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By Thomas E. Howard

Recipient of the 1975 D. C. Jackling Award - "For his vision and initiative in defining, planning, directing, and accomplishing mining research programs; for his leadership in focusing worldwide attention on the need for research to improve underground excavation for mining and civil applications; and for his lecture. . ."

Jan 1, 1976

By J. Philip Neal, Carroll P. Rogers

Feldspars, the most abundant minerals of the igneous rocks, occur in numerous forms and mixtures. The feldspars of commercial significance are found in widely distributed pegmatites as large crystals usually free of iron- bearing impurities and thus suitable for hand-cobbing, and also in larger bodies where the ore contains various types of feldspar inter- mingled with quartz and relatively free of iron- bearing impurities, or at least readily unlocked from impurities present at relatively coarse mesh. The latter type of ore includes some pegmatites, and the ''alaskite" bodies so common in the Spruce Pine district of North Carolina. On the west coast of the U.S. and in Oklahoma there is-r has been--commercial recovery of natural feldspathic sand as a source of alumina in glass and ceramics. "Aplite" in commercial terminology is a light-colored igneous rock with a granitic composition and a fine sugary texture, often banded with readily removable iron impurities. Two areas in Virginia produce aplite for the glass industry: one located in the vicinity of Piney River, Amherst County, and the other near Montpelier in Hanover County. According to Deer et al. (1966) the word feldspar derives from the Swedish feldt or falt (field) and "spath:" chunks of rock appearing in tilled ground overlying granite. Castle and Gillson (1960) indicate a Germanic origin, citing "spat," which is said to refer to any transparent or translucent material which is readily cleavable. The term "spar" has in the past been applied to minerals other than feld- spar, such as barite, calcite, and fluorite. It is correct to call the latter "fluorspar." There is a true barium feldspar, but it is rare and of no present economic importance. What is recognized as feldspar or "spar" by present producers and consumers consists of three silicate minerals which, if pure, would have the formu- las KAISi,O, (microcline or orthoclase), NaAlSi,O, (albite), and CaAl,Si,O, (anorthite). These are almost never found in pure form in nature, but occur together in great abundance in a three-component system. A considerable number of different combined ratios of these three exists, with the exception that isomorphism between potassium spar and calcium spar is very limited. User specifications for feldspar products are largely built around the prevalent naturally occurring ratios. Pas- sages following will refer to "K-spar," "Na- spar," or "Ca-spar." Nomenclature and Descriptive Terms Relating to both the mineralogy and the economics of feldspar are certain terms whose coverage it is useful to specify. Commercially, aplite is a feldspathic rock mined and beneficiated in two locations in Virginia, in which both titanium and feldspar minerals are present-the latter now being the major, if not the only, economic product. Technically, the term aplite when applied to this rock is of questionable accuracy. But, in light of accepted commercial usage, the term will be here used to designate it. Regarding the Virginia rock, Ross (1941) is cited.

Jan 1, 1975

By Roscoe E. Bell

BETWEEN 1945 and 1948 the author made studies of the western phosphate industry and its potentialities. These included an appraisal of the opportunities for western development of the industry, studies of production costs, of market potentials, of transportation economics, and of industry location. This paper will be directed toward pointing up the factors which have an important bearing on the establishment of fertilizer plants in the western area. Industry Location Factors: There are, of course, an infinite number of possible organizational setups which might require consideration. However, the phosphate industry is simple enough so that studies of the most probable alternatives can be made conveniently. The salient factors which require special consideration in such a study are: (I) the location of the raw materials, (2) the location, size, and character of the present and potential markets, (3) the location of energy sources and materials required for fertilizer processing, (4) the location and capacity of present manufacturing facilities, (5) the cost of assembling the materials and energy needed in manufacturing, and (6) the cost of distributing the manufactured product. Raw Material Supplies: Rock phosphate is the raw material for the manufacturing of phosphate fertilizer. In the United States the important known deposits of this material are located in three general areas (fig. 1). The western deposits, comprising about 60 pct of the nation's supply, are in the four-state area—Idaho, Wyoming, Utah, and Montana. The Florida deposits comprise roughly 38 pct of the national supply. The Tennessee deposits, comprising about 2 pct of the national supply, have been the most important source until recent years. The western deposits, which are virtually undeveloped, have not been used to any extent to meet the nation's need for phosphate rock and phosphate fertilizer. Fertilizer Markets: The large national markets for fertilizer are in the midwestern and eastern United States (fig. 2). The principal far-western markets are along the Pacific Coast, especially in California. Until recent years the western markets have been extremely limited, whereas the markets in the eastern United States have long been established and manufacturing facilities have been provided to meet these needs (fig. 3). In recent years the western markets have expanded very rapidly, continuing to grow throughout the war years and postwar period at a similar rate. The question always arises as to whether this is a temporary war-swollen market which will shrink back to its original size as soon as the present agricultural price levels drop. In order to answer this question consideration must be given to the character of the market (fig. 4). I have considered seventeen western and midwestern states in the western market area where transportation costs from the western deposits are equal to or lower than those from Florida. They include all states west of a line drawn through Chicago, Kansas City and the western boundary of New Mexico. In the mewar period this was a small market totaling only 37,000 tons of P,O, annually. The 1946 total for this same area was approximately 200,000 tons. Considerably more fertilizer would have been used in 1946 had adequate supplies been available. Estimates of future markets are difficult to make, but we do have some indices that are useful. The

Jan 1, 1951

By Roscoe E. Bell

BETWEEN 1945 and 1948 the author made studies of the western phosphate industry and its potentialities. These included an appraisal of the opportunities for western development of the industry, studies of production costs, of market potentials, of transportation economics, and of industry location. This paper will be directed toward pointing up the factors which have an important bearing on the establishment of fertilizer plants in the western area. Industry Location Factors: There are, of course, an infinite number of possible organizational setups which might require consideration. However, the phosphate industry is simple enough so that studies of the most probable alternatives can be made conveniently. The salient factors which require special consideration in such a study are: (I) the location of the raw materials, (2) the location, size, and character of the present and potential markets, (3) the location of energy sources and materials required for fertilizer processing, (4) the location and capacity of present manufacturing facilities, (5) the cost of assembling the materials and energy needed in manufacturing, and (6) the cost of distributing the manufactured product. Raw Material Supplies: Rock phosphate is the raw material for the manufacturing of phosphate fertilizer. In the United States the important known deposits of this material are located in three general areas (fig. 1). The western deposits, comprising about 60 pct of the nation's supply, are in the four-state area—Idaho, Wyoming, Utah, and Montana. The Florida deposits comprise roughly 38 pct of the national supply. The Tennessee deposits, comprising about 2 pct of the national supply, have been the most important source until recent years. The western deposits, which are virtually undeveloped, have not been used to any extent to meet the nation's need for phosphate rock and phosphate fertilizer. Fertilizer Markets: The large national markets for fertilizer are in the midwestern and eastern United States (fig. 2). The principal far-western markets are along the Pacific Coast, especially in California. Until recent years the western markets have been extremely limited, whereas the markets in the eastern United States have long been established and manufacturing facilities have been provided to meet these needs (fig. 3). In recent years the western markets have expanded very rapidly, continuing to grow throughout the war years and postwar period at a similar rate. The question always arises as to whether this is a temporary war-swollen market which will shrink back to its original size as soon as the present agricultural price levels drop. In order to answer this question consideration must be given to the character of the market (fig. 4). I have considered seventeen western and midwestern states in the western market area where transportation costs from the western deposits are equal to or lower than those from Florida. They include all states west of a line drawn through Chicago, Kansas City and the western boundary of New Mexico. In the mewar period this was a small market totaling only 37,000 tons of P,O, annually. The 1946 total for this same area was approximately 200,000 tons. Considerably more fertilizer would have been used in 1946 had adequate supplies been available. Estimates of future markets are difficult to make, but we do have some indices that are useful. The

Jan 1, 1951

EUGENE WESLEY SHAW,* Washington, D. C. (written discussion?).-Mr. Requa's subject is one of great economic importance, yet relatively new, and he has been able to combine extensive practical experience with the talent of grasping the broad features of a problem that has many discordant details.

Jan 5, 1918

By B. D. Smith, K. H. Coats

Experiments in which calcium chloride displaced sodium chloride from four cores showed the extent of asymmetry in the resulting effluent concentration profiles. These results provided a check on how validly the mixing process is modeled by a differential (i.e., not finite-stage) capacitance mathematical model. The effluent concentration profile from two consolidated cores exhibited considerable asymmetry, while two unconsolidated cores yielded nearly symmetrical profiles. All runs resulted in breakthrough of the 50 per cent concentration significantly before one pore volume was injected. In addition, velocity appreciably affected the effluent concentration profile from a Torpedo sandstone core. The differential capacitance model matched the data significantly better than a simple diffusion model. The capacitance model allows determination of the amount of dead-end pore space in a porous matrix and the effect of velocity on the rate of diffusion into this space. An experimental program yielding insight into the physical validity of the capacitance effect is described. INTRODUCTION Axial dispersion — the mixing accompanying the flow of miscible fluids through porous media — has been the subject of many relativeiy recent studiesl-13 and a comprehensive review of the topic has been given by Perkins and Johnston.14 This dispersion is of practical interest in studies of the miscible displacement process, fixed-bed chemical reactors, and the adsorption of solutes from a flowing stream onto the surface of a porous medium. In the latter case, the effect of dispersion must be considered when adsorption parameters are determined from the nature of concentration profiles. In general, early studies of dispersion assumed applicability of a simple diffusion equation and were concerned with correlation of the experimentallv determined "effective" diffusion coefficient with system properties over a large range of the latter. Recent have been concerned with the deviations between the asymmetrical effluent concentration profiles observed and the symmetrical ones predicted by the diffusion model. In the present study, effluent concentration profiles were obtained from consolidated and unconsolidated cores. These profiles were compared with those predicted by a differential (i.e., not finite-stage) capacitance model. Solutions to the simple diffusion model, for three sets of boundary conditions, were compared with one another and with the experimental profiles. SUMMARY OF PREVIOUS WORK The reader is referred to Perkins and johnston14 for an extensive review of studies of dispersion in porous media. Many investigators have employed the simple diffusion model characterized by Eq. 1 below: The dispersion coefficient D for unconsolidated systems is correlated by u is interstitial velocity and dp is particle diameter. Since heterogeneity of the sand pack affects the mixing, this equation is also expressed as where a is proportional to the degree of heterogeneity and is about 3.5 for random packs of unconsolidated sand.l4 Eq. 3 holds for 2 For a Do homogeneous (regular) type of packing, should be 1 or less.6 Aris and Amundson6 and Carberry and Bretton consider o to be the number of particle lengths per mixing cell in the finite-stage model. Data from consolidated cores indicate dp to be about 0.36 cm for outcrop rocks, Torpedo sandstone having a reported value of 0.17 cm.15 For v /Do less than about 2, the effect of molecular diffusion must be considered and the total dispersion coeffi-

Jan 1, 1965

By D. J. Carney, J. Chipman, N. J. Grant

G. A. Moore—The tin-fusion method has been a very favorable possibility for many years. The authors apparently have settled the question that delayed the method for a long time by showing that no hydrogen is absorbed in the tin. This, of course, is very important. I want to make a few remarks concerning the absolute accuracy of analysis, which must be the final basis for deciding among the various methods. From the figures in the paper, there seems to be some remaining slight discrepancy on the actual amount of hydrogen present in various samples which may be presumed essentially identical. (This is of the order of the precision of individual analyses but appears in averaged results.) From the analyst's viewpoint, the tally of hydrogen content can be regarded as occurring in three portions. First is a large portion which comes off easily and automatically during sample storage and later on heating in the apparatus. This is fairly easily analyzed. Second is an item which may be either positive or negative in the tally sheet. In warm or hot evolution, this is a portion which, in practice, can never be re-

Jan 1, 1951

By MORTON WEBB

Discussion of the paper of Max Boehmer, presented at the Pittsburg meeting, March, 1910, and printed in Bulletin. No. 38, February, 1910, pp. 119 to 122. W. MORTON WEBB, Germiston, Transvaal, South Africa (communication to the Secretary*):-The experience of Mr. Boehmer in the Leadville district and his reputation as an engineer assure the interest of anything he may write on the ore-bodies of that district; and all engineers who have operated in Leadville will agree that the theory of the origin of the Leadville deposits, as given by Mr. Emmons in his famous monograph, does not adequately explain the genesis of all the deposits. The solution of the problem does not, however, appear to be quite so simple as Mr. Boehmer would make it; and the advance pamphlet issued by the U. S. Geological Survey, pending the completion of the main report, shows that there is still much ground for controversy. No doubt the later eruptives had a greater influence on the deposition of the ore-bodies than was thought at the time of the first investigation by the Survey; but it has always appeared to me that the influence exerted by these dikes was more in the nature of a physical than a chemical one. The weight of evidence in recent years is mostly in the direction of ascension rather than lateral secretion; and one of the strongest evidences is the fact that most of the ore-bodies lie under one of the comparatively impervious layers which help to make up the structure of these hills. On Iron hill I have found a very persistent white porphyry sheet, split off from the overlying porphyry and lying from 30 to 60 ft. below the main white porphyry and blue limestone contact. This sheet varies from a few to 50 ft. in thickness, and where found adds another "contact" to that region ; some of the largest ore-bodies on Iron hill lie immediately under this sheet. Above this is the main white porphyry and * Received Mar. 3, 1910.

Feb 1, 1911

By Charles Hart

A STUDY of the various ores that have been discussed impresses one with the need of beneficiation, in many cases. This applies to the ores that have lain dormant, due to necessity for further preparation, or to ores that now find a market due to a changed condition. Processes of beneficiation will come into their own as our richer ores become exhausted. Many efforts at improvement have been commercial failures, due to prematurity. Thomas A. Edison, with characteristic foresight, attempted concentration of the low- grade New Jersey magnetites some thirty years ago. Due to high costs and the discovery of the Mesabi range, his efforts were futile. However, a successful crusher, designed by Mr. Edison, resulted from this attempt. Agglomeration of concentrates had not, at that time, been brought to its present efficiency, when sinters and briquettes of excellent physical condition are obtainable. Recent efforts in the beneficiation of the lean magnetites of the East Mesabi resulted in an excellent sinter, but that operation is also ahead of its time.

Jan 1, 1929

By Mark J. Klein

An internal-friction profile induced by nitrogen in Cr-35 at. pet Re was studied as a function of nitrogen concentration and heat treatment. From these studies, the solubility of nitrogen in this alloy was deduced. The equilibrium solubility of nitrogen in chromium does not appear to be substantially changed by the addition of 35 at. pet Re to chromium. However the precipitation kinetics of nitrogen from solution are significantly decreased. IT has been found that rhenium has a beneficial effect on the low-temperature ductility of Group VI-A metals. As part of a study to investigate the mechanism of this increased ductility, it was of interest to compare the concentration of interstitials retained in solution in one of these ductile bee alloys with the concentration retained in solution in its base metal. In this regard, a study of the solubility of nitrogen in ductile Cr-35 at. pet Re was selected for this phase of the investigation because the solubility of nitrogen in the base metal, chromium, has been determined over a fairly large temperature span.1-3 In addition, nitrogen is known to have an embrittling effect on chromium,4 but does not appear to have a comparable embrittling effect on Cr-35 at. pet Re.5 The experimental method selected for this study was the measurement of internal friction. This technique allows interstitial-concentration measurements to be made in bee metals that are sensitive to small changes in the concentration of a particular interstitial, even when other interstitials are present. When subjected to a cyclic stress, interstitial atoms in solid solution give rise to an internal-friction peak whose origin is the stress-induced ordering of interstitials into preferred lat- tice sites. These internal-friction peaks signify a dissipation of elastic energy which is greatest when the period of oscillation is comparable with the relaxation time for the attainment of an equilibrium interstitial distribution. For dilute interstitial binary alloys, the height of the internal-friction peak is proportional to the concentration of interstitial atoms in solid solutions. snoek8 has shown that the internal friction, Q-1, may be expressed by the equation where A is the relaxation strength, ? is the angular frequency, and 7 is the relaxation time. The relaxation strength, A, is proportional to the concentration of interstitials taking part in the relaxation if no interaction occurs between solute atoms. Thus values of peak height, which can be determined as a function of temperature, give a measure of the relative concentration of interstitial atoms in solution at various temperatures. If equilibrium has been attained, the peak heights will be proportional to the interstitial solubilities. The constant that relates A to the interstitial concentration can be determined experimentally from peak-height measurements as a function of concentration for specimens of constant crystallographic orientation. When this has been done, Q-1 measurements can be used to determine solubilities according to the equation C - KQ-1 where C is the soluble interstitial concentration and K is a constant that can be experimentally determined. It is possible, however, that lattice imperfections may bind interstitials to certain lattice sites. Internal friction does not measure these interstitial~, but does measure interstitials which are free to move in the normal lattice sites when subjected to an applied oscillating stress. On alloying the pure metal with a substitutional

Jan 1, 1965

By J. F. Breedis

The morphology and crystallography of marten -site formed during quenclzing were examined by transmission electron microscopy in alloys whose compositions lie between Fe-19 wt pct Cr-11 wt pet Ni and Fe-33 wt pet Ni. Depending upon composition, four types of transformation products were observed in this portion of the Fe-Cr-Ni system. Three of these products are denoted as lath, plate, and surface martensite. The hcp structure found in association with martensite it? certain higlz-clzromium stairzless steels does not influence the transformation crystallogyaphy and cannot he Considered to act as a transitional structure in the transformation from austenite to martensite. DISTINCT changes in the characteristics of mar-tensitic transformations are produced by the partial replacement of nickel by chromium in austenitic iron alloys. Large, discrete martensite plates form in Fe-30 pct Ni, while aggregates of small crystals form in sheets parallel with (111)A austenite planes in stainless steels containing in the vicinity of 18 pct Cr and 8 pct Ni. These transformation structures are termed plate and lath martensite, respectively. In addition, an hcp structure (E) has been observed in certain high-chromium stainless steels in association with martensite. It has been suggested that the E structure acts as an intermediate step in the nucleation of martensitel-' and influences the morphology and crystallography of the final transformation product. However, this structure may be the consequence of the deformation of austenite arising from the shape distortion accompanying the transformation to bcc martensite.' An hcp stacking of atoms is produced in an fcc lattice by the introduction of an intrinsic stacking fault on alternate (111)A planes. At present, the arguments behind each explanation for the E structure are based on circumstantial evidence. This investigation seeks to determine the importance of the hcp structure to the martensitic transformation, and to examine the crystallography and morphology of the structures produced in bulk samples by quenching in alloys whose compositions lie between Fe-19 wt pct Cr-11 wt pct Ni and Fe-33 wt pct Ni. These aspects of the martensitic transformations occurring in these alloys have been studied by electron metallography and selected-area diffraction of foils examined in transmission in the electron microscope. EXPERIMENTAL METHODS The alloys have been prepared from thoroughly mixed powders of pure iron (99.6+ pct, 0.06 max pct C, 0.15 max pct N), chromium (99.9+ pct), and nickel (99.9+ pct). After sintering in an Ar-H2 atmosphere, the mixtures were melted by induction heating in recrystallized alumina boats under purified argon. The ingots were cold-rolled to 0.4-mm sheets (100 pct reduction in thickness) after the removal of at least 1.5 mm from their surfaces by grinding. Three-millimeter discs were punched from the cold-rolled sheet and annealed at 1150°C for approximately 24 hr in evacuated quartz capsules. The average grain size was 40 µ Thin foils for examination in transmission in the electron microscope were prepared from discs quenched to liquid-nitrogen temperature. A depression was first jet-machined into the center of a disc and a thin area (less than approximately 3000A in thickness) was produced at the base of the depression by electropolishing. Electron-microscope studies utilized the RCA EMU-3 and the Philips EM-100B microscopes operating at 100 kv. X-ray examination of the polycrystalline alloys was performed either in a diffractometer or in a

Jan 1, 1964

By H. H. Rachford, W. P. Schultz

The use of computing machines to solve physical problems has made it imperative to represent physical data in a form computing machines can use. Although curve-fitting is an old and well-practiced art, there still seems to be some interest in questions regarding what methods can be used and why. Even though there are many good references on this subject, it may be of some value to discuss a particular method which has been found to be useful, and to make available the associated tables for its use in the hope that there can be saved a few of the tedious hours necessary to reduce many of the suggested methods to practice. Although a very brief discussion of the mathematical background of the tables is included immediately below, those interested only in their use can skip directly to the section on Use of the Tables. Direct Fit of a Set of Points A frequently encountered problem is: Given data which can be represented by a smooth curve +(x), to find an easy-to-evaluate function F(x), with only a few coefficients, which is a good approximation of +(x) on the interval 0 5 x 5 x,,. Consider F(x) as a linear combination of m + 1 arbitrary, single-valued, continuous, linearly independent functions, f,(x), Ff.r) = a,f,,(x) + a,f,(x) + . . . -+ aifi(x) + If the value of Q(x) is known or can be read from the curve at the points xj: +(x,), +(x,), . . . +(xj) . . . +(x.), and if n = m, then all the coefficients of F(x) can be determined, and F(x,) — +(x,) = 0 for j =. 0, 1, . . . n. This follows from the solution of the set of linear simultaneous equations. +(x<.) = aofu(x,) + aJI(x0) + . . . + a,,f,,(x,) =a, = f,,(x,) + a,f,(x,) + . . . + a,f,,(x,) +(x,,) = a,,f,(x,,) + a,f,(x,) + ... + a,,f.,(x,,) ...........(2) for the coefficients ai. Although the set a, from the solutions of the set of Equations 2 yields an fix) which gives an exact value of $(x,) for the n + 1 points, there is no restraint on ~(xj in the interval xi < x < xj+,. Indeed, if the points +(x,) are not sufficiently smooth, very serious differences may arise between F(x) in the interval and the smooth curve +(x). Least-Squares Fit It has been suggested&apos; that if n is made to exceed m, and the set a, is found to minimize the function the function F(x) is much less sensitive to small errors in +(xi), and usually provides a much better fit to the smooth function +(x). This is known as the best fit in the sense of the least-squares error. To minimize $, set £ = 0,i = 0,1,... iTi,.....(3) The m + 1 equations from Equation 3 are k—n k=n a.^p /,,(a) f,(xt) + a, X A: = 0 k=O k = n k = n k=0 k=0 +(x.) f,(x,),............(4) one equation being obtained for each i = 0, 1, . . . m. Inasmuch as the arbitrary functions f(x) may be evaluated for x,, k = 0, 1, . . . n, and the +(x,) are known values of the curve to be fitted, the simultaneous Equations 4 may be solved for the set a,. Particular Functions Given the functions fi(x) and the set +(xj), the solutions for require evaluating a number of sums of products as well as the solution of an m + 1 order set

Jan 1, 1956

By R. M. Jorda

The mechanism of parafin deposition and prevention has been studied in the laboratory using an apparatus which provides a quantitative means of studying parafin deposition on metal and plastic surfaces. The amount, hardness, adhesion, per cent wax and mean molecular weight of parafin deposits appear to be governed by surface roughness alone, all other conditions being constant. Tests of various plastic coatings indicate that most smooth, nonparafinic plastics are capable of reducing parafin deposits in oil wells, but flexible, highly polar, nonparafinic plastics are more suitable for providing long term resistance to parafin deposition in oil wells if the flow stream contains abrasive materials. INTRODUCTION The problem of paraffin deposition is one of long standing in the oil industry.&apos; Crude oils often contain paraffins which precipitate and adhere to the liner, tubing, sucker rods and surface equipment as the temperature of the producing stream decreases in the normal course of flowing, gas lifting or pumping. Heavy paraffin deposits are undesirable because they reduce the effective size of the flow conduits and restrict the production rate from the well. Where severe paraffin deposition occurs, removal of the deposits by mechanical, thermal or other means is required, resulting in costly down time and increased operating costs. The troublesome paraffins are normal hydrocarbons ranging from approximately C15H38 to C38H78 mixed with small amounts of branched paraffins, monocyclic paraffins, polycyclic paraffins and aromatics.&apos; The amount of paraffins found in crude oils varies from less than 1 to more than 30 per cent. Many publications are available which deal with this problem, and perhaps the most significant findings in recent literature are contained in a publication by Hunt3 ho developed the "cold spot tester", a really useful means of investigating paraffin deposition. Hunt&apos;s observations led to many generalized conclusions concerning the effect of surface roughness on paraffin deposits. He ascertained that there was an observable qualitative correlation between the severity of paraffin deposition and the roughness of the surfaces which he tested (cold rolled steel, stainless steel and several plastics). Because of the number of meaningful observations made by Hunt, his cold spot tester was modified somewhat and extensive tests were per- formed to study the quantitative relationship between surface roughness and the physical and chemical nature of paraffin deposits. LABORATORY TEST PROCEDURES The cold spot test apparatus consists of a flat circular plate mounted on a curved tube and positioned in a vessel containing a wax-oil solution (Fig. 1). The apparatus is arranged so that the temperature of the central portion of the circular plate can be varied by means of a circulating liquid stream; the test equipment includes provisions for maintaining a constant wax-oil solution temperature and stirring speed. In the paraffin deposition studies, the modified cold spot tester was used as follows. The cold spot probe consisted of a flat circular plat 2 in. in diameter and 1/8-in. thick positioned in the wax-oil solution kept at constant temperature. As in Hunt&apos;s earlier experiments," a cold liquid was circulated through a tube connected to the circular plate so that the liquid impinged on one side of the plate cooling the plate from the center outward, causing paraffin to deposit on the side of the plate exposed to the wax-oil solution.

Jan 1, 1967

By RICHARD MAIZE

IN this critical period of our history, the coal industry of the nation, faced with many obstacles, performed its work safely during the first ten months of 1943. Thousands of the younger mine workers were inducted into the armed forces of our country and in many instances their jobs have been filled by others without much if any experience and training. This situation alone would seem to be sufficient to interfere with the safe and orderly operation of the industry but the Government&apos;s demand for a substantial increase in coal tonnage over that produced in normal times introduced a hazard which always accompanies speed, regardless of the skill of the worker.

Jan 1, 1944

By Harry L. Brown, Philip E. Armstrong

Young&apos;s modulus doto ore presented for W, Mo. Ta. V, Cr. Ni, Ti, and Zr as a function of temperature up to about 0.7 of the melting points. A plot of reduced temperature us reduced modulus produces a general correlation except for titanium and zirconium. Young&apos;s modudlus data for some representatiue commercial graphites are given up to 2400°C. All results were obtained from longitudinal resonance-frequency measzrrements of 4-in. long samples, corrected for simultaneously measured thermal expansion. Comparison of poly crystalline and single-crystal tungsten behavior indicates that all the observed modulus values are frequencv -dependent at the higher temperatures. STATIC measurements of elastic properties of materials at elevated temperatures are extremely difficult to make since the elastic behavior is obscured by relatively large first-stage creep effects. Dynamic methods which avoid this difficulty by utilizing the measurement of the resonance frequency of a simple vibrational mode have been described in the 1iterature.l-3 The authors have extended the operating temperature range of this type of measurement to above 2000°C and have described the equipment elsewhere.~ The Young&apos;s modulus data presented here were obtained with this equipment, using samples about 4 in. long and 1/4 in. diam, supported horizontally at the center and excited to the fundamental longitudinal resonance frequency. Young&apos;s modulus was calculated by the formula: E = 4f2f2p where E = Young&apos;s modulus, / = frequency, 1 = length, and p = density. Dilatometric data were obtained simultaneously by optical measurements of the change of length of the sample. For the metals tested, an attempt was made to obtain modulus values that would be representative of the pure, strain-free, randomly oriented material. All of the graphites studied exhibited a high degree of elastic anisotropy, while the method assumes an isotropic homogeneous material. However , when the values for Young&apos;s modulus obtained for AUC graphite were compared with those taken from static measurements at room temperature they were found to be only about 4 pet higher. This is excellent agreement considering the low precision of modulus calculations from stress-strain curves. The difficulty in using data of apparent Young&apos;s modulus for anisotropic materials arises when the attempt is made to use these data and shear-modulus data to obtain Poisson&apos;s ratio. The results are usually meaningless and sometimes absurd.&apos; RESULTS Table I lists the sources, impurity content, thermal history, and dilatometric constants of the metal samples that were investigated. All the metal samples were tested under a vacuum of 1 to 5 x 10-5 Torr. Where our dilatometric data agreed with previously published data, the table lists the previous values and the literature reference. Where no reference is given, the constants were determined from our dilatometric data. Table II presents the modulus data in units of millions of psi as a function of temperature in degrees centigrade. The numbers were obtained from curves fitted to the experimental data. For some types of calculations, such as those attempting to correlate creep data, the slope of the modulus curve is of interest, and this information also is reported in Table 11. It is always tempting to try to fit physical-property data into some general pattern and then use this pattern to predict the behavior of other similar materials. The general pattern for an elastic modulus of a metal seems to be a linear deoro- with increasing temperature Over the range between 0.1 and 0.4 of the melting temperature, then a progressive1y decreasing value up to the melting point. Metals appear to retain finite moduli

Jan 1, 1964

By AIME AIME

IN an address before the New York Section. A.I.M.E., Oct. 20, Alex L. ter Braake, speaking on the tin industry of the Netherlands East Indies, interjected a few remarks, at the chairman&apos;s request. on the mineral stock-piling project now before Congress in a bill sponsored by Senator Scrugham. The full text of Mr. ter Braake&apos;s paper was published in the Nov. 6 issue of the American Metal Market. Following mention of the buffer stock scheme as applied in the tin industry, Mr. ter Braake continued:

Jan 1, 1943

By W. L. Falke, A. A. Cochran

A basic problem in connection with manganese is to find economical ways to utilize domestic resources. As a part of its program to conserve domestic mineral resources and to reduce dependence of foreign sources, the Bureau of Mines had conducted extensive research to broaden manganese technology and to find economical, technically-feasible processes for recovering manganese from these low-grade resources. This paper analyzes some of the major difficulties which have been encountered in previously proposed processes for treating low-grade manganese ores and discusses a process which may circumvent many of these difficulties. Vast deposits of low-grade manganese ore exist in the U.S., yet domestic production is insignificant compared to the more than 2 million tons of ore imported yearly into this country.&apos; A basic problem in connection with manganese is to find economical ways to utilize domestic resources.2 As a part of its program to conserve domestic mineral resources and to reduce dependence on foreign sources, the Bureau of Mines has conducted extensive research to broaden manganese technology and to find economical, technically feasible processes for recovering manganese from these low-grade resources. Although a great many processes have been proposed for treating domestic manganese resources, a failing of many of them is that too many steps are involved for economical operation.&apos; Some of the major processes that have been proposed were reviewed by Norman and Kirby.3,4 Chlorination processes have become increasingly useful as a means of recovering valuable metals from raw materials, because the relative cost of chlorine (Cl2) and hydrogen chloride (HC1) has decreased through the years, and because the corrosion resistance of materials of construction has been improved. The objective of these processes is to form metal chlorides that are more volatile or water-soluble than are the corresponding oxides or sulfides; these compounds then can be separated from the gangue or other minerals by volatilization or leaching. Several chlorination processes for the recovery of manganese have been investigated by the Bureau of Mines5-8 and others; the major chlorination processes were reviewed in 1963, and their main features were compared.4 In all these processes, the simultaneous leaching or volatilization of iron chlorides with manganese chloride (MnCl2) is a problem, and the more iron that is present, generally the greater the problem. The leaching step is not highly selective, and the product of this step is, at best, suitable only for the production of ferromanganese or for further processing to remove iron. The product of the volatilization step is, in all cases, a mixture of iron and manganese chlorides that contains too much iron even for ferromanganese production, and must undergo additional processing steps for iron removal. THERMODYNAMIC CONSIDERATIONS The literature indicates that the desired chlorination reactions will proceed at practical rates at temperatures near 1200°K (927°C). Free energy changes at 1200°K for the critical steps of the reduction and chlorination reactions9-11 follow: Most of the research on chlorination processes for manganese recovery has been done with HC1 rather than with C12, for the following three main reasons: 1) Recycling of the chlorinating agent, which is economically vital, appeared to be easier for HC1

Jan 1, 1968

By H. D. Yoo, M. R. Tek, D. L. Katz

The behavior of gas-storage reservoirs subject to water drive is investigated through analog simulation on an electronic differential analyzer. The simulation technique developed on an LM-10 computer permits the prediction of reservoir volume or pressure resulting from the movement of water in the surrounding aquifer. The method developed on the analog computer consists of setting up an appropriate transfer-function circuit and feeding the arbitrary time-varying boundary conditions as an input signal. The input may be specified as gas reservoir pressure, pore volume or the water flux. Several cases studied include an isolated gas reservoir on a limited aquifer, interference among three reservoirs adjacent to a common aquifer and the growth of gas-storage volume on an aquifer. It is concluded that the method developed on an electronic differential analyzer provides an excellent technique to simulate and investigate the behavior of gas reservoirs subject to water drive. The agreement between the reservoir performance as predicted from the simulation technique and as measured from actual field data is found to be better than the range usually encountered in predicting water-drive behavior. INTRODUCTION It is generally known that some gas-storage reservoirs are located on top of blanket sands of large extent, saturated with brine called aquifers. Because the volume of the body of water associated with aquifers is usually very large and water is compressible, the cyclic pressure variations encountered in normal storage service inevitably cause unsteady, compressible flow conditions in the adjacent aquifers. The solution to radial diffusivity equation for a limited aquifer for constant terminal conditions has been know111 since the early 1930&apos;s. The solution for the constant terminal conditions for an infinite aquifer was puhlished in 1949.2 The proldem of handling the unsteady flow of water through a porous medium with time-varying boundary conditions has been studied by many investigators through the use of graphical,3 digital4 computing techniques or on an R-C type of electrical analog called a reservoir analyzer.5 The digital computer performs a series of arithmetic calculations to superimpose the solutions of constant terminal conditions, while the R-C type of analyzer permits the simulation of the continuous medium by means of "lumped-cell" electrical resistance and capacitance elements based on finite-difference approximations. The graphical method is based on the convolution integral solution of the partial differential equalion. The purpose of the present study was to simulate the behavior of an aquifer on a general-purpose, electronic differential analyzer to obtain the influx of water or the change in pressure at the reservoir continuous1r and quickly. The use of the electronic differential analyzer was based on well known solutions for the constant terminal conditions already available in the literature.2,6-8 THEORETICAL DEVELOPMENT MODEL. The gas reservoir (R) is described in relation to an aquifer in Fig. 1. The permeability and porosity of an aquifer sand, the viscosity of the brine, and the compressibility of the brine and the formation are assumed to be constant. It further is assumed that the blanket sand is not thick enough to give appreciable vertical pressure distribution. The model in consideration is circular with radial geometry. The aquifer radius can be of limited or infinite extent. The gas-water interface is assumed to be fully segregated, and the displacement of the gas by

[1-Iron and Steel JOHN A. MATHEWS, Chairman RALPH H. SWEETSEH. Vice-chairman WILLIAM CAMPBELL. Vice-chairrmn MAX ROESLER, Secretary Iron Ore R C. ALLEN W. 0. HOTCHKISS MAX ROESLER ERNEST F. BURCHARD THOMAS T. READ DWIGHT E. WOODBRIDGE M. M. DUNCAN WILLIAM KELLY CARL ZAPFFE]

Jan 1, 1928

[OFFICERS AND COMMITTEES J. W. Woomer, President A. B. Cummins, President-elect S. D. Michaelson, Past President C. E. Lawall, Eastern Regional Vice-President D. W. Scott, Central Regional Vice-President J. D. Forrester, Western Regional Vice-President R. B. Ladoo, Treasurer John Cameron-Fox, Secretary]

Jan 1, 1961