equipment: caused by shifting tides in business or increases in population or general industrial expansion.

Jan 1, 1929