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By Reuben B. Ellestad, Fremont F. Clarke

Lithium chemical plant extraction methods are discussed with reference to 1) base exchange with alkali sulphates; 2) processing based on roasting with lime; 3) miscellaneous methods; and 4) application of the Lithium Corp. process to extraction of lithium from run-of-mine, low grade spodumene ore, or concentrates. IN the early days of the lithium industry most of the production was from lepidolite, zinnwaldite, and amblygonite. Nearly all the early extraction processes described in the literature involve heating the finely ground mineral with sulphuric or hydrochloric acid. On subsequent water leaching most of the bases present in the mineral (especially aluminum) are dissolved as sulphates. As a result, the leach solution required extensive chemical purification before the lithium could be precipitated as carbonate. Following the remarkable growth of the lithium industry to its present size, zinnwaldite and amblygonite ores must be considered of minor importance only. Attention is now focused on spodumene, abundant enough in North America to be a major source of supply, and there are important supplies of lepidolite and petalite in Africa. The extraction processes described below all apply to spodumene, although several will also operate on other lithium minerals, such as petalite. Base Exchange with Alkali Sulphates: A distinct advance was made with the disclosures of Wadman and von Girsewalt. In these methods the finely ground silicate ore (spodumene or lepidolite) is intimately mixed with an excess of alkali sulphate (usually K2SO4) in at least a 1 to 1 proportion, and the mixture was heated to a relatively high temperature. Base exchange results, with the formation of lithium sulphate. A water leach dissolves the lithium sulphate, together with the excess potassium sulphate. Successful operation of this type of process requires very thorough grinding and mixing, as well as careful temperature control. The use of K2SO4 is objectionable from cost considerations since purification of lithium carbonate requires the use of potassium carbonate, if the K2SO4 is to be recovered and recycled. The lower solubility of K2SO4 as compared with Na2S04 is also objectionable, since it limits the concentration of the Li2SO4 solution to be precipitated by K2SO4. Early laboratory-scale investigation of this process by Lithium Corp. was not encouraging. Other related base exchange processes are those of Lindblad, Wallden, and Sivander3 and Sivander, Gard, Villestad, and Wallen4. The former covers the reaction of lithium silicate minerals with a sodium sulphate solution, at 100" to 300°C (under pressure), while the latter involves the extraction of silicate minerals with molten sodium sulphate. Both these processes would seem to be difficult and expensive to operate.

Jan 1, 1956

By Dwain K. Butler

INTRODUCTION Characterization of a site for the prediction and simulation of dynamic events requires the determination of mechanical properties of the rock at stress/strain levels and rates and at a scale appropriate for the events and critical structures involved. The structures of interest can be on the surface, underground, or designed to impact and penetrate into the site (projectiles). Dynamic events of interest are equally diverse: seismic waves from distance earthquakes or explosions; close-in phenomena associated with earthquakes and explosions; vibrations associated with heavy equipment or machinery; and stress transients associated with impact and penetration. The complexity of site characterization depends on two factors not specifically related to the nature of the site itself: the stress levels generated by the dynamic event and the sophistication of the prediction and simulation techniques. For very high stress levels, such as occur near a nuclear detonation, and for low stress levels, such as occur during seismic wave propagation, site characterization is simplified, and often certain details of the site are not particularly important, such as shear strength variations in the case of very high stress levels. In the intermediate stress range, however, all descriptive relations are non- linear, a complete finite strain constitutive model is required, and all details of the site, such as lithology and fracture distribution, become important. The site characterization must be complete enough to support the most sophisticated prediction and simulation technique that will be applied to the analysis of the dynamic event. The procedures of site characterization are illustrated in this paper by a specific dynamic event, projectile impact and penetration, and a specific site, an outcrop of Dakota Sandstone near San Ysidro, New Mexico. The structure of interest was the projectile itself: nominally, 1.5 m in length, 0.165 m in diameter, 180 kg

Jan 1, 1984

By V. N. Cox, C. H. Grant

Both the underwater method and the rock cratering method contribute useful information in evaluating and comparing new explosive compositions. Results indicate that metallized explosive systems which contain no high explosives can be formulated to offer more energy and to do potentially more work than other slurry explosive systems. Commercial field trials are presently being conducted with a metallized explosive that does not contain any high explosive. Although there have been only a few commercial blasts to date, the results are encouraging. The Dow Chemical Co. has been engaged in explosives research since 1953. The incentive for this research was based on the desire to find additional markets and uses for magnesium metal of which DOW is a heavy producer. The thermodynamic calculations for explosives incorporating light metals indicate energies approximately twice that of nonmetallized explosives currently being used. Early in 1960, additional patent rights were acquired from independent inventors and a development station at Virginia, Minn., was set up to conduct a commercial testing and market evaluation program with this new product. The actual manufacturing of the explosive was to take place in the boreholes. Due to the complexities involved in controlling the manufacture of the explosive in the borehole, performance was sometimes in doubt. Furthermore, experience indicated that the metallized explosive systems could not be evaluated by the standard laboratory methods then being used, and it was necessary for us to look for more suitable research methods. Tests were conducted on several known methods for explosive evaluation. The most promising were the Navy underwater method for energy evaluation and a modified Livingston crater method intended to compare explosive performance in rock. After shooting over 2000 charges of 8 to 60 lb under water and in taconites and granites with many types of explosives, a metallized explosive was developed which is now being manufactured at a pilot plant in Virginia, Minn. and is being evaluated commercially. UNDERWATER METHOD An underwater method of evaluating explosives has a number of advantages. A permanent site can be established and operated indefinitely. A large number of charges may be fired in a short length of time. The medium in which the explosive is shot is exactly the same for successive shots. Data are recorded electronically minimizing human judgment. A disadvantage of the underwater method is the lack of confinement provided by the water medium. Many explosive compositions require a greater degree of confinement to develop good energy release. Although the relative significance of the two components of energy release that are usually measured, the shock energy and the bubble energy, and their relationship to breaking rock are not clearly understood, the underwater method is a valuable research tool for screening explosive compositions and gaining an insight into the manner in which explosives release their energy. Fig. 1 shows schematically the underwater apparatus. The piezoelectric gages are calibrated tourmaline crystals which convert the shock wave to an electrical impulse which is transmitted to an oscilloscope and recorded on Polaroid film. The shock traces are picked up by scopes 1 and 2. Scope 1 is timed to pick up the full trace whereas scope 2 is timed to cover the first increment of the shock trace expanded, and therefore allows full inspection of the propagation and peak pressures. Scope 3 records the bubble trace. When the explosion occurs, a bubble of gaseous detonation products is formed. The outward momentum of the water keeps expanding the bubble even after

Jan 1, 1963

By R. A. Harrington, H. R. Nelson

The: structure of anodic films formed on aluminum and other metals under varied conditions is not well known despite the wide use of such films both as protective coatings and as the dielectric medium in electrolytic condensers. The present work was undertaken as a survey of the possibilities of electron diffraction in the investigation of anodic films, especially in comparing the properties of anodic films formed under different sets of conditions and subjected to various subsequent treatments. In addition, an effort has been made to compare surface films formed on aluminum by anodic treatment with surface films formed by heating, immersion in chemicals, etc. The elcctron diffraction method in many cases has been successfully applied to the study of thin surface films. Its principal advantage is that it can be used without removing the films from the base material upon which they have been formed. The low penetrating power of electrons, in the "reflection" diffraction method which has been used in this work, prevents the appearance of diffraction patterns from substances at depths greater than about 100 Angstrom units (lop6 cm.). Different investigations of the structure of anodic films have showll widely varying results, depending on the methods used in preparing the films. Apparently under some conditions these films are crystalline and under other conditions they are amorphous, and it has been difficult to say which type of structure will be found in any particular case. Schmid and Wassermann's1 X-ray diffraction patterns of eloxal‡ films show two broad, diffuse bands, which these investigators attribute to finely divided cubic y-Al2O3.§ Burgers, Claassen, and Zernicke³ obtained sharp X-ray

Jan 1, 1940

By R. A. Harrington, H. R. Nelson

The: structure of anodic films formed on aluminum and other metals under varied conditions is not well known despite the wide use of such films both as protective coatings and as the dielectric medium in electrolytic condensers. The present work was undertaken as a survey of the possibilities of electron diffraction in the investigation of anodic films, especially in comparing the properties of anodic films formed under different sets of conditions and subjected to various subsequent treatments. In addition, an effort has been made to compare surface films formed on aluminum by anodic treatment with surface films formed by heating, immersion in chemicals, etc. The elcctron diffraction method in many cases has been successfully applied to the study of thin surface films. Its principal advantage is that it can be used without removing the films from the base material upon which they have been formed. The low penetrating power of electrons, in the "reflection" diffraction method which has been used in this work, prevents the appearance of diffraction patterns from substances at depths greater than about 100 Angstrom units (lop6 cm.). Different investigations of the structure of anodic films have showll widely varying results, depending on the methods used in preparing the films. Apparently under some conditions these films are crystalline and under other conditions they are amorphous, and it has been difficult to say which type of structure will be found in any particular case. Schmid and Wassermann's1 X-ray diffraction patterns of eloxal‡ films show two broad, diffuse bands, which these investigators attribute to finely divided cubic y-Al2O3.§ Burgers, Claassen, and Zernicke³ obtained sharp X-ray

Jan 1, 1940

By A. B. Cook

Gas cycling is generally considered a much less efficient oil recovery mechanism than water flooding. HOWever, recoveries from some fields have been exceptionally high as a result of gas cycling. Recovery from the Pick-ton field, for example, was calculated to be 73.5 perceni of the stock-tank oil originally in place. In evaluating pressure maintenance projects, determining how much of the recovery is due to displacement by gas and determining how much is due to vaporization of the imrnohile oil in the flow path of the cycled gas is very difficrilt. Even though most of the oil is recovered by displacetr~ent, the success of a project may depend on the amount of oil vaporized. A limited number of experiments have heen performed with a rotating model oil reservoir that simulates gas cycling operations and allows a separation of the oil from, tile free gas flowing into the laboratory wellbore at reservoir conditions, thus revealing which is displaced oil and which is vaporized oil. It Iras been determined that the amount of varporizatio'n is .significant if proper conditions exist These experiments show that oil vaporization depends on pressure, temperature, volatility of the oil and amount of gas cycled. Increases in each of these conditions increase the volume of oil vaporized. Data from six experiments affecting vaporization are presented to illustrate reservoir condition that range from favorable to unfavorable. 111 these eaperitnenis recovery by vaporization ranged from 73.6 to 15.3 percent of /he immobile oil (oil not produced by gas displacerrlt). INTRODUCTION Between 1930 and 1950, gas cycling was a popular. oil recovery practice. especially for the deeper reservoirs. Later, with many case history-type studies published for both gas cycling and waterflooding, it was generally believed that waterflooding was far superior to gas cycling, even when gas cycling was conducted as a primary production procedure by complete pressure maintenance. A good example illustrating the advantage of water-flooding over gas cycling is given in a paper by Matthews' on the South Burbank unit where gas injection was followed by waterflooding. The author concluded in part that "Early application of water injection, without the intervening period of gas injection, would have recovered as much total oil as ultimately will be recovered by waterflooding following the gas injection, and total operating life would have been shortened". This appears to be a logical conclusion. However, it should not be applied to all fields. Pressure maintenance with gas in the Pickton field, as reported by McGraw and Lohec;' will result in a much larger percentage of oil recovery than was obtained in the South Burbank unit. The great success in the Pickton field resulted partly from vaporization of the immobile oil in the flow path of the cycled gas. The amount of vaporization is related to the following conditions: volatility of the oil as reflected by the APT gravity of the stock-tank oil; reservoir temperature; reservoir pressure during gas cycling; and the amount of gas cycled. Therefore, the U. S. Bureau of Mines is investigating these effects on vaporization in a research project using a model oil reservoir. Three different stock-tank oils having 22, 35 and 45" API gravities are being used as base stock to synthesize reservoir oils. Experiments are being performcd to determine vaporization at 100, 175 and 250F and at 1,100, 2,600 and 4,100 psia. This is a progress report showing the results from six experiments. Other Bureau of Mines reports"- concerning vaporization are listed. LABORATORY EQUIPMENT AND PROCEDURES The equipment ' consists of an internally chromium-plated steel tube packed with finely sifted Wilcox sand. The tube is approximately 44 in. long and has an ID of 13/4 in. The sand section contains approximately 570 ml of voids, has a porosity of 32 percent, and a permeability to air of 4.3 darcies. A unique feature of the laboratory reservoir (Fig. 1) permits the tube part to rotate at 1 rpm while the outlet and inlet heads are held stationary. The outlet end contains diametrically opposed windows to permit observatlon of the flowing fluids, and two valves, one on the top and the other at the bottom. Oil and free gas. when being produced simultaneously, can be separated by manipulating the two valves to keep a gas-oil interface in view through the windows. Thus, only gas is produced through the top valve and only oil flows through the bottom valve. The laboratory equipment was designed to study vaporization. Therefore, a uniform reservoir was made using dry sifted sand as opposcd to using a consolidated sand core with interstitial water. Furthermore. the reservoir was tilted to minimize fingering of gas. This tilting also in-

By G. D. Cremer, J. J. Cordiano

Aluminum powder is a well-known article of commerce and in various forms has been marketed widely for use in paint, for pyrotechnic purposes and for exothermic mixtures. For a number of reasons, however, aluminum powder has not been employed extensively in powder metallurgy, although a great many proposals along this line have been offered. Aluminum and alumiuum-alloy powders oxidize readily upon exposure to air and the thin film of oxide (or hydroxide) thus formed is highly refractory, in that ordinary gaseous reducing agents such as hydrogen or carbon monoxide do not reduce the oxide to metal at temperatures below the melting point of aluminum. It has been thought that the presence of these films of oxide on aluminum particles would interfere markedly in powder metallurgical work and a number of suggestions have been made, either for preventing the formation of the film through the production of the powders in inert or reducing atmospheres, or for the removal of the oxide by means of powerful reducing agents, including "nascent" or atomic hydrogen released from metal hydrides. A second and more serious difficulty in the use of aluminum and aluminum-alloy powders in powder metallurgy resides in the fact that during compression such powders tend to adhere or cold-weld to the die walls, thus interfering with the formation and ejection of a compact. A third difficulty, which has been encountered only with aluminum-alloy powders, is their hardness when compared with elemental aluminum. Certain of these powders are susceptible to age-hardening, which further hinders the formation of strong green compacts. These conditions are particularly true of atomized aluminum-alloy powders. Even in the annealed condition, plastic deformation of alloy powders under pressure is low when compared with unalloyed powders. This fact, coupled with the lower corrosion resistance of the alloy powders. is probably the significant factor in our failure to obtain strong sintered pieces. Methods of Puoducing the Powder Many methods have been proposed for manufacture of aluminum powder, only a few of which are used commercially. Several of the more important processes include: (I) atomization of the molten metal; (2) mechanical pulverization and other types of comminution; and (3) graining, in which molten aluminum is stirred during freezing. For pigment and certain pyrotechnic uses aluminum flake powder is desirable, because of its greater proportion of surface to volume; and large quantities of such material are made by a procedure that involves stamping or ball milling. In making flake intended for use as pigment,

Jan 1, 1943

By G. D. Cremer, J. J. Cordiano

Aluminum powder is a well-known article of commerce and in various forms has been marketed widely for use in paint, for pyrotechnic purposes and for exothermic mixtures. For a number of reasons, however, aluminum powder has not been employed extensively in powder metallurgy, although a great many proposals along this line have been offered. Aluminum and alumiuum-alloy powders oxidize readily upon exposure to air and the thin film of oxide (or hydroxide) thus formed is highly refractory, in that ordinary gaseous reducing agents such as hydrogen or carbon monoxide do not reduce the oxide to metal at temperatures below the melting point of aluminum. It has been thought that the presence of these films of oxide on aluminum particles would interfere markedly in powder metallurgical work and a number of suggestions have been made, either for preventing the formation of the film through the production of the powders in inert or reducing atmospheres, or for the removal of the oxide by means of powerful reducing agents, including "nascent" or atomic hydrogen released from metal hydrides. A second and more serious difficulty in the use of aluminum and aluminum-alloy powders in powder metallurgy resides in the fact that during compression such powders tend to adhere or cold-weld to the die walls, thus interfering with the formation and ejection of a compact. A third difficulty, which has been encountered only with aluminum-alloy powders, is their hardness when compared with elemental aluminum. Certain of these powders are susceptible to age-hardening, which further hinders the formation of strong green compacts. These conditions are particularly true of atomized aluminum-alloy powders. Even in the annealed condition, plastic deformation of alloy powders under pressure is low when compared with unalloyed powders. This fact, coupled with the lower corrosion resistance of the alloy powders. is probably the significant factor in our failure to obtain strong sintered pieces. Methods of Puoducing the Powder Many methods have been proposed for manufacture of aluminum powder, only a few of which are used commercially. Several of the more important processes include: (I) atomization of the molten metal; (2) mechanical pulverization and other types of comminution; and (3) graining, in which molten aluminum is stirred during freezing. For pigment and certain pyrotechnic uses aluminum flake powder is desirable, because of its greater proportion of surface to volume; and large quantities of such material are made by a procedure that involves stamping or ball milling. In making flake intended for use as pigment,

Jan 1, 1943

By Arthur Notman

(San Francisco Meeting, September, 1915) SACRAMENTO HILL is a mass of granite porphyry intruded along a fault between Paleozoic sediments and pre-Cambrian schists in the Bisbee district, Cochise County, Arizona. The intrusion invaded both walls of the fault to a large extent, and the accompanying extensive mineralization of the Paleozoic limestones is the locus of the great high-grade copper orebodies of the Bisbee mines. Prior to 1909, although the presence of ore in the mass of the hill itself had long been suspected, systematic exploration had not been attempted. A few shallow pits on the surface here and there had disclosed some chalcocite with associated carbonates as stringers in a mass of strongly brecciated, silicified, and iron-stained porphyry. The workings in the surrounding limestones had penetrated the porphyry in a dozen or so places for some distance from the contact but had disclosed no ore. However, the rock had been largely altered to quartz and sericite and very thoroughly impregnated with pyrite and traces of the copper sulphides. A close geological study of the conditions, both surface and underground, strengthened these suspicions, and plans for prospecting the hill were made in 1909. Reference to the accompanying illustrations, Figs. 1 and 2, will give an idea of the general appearance of the surface. The mineralization is more intense in two main zones, one at the west end and the other at the east end of the hill. The outcrop of the hill is elliptical and approximately 3,000 ft. long by 1,400 ft. wide. The Sacramento shaft, which is the main hoisting shaft of the mine and situated at the east end of the hill, as shown by the accompanying map (Fig. 3), offered a convenient base for prospecting that end of the hill, while the workings from the Holbrook shaft offered a similar opportunity at the west end. The choice of level for the first work was determined by analogy with the most favorable depth for enrichment below surface observed in the other disseminated deposits of the Southwest.

Jan 8, 1915

By H. A. Wriedt

At 500°C (932°F) the range of y' iron nitride is from 5. 77 + 0.03 wt pct N (in coexistence with a iron) to 5.88 * 0.03 wt pct N (in coexistence with E iron nitride). Stoichiometric "Fe,N" (5.900 wt pct N) is near the upper extreme of possible compositiom. The depe-dence of nitrogen activity (expressed as pnh,/Ph,) on nitrogen content is described satisfactorily by a "Langmuir" isotherm: At even the highest nitrogen concentrations, less than 0.18 pct of' the nitrogen atoms present are impositions of disorder. Past investigations1-4 of the Fe-N system have left only details of the thermodynamic behavior of the y' nitride, "Fe,N9', to be studied. The present investigation was made to establish more precisely than hitherto the limits of composition and the relation between composition and nitrogen activity at 500°C. EXPERIMENTAL TECHNIQUE The compositions of nitrides in equilibrium with various NH, + Hz mixtures at 500°C were determined from the weights gained by 0.02-in.-thick (4.0 to 4.5 g) strips of purified iron* when the nitrides were formed A description of the gas generation and furnace system has been published.5 Cracking and blistering during conversion of the original solid iron at 550°C injected considerable porosity into the strips without causing their disintegration. The time for complete conversion was significantly lowered by periodically reducing partly nitrided specimens in hydrogen and then reexposing them to the nitriding gas. Gas mixtures producing single-phase were used in the equilibrations at 500°C. Equilibrium was regarded as existing when the specimen weight was not detect-ably affected by further exposure to the same conditions. The gas compositions and nitrogen activities at which y' transformed to a iron (lower activity limit) and to E iron nitride (upper activity limit) were redetermined during the investigation. A specimen was equilibrated in an NH, + Hz mixture at 500°C and then exposed to a s1ightly different gas. When equi- librium had been reestablished the gas was again changed slightly. At each stage of this repeated process, while the specimen was reacting with the gas, the variation of its weight with time was observed. The onset of phase transition was marked by an abrupt change in the amount and rate of weight gain or loss. The specimens were weighed outside the furnace, in air and at room temperature, on a balance with 0.05 mg precision. When it was found that the specimens were oxidizing at a significant rate during the weighing, a series of timed weighings was made with each specimen, starting 1 min after its exposure to air. RESULTS AND ANALYSIS The gain in specimen weight from oxidation during weighing was linear in the logarithm of time between 1 min and about 2 hr, Fig. 1, later becoming linear in the cube root of time. In the logarithmic period, nitride specimens oxidized two to three times as fast as

Jan 1, 1970

By F. S. Sinnatt

THIS paper is the outcome of an extended investigation carried out in association with Dr. L. Slater. The inquiry had been continued in various directions and a number of results are quoted from an investigation recently completed by S. H. Jenkins. In projecting the work some five years ago, the author had in view a general attack on the problem of the spontaneous combustion of coal from an angle that had received little attention. The basic idea was to obtain a "slow motion study" of the active combustion of coal. This included an examination of the conditions prevailing in a mass of coal at the moment when active combustion ceases. It was thought that, if the factors governing the extinction of combustion in coal could be definitely established, it might offer an explanation of the manner in which the spontaneous combustion of coal originates. The inquiry arose from a detailed study of the properties of fusain that the author began in 1918. Fusain seemed to possess characteristics quite distinct from the coal with which it was associated, for if it were collected into a heap and one portion were heated by a small flame the combustion would traverse the whole mass. This combustion was not accompanied by smoke and passed slowly through the heap of material. Later, it was found that coals, including anthracites, would behave in a similar manner provided they were in the form of powder and that the particles were smaller than a certain size. The limiting size of particles is a definite characteristic of the coals investigated. In view of the fact that fusain exists with coal in a state that enables it to undergo this particular form of combustion, it must be assumed, sometimes, to playa definite part in the spontaneous combustion of coal in the goaf (waste).

Jan 3, 1925

By P. H. Dudley

When we see the magnificent passenger-trains of from 8 to 12 coaches, drawn by locomotives weighing from 100 to 110 tons, at speeds of from 50 to 60 miles per hour between terminals, to make a schedule of 45 miles per hour, and freighttrains of from 50 to 75 cars of 60,000 pounds capacity, drawn by one locomotive, it is hard to realize that it lacks a few months of fifteen years since my pioneer 5-inch 80-pound rail for the United States was laid by the New York Central aid Hudson River Railroad Co., in July, 1884, on the Harlem line. Shorter passenger-trains, of from 4 to 5 coaches, are run much faster, notably the Empire State Express, the schedule of which for the 440 miles between New York and Buffalo requires 53.3 miles per hour, calling for a running-speed, for much of the time, of from 65 to 75 miles per hour, while higher speeds are very common. On other railroads laid with my 5 1/8-inch 80-pound rail, speeds of from 60 to 75 miles per hour obtain in daily practice. On many of the important railroads east of the Mississippi high speeds of from 60 to 70 miles per hour are part of the daily service. So many instances of speeds of 90, and even 100, miles per hour have been recorded that they must be considered as likely to occur on important lines, and provision must be made for them in the track. Solid mail-trains of from 6 to 8 cars are run from New York to Chicago, 1000 miles, in twenty-four hours; and, commeneing with the present year, shorter trains are running from Chicago to San Francisco, 2000 miles, in three and one-half days. In the freight-service equally important progress has been

Jan 1, 1900

By A. W. Furbank

IN reviewing the aerial cameras produced in different countries, it becomes apparent that in nearly all of them an attempt has been made to secure the greatest possible angle of view. This angle, of course, is determined by the objective. The objectives most commonly in use in aerial cameras have a maximum angle of 65º. The objective developed for this new Zeiss camera combines freedom from distortion and brilliant definition, with an angle of 95º. Aerial mapping, it is claimed, has been placed on a different economic basis, and new possibilities presented, particularly in connection with automatic stereoscopic plotting instruments, to which some short references are made. One way of enlarging the angle of view is to couple several instruments with their axes convergent, thereby producing a multilens camera. Typical of cameras of this sort in the United States is the Bagley four-lens camera, which later was developed into the five-lens camera (T3-A) of the U. S. Air Corps. More recently, in order to get away from the unfavorable Maltese cross image field of the five-lens camera, and to obtain a more practical form, two five-lens cameras were combined. By using them in tandem and rotating them by 45º relatively to each other, a ten-lens camera was produced, covering an octagonal ground area, with a total angle of view of 140º. Similar designs have been evolved in other countries. In all of them, however, a number of difficulties have arisen, quite apart from their large weight and high cost. Because of their complex mechanism, numerous shutters and magazines, and the high precision with which these parts must be interadjusted and synchronized, these cameras are far from dependable Moreover, a multilens camera by itself does not yet constitute a complete outfit for producing pictures suitable for photogrammetric survey. Because all the component pictures, except the central one, are obliques, it is always necessary to employ rectifying apparatus which transforms the marginal views to the perspective of the central one. In multilens cameras with many individual magazines, it is not convenient to

Jan 1, 1938

By C. S. Brooks

Several of the commonly used methods for deter-mination of effective grain densities of minerals have been evaluated for accuracy and precision, and their applicability to various types of petroleum reservoir minerals tested. Consideration was given to the effect of consolidation, swelling clay, and wettability on these grain-density determinations. Procedures with helium displacement, a modified low-pressure Boyle's law porosimeter, and liquid displacement (water, n-decane, and n-octanol) were tested. The helium-displacement procedure was used primarily as an independent reference for which the effects of fluid-solid interaction, e.g., adsorption and wettability, were negligible. The procedures with the Boyle's law porosimeter and with liquid displacement are the methods in common use. Minerals investigated included calcite, West Texas limestone core samples, California sandstone core samples, and Wyoming bentonite. The number of samples tested, while not large, was adequate to permit application of statistical methods. Grain-density measurements on calcite (Iceland spar) provided a basis of comparison for the accuracy and precision of the procedures under investigation for a material with a high degree of chemical and physical homogeneity and for which fluid-solid interactions were at a minimum. Liquid-displacement procedures (water or n-decane) provided the greatest reliability and precision for measurement of the grain densities of the limestone tested. Gas-displacement procedures (helium or Boyle's law porosimeter) provided the greatest reliability and experimental convenience, if not the greatest precision, for the measurement of the grain densities of the swell- ing clay, Wyoming bentonite, and the shah sandstones which -contained appreciable amounts of swelling, in-terstitial clays. These experiments were designed to evaluate the applicability of the grain-density procedures in common we to some of the less tractable minerals—tight limestones, shaly sandstones, and swelling clays. The results should provide a useful basis for a selection of the method most suitable for application to the various petroleum reservoir minerals encountered and especially for use in the estimation of formation porosity. INTRODUCTION These experiments were undertaken to evaluate the accuracy and precision of several commonly used methods for determination of effective grain densities of minerals, and to test their applicability to various types of petroleum reservoir minerals. Consideration was also given to the effect of consolidation, clay, and wettability on these grain-density determinations. Procedures used included measurements with helium displacement, with a modified low-pressure Boyle's law porosimeter, and with liquid displacement (water, n-decane, and n-octanol). The minerals investigated included calcite, West Texas limestone core samples, California sandstone core samples, and Wyoming bentonite. The accurate determination of the porosity of petroleum reservoir formations, in particular those of low porosity, has received much attention. Both bulk-volume and grain-volume measurements necessary in the evaluation of porosity have been examined by many investigators with the objectives of improving both the accuracy and the precision of these determinations. In this investigation statistical criteria for selection of the most reliable and suitable procedure for use with a given type of mineral are demonstrated. The grain-volume measurement procedures appear to be the most susceptible to improvement.

Jan 1, 1958

By John C. McDonald

The amount of published literature in the field of mechanical properties of magnesium alloys is not great; particularly with respect to rolled alloys. Haughton and Prytherchl have summarized most of the articles to 1937, including their own work on sheet. Although many papers can be found dealing with the technology of magnesium and the alloys now in commercial use, there does not seem to be any work dealing exclusively with the variation in properties of rolled alloys as caused by changes in alloy composition. Comparison of published data reveals considerable discrepancies in properties of alloys of the same composition, probably due to differences in the details of working and heat-treating followed by different workers. The purpose of this paper is to study the properties of alloys in conditions where the effects of such differences have been eliminated. It is well known that the strength and ductility of metals are functions of the working and heat-treating they have received, as well as of their chemical composition. In comparing alloys with respect to these properties, therefore, all possible combinations of the variables of the fabrication procedure ought to be carried out on each alloy. One or more of these treatments mill produce the highest ductility, or strength, or both. These highest properties would then be selected as characteristic of each alloy, and alloys would be compared on the basis of those properties. Thus a separation of the effect of composition and that of workiiig and heat-treating would be achieved. In this paper, however, a compromise with completeness has been made by carrying out a restricted number of treatments. As a consequence, the properties obtained are not necessarily the best that the alloy is capable of exhibiting; but since all alloy3 have been treated by the same method, the results ought to be comparable. The elements selected for the study comprise a class that will alloy easily with magnesium, and that are reblatively cheap. Each was added in different amounts, up to a limit that varied with the element.

Jan 1, 1940

By John C. McDonald

The amount of published literature in the field of mechanical properties of magnesium alloys is not great; particularly with respect to rolled alloys. Haughton and Prytherchl have summarized most of the articles to 1937, including their own work on sheet. Although many papers can be found dealing with the technology of magnesium and the alloys now in commercial use, there does not seem to be any work dealing exclusively with the variation in properties of rolled alloys as caused by changes in alloy composition. Comparison of published data reveals considerable discrepancies in properties of alloys of the same composition, probably due to differences in the details of working and heat-treating followed by different workers. The purpose of this paper is to study the properties of alloys in conditions where the effects of such differences have been eliminated. It is well known that the strength and ductility of metals are functions of the working and heat-treating they have received, as well as of their chemical composition. In comparing alloys with respect to these properties, therefore, all possible combinations of the variables of the fabrication procedure ought to be carried out on each alloy. One or more of these treatments mill produce the highest ductility, or strength, or both. These highest properties would then be selected as characteristic of each alloy, and alloys would be compared on the basis of those properties. Thus a separation of the effect of composition and that of workiiig and heat-treating would be achieved. In this paper, however, a compromise with completeness has been made by carrying out a restricted number of treatments. As a consequence, the properties obtained are not necessarily the best that the alloy is capable of exhibiting; but since all alloy3 have been treated by the same method, the results ought to be comparable. The elements selected for the study comprise a class that will alloy easily with magnesium, and that are reblatively cheap. Each was added in different amounts, up to a limit that varied with the element.

Jan 1, 1940

By Jim Douglas, H. H. Rachford, D. W. Peaceman

The problem of unsteady-state gas flow through porous media has been solved numerically only for the case of linear or radially symmetric reservoirs. A recently introduced numerical method for solving the unsteady-state heat flow equation in two dimensions is applied to the calculation of the depletion of a square region containing a perfect gas. Solutions are presented in graphical form for various values of dimensionless parameters. The solutions are compared with published .solutions for radial reservoirs. I NTR ODUCTION The problem of unsteady-state flow of gas through porous media gives rise to a second-order non-linear partial differential equation for which no analytical solution has been found. Numerical approximations to solutions of the gas flow problem have been obtained by the stepwise solution of an associated difference equation1,2. However, the methods so far developed have required that the reservoir be either linear or radially symmetric. This restriction in shape has been necessary so that only two independent variables be considered, namely, one distance variable and time. In order to deal with reservoirs having more realistic shapes, it is necessary to develop numerical procedures for the solution of the gas flow problem involving two distance variables. A numerical procedure, denoted as the alternating-direction implicit method, for the solution of the heat-flow problem in two dimensions has recently been introduced" By the use of this procedure, approximate solutions have been obtained for heat-flow problems in a square8, and in regions having various non-rectangular boundariesa. Because of the similarity between the equation for heat conduction in solids and the equation for gas flow in porous media, it is reasonable to expect that the alternating-direction implicit method should also be useful for solving the gas flow problem in various two-dimensional regions. Solutions have been calculated for the simplest two-dimensional region, a square reservoir with a single well in the center. While reservoirs of such simple geometry seldom, if ever, exist, the solution of this problem is of some practical importance because it is also the solution of another problem, that of determining the depletion history about an individual well in an infinite uniform reservoir containing wells spaced throughout on a square lattice and producing equally from each well. Finally, it is of interest to compare solutions for a square reservoir with those for a circular reservoir and to determine the effect of the shape of the boundary for that particular case. METHOD OF CALCULATION Basic Differential Equation By combining the equation of continuity, the perfect gas law,

Jan 1, 1956

By E. S. Fisher

GRAIN coarsening implies a discontinuous type of grain growth during which a few grains in a fine grained recrystallized matrix grow to large grain sizes at the expense of the matrix. Studies of this phenomenon in various metals1,2 indicate that grain coarsening may result when continuous grain growth in a fine grained matrix is inhibited by either a dispersion of very fine inclusions or by a strong texture. In the former case a period of annealing time exists prior to grain coarsening during which grain growth inhibition is gradually de- creased by dissolution or coalescence of the dispersed inclusions. This mechanism can be made to occur in uranium during anneals at high a phase temperatures. ' A study of some of the factors influencing the kinetics of grain coarsening and the coarse grain sizes in a uranium has led to a method for preparing a uranium single crystals. Previously such single crystals containing considerable substructure were prepared at this laboratory by a phase change method, similar to that described by Cahn.3 Attempts to prepare more perfect single crystals by strain-anneal techniques were unsuccessful. Cahn3- as reported his attempts to apply such techniques to uranium. He proposed that the failure of strain-anneal techniques is basically due to the many twins which

Jan 1, 1958

By W. L. Hill, W. H. Armiger, S. D. Gooch

The physical properties, chemical behavior under thermal treatment, and fertilizer value of fluorine-containing pseudowavellite (hydrous calcium aluminum phosphate) that occurs as phosphate clay admixed with quartz sand in an extensive deposit near Bartow, Fla., were determined by experiments in laboratory, pilot-plant, and greenhouse. When the mineral was heated at 500°C, 80 pct of the phosphorus became citrate soluble. The heated product, however, deteriorates markedly under moist conditions such as obtain in the soil.

Jan 6, 1950

By G. H. Clevenger

Discussion of the paper of ALLAN J. CLARK presented at the San Francisco meeting, September 1915, and printed in Bulletin No. 103, July, 1905, pp. 1381 to 1398. G. H. CLEVENGER, Palo Alto, Cal.-Since the precipitation of extremely dilute solutions as regards cyanide presents one of the greatest problems of zinc-dust precipitation, I should like to ask Mr. Clark the minimum concentration in cyanide of the solution from which it is possible to precipitate satisfactorily the gold with zinc dust in Homestake practice. A. J. CLARK.-For a day's work about 0.015 per cent. That is precipitating a very low-grade solution, very low in alkalinity. It requires probably 0.2 lb. of zinc dust to the ton. JOHN A. FULTON, Melones, Cal.-At the Melones mine, we have been working very low-grade rock for a number of years, the process being amalgamation and concentration up to the last year. The value of the ore increased so that we had to supplement the concentration with a sand and slime plant. Classification was a problem, since to install classifiers would mean tearing the mill all to pieces. We are therefore making use of a Wilfley table for this purpose. The amount of wash water is increased and a stream of fresh water is also run into the feed box at the

Jan 12, 1915