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By G. D. Monk, W. C. Krumbein

The relation between permeability and the size parameters of unconsolidated sand is approached by considering sands as logarithmic frequency distributions having the basic parameters mean size and standard deviation. Sieve separates were mixed in accordance with the normal logarithmic probability law, so that the mean and standard deviation could be varied at will. Experiments were conducted in which one parameter was kept fixed and the other varied; in this manner the dependence of permeability on the individual parameters was evaluated. It was found that permeability can he expressed as the product of a power function of the mean size and an exponential function of the standard deviation. Earlier studies of the effect of size of particles on the permeability of uncon-solidated sand have shown that the permeability varies with the square of some average diameter. This was first pointed out by Hazenl in 1892 and verified by Slichter2 in 1898. Hazen's mean size was defined as the 10 percentile of the cumulative curve (i.e., size that is smaller than 90 pel cent of the distribution and larger than 10 per cent). Slichter's effective size, on the other hand, was found by Wilsey3,4 to agree with the 31 percentile. Fair and Hatch6 found that the geometric mean size of sieve separates yielded the same power function; Hulbert and Feben6 found that the permeability of sieve separates varied as the 1.89 power of the median diameter (i.e., the size associated with the 50 percentile of the cumulative curve). Relatively few studies included the effect of the "sorting" of the sediment on the permeability. It was recognized that the nature of the size distribution, in terms of the spread of the particles about the mean, affects the permeability, but no systematic investigations of this effect are known to the writers. Cloud7 demonstrated that the effect of the grain-size distribution on permeability is definitely measurable. In the present paper the authors investigate this relation analytically, and show that the effects of the size parameters on permeability may be predicted for at least a restricted set of conditions. Properties OF Sediments Recent investigations have shown that essentially all the geologically important characteristics of sediments may be expressed in terms of six measurable quanti-tities possessed by each clastic sedimentary particle. These attributes are: (I) size, (2) shape (sphericity), (3) roundness (angularity) , (4) mineralogical composition (density), (5) surface texture, (6) orientation. Each of these characteristics may be defined in several manners. Size may be expressed in terms of sieve mesh, settling velocity, volume, etc. Sphericity is a shape concept introduced by Wadell;8 it is essentially a measure of the ratio of the surface area of an equivalent sphere to the surface area of the particle. The same

Jan 1, 1943

By Charles C. Rodd

PRIOR to 1938, proration procedure in Kansas required the physical testing of wells in order to set up a basis for allocating production. Subsequently the use of liquid-level data and bottom-hole pressure data was authorized on certain types of wells as a basis for calculating well capacities, thereby permitting wells to be tested at low rates and with small volumes of production. This paper gives some attention to the equipment used for obtaining liquid-level data but in general it is devoted to the theoretical and physical factors involved in well testing by drawdown methods. These tests are divided into two classifications: (1) liquid-level data used directly to calculate capacities, and (2) liquid-level data and liquid-level measuring equipment used in connection with other data to determine bottom-hole pressure. Equations and calculations for both types of tests are shown. Well capacities calculated from fill-up data have not been used generally but offer a simple means of testing some wells. Theoretical factors and calculations for such tests are shown. IN the state of Kansas, proration laws required that the "ability of a well to produce" be given consideration in state allocation orders and for many years this was the only factor used in prorating the allowed oil. The "ability of a well to produce" was the quantity of oil that could be obtained from a well in a prescribed period, usually 24 hr. Early in the history of State-regulated proration, Kansas operators realized that, unless some restriction were placed upon equipment, the competition between producers to obtain large well "potentials" might result in a race to install the largest pumping equipment. Consequently, restrictions were placed upon the size of tubing and length of pump stroke that could be used in pumping wells during potential tests. Later, restrictions were placed also upon the size of tubing and chokes that could be used in flowing walls. Despite the restriction set-up, better pumping equipment was designed and installed, pumps were improved, and various devices were invoked to obtain high rates of production for short periods of time. By 1937 pumping cycles of forty to forty-five 54-in. strokes per minute were not uncommon, and numerous wells had produced at the rate of 3500 bbl. per day for short periods. Such production was far beyond any rate that could be long sustained. Equipment necessary to take "potentials" was several times larger than that needed for normal producing purposes, and repairs and replacements required by the high pumping speeds were excessive. Also, many operators were beginning to suspect that the high rates of production maintained during "potential" tests were conducive to early water encroachment. By 1938 large-scale physical testing of wells in Kansas ended, the use of the bottom-hole pressure gauge had become common, engineers and operators were becoming familiar with the term "productivity index," and bottom-hole pressure was being used as a factor in allocation in many areas. There were many drawbacks, however, to large-scale use of

Jan 1, 1942

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 W. D. Lowry

As most of the industrial activity of Oregon is centered in the Portland area, the foundries there consume the bulk of the foundry sand produced in Oregon. Although a number of the larger towns scattered throughout the state have gray-iron foundries, the sand used by most of them is of local origin: The yearly consumption of foundry sand of all types for the past few war years in Oregon is estimated to have been approximately 40,000 tons valued at about $285,000, of which an estimated 18,000 tons was shipped in from the Ottawa, Ill., district for use largely by the steel foundries. Until 1945 much of the silica sand consumed by the steel foundries in the Pacific Northwest, approximately 50,000 tons in 1944, came from Ottawa, Ill. and surrounding regions. Although some silica sand was shipped in from Belgium in the past, none is known to have been imported in recent years. Early in 1945, a very promising high-grade silica sand being produced near Eugene, Oregon, was introduced, and all but two of the Portland steel foundries are using this new sand. Until a few years ago, the search for good local (Oregon) foundry sands was carried on largely by the foundry supply houses. Recently the Oregon Department of Geology and Mineral Industries has investigated a number of deposits and has carried on and fostered research on the most promising deposit near Eugene, about 120 miles south of Portland. High-grade silica foundry sand from this deposit is now being marketed in Oregon, Washington, and British Columbia. The Eugene sand is one of the very few outstanding western steel-foundry sands. Field investigations by the Oregon Department show that there are relatively few deposits of sand in Oregon suitable for foundry use. A knowledge of the geology of the state makes this readily understandable. The only major primary sources of the quartz present in sandstones in Oregon are the intrusive masses of granite, granodiorite, and quartz diorite of late Jurassic or early Cretaceous age found in the Siskiyou Mountains of southwestetn Oregon, a part of the old Klamath Mountain highland, and in the Blue Mountains of northeastern Oregon. Transportation militates against the development of any possible deposits of foundry sand found east of the Cascade Mountains in central and eastern Oregon because few railroads traverse that area. East of the Cascades, which separate western from eastern Oregon, many of the older sediments of Paleozoic and Mesozoic age have either been metamorphosed or contain much volcanic eruptive material, and even if some of the Mesozoic sediments are highly quartzose in places, they are in relatively inaccessible areas. All the Tertiary sediments there are of continental origin and contain much ash and other volcanic debris, for there was great volcanic activity during much of that period. In western Oregon much the same is true of the Paleozoic and Mesozoic rocks

Jan 1, 1947

By C. E. Violet, R. J. Borg, E. M. Howard

The miscibility gap in the Au-Ni system has been determined by Mossbauer spectroscopy, with used as a probe. The phase boundaries were determined from the compositional dependence of both the isomer shift and Curie temperature. X-ray diffraction measurements were also used to confirm the Mossbauer results. 1 HE purpose of this research is to demonstrate the application of Mbssbauer spectroscopy to the determination of phase boundaries and to redetermine the miscibility gap by an independent and novel technique. The techniques evolved in this study are readily applicable to other polyphase systems and are generally as quick and accurate as the more conventional methods, e.g., metallography, X-ray diffraction, thermal analysis, and so forth. To be sure, not all polyphase systems will lend themselves favorably to Mijssbauer investigations, but this is a problem met in the use of conventional methods as well. The Mbssbauer spectrum responds to a different set of physical parameters, and consequently provides an entirely independent method of analysis. It is especially useful if the system has either a ferromagnetic or an antiferromagnetic transition. The Au-Ni system was selected because alloys containing more than -60 at. pct Ni become magnetically ordered at low temperatures; also the miscibility gap is quite well established (see Ref. 7 for a compilation of pertinent references, also Fig. 11, and thus provides a reliable test of this novel procedure. As Fe is the most commonly used Mijssbauer isotope, there exists a wealth of information concerning its behavior in iron-containing alloys and compounds. However, as yet there have been relatively few experiments using it as a probe to investigate nonferrous systems. By choosing a nonferrous alloy system, we are able to demonstrate that its use is not restricted to systems containing iron as one of the major constituents. Wertheim and ~ernick' have used the same method to investigate Cu-Ni, and demonstrated that one can obtain a systematic variation in the isomer shift and magnetic hyperfine field. However, we believe this to be the first time these techniques have been used to establish phase boundaries. Two hyperfine interactions were measured and used to determine the phase boundaries, viz., the magnetic hyperfine splitting and the isomer shift which in this alloy system are both strong functions of composition. Calibration curves were established based upon single-phase solid solutions obtained by quenching from temperatures well above the maximum of the miscibility gap, see Fig. 1. Solid solutions containing 25, 50, 65, 75, 85, 92, and 96 pct Ni as well as pure nickel were used in the calibration procedure. Fig. 2 shows the Curie temperature, TC, and the isomer shift, v,, as determined from the Mbssbauer spectra, and variation in lattice parameter as determined by X-ray diffraction, as functions of composition. The compositions of the two-phase systems quenched from temperatures within the miscibility gap are obtained by comparing their respective values of TC and v0 with the calibration data. I) EXPERIMENTAL Mbssbauer sources were made by fusing the component metals in a tungsten arc melter, which has a water-cooled copper hearth. Both nickel and gold were 99.999 pct pure, and the melting was done in an atmosphere of purified argon. The alloys were rolled, diced,

Jan 1, 1969

By Richard P. Schoemaker

INTRODUCTION IN underground mining operations the effects of economic and mechanical factors on costs and profits can readily be appreciated and can perhaps be expressed in exact figures and percentages. Less apparent, but frequently more important, is the influence of physical stress. Stress causes failure of supports, collapse of openings, rockbursts, and other damage which directly affects the costs of maintenance, and also to a certain extent the accident rate. Stress can, however, if properly directed, be an aid to mining operations. The caving methods in metal mining and the long-wall method in coal mining are well-known examples. In large-scale mining operations it is almost impossible to neglect stress-control. A better understanding of the mechanism of rock pressure and the application of its principles to practical mining will inevitably lead to a reduction in operating costs. Many theories have been advanced to give the mining engineer a practical outline for stress-control but, although today most experts agree upon the principles of stress distribution around underground openings, there is still no generally accepted theory that explains all phenomena. The main reasons for this incomplete understanding of the problem are the lack of accurate knowledge of the physical properties of rocks under field conditions, and the great complexity of these conditions due to inhomogeneity of the rock, stratification, tectonic disturbances, and many other unknown factors. The research on the rock pressure problems has, however, yielded some valuable facts which, expressed in practical terms, and adapted to local conditions, may become a valuable aid for mining operations. The purpose of this paper is to give a review of the most important accomplishments of this research with respect to the stress phenomena around small underground openings, such as tunnels and shafts, so as to arrive at an outline of the problem as it stands today. Special emphasis is placed on a new theory by the German mining engineer, Rudolf Fenner, which has never before been published or discussed in English. THE PRESSURE DOME THEORY The formation of a dome-shaped space around underground openings is well known from field observations. When openings are made in rock under stress, the rock in the top of the openings will often fail, and caving will continue until the openings have assumed a dome-shaped form, after which equilibrium apparently is re-established. The oldest theory which attempted to explain the phenomenon is the "beam" theory, which postulates that the hanging wall consists of stratified measures that behave as independent beams with fixed ends and a uniformly distributed load. When failure of the beam occurs, inward shearing at the ends will cause the formation of a dome-shaped space. The pressure dome theory, which more or less evolved from the beam theory, merely

Jan 1, 1947

By I. J. Lin, A. Mitzmager

This paper describes a series of experiments conducted to determine how the physicochemical properties of the suspending fluid affect the size reduction of quartz in a ball mill. Particular attention was directed toward the differences in rate of grinding and particle size distributions when either polar or non-polar fluids were the suspending liquids. Grinding was performed with water, carbon tetrachloride and methylcyclohexane as the liquids, and also in nitrogen for comparative purposes. From the results ob- tained, the authors have concluded that the presence of water greatly enhances efficiency in the grinding of quartz. Comminution is generally regarded as a purely physical process in which fragmentation of a solid is obtained by the application of suitable forces. In 1944, however, Rehbinder et al.1 pioneered the idea that the interfacial forces between the solid and the media plays an important role in comminution. Since then, a number of researches have shown conclusively that comminution is affected by surface chemical phenomena,2-5 and Gaudin went as far as to compare comminution to a chemical reaction.6 The effect of the viscosity and the density of the fluid media in grinding was also investigated, but

Jan 1, 1969

By A. T. Beckwith

THE Lehigh Navigation Coal Company Inc. operates steep-pitch, relatively deep mines in the Panther Creek Valley, at the eastern end of the southern anthracite coal field. Commercially minable coal beds are the Mammoth,† Primrose, Orchard, and Buck Mountain,‡ their respective thicknesses average 50, 15, 1o and 12 ft. Sand slates immediately overlie and underlie these beds, though in some locations sandstone or conglomerate beds occur. Underground operations extend to a depth of 1200 ft. below the surface, and comprise a bulk of virgin work on the lower levels, and a small amount of remining on the upper levels. With increase in depth, ventilation has become a more important factor. DEVELOPMENT In early days slopes or drifts were driven in the outcropping coal on the hillsides. Subsequent development was by water-level tunnels, with portals above high water in Panther Creek. These tunnels have been maintained because they intercept and drain much water that enters the mined-out portion of the bed and otherwise would follow down to the deep workings. Below these tunnels, the coal was customarily developed by slopes. Muleways, which are zigzag chutes easy to travel, were also driven to connect lower openings with the water levels. When it became necessary to go still deeper, the slopes were abandoned, and vertical multicompartment shafts were sunk from the surface. Levels have been at vertical intervals of from 195 to 250 ft. Recent practice has been toward the latter spacing; splitting the total lift, however, by starting to mine from chutes extending halfway up to the level above. Chutes customarily are spaced at 50, 60 or 70-ft. centers along the gangways. At some mines, additional shafts have been sunk from the surface to the level containing the main pumping station, and these carry the discharge lines from the pumps. As the mines are ventilated by the exhausting system, both the hoisting and so-called water shafts serve as intakes. The main fan is always on the surface, and is connected with the return airways from the various levels by an air hole or a vertical shaft. For economy, when the present deepest levels were developed, main return-air shafts or air holes were not extended to the new level, but connections were made from the new level to that above by two or more holes. It is doubtful that this method will be continued, as complications in the system, increased resistance to flow, and other difficulties undoubtedly will counterbalance any economies this provision may afford.

Jan 1, 1942

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 play a definite part in the spontaneous combustion of coal in the goaf (waste). Tables 1 and 2 contain the analyses of samples of dust collected from a mine and from a dust collector. Some idea of the degree of fineness of the particles of fusain may be obtained from a study of the analyses of the dust from the dust collector; 80 per cent. of the dust would pass through a 200-mesh screen while the fusain was concentrated in the finest dust. The material that passed through a 90-mesh screen contained 54 per cent. of fusain while that between a 30- and a 90-mesh only con-

Jan 1, 1925

By B. A. Cheadle, C. E. Ells

The ovienlalion of hexagonal a-zirconium crystals in cold-drawn Zircaloy-2 tubes and in both as-extruded and heat-treated Zr-2.5 wt pcl ND tubes has been rrleasured using the inverse Pole - figure technique. Uniaxial tensile tests hare shown the Zil-caloy-2 lubes to hare highly anisotropic delovmation behavior whereas heat-treated Zr-2.5 wt pet Nb tubes are nearly isotropic. The differences in deformation behavior are esbloilred from the observed textures of the tubes and the deformation systems known to oberate in Zircnloy,-3. Tlze vcsults lead to an explanation of the high effective strain observed fov the Zircaloy-2 tubes as colrzpared to heat-treated Zr-2.5 wt pet Nb tubes in restrained end burst tests at 280° to 300°C. THE Zr-2.5 wt pct Nb alloy. when heat-treated by quenching from temperatures slightly below the (a + p)/P phase boundary and subsequently aged at 500°C, has tensile strengths about 50 pct greater than those of 20 pct cold-worked Zircaloy-2.1 There is. therefore, considerable economic incentive to replace Zircaloy-2 with the heat-treated alloy in some in-reactor applications. notably for pressure tubes, where strength is a prime consideration. However, when tubes of Zr-2.5 wt pct Nb fabricated by extrusion and drawing prior to heat treatment were subjected to restrained end-burst tests at 300 °C. the circumferential expansion at failure1 was only 10 pct that of cold-drawn Zircaloy-2 tubes in similar tests,2 Table I. This result was not predicted from uniaxial tensile tests in which the ductilities of the two materials were quite similar.' The detailed requirement for ductility in pressure vessels has not yet been worked out. and comparison of the relative merits of cold-worked Zircaloy-2 and heat-treated Zr-2.5 wt pct Nb is further complicated by the irradiation-induced loss of ductility and hydrogen pickup each will undergo from reactor operation.1,2 Nevertheless. the lower circumferential expansion of the Zr-2.5 wt pct Nb tubes raised serious doubts on the advisability of their use as pressure vessels. For this reason, an investigation to determine the cause for different ductilities of the two types of tubes was initiated. From a study of uniaxial tensile properties and crystallographic orientation it has been found that the fracture ductilities observed in the burst tests can be related directly to the crystallographic ori-

Jan 1, 1965

By H. P. Schwede, H. G. Doll

This paper describes a method to provide identification of particular depths in a borehole through the use of radioactive markers. The correlation of a marker, placed in the wall of a borehole, with known points of the electrical log and with the casing collars in the cased hole permits accurate positioning of tools with respect to a formation, regardless of absolute depth. Such a process is particularly useful in gun perforation of a casing in a well. Technique and equipment are discussed and illustrated. Examples are given of practical application in the field. Introduction During the past decade the search for petroleum has increased the importance of testing zones at depths in wells which have become progressively deeper. The development of new techniques, such as electrical logging, has permitted the identification of producing formations which consist of comparatively thin strata. When thin beds are to be produced at great depths, the problem of positioning tools accurately to place the well in production becomes acute.l Continuous consideration is being given in the petroleum industry towards the improvement of depth measurements in a borehole. The accuracy in absolute depth measurements, whether made in an open or cased hole, whether determined by a cable or a drill pipe, depends upon a number of factors, such as tension, temperature, and calibration. For example, the effects of tension from the weight of 10,000 ft of drill pipe and the thermal expansion of this length . of pipe, where its average temperature has increased SO"', will Produce an elongation as much as 8 ft.2 The effects Of such factors can be minimized through the use of care in depth measurements, the application of corrections based on experience, and continuous calibration or checking. The fact that different methods and different tools are used to determine the depths of formations in wells will sometimes give rise to a difference between measurements. It is evident that an important requirement in a well is the ability to locate at will any subsurface point. While absolute depth measurements have ion in recent years, it is reassuring to have other means to verify, for example, that a casing is perforated at a particular place with reference to a zone within a formation. Such a check on measurements may be had by placing a reference marker at a point known with respect to the electrical log of the borehole. That point is usually chosen to be in proximity to the 'One to be perforated. Thus, only short in depth measurements are made and any inaccuracy becomes very small and of minor importance' The use of reference markers located at fixed points predetermined in each zone where future operations are contemplated enables the operator to position any tool

Jan 1, 1948

By S. H. Lorain, Norman L. Wimmler, S. Ricker, P. E. Oscarson, H. G. Iverson

This paper has been prepared with the principal objective of recording the results of the Bureau of Mines exploration of five major clay deposits in the Western Region. It is based mainly on data contained in unpublished Bureau of Mines reports. Acknowledgment is made to the Federal Geological Survey for its cooperative work with the Bureau of Mines, to the various State geological and mining departments, and other State and local agencies. Clay Exploration by the Bureau of Mines Much has been written and published on clays and clay deposits relating to their refractory, ceramic, and other qualities but such literature is lacking in analyses of the available alumina content of the clays and provides little indication of their possibilities as a source of alumina. With this new objective in view, a great many of the known clay deposits were reexamined and new ones discovered. The Bureau of Mines made preliminary examination of numerous areas in the western United States. Five of those most favorably indicated were systematically drilled, and in each a large amount of high-alumina clay has been found. These five major projects are Molalla and Hobart Butte, in western Oregon; Cowlitz-Castle Rock, in southwestern Washington; Ione, in California; and the Olson-Troy area in Idaho (Fig. I). Preliminary scout drilling was done in the Stockton deposit at Coeur d'Alene, Idaho; the White ware deposit near Lewis-town, Mont.; and 13 areas in the Spokane or eastern Washington region, where the most favorably indicated area, known as the Excelsior, is now being drilled more systematically. Preliminary drilling was undertaken in numerous areas adjacent to the major deposits and others more remote. As a result, large additional clay possibilities were found. The Clay Deposits The clay deposits under consideration are of the sedimentary or transported types, parts of which have been altered further by the agencies of weathering, ground water, or hydrothermal action. There are extensive deposits of residual clays in northern Idaho and in eastern Washington, but they have been found to be low in the available alumina and to contain much free quartz, mica, and unaltered feldspar. To be of value, they must first be subjected to beneficiation to remove these gangue minerals. The sedimentary clays have been derived largely from the decomposition, erosion, and transportation of granites, gneisses, schists, and basalts. At Molalla, some

Jan 1, 1948

By G. Sachs, Jr. Brown W. F., Ebert L. J.

It is a generally recognized fact that a steel quenched from the austenitic range and tempered to yield a structure composed of tempered martensite becomes increasingly more ductile with increasing tempering temperature. However, the conventional tensile test fails to yield any value that is sensitive to differences in behavior on tempering among the various low-alloy steels or among different heats of a particular steel. The notched impact bending test, on the other hand, has been recognized for a considerable length of time as capable of revealing differences in impact properties among various steels tempered to 'the same strength level (i.e., the same tensile strength in a conventional tensile test). However, this test is very complex and its significance has not been clarified up to the present time. Of its three characteristic features—the high speed, the notch, and the bending—the notch has been found by Davidenkov2 to be the most potent embrittling factor. Recent investigations on low-alloy steels have shown static notch-bar tensile tests to be more lucid and to evaluate the metal properties in much the same manner as impact tests. In an attempt to analyze the fundamental nature of this test, it was found possible to separate the effects of the two basic characteristics of the stress pattern introduced by the presence of a circumferential notch, the stress state and the high initial stress concentration at the notch bottom. The major conclusions drawn from these previous investigations were as follows: I. The magnitude of the triaxiality at fracture depends primarily on the initial notch depth. Its effect is a great reduction in the average ductility (contraction in area at fracture in the notched section) as compared with that observed in uniaxial tension. This triaxial stress state occurs at a point in the interior of the notch specimen. It determines the notch ductility if the notch is mild and/or the metal possesses a considerable ductility. On the contrary, brittle specimens probably fracture on the metal surface (at the notch bottom) at which point biaxial stress state is present. This biaxiality also considerably reduces the ductility of the metal. For small notch ductilities the notch strength and the notch ductility become very sensitive to embrittling factors. This is contrary to the behavior. of the ductility values derived from a conventional tensile test, which are comparatively insensitive.

Jan 1, 1947

By E. N. Cameron, H. M. Bannerman

During the years 1942-1934, about 125 New England deposits were mined for sheet and punch mica, and many others were briefly prospected. During this period the Geological Survey, United States Department of the Interior, carried on detailcd studies of the deposits and the pegmatite bodies that contain them. The primary purpose of the studies was to provide geological information that would contribute toward efficient mine development and operation. The studies were aimed directly at practical production problems. Detailed maps showing the structure of the deposits were prepared, and geological findings were closely correlated with data on specific yields and costs of mining and processing. The result is information that permits a reasonably accurate appraisal of the mica deposits of New England and the mining industry that they support. At a time when the future of the industry is in doubt, it seems desirable to submit this appraisal for consideration. Domestic mica deposits supply only a small fraction of the country's needs in normal times? for only the richest domestic deposits can compete with the low-cost mines of India and Brazil. However, the possibility that this country may be cut off from its supplies in time of war gives domestic deposits an importance much greater than their peacetime production would imply. New England supplied about 22 per cent of domestic output in 1943 and 1944, the peak years of wartime production. Its actual contribution to the war effort was greater, for the proportion of sheet mica of high quality in the New England product is higher than the average for domestic mica. The data analyzed below were collected for the Geological Survey by D. M. Larra-bee, A. H. McNair, J. J. Page, V. E. Shai-nin, G. W. Stewart, and the co-authors of this paper. The cooperation of officials of Colonial Mica Corporation and of mine operators and owners in furnishing information is gratefully acknowledged. D. M. Larrabee, A. H. McNair, and V. E. Shainin have made various suggestions based on critical reading of the manuscript. Analysis oF Warrtime Operations In considering the data presented in this report, it must be remembered that the scale of mica operations is very small compared with that of many other mining industries. The typical New England mica mine of 1943 and 1944 was worked by a crew of five or six men. Equipment was varied but on the whole extremely simple. The first stage of operation at a deposit was normally opencut mining. Drilling was done mostly with jackhammers powered by portable compressors driven by gasoline engines. Muck was shoveled by hand into buckets with a capacity of 45 to 35 ton and commonly hoisted by derrick to a dump adjacent to the cut. As operations were carried to greater depth, and the tram sition to underground mining was made, these methods were modified to a degree depending largely on the attitude of the deposit mined. At steeply dipping deposits,

Jan 1, 1948

By M. K. Geer, H. F. Yancey

Investigations of the fundamental factors involved in the performance of various coal-cleaning processes have constituted a substantial portion of the research 011 coal cleaning conducted by the Bureau of Mines. These detailed studies of the mechanism of separating coal from impurity in various cleaning devices were undertaken to provide the coal industry with information that is helpful in selecting the type of cleaner most suitable for treating a particular coal. Previous reports describing these investigations have dealt with the wet table,1 the pneumatic table,' and the plunger,3 pulsator.4 and Baum types5 of jigs. The present report compares the performance of three commonly used units treating the same coal—a pneumatic jig, also known as the air-flow. cleaner, a pneumatic table, and a Baum-type jig. Object and Plan The fact that pneumatic coal-cleaning processes are less efficient than wet-washing methods because they are unable to make as sharp a separation between coal and impurity is well recogilized. The literature, however, contains little quantitative in- formation on the relative performances of the two types of cleaners. The object of the present report is to present a detailed comparison of the performances of two pneumatic units and one wet-washing process treating coal from the same bed. Although the information in this report demonstrates that the performance of the pneumatic cleaners is not as good as that of those employing water, it must not be construed as reflecting on the usefullless of such equipment. Performance is often secondary to other factors in the selection of coal-cleaning equipment, and the advantages inherent in pneumatic processes frequently outweigh the limitations imposed by their performance. Specific gravity and particle size are the principal factors that influence the separation of coal from impurity in either pneumatic or wet processes; consequently, the tools available for this investigation were the float-and-sink bath and the screen. Accordingly, the raw coal, clean coal, and refuse samples representing the operation of each type of cleaning unit were first separated into a series of density fractions by means of the float-and-sink bath, and then each density fraction was screened into a series of size fractions. By this procedure the raw coal, clean coal, and refuse were subdivided into components of restricted ranges in density and size. From these data it was possible to determine how the cleaning unit disposed of each component of the raw coal; that is. what proportion of each component is sent to clean coal or rejected as refuse.

Jan 1, 1947

By H. F. Mills

The Iron King mine is I2 miles east of Prescott Arizona, in low foothills of the Agua Fria mining district. It was operated in 1906 and 1907, using gravity methods of concentration, mostly on oxide ores. In 1923 and 1924 shipments of sulphide ores were made to the Humboldt smelter. It remained inactive and stripped unti1 1936, when it was unwatered and sampled to the 400-ft level, the bottom at that time. In 1937 the Iron King Mining Co. purchased the mine and shipped oxide ores. During 1938 a bulk flotation plant of I40 tons daily capacity was erected. The mill has been enlarged and operations have been continuous since the mill first started. In July 1942, the Shattuck Denn Mining Corporation purchased the physical assets from the Iron King Mining Co., and since that time it has operated as the Iron King Branch of the Shattuck Dcnn Mining Corporation. Economic metals recovered are gold, zinc, silver, lead, a little copper, and fluxing pyrite. The ore occurs as a series of northward-dipping shoots arranged in echelon pattern, the series extending over a length of 3500 ft. Strike lengths of shoots vary from 60 to 600 ft, and widths from 3 ft to as much as 14 ft. The ore occurs in a sheared zone in pre-Cambrian chloritic schist. This schist belt is about 6 miles wide, and the ore zone is about 4 miles from the pre-Cambrian granites to the west. No intrusive rocks have been found in the mine, nor is there evidence of any on surface that might indicate a genetic connection with the ore occurrence (Fig I). The schists strike N23°E and dip 75° to the northwest, which might indicate an overturned thrusting from the granites. In the upper levels, the echelon pattern in which the ore occurs was quite regular. no disturbance of the enclosing schist, or of any faulting that might contribute to the formation of the ore pattern was noted. There is a possibility that the ore zone may be on the axis of an isoclinal fold. Another interesting feature is the more or less typical zoning of minerals along the strike in each of the ore shoots (Fig 2). The north end of each shoot is enclosed by schist, while the south ends usually extend out at full width beyond the economic mining limits in a pyrite-quartz low-grade material. The plane of demarcation between ore and schist is very sharp, with little or no impregnation of sulphide in the schist, especially on the footwall side. The footwall schists are usually firm and strong, and vary from dioritic phases to fine-grained, lighter colored bands, almost silky in texture. The hanging wall for a width of 50 to 80 ft consists of alternating sheetings of chloritic and pyritic schists. The mine is now partly developed to the 920-ft level, with some diamond drilling from the 1150-ft station of No. 6 shaft. Economically there has been little change in nature or grade of ore from the top of the sulphides, about 200 ft below surface, to the bottom levels. There have been a few echelons in depth, just as there are in plan, and while a few shoots have had

Jan 1, 1949

By W. T. Bishop, G. A. Crowe

While the literature in the United States on general polarographic technique is extensive, very little appears to be directly applicable to the analysis of flotation tailings. For this reason, it seemed worth while to present a few polarographic methods of ore analysis that have been in constant use in the laboratories of the Hercules Experiment Station for the past few years. At the time of our initial investigation of the polarographic method, there was little or no mention of its specific application to flotation tailings. It was therefore necessary for us to establish suitable conditions for the analysis of our flotation tailings and to consider possible interfering constituents. The polarograph, or dropping mercury electrode, method was discovered in 1925 by J. Heyrovsky and M. Shikata,1 of the Charles University, Prague. This method has since received extensive development and the literature contains many articles on the use of the polarograph for the quantitative determination of metals as well as anions, oxygen in solution, and reducible organic compounds. Kolthoff and Lingane,² by the publication of their book, "Polarography," in 1941 did much to advance the knowledge and use of the polarograph. In chapter 25 of that book, methods for the polarographic analysis of brass, steel and iron products, alloys, and zinc ore are given. Aluminum,³ cadmium,³,4 cobalt,4 cop-per,³-9 gold,10 iron,3,11 lead,³,l2,l³ molybdenum,14 nickel,4,8,9 tin," and zinc³,4,5,7 in ores have been analyzed by the polarograph. However, most of the work on tailing samples has been published in Russian journals and translations are not yet readily available. In this paper we will describe the method that was developed and used in our laboratory for the determination of copper, zinc, and lead in flotation tailings. Principle OF the Method The polarograph is an instrument for applying a potential to a mercury pool and a dropping mercury electrode separated by a solution, and for measuring the resultant electrical current. The procedure is essentially a small-scale electrolysis, in which the voltage required to reduce or oxidize the material identifies it qualitatively and the current measures the concentration quantitatively. Different constituents in a sample may often be determined simultaneously provided they reduce at sufficiently different voltages. An example is the determination of copper and zinc in the same solution. The reduction potentials are quite far apart, as shown in Fig. I. The polarographic method is particularly useful in the range of concentration between those normally determined by spectographic and chemical methods. In

Jan 1, 1947

By E. H. Rose

The present symposium on flotation machines provides a unique opportunity for group reappraisal of standard or habitual viewpoints. A symposium is by definition a trading post- for observations that might prove complementary when put together, thus leading to useful thoughts that might not have been evident from the original observations individually. The present paper, pertaining to power consumption in flotation, is deliberately an experiment of that kind. Data were solicited from the operating superintendents of several of the major flotation plants on this continent. The information received, covering a total of 14 separate operations in seven plants, has been collated in terms of power intensity; that is, the total power input per cubic foot of cell volume. This departs somewhat from the conventional expression of power per ton of ore treated, though the latter figure is also given for the plants concerned. Because of wartime restrictions, particularly in Canada, identifying names of plants and machines are withheld. Not as a firm conclusion, but as a tender for symposium discussion, the following points are made: 1. That flotation is a power operation in much the same sense as ball milling. 2. That contact time is the complement of power intensity and may be decreased as the latter is increased. 3. That a decrease in flotation power per ton of ore can result from an increase in power intensity. Analogy with Grinding In grinding, it has become axiomatic that the more the power put into a given operation, the greater the work performance. The analogous view is now proposed that the effectiveness of any flotation operation will be related to the mechanical energy usefully applied to that operation. Under this view, each increment of properly directed input energy should give either an increase in unit tonnage or an improvement in the metallurgical separation (concentrate grade or tailing grade), until either the theoretical limit imposed by mineral constitution or surface condition is reached, or until further increments of power become uneconomic under the law of diminishing returns. Thus, as in grinding, there are two forms of output that greater power input or improved utilization of power can produce. As for the law of diminishing returns, lower unit cost of power through improved generating efficiency in the past decade has pushed the limit back. Over and above this, however, there is strong indication in the operationg data herein presented that higher power intensity results in an actual economy of over-all power consumption. Like crushing and grinding, flotation accomplishes a rupture of the forces of molecular attraction, by taking particles from the common environment and placing them in the two separate environments of

Jan 1, 1947

By W. M. Mobley

The coal industry in Alabama, centered in Birmingham, has pioneered coal-bene-ficiation practice in the United States. The nature of the coal seams and mining methods employed have necessitated use of equipment and methods best adapted to the local conditions. Although all of the 30 or more coal seams now being mined in the state receive beneficiation, only the three most important producers of coking coals, the Pratt, Mary Lee and Black Creek, are discussed in detail. Nature of the seams, washability characteristics and equipment used are given as examples of the extent of work and progress in this field. The coal seams in Alabama are relatively thin and pitching, making mining difficult and expensive. Most of them are characterized by thin partings of rock or shale in the seam itself, as well as laminations of bone and rash. Mechanical mining methods have increased the occlusions from roof and floor to such an extent that nearly all the coal mined in the state must receive some treatment before it can be put on the market. During the year ending Sept. 30, 1943,1 18,129,792 tons of coal were mined in the state and 14,364,177 tons, or 79.2 per cent, received treatment. Excluding from the total the 1,223,014 tons produced by small wagon mines and the hand-picked lump coal, the amount re- ceiving beneficiation would be more than 90.00 per cent. This is, by far, greater than in any other coal-producing state. The earliest record of coal beneficiation in Alabama was the installation in 1890 of an experimental rig washer by Alexander Cunningham, for the Sloss Iron and Steel Co. at its blast furnace in Birmingham.* In 1894 the Jeffrey Manufacturing Co. introduced the English Robinson washer, a combination of a hydraulic classifier and centrifugal machine. Erskine Ramsay, who has contributed so much to the coal industry, saw its possibilities as well as its mechanical defects and soon had his inventive mind at work. He added a sludge tank of his own design, and many Robinson-Ramsay washers were installed in Alabama and other states. The Stewart jig appeared in 1900, followed by the Montgomery jig in 1910 and both have found extensive use. Increased interest in this field led to new designs, such as the American, Elmore, Burke and Faust. The first Baum-type Norton jig was operated in 1930 and within the last five years six large installations of this type have been made by the McNally-Pitts-burg, Jeffrey and Link-Belt Companies. Wet-washing tables were introduced in 1922 but not extensively used until recently. The two most popular types are the Deister-Overstrom and Deister Plat-O. The coal-cleaning equipment used in Alabama has been relatively simple, yet efficient, but as the amount of impurities in the raw coal has been increased by mechanical mining and labor costs have become higher, much interest has been shown in sand cones, froth flotation and

Jan 1, 1947

By I. J. Logan, Warren L. Baker

By 1950 or soon thereafter facilities will be available in foreign countries for the production, transportation, and refining of about 4,305,000 bbl per day of crude oil—a volume not far short of current United States output. This is indicated by announced plans for foreign expansion, - some of the work being already under way. The projected potential production is about 1,500,000 bbl per day or 50 pct above the record-setting foreign production of 2,810,000 bbl daily in 1946. The scheduled new foreign facilities are equivalent to almost one third of the present facilities of the United States. Fears that so much additional foreign oil may flood world markets and disrupt the domestic industry of the United States are not justified. The projected foreign expansion apparently has been planned on a sound business basis, with careful consideration of the world's actual need for all the projected additional production. Materially increased world demand for petroleum promises to absorb the increased supplies without ill effect upon the domestic industry. Even by applying conservative estimates of both foreign and domestic demand, it is indicated that world requirements can absorb the projected larger foreign output and still permit continued increase in United States production. World demand would have to increase only 5.7 pct per year in the 1947 to 1950 period to absorb the prospective supply. Such an increase may be conservatively projected, in view of past and current trends. Introduction Recent announcements of plans for expanding petroleum facilities in the Middle East and Venezuela foreshadow an unusually sharp increase in foreign production in the immediate future. Therefore, the next few years will bring far-reaching changes in world petroleum affairs, with foreign petroleum production and other activities assuming much greater importance than formerly. Tabulation of figures on development already under way or planned indicates that in the next several years facilities will be available for producing, transporting and refining twice the prewar production of foreign fields and about 50 pct or nearly 1,500,000 bbl a day above their record-level output of 1946. To say that foreign fields may be producing such an enlarged quantity by 1950 is, of course, a statement of great significance to everyone connected .with the oil industry and especially to those of the American petroleum industry. A production of 1,500,000 bbl daily is equal to the combined yield of the states of Oklahoma, Kansas, Illinois, Louisiana, Arkansas, Mississippi and New Mexico. This means that within the next several years foreign petroleum facilities will undergo a new expansion equivalent to one third of the present facilities of the United States. To think of such an expansion in foreign production is to raise at this meeting the question of what this prospective foreign development means for the United States, the American petroleum industry in general, and the American engineer and technologist in particular. It is only logical to question whether or

Jan 1, 1948