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By Gerhard Derge

A series of studies of the corrosion of tin is under way in the Metals Research Laboratory at the Carnegie Institute of Technology. The complete program includes examination of the corrosion properties of high-purity tin and the changes produced in these properties by the addition of varying amounts of alloying elements. Other studies of this subject have been made recently under the sponsorship of the International Tin Research and Development Council, but these researches have been confined largely to the weakly acid environments commonly encountered in the canning industry.' There is little information available regarding the corrosion of tin under alkaline conditions, but such data would be of value, for a large amount of the metal is used under such conditions. The potential measurements to be described were made because they seemed to offer the most rapid method for obtaining a general view of the conditions to be encountered in such service. These experiments will also serve to establish a technique that will be of value in further studies. It must be emphasized that the results reported are those of controlled laboratory experiments and that the conclusions drawn cannot yet be applied to service conditions; rather, they point to the directions in which more exhaustive experimental work may be done to best advantage. Experimental Procedure The first work was devoted entirely to the problem of obtaining reproducible results from a series of potential measurements. Only the methods finally adopted as standard will be described here, except when the variations from these have furnished results of interest. The cell used is shown schematically in Fig. 1. The electrolyte is contained in the vessel A (an inverted bell jar), whose ground top is fitted to the transite-board lid B. The controlled atmosphere can be admitted

Jan 1, 1938

By Gerhard Derge

A series of studies of the corrosion of tin is under way in the Metals Research Laboratory at the Carnegie Institute of Technology. The complete program includes examination of the corrosion properties of high-purity tin and the changes produced in these properties by the addition of varying amounts of alloying elements. Other studies of this subject have been made recently under the sponsorship of the International Tin Research and Development Council, but these researches have been confined largely to the weakly acid environments commonly encountered in the canning industry.' There is little information available regarding the corrosion of tin under alkaline conditions, but such data would be of value, for a large amount of the metal is used under such conditions. The potential measurements to be described were made because they seemed to offer the most rapid method for obtaining a general view of the conditions to be encountered in such service. These experiments will also serve to establish a technique that will be of value in further studies. It must be emphasized that the results reported are those of controlled laboratory experiments and that the conclusions drawn cannot yet be applied to service conditions; rather, they point to the directions in which more exhaustive experimental work may be done to best advantage. Experimental Procedure The first work was devoted entirely to the problem of obtaining reproducible results from a series of potential measurements. Only the methods finally adopted as standard will be described here, except when the variations from these have furnished results of interest. The cell used is shown schematically in Fig. 1. The electrolyte is contained in the vessel A (an inverted bell jar), whose ground top is fitted to the transite-board lid B. The controlled atmosphere can be admitted

Jan 1, 1938

By H. Q. Golder

INTRODUCTION The stabilization of slopes is not a design problem. A slope is designed before it is made. For a slope to be stabilized it must already exist. The basic problem has existed for a long time. It started with cuts in soil and rock made in the 18th century during the construction of the canals which were developed at that time, and continued into the 19th century with the development of the railways, and in the 20th century with motor roads and lately open pit mining. It is not difficult to stabilize a slope, but certain questions must be asked and answered. These are: i) How much stability is required? ii) For how long is it required? iii) How important is the cost? These three questions indicate the basic problem of Civil Engineering, which is that the solution to any problem is a compromise between safety, cost and time. Stabilization of slopes is no exception. If the slope exists why is stabilization a problem? There are many possible reasons, for instance, a neighbouring and similar slope may have failed, or it may be necessary to change the conditions of the slope, steepen it, increase its height, put weight at the top, or construct a building at the foot in which case added security is required, or guarantee its stability for a longer time. MECHANISM OF FAILURE In order to pick the correct method of stabilization the mechanism of failure must be understood and the immediate cause of failure known. Often to remove the cause is the best remedy. The mechanism of failure has been studied over a period of many years in landslide problems. Pit slope failures are very similar to some types of landslides. (1) (2) (3) (4) In one sense there are many causes of landslides. Terzaghi lists 19. This means that there cannot be a standard solution to a stabilization problem. In another sense, it can be said that there is only one cause, which is gravity. This is a constant, never failing force which cannot be

Jan 1, 1971

By W. H. Hough, P. B. Leavenworth

Development in the upper Texas Gulf Coast during 1944 resulted in the discovery of 19 new fields as compared with 11 during 1943. These discoveries include 10 oil fields, one dry gas field, and eight gas-condensate fields. Drilling During the year 590 wells were drilled as compared with 418 drilled during 1943. Of these operations, 485 wells were drilled in proven fields, with the following results: 281 oil wells, 22 condensate wells, one dry gas well and 141 dry holes. The remaining 105 wells were wildcats, of which 19 were producers. The geological distribution of these discoveries was as follows: In 1944, production amounted to 178,-522,630 bbl., which was an increase of some 31,670,384 bbl. over the 1943 figure of 136,852,246 bbl. These figures include both condensate and oil production, as separate figures are not available. Wildcatting in the area was more successful during 1944 than in 1943 as the following comparison of number of wells drilled illustrates: Discoveries during 1944 Smith Point, Chambers County.—Standard Oil Company of Texas completed its No. I State, sec. 109, on Feb. 15, 1944, in a Frio sand at 8135 to 8146 ft. The well flowed 250 bbl. of 42º gravity oil through an 1/8-in, choke. Gas-oil ratio was 800 to I; tubing pressure, 1100 bbl. Four other oil wells and one gas well were completed during the year. This discovery does not appear to be of major importance. The producing area lies on the upthrown side of a large fault. North Winnie, Chambers County.—Sun Oil Co. completed No. I P. E. Dougherty on Apr. 27, 1944, from the Frio, through perforations at 8757 to 8759 ft. The initial production was 154 bbl. of 38.3º gravity oil through an 1/8-in. choke. Gas-oil ratio Was 2526 to 1; tubillg Pressure, 2280 1b.; casing Pressure, 1225 lb.; total depth, 9519 ft. Three other wells were drilled during the Year. This discovery is on the downthrown side of the major Winnie Stowell fault, and increases in magnitude the already large producing area along this fault. Mayes Field, Chambers County.—Humble Oil and Refining Company's No. I Mary Etta Mayes was completed on Dec. 24, 1944, in a Frio sand, at 8166 to 8169 ft. through 1/4-in. for 768 bbl. of 40.3º gravity

Jan 1, 1945

By W. N. Lacey, R. H. Olds, B. H. Sage

The volumetric behavior of five mixtures of black oil and natural gas and of two mixtures of condensate and natural gas from a field in the San Joaquin Valley was experimentally established. This work was carried out at roo°, I9o° and 250°F in the pressure interval between 400 and 5000 psi. The viscosity of the liquid phase of four mixtures of black oil and natural gas was experimentally measured in the above-indicated temperature and pressure intervals. The effect of methane upon the precipitation of bitumen from the black oil was studied at 230°F. Introduction The solution of a number of the economical and technological problems which arise in connection with petroleum production is dependent upon the availability of the necessary quantitative information covering the materials involved. This requires data concerning physical properties of naturally occurring hydrocarbon mixtures at the pressures and temperatures characteristic of underground petroleum reservoirs. The experimental determination of the desired data for each situation encountered is relatively time-consuming. However, it is considered to yield results sufficiently more reliable than those obtained from correlations to justify the effort. For these reasons there was undertaken a laboratory investigation of the viscosity of the liquid phase and the volu- metric and phase behavior of mixtures of oil and gas samples obtained from wells in a field located in the San Joaquin Valley. Terminology The nomenclature of petroleum engineering is not at present entirely standardized. Many commonly used technical terms are not everywhere given the same meanings. For the purposes of this paper the following definitions will be adopted: Black oil refers to the dark-colored, hydrocarbon liquid obtained when the producing horizon of the well lies partly in the condensed hydrocarbon phase of the reservoir. Condensate is the term applied to the relatively volatile, pale yellow or amber-colored hydrocarbon liquid that is often obtained from the surface separator system when the producing horizon of the well lies in the gas cap of the reservoir. The gas obtained from the surface separator system is called natural gas regardless of whether the well is producing black oil or condensate. As might be expected from the multi-component character of naturally occurring hydrocarbon materials, the compositions of black oil, condensate and natural gas are subject to considerable variation depending upon the temperatures and pressures prevailing in the surface separator system as well as upon the overall composition of the material produced from the reservoir. In order to obtain samples capable of reproducing the total hydrocarbon material produced by the well, all oil and gas mixtures used in this investigation were com-

Jan 1, 1949

By F. J. Plecity, J. T. Michalak, W. C. Leslie

Isothermal recrystallization and grain growth in zone- and vacuum-melted irons and Fe-Mn alloys, up to 0.60 pct Mn, were studied in the range 480° to 650° C, after 60 pct cold reduction. In initial stages, rate of grain growth and rate of recrystallization of iron decrease with time. The recrystallization is typical of a growth-controlled process, and rate of growth is determined by the extent of recovery. Mn decreases rates of growth and of recrystallizatzon. The recrystallization process changes at about 0.30 pct Mn and nucleation may become time-depetzdet~t. In recent years, considerable effort has been expended in determining the effects of solute elements on recrystallization and boundary migration in fcc metals. The results have indicated that the effects produced by single solute additions are dependent upon both the element added and its concentration.'-' In contrast, there have been very few attempts to determine the characteristics of recrystallization and boundary migration in high-purity bcc metals, especially after heavy deformation, and the effects thereon of single solute elements.9-11 This study was undertaken to determine the recrystallization characteristics of various "high-purity" irons and the effects of manganese additions at two levels of base purity. It was hoped that the information obtained would improve our understanding of the recrystallization of pure metals and aid in formulating a theory for the effect of solute elements. The interest was not entirely academic, for the annealing of low-carbon steels, which is of very great commercial importance, is but poorly understood. MATERIALS The compositions of the irons and iron-manganese alloys used are listed in Table I. The zone-melted iron and Fe-Mn alloys were made by Battelle Memorial Institute. Iron S-1 was arc-melted in a water-cooled steel mold in an argon atmosphere. The ingot was forged into a bar, then given two horizontal zone-refining passes in an alumina boat. Iron V-4 was treated in a similar manner, but was not zone-refined. The iron for the zone-melted Fe-Mn alloys was induction melted in vacuum in MgO crucibles and cast into alumina molds. The ingots were forged into bars, machined to shape, and a groove milled down one side of each. The best available electrolytic Mn was placed in the grooves, and the bars were zone melted. The vacuum-melted Fe-Mn alloys were induction melted in this Laboratory in MgO crucibles and poured into cast-iron molds. Iron V-5 was purchased from National Research Corp. in the form of a small vacuum-cast ingot. The low-carbon steel was made by induction melting in air at the U.S. Steel Corp. Applied Research Laboratory. The history of the materials prior to the final cold reduction differed; these details are given in the Appendix. The penultimate grain size of the principal materials was kept in the range ASTM 2 to 4, except for the low-carbon steel. PROCEDURES The cold work prior to the final recrystallization anneal was kept constant at 60 pct. It is known that rolling procedure can influence the kinetics of recrystallization of ironI2; therefore, all specimens were rolled in one direction only, between clean,

Jan 1, 1962

By Chingyuan Y. Li, C. Y. Hsieh

REALIZING that aluminum will have a great role to play in the coming industrialization of China, Chinese geologists have long been looking about for some aluminum deposits. The possible sources appear to be alunite, the alumina-rich shales, and the bauxite deposits. The locations of deposits are shown in Fig. I. ALUNITE Our attention was first directed to the alunite deposits along the southeastern coast of China. Table I summarizes the reserves now believed to exist in that region. [ ] Other alunite deposits have been found in Kiangpei, Szechuan province; Channing, Liuyang and Hsanshan, Hunnan province; Tsingchow and Chowyuan, Shantung province. No reserve figures are available. HIGH-ALUMINA SHALE Shale high enough in aluminum to serve as a source of that metal has been found in northeastern China (Table 2). [ ] In Manchuria, the Manchuria Light Metals Co., at Antung and Fushun, operating under Japanese control, has been the only active producer of aluminum. It is not known, however, whether the company uses local raw materials or imports ore from elsewhere.* SHANTUNG BAUXITE Bauxite was first recognized in China at Paoshan, Shantung province. Although the reserve is reported to be large (estimated at 271 million tons), the high content of insoluble residue (Si02) and mineral composition (diaspore) are dis-

Jan 1, 1946

ARTHUR PHILLIPS,* Bridgeport, Conn. (written discussion?).-It is to, be regretted that the very valuable paper by Messrs. Bassett and Davis did not appear in the early war period. The data presented would have been of inestimable service to inspectors, of cartridge brass who, admittedly, had little or no knowledge regarding the relation of grain size to temperature of anneal, and no real appreciation of, the significance of the Brinell hardness test. The paper is of considerable interest to, metallurgists also. WALTER R. HIBBARD, ? Bridgeport. Conn. (written discussion§).-The writer has carefully studied Messrs. Bassett and Davis's paper with considerable interest, inasmuch as our laboratory has tested cartridge brass by means of a Brinell machine. In March, 1917, at the suggestion of the Technical Department of the American Brass Co., we started a comparison of grain-size measurements and Brinell hardness of-cartridge brass with a gage of 0.1 in. or greater. This was continued until March, 1918, when we adopted the Brinell hardness test as standard for brass 0.1 in. gage or greater, and discontinued grain-size measurements upon this metal. The data collected during the test showed that the Brinell hardness indicated more accurately how the metal acted in actual working operations. It was also more reliable because two manipulators check themselves closer by the Brinell test than by the grain-size measurements. It also consumed less time in making the tests. Alfred V. de Forest, formerly assistant research engineer of our laboratories, has described the apparatus and some of the checking results in a paper read June, 1918, before the American Society for Testing Materials.1 The writer hopes that a more satisfactory. method for testing cartridge brass and gilding in gages thinner than 0.1 in. may be devised than the present method of grain-size measurements.

Jan 3, 1919

By H. A. Keller

(Chicago Meeting, being part of the International Engineering Congress, August, 1803.) Among the important implements of most of our Western lead and copper smelting-works is the slag-cart or buggy, commonly called slag-pot. A large number of such slag-pots being in service, durability, as well as lightness of running, is an important requisite, since repairs, though trifling in each single instance, may amount to a considerable item of cost in the course of a year. They should therefore be seldom necessary and inexpensive when necessary. Light run-

Jan 1, 1894

By Chingyuan Y. Li, C. Y. Hsieh

Realizing that aluminum will have a great role to play in the coming industrialization of China, Chinese geologists have long been looking about for some aluminum deposits. The possible sources appear to be alunite, the alumina-rich shales, and the bauxite deposits. The locations of deposits are shown in Fig. I. Alunite Our attention was first directed to the alunite deposits along the southeastern coast of China. Table I summarizes the reserves now believed to exist in that region. Other alunite deposits have been found in Kiangpei, Szechuan province; Charming. Liuyang and Hsanshan, Hunnan province Tsingchow and Chowyuan, Shantung province. No reserve figures are available. High-alumina Shale Shale high enough in aluminum to serve as a source of that metal has been found in northeastern China(Tab1e 2). In Manchuria, the Manchuria Light Metals Co., at Antung and Fushun, operating under Japanese control, has been the only active producer of aluminum. It is not known, however, whether the company uses local raw materials or imports ore from elsewhere.* Shantung Bauxite Bauxite was first recognized in China at Paoshan, Shantung province. Although the reserve is reported to be large (estimated at 271 million tons), the high content of insoluble residue (SiO2) and mineral composition (diaspore) are dis-

Jan 1, 1948

By Chingyuan Y. Li, C. Y. Hsieh

Realizing that aluminum will have a great role to play in the coming industrialization of China, Chinese geologists have long been looking about for some aluminum deposits. The possible sources appear to be alunite, the alumina-rich shales, and the bauxite deposits. The locations of deposits are shown in Fig. I. Alunite Our attention was first directed to the alunite deposits along the southeastern coast of China. Table I summarizes the reserves now believed to exist in that region. Other alunite deposits have been found in Kiangpei, Szechuan province; Charming. Liuyang and Hsanshan, Hunnan province Tsingchow and Chowyuan, Shantung province. No reserve figures are available. High-alumina Shale Shale high enough in aluminum to serve as a source of that metal has been found in northeastern China(Tab1e 2). In Manchuria, the Manchuria Light Metals Co., at Antung and Fushun, operating under Japanese control, has been the only active producer of aluminum. It is not known, however, whether the company uses local raw materials or imports ore from elsewhere.* Shantung Bauxite Bauxite was first recognized in China at Paoshan, Shantung province. Although the reserve is reported to be large (estimated at 271 million tons), the high content of insoluble residue (SiO2) and mineral composition (diaspore) are dis-

Jan 1, 1948

By B. Rao Pothini, Hilmar A. von Schonfeldt

One of the key elements essential to a productive and uninterrupted longwall mining operation is roof control. In several of the Island Creek Coal Company's mining sections, polyurethane has been infused 80 into strata to control severe roof failures in the face and gate entry areas. To date about 50,000 kgs (110,000 lbs) of the chemical have been consumed in a number of applications. Roof-to-floor convergence 60 and differential roof sag have been monitored to determine the need for polyurethane infusion and also to evaluate roof stability following the infusion. Stratascopic observations of the roof formed the basis 40 for confirming the need and also for estimating the required quantities of polyurethane. Both chemical infusion and roof control monitoring techniques have been applied successfully under very adverse roof 20 conditions; substantial production benefits have been realized. Operator acceptance of the system has been very good.

Jan 1, 1981

RAYMOND M. Howe (author's reply to discussion*).-Dr. Unger states that magnesite will hardly supersede dolomite in fettling after a heat; that it is hard to believe a slag composed of oxide of iron containing about 6 per cent. of phosphorus is the active corroding, agent in a boil in a furnace; and that boiling cannot be said to be the result of the chemical action of a high-phosphorus slag on a basic bottom. These are well-established facts that no one would venture to question. The authors were misinterpreted in the statement that "in the summary, it is claimed that magnesite low in lime, or of greatest purity, ranks first in resistance to slaking," etc. On the contrary, the position has been taken throughout that while a low lime content is advantageous, the presence of several per cent. of iron oxide (an impurity), is necessary in order to confer the proper bonding and sintering properties in dead-burned grain magnesite to be used for furnace hearths. We cannot subscribe to the view that pure magnesia is no better fitted for a refractory than pure lime,' nor that the pure natural varieties of magnesite; such as Grecian or Washington, must necessarily be burned with silica and oxide of iron to produce a satisfactory material. On a small scale, pure magnesia has been satisfactorily used as a refractory in the form of crucibles. In the production of dead-burned grain magnesite from the Grecian or Washington mineral, iron oxide is added but the addition of silica is neither customary nor desirable. It is possible to manufacture brick of good quality from both the Grecian and the Washington material without adding either silica or iron oxide, providing they are burned at a sufficiently high temperature. This is regularly done on a commercial scale both in America and abroad when brick of. exceptionally high refractoriness or special purity are desired. The following analysis is of an English brick of Grecian magnesite which is extremely low in all impurities.1

Jan 6, 1919

By Leon W. Dupuy

Many articles have been written describing peculiar and particular types of drilling. Little correlation has been made between the character of ground to be drilled and sampled and the type of drilling most desirable for procuring satisfactory samples. In development work, the engineer and metallurgist often desire the recovery of a sample in as physically natural a condition as possible, particularly when the sample must provide material for process tests as well as chemical and physical analyses. This paper describes the results of experimentation in drilling unconsolidated materials carrying titanium minerals in the Magnet Cove area, Ark. The drilling was most difficult in that the ground varied much in consistency, and it was vitally necessary to recover a physically natural sample. Ordinary churn drilling recovered a sample that could be analyzed chemically, but the sample was not in its natural state. The problem was successfully solved by utilizing and further developing methods used in the oil and clay industries.

Jan 1, 1949

By C. S. Samis, D. P. Seraphim

In the presence of oxygen, galena is oxidized in an aqueous medium containing ammonium acetate in accordance with the following reaction: PbS + 1/2 0, + 2 NH~Ac -» PbAc, + So + 2 NH: + H2O. This reaction was studied in an autoclave under oxygen pressure by polarographic measurement of the concentration of lead ion in solution. Oxidation rate is parabolic. The reaction products are lead acetote and elemental sulfur, the latter forming a film on the galena crystal. Reaction kinetics appear to be determined by the diffusion of lead from the galena phase to the solution interface through the film of sulfur. RECENT applications of pressure leaching on a commercial scale have emphasized the metallurgical importance of the oxidation of sulfide minerals in aqueous media by oxygen under pressure. Research experience has shown that sulfates, thio-nates, and metal oxides are the products of humid oxidation of sulfide minerals in basic solutions. The metal oxides may be solubilized in the presence of a complexing ion.' Certain oxide minerals are also amenable to treatment by this type of oxidation.' Several kinetic studies have been made of reactions of this type. Stenhouse' found that pyrite (FeS?) oxidized in a sodium hydroxide solution to produce a soluble sulfate and an insoluble layer of iron oxide and that the kinetics of the reaction were controlled by oxygen diffusion through the oxide layer. Andersen' studied the oxidation of galena (PbS) in a sodium hydroxide solution under oxygen pressure. He found the lead and sulfur to be simultaneously oxidized to produce plum bite ions and sulfate ions, and that the reaction rate was proportional to the surface area of the galena. The kinetics appeared to be determined by the reaction of oxygen and water with the galena surface. In each of the above reactions the metal and sulfur components of the mineral were oxidized simultaneously and at equal rates. In the present study the alkaline medium has been replaced by an approximately neutral solution of ammonium acetate in which lead sulfate is soluble. Under the conditions no sulfate was produced and no sulfur could be detected in the solution. The metal component of the mineral was solubilized and the liberated sulfur remained as a film of elemental sulfur on the surface of the galena crystal. A kinetic study of this reaction was undertaken to establish the kinetic mechanism and to determine the rate controlling step. Specific reaction rates were determined by oxidizing crystals of galena of measured surface areas in an autoclave maintained at the desired temperature and oxygen pressure. The rate of reaction was followed by measuring the concentration of lead in the ammonium acetate solution with a cathode ray polarograph, employing stationary platinum electrodes incorporated in the autoclave. Experimental Materials and Equipment Crystals of galena obtained from Violamac Mines, Retallack, B. C., were selected for oxidation because

Jan 1, 1957

By H. F. Webster, C. G. Dunn

Rolling md annealing procedures are described for developing the (110) preferred orientation in tantalum for use as a thermionic-emission materinl where electrodes of a uniform high work function are needed. The development of a (110) [001] annealing texture is also reported. A preferential growth process due to low (110) gas-metal surface energy is considered in explanation of the observed growth of (110) grains. ThE growth of (110)-oriented grains in thin strips of rolled zone-refined tantalum, previously discussed briefly,' is reported together with more recent information on the formation of a (110)[001.] annealing texture, i.e., one where the [001] direction of each grain lies close to the rolling direction. The development of tantalum sheet with a (110) preferred orientation (position of [001 ] directions unspecified) is of importance as a thermionic-emission material in thermionic-energy converters. Since therm ionic-emission properties of cesium-coated crystals vary over a wide range depending on (hkl) a2-7 a single (hkl) preferred orientation is more useful than either several preferred orientations or none. Furthermore, the (110) preferred orientation yields the highest thermionic-emission density for a cesium coverage of less than a monolayer.5-7 A consideration of the stability of the grain structure needed at high operating temperatures suggests that the preferred orientation itself should be produced by annealing processes. Information on annealing textures in tantalum, however, is rather limited. Pugh and Hibbard 8 obtained (111)[112] and (lll)[112] components in a 1400°C recrystallization texture in 95 pct cold-rolled foil; these components were enhanced on annealing at 2500°C. Muller9 rolled 99.97 Ta to 90 pct reduction in thickness in the final stage and noted only a slight sharpening of the rolling texture, with some intensification of the (111)[112] component upon annealing at 1200°C. The experimental procedure followed in the present work stemmed from the idea of using possible differences in (hkl) surface energies to provide a small driving force for growth of grains having the lowest (hkl) surface energy.l0* This would mean using high-purity tantalum processed into thin sheet form and annealed at high temperatures either in a noncontaminating atmosphere or in one producing additional sample purification. EXPERIMENTAL Zone-Refined Tantalum. National Research Corp. tantalum in the form of 1/8-in.-diam rod and of 99.98 purity (53 ppm 0, 15 ppm N, and 8 ppm C) was zone-melted four times. The traversing speed was 4 mm per min. Such treatment increased the resistance ratio, R293k/R20K , where R293K is the resistance of the specimen at 20°C and R20K the re-resistance at liquid-hydrogen temperature, from a value of 25 for the initial rod to 175 for the zone-refined rod (the increase in the resistance ratio provides a measure of purification11,12). Part of a zone-refined rod was rolled unidirec-tionally to a strip 0.003 in. thick and 0.28 in. wide. Samples were given anneals in the range 1300" to 2100°C using ac conduction heating in an oil-free vacuum system. Recrystallization to small grains appeared to be complete at 1300°C. Large grains were formed at higher temperatures, but these were not entirely strain-free, some grains showing asterism in Laue X-ray patterns and some displaying a range in orientation. Part of the difficulty was caused by thermal expansion of the tantalum strip as it was held between fixed supports. However, in a different arrangement with the tantalum freely suspended in a tantalum can, high-frequency induction heating in vacuo at about l0-6 Torr produced

Jan 1, 1964

By O. G. Kiel, G. W. Swift

The concept of "a continuous succession of steady-states", which has been applied successfully by Aromfsky and Jenkins to obtain a solution for the nonlinear partial differential equation describing the transient Darcy flow of gas through porous media, is demonstrated to be equally valid for transient non-Darcy flow. A mathematical model, which numerically solves the partial differential equation, is used to check the validity of the succession of steady-states solution. Comparison of sand-face pressure histories compelted by the two methods shows excellent agreement. The utility of the succession of steady-states solution in predicting performance of gas wells rests in the fact that no special computation equipment is required. The development of the succession of steady-states solution leads also to a practical method for determining and analyzing field test data. A method for taking gas-well test data under constant-rate conditions is presented. Experimental data obtained in the field by employing the constant-rate method are presented and analyzed in accordance with the succession of steady-states solution. Analysis of data in this fashion is demonstrated to give direct "in situ" information for reservoir permeability, porosity and turbulence or non-Darcy coefficient. INTRODUCTION The economics of gas production are dependent upon the transient behavior of flow within the reservoir. For production from a finite reservoir, the transient flow behavior can be subdivided into two parts. At first, the transient caused by the movement of the pressure "wave" into the reservoir is of importance. Later in the production history, the pressure-wave movement ceases and the second transient stage of material depletion becomes controlling. For reservoirs of relatively high permeability, it can be shown that the pressure wave moves into the reservoir and stabilizes quite rapidly. In the case of relatively impermeable reservoirs, quite the opposite is true. Although it is theoretically possible to compute the production capability of a well from the properties of the reservoir as determined by static tests and core analyses, more reliable information is obtained by conducting flow tests on the well and thereby obtaining some measure of "in situ" formation properties. For gas wells, there are two basic types of tests in existence: the flow-after-flow method,' and the isochronal method.' Both of these techniques are tailored to obtain data that can be analyzed in accordance with the empirical performance equation: In addition, the isochronal method makes provision for the sluggish nature of pressure-wave movement in "tight" formations by requiring pressure build-up between flows and by stipulating that data obtained on successive flows be analyzed at equal elapsed flow times. It can be demonstrated that either test is valid for reservoirs of high permeability. Further, since it has been pointed out that the pressure wave stabilizes rapidly for reservoirs of this type, tests of relatively short duration will give stabilized information on the performance of a well. Further decline of sand-face pressure and/or production rate may be determined by employing material-balance techniques. Cullender' points out that for relatively impermeable reservoirs the flow-after-flow method gives invalid results. (See Appendix C.) If the isochronal method of testing is used, there are two alternatives: (1) the tests must be conducted for a sufficient length of time to obtain stabilized information (which may require months to accomplish); or (2) some method for extrapolating the results of short-term isochronal tests must be employed. The first alternative is impracticable because of manpower, conservation and economic considerations. Recourse to the second alternative requires some assurance regarding the reliability of the extrapolation technique. Poettmann and SchilsonJ present an empirical method for predicting stabilized performance. The present investigation was originally initiated to determine the reliability of this technique. To do this, a mathematical model was developed to simulate the Darcy and non-Darcy flow of gas through porous media. The model consisted of a finite-difference approximation of the nonlinear partial differential equation which was solved on an IBM 7090 computer. Long-term production histories were simulated by the model and compared against predictions obtained from the Poettmann-Schilson method. As the work progressed, it became apparent that a straightforward predictive equation could be developed by utilizing the concept of a succession of steady-states. As a result, the emphasis of the work was redirected to exploit the advantages of the new method.

By F. W. McQuiston, L. J. Bechaud

3.2-1. Introduction. Much has appeared in the technical literature on theory of sampling (18, 37), weight of sample required in relation to particle size (28), probability of error in sampling (3), and statistical analysis of sample data (20). Each industry, whether it be copper, iron ore, or coal, has its own standards and methods. All of the rather extensive theoretical treatments appearing in published literature on sampling apply to material already on hand such as coal, iron ore, or copper concentrates in rail cars, or in moving streams such as on conveyor belts. The attempt usually is to apply statistical techniques in order to improve reliability and precision in sampling, and to reduce differences between the analyses of seller and buyer. In contrast to this type of sampling, very little has appeared in the literature on sampling a virgin deposit from the metallurgical point of view. Perhaps it would he more descriptive to designate this point of view as "Gm-metallurgical," since geology is inextricably interwoven with metallurgy in gaining an understanding of the complexities of a deposit, eventually leading to a definition of mineable reserves, with the development of a flowsheet and engineering criteria for the planning of a successful and profitable operation. The degree of cooperation between these two departments often determines whether the processing plant is a success at the inception of operations, or whether expensive changes and modifications must he made, with the plant finally reaching rated capacity at some later date. The first concern of the metallurgical department should be to establish proper accreditation of the samples which will be used in any ore-testing campaign. It should he made mandatory, as part of operating management policy, for the responsible metallurgist to he aware of the significance of the samples and to become intimately knowledgeable in all aspects of metallurgical behavior and response to treatment of all varieties of ore in the deposit under consideration.

Jan 1, 1968

By ALEXANDER L Hay, Alexander L.

THE Sydney coal field, the largest and most valuable in Nova Scotia, is on the northeastern coast of the Island of Cape Breton, extending from Mira Bay on the south to Cape Dauphin on the north, a distance of 30 miles, and has a general dip northeast under the sea. The field embraces the mining villages of Morien, Birch- grove and Reserve and the towns of Dominion, Glace Bay, Waterford and Sydney Mines. The city of Sydney is about midway between the northern and southern extremities of the field and on the western fringe of the productive coal measures. Sydney harbor crosses the coal field, cutting off direct rail connection between Sydney Mines and the greater part of the field to the southeast.

Jan 1, 1928

By Kennedy, Joseph E.

MANY things must be considered in coming to a decision as to what type of crushing and grinding equipment is to be used for preparing run-of-mine ore for concentration, amalgamation, flotation, or cyanidation. This paper is intended in no sense as a thorough discussion of these various factors, but rather contains a few observations based on a wide experience in the manufacture and application of milling machinery. One important governing factor is the tonnage to be dealt with. In large plants treating several thousands of tons in eight hours, a large jaw or gyratory crusher of substantial construction is standard equipment for reducing ore to 8 or 10 in. or finer. In open-pit work, using power shovels with 4- or 5-yd. dippers, a jaw crusher should have a receiving opening of 48 by 60 in., or 60 by 84 in., so that dynamite or hand sledging will not be required for breaking to a finer size before primary crushing. The coarsely broken ore is then conveyed by a belt to vibrating screens, the oversize from which is again conveyed by belts to secondary crushers having openings of 12 or 14 in., the product from which is conveyed to storage. From storage, the material goes to a finishing gyratory for reduction to 1/4 in. or finer.

Jan 1, 1936