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IF you do not make the disc at the same time as the core and as part of it, it is necessary to make it by itself. This is done by spreading on a board or other flat surface a layer of clay as thick and wide as [88] the disc that you made at the feeding head of the first pattern of the gun. When it is dry, mark it exactly with compasses and then, cutting with a chisel or rasp, make it fit exactly into the empty space at the head. Likewise, make a hole just as wide as the thickness of the core exactly in the middle of this clay disc. When you have put the disc in its place in the mould and then pass the core through this hole, it passes exactly through the center of the mould in such a way that it meets the iron ring that you put at the foot of the mould for this purpose. As I said above, if' you do not make it as part of the core, it is necessary to proceed in the aforesaid way. But if' you wish to make it attached to the core (which I like better because it can be done more accurately) make a

Jan 1, 1942

By Robert Gorham Morse

This paper presents the results of an investigation made in the metallurgical laboratory of Columbia University, New York City. The object of the investigation was to determine how the tensile strength, the elastic limit, and the size of the grain, of a pure medium-carbon steel are affected by heating to successive temperatures between 500° and 1300° C., with slow cooling therefrom. Since Dr. Sorby's first investigations into the microstructure of steel, the study of the subject has been continued by Professor Martens, Mr. F. Osmond, Professor Arnold, Professor Howe, Mr. A. Sauveur, Mr. J. E. Stead, and many others. Among many valuable and interesting papers I mention the following as having a special bearing upon this investigation.* " Microstructure of Steel," by Albert Sauveur, Trans., xxii., 546 (1893); Microscopic Metallography," by F. Osmond, Trans., xxii., 243 (1893); "The Microstructure of Steel and the Current Theories of Hardening," by Albert Sauveur, Trans., xxvi., 863 (1896); "The Crystalline Structure of Iron and Steel," by John Edward Stead, J. Iron and Steel Inst., 1898. II.—Statement of Experiments. Through the kindness of Mr. N. Lilienberg, New York City, round rods 3/4 of an inch in diameter were obtained, which had been rolled from one ingot. The analysis of the steel was as follows : C, 0.343; Si, 0.027; Mn, 0.221; I?, 0.0266; S, 0.0037 per cent.

Jan 1, 1900

By Benjamin Miller

FROM earliest recorded times, limestone has been employed in the industrial life of peoples of all sections of the world where it exists. It is widely distributed and therefore has been available in almost every country and has been employed for a variety of purposes. Its earliest use was for buildings, since it is more easily quarried and dressed than most other kinds of rocks and so could be utilized by early inhabitants, poorly equipped with tools. The next use was in the manufacture of lime, which was employed by the ancients in mortar. These two uses of limestone are still all important, but they have been overshadowed in scores of regions by literally hundreds of new applications for raw lime-stone or products made from it. Anyone familiar with modern manufacturing processes can quickly call to mind many industries in which limestones are essential, and new uses are continually coming to notice. Any enumeration would probably be incomplete and soon out of date.

Jan 1, 1935

By Raymond B. Ladoo

The Paley report made little attempt to project future production and consumption for any industrial mineral except fluorspar and only about a dozen minerals were mentioned by name. Except for fluorspar the treatment consisted mainly of statistics of production, consumption, imports, and sometimes reserves up to 1950. FLUORSPAR In 1954 the author had occasion to evaluate the Paley fluorspar estimates. At that time a fairly detailed study of the world picture was made and bases for the Paley estimates were studied. Data for later years confirm, in the main, the conclusions reached in this earlier report and it will be drawn upon here.

Jan 11, 1959

By John A. Church

The operations of the Tombstone Mill and Mining Company, in Arizona, have been extensive and interesting; and I will eudeavor to describe what is novel in their work, without attempting to go over the well-known facts of silver milling, concentration and smelting which are the general branches of their business. Their mines are at Tombstone, and their mills at Charleston, ten miles distant. The ore has been mined only above water-level, and at first was

Jan 1, 1887

By H. Pew, J. H. Field

To alleviate pollution more restrictive legislation is being enacted, either limiting emission of pollutants or the type of fuel that can be utilized. The nature and magnitude of air pollution problems affecting the mining, preparation, coking and combustion of coal are described. Methods for combatting particulate emissions by use of mechanical separators and electrostatic pre-cipitors are discussed. Proposed methods to meet the problem of gaseous emissions currently receiving considerable attention are described, with special emphasis on methods to decrease pollution by sulfur oxides. Concern about air pollution goes back several centuries, but until very recently most effort has been aimed at coal smoke and other visible pollutants. The classic example of a 'successful' campaign for smoke abatement and control is the fruitful combined effort of the city of Pittsburgh and its surrounding Allegheny County, which eventually led to the reconstruction of downtown Pittsburgh at an estimated cost of one billion dollars. Historically, the city's downtown Golden Triangle district had been afflicted by pollutants evolving from steel mills, from a variety of other industries, and from railroad locomotives. Efforts to alleviate the situation prior to 1943 were virtually ineffective. In 1945, however, a comprehensive redevelopment plan was prepared and backed by state authority. Within a few years a clean, modern metropolis has evolved where once stood America's famous 'smoky city.' But the victory in Pittsburgh, as in various other American cities, has not solved the national problem. Current estimates indicate that 133 million tons annually of air pollutants from all sources still are emitted annually into the atmosphere above the United States. About 10% of this annual effluent is particulate matter so that most of the remaining pollution problems will be solved only when other effluents are reduced. Essentially, these are sulfur oxides, nitro- gen oxides, hydrocarbons, and carbon monoxide. Over the years, both states and local communities have tended to increase the restrictions on smoke and fly ash — problems mostly of concern in the combustion of coal. Prior to the middle 1950's, ordinances sometimes permitted emissions of smoke equivalent to as much as No. 3 on the Ringlemann scale. Since 1956, no ordinance has been passed which allows smoke of greater than No. 2. Under today's conditions of improved fuels, equipment and practice, a few communities have passed laws prohibiting emission of smoke of any density darker than Ringlemann No. 1. The majority of existing laws on fly ash emission in the U.S. limit emissions equivalent to 0.85 lb of fly ash per 1000 Ib of flue gas. In recent years, however, regulations which have been adopted give cognizance to the higher level of performance now obtainable with improved equipment. A comparison of the restrictions of five codes adopted since 1960 is given in Table I. The most stringent of these is the one for New York City which provides for a maximum emission of 0.6 lb fly ash per million Btu heat release (equivalent to roughly 0.51 lb/1000 lb of flue gas). The first comprehensive effort to restrict the emission of SO2 resulted from the passage of a 1937 law in St. Louis. This regulation stipulated that coal containing in excess of 23% volatile matter and 2% sulfur must be washed, thereby presumably producing some effective reduction in the input sulfur content. This was followed in 1949 by a Los Angeles County law which prohibited the emission of SO2 in concentrations greater than 0.2%. Most SO2-restrictive legislation passed since that date has been based on this limiting 0.2% SO2 by volume, although modifications are occasionally permitted under selected conditions, sometimes based on the fact that certain limiting ground concentrations are not exceeded — such as in the rules adopted by the San Francisco Bay area. To date, no legislation has been passed in the U.S. to limit the generation of nitrogen oxides from the combustion of fossil fuels. However, such oxides are considered to be of potential importance in air pollution control because of their possible detrimental effects on health and their reported role in the formation of photochemical smog. Interest in reducing oxides of nitrogen from powerplant and auto exhausts is increasing and regulations limiting their quantity can be expected in the future.

Jan 1, 1968

By R. G. Burdick, W. R. Peters

Shallow underground voids resulting from early coal mining and other resource recovery activities over the past several decades are now being recognized as a significant cause of ground subsidence problems. Uncertain knowledge of abondoned coal mines also imposes potential hazards in current underground mining operations, since water inundation or the release of methane gas is a serious hazard when mine excavation operations break into an abandoned mine. Requirements for detecting and mapping subversive manmade tunnels in previous work has led to the development of a surface-operated automatic earth resistivity survey system and associated computer data reduction process for military applications. Field demonstration tests of this system have resulted in successful detection of tunnels at depth-to-diameter ratios greater than 10 to one. Under the sponsorship of the Bureau of Mines, a similar high-resolution earth resistivity system was designed and constructed for use as a potential means of detecting abandoned coal mine workings. The hardware and software aspects of third new system are described together with applications of the method for surveying and mapping abandoned coal mine workings. Field tests are presented to illustrate the detection of both air-filled and water-filled mine workings.

Jan 1, 1984

By C. S. Allen

WITH increased coal production and mechanization of coal mines many transportation problems arise. The main objective is to bring the coal to the tipple or dump it as quickly as possible. Larger and faster haulage locomotives or two locomotives connected in tandem have been adopted to solve the problem. Motor equipment, gears and control systems of locomotives to be placed on these hauls are carefully studied to meet these requirements, by an analysis of motor characteristic curves with the corresponding tractive effort curves, in order to determine the correct load for maximum efficiency and to determine the approximate schedule. Control equipment is usually considered to be the controller and resistance. Sometimes accelerating curves are calculated in order to obtain smooth starting in the least possible time without slipping the wheels. Train control is very important, but why limit this to acceleration? Deceleration or retardation of the locomotive is a part of the train control and should be given as much consideration as the control for acceleration. TYPES OF BRAKING Common braking systems for mine locomotives utilize screw-type mechanical brakes, dynamic braking and the air brake. For gathering and haulage locomotives, the screw-type mechanical brake is regarded as standard. A brake of this kind cannot be applied without much effort and lapse of time. Motormen, like other people, follow the path of least resistance, and therefore have their brakes ready for instant application-which means that the shoes are virtually dragging. Even then, a motorman bucks and plugs the motors to gain time and avoid as much physical effort as possible. "Bucking of motors" consists in turning the reverse cylinder of the controller to parallel position corresponding to the opposite direction of travel while the locomotive is in motion, without applying power from an external source. When this occurs, both motors tend to act as series generators, because the armatures are revolving and there is residual magnetism in the field circuit. Owing to slight differences in motor manufacture, one of these will generate a slightly higher potential and will overcome the generated voltage of the second and tend to drive it as a motor in the reverse direction. This action retards the locomotive but is very severe on the segments of the reverse cylinder and on the motor commutators. "Plugging motors" is the application of power to the motors corresponding to the opposite direction of travel. In order to "plug" the motors it is necessary first to "buck" them (which reverses the connections to the motors) and then to apply

Jan 1, 1941

By David Reger

THE value of carbon ratios in determining the boundaries of possible oil deposits appears to have passed the hypothetical stage. The theory that the ratio of fixed carbon in pure coals is an, invariable index of incipient metamorphism in both, surface and underground rocks and that it may be applied in defining the limits of petroleum, advanced by David White,1 has been received with keen interest by many petroleum geologists. Detailed isocarb maps have been prepared of the Pennsylvanian area of North Texas and Eastern Oklahoma by M. L. Fuller.2 A similar map of the coal-bearing area of West Virginia is given here. An isocarb3 is a line showing an equal fixed-carbon percentage, pure coal basis; the term has been proposed by David White to supersede a less expressive nomenclature. The term carbon ratio is applied to the percentage of carbon in pure coal after water and ash have been eliminated. As a comparatively small number of analyses have been made on this basis, it is usually necessary to compute the ratio by dividing the fixed carbon of the proximate analysis by the sum of the fixed carbon and volatile matter of the same analysis. Many thousands of proximate analyses have been made by the West Virginia Geological Survey, covering nearly every county in which coal is found. Numerous others have been made by the. U.S. Geological Survey and the U. S. Bureau of Mines, but as uniformity of results is

Jan 2, 1921

By J. N. Roberts, K. V. Gow

In a recent review of the field of plastic deforrnation of metal single crystals, Maddin and chenl indicated the need for systematic investigations of the crystallography of the slip process with special attention to: a) The effect of the orientation of a crystal on the appearance of slip lines, b) The effect of high temperatures on the slip systems of aluminum, c) The effect of strain rate on the crystallography of slip. The present paper deals with the effect of temperature and strain rate on the mechanism of deformation of aluminum single crystals similarly oriented for single and duplex slip. The work of several investigators has shown that in aluminum at high temperatures other slip systems in addition to the predicted {I l l) <101> may operate. The most generally reported additional systems

Jan 1, 1959

By Sir James Kitson

By the courtesy of the President and Council of the American Institute of Mining Engineers, I have been invited to take the chair and open the proceedings of this congress. It is a graceful compliment to those members of the Iron and Steel Institute who are your honored guests at this moment—an acknowledgment of high consid-

Jan 1, 1891

By S. F. Shaw

The Sierra Mojada mining district is situated in western Coahuila, about 8 km. east of the Chihuahua state line, and about one-half way from the northern to the southern extremity of the state. It is at the terminus of the Mexican Northern R. R., 125 km. northeast of Escal6n, Chihuahua; also about, 240 km. due west of Monclova, Coahuila. The altitude is approximately 1500 m. above sea level. The Sierra Mojada valley is about 10 km. long, from east to west, with a width of 1 to 2 km. It is approached from the east through the Puerto del Oro, where the Mexican Northern R. R. enters the valley; the slope from west to east is gentle. The Sierra Mojada, of which about 300 m. is an almost vertical wall, bounds the valley on the south side; on the north side, the slope to the crest of Sierra Planchada is more gradual, rising only 200 or 300 m. above the valley. Water is relatively scarce in the district, and there are no running streams. The rainy season, usually beginning at the middle of June, lasts through July, and occasionally into August or September. In some years the rains fail entirely. The slope of the ground is such that nearly all the water immediately runs off. The arroyos along the flanks of the mountains are not very deep, but in heavy rains, sometimes approaching cloudbursts, a tremendous volume of water rushes down them, carrying large boulders. A certain amount of seepage collects in the agglomerate, lying below the conglomerate, and is retained in the local fractures. Some shallow wells have been sunk in this agglomerate, and one well over 150 m. deep was sunk on the Volcan ranch, supplying about 76 1. (20 gal.) per min. A considerable supply of water is collected in large earth reservoirs in and below the town of Esmeralda. In ordinary years this supply will last until January or February, after which the Volcan well has to be depended on until the next rainy season. Vegetation is scarce, aside from scanty scrub oak and other brush in the mountains, and a few mezquite, locust, pepper, and cottonwood trees

Jan 1, 1923

By J. Wes Blakely

In the mid-1950s the importation of foreign oil began to encroach on traditional coal markets such as railroad steam engine fuel, home heating, electrical generating plants, and others. Many of the smaller coal companies with substantial coal reserves subsequently found that they could no longer continue to mine economically and merged in various ways with larger established coal mining concerns. As the seats of top management and authority were removed from the mines to large metro centers such as New York, Pittsburgh, and Chicago, the more personal relationship between mine workers and management that had existed prior to these mergers began to be eroded and replaced by "remote control" mine management. The disappearance of this face-to-face contact of upper management with mine employees tended to create barriers blocking simple effective communications between coal mine management and labor. In examining the human relations aspects of the coal mining industry, many elements, some concerned with work and others not, have depicted the industry as almost devoid of good applied human relations and communications practices, and, in truth, little has been done to alleviate this situation. In past years many coal producing companies, with the exception of one of the largest, failed to adequately define the term "communications &apos; as it applied to their companies, whether internally or externally. Internally many still place heavy reliance on written communications such as company-wide newspapers to do the job of communicating with their employees which they feel ought to be done. One company puts an inordinate belief in its company "newspaper" as the primary instrument to stimulate its work force into increasing productivity. Primarily aimed at the workers, who greatly outnumber the salaried administrative people, this publication mainly documents the fortunes of individual mine workers who are felt to have achieved something with their lives, e.g., a mine worker who had managed to put four children through universities, the

Jan 1, 1981

By W. M. McKewan, R. G. Olsson

In order to improve the understanding of the iron oxide reduction mechanism, the rate of equal molar diffusion of hydrogen and water vapor was measured through disks of porous iron and alumina. The measuretneizts were made at atmospheric pressure at 800°, 900- , and 1000°C. It is shown tint the reduction of dense hematite pellets with hydrogen at these temperatures and at atmospheric pressure is to a great extent limited by gaseous diffusion between the bulk-gas phase and the iron-wustile interface. THE investigation of the reduction of iron oxides with hydrogen has been the subject of numerous papers. Although the effects of temperature, pressure, and gas composition on the rate of iron oxide reduction have been studied, the actual mechanism of the reduction process has not been definitely determined. As a means of improving the understanding of the mechanism, the rate of equal molar counterdiffusion of hydrogen and water vapor was measured through porous iron and porous alumina disks at reduction temperatures. The alumina was used as a basis of compari-son because its pore structure is homogeneous and independent of temperature. The porous iron was prepared by the reduction of dense hematite disks with hydrogen at the temperature of the subsequent diffusion experiment. The hematite disks were made from pellets that were identical to those used by McKewan1,2 in his study of iron oxide reduction with hydrogen. In these investigations the weight loss and rate of movement of the various interfaces were measured as a function of the reduction temperature and gas composition. With these reduction data and the presently reported diffusion data it is possible to determine the importance of H2-H2O transport between the bulk-gas phase and the Fe/FeO interface to the reduction of dense hematite. APPARATUS AND PROCEDURE A porous iron or alumina sample was held in the base plate of a sealed canister containing porous granular wustite, as illustrated schematically in Fig. 1. The canister was suspended from an automatic recording balance in a vertical tube furnace through which flowed hydrogen and water-vapor mixtures of known composition at atmospheric pressure (0.96 atm). Hydrogen from the gas stream diffused through the porous sample, reducing the wustite in the interior of the canister. The water vapor that was formed diffused back to the gas stream. The rate of diffusion was determined from the recorded weightloss data. The furnace, automatic balance, and gas-metering equipment have been described previously.2 The main body of the canister and the tubing extension were made of stainless steel while the base plate was made of high-purity iron. The main body of the canister was % in. in diam. It held approximately 6 g of porous granular wustite that was prepared by reducing 0.1- to 0.2-cm-diam specular hematite particles at 900°C with an H2-H2O mixture of a composition near the iron-wustite equilibrium value. The upper end of the 1/8-in.-diam tubing extension was sealed with a segment of plastic tubing and a tubing clamp. The temperature at the top of the furnace was sufficiently high so that no water vapor condensed inside the extension. In the experiments with porous iron, iron oxide samples were prepared from reagent-grade hematite that was pressed and sintered in a manner previously described.&apos; The resulting pellets had a density of 5.15 ± 0.05 g per cu cm. Each pellet was centerless-ground

Jan 1, 1967

By B. D. Cullity, K. S. Sree Harsha

When a copper or aluminum single crystal is swaged into wire, the resulting deformation texture depends on the original orientation of the crystal. The<100> and <111>orientations me essentially stable, while <110> is unstable. The greater the <100> content of the deformation texture, the stronger the wire is in torsion. the greater the<111>content, the stvonger it is in tenszotz. The preferred orientation (texture) of fcc wires, either after deformation or recrystallization, is usually a double fiber texture in which some grains have <100> parallel to the wire axis and others have <111>. The relative amounts of these two texture components, as reported by different investigators for the same metal, vary considerably. Previous work in this laboratory&apos; has shown that the starting texture of a wire, i.e., the texture which it has before deformation, can have a decided influence on the texture produced by deformation. In particular, it was found that the deformation texture of copper wire is essentially a single <100> texture, if the wire before deformation contains only a <100> component. This is true even when the deformation is carried to more than 98 pct reduction in area. This paper reports on further studies of the role played by the starting texture. Copper and aluminum single crystals of various orientations have been cold swaged into wire, and quantitative measurements of the resulting deformation textures have been made. The tensile and torsional properties of the deformed wires have also been measured, and the relation between these properties has been correlated with the texture of the wire. These measurements were made in order to demonstrate that a cold-worked wire can be made relatively strong in torsion and weak in tension, or vice versa, by proper selection of the texture before deformation. MATERIALS The copper was of the tough-pitch variety, containing, by weight, 99.962 pct Cu, 0.003 pct Fe, 0.025 pct 0, and 0.0021 pct Si. The aluminum contained more than 99.99 pct .&apos;41; the only reported impurities were 0.001 pct Fe, 0.001 pct Si, and 0.003 pct Zn, by weight. Large single crystals of these metals were grown by the Bridgman method in graphite crucibles and a helium atmospliere. Cylindrical specimens of predetermined orientation, about 1.5 in. long and 0.36 in. in diameter, were machined from the as-grown crystals and then etched to 0.25 in. to remove the effects of machining. Their orientations were checked by back-reflection Laue photographs, and they were then swaged to a diameter of 0.050 in. (96 pct reduction in area). 111 order to study the "inside texture" of the deformed wires, they were etched, after swaging, to a diameter of 0.040 in. before the texture measurements were made. TEXTURE MEASUREMENTS The fiber texture which exists in wire or rod can be represented by a curve showing the relation between the pole density I, for some selected crystal-lographic plane, and the angle $ between the pole of that plane and the wire axis (fiber axis). Such a curve will show maxima at particular values of , and these values disclose the texture components which are present. The relative amounts of these components can be determined2&apos;3 from the areas under the maxima on a curve of I sin F vs F. It is seldom necesszlry to measure I over the whole range of F from 0 to 90 deg, since the existence of maxima in the low-F relgion can be inferred from measurements confined to the high-F region. The X-ray measurements were made with a General Electric XRD-5 diffractometer and filtered copper radiation, according to one or the other of the following procedures: 1) A method developed in this laboratory,4 involving diffraction from a single piece of wire. 2) A modification of the Field and Merchant method.5 This method was originally devised for the examination of sheet specimens, but it can easily be adapted to the measurement of fiber texture. Three or four short lengths of wire are held in grooves machined in the flat face of a special lucite specimen holder. The axes of the wires are parallel to the plane defined by the incident and diffracted X-ray beams, and the holder to which the wires are attached can be rotated step-wise about the diffractometer axis for measurements at various angles 9.

Jan 1, 1962

By Harry A. Wahl

Precent fracture design procedures are bared on the total fracture area created. A method to distinguish beI,,.ecn total area and [he propped or effective fracture area has not been available. This paper presents a solution to this problem, applicable to horizontal fractures. The difierences between effective fracture area and torn] area are demonstrared in example calculations. This work is hayed on experimentally determined transport efficiencier of solids in sand-liquid slurries. Newtonian and non-Ne~vtoninn systems are considered. INTRODUCTION Fifteen years after commercial introduction, hydraulic fracturing remains the most successful stimulation technique in the oil field. This success is primarily due to ability of induced fractures to penetrate and alter permeabilities deep within formations. Many fields producing today could not have been developed without the hydraulic fracturing process. Because of wide usage, fracture-treatment design has received a great deal of engineering and research effort. This work, resulting in improved equipment and materials, has increased the benefits from fracture treatments as well as the applicability of the process. A major contribution was the development of fluid-loss additives. Necessarily, the number of parameters to be considered in treatment design has steadily increased, resulting in more complicated design techniques. Almost all present design procedures are based on the precepts set forth by Howard and Fast. Relating the fluid volume lost into the formation, the volume required in extending the fracture, and the total slurry volume injected, they developed an expression for the total fracture area created in terms of pertinent treatment parameters. Fluid loss during treatment was expressed as a function of time for three flow mechanisms. Although modifications of fluid loss equations have been made, the total fracture area concept has remained unaltered. A vast amount of field data indicate that induced fractures must be propped and held open to be effective. A notable exception is the Mesa Verde formation in the San Juan basin. However, analysis of these treatments shows that improved well productivities are obtained when propping agents are incorporated in the treating fluid. Although propped fracture area has been recognized as an important design parameter, a method to distinguish between total area and effective fracture area has not been available. The necessary information on slurry-sand transport in fractures has been lacking. Interest in the propped region of induced fractures is not restricted to areal extent alone. The distribution of sand within fractures is important from the standpoint of fracture flow capacities. Flow capacity affects the increase in well productivity after stimulation. The work of Huitt and Darin4 hows that partial monolayers of sand have large flow capacities compared to thick* dense sand packs. It has been postulated that gelled fluids have the ability to transport sand within the fractures at the deired low concentrations. An early contribution in the area of sand placement in fractures was made by Kern et al.&apos; They studied sand movement in a transparent vertical fracture model. It was observed that the sand tended to settle out in the bottom of the model before moving very far. When the fluid velocity exceeded a certain critical value, all of the sand injected began moving through the crack even though it settled to the bottom. This critical velocity was determined under several flow conditions. Some work on sand movement in horizontal fractures has been reported in Russian publications. Sand movement was studied by Izyumova and Shan&apos;gin&apos; using a transparent "pie-shaped" flow model to simulate a horizontal radial flow system. However, the data were limited, especially in a quantitative sense. Dorozhkin, Zheltov and Zheltow studied the behavior of sand-liquid slurries in a horizontal linear flow model. The quantitative data were restricted primarily to the thickness of sand deposits formed at the bottom of the fracture. An earlier paper provided basic data on the flow of sand in horizontal fractures. This study was designed to yield specific quantitative information on rate of advance of sand particles and pressure behavior under various flow conditions. A comprehensive photographic study was undertaken in a 10-ft windowed flow cell to provide the necessary qualitative and quantitative data. Since the number of potential variables far exceeded the capacity of the initial study, emphasis was placed on the effects of sand concentration, oil viscosity and oil flow rate. A detailed description of these experiments and the results are described in Ref. 9. However. the implications of this work on the fracture design calculations were not discussed. An analysis of these data as well as new data is provided in the following sections. EXPERIMENTAL RESULTS The primary objective of the experimental investigation was to provide information on the rate of advance of the solids in sand-liquid sturries. A 10%-ft long transparent

Jan 1, 1966

By Willis Burns

I. INTRODUCTION. These notes are submitted, not as a discussion of the modern practice of electrolytic-copper refining, but as the record of a refinery that was among the pioneers in the field and that is to-day, and has been for 17 years, operating under conditions not to be found in any similar plant in the country. I refer to the current density, which is at least 60 per cent. higher than that regularly employed elsewhere, and to the fact that the anodes treated are the direct product of the converter rather than of the reverberatory furnace. The writer has no knowledge of any other refinery treating anodes of this character.

Jan 8, 1913

Jan 1, 1956

By Truman H. Aldrich

The red, or fossiliferous, ore is found in the Clinton group of the Silurian formation. This group is from 100 to 500 ft. thick in Alabama, and its outcrops have been mapped by the State or the U. S. Geological Survey. In some places, it is entirely missing (doubtless islands in the Silurian Sea). In Etowah County, in part of Greasy Cove and vicinity, the upper seam is a coral reef impregnated with the red ore; in this same county, step faults bring up the ore in three or four practically parallel ridges. In Blount County and on Raccoon Mountain, the ore runs under the carboniferous rocks and outcrops in the valleys. When examining the logs of holes drilled for oil, wherever the drill has gone deep enough, the writer has found the Clinton group underlying the Warrior coal field. The following records of holes drilled primarily for oil, given in Bull. No. 22, Geological Survey of Alabama, show the presence of either ore or red rock, and suggest vast resources yet to be outlined and developed for ore in the future. The locations are given by number on the map. Hole No. 1 was drilled 6 miles southeast of Russellville, Franklin County, by the Woodward Oil & Gas Co. It passed through 160 ft. of the Clinton, but only a small show of red ore was found at 1280-1400 ft. A test well, No. 2, drilled near Atwood, Franklin County, in sectioil 26, township 8, range 14, penetrated the Clinton at 1608 ft. and found 38 ft. of limy red rock, also 8 ft. of some blood red ending at 1820 ft., making 46 ft. of red rock in all. It is reported that some good ore was cut through but this work was done by a churn drill. At least 400 ft. of the formation was classified as Clinton. Well NO. 3, called Frankford Well, was bored by S. A. Hobson and associates in the northwest quarter of section 7, township 6, range 12, Franklin County. At 927 ft., it is supposed to have entered the Clinton; the log is as follows: Ft. Sandy limestone with reddish, high ferruginous argillaceous inclusions 10 Same growing more ferruginous................................ 18 Hematitic limestone......................................... 30 Same with slightly less iron.................................... 23 81

Jan 1, 1925

By Plato Malozemoff, A. M. Gaudin

IN modern practice the major portion of an ore is reduced to flotation size by fine grinding. As the result of grinding fine enough to liberate most of the minerals, a substantial portion (generally 5 to 15 per cent) of the ore is inadvertently reduced to a size much finer than that necessary for liberation. This portion of most flotation pulps is very refractory to recovery by flotation. A reduction of one-quarter or more in recovery in this range of extremely fine particles can be observed. The loss in metals caused by overgrinding is appreciable. That this loss is characteristic of very fine particles has been suspected for some time;(l)† however, it was definitely quantified only recently.(2) Definite reduction in float-ability with reduction in particle size beyond a critical size of maximum floatability can be accepted now as an established fact. Formulating the Hypothesis In looking for the cause of the ill behavior of the finest particles it may be well to consider the essential differences between fine and coarse particles. A difference that immediately comes to mind is their intrinsic difference in size and consequently in relative extent of surface. If one agrees that attachment of mineral particles to bubbles must follow direct encounter of particles with bubbles one is forced to conclude(3) that the probability of encounter between a mineral particle and a bubble varies directly as the size of the particle, provided the particle is small compared to the bubble. In other words, the finer the particle the poorer its chance of being recovered in a given time of flotation. There is an effect, implicit in this theory, which should overcome the effect of excessive fineness of the particles; namely, flocculation of the particles. The floccules can be conceived as being simply larger particles and therefore capable of becoming attached to bubbles. And, indeed, in all the cases in which a sulfide mineral of near-colloidal size was successfully floated the mineral (but not necessarily the gangue) was flocculated. Moreover, it was shown experimentally(4) that galena previously flocculated by inorganic flocculators and then added to gangue

Jan 1, 1935