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By Herty, C. H.

No attempt will be made here to review the previous work done by investigators on the general subject of inclusions, because it was discussed sufficiently in an early cooperative bulletin of this series (No. 36, 1928), and reference was then made to general bibliographies. The work described in this present bulletin deals directly with the study of the mechanism of deoxidation of steel with aluminum and the formation of inclusions containing alumina. Unquestion- ably, such inclusions are encountered in most steel-making practices and little has been done to determine their characteristics. Aluminum is used to ensure rapid deoxidation during the solidification stages of the steel. For this reason the possibilities of inclusion elimination are slight and alumina-containing particles will undoubtedly be present in the ingot. Besides this common practice, aluminum is often used in the ladle with other deoxidizing agents such as silicon and manganese. Ladle additions of aluminum are made to rimming steels to obtain the correct partial deoxidation desired in this type of steel. In killed steels the aluminum is added to ensure soundness, as far as blowholes are concerned, in the ingot. In either rimmed or killed steels, alumina or alumina-containing inclusions are found therein, the amount and type depending on the oxidation of the metal, the amount of aluminum added, and the addition of other deoxidizers.

Jan 1, 1957

By E. J. Roberts

Hydrometallurgical operations and many processes in the chemical industry require the separation of dissolved material from solids. One of the decisions which has to be made in designing a plant for such an operation is how this separation shall be accomplished. It is the purpose of this paper to set forth the general principles involved in such separations in order that the optimum flowsheet and equipment may be selected. Countercurrent Decantation with thickeners, or C.C.D. as it is generally known, is, of course, only one way of separating dissolved material from undis-solved. Other unit operations such as Countercurrent Filtration (C.C.F.) and Countercurrent Classification (C.C.C.) are widely used. The same principles may also be applied to centrifugally assisted decantation, as with nozzle or solid bowl type centrifugals, and to separations using screens, either gravity or centrifugal type. Another form of countercurrent washing applicable to granular materials is practiced in continuous ion exchange operations. All of these operations depend on two basic principles, or combinations of these principles. In C.C.D. type operations the solids are concentrated into the smallest possible volume of liquor in each step and the resulting pulp then mixed with a more dilute liquor and recon cen trated, the liquors separated from the more dilute stages being advanced to dilute the more concentrated liquor in a previous solids concentrate, as is shown in Fig. I. This will be termed the solids concentration-solution dilution principle, or, for short, solution dilution. countercurrent decantation- type circuits. The second principle used in washing solubles from solids is that of solids concentration-solution displacement. Here the solids are restrained from movement while wash solution is forced through the interstices in a counter-current fashion, as in Fig. 2. In the simplest application of this principle, once the "cake" has been formed, it is not disturbed until the operation is completed. In continuous filters, the cake is merely moved under the successive washes and the displaced filtrates removed as in Fig. 4. Often, however, after one or two displacement washes, a repulping step is introduced, the cake reformed and washed again. This procedure brings the solution dilution principle into play as well as the solution displacement principle. Merely thickening ahead of filtration, which is often operationally advantageous, does not hybridize he circuit. It still can be a pure solution displacement operation from the washing

Jan 1, 1961

By H. E. McKinstry

Movement on a fracture of irregular shape can cause local widening of the fissure and thereby offer freer channelways for circulation of ore-depositing solutions. This influence: coupled with large areas of wall rock available for reacting with ore solutions in brecciated and shattered ground can account for locally active deposition of metals and the resulting ore shoots. Such irregularities in the fracture system may be caused by local variations in the strength of rocks and by pre-existing lines of weakness, especially if these stand at favorable angles to certain components of the fracturing stress. Therefore correct interpretation of the mechanics of fracturing should permit deductions as to structurally favorable places on unexplored portions of the vein system. Introduction It has long been recognized that movement on a curved or irregular fault surface is capable of separating the walls in certain portions of the fault, but until very recent years the importance of this mechanism as a factor in localizing ore shoots has escaped proper recognition. A short time ago W. H. Newhouse' presented a careful analytical study of displacements and their corresponding open spaces. For reasons that will be discussed later, it frequently happens that portions of the vein which are favorably oriented are not merely wider but also richer than the average. In many cases the widening with its accompanying richness coincides with very minor changes in the dip or strike of the vein, irregularities that commonly escape notice unless the vein is mapped in detail and a careful geometrical analysis made. While the relationship between the width of the vein and the changes in dip or strike has been recognized as a matter of observation, the irregularities have been accepted as more or less the result of accident. There has been very little effort except in isolated cases to find out the causes of these changes in dip or strike. Yet it is clear that if the causes can be recognized and expressed in terms of geologic structure the geologist will know where to look for repetitions of these favorable conditions either on extensions of the same vein or on adjoining veins. Any lack of understanding of the causes is due to the limitations of our ability to interpret our observations and not to the sheer capriciousness of

Jan 1, 1941

By H. E. McKinstry

Movement on a fracture of irregular shape can cause local widening of the fissure and thereby offer freer channelways for circulation of ore-depositing solutions. This influence: coupled with large areas of wall rock available for reacting with ore solutions in brecciated and shattered ground can account for locally active deposition of metals and the resulting ore shoots. Such irregularities in the fracture system may be caused by local variations in the strength of rocks and by pre-existing lines of weakness, especially if these stand at favorable angles to certain components of the fracturing stress. Therefore correct interpretation of the mechanics of fracturing should permit deductions as to structurally favorable places on unexplored portions of the vein system. Introduction It has long been recognized that movement on a curved or irregular fault surface is capable of separating the walls in certain portions of the fault, but until very recent years the importance of this mechanism as a factor in localizing ore shoots has escaped proper recognition. A short time ago W. H. Newhouse' presented a careful analytical study of displacements and their corresponding open spaces. For reasons that will be discussed later, it frequently happens that portions of the vein which are favorably oriented are not merely wider but also richer than the average. In many cases the widening with its accompanying richness coincides with very minor changes in the dip or strike of the vein, irregularities that commonly escape notice unless the vein is mapped in detail and a careful geometrical analysis made. While the relationship between the width of the vein and the changes in dip or strike has been recognized as a matter of observation, the irregularities have been accepted as more or less the result of accident. There has been very little effort except in isolated cases to find out the causes of these changes in dip or strike. Yet it is clear that if the causes can be recognized and expressed in terms of geologic structure the geologist will know where to look for repetitions of these favorable conditions either on extensions of the same vein or on adjoining veins. Any lack of understanding of the causes is due to the limitations of our ability to interpret our observations and not to the sheer capriciousness of

Jan 1, 1941

By M. E. Learmont, R. J. Lipp, I. Iwasaki

In the selective flocculation of iron ores, the concentration of alkaline earth ions in pulp solutions plays a critical role. Sodium silicate, alone or with sodium tripolyphosphate, has been used as a dispersant. When Ca+ + concentration exceeds 15 to 20 ppm, however, only a strong complexing agent, such as ethylenediaminetetraacetate (EDTA) was found to be effective (Heerema, Lipp, and Iwasaki, 1979). Some iron ores release Ca+ + in excess of 20 ppm. With ores that contain gypsum, the Ca+ + concentration may reach several hundred ppm. The purpose of this investigation was to compare the effectiveness of EDTA with nitrilotriacetate (NTA) in countering the adverse effects of Ca+ +, particularly at high Ca+ + concentrations. Emphasis was placed on the use of NTA since it is more cost-effective than EDTA. It is also used in detergents in some countries (Malaiyandi, Williams, and O'Grady, 1979). NTA, like EDTA, forms a soluble complex with Ca+ + with a 1:1 molar ratio. Its structure and the value of log Kca are given below together with EDTA (Shibata, 1963). [ ] For experimental materials, an equal weight mixture of Lac Jeannine hematite and a high-purity quartzite from Thompson, MN, both ground to - 30 µm (- 560 mesh) was used. Selective flocculation test conditions and procedures were identical to those used in previous investigations (Heerema, Lipp, and Iwasaki, 1979). The optimum level of starch addition for the above mixture was determined to be at 300 g/t (0.6 lb per st). Initially, a series of selective flocculation tests were performed on the mixture pulped with 10-3M CaC12 (40 ppm Ca + +) at pH 11. With no NTA present, flocculation of the entire suspension resulted. The selectivities achieved in tests with 90, 100, and 150% of the stoichiometric amount of NTA were virtually identical to each other and also to the selectivity of separation obtained in the absence of Ca+ + Such an observation could have been expected since Ca+ + concentrations up to a few ppm may be tolerated in selective flocculation (Krishnan and Iwasaki, 1982). A similar series of tests were performed at 10-2M CaC12 (400 ppm Ca+ +). The results are shown in Fig. 1 as grade¬recovery curves. For comparison, the results obtained in the absence of Ca++ are included. At 90% of the stoichiometric amount of NTA, a large enough concentration of uncomplexed Ca+ + was left in solution to cause indiscriminate flocculation. Note in this figure that NTA is capable of countering the adverse effect of Ca+ + even at this high concentration when it is used in excess of stoichiometric amounts. The free Ca+ + concentrations at 100 and 150% are calculated to be 2.5 and 0 ppm, respectively. [ ] The relative effectiveness of NTA and EDTA was then compared at 100% of the stoichiometric amount using 10-2M and 10-3M CaCI2 (Fig. 2). EDTA appears to be slightly more effective than NTA. The free Ca++ of 0.02 ppm in 10-2M CaC12 with EDTA compared to 2.5 ppm free Ca+ + with NTA might account for the difference. As evident, prohibitively high additions of EDTA and NTA were required to complex high concentrations of calcium ion. The use of both of these agents would result in the accumulation of complexed Ca+ + in recycle water.

Jan 1, 1985

By P. K. Foster, A. McNabb

A consideration of the literature shows the inadequacy of Fick's Laws to describe the diffusion of hydrogen in steels below 400°C. These laws are modified an the assumption that hydrogen is delayed at fixed sites in the lattice. Approximate and exact solutions of the resulting nonlinear system are derived for simple geometrical shapes. The results qualitatively account for the observed anomalous behavior. Experimental methods for verifying the theory are suggested. 1 HIS paper presents a new analysis of the diffusion behavior of hydrogen in steel based on a physical model which supposes that hydrogen atoms wander in a random manner through the crystal lattice, but tend to get trapped or delayed at certain fixed sites uniformly distributed throughout the metal. These sites, which will be called traps, are regarded merely as potential wells of significantly greater depth than those encountered in regular regions of the crystal lattices and no assumptions are made concerning their nature or origin. The results of experimental studies of the diffusion of hydrogen in iron and steel have usually been reported in the literature in terms of a diffusion constant D derived under the assumptions that the hydrogen concentration C is governed by Fick's laws.1 Fig. I is a composite of published graphs of the man. ner in which the values of D, so derived, vary with temperature. It is convenient to consider this material in two categories; the high temperature results above 400°C, and the results at lower temperatures. The graphs 2, 3, 4, 5 in the first class lie within a factor of three of each other and are relatively consistent compared with the low-temperature values. There is an increasing divergence in values of D with decreasing temperature till at room temperature they are spread over three orders of magnitude. Small values of D have been obtained for work-hardened specimens.' It is evident that D is a function of other variables besides temperature in this range and that these neglected variables are in some way connected with the work hardening experienced by the specimen. In view of evidence for an interaction between hydrogen in solution and dislocations9'10 and adsorption on crack surfaces,' some doubts must be entertained about the validity of Fick's laws and their associated physical model of noninteracting particles in random motion through the medium. More direct evidence of their inapplicability to the diffusion of hydrogen in steel was first produced by Darken and smith." Consider the permeation of hydrogen through a plate of thickness a under a boundary concentration Co at the ingoing, and zero at the outgoing, face. If Fick's first law1 is valid, the steady state flux P, through unit area is DCo/a. In addition, the concentration C varies linearly throughout and Qo, the mean quantity of hydrogen in the medium, is co/2. Compare Qo with Q1 the mean quantity required to saturate the same specimen to a uniform concentration G. In this case Ql = Co and hence the ratio

Jan 1, 1963

By L. F. Pett

ALTHOUGH Kennecott's orebody has long been outlined, it is still necessary to define further its limits. This mine, long an advocate of churn drill methods, recently supplemented its practice by using a diamond drill. So far, the diamond drill holes have been along the main canyon floor which traverses the mine area. This zone, highly fractured, is cut by numerous friable quartz veinlets encountered within the porphyry. These veinlets, formed by filling contracted porphyry fractures with hot, siliceous, mineral-bearing solutions, are often more highly mineralized than adjacent porphyry. They pulverize on contact, yielding only slight amounts of core. For this reason neither analysis of core recovered (amounting to 37.5 pct of approximately 10,000 ft of hole drilled) nor sludge analysis considered separately would give correct assays. The following equation has been adopted: actual weight theoretical actual weight core — theoretical weight sludge Drilling is done un.der contract. Collection of core and sludge samples together with double-checked assaying is done by the company. Microscopic, specto-graphic, and X-ray examination of rock specimen saved is carried on at the University of Utah. A fund, set up by Kennecott Copper Corp. at the University, has encouraged cooperation in solution of mining research problems. The drill used is a Longyear hydraulic powered by a Waukesha 26-hp gasoline motor. A pump, Bean Royal type, is powered by a 7-hp Briggs-Stratton gasoline motor. Weight of unit is 4000 lb and is placed under tripod of 35-ft wood poles within a 25-ft sq area. The following results have been attained: Avg depth of hole drilled, ft 1215 Avg drilling depth per 8-hr shift, ft 10.11 Core Size, In. Avg depth of NC casing, ft 21 2 11/16 Avg depth of NX casing and size core, ft 178 2Ye Avg depth of BX casing and size core. ft 427 1% Avg depth of AX casing and size core, ft 585 1 5/32 Through the use of metal sludge collection boxes, 12 ft long, 18 in. wide, and varying from 12 to 24 in. in depth, sludge recovery has been maintained above 95 pct. Samples, both core and sludge, are assembled for each sample interval and averaged in 50-ft bench increments. Determinations for mineral values are made at both the mine and mill. Assay results varying in excess of 0.05 of copper assay values are rerun to determine correct assay. The organization chart for the Kennecott Utah copper mine is shown in Fig. 1. The Utah mine requires approximately four men per shovel shift to drill solid rock, properly slope banks, and trim loose material from the top of bench sections in making them safe for men and equipment working below. During recent years, while the mine has been worked day and night, powder crews have worked day shift only. Series of toe holes drilled back of advancing electric shovels comprise approximately 70 pct of all mine drilling. These holes, spaced about 21 ft apart, have a depth of 24 ft. Of the footage drilled, 25 pct is for vertical holes either 24 or 28 ft deep, spaced about 28 ft centers along the top rim of banks. This combination of toe holes, using an Ingersol-Rand DA 35 drifter mounted on a tripod and the vertical holes using an Ingersol-Rand Type X71 wagon drill is standard practice above the pit elevation. These benches are 68 ft high, with a few exceptions, while benches below the pit elevation are 50 ft high and require very little drilling other than toe holes. Five benches, varying in height from 80 to 100 ft, require a combination of toe holes plus vertical holes and bank holes or electric churn drill holes. Bank holes using the DA 35 drifter and electric churn drill using Bucyrus-Erie Model 29T, account for 5 pct of feet drilled. Until the past year, drilling of fill material on upper levels was accomplished by churn drill method. Wagon drills are now used for fills because they can be set up and drill a hole an hour. It is necessary to run an air drill 7 hr for each 8-hr shovel shift. Average drilling rates during the past year were as follows: DA 35 drifter using 2 and 3-man crews — 4.36 ft per man hr X 71 wagon drill using 2-man crews — 6.45 ft per man hr DA 35 drifter bank holes, 3-man crews — 2.53 ft per man hr Bucyrus-Erie churn drill, 2-man crews —1.9 ft per man hr Total mine avg — 4.57 ft per man hr Mine practice assigns powdermen to job locations where they perform all drilling and blasting work within the area. Almost as much labor is consumed in springing and loading holes as in drilling them. Average powder consumption is approximately as follows: Per Electric Shovel Shift, Lb To spring and chamber holes — 50 Blasting — 500 Trim banks — 50 One fifth of all powder used is Hercules hercomite bag powder while four fifths is Hercules gelamite 65 pct strength in 1 Vi in. x 8 in. sticks. Frozen material, overhanging from top banks, creates a winter hazard to shovel operators and equipment. Experiments are being conducted with a high-speed Hercules powder in an effort to eliminate this condition. Banks are trimmed by powdermen who lodge 8 or 10 bundles of powder, containing 15 or 20 sticks each, across the upper surfaces of each working face. To each bundle of powder is attached a primer with 6-ft fuse which is lighted as the powdermen, who have lowered themselves down the bank on ropes, ascend to safety. Three angle dozers, D8 caterpillars, make grades and move supplies for the average 31 drilling machines working daily. Compressed air is furnished by three Ingersol-Rand compressors, each with rated capacity of 3750 cu ft of air per min at 100 lb reservoir pressure.

Jan 1, 1952

Edward A. UehliNg, New York City (communication to the Secretary*):—In adding my mite to the discussion, I wish to touch on a few points which bear emphasizing and perhaps a little further elucidation. Mr. Grammer says that he "found the electric pig-breaker at Duquesne, if used in connection with the iron-chill, less expensive and more satisfactory " thau the casting-machine. The cost of handling the iron over the Duquesne casting-niachine is about double the average cost of the other Uehling machines at the several Carnegie plants. It is nearly as expensive to run as the Hey1 & Patterson machines, and while Mr. Grammer's statement is, no doubt, true, as applied to that particular machine and breaker, it should be borne in mind that the machine at Duquesne had embodied in it several new features, which were not improvements; also that it was taxed beyond its economic capacity. The machine at the Lucy furnaces under the management of Mr. Scott handled the output of the two furnaces, and saved

Jan 1, 1905

By P. K. Foster, C. M. Payne, A. McNabb

Some measurements of the rate of loss of hydrogen from cylinders of iron and steel are analyzed in terrns of a trapping theory. The apeement is encozcraging and gives rise to estimates for the density of traps in the metal. Furthermore, the results appear to be consistent with the assumption that the diffusion constant D for the steady flux of hydrogen through iron lies on the extrapolation of the linear curve (log D us 1/T) obtained at higher temperatures. IT has been shown in a previous paper1 that the literature relating to hydrogen diffusion in steels contains sufficient evidence to invalidate the application of Fick's laws to hydrogen diffusion in steel at low temperatures. To account for the deviations from simple diffusion behavior a trapping theory was developed, and the fundamental laws modified accordingly. In the present paper, new data on the evolution of hydrogen from long cylinders are presented, and together with some published data are examined in terms of the requirements of the theory.' Properties of solutions of the basic equations derived previously1 and appropriate to the present experimental conditions are outlined in the first section as they determine the form in which the experimental data must be presented for a comparison of theory and experiment. Two new solutions not previously reported have been derived as described in the Appendix. The experiments and treatment of data are then given in Sections 2 and 3 and the results are discussed in Section 4. 1) THEORETICAL CONSIDERATIONS The hydrogen-diffusion theory1 applied in this paper postulated that lattice-dissolved hydrogen at a concentration C diffuses randomly in accordance with Fick's first law, but that the lattice contains a uniform density N of traps which can capture and delay hydrogen atoms. kC atoms are trapped per second in a region containing unit concentration of vacant traps while p are released per second in a region containing unit concentration of occupied traps. On this basis it was shown (Eq. [30] of Ref. 1) that, when local changes in the lattice-dissolved concentration C are slow enough for equilibrium to be established with the traps, the system is represented in dimensionless form by the equation:

Jan 1, 1965

By AIME AIME

THE Coal Division holds its fall meeting in the Pocahontas coal field, at the West Virginian Hotel, Bluefield, W. Va., Oct. 9 and 10. The first day will be a busy one-two sessions for the presentation of papers and a dinner in the evening. Hon. E. Fudge, Assistant Undersecretary, Mines Department, and R. V. Wheeler, head of the Mines Research Board of Great Britain, will be the guests of the Division. Mr. Wheeler will discuss the British Mining Act as relates to the coal industry. George S. Rice, Chief Mining Engineer, U. S. Bureau of Mines, will present an account of the recent meeting at Buxton in England, of representatives of England, Germany, France, Belgium and the United States to formulate a plan and to correlate research work now in progress in the various countries. The second day the members will be the guests of the operators on a trip through the Pocahontas field. The work of preparation for the meeting is being actively pushed by committees headed by T. H. Clagett, R. M. Lambie and H. D. Smith, and a good attendance, both local and from the general membership of the Division, is anticipated. Because many will make the trip by car the principal automobile as well as rail-road connections to Bluefield are given here. The program for Friday, Oct. 9, follows:

Jan 1, 1931

By F. E. Jaumot, A. Sawatzky

IT as long been recognized that there is a need for accurate systematic data on diffusion in solids. Originally, such data were needed to check existing theories but, more recently, it would appear that it could be used most advantageously as a guide to, or a check for, much needed extensions of the theory of diffusion. The awareness of the conditions which are important to experimental accuracy, the availability of the materials for accurate experiments, and the techniques have improved to the extent that it would now seem to an experimentalist that, unless extensions of the theory are made which take into account the fundamental parameters of the atoms, the electrons, and the lattice in some detail, the field of diffusion will rapidly become an empirical or semi-empirical field. The present series of experiments was designed to provide accurate data on the diffusion of the elements of the IB and IIB subgroups in silver; that is, to provide data on the diffusion in silver of three face-centered-cubic elements with roughly similar chemical properties, but with different atomic or ionic sizes and, similarly, for three noncubic elements. The elements of these two subgroups have different valences, so that the data will not give any significant information on differences due to the crystal structure of the solute. The present paper reports data on the diffusion of copper and mercury in single crystals of silver; the data for the other elements of the IB and IIB subgroups were reported previously by the authors1'2 and by Tomizuka and Slifkin.8 Experiment The general technique used was identical to that previously described1,2 and will not be repeated here. In all cases, the sectioning technique and high specific activity isotopes" were used. The short half-life of Cu64 made decay corrections more important than for the other isotopes, and necessitated around the clock shifts while data were being taken. Each section was counted at least twice (as was true for all longer half-life isotopes) and a monitor was counted along with each sample. Data for the diffusion of mercury in silver are presented at a greater number of temperatures than for the other solutes. This is a result of two circumstances. First, six (of 30) samples had to be discarded because of pitting or recrystallization which occurred during the diffusion runs, even though the samples had sustained high temperature prediffusion anneals. Either of these was a very rare phenomenon in the other experiments, and their occurrence in this case is considered in more detail below. Second, the curves of the logarithm of the activity of the sections vs the square of the penetration deptht were, in general, quite good, but frequently seemed to show one point to have high activity and the next point to have slightly low activity in terms of the best straight line. When this occurred, there was remarkable regularity of the high-low sequence. In any event, the results, as far as diffusion coefficients are concerned, were not affected by this amalgam effect. In fact, the mercury data had the highest internal consistency of any of the data. Results Diffusion of Copper in Silver—-Diffusion runs were made at eight temperatures In the temperature range from 700° to 950°C, for times ranging from 5 to 45 hr. A linear curve of the logarithm or the activity vs the square of the penetration depth was obtained for all samples. Table I summarizes the results for individual samples and Fig. 1 gives a plot 02 the logarithm of the diffusion coefficients as

Jan 1, 1958

By F. W. Lake

The ultimate production from a natural reservoir of petroleum is inversely proportional to the gas-oil ratios existing during the producing life of the reservoir whenever gas is the major expulsive force in the recovery. In other words, in the period during which gas is the major expulsive force the ultimate production will be increased if the gas-oil ratio is decreased, and vice versa. This condition prevails in the greater number of the present producing districts. While this relation is difficult to prove from actual operation, on account of the present paucity of detailed observations, it must be admitted after a study of the forces and conditions governing the recovery of petroleum from natural reservoirs. Where gas and oil exist under pressure in sand interstices and water movement is not freely possible, the force expended in moving the oil to the well is the expansion and movement of the gas through the pressure differential existing between the interior of the reservoir and the well. If pressure and solution conditions in the untapped reservoir are such that the relation between gas and oil volumes at atmospheric conditions is as 100:1; and if during the producing period, until the gas is exhausted, the relation between the gas and oil volumes produced is 300:1, it follows that only one-third of the oil has been produced and the remaining two-thirds cannot be recovered unless some extraneous force is introduced into the reservoir. This serves to illustrate the importance of gas-oil ratio control during normal producing operations. Gas-oil Ratio Control Eliminating natural conditions in a reservoir, which govern gas-oil ratios, such as the physical properties of the oil and gas, the physical characteristics of the reservoir strata and the original pressure and solution conditions in the reservoir, which cannot be controlled by operation practice; and also eliminating operating conditions that apply to the reservoir as a whole, such as well spacing, well locations, relative completion dates, various penetrations and drilling practice; there remains but one condition in each well that influences the gas-oil ratio and that is

Jan 1, 1928

By James Ruddy

THE medical program of the Climax Molybdenum Co. is under the supervision of the department of industrial medicine of the University of Colorado, of which James J. Waring, professor of medicine at the University Medical School, is director. Dr. Waring is consultant and direct supervisor of both the hospital and industrial medical department at Climax. At Climax the program is in charge of the medical director and the associate physician, Dr. Galen M. Hover. The hospital at Climax is completely equipped with all that is necessary for the practice of scientific medicine and surgery. Only graduate registered nurses with experience in industrial medicine are employed. Being only a few hundred yards from the portal of the mine. acci-

Jan 1, 1946

By A. J. Lyon

THE stability and permanence of any structural material used in aircraft are of paramount importance. The spontaneous hardening, or age-hardening; which takes place in some of the aluminum alloys under ordinary conditions of temperature and atmosphere, is accompanied by an increase in tensile strength and proportional limit and a decrease in elongation or ductility. Within the last few years the introduction of a number of strong and ductile casting alloys led to a study by the Materiel Division, Air Corps, of the permanence of the physical properties in several of these alloys. It has been found that even though some alloys have good properties directly after casting or heat treatment, they are not satisfactory for stressed parts that require a combination of strength and ductility. It has also led to the conclusion that all alloys that can be hardened by artificial aging-heating in a temperature range below 170° C. (340° F.)-will harden spontaneously if allowed to stand for a sufficient length of time. It follows that, in aircraft work where the factors of safety are limited on account of the necessity of keeping the weight of the structures as low as possible consistent with their safe operation, the properties of the alloys in the stable or final condition should be used as a basis for design rather than the properties obtained on the material directly after casting. The work of Wilm in Germany, Hanson and Gayler at the National Physical Laboratory in England, and Merica, Jeffries, and others in the United States, has shown that the spontaneous hardening is characteristic to a greater or less extent in all aluminum-base alloys in which the solubility in the solid state of the alloying constituents decreases with the temperature. It has been shown that, by heating to a temperature as near as possible to the melting point of the material and soaking at that temperature for a sufficient length of time and then quenching or cooling rapidly, a maximum amount of the soluble constituents can be retained in solution and the condition of maximum hardening effect upon aging can be obtained. Also, in ordinary sand and chill castings, without heat treatment, a sufficient amount of the alloying constituents is held in solution to cause important changes in the final physical properties.

Jan 1, 1928

H. H. Stoek, Scranton, Pa. (communication to the Secretary): Mr. Rothwell's condemnation of my paper on the International Correspondence Schools as not giving an impartial view of the whole field of such enterprises, because it was confined to the description of a single one, might be legitimate if I had undertaken or professed to do anything else than that which I was requested by the Secretary of the Institute to do—namely, to give an account of this particular institution. This is a sufficient answer to all his direct or implied criticisms upon my omission to mention either persons or organizations outside of the special limits set for me. Recognizing fully that personalities have no place whatever in the Transactions, I regret the necessity of making the following statement in answer to Mr. Rothwell's charge that I omitted to give due credit to Mr. Ewald, a former principal of the International Correspondence Schools. The Colliery Engineer School of Mines was started in 1891, and its first student was enrolled October 16, 1891. During the fall of the same year the mine-mechanical course was laid out along the same general line that had already been followed in the mining course. This mine-mechanical course was the foundation from which sprung the later developments of the several mechanical courses. The latest circulars of information of the International Correspondence Schools give the following as their distinctive features: (1) courses of instruction for particular occupations,

Jan 1, 1900

By H. D. Outmans

In steady vertical flow, the interface of an immiscible liquid-liquid displacement is horizontal for any flow rate below the critical. In nonvertical flow, however, the shape of the interface in the steady state does depend on the flow rate, and the purpose of this paper is to calculate the unsteady interfaces during the transition of one steady state of flow to another. A knowledge of these transient interfaces is of considerable importance in reservoir engineering where the calculation of breakthrough recovery depends on the instant the interface reaches the producing wells and on the shape of the interface at that time. Although the emphasis is put on transient interlaces, which eventually approach stable equilibrium, it is shown that if the displacement exceeds a critical rate no equilibrium is possible. The interface is then unstable and viscous fingers are formed during the displacement. The critical rate and the shape of the transient and equilibrium interfaces are affected by the effective interfacial tension; but since this effective interfacial tension appears in the calculations only in combination with the inverse square of the thickness of the medium, its effect in the reservoir would appear to be negligible compared to its significance in model experiments. INTRODUCTION Stability criteria and the early growth of interfacial disturbances in a plane parallel to the boundaries of a dipping formation in which oil is displaced by an incompressible fluid were described in a previous paper.l This type of instability is significant in thin reservoirs. However, if the reservoir has appreciable thickness, then interfacial stability in vertical planes, normal to the upper and lower boundaries, also becomes important (the displacement is supposed to be parallel to these vertical planes). The difference between the two stability problems is that, in the first case, the intersections of the interface with planes parallel to the boundaries are normal to the direction of the displacement; in the second case, the intersections, this time with vertical planes, are not normal to the displacement. Instead, they are tilted at an angle which depends on the displacement rate. The tilt of steady interfaces was calculated by Dietz2 who also determined the critical rate of displacement for stability in the vertical plane by assuming that this rate would coincide with an interfacial tilt equal to the dip of the formation. The critical rate thus calculated is the same as has been found for thin reservoirs (see Eq. 1.1 of Ref. 1 and of the present paper). Dietz's calculation of the stable tilt was verified by laboratory experiments and the agreement was found to be fairly good.3 It is doubtful, however, that stable tilts actually exist in the reservoir because a change in production rate is not followed by an instantaneous adjustment of the interface to the new rate but, rather, by a transition period during which the interface changes from one equilibrium tilt to the other. The principal objective of this paper has been to describe these transient interfaces without putting any restrictions on the flow conditions or the shape of the interface, as had been done previously. The second objective was to compute the critical velocity, taking into account capillary effects, and the third was to evaluate, at least qualitatively, the shape of the front at rates above the critical, again without making the simplifying assumptions introduced by previous investigators.2,3 In the following sections two examples are given of the calculation of interfacial motion. The first describes this motion for an initially horizontal interface in a dipping layer, and the second for a vertical interface in a horizontal layer. The mathematical formulation of the problem is nonlinear in the boundary conditions, and this prohibits its solution in closed form. Instead, the solution is obtained in the form of higher-order approximations. 1 Before proceeding to a description of the mathematical model, however, we define two quantities

C. Edward Stafford, Chester, Pa.:—Doring all my business life, I have been engaged in the manufacture of Bessemer and open-hearth steels, but, during my long connection with the Shoenberger Steel Co. of Pittsburg, I had some experience in the manufacture of high-grade puddled iron for horseshoes, and in making, by Dr. Otto Wuth's process, extremely pure, low-phosphorus puddled blooms (analyzing from 0.005 to 0.01 per cent. of phosphorus and sulphur), which were melted with low-phosphorus pig-iron in acid open-hearth furnaces, to make extra locomotive fire-box steel. I have also seen the Danks puddlers in operation at different times and places, notably where they were most successful, at the Otis Steel Works, Cleveland, Ohio; then under the management of our friend, Mr. S. T. Wellman. These Danks blooms were made solely for open-hearth melting-stock, to which they were well adapted. (The unavoidable presence of bits of ore-fix imbedded in the mass of the metal always prevents the profitable manufacture of merchant iron from Danks' blooms.) With the experience just described, I was to some degree in position to value fairly the means, methods and results of Mr. Roe's mechanical puddling from the metallurgical or technical and economic points of view, when given an opportunity by Mr. Roe to see his puddling-furnace or machine in operation in Pottstown, Pa. Briefly, the furnace, with water-cooled bottom, is rectangular in plan, about 20 by 8 ft. in the clear, suspended by trunnions at the middle of the long sides, at a height of 17 or 18 ft. above the general level. The oscillation (65" each way from the vertical) is accomplished by geared segments (attached to the downward-projecting side or trunnion-plates) with which engage pinions driven by a reversing engine. The whole section

Jan 1, 1906

By John J. Stokes

Literature on the electrolysis of aluminum from cryolite melts and on the structure of these .melts is surveyed critically. Data on density, freezing point, and other properties are reviewed. Theories of the electrolysis are examined in the light of these data. Two theories are presented which account equally well for the observations. In the early days, the process was thought of as a simple one. The actual mechanisms must be tremendously more complex. This paper is devoted to a rather narrow part of the whole subject, namely, what ions are present in the bath, and by what mechanism the current is carried. Using cryoscopic data, Rolin has determined the following composition for molten cryolite. Na2,AlF 3Na + 3F + AlF [1] He postulates the following equation for the ioniza-tion of alumina at low concentrations Al2O3 Al + AlO2 +O. [2] At concentrations above 0.025M he supposes the ionization of alumina to proceed as follows Al2O3 AlO + AlO2. [3] Rolin's mechanism of electrolysis for the more concentrated solution in Eq. 3 is as follows. The AlO' ion migrates to the cathode. where it is dis- charged, giving metallic aluminum and 0' ions which migrate to the anode. The AlO2- ion migrates to the anode, where it is discharged, giving Al ions and oxygen which reacts with carbon to form CO2 In the case of the extremely dilute solution in Eq. 2 the Al ion migrates to the cathode and the AlO2-and 0 migrate to the anode as before. Another possible mechanism for the electrolysis follows. Ionization of Cryolite Na3AlF4 = 2Na + 2F + NaAlF, Na + AlF-AlF+Na + F [4] Addition of Alumina 2Na2AlF+ 2AL2O4 6Na + 3A12O3F4 [5a] Al2O2F 2AlOF2 [5b] Cathode Process AlF, + 3e+ 4F + Al. [6] Anode Process AlOF2 + 2F AlF1 + 1/20, + 2e or A12O2F + 4F-2A1F; + 0, + 4e. [7] Although both Rolin's and the present mechanism of the Hall process may be qualitatively satisfactory, present data are not adequate for quantitative tests of the theories.

Jan 1, 1959

By G. R. Frank, R. E. Willett, E. H. Hollingsworth

The most generally accepted equilibrium diagram for A1-Fe alloys has a eutectic system on the aluminum side with an essentially insoluble constituent of the formula, FeAl,, as the second phase. In 1938, Bradley and Taylor1 did report a phase change of FeAl,, but this change has never been confirmed. According to them, FeA1, is the stable phase only at higher temperatures; at lower temperatures, it is converted into Fe2Al7 and aluminum. It has now been found that there is, in fact, a phase change of the Al-Fe constituent on the aluminum side of the equilibrium diagram. This change, however, is not the one reported by Bradley and Taylor. The alloys used were cast by continuous processes and had these analyses: Fe - 1.98 to 2.02 pct, Cu-0.01 pct, Si - 0.01 pct, Mn - 0.01 pct, Mg - 0.00 pct, Zn - 0.00 to 0.01 pct, Cr - 0.00 pet, Ti - 0.00 to 0.04 pct. The constituent in these alloys was identified by X-ray analysis with a Guinier camera and by chemical and X-ray powder diffraction analyses. Two procedures were used to separate constituent for the last two analyses. In one procedure, it was separated by treating a sample with a solution of methanol saturated with iodine. And in the other procedure, it was separated by first applying, at 12 amp per sq ft in 15 pct sulfuric acid at 70°F, an oxide coating to a sample, and then dissolving this coating in a solution of 35 ml of 85 pct H3PO4 and 20 g of CrO3 per liter. Several observations directed attention to a phase change of the A1-Fe constituent. Differences that appeared too great to be accounted for by micro-structure alone were found in the voltages required to apply the same thickness of an oxide coating to products from rapidly and slowly chilled ingot. Even more striking was the difference in appearance of the coatings themselves. One applied to a product from a rapidly chilled ingot was dark gray in appearance, in fact, almost black, while one applied to a product from a slowly chilled ingot was essentially white. Also, even a short period of thermal treatment at an elevated temperature of products from rapidly chilled ingot led to the same anodizing behavior as that of products from slowly chilled in-

Jan 1, 1962

By G. R. Kotler, W. A. Tiller, W. C. Johnston

Experiments carried out on 100 g samples of molten tin and Sn-Pb alloys showed that the magnitude of the field strength, H, does not effect the supercooling, aTn, at which the initial nucleus of solid forms. However, the nuwlber of nuclei forming per cc, n, is found to increase greatly with H for fixed ATN and to increase with ATN for fixed H. The value of n increases greatly with the presence of solute and is found to he indefiendent of the cooling rate of the simples. Further, the most effective time for stirring to enhance n is immediately following the initiation of recalescence. The effect of inducing nucleation with the aid of a mechanical impact both in the presence and absence of stirring has also been studied. All proposed mechanisms for the enhancement of n by physical means seem to be inadequate in accounting for these results. IN any real nucleation experiment there are two effects influencing the results that would not be predieted from classical homogeneous nucleation theory. These may be separated into chemical and mechanical effects. The chemical effects are twofold. 1) Nucleation catalysts are present which enhance the nucleation frequency of new grains over that predicted by classical homogeneous nucleation theory.' 2) Solute will restrain the growth of nuclei so that many others may form.2,3 The mechanical effects are also two-fold. 1) Vibration (sonic or ultrasonic) of the freezing liquid enhances the nucleation frequency of new grains over that given by the chemical effects alone.4-6 2) Macroscopic fluid-flow effects produce the same effect as l).'7' It is also possible to influence the nucleation experiment by certain physical effects such as the application of electric and magnetic fields.9 From classical homogeneous nucleation theory one would predict the following relationship between the nucleation rate, N1 (number of nuclei formed per unit volume per unit time), and bath supercooling, AT, for an isothermal experiment.

Jan 1, 1963