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By Charles D. Borror, George K. Foster

The Jeffrey mine of the Canadian Johns-Manville Co., Limited, is in the town of Asbestos, situated approximately 100 miles northeast of Montreal and about the same distance southwest of Quebec, in Richmond County, Quebec. Mining operations were started in 1881 on outcrops on a hill, as a side-hill cut, followed by a second and third cut. This development was the forerunner of the present large open-pit operations, the mine now ranking as the largest open-pit asbestos mine in the world. Operations were first carried on by hand, then by horsepower and later by stem cableways. By 1924 the derrick spans, 2000 ft. or more long, became unwieldy. To overcome this, and also to eliminate hand labor as much as possible, steam shovels and railroad haulage were introduced. The steam shovels were replaced in 1928 by larger electric shovels of the full-revolving type. The Ore Body The ore body is a serpentinized peri-dotite rock mass. The chrysotile fibers form a network of veins throughout, varying from microscopic width to two or more inches measured across the veins (Fig. I). These veins may be continuous for a few or many feet; they may increase or decrease in width within a few feet. The veins in which the fibers occur per- pendicular to the veins are known as cross fiber. Those in which the fibers lay parallel to the veins are known as slip fiber. The cross fibers are of better quality, and more in demand. The majority of the fiber

Jan 1, 1948

By George K. Foster, Charles D. Borror

The Jeffrey mine of the Canadian Johns-Manville Co., Limited, is in the town of Asbestos, situated approximately 100 miles northeast of Montreal and about the same distance southwest of Quebec, in Richmond County, Quebec. Mining operations were started in 1881 on outcrops on a hill, as a side-hill cut, followed by a second and third cut. This development was the forerunner of the present large open-pit operations, the mine now ranking as the largest open-pit asbestos mine in the world. Operations were first carried on by hand, then by horsepower and later by stem cableways. By 1924 the derrick spans, 2000 ft. or more long, became unwieldy. To overcome this, and also to eliminate hand labor as much as possible, steam shovels and railroad haulage were introduced. The steam shovels were replaced in 1928 by larger electric shovels of the full-revolving type. The Ore Body The ore body is a serpentinized peri-dotite rock mass. The chrysotile fibers form a network of veins throughout, varying from microscopic width to two or more inches measured across the veins (Fig. I). These veins may be continuous for a few or many feet; they may increase or decrease in width within a few feet. The veins in which the fibers occur per- pendicular to the veins are known as cross fiber. Those in which the fibers lay parallel to the veins are known as slip fiber. The cross fibers are of better quality, and more in demand. The majority of the fiber

Jan 1, 1948

By John A. Church

IT is a well-known fact that under similar conditions a ton of pig iron can be made from any ore with less fuel when charcoal is used than when coke or anthracite is employed for heating. The cause of this superiority is entirely undiscovered, and no explanation has yet been offered which has won even temporary acceptance. Such as they are the hypotheses heretofore presented are of two general kinds, and they come from those two divisions of the working force which are so often antagonistic in all professions, the scientific and the practical men. The theory of the scientific men is drawn from the chemical reactions which are known to go on in the furnace, and it is well expressed in a recent paper by Prof. Akerman, of the Stockholm (Sweden) School of Mines. It makes the superiority of charcoal as a fuel in the blast furnace to depend upon its quick and thorough reduction of carbonic acid. This property belongs to charcoal in virtue of its porous structure. Its cells have a diameter of only one twenty-four hundredth of an inch, and one grain of charcoal has been computed to have a surface of two and four-tenths square feet. According to the theory in question, carbonic acid is formed by the first impact of the air upon the fuel; but in charcoal furnaces the acid is immediately reduced to oxide by taking the necessary amount of carbon into combination, and the gas reaches its highest reducing power even in the near vicinity of the tuyeres. Coke, being harder, does not produce so strong a reducing gas in that part of. the furnace. Carbonic acid is formed as in the case of charcoal, and remains longer before its reduction to oxide is completed. Anthracite is the

Jan 1, 1879

By Frederic Becket

IN a recent article,1 which described the softening effect of columbium in plain high-chromium steels, the authors stated that their investi-gations had shown columbium to be also a particularly valuable inhibitor of intergranular corrosion in steels of the 18 per cent chromium, 8 per cent nickel type. It is the purpose of the present paper to record some of the results obtained through the introduction of columbium to the austenitic chromium-nickel steels. The damaging effects of this type of corrosion have become so widely known as to restrict considerably the applications of the steels under consideration, and therefore there is little question of the importance of the goal to be attained. Numerous contributions concerning the susceptibility of the aus-tenitic chromium-nickel steels to intergranular corrosion have appeared during the past few years, and among others who have dealt construc-tively with the subject are such well-known authors as Strauss and Houdremont of Germany, Hatfield of England, and Bain in the United States. Different theories have been propounded as to the cause of intergranular corrosion, and various remedial measures have been proposed, the majority of which involve the use of addition agents. Titanium is the addition agent at present most generally employed, as suggested by Houdremont and modified as described by Bain, Aborn and Rutherford.2 Little has been published on the effects of holding these steels for long periods at the relatively lower temperatures in the presence of

Jan 1, 1934

By Michael Tenenbaum, T. L. Joseph

Recent researches on the reduction of iron ores have stimulated interest in the effect of increased pressures within the iron blast furnace. From a physicochemical viewpoint, it seems logical to suppose that the increased pressure would increase the rate of reduction of the iron ore within the furnace. This increased reaction velocity would in turn be reflected in an increase in the output of the blast furnace. Any substantial effect of elevated blast-furnace pressures should accordingly be of both technical and economic interest to the operator. It is doubtful whether it is possible to increase the pressure in the stack of the blast furnace beyond two or three atmospheres without incurring severe mechanical difficulties. The benefits to be procured by elevations in pressure must therefore be restricted to pressures below two, or at the most, three atmospheres. Within this range it would seem both economically and mechanically feasible to modify the present design of the upper portion of the blast furnace to accommodate these more stringent operating conditions. This investigation was undertaken to study the effect of moderate pressures on the rate of reduction of iron ore with hydrogen. The use of carbon monoxide is contemplated for later work. Although any results that are obtained in the laboratory cannot be interpreted directly in terms of large-scale commercial operations, it is possible, through such an investigation, to ascertain the order of magnitude of the effects of higher pressure. A more quantitative conception of the effects that would result from the use of increased pressures in the modern blast furnace is needed. In some recent work, Diepschlagl found that, all other factors remaining constant, the degree of reduction of iron ores was much greater when carried out under pressure. Pressures as high as seven atmospheres were used. The degree of reduction was determined from the ferrous and ferric iron in the sponge iron. Results were obtained using both carbon monoxide and hydrogen at temperatures of 400°, 600° and

Jan 1, 1939

By Michael Tenenbaum, T. L. Joseph

Recent researches on the reduction of iron ores have stimulated interest in the effect of increased pressures within the iron blast furnace. From a physicochemical viewpoint, it seems logical to suppose that the increased pressure would increase the rate of reduction of the iron ore within the furnace. This increased reaction velocity would in turn be reflected in an increase in the output of the blast furnace. Any substantial effect of elevated blast-furnace pressures should accordingly be of both technical and economic interest to the operator. It is doubtful whether it is possible to increase the pressure in the stack of the blast furnace beyond two or three atmospheres without incurring severe mechanical difficulties. The benefits to be procured by elevations in pressure must therefore be restricted to pressures below two, or at the most, three atmospheres. Within this range it would seem both economically and mechanically feasible to modify the present design of the upper portion of the blast furnace to accommodate these more stringent operating conditions. This investigation was undertaken to study the effect of moderate pressures on the rate of reduction of iron ore with hydrogen. The use of carbon monoxide is contemplated for later work. Although any results that are obtained in the laboratory cannot be interpreted directly in terms of large-scale commercial operations, it is possible, through such an investigation, to ascertain the order of magnitude of the effects of higher pressure. A more quantitative conception of the effects that would result from the use of increased pressures in the modern blast furnace is needed. In some recent work, Diepschlagl found that, all other factors remaining constant, the degree of reduction of iron ores was much greater when carried out under pressure. Pressures as high as seven atmospheres were used. The degree of reduction was determined from the ferrous and ferric iron in the sponge iron. Results were obtained using both carbon monoxide and hydrogen at temperatures of 400°, 600° and

Jan 1, 1939

By J. B. Morrow

WITH numerous plans under consideration for coal classification, and with the advent of the Bituminous Coal Code, the intelligent sam-pling of coal has become increasingly important. To us it is rather significant that there have been very few fundamental studies of coal sampling in American technical literature since those of E. G. Bailey, which appeared in the Journal of Industrial and Engineering Chemistry in March, 1909. He covered the subject up to that time so thoroughly and in such an excellent manner that perhaps many other later students have felt that they could add very little to his findings. The recent studies of the British Engineering Standards Association have indicated the possibility of a somewhat different interpretation of Bailey's results, permitting the taking of smaller samples, and perhaps it will now be helpful to reopen this question. C. W. H. Holmes, in an informative series of articles on coal sampling recently published in Colliery Engineering, makes two rather interesting statements, as follows: It is scarcely surprising to find a lack of interest and knowledge regarding the sampling of coal not only in the mining industry itself but also among consumers of industrial fuel: at its best coal sampling is a dirty business, regarded as a nuisance and an expense by the commercial man, and usually as a nuisance and nothing else by the chemist. The writer can conceive only two classes of people who have never experienced any difficulty in obtaining representative samples of coal from wagons; those who have never tried to, and those who have never had the necessity or desire to check the accuracy of their work. The primary purpose of this paper is to present some tabulated data of the more significant results of a sampling investigation undertaken during the last four years to obtain certain fundamental data on the variables connected with coal sampling and to point out that often assumptions have been made that are not in accordance with the facts. One of the standard sampling methods states:

Jan 1, 1935

By Paul E. Dorr, Kenneth P. Pavlich

This paper covers the practical aspects of economic analysis of mineral ventures and the application of a publicly available computer program. The paper touches briefly on the time value of money concepts and the phases of project evaluation. The most comprehensive port ion of the paper deal s with the requirements for economic evaluation, including capital expenditure categories, operating expenses, required geological and engineering data, and tax considerations. Highlights of the 1981 and 1982 tax laws are covered. A case study using the MINECO computer program will be used to illustrate the economic evaluation concepts developed. Guidelines and goals of sensitivity analysis and Monte Carlo simulation will be discussed and demonstrated on the MINECO example. The MINECO software system will be displayed as an example of a "user-friendly", interactive, and flexible computer tool available to the mining professional today.

Jan 1, 1983

By Joshua I. Tracey, Mackenzie Gordon

THE bauxite deposits in central Arkansas were formed by weather¬ing, in early Eocene time, of fresh or kaolinized nepheline syenite above the water table in a subtropical climate of fairly continuous moisture. Four types are recognized: (1) residual bauxite deposits on kaolinized nepheline syenite, (2) residual deposits on kaolin and bauxite detritus, (3) alluvial deposits of sorted pebbles and pisolites of early Wilcox age, and (4) rubble deposits of later Wilcox age. All were invaded by kaolin and siderite during subsequent burial by Eocene sediments. PART I-FIELD RELATIONS OF THE DEPOSITS The Arkansas bauxite region for years has produced about 95 pct of the domestic supply of bauxite of the United States and it contains today reserves of more than 40 million tons-nine tenths of the known domestic reserves. During World War II, the Arkansas bauxite deposits were explored jointly by the U. S. Geological Survey and the U. S. Bureau of Mines. Some 6000 holes were drilled by rotary rigs under contract to the Federal Govern¬ment, which resulted in the discovery and delimiting of approximately 20 million tons of ore in place. Detailed study of the many sections cored through the bauxite, of data from a much greater number of drill holes made available by all the operating companies, and of the extensive mine faces exposed in the strip pits, has yielded valuable geologic information about the origin of the deposits. It is now possible to piece together a paleotopographic picture of the deposits and the now-buried land surface on which they formed. The bauxite region in the center of Arkansas (Fig 1) contains two producing districts: one in Pulaski County, just south of Little Rock, and the other in Saline County, about 15 miles to the southwest. The deposits in both districts are associated with hills of nepheline syenite, bosses of a large batho¬lith that was intruded into Paleozoic rocks and later buried beneath coastal plain sediments deposited during Cenozoic time. The folded Paleozoic rocks are exposed in the northwest half of the state and are covered in the southeast half by the nearly flat-lying coastal plain sediments. The older rocks were intruded by nepheline syenite, probably in Late Cretaceous time, and sub¬sequently were eroded so as to expose the top of the batholith. In Paleocene time, marine limestone and laminated black silty clay of the Midway group were deposited in an advancing sea, and covered all but the most elevated parts of the batholith. Erosion of the islands of nepheline

Jan 1, 1952

By F. V. Shallcross

Physical properties of thin films of CdS and CdSe formed by vacuum deposition onto glass sibstrates have been studied as a function of deposition and processing conditions. The crystallinity and surface features of CdS films were examined using electron microscopy and electron and X-ray diffraction techniques. The films were poly crystalline; the preferred orientation and crystallite size increased with film thickness, substrate temperature, and deposition time. The CdS films consisted primarily of hexagonal-phase material, in contrast to similarly prepared CdSe films which have previously been observed to contain mixtures of cubic and hexagonal phases. As-deposited CdS films showed no major dependence of Hall mobility on crystallite size or degree of preferred orientation. Hall mobility and carrier concentration in CdS and CdSe .films were measured at various temperatures; both parameters increased with temperature and yielded activation energies which depended on fabrication conditions. Surface-desorption phenomena and overcoating of the semiconductor with SiO affected the observed electrical properties significantly. THIN films of cadmium sulfide1,2 and cadmium sele-nide3,4 have been employed by various workers as semiconductors in the insulated-gate thin-film field-effect transistor, known as the TFT. These devices are most commonly made by vacuum deposition of all materials onto an amorphous substrate such as glass. A knowledge of the microstructure and electrical properties of semiconductor layers used in the thin-film transistor is essential in order to form a realistic model for the device and to improve its performance, reproducibility, and reliability. This paper will describe studies of the physical properties of vacuum-deposited CdS and CdSe films prepared under various conditions. Structural characteristics examined in- cluded phases present, crystallite size, nature of preferred orientation of crystallites, surface roughness, and structural homogeneity throughout the film thickness. Electrical properties measured were Hall mobility and conductivity and their dependence on temperature and ambient. Thin-film properties are affected by many fabrication parameters including purity and physical form of evaporant, deposition rate, film thickness, design and temperature of the evaporation crucible, geometry of the deposition chamber, nature of the residual atmosphere, composition and temperature of the substrate, and details of postdeposition processing. PREPARATION OF FILMS In this work the semiconductor films were deposited in a conventional oil-diffusion-pumped system with pressures in the 10-8 torr range. The CdS evaporant was obtained from the Eagle-Picher Co. as a high-purity coarse-grained crystalline powder; the CdSe was a high-purity sintered powder supplied by the Harshaw Chemical Co. The evaporation crucible was a resistance-heated molybdenum-wire basket coated with aluminum oxide and filled with a quartz wool plug at the top. The source to substrate distance was usually 10 cm. This region was enclosed by a Pyrex inner cylinder. The substrate was heated with an overlying Pyrex plate coated with tin oxide. The substrate temperature was controlled using a thermocouple attached to the lower side of the heater. This thermocouple was calibrated against another thermocouple attached to a dummy substrate and by observation of melting points of various metal films deposited in the system. The substrates were polished borosilicate glass plates and conventional glass microscope slides. Substrate preparation included cleaning with an ultrasonically agitated detergent bath followed by isopropanol-vapor de-greasing. Film thickness was measured interferomet-rically during and after deposition. STRUCTURE OF CdS FILMS Structural studies were performed on CdS films using electron diffraction, electron microscopy, and

Jan 1, 1967

By R. Hadfield

Last year this institute was good enough to accept some remarks by the writer regarding sound steel, entitle Plant for Hadfield Method of Producing Sound Steel Ingots…

Jan 1, 1915

By H. J. Struth

In these trying times of proration and low oil prices, it is decidedly necessary for all branches of the petroleum industry to accord full recognition to the economic phenomena that contribute to its varying state of welfare. Perhaps no other single factor has a more important bearing upon the general oil situation than the supply and demand of gasoline. Year after year, the records have shown that the degree of prosperity or depression accompanying the industry's developments has been to a large extent influenced by the degree of balance maintamed between the supply and demand of gasoline. More and more it is being realized within the industry that equilibrium between the supply and demand of gasoline forms the basic structure of crude and product market values and, consequently, the deciding factor in the financial results of the industry as a whole. The influence of the gasoline situation upon the market and financial structure of the petroleum industry was effectively demonstrated during 1930, when excess accumulation of gasoline undermined not only the refined oil market but the crude market as well. In fact, it was a top-heavy gasoline situation that defeated the realization of benefits that might have accrued from an otherwise favorable statistical position in the producing branch of the industry. Indicative of this is the fact that crude oil production was curtailed to the extent of 98,323,000 bbl. last year, while refinery runs to stills were maintained at an excessive rate until late in the year, creating an excess gasoline production of 6,663,000 bbl. above actual requirements. Nevertheless, the movement to curtail refinery operations during the closing months of the year prevented a far worse situation, although it came too late to turn the ebbing momentum of the general oil market. Despite the severe depression of the market values that accompanied 1930 developments, it can be said that the results attained during the closing months of the year, in the direction of production control, marked a decisive turn in the industry's economic affairs. In fact, a review of the oil situation from every angle points definitely to a better general understanding and recognition of the workings of the economic law of supply and demand. As a result, the year closed with crude production in

Jan 1, 1931

By C. A. Heiland

Measurements of gravity with gravimeters have come into increased use in this country and abroad in the past five years. Probably 100 to 125 gravimeter parties are working in the United States alone. In oil exploration, gravimeter methods have relegated the gravity pendulum definitely to second place, if not third, and now closely rival and possibly surpass the torsion balance in many applications. Gravimeters have lately been applied in mining, although it is doubtful whether they will ever replace electrical or magnetic methods in this work. Notwithstanding the widespread application of gravimeters, there has been no article covering the entire field in the domestic or foreign literature. The purpose of this paper is to meet the demand for comprehensive engineering information on the subject. The working principles of a number of gravimeters will be illustrated and treated in relation to the action of corresponding seismometers and astatization methods. The mathematical discussion of theory has been confined to the most necessary fundamentals and been given in as elementary form as possible. A description of calibration methods constitutes the last part of the paper. The symbols shown at the top of page 197 will be used in equations throughout the paper. Dynamic and Static Gravity Methods Methods of measuring gravity fall into two groups: dynamic and static methods. The first group involves the measurement of time. Examples are: determinations of the period of oscillation of a pendulum, measurements involving the free fall of a body, and comparisons of gravity with the centrifugal force of a rotating body. Measurements in the second group of gravity methods are concerned with deflections of certain indicators when the force of gravity is in equilibrium with another comparison force.

Jan 1, 1940

By C. A. Heiland

Measurements of gravity with gravimeters have come into increased use in this country and abroad in the past five years. Probably 100 to 125 gravimeter parties are working in the United States alone. In oil exploration, gravimeter methods have relegated the gravity pendulum definitely to second place, if not third, and now closely rival and possibly surpass the torsion balance in many applications. Gravimeters have lately been applied in mining, although it is doubtful whether they will ever replace electrical or magnetic methods in this work. Notwithstanding the widespread application of gravimeters, there has been no article covering the entire field in the domestic or foreign literature. The purpose of this paper is to meet the demand for comprehensive engineering information on the subject. The working principles of a number of gravimeters will be illustrated and treated in relation to the action of corresponding seismometers and astatization methods. The mathematical discussion of theory has been confined to the most necessary fundamentals and been given in as elementary form as possible. A description of calibration methods constitutes the last part of the paper. The symbols shown at the top of page 197 will be used in equations throughout the paper. Dynamic and Static Gravity Methods Methods of measuring gravity fall into two groups: dynamic and static methods. The first group involves the measurement of time. Examples are: determinations of the period of oscillation of a pendulum, measurements involving the free fall of a body, and comparisons of gravity with the centrifugal force of a rotating body. Measurements in the second group of gravity methods are concerned with deflections of certain indicators when the force of gravity is in equilibrium with another comparison force.

Jan 1, 1940

By D. E. Hartman, J. M. Roberts

A detailed study of the temperature dependence of the critical stress, TB . necessary to cause a damping loss of 1.41 x 10-6 g mm per mm3 in pre-strained magnesium single crystals has been carried out in the temperature range 82" to 320°K. Tb is found to be linearly related to the reciprocal of the ahsol~cte temperature in this temperature range. The temperature dependence of the anelastic limit, TA, defined as the stress necessary to form open unidirectional stress-cycle damping loops has been measured between 82" to 320°K. ta is found to be independent of temperature in this range. It is suggested that TA is determined by the stress necessary to activate Frank-Read dislocation NUMEROUS studies1-9 have been reported concerning the details of yielding and microstrain near and below the generally discussed macroscopic flow stress. The work of Kramer and coworkers10-13 is helpful in determining certain qualitative facts. concerning preyield phenomena. The absence of a stress-dependent delay time in annealed copper and aluminum single crystals between 83" and 298 suggests that the preyield mechanism is temperature-independent in this range. This is not sources. The temperature and stress dependence of the effective activation volume (Veff) has been measured in the damping-loop region in prestrained magnesium single crystals. The data suggests that Veff/kT is approximately constant, equal to 2 4.5 sq mm per g in the temperature range 130°to 298°K, and that Veff is almost independent of stress at stress levels greater than 10 g per sq mm. A restricted model is developed to predict the stress (rb) necessary to cause a small fixed damping loss as a function of temperature, effective activation volume, and dislocation density. Various possible dislocation mechanisms controlling TB are discussed. true for zinc, p brass, and iron crystals in the same temperature range, however, since the existence of a stress-dependent delay time suggests a thermally activated preyield mechanism in these materials.10-13 The work by Vreeland et a1.14 confirms the work by Liu et al.ll on delayed yielding in zinc single crystals. A stress-dependent delay time between 82" and 298°K was found12 in prestrained aluminum and copper crystals. These results suggest that the preyield phenomena may be different between prestrained and unstrained or annealed crystals. The temperature dependence of the yield point at 2 x 10-8 plastic strain found by Rosenfield and Averbach3 in annealed copper and aluminum is not in agreement with the delay-time data, unless possibly the delayed yielding experiment only de-

Jan 1, 1964

By John Wulff, H. H. Uhlig

Since its first mention in the literature in the eighteenth century12 the phenomenon of passivity in metals has stimulated much speculation and attendant controversy as to its nature and cause. No one of the numerous theories so far proposed has been generally accepted. ‡ Faraday,' in 1836, associated the passivity of iron with a protective film over the surface of the metal, which materially prevents or slows down reaction with corrosive environments. His theory was that oxidizing acids like nitric acid form an unstable oxygen or oxide layer over the iron surface, which protects the underlying metal from further attack. This concept was simple yet plausible, and without alteration has frequently been assigned in present-day discussions as explanation of the passivity of many metals. With the advent in recent times of stainless steels, it is not surprising that this oxide film theory of passivity proposed by Faraday has been used to explain the phenomenal corrosion resistance of stainless steels and other passive alloys. The passive alloys, such as the chrome-iron alloys, are supposedly covered with a protective oxide film, which forms on exposure of the alloy to air, is extremely stable and self-healing, and accounts for the remarkable resistance of these alloys to corrosion. Within the past few years, several investigators, following the theory of film protection, have attempted to gauge the resistance of the supposed film on steels. Brennert8 and Donker and Dengg9 determined the potential at which a negative ion (e.g., C1-) moving in an electric field reacted with the metal anode, as detected by increased current flow or change in potential of the steel electrode in an electrolytic cell. The potential corresponding to reaction Brennert called the film break-through potential.

Jan 1, 1939

By John Wulff, H. H. Uhlig

Since its first mention in the literature in the eighteenth century12 the phenomenon of passivity in metals has stimulated much speculation and attendant controversy as to its nature and cause. No one of the numerous theories so far proposed has been generally accepted. ‡ Faraday,' in 1836, associated the passivity of iron with a protective film over the surface of the metal, which materially prevents or slows down reaction with corrosive environments. His theory was that oxidizing acids like nitric acid form an unstable oxygen or oxide layer over the iron surface, which protects the underlying metal from further attack. This concept was simple yet plausible, and without alteration has frequently been assigned in present-day discussions as explanation of the passivity of many metals. With the advent in recent times of stainless steels, it is not surprising that this oxide film theory of passivity proposed by Faraday has been used to explain the phenomenal corrosion resistance of stainless steels and other passive alloys. The passive alloys, such as the chrome-iron alloys, are supposedly covered with a protective oxide film, which forms on exposure of the alloy to air, is extremely stable and self-healing, and accounts for the remarkable resistance of these alloys to corrosion. Within the past few years, several investigators, following the theory of film protection, have attempted to gauge the resistance of the supposed film on steels. Brennert8 and Donker and Dengg9 determined the potential at which a negative ion (e.g., C1-) moving in an electric field reacted with the metal anode, as detected by increased current flow or change in potential of the steel electrode in an electrolytic cell. The potential corresponding to reaction Brennert called the film break-through potential.

Jan 1, 1939

By J. H. Henderson, H. J. Ledbetter, N. B. Gove, J. D. Griffith

INTRODUCTION The results of a series of laboratory flood tests using liquid Iso-butane to displace refined oils from test cores are pre- ented and interpreted on an empirical bask. The study Revealed the similarity of the miscible liquid displacement to that of the immiscible-fluid displacement mechanism. The efficiency of the iso-butane flood decreased markedly as the oil Viscosity increased. but the effect of injection rate on the effectiveness of the primary production stage was negligible over the range investigated. The presence of free-gas saturation prior. to iso-butane breakthrough increased the volume of iso- Butane required to recover a given percentage of the oil present. Injection of liquid i.e.-butane prior to water follicle sculpted in a marked improvement in oil recovery by the water flood. INTRODUCTION The production of petroleum is often enhanced by the injec-1i1)n of extraneous fluids into the reservoir. It has been suggeited that the injection or cycling of a wet gas or a liquefied petroleum gas would he instrumental in increasing the effic.ienr!; of oil recover! to a greater degree than the commonly injected fluids. dry pas and water. Although instances of injection of light liquid hydrocarbons are not unknown, a systrmatic recording of the result is unavailable and superfi- cially, the practice gives the impression of being economicaIIy unsound. For specific types of displacement, analytic: solutions have been advanced which aid in understanding the physical mechanisms involved. However, there is no generalized theoretical concept which permits adequate prediction of displacement efficiency from a knowledge of readily measured reservoir rock and fluid properties. The Buckley-Leverett approach to oil displacement by an immiscible phase is an admirable analysiy of that type of mechanism. Dykstra and Parsons have introduced a useful concept in their evaluation of the role of the mobility ratio and its merit in rationalizing displacement phenomena. Everett, Gooch and Calhoun3 in their report on the effect of viscosity ratio and miscibility have pointed out the lack of a comprehensive theoretical approach and the desirability of investigating the mechanism of miscible-miscible displacement. In lieu of a well-developed theory concerning miscible-111isci1)le displacement and in view of the scarcity of engineering information on actual LPG injection trials, the limited program of laboratory experimentation described below was undertaken. OBJECTIVES The original broad objectives of the program, to study the oil recovery process using LPG as the displacing phase, defined the direction and scope of the laboratory tests. The specific objective. of the experimentation were to evaluate

Jan 1, 1953

By Albert Ledoux

SEVERAL years ago my firm was representing the Mt. Lyell Co. of Australia, which was shipping its blister copper to a refining works in the United States. After the contract had been running for many months, the superintendent of these works discovered that if water was poured upon the surface of the bars much of it would disappear into the interior through blow holes. -Some experiments made by him showed that this could be a considerable amount, so that copper which had been rained on before it was weighed, although the surface appeared dry, nevertheless would contain water. It had frequently occurred in our experience-as samp-lers that the drillings from a lot taken by boring would come out quite wet, and in some cases, indeed, water would drip into the sample pan placed below the bars, due to the fact that the drill had penetrated a cavity or cavities containing water, which presumably got into the cavities at the time the copper was water-cooled after casting, there being, perhaps, no outlet to the surface. So far as I know, until this discovery at the refining works, no. one had thought that rain could penetrate into the interior of blister copper; at least in any quantity sufficient to be considered.

Jan 10, 1922

By Galen G. Waddell

Several years of rock-burst research conducted by the U.S. Bureau of Mines in cooperation with the mining companies of the Coeur d'Alene mining district, Idaho, in addition to progress made by others throughout the world, have led to a good understanding of the rock-burst problem. This paper describes conditions which have caused specific bursts, present capabilities of detecting stress buildup and bursts, control methods, and a suggested approach to analyzing any individual mine-burst problem. A rock burst is the sudden, violent release of stored strain energy in rock by some mechanism of rock failure, generally accompanied by expulsion of rock with consequent damage to the mine. A burst may be audible for only a few hundred feet, or on the surface it may sound like a sonic boom miles away. A Dictionary of Mining, Mineral, and Related Terms, U.S. Bureau of Mines (USBM)* 1968yand defines a burst as Bureau "That phenomenon which occurs when a volume of rock is strained beyond the elastic limit and the accompanying failure is of such a nature that accumulated energy

Jan 1, 1971