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By James Magee

THERE is nothing new about drag-line dredging for placer gold. The use of the separate unit for excavating preceded the large barge with excavator mounted upon it, which has reached a high state of perfection through use in every part of the world. But at present there is a vogue for a small, inexpensive plant combining a drag-line excavator on cater-pillar mounting and a gravel-washing plant on a floating barge. The most efficient ones use a bucket of 1 to 2 yd. capacity with boom from 40 to 70 ft. long. The barge varies from 20 by 30 ft. to 36 by 48, and carries the trommel screen, pump, riffle sluices and power engine.

Jan 1, 1936

By M. E. de Morton

Low frequency-internal friction measurements on annealed chromium have shown a marked increase in damping below - 40°C which is strongly strain amplitude dependent. An interpretation of these results is given in terms of the motion of antiferromagnetic domains assumed to exist below - 40°C. A time effect on internal friction was measured after slight overstraining. After heavy deformation a pemzanent, five-fold increase in internal friction was observed at -45°C and the character of the internal friction us temperature curve markedly changed. Full recovery of damping was not attained until after heating to 800°C. A qualitative interpretation of some of these effects is given. THE aim of this preliminary investigation was to study the internal-friction characteristics of chromium containing comparatively small quantities of interstitial solutes in the fully annealed and heavily worked condition. Marked anomalies in a number of physical properties of chromium at temperatures near 40°C have been observed1 and an investigation by neutron diffraction' has shown that chromium at room teyperature is weakly antiferromagnetic with a Nee1 temperature at approximately 200oC. No irregularities in the degree of antiferromagnetic ordering have been observed at -40°C, the transition temperature, and a complete explanation of this transition in chromium is still awaited. Recently weiss3 has suggested that an ordering effect of nitrogen in the face-centered interstices of the bcc lattice of chromium could be responsible for the superlattice detected below 200 °C in the neutron diffraction experiments. EXPERIMENTAL MATERIAL AND METHOD Specimens 10 by 0.030 in. diam were prepared from ingots of arc-melted electro-deposited chro-

Jan 1, 1961

By Wilbur Stout

IN Ohio, the annual output of coke made from native coals has averaged not more than 70,000 tons, or about enough to run a 200-ton blast furnace. Raw coal locally mined from the Sharon, or No. 1, bed was used for iron smelting in Mahoning furnace at Lowellville, Mahoning Co., as early as 1846. This practice was continued in the Youngstown district until the coal became scarce and the Connellsville coke more popular. At present, the Sharon bed contributes a part of the fuel for the production of ferrosilicon iron at Jackson, Jackson Co. About one-third native coal and two-thirds soft coal are used. In this state, coke, on a commercial basis, was first made in Jefferson County probably about 1861 or 1862. The coals used were the Steubenville Shaft, or Lower Freeport, and the Strip Vein or Middle Kittanning. The practice, however, was discontinued before 1880 because of the competition of superior foreign cokes. Beehive ovens, later built at Leetonia, Columbiana Co., were operated for only a few years; the coal used at this place is the Lower Kittanning or No. 5. In a desultory way, slack from the Pittsburgh coal has been coked at a few places in eastern Ohio, and attempts, either for experimental or for commercial purposes, have been made in other parts of the State. Small quantities of coke were made from the Upper. Freeport coal at Salineville, Columbiana Co., and near Nelsonville, Hocking Co.; the results were poor. Tests were made of the Middle Kittanning coal near Zanesville, Muskingum Co., at Moxahala Furnace, Perry Co., and at Washington Furnace, Lawrence Co.; the cokes were all high in sulfur and ash. Attempts were made to coke the Clarion coal at Vinton Furnace, Vinton Co.; a small battery of molding ovens and a pile of high-sulfur coke yet remain to tell the story. The Pittsburgh coal was coked on a commercial scale at Utley and at Lathrop, Athens Co.; but the operations were not successful and were soon abandoned.

Jan 9, 1919

By Frank Speller

WE are here to honor again the memory of Henry Marion Howe, one of the foremost metallurgists of his time, and it is indeed a great privilege to be called upon by the Board of Directors of .this Institute to give the memorial address this year. Professor Howe started active investigation of corrosion of iron from a metallurgical standpoint in 1887, and made several important contribu-tions to the subject from 1895 to 1908.(1) ? The papers named in the bibliography are only a few of his valuable papers, but in all his works he sets a high standard of scientific accuracy, together with a clearness and power of expression rarely equaled in engineering literature. There-fore it seems appropriate on this occasion to review the work on corrosion of this distinguished gentleman and then endeavor to make a brief inventory of what has been accomplished since his time. Howe saw the beginning of the steel industry in America and before he died (May 14, 1922) witnessed it develop to a production of 45,000,000 tons per year. He was naturally very much interested in the infant industry and was quick to see the importance of the question of corrosion. It was my privilege to discuss the subject of corrosion frequently with Professor Howe at various times from 1905 to 1908; in this, as in other metallurgical problems, he sought the truth without bias and always insisted on proving an opinion or conclusion before accepting it. We should remember that when Howe started his investigation of corrosion, in 1887, steel was rapidly supplanting wrought iron. Certain papers in the early eighties (now forgotten) claiming much greater durability for wrought iron than for steel aroused Howe's interest. He could not reconcile the statement that steel was intrinsically and incurably less durable than wrought iron with the continued and widening use of steel,

Jan 1, 1934

By V. H. Wilhelm

During the first half of the year 1935, the oil industry in California was on a fairly profitable basis, owing mainly to the operation of the Petroleum Marketing Agency. Coincident with the discontinuance of enforced curtailment, California production surged upward from an average of about 500,000 bbl. per day (over the first five-month period) to approximately 625,000 bbl. per day (over the last seven-month period). On Dec. 9 the state production had reached a peak of over 700,000 bbl., a figure that had not been approximated since the early days of voluntary curtailment (Fig. 1). A price cut was instituted during the last half of August, but had no deterring effect on operators that were determined to take advantage of the breakdown of curtailment and produce to capacity. New reserve figures, compiled from actual potentials, available after cessation of curtailment, revealed the startling fact that California reserves were rapidly declining. This situation, coupled with the desire among operators to obtain a more equitable price for their dwindling reserves, caused a restoration in November of a portion of the August price slash. A further rise in price was effected in early December, and crude quotations at the end of the year closely approximated those in effect during the first right months. At the close of the year, the industry felt confident that the production situation was under control. In all fields where competition is keen because of close spacing, production is gradually declining. In the Los Angeles Basin especially there is no likelihood of a large amount of overproduction, unless a new pool is discovered or deeper drilling reveals a prolific source of crude. As long as the fields that are operated by a few companies, such as Kettleman Hills, North Belridge, Ventura Avenue, West Coyote, Dominguez, and some others, can be controlled, it is believed that the overproduction problem in California will be solved.

Jan 1, 1936

By V. H. Wilhelm

During the first half of the year 1935, the oil industry in California was on a fairly profitable basis, owing mainly to the operation of the Petroleum Marketing Agency. Coincident with the discontinuance of enforced curtailment, California production surged upward from an average of about 500,000 bbl. per day (over the first five-month period) to approximately 625,000 bbl. per day (over the last seven-month period). On Dec. 9 the state production had reached a peak of over 700,000 bbl., a figure that had not been approximated since the early days of voluntary curtailment (Fig. 1). A price cut was instituted during the last half of August, but had no deterring effect on operators that were determined to take advantage of the breakdown of curtailment and produce to capacity. New reserve figures, compiled from actual potentials, available after cessation of curtailment, revealed the startling fact that California reserves were rapidly declining. This situation, coupled with the desire among operators to obtain a more equitable price for their dwindling reserves, caused a restoration in November of a portion of the August price slash. A further rise in price was effected in early December, and crude quotations at the end of the year closely approximated those in effect during the first right months. At the close of the year, the industry felt confident that the production situation was under control. In all fields where competition is keen because of close spacing, production is gradually declining. In the Los Angeles Basin especially there is no likelihood of a large amount of overproduction, unless a new pool is discovered or deeper drilling reveals a prolific source of crude. As long as the fields that are operated by a few companies, such as Kettleman Hills, North Belridge, Ventura Avenue, West Coyote, Dominguez, and some others, can be controlled, it is believed that the overproduction problem in California will be solved.

Jan 1, 1936

By T. A. Pollard, C. R. Sandberg, E. B. Elfrink

This paper presents an evaluation of compressibility factor data and a discussion of their application to the estimation of gas reserves. A correlation is presented which provides compressibility factors for use in both two-phase and single-phase hydrocarbon systems. Accuracies comparable to those obtained previously for single-phase systems only can be expected. A simple means of predicting the presence or absence of a liquid phase in a condensate system of known composition is illustrated. The correlation is based on 1,030 compressibility determinations from 21 hydrocarbon samples taken from eight oil fields. Of the data used, 75 per cent were from California, 15 per cent were from the Mid-Continent area, and 10 per cent were from South America. The average numerical deviation of the experimental data from this compressibility chart is 1.22 per cent. Charts and tables are included and discussed which illustrate the errors involved through the misuse or nonuse of compressibility factors in estimates of gas-in-place. INTRODUCTION The compressibility factor is a coefficient which expresses the deviation of a gas of given composition from the Perfect Gas Laws. A factor such as this is necessary in any calculation involving volumes of gaseous mixtures, and finds extensive application in the estimation of natural gas and condensate reserves. It is used in the decline curve, the volumetric, and the material balance methods of gas reserves estimation. The behavior of gases at high pressures has been investigated extensively in recent years and considerable data have been assembled on the compressibility characteristics of a number of gases. Notable among the investigators of high pressure gas relationships are Kvalnes and Caddya, Kay" Sage and Laceys, and Brown, Standing" and Katz4. Other contributors are Smith and Watson, Roland and Kaveler', and Stevens and Vance". The data on compressibility factors assembled by these investigators have been presented and correlated in numerous ways; particularly noteworthy is the method first presented by Kay5 which relates compressibility factor "Z" to pseudo-reduced temperature and Pseudo-reduced pressure. Other investigators have used this empirical relationship successfully and numerous charts covering a large number of gases have been constructed on this basis. It is the purpose of this paper to evaluate compressibility factor data and to illustrate the importance of their proper use in the estimation of gas-in-place for both gas and condensate reservoirs. EVALUATION OF COMPRESSIBILITY FACTOR DATA The compressibility chart presented by Standing, Katz, Brown and Holcomb in 1941 is probably the most recent and reliable chart for natural gases. The reliability of the Katz chart has been investigated by the writers for a fairly large number of gases (single-phase) in the pressure range from 500 to 10,000 psia and temperature range from 80 to 400°F. A summary of this comparison is presented in Table I. The numerical average deviation of the chart compressibility factors from the experimental compressibility factors is 1.05 per cent, and the algebraic deviation is -0.28 per cent. The Katz correlation appears to be quite accurate for single-phase hydrocarbon systems. It was based on single-phase systems and does not necessarily provide a means of accurately predicting the behavior of two-phase systems which might be encountered in condensate work. Data published recently by Sage and Oldsl' have enlarged the knowledge of phase behavior in condensate systems by covering extensively the Compressibilities of systems in the two-phase as well as single-phase regions for a wide range of temperatures, pressures and gas-oil ratios. An evaluation of these data indicates that conditions can arise, especially in condensate systems having fairly low gas-oil ratios, in which two phases occur and the usual gaseous compressibility factors do not accurately apply. The measured PVT data of Sage and Olds covering two-phase systems have been correlated with additional such data from the Mid-Continent area and South America; these are presented in Fig. 1. This chart is the result of 1,030 compressibility* determinations from 21 hydrocarbon samples taken from eight oil and condensate fields. Of the data used, 74.75 per cent were from California, 15.45 per cent were from the Mid-Continent area, and 9.80 per cent were from South America. The chart construction is based on the original

Jan 1, 1949

By C. R. Sandberg, T. A. Pollard, E. B. Elfrink

This paper presents an evaluation of compressibility factor data and a discussion of their application to the estimation of gas reserves. A correlation is presented which provides compressibility factors for use in both two-phase and single-phase hydrocarbon systems. Accuracies comparable to those obtained previously for single-phase systems only can be expected. A simple means of predicting the presence or absence of a liquid phase in a condensate system of known composition is illustrated. The correlation is based on 1,030 compressibility determinations from 21 hydrocarbon samples taken from eight oil fields. Of the data used, 75 per cent were from California, 15 per cent were from the Mid-Continent area, and 10 per cent were from South America. The average numerical deviation of the experimental data from this compressibility chart is 1.22 per cent. Charts and tables are included and discussed which illustrate the errors involved through the misuse or nonuse of compressibility factors in estimates of gas-in-place. INTRODUCTION The compressibility factor is a coefficient which expresses the deviation of a gas of given composition from the Perfect Gas Laws. A factor such as this is necessary in any calculation involving volumes of gaseous mixtures, and finds extensive application in the estimation of natural gas and condensate reserves. It is used in the decline curve, the volumetric, and the material balance methods of gas reserves estimation. The behavior of gases at high pressures has been investigated extensively in recent years and considerable data have been assembled on the compressibility characteristics of a number of gases. Notable among the investigators of high pressure gas relationships are Kvalnes and Caddya, Kay" Sage and Laceys, and Brown, Standing" and Katz4. Other contributors are Smith and Watson, Roland and Kaveler', and Stevens and Vance". The data on compressibility factors assembled by these investigators have been presented and correlated in numerous ways; particularly noteworthy is the method first presented by Kay5 which relates compressibility factor "Z" to pseudo-reduced temperature and Pseudo-reduced pressure. Other investigators have used this empirical relationship successfully and numerous charts covering a large number of gases have been constructed on this basis. It is the purpose of this paper to evaluate compressibility factor data and to illustrate the importance of their proper use in the estimation of gas-in-place for both gas and condensate reservoirs. EVALUATION OF COMPRESSIBILITY FACTOR DATA The compressibility chart presented by Standing, Katz, Brown and Holcomb in 1941 is probably the most recent and reliable chart for natural gases. The reliability of the Katz chart has been investigated by the writers for a fairly large number of gases (single-phase) in the pressure range from 500 to 10,000 psia and temperature range from 80 to 400°F. A summary of this comparison is presented in Table I. The numerical average deviation of the chart compressibility factors from the experimental compressibility factors is 1.05 per cent, and the algebraic deviation is -0.28 per cent. The Katz correlation appears to be quite accurate for single-phase hydrocarbon systems. It was based on single-phase systems and does not necessarily provide a means of accurately predicting the behavior of two-phase systems which might be encountered in condensate work. Data published recently by Sage and Oldsl' have enlarged the knowledge of phase behavior in condensate systems by covering extensively the Compressibilities of systems in the two-phase as well as single-phase regions for a wide range of temperatures, pressures and gas-oil ratios. An evaluation of these data indicates that conditions can arise, especially in condensate systems having fairly low gas-oil ratios, in which two phases occur and the usual gaseous compressibility factors do not accurately apply. The measured PVT data of Sage and Olds covering two-phase systems have been correlated with additional such data from the Mid-Continent area and South America; these are presented in Fig. 1. This chart is the result of 1,030 compressibility* determinations from 21 hydrocarbon samples taken from eight oil and condensate fields. Of the data used, 74.75 per cent were from California, 15.45 per cent were from the Mid-Continent area, and 9.80 per cent were from South America. The chart construction is based on the original

Jan 1, 1949

By Jan Law

Problems of oil recovery are attacked from the approaches dictated by the two strikingly dissimilar complexes that comprise an oil reservoir—the fluid complex and the interstitial complex. Knowledge of the fluid complex, due to labors in the fields of fluid mechanics and physical chemistry, has far outdistanced knowledge of the interstitial characteristics of the sand complex. This paper is concerned with the latter and applies the technique of statistics to petrographic facts—namely, porosity and permeability—dealing with what might be called petrometry. Statisticians have long worked within the problem of reconstruction of a universe oi variables by means of samples that comprise a small percentage of the universe from which the samples were drawn. Core-analysis data comply with the requisite of random sampling as stipulated by theoretical statistics. A basic concept of statistics employs t.he following substitution: 1. The results of sampling are arranged as a frequency distribution. 2. The observed frequency distribution is compared with a mathematically precise distribution. 3. If a sufficiently good agreement is found between the two, the precise distribution is substituted in all subsequent operations involving characteristics of the sampled material. This mathematically precise distribution is also known as the normal curve, curve of error, the probability, the Gaussian, and the bell-shaped curve and is describable with but two figures. Further, these two figures, the arithmetic average and the standard deviation, are subject to mathematical manipulation. This paper demonstrates that, in some cases in the Dominguez field of Southern California, if sufficient core-analysis samples are taken over not too great a thickness of sediments, the resultant permeability and porosity assemblages give satisfactory agreement with ilormal curves. It is shown that the indications are strong that oil wells wherein a satisfactory agreement is found are predictable as to productivity. Since the predictions are made by employing the laws of chance that are operative within sedimentation, it follows that the mechanism by which the predictions were made is a basic concept of reservoir mechanics. Therefore, tentative examples are given of the application of normal curves to the solution of problems of primary and secondary recovery. Nature of Permeability Frequency Distributions Core-analysis data are made available as a tabulated depth vs. permeability profile. The nature of the distribution of permeability values within a given strati-graphic interval may be approximated from an array constructed with samples plotted in the order of their appearance with depth (accession number) against their permeability value in millidarcys. A wide variation in the nature of the distribution of K (permeability) values for

Jan 1, 1944

By Jan Law

Problems of oil recovery are attacked from the approaches dictated by the two strikingly dissimilar complexes that comprise an oil reservoir—the fluid complex and the interstitial complex. Knowledge of the fluid complex, due to labors in the fields of fluid mechanics and physical chemistry, has far outdistanced knowledge of the interstitial characteristics of the sand complex. This paper is concerned with the latter and applies the technique of statistics to petrographic facts—namely, porosity and permeability—dealing with what might be called petrometry. Statisticians have long worked within the problem of reconstruction of a universe oi variables by means of samples that comprise a small percentage of the universe from which the samples were drawn. Core-analysis data comply with the requisite of random sampling as stipulated by theoretical statistics. A basic concept of statistics employs t.he following substitution: 1. The results of sampling are arranged as a frequency distribution. 2. The observed frequency distribution is compared with a mathematically precise distribution. 3. If a sufficiently good agreement is found between the two, the precise distribution is substituted in all subsequent operations involving characteristics of the sampled material. This mathematically precise distribution is also known as the normal curve, curve of error, the probability, the Gaussian, and the bell-shaped curve and is describable with but two figures. Further, these two figures, the arithmetic average and the standard deviation, are subject to mathematical manipulation. This paper demonstrates that, in some cases in the Dominguez field of Southern California, if sufficient core-analysis samples are taken over not too great a thickness of sediments, the resultant permeability and porosity assemblages give satisfactory agreement with ilormal curves. It is shown that the indications are strong that oil wells wherein a satisfactory agreement is found are predictable as to productivity. Since the predictions are made by employing the laws of chance that are operative within sedimentation, it follows that the mechanism by which the predictions were made is a basic concept of reservoir mechanics. Therefore, tentative examples are given of the application of normal curves to the solution of problems of primary and secondary recovery. Nature of Permeability Frequency Distributions Core-analysis data are made available as a tabulated depth vs. permeability profile. The nature of the distribution of permeability values within a given strati-graphic interval may be approximated from an array constructed with samples plotted in the order of their appearance with depth (accession number) against their permeability value in millidarcys. A wide variation in the nature of the distribution of K (permeability) values for

Jan 1, 1944

By John V. Beall

On the banks of Huzzah Creek there is a roadhouse where a group of Ozark folks were whiling away a Sunday afternoon last spring. "How about some of that 'Who Broke the Lock Off the Hen House Door,' " suggested Spinny. The old man obligingly picked up the fiddle and began the sprightly tune. His long, seamed face had ruddy cheeks and a grey stubble jaw. A thick fedora was pushed back off his scraggly hair and he wore a heavy jacket. It was 73 degrees fetchin up for 75 on that May afternoon, so naturally he sweated. The Ozark is fiddling country. The natives, to whom a half dollar looks as big as a manhole cover, put great store by fiddling, along with the other fine things of life such as fishing and horse raising. On the wooded hills, 1200 to 1700 ft above sea level, there are numerous tumbling streams with plump fish, and in clearings along the roller coaster roads are long-legged, frisky looking horses. People in the Ozarks have a reputation for self-reliance. However, they are cheery and friendly to strangers. Trespassers are very seldom shot at-except if they do something wrong or by accident.

Jan 7, 1963

By R. D. Coleman, A. E. McIlhinney, C. E. Capes

tentially valuable. These losses will probably increase with the expansion of production and will require the development of effective disposal and utilization processes under pressure of the lack of adequate disposal areas, the enforcement of air and stream pollution laws, and the economic need to obtain the maximum yield of salable product.1 Fine Coal Treatment Processes Most coal cleaning methods depend upon the density difference between coal and its impurities to effect separation. These gravity concentration methods, however, are not practical for particles finer than about 100 mesh and cleaning methods dependent upon the differences in

Jan 1, 1971

By Y. A. Chang

Phase relationships in the system Cr-Si have been established based on the melting point, X-ray, metallo-graphic, and DTA studies. The three intermediate phases, Cr3Si, Cr5Si,, and CrSi,, melt congruently at 177V ± I@,Cr3Si, 1680"i 20°, and 1490" *20°C, respectively, while the fourth intermediate phase CrSi, melts peritectically at 1413" i 5°C to Cr5Si3 and a melt containing 51 at. pct Si. The temperatures and compositions of the four eutectic isotherms occurring in this system are given below: DTA and metallographic evidences indicate that Cr5Si, undergoes a phase transformation at 1505" i20°C. The high-temperature form of this phase could not be retained by the quenching techniques used in this study. TECHNOLOGICAL interest in the developing of composite systems, consisting of Sic on the one hand as a fiber-reinforced material and metallic substances such as chromium, nickel, or Cr-Ni alloys as a binding agent on the other hand, stimulated the present investigation of phase relationships in the binary system Cr-Si. Earlier works concerning this system have been evaluated and summarized by ansen and Anderko.' Their phase diagram was based mainly on the works of Kieffer, Benesovsky, and schroth2 and Kurnakov.~ According to these authors, the three intermediate phases Cr3Si, CrSi, and CrSi, all melt congruently at approximately 1730°, 1600°, and 1550°C. However, they did not agree on the compositional stability of the fourth intermediate phase between Cr3Si and CrSi. Later Parthe, Nowotny, and schmid4 determined the structure of this phase to be tetragonal T-1 type using the single-crystal method, and concluded that this phase had a formula of Cr5Si3. Since the compilation of Hansen and Anderko,' a new phase diagram for the system Cr-Si has been proposed by Elliott5 based on the works of Goldschmidt and rand,' Guseva and ~vechkin,~ and Trusova, Kuzev, and Ormont8 and the earlier works quoted by Hansen and Anderko.' According to this proposed phase diagram, all four intermediate phases have large ranges of homogeneity and all melt congruently. More recently, Svechnikov, Kocherzhinskii, and yupkog studied the system Cr-Si by the DTA-method. According to their findings, the three intermediate phases, Cr3Si, Cr5Si3, and CrSi,, melt congruently at 1700°, 1720°, and 1475"C, respectively, while the fourth intermediate phase, CrSi, melts peritectically at 1475°C to Cr5Si3 and a melt containing 50 at. pct Si. The temperatures and compositions of the four eutectic isotherms were found to be: In view of the discrepancies existing in the literature concerning the system Cr-Si, it was decided to rein-vestigate the phase relationships in this system. EXPERIMENTAL a) Starting Materials. Chromium disilicide and chromium or silicon powders were used in the present study to prepare the melting point and DTA samples. CrSi, was obtained by directly reacting cold-pressed elemental powders in an atmosphere of Hz at a temperature of about 1250°C. Chromium powder, purchased from Stark Chemical Co., had the following impurities in ppm: Fe, 200; Mg, 1000; and 0, 250; while silicon powder, purchased from the Welded Carbide Co., had the following impurities in ppm: Ca, 700; and Fe, 3500. b) Melting-Point Determination and Differential Thermal Analysis. Cylindrical melting-point samples of approximately 13 mm in diam and 30 mm in length with a rectangular groove in the center were prepared by hot-pressing of well-mixed powder mixtures in graphite dies. Before the melting-point determination, the hot-pressed samples were ground on a sand paper to remove any minute surface contamination of graphite. A small hole of 1 mm in diam, drilled on the center portion of the samples, served as a blackbody cavity for the temperature measurements. DTA samples approximately 13 mm in diam and 15 mm in length were prepared in a manner similar to the melting-point samples. Melting points were determined using the Pirani technique under a helium atmosphere of 40 psi. The design, performance, and operation of this apparatus have been described in detail by Rudy and ~ro~ulski.'~ The temperature measurements were carried out with a calibrated disappearing-filament-type micro-pyrometer. The measured temperature was corrected for losses from the quartz window of the melting-point furnace and for deviations from blackbody conditions of the observation hole. The procedure for temperature correction has also been previously described." The DTA method of Heetderks, Rudy and Eckertl' was also used to check any phase transformations of selected alloys in the system Cr-Si. It was not possible to make remated runs on the same sample once melt-

Jan 1, 1969

By David A. Milligan

This paper outlines the research and development of a process to treat flotation tailings from the Darwin mill in lnyo County, California. A flowsheet was developed incorporating an agglomerated heap leach process using sodium cyanide to extract the silver values. Agglomeration was the key to developing this resource as the mill tailings averaged only 13% plus 100 mesh. Percolation through the heap would have been impossible without agglomeration to improve the permeability. The various tests that went into this research program are described with particular emphasis on the agglomeration techniques developed at the Anaconda Minerals Research Center. Start up and operation are discussed.

Jan 1, 1984

Jan 1, 1951

By David Cornell, D. L. Katz

Procedures for computing turbulent flow of gas in steady state near the well bore and a graphical method for predicting unsteady state laminar flow at distances from the well have been combined to compute pressure gradients in gas reservoirs. Methods are discussed for predicting single and multiple transients at constant flow rate in an infinite reservoir, predicting constant How rate. in a finite reservoir, reproducing and interpreting back pressure test data, and prediction of the behavior of a closed-in gas well. An example of the graphical method is given for a single transient and the results are compared to a published analytical solution. A typical calculation of the pressure gradient in a reservoir and the production of gas is made .starting with data from a hack pressure test. INTRODUCTION The calculation of pressure gradients throughouse a ga-reservoir at any point in its production history is a complex problem involving turbulent flow near the well bore and unsteady state flow of the gas from the reservoir. The problem is complicated further by the variety of boundary conditions that may be imposed upon the flow. Such boundary conditions include finite or infinite reservoirs. constant or variable rates of production, constant or varying bottom hole pressures, complex initial pressure distributions throughout the reservoir, and pressure maintenance through cycling. In addition to these problems there are the practical difficulties associated with natural gas reservoir analysis These might include: (1) variation. in the permeability and porosity throughout the formation. (2) variations in the thickness of the formation, (3) communication of the producing formation with other producing zones. (4) radial variations in permeability due to influx of drilling fluid. acidizing. or the buildup of liquid in the formation around the well, (5) partial penetration of the producing zone. (6) water flood, and many others. These problems will be considered eventually. In the mean- time, it is necessary to present methods of handling the case of radial flow through a homogeneous, regular, producing stratum to a single well uncomplicated by other factors. The idealized case of steady state, radial flow from a natural gas reservoir was studied by Elenbaas and Katz5 and by Mac-Koberts.' An analysis of the unsteady flow of gases through porous media has been made by Aronofsky and Jenkins' for the one dimensional laminar case with the boundary conditions of constant downstream pressure and uniform initial pressure. Solutions for the partial differential equation for unsteady state radial flow of liquids through porous media have been given by Van Everdingen and Hurst" for the constant bottom hole pressure and constant production rate cases for laminar flow in a reservoir initially at a constant pressure. The analogous heat transfer equation has been treated by Perry and Berggren9 for the case of quenching a cylindrical hole in an infinite medium to a constant temperature. The back pressure curve, which involves the variation of the bottom hole pressure as it is determined by the behavior of the reservoir as a whole. has been studied by Rawlins and Schellhardt,10 Binck-lev,' Baumel and Breitung,' and others. No complete. adequate treatment has been given for the unsteady state, radial flow of gases into a cylindrical hole from a porous medium with or without the presence of turbulent flow and for any set of boundary conditions. If one relies only on analytical solutions of the basic equations, a new solution must be obtained for each new boundary condition. Furthermore, the complexity of the mathematical expressions for boundary conditions other than the very simple cases limits the use of analytical solutions. Graphical methods exist, however. that are general in nature, accurate, and readily employed. The analysis of steady and unsteady, laminar and turbulent, radial flow for various boundary conditions with application to specific natural gas well problems by means of graphical procedures forms the content of this paper. STEADY STATE RADIAL FLOW EQUATION FOR LAMINAR AND TURBULENT FLOW A steady state radial flow equation for laminar and turbulent flow through unconsolidated sands has been given by Muskat as discussion of the work by Elenbaas and Katz.5 This equation is based on the properties of unconsolidated

Jan 1, 1953

By H. B. Huntington

Some of the basic problems in understanding elec-tromigration in metals are discussed, along with the attempts that are being made to handle them. One such problem is the effect of the electrostatic forces. It is now acknowledged that the momentum exchange with charge carriers plays generally a dominant role in the driving force but the question remains to what extent the electrostatic force may still be effective. The electromigration of interstitial impurities is also an area which presents some intriguing questions. For the substitutional impurity, moving by the vacancy mechanism under the influence of an electric field, the correlation considerations are somewhat more complex than have been previously recognized. Another problem of basic importance in the calculution from first principles is the strength of the "electron friction" force, say for a simple one-band metal. A related problem growing out of the preceding is the prediction of the direction of the "electron wind" force for metals with band structure involving both holes and electrons. THE term electromigration has come to be used to describe the flow of matter in condensed phases carrying high electronic currents such as metals and alloys, whereas one usually reserves the term electrolysis for situations where the current is largely ionic, particularly in the liquid state such as molten salts. It follows that the mass transport number in electromigration is always very small, of the order of 10-7. Studies of electromigration date back some 30 years but the modern period would appear to date from the work of Seith and Wever1 who in the mid 1950's first incorporated markers to display mass motion relative to the lattice and first suggested that the direction of the mass flow was primarily determined by the sign of the charge carriers. Since that time interest in the field has grown steadily and more rapidly recently as certain technological applications became apparent. Chief of these is certainly the deleterious effects that electromigration can cause, even at relatively low temperature, to current-carrying elements in integrated circuitry.2 These phenomena have been the subject of intense study and considerable ingenuity. On the constructive side electromigration has proved a useful tool in the purification of certain metals.3 The interest of this paper is, however, centered more on the basic aspects of the subject than on its technological applications. That high electric currents should give rise to mass flow in metals and that the driving force should be more directly associated with momentum exchange with the charge carriers than with the electrostatic field are ideas that no longer cause surprise or particular interest. The field has matured to the point where the general concepts are widely accepted and continued progress in basic understanding rests on more detailed and quantitative exploration. It is the purpose of this paper to point out what are some of the current problems. As a result, we expect to raise more questions than we answer. The first of these will be the role of electrostatic forces, if any, in electromigration. A second section will deal with the electromigration of interstitials. A third and final section treats with electromigration of substitutional impurities or of the matrix atoms themselves. ELECTROSTATIC DRIVING FORCE In the conceptual treatments of electromigration it has been customary to write the driving force in terms of an effective charge number Z* and to divide it into two terms F = e£Z* = e£[Zel- z(pd/Nd)(N/p)(m*\m*\)] [1] The first of these represents the electrostatic force under immediate consideration in this section and the second and usually dominating term for metals arises from momentum exchange with charge carriers, commonly called the "electron drag" term. As can be seen it is set proportional to the electrons per atom, z, and the ratio of the specific resistivity of the moving entity to the corresponding resistivity per matrix atom. The (m*/Im*I) factor takes into account the fact that the sign of the charge carrier determines the sign of the driving force. The specific resistivity of the moving entity is averaged over its path. In the case of motion of the matrix atoms by vacancies this gives rise to approximately one-half the resistivity at the saddle point since the scattering power of the atom at its equilibrium position bordering the vacancy differs only slightly from that of a normal matrix atom. Although the formulation of the "electron drag" term in Eq. [I] is based on a highly simplified model for electron defect scattering, the essential features implicit in the expression are common to all the theoretical approaches that have so far appeared in the literature.4-6 As for Zel, most treatments of electromigration have included the quantity as the parameter which measures the direct interaction of the electrostatic field with the ion and equated it to the nominal valence of the latter. However, there has been considerable discussion whether this interaction may not be 0 in many cases.6 If the moving ion is always enveloped by the same distribution of shielding charge, then clearly its motion will not involve any work done by the electric field and one can expect there will be no electrostatic force exerted on such a neutral composite. From this point of view the shielding charge around the ion would be said to be complete and hence the entity within the Debye shielding sphere would be unaffected by the electrostatic field per se. There is, however, the prospect that, as the moving ion progresses, new charge comes in to participate in the shielding action

Jan 1, 1970

By John Langton

In determining what kind of pourer should be adopted for the works of the Moctezuma Copper Co. at Nacozari, Sonora, Mexico, certain considerations imposed by local conditions had to be taken into account. Water.—During most of the year the water-supply is abundant for all purposes, but it dwindles rapidly when the dry season sets in, reaching a minimum flow which is entirely undergrouad. It was evident, that with the greatest care in keeping down the unavoidable loss of water in milling and smelting, these operations and hence the capacity of the works mould ultimately be limited for about two months of the year by the small watersupply available at the period of minimum flow. Transportation.—The nearest railway terminus was in Arizona, at the international boundary-line; and the price of supplies at that point would be enhanced at Nacozari by the additional cost of a 90-mile wagon-haul. During the rainy season, transport to Nacozari was much impeded, and at times made impossible, by the condition of the roads. Hence, to insure continuous operation at the works, it would be necessary to provide for hauling the year's supplies, including fuel for power and coke for smelting, in less than eleven months. In other words, the average freight delivered daily at the works should be at least 10 per cent. more than the average daily consumption. For moderate quantities of freight, pack-carriage by burros is astonishingly cheap. But it has a capacity-limit which is generally very soon reached. A 200-lb. load, and 10 miles a day, 5 with and 5 without load, is the full capacity of a burro. This means one burro per ton-mile of the round trip; and,

Jan 1, 1904

By Keith R. Bock, Norman Parlee, Albert M. Barloga

Coils of pure iron and iron-carbon alloy wire (0.05 to 0.80 pct C) and sufficient sulfur to saturate the solid phase were equilibrated in evacuated or argon filled tubes. After rapid cooling, and removal of the outside nonmetallic layer, the wires were analyzed for carbon and sulfur and the data used to construct an Fe-S binary and isotherms of the Fe-C-S ternary in the range 1149° to 1427°C. THE solid solubility of sulfur in steel is of interest in connection with such phenomena as hot shortness, burning, and so forth. "Burning," the more or less permanent damage that some steels suffer when heated for forging or rolling, has been shown to be related closely to the behavior of sulfur and less closely to carbon and oxygen.' Attempts to interpret burning phenomena in steels fail because of lack of data on the Fe-C-S and the more complex systems in this family. Rosenqvist and Dunicz 2 and Turkdogan, Ignatowicz, and pearson3 have largely elucidated the Fe-S diagram in the region of interest but no information on the Fe-C-S diagram in this region appears to be available in the literature. This paper deals with the elucidation of the Fe-C-S diagram in these interesting ranges. The method employed is different from those used by previous workers2'3 on the Fe-S system. EXPERIMENTAL METHOD Pure iron wires (Ferrovac E) or iron carbon alloy wires of 1 mm in diam were cleaned with acid and acetone, coiled, and placed in silica tubes (7 mm OD and 5 mm ID) previously closed at one end. Enough sulfur was added to assure saturation of the solid iron phase. The filled tubes were either simply evacuated and sealed, or filled with argon at a reduced pressure and sealed. The argon was required at the higher temperatures to prevent collapse of the tubes. The filled and sealed tubes were placed in the middle uniform temperature zone of a Globar tube furnace and equilibrated at temperatures ranging from 2100°F (1149°C) to 2720°F (1493°C). After equilibration the tubes were removed from the furnace and quenched in air or water, the form of quenching being found to have no effect on the results. The tubes were broken open and the coils were placed in a 1 : 1 HC1 solution to remove the sulfide-rich layer. The coils were then cut into small pieces and analyzed for sulfur and carbon. In the early stages of the investigation different equilibration times ranging up to 17 hr were tried and the cores of the wires were analyzed to test for saturation. One hour appeared to be sufficient to reach maximum sulfur content at 1454°C and 2 hr sufficient at 1149°C. The practice adopted was to use at least 3 hr at the higher temperatures and at least 5 hr at the lower temperatures. The iron-carbon alloy wires used were made by carburizing pure iron wire with carbon monoxide gas in a one inch diameter ceramic tube at about 1204°C. Differing carbon contents were obtained by allowing fairly large coils to react with the gas for varying lengths of time at a flow rate of 800 cc per min. The reacting times ranged from 15 min to 4 hr depending upon the amount of carbon desired. The furnaces used were controlled by means of Leeds and Northrup Speedomax Type H instruments with D.A.T. Control attachment. Thermocouples were calibrated against the melting points of gold and copper. The temperatures recorded appear to be accurate within i2.7OC. Starting with run No. 85 and continuing with the

Jan 1, 1962

By John L. Boardman

THE Anaconda company has never indulged in any employee activities at Butte which might be termed paternalistic, but it has exerted a vast amount of effort in care of its employees during working hours. The reason for this policy is not lack of interest or that the company does not feel the effect of employees' activities while they are "off the job"; it is that the company and the city of Butte have grown up together and each has been adequate in its own sphere, the company in providing employment at the highest possible wage and the city in providing housing, sanitation, commercial services, medical services, schools, churches, amusements and entertainments. The one exception to this independence between the company and the community is the Butte Water Co., which is a wholly owned subsidiary of the Anaconda Copper Mining Co. Mention of this relationship is made here because the water supply of such a city as Butte is one of the principal factors in determining the health of the people. Very early in the development of the Anaconda company an adequate and dependable water supply for the operations became necessary, therefore the company took over this important community function. So well has this activity worked out that during the whole period of time covered, in which the company has expanded to become practically the sole mine operator and the community has grown from a small mining camp to the status of a modern city, there has been no shortage of water or any outbreak of water-borne, epidemic disease. CONDITIONS LEADING TO ORGANIZED SAFETY EFFORT A brief sketch of conditions in Butte prior to 1912 is necessary to an understanding of the reasons for placing accident prevention on an organized basis. As early as the year 1884 there were a large number of small independent mining operations depending principally upon the production of silver, although even then copper was becoming prominent in the value of total production for the district. The Butte camp was then just emerging from the log cabin stage to that of a modern city.

Jan 1, 1938