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By H. B. C. Nitze

In view of the extensive use of vanning-machines in this country, a brief comparison of the results obtained by the plain belt generally employed, and the corrugated belt which was introduced a few years ago, may be of interest. The data given below have been abstracted from a working-journal, and hence lack the precision, and also, in several desirable particulars, the detail, which would naturally have been secured in special experiments ; but they have the advantage of being working-figures, and are sufficient as the basis of a fair comparison between the two kinds of belt working on similar ores. The conditions under which the work was done were the following :

Jan 1, 1893

By L. A. Jr. Norman

ANOTHER chapter in the history of Mother Lode mining is being written by operations in the Old Eureka mine near Sutter Creek, Amador County, California. During a two-year period (1938-1939), 85,517 tons of ore averaging 0.62 oz. gold per ton were mined and milled, as compared to the production of approximately 210,000 tons of 0.315-oz. gold ore during the preceding seven years. This is a repetition of mining history in the Mother Lode, where a period of prosperity has followed a long period of lean production. The location of this new ore in the hitherto unproductive hanging-wall greenstones and its mining and geological developments are most interesting.

Jan 1, 1939

By Joseph G. Wargo

A meteoric rise in selling price has revived gold exploration activity throughout the world. In the United States the effort is, in large measure, channeled toward discovery of disseminated gold deposits such as the Carlin-type, i.e., with size and grade characteristics similar to Newmont's Carlin mine in Nevada. The subtle surface indications characteristic of Carlin-type gold mineralization have been examined by a number of geologists, and the more obvious prospects have been tested by surface sampling and drilling. It is likely that most of these readily recognizable deposits have already been found and, as a consequence, prospectors are now entering a new, second stage of exploration for Carlin-type and related disseminated gold deposits.

Jan 9, 1979

By Charles A. Ashburner

[The statistics contained in this paper were collected for the United States Geological Survey and communicated to the Institute, by permission, prior to their publication in the report on the Mineral Statistics of the United States for 1887.1 The total coal-production of Alabama in 1887 was about 1,950,000 short tons, the spot-value of which, at the mines, was $2,535,000. The coal-regions of the State lie in the extreme southern part of the Appalachian coal-field, the northern part of which lies along the western New York-Pennsylvania State line; between these limits, New York on the north and Alabama on the south, portions of the

Jan 1, 1889

By R. H. Raring, F. E. Martin

A high speed gas quenching dilatometer useful in studying phase transformations in low alloy steels is described. Changes in specimen length are measured by means of an electrical micrometer tube. The maximum instantaneous cooling rate is approximately 5000°F per sec; the maximum average cooling rate from 1650' to 950°F is approximately 2900°F per sec. Data for steels of 0.11 pct and 0.67 pct C content are included. KNOWLEDGE of phase transformations as they occur in an alloy under conditions of continuous cooling affords valuable insight into its properties. The transformation characteristics during continuous cooling of steels of high hardenability, which decompose entirely to martensite at fairly slow cool-

Jan 1, 1957

By Carl Swartz

IN the course of a recent investigation1 to develop a more satisfactory white-metal. bearing alloy, a number of alloy systems were studied. The cadmium-nickel system showed characteristics desirable in a bearing alloy, and the system was therefore studied in some detail. EXPERIMENTAL METHOD Alloying cadmium with nickel offered no serious difficulty. After melting the cadmium, clean sheet nickel was added while the temperature was maintained at 500° to 600° C: A few crystals of ammonium chloride2 served to clean the nickel when the latter did not "wet" readily. In preparing the individual alloys for thermal and microscopic investigation, a "hardener" containing about 10 per cent nickel was used.

Jan 1, 1933

By J. H. Fletcher

AIR has been cooled, heated, washed; humidified and dehumidified for many purposes and in many industries. At a number of metal mines air is conditioned to reduce the high humidity and unbearable heat found in deep workings, and at some mines air is washed to allay siliceous dust. Steam is introduced into the intake air at many coal mines, particularly in winter, for the purpose of keeping loose coal dust so moistened that the hazard of an explosion is lessened. This paper will describe a further successful application of air conditioning in a coal mine, where, for over three years, all intake air has been cooled to a constant temperature for the sole purpose of preventing roof falls.

Jan 1, 1931

By James E. Little

Of the several extensive deposits of brown iron-ore in Cuba, including those of Mayari and Moa, that of Mayari was the first to be systematically explored, and was selected as the scene of the first operations in the development of this class of ore. Construction-work, begun in the spring of 1907, involved the building of 16 miles of stantlard-gauge railroad and two large double-track inelines, the installation of milling-machinery, a nodulizing-plant, power-plant, shops and shipping-facilities, and the dredging of an extensive basin for deep-draught vessels. Unusual weather-conditions delayed the completion of portions of this work so that the entire plant was not in operation until December, 1900.

Jan 1, 1912

By L. O. Millard

Stockpiles in the minerals industries serve a wide variety of purposes. Usually they are for surge between stages of processing, for a dependable plant feed in anticipation of delays, or to provide for single or double shift mining in conjunction with round-the-clock milling. Often surge piles are necessary to insure a uniform feed to continuous process equipment where the material is received as an intermittent or variable flow. Extensive use is made of stockpiling for the primary purpose of blending. The significant fact about all stockpiling of bulk materials is that storing and reclaiming are two separate and distinct operations and they may present widely different problems in the selection of methods and tools.

Jan 10, 1959

By Stephen Krickovic

THERE is today no proven continuous mining machine that can be used under all the varying conditions found in most bituminous coal mines. During the last five years, however, both the machines and methods of using them have been improved. Coal operators can now exercise a fair degree of selectivity, except those who must struggle with thick and hard partings and operate in seams less than 40 in. thick. It must be realized, then, that more than one type of continuous miner may be used advantageously in the same coal mine. Although this appears to violate the standardization generally sought after, the gain can more than offset added maintenance and, to a lesser degree, operating problems.

Jan 12, 1957

By Henry Tobelmann

THE location, mode of occurrence of ore, and preliminary tests leading to the development of the present leaching process and the building of the present plant on the property of the New Cornelia Copper Co. at Ajo, have been described in previous papers presented to the Institute and in the, discussions thereof.1 It is sufficient to say that these tests began early in July, 1912, and were continued to the close of January, 1916; that small tests at Douglas were followed by the construction of a 1-ton plant at the mine; and this was followed by the operation of a 40-ton plant for 14 mo. In all about 15,000 T. of ore were treated experiment-.

Jan 2, 1919

The Climax design is for the human being and his needs. Climax President Arthur Bunker has likened the high mountain operation to a giant, 250 million tons in weight, and 12 thousand feet high. No matter how huge or complicated the plant, the design must assure efficient operation by its human operators. By the same token, living and playing facilities must be designed for fullest satisfaction in use-else the capital investment is not justified. Even the product, molybdenum, finds its application through the ever growing demands of a highly industrialized society of humans. Research in Climax Laboratories, in tune with our technical age, helps guide molybdenum to its maximum use for society.

Aug 1, 1955

By R. J. Wasilewski

Elastic constants have been determined on single crystals of maximum-melting-temperature NiAl compound (50.6 at. pct Al) at 25°C. Temperature variations of Young&apos;s modulus in the three principal crystal directions between -150°C and +800°C exhibit no anomalies similar to those repovted for the isomor-phous compounds brass and AuCd. It is concluded that the ordered CsCl structure is stable throughout the temperuture range investigated NICKEL aluminide is a congruently melting inter-metallic compound of CsCl (B2) structure, stable over a rather wide composition range (40 to 54 pct Al). It exhibits a lattice-parameter maximum of a. = 2.883A at 50.6 pct 1,&apos; at which composition the excess aluminum atoms are randomly distributed on the vacant nickel sites;&apos; at higher nickel compositions the excess nickel atoms replace substitutionally in aluminum sites, while at higher aluminum compositions vacancies are present in the nickel sublattice.&apos; For compositions close to NiAl no significant variation in order has been observed at temperatures up to 900°C.3 At high nickel (65 pct) compositions the existence of a martensitic structural transformation has been reported.4 NiAl is isomorphous with the ordered B-brass structure and with the high-temperature structures of AuCd and TiNi alloys close to equiatomic composition. All of these exhibit anomalous elastic behavior as the temperature of their diffusionless transformation to lower-symmetry structures is approached.&apos;-&apos; This behavior has been explained as indicative of low stability of the CsCl structure in these compounds.8 The present paper reports the experimental determination of the elastic compliances of single-crystal NiA1. EXPERIMENTAL METHOD 1) Specimens. Polycrystalline NiAl was prepared by induction melting of carbonyl nickel and high-purity aluminum and casting into solid copper molds in gettered helium atmosphere. The castings thus produced were canned in mild steel and impact-extruded at 1100 to 1200°C to 38-in.diam rod. After the steel sheath was pickled off, the rods were converted to single crystals by repeated high-frequency satisfactorily produced the desired orientations in the form of crystals 38 in. diam by 8-12 in. long. These were subsequently center less-ground to 7 to 8 mm diam by 12 cm long, electropolished (in 80 pct methanol, 20 pct HzSO, at 25°C and 15 v), and their axial orientation determined to 1 deg by the Laue back-reflection technique. The rod dimensions were determined to 0.01 mm and the densities determined from geometrical dimensions and the weight of every specimen. The average density was 5.905 0.005 g per cu cm. 2) Elastic Data Measurements. Room-temperature elastic compliances Sii were obtained by determining to 0.1 cps the fundameGtal resonance frequencies in the longitudinal and torsional vibration modes. At these frequencies the following relations hold: E =p(2lfif =pvl= Sn- 2r[Sll- S12- -£„«] g -P(2iftf = pvf = (s<« - fr(sii - sw - ±s»y where vl and vt are the velocities, and f andft the resonance frequencies of the longitudinal and torsional waves, respectively; 1 is the length of the specimen, and r is the direction cosine factor—{cos2 a • cos2 0 + cos2 a . cos2 y + cos2 0 ¦ cos2 Y}. Given three crystals of orientations (loo), (110), and (111)) i.e., F = 0, 14, and 13, we can obtain six equations for the three unknown compliances, thus providing adequate internal check. Mode mixing can readily occur in the relatively long wavelength resonance utilized here. This could cause a significant error in the torsion wave velocities calculated from the apparent resonance frequenies. Therefore, throughout the present work, a method, described previosl,&apos; was used to ensure that no significant mode mixing took place at resonance. The apparatus used was originally designed for the Elastomat, Magnaflux Corp.. Chicago, 111. determination of flexural vibration resonance frequencies. At room temperature torsional vibration mode could be established by suitable positioning of the thin wires from the input and pick-up transducers, and longitudinal mode by cementing thin magnetic foils at the ends of the specimen, and inducing the vibration by means of electromagnetic transducers. Only flex-ural resonance frequencies could, however, be obtained reproducibly over the temperature range of -150 to 800°C. These data are considerably less accurate, the error in the modulus being estimated at -0.6 pct from the specimen dimensions and the room-temperature Poisson&apos;s ratio. The reproducibility of the resonance frequencies in repeat runs was, however, to better than l in 15,000, hence the relative elastic modulus error less than 0.02 pct. Therefore, the temperature variation of the principal Young&apos;s moduli obtained by flexural resonance, relative to room-temperature values, is believed to be satisfactorily accurate.

Jan 1, 1967

By R. A. Davidson, L. Silverman

RESIDENTS of many urban centers are becoming increasingly aware of the obscuring effect of fume and smoke discharge from power, metallurgical, chemical, and other industries; and they, as well as the legislatures of these affected cities, are agitating for cleaner air. Management&apos;s most pressing problem is to find an economical way to reduce process effluents in response to the growing pressure from population and legislative demands. The removal must be done, if possible, without handicap to the current operation, since the costs of relocating are often excessive or prohibitive. In fume recovery or disposal, an important item to consider is whether or not the material being discharged has any value. If it has commercial value, the cost of its recovery may offset or aid amortization. For this reason, in making a study of the specific problem in hand, a major factor was the nature of the material emanating from the stack: in particular, its particle size, size range, and its chemical and physical composition, as well as its potential value and utility when recovered (in either a wet or dry state). Should the product have no commercial value, it must be disposed of at minimum cost in a way to prevent recontamination. Initial studies were therefore made to determine stack concentrations and volumes of material evolved from the operations. The next phase of the study concerned the physical and chemical nature of the collected fume. The third portion of this paper describes the wet and dry collector studies undertaken to recover the fume. Cleaning Requirements for Ferroalloy Furnace Operation The basic need for any effluent collection equipment is the highest possible efficiency and the lowest tolerable resistance when the power consumption involved is considered. Since the electric furnace effluent is largely composed of fume of small size (less than 0.5u), it has high light obscuring properties, and even low concentrations will cause some loss of visibility and be evident to nearby residents. The permissible limit for fly ash emission in many cities is based on a weight value (viz, approximately 0.4 grains per cu ft), but the smoke density values are dependent upon a shade of color. In the case of the Los Angeles County code, emission is restricted to pounds per pound of material processed per hour basis (but not exceeding 40 lb per hr for any one given plant operation). If an average particle size of the fume from ferro-silicon alloy electric furnaces is assumed to be 0.4u (as shown later, this is the approximate mean size) and an average loading of 1 grain per cu ft (stp), each cubic foot of stack gas will contain approximately 75x10 10 particles (based on assumed, and confirmed, spherical shape and a standard deviation of unity). When it is realized that the air in metropolitan areas, which are also general industrial areas, contains approximately 5x108 particles, the tremendous light scattering effect of this concentration becomes apparent. Consequently, nearly 100 pct collection would be necessary to equal the average concentration. Fortunately, however, discharge from a high point above ground (50 to 100 ft) will result in at least a thousandfold dilution, or the stack concentration reaching the ground in the foregoing case might result in a ground concentration of &apos; particles. If the concentration at the source could be reduced by a factor of 100 (99 pct efficiency of collection), then a concentration of 75x10" particles would be diluted to 7.5x10&apos; which would be very satisfactory. An efficiency of 90 pct (factor of 10 decontamination) at the source would result in a discharge of 75x109 articles which upon dilution yields 75x10 which is still 15 times the general air value. Another approach to this consideration is to use the value of concentration of 0.005 grains per cu ft for the value of a visible effluent as cited by Kayse.1 To attain this value with an average loading of 1 grain per cu ft would require an efficiency of 99.5 pct. Since the foregoing value is not based on any reported size of fume particles, it is felt that the numbers&apos; approach given previously is more reliable. These calculations serve to indicate the desirability of thorough cleaning, preferably at the source, and with efficiencies well above 90 pct, preferably above 95 pct (dilution 1:20). One of the most important items in any control program is to reduce the concentrations as close to their sources as possible. The use of better furnace design, deeper coverage over the electrodes, and the prevention of blows or breaks in the surface all help to reduce dissemination; consequently, all of these improvements should be made, if possible, to cut down the effluent load. In addition, in order to minimize the volume of contaminated air that has to be cleaned, the furnace should be enclosed as much as possible. Test Arrangements Before fundamental studies with collectors were made, a furnace stack selected for the test program was sampled to determine the gas temperatures and

Jan 1, 1956

By S. R. Bardsley, S. T. Algermissen

Induction, nuclear and sonic well-logging methods were employed in a Green River formation oil-shale analysis and evaluation study conducted in northeastern Uintah County, Utah. The physical and chemical properties of an oil-shale section, previously cored and assayed by conventional methods, were used to evaluate the response of the various logs. The logging program was designed to measure variable properties of oil shale which relate to oil-yield potential in order that a relationship between assay-oil yield and log-determined properties could be identified, thereby permitting a direct determination of yield potential from logs alone. All of the major oil-shale zones and section ttlarkers are recognizable on the logs used in the study. The relationship between the response of the Density and Sonic logs and the assay-oil yield in gallons per ton was suficient to perinit the derivation of equations expressing the relationships. These equations can be used to determine the potential oil yield in gallons per ton of an oil-shale zone or section. The Neutron log response distinguishes the rich oil-shale intervals from the lean intervals, but does not appear to permit establishment of a quantitative relationship. The Garnma-Ray and Induction logs indicate only a qualitative relationship to oil-shale yields. Logging oil shale by Gamma-Gamrna Density and/ or Sonic logging methods will permit a fast, economical and accurate means of evaluating the potential yield of oil-shale deposits. Considerable sums of money have been allocated to Green River formation oil-shale evaluation during the past years by both private enterprise and Federal and state governments. The result of the work accomplished to date is commendable, but the task of fully exploring and evaluating one of the world&apos;s greatest reserves of potential energy for economical exploitation is enormous and much information is still needed. Present methods of evaluation consist primarily of sampling and assaying the oil shale for potential yield. The data received are excellent, but are both costly (inasmuch as it requires funds specifically allocated for the evaluation purpose) and time-consuming (as each representative sample must be assayed in the laboratory by specially trained personnel). At the present time, the Green River formation oil-shale province is one of the most active areas in the Rocky Mountain region for exploratory oil and gas drilling. This activity could play a twofold role and serve the function of spear-heading many oil-shale evaluation programs, as it could provide both cutting samples for assaying, geophysical data and modern well logs. This paper deals with a recent study conducted on Green River formation oil shale in which the application of induction, sonic and nuclear well logs to oil-shale evaluation was tested and proved. THEORY AND DEFINITIONS Oil shale may be described as siliceous marlstone, rich in solid organic matter called "kerogen". Kerogen is only slightly soluble in organic solvents, but it will decompose and yield oil vapors and gas when heated to destructive distillation temperatures at about 800 F. The mineral constituents of Green River formation oil shale are found in essentially uniform proportions with one another. The dominant types are, in the general order of abundance, dolomite, calcite, feldspars and quartz. Kerogen is also essentially uniform in its composition, and is about 80 per cent carbon and 10 per cent hydrogen by weight. The ratio of kerogen to the mineral constituents determines the richness or potential yield of the oil shale. This ratio also determines the total physical and chemical properties of the rock and provides a basis by which oil-shale richness may be determined from well logs. Because Green River formation oil shale was deposited in a lacustrine environment, the lithology is laterally consistent over wide areas. The vertical section consists predominantly of thin bands of alternating rich and lean oil shale which have been described by Bradley&apos; as varves. The varves are occasionally broken by thin bands of volcanic ash and tuff and by zones of lean vugular oil shale. The effect that the thin non-oil shale beds and vugular zones would have on the well log analysis was a prime concern in the study. To cope with this possible problem, the logs used in the study were of two types: (1) logs believed to respond favorably to those properties of oil shale which are dependent upon the kero-gen-to-mineral ratio, these logs being the Gamma-Gamma Density log, the Sonic log and the Neutron log; and (2) logs that would respond to litho-logies and properties within the oil-shale section not associated with yield that might result in anomalous responses by the yield-measuring logs. Logs of the second type were the Gamma-Kay log, the Induction log and the Caliper log. THE PRESENT STUDY The present logging study was con-

By H. E. Mauck

The many factors that control bumping must be carefully studied for each coal seam where bumps occur, and specifications known to exclude bumping should be incorporated in the mining plans. This calls for complete knowledge of the seam&apos;s characteristics and its adjacent strata, and in many instances these characteristics are not revealed until the seam is actually mined. Pressure and shock bumps, the two general types, occur jointly and separately. In this discussion no differentiation will be made. Whether pressure or shock, they are treated as bumps, and both must be eliminated. Bumps in mines have occurred in several places throughout the coal fields of the world. A study of many of these occurrences indicates that geologic characteristics, development planning, and mining procedure have contributed. But more specifically, there are conditions usually associated with bumps: thickness of cover, strong strata directly on or above the seam, a tough floor or bottom not subject to heaving, mountainous terrain, stressed and steeply pitching beds, and the proximity of faults and other geologic structures. Mine planning should incorporate these known factors (not necessarily in order of importance): 1) Main panel entries should be limited to those absolutely necessary to ventilate and serve the mine. This reduces the span over which stresses may be set up that will later throw excessive pressures on barrier and chain pillars when they are being removed. 2) Barrier pillars should be as wide as practicable so that they will be strong enough to carry the loads thrown on them when final mining is being carried out. 3) Pillars should never be fully recovered on both sides of a main entry development if the barrier and chain pillars are to be removed later. The excessive pressures placed on the main chain and pillar barriers by arching of the gob areas can result in bumping when these barriers are being removed. 4) Full seam extraction is better accomplished by driving to the mine boundary and then retreat-drawing all pillars. If there are natural boundaries in the mine—such as faults, want areas, and valleys —retreat should be started there. 5) Pillars should be uniform in size and shape. The entire development of the mine should call for uniform blocks with entries driven parallel and perpendicular. Only angle break-throughs should be driven when necessary for haulage, etc. 6) For better distribution of rock stresses and reduction of carrying loads per unit area, both chain and barrier pillars should be developed with the maximum dimensions. 7) Pillars should be open-ended when recovered. If they are oblong, the short side should be mined first. Both sides of a block should not be mined simultaneously, but under no circumstance should the lifts be cut together. 8) Pillar sprags should not be left in mining. If they are not recoverable, they should be rendered incapable of carrying loads. 9) Pillar lines should be as short as practicable. (Three or four blocks are adequate). Experience has shown that rooms should be driven up and retreated immediately. The longer a room stands, the more unfavorable the mining conditions. This contributes to bumping. 10) Pillars should not be split in abutment zones (high stress areas lying close to mined out areas) and if slabbing is necessary, it should be open-ended. 11) Pillars should be recovered in a straight line. Irregular pillar lines will allow excessive pressures thrown on the jutting points. Experience has shown that the lead end of the pillar line can be slightly in advance. 12) Pillar lines should be extracted as rapidly as possible. This appears to lessen pressures on the line and render abutment zones less hazardous. 13) Extraction planning should call for large, continuous robbed out areas. Robbing out an area too narrow to get a major fall of the strata above the seam tends to throw excessive pressures on a pillar line. 14) Timbering in pillar areas should be adequate but not excessive. Too heavy timbering or cribbing is likely to retard roof falls and throw excessive weight on the pillar line. 15) Experience has shown that when pillar lines have retreated 800 to 1000 ft from the solid, bumps can occur. Because this distance may vary in different seams, impact stresses should be studied for each individual condition. In any event, extra precautions should be taken against bumps in this area. This list of controlling factors may or may not be complete. It probably is not, but it covers most of the problem&apos;s significant aspects. The question is whether or not bumping can be eliminated. The answer is that bumping can be minimized and possibly eliminated if these and other established factors are thoughtfully considered and incorporated in the mining and extraction plans. If a mine has already been developed or the pattern set so that little change can be made, then it will be necessary to adjust to the most nearly practicable system that can incorporate the known factors.

Jan 1, 1959

By A. Lubinski, W. D. Greenfield

Bumper subs are currently used in offshore operations to permit a constant weight to be carried on the bit while drilling, regardless of the vertical motion imparted to the drill pipe by drilling vessel heave. As shown in this paper. the vertical motion of the lower end of the drill pipe (the bumper sub end) may be appreciably greater than the vessel heave. Therefore, the necessary stroke of bumper .rubs for successful operation is greater than thought in fie past. Also, there is an appreciable tendency of the drill pipe to buckle above the unbalanced type of bumper sub. Thus, more drill collars than previously used should be carried above unbalanced bumper subs to keep drill pipe straight. INTRODUCTION Drilling bumper subs are placed in the drilling string for various reasons. This paper is concerned with their use only as an expansion and contraction joint while drilling from a floating rig. In this application the bumper subs are normally located just above the drill collars and their function is to allow the driller to maintain accurate weight control on the bit regardless of up-and-down movement of the drilling vessel. This paper analyzes the effects of bumper subs on the drilling string and presents recommendations for their future use. When subjected to vertical oscillations, the drilling string behaves like a long, distributed system of mass and spring. The magnitude of vertical motion at the bumper sub is always greater than the heave of the drilling vessel due to the dynamic reponse of the drilling string. The ratio of these motions increases with the length of the drilling string, and may reach values of 1.5 or even 2 with strings 16,000 ft long. Thus, the total travel required in bumper subs can be considerably more than the motion of the drilling vessel. Lack of knowledge of this fact could have contributed to problems previously experienced with bumper subs. This fact can also lead to fatigue problems in the drilling string for very deep wells. Satisfactory operation should be obtainable whether hy-draulically balanced or unbalanced bumper subs are used in the drilling string. Theoretically, the balanced sub is preferable since its use does not require placing drill collars above the bumper sub to prevent drill-pipe buckling, an inherent characteristic of the unbalanced bumper sub. The current method of calculating weight of drill collars required to prevent helical buckling of drill pipe above unbalanced bumper subs is erroneous. Placing drill collars above the sub to prevent drill-pipe buckling has the same effect on dynamic response as increasing the length of the drilling string by an equal weight of drill pipe. Thus, total travel required in the subs is increased. Means for calculating the correct weight, which is much greater than previously thought, are given in this paper. BALANCED VS UNBALANCED BUMPER SUBS A drilling bumper sub is essentially a telescopic joint capable of transmitting torque at every position of its stroke. Thus, it allows the operator to isolate the weight of the drilling string from the weight of the drill collars above the bit. This permits the driller on a floating rig to maintain accurate control over the weight on bit — a control that is unaffected by vertical motion, due to wave and tide action of the drilling vessel. UNBALANCED BUMPER SUBS The unbalanced bumper sub is simply a splined tele~copic joint (Fig. I). Ordinarily, this arrangement will operate satisfactorily, but the presence of drilling fluid under pressure results in a pressure force that acts downward on the drill collars and bit, tending to open or extend the bumper sub. This downward force is equal to the pressure drop across the bit times the area indicated by diameter d2 in Fig. 1. Denoting this force by Fd, and the pressure drop across the bit by ?p yields Fb = (p/4)d22(?P) .........(1) There is also an upward-directed force given by Fu = (p/4) d22-d21)(?p) .......(2) which puts the drill pipe immediately above the bumper sub in compression, resulting in helical buckling. However, buckling is actually more severe than expected in that buckling occurs as if the compression were equal to Fd, rather than to Fu. This surprising phenomenon is well known as far as tubing is concerned;1-3 but, in contrast with the case of tubing, this force may shorten drill pipe only a few inches. Thus, this cannot explain the operating difficulties that sometimes have been encountered. However, having the drill pipe in compression and helically buckled is contrary to current practice; therefore, drill collars whose weight in mud is equal to the force Fd should be added above the bumper sub. Since the value of Fd depends on the pressure drop across the bit, the

By H. Conrad, V. Damiano, J. Hanafee, N. Inoue

The effects of hydrostatic pressure up to 400 ksi at 25" to 300°C on the mechanical properties of three forms of commercial beryllium (hot-pressed block, extruded rod and cross-rolled sheet) were investigated. Three effects of pressure were studied: mechanical beharior under pressure, the effect of pressure-cycling, and the effect of tensile prestraining under hydrostatic pressure on the subsequent tensile properties at atmospheric pressure. For all three materials the ductility increased with pressure whereas the flow stress did not appear to be significantly influenced by pressure. An increase in the subsequent atmospheric pressure yield strength generally occurred as a result of pressure-cycling or prestraining under pressure, whereas either no change or a decrease in ductility occurred. The only exception to this was sheet material, which exhibited some improvement in ductility following a pressure-cycle treatment of 304 ksi pressure. The effects of pressure-cycling and prestraining were relatively independent of the temperature at which they were conducted. Stabilized cracks of the (0001) type were found in hot-pressed specimens and {1120) type in extruded and sheet specimens following straining under pressure. Also, pyramidal slip with a vector out of the basal plane, presumably c + a, was identified by electron transmission microscopy for extruded rod and for sheet strained under pressure. Small loops similar to those previously reported were found after straining at pressures of the order of 300 ksi. THE use of beryllium in structures is limited because of its poor ductility under certain conditions. Therefore, one objective of the present research was to determine if the ductility of beryllium at atmospheric pressure could be improved by prior pressure-cycling or prestraining under hydrostatic pressure. Another objective was to study the mechanisms associated with the plastic flow and fracture of the polycrystalline form of this metal with pressure as an additional variable. Since the early work of Bridgman,1 it has been recognized that many materials which are brittle at atmospheric pressure exhibit appreciable ductility when strained under high hydrostatic pressure. This effect has been reported for beryllium by Stack and Bob-rowsky2 and by Carpentier et al.3 and has been attributed to the operation of pyramidal slip systems with slip vectors inclined to the basal plane while cleavage or fracture is suppressed.4 That such slip may occur simply by the application of pressure alone without external straining (pressure-cycling) is suggested by the results on polycrystalline zinc5 and polycrystalline beryllium,6 where nonbasal dislocations with a vector (1123) were reported. A significant improvement in the ductility of the bee metal chromium by pressure-cycling has been reported.7 On the other hand, limited studies on the pressure-cycling of the hcp metals zinc67819 and beryllium6 indicated no improvement in ductility; there only occurred an increase in the yield and ultimate strengths. The study on beryllium was limited to hot-pressed material. Consequently, additional studies on the effects of pressure-cycling on other forms of beryllium seemed desirable, especially since for chromium some authors10 have been unable to detect any improvement in ductility while others find a large improvement.7 That the ductility of polycrystalline beryllium at atmospheric pressure might be improved by prior straining under hydrostatic pressure was suggested by the known beneficial effects of cold work on the ductile-to-brittle transition temperature in the bee metals. It was reasoned that, by straining under hydrostatic pressure, fracture would be suppressed, and during the propagation of slip from one grain to its neighbor dislocations with a vector inclined to the basal plane"-&apos;4 would operate. Upon subsequent straining at atmospheric pressure, these dislocations with a nonbasal vector would continue to operate and thereby reduce the tendency for fracture to occur, by assisting in the propagation of slip across grain boundaries and by interacting with any cracks that may develop. It was recognized that maximum improvement in ductility would probably occur at some optimum amount of prestrain under hydrostatic pressure. If the pre-strain was too small, an insufficient number of dislocations with a nonbasal vector would be activated; if it was too large, internal stresses (work hardening) might increase the flow stress more than the fracture stress, or incipient cracks or other damage could develop. EXPERIMENTAL PROCEDURE 1) Materials and Specimen Preparation. The materials employed in this investigation consisted of hot-pressed block (General Astrometals, CR grade), extruded rod (General Astrometals, GB-2 grade with a reduction ratio of 8:1), and cross-rolled sheet (Brush S200, 0.065 in. thick). The analyses of these materials and mechanical properties at room temperature and atmospheric pressure are given in Table I. The grain size of the hot-pressed block was 15 to 16 µ, that of the extruded rod 10 to 11 µ, and that of the sheet 7 to 10 µ in the rolling plane and 5 to 6 µ in the thickness, all determined by the linear intercept method. Al-

Jan 1, 1969

By J. W. Snavely

WITH all the advantages of handling bulk materials by means of belt conveyor also go some problems, one of the most persistent being that of cleaning. When sticky materials are being carried; the build-up of material on the return idler rolls results in difficulty of belt training. Much attention has been given to the problem of cleaning conveyor belts, and a great variety of cleaning devices have been developed. Even the best involve troublesome maintenance, and none can completely remove the fine particles imbedded in the belt cover, which cause rapid wear of the return idler rolls, and at the same time, of the belt cover as well. One of the major rubber companies has been promoting a two-way belt system, in which the conveyor belt is given two successive 90" twists at each end to enable it to carry material in both directions simultaneously. For many years the flat belt transmission industry has installed quarter-turn and half-turn twists in countless numbers of instances. While quarter-turn and half-turn twists in transmission belts is a familiar application, the 180" twist apparently has never been previously attempted with a conveyor belt. About a year ago, two officials of the National Iron Co. of Duluth, Lester and Lewis Erickson, proposed twisting the return run of a conveyor belt on an installation that they were designing for one of the major iron ore producers. Since then the soundness of the idea has been demonstrated, both in theory and by practical test, with the result that the installation of two conveyor belts involving the twisting of the return run is now under way. These two installations are designed to have the return run of the conveyor belt twisted 180" as it leaves the snub pulley at the head drive. The clean underside of the belt is thus placed against the idlers on the return run as well as on the carrying run. Just before it enters the tail pulley, the belt will be twisted an additional 180°, restoring it to its normal position. Because this twisting of the return run of a conveyor belt is a radical departure from accepted practice, an elaborate and extensive test was conducted early in 1950 to demonstrate that this twisting of the return run could be done successfully, also to establish application data for accomplishing this twisting, and to determine if any special equipment would be required. In studying this concept of twisting the return run of a conveyor belt, a number of problems need to be solved, primarily the ones brought about by deliberately introducing an unequal distribution of stress across the conveyor belt and controlling that maldistribution of stress, while confining it to the return run portion. The tension conditions existing in the return run of a conveyor belt are clear to all designers. First, the return run carries the initial or slack side tension of the conveyor belt, the tension that must be supplied to the return run to provide proper frictional contact between the belt and the driving pulley so that the necessary power can be transmitted from the driving pulley to the belt without slippage. This slack side tension is supplied to the belt by means of takeups, either of the gravity type, which can be vertical or horizontal, or by means of the screw type. With inclined or declined belt conveyors the slope tension also must be considered, which is the tension imposed by the weight of the belt hanging from the top pulley. This slope tension frequently can furnish part or even all of the initial tension required. The maximum value of the slope tension will be at the top pulley, and it decreases in direct proportion to the length. In addition to the foregoing, it frequently is desirable to impose arbitrarily additional slack side tension to provide sufficient tension at the loading point at the tail, so that the belt will adequately support its load between the carrying idlers. Design Conditions for Twisting A number of design conditions exist, which must be satisfied successfully to accomplish the twisting of the return run without exceeding normal working limits in any portion of the conveyor belt. It is obvious that the belt edge, in its relation to the center of the belt, must stretch in making a twist, because as the twist is accomplished, the belt edge travels through a longer path than does the center of the belt. It is further obvious that if the edge of the belt is stretched, a redistribution of stress in the belt is required to allow this edge stretching. Moreover, this stress will be unequal across the width of the belt, having a maximum value at the edges, with a minimum value at the- center of the belt. With correct initial tension in the return run of a conveyor belt, the existing slack side tension will be unequally distributed when a twist is introduced. A condition then exists in which the edge stresses,

Jan 1, 1952

By H. A. Jr. Koch, C. A. Hutchinson

Miscible phase displacement of oil from reservoirs has been emphasized in the past few years. The reason for this emphasis lies in the high oil recovery attainable by this process. Removal of capillary effects in the reservoir leads to recoveries approaching 100 per cent in the area contacted by the miscible phase. The miscible slug process is one means of obtaining a miscible displacement. Here a band or slug of I,PG is injected into the reservoir prior to gas injection. The idea is to maintain the band of LPG "wedged" between the gas and oil phases and thus achieve a miscible phase displacement. A second method lor achieving miscibility is through the injection of a gas which is not miscible with the reservoir fluid but which develops a zone of miscibility in [he reservoir through mass trans-ier with the reservoir oil.&apos; This mass transfer results in either an enrichment of the lean injected gas by intermediates from the oil or an enrichment of the oil by intermediates from a rich injection gas or one that has been enriched on the surface by LPG addition. We are interested here in discussing the process in which miscibility is developed at the displacement front by the evaporation of interrnediatcs from the oil phase into the gas phase. This process "builds up" its own slug of miscible material at the displacement front and therefore does not require the injection of LPG to obtain miscibil-ily. Each process has its own area of applicability. Generally, the high pressure gas process is applicable only with reservoir fluids which con-!ain a high concentration of inter- mediates. If the high pressure gas process is technically feasible at pressures less than 4,500 psi, it is probably more desirable economically than the slug process. The slug process has broad applicability in the shallower reservoirs and with reservoir fluids which contain a relatively low concentration of LPG and natural gasoline constituents. This paper deals with some new concepts of the high pressure gas injection process where it is proposed that flue gas can be substituted for hydrocarbon gas without sacrificing our goal of miscibility. MECHANISM Introduction Considerable effort has been devoted to study of the mechanics ot the high pressure gas injection proc-one generalization result-ing from some of these studies was that the composition of the injected gas is relatively unimportant in establishing the miscibility pressure* for a given reservoir fluid. This generalization is correct for the composition range of gases typically encountered in the field. Two such gases are a gasoline plant tail gas containing 85 per cent methane and 15 per cent ethane, and a field separator gas containing 70 per cent methane and 30 per cent heavier components. The most important factor which sets the miscibility pressure in the operation is the reservoir fluid composition, particularly the concentration of LPG-natural gasoline constituents. The injected gas is the agent by which the LPG-natural gasoline constituents are concentrated at the displacing front to create a miscible displacement. Based on these results, it appeared feasible that some inexpensive gas, such as flue gas, might be substituted for hydrocarbon gas for use in the high pressure gas process. A re-examination of the phase relations of the high pressure gas injection process should clarify the principle behind using flue gas (essentially nitrogen) as an injection gas. Three Component Diagram The phase relations of the high pressure gas injection process have been illustrated by the use of the three component diagrams.&apos;," In Fig. 1 we have arbitrarily represented the multi-component reservoir system by three components; methane, ethane through hexane, and heptanes plus. The solid curve ABC is the phase boundary curve. It represents the locus of compositions which have fixed saturation pressure at a fixed temperature; the lower branch AB shows bubble point compositions, the upper branch BC, the dew point compositions. Point B is the coniposition of the critical mixture at this temperature and pressure. The dashed lines (tie lines) connect vapor and liquid compositions which are in equilibrium. Let us consider Reservoir Fluid D which we wish to displace in 21 miscible manner by gas injection. Let us further restrict the discussion to the case where miscibility between an injection gas and the reservoir fluid at the displacement front is developed by gas enrichment in the reservoir. For this case, any gas whose composition lies between Points C and E on the right side of the three component diagram can be used to give a miscible displacement of Reservoir Fluid D. This is true because the more mobile injected gas moves faster than the displaced oil and is in continuous contact with virgin oil at the displacement front. This leads to a continuing enrichment 01&apos; the gas at the displacement front by evaporation of the C, - C,