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By Ralph V. Higgins

This paper concerns the magnitude of the amount of supersaturation that occurs in an underground reservoir during the flow of oil and gas to wells and to the amount of undersaturation that occurs during repres-suring of an oil reservoir where some effective permeability to gas exists. The study is based on earlier laboratory findings of other investigators on the rate of diffusion of gas in oil as a function of the depth of oil. Utilizing these relationships and the principles of reservoir mechanics, a quantitative estimate of undersaturation and super-saturation was calculated. The results showed that the diffusion of the gas is rapid enough that for all practical purposes no supersaturation exists during the flow of oil to wells or undersaturation during repressuring in reservoir sands having some effective permeability to gas. The reason diffusion of the gas virtually keeps the oil saturated is the long time required in radial flow for oil to reach the well and the slow rate at which pressure in reservoirs is increased during repressuring. INTRODUCTION Knowledge of the phase relationships during flow of gas and oil in an underground reservoir is essential to operating the reservoir in the most efficient manner. In material-balance calculations and in fluid-flow studies, the oil is assumed to contain all the gas that it will dissolve at given temperature and pressure. Pressure-volume-temperature relationships are normally obtained in the laboratory using "bottom-hole" or combined samples of the reservoir fluids. In such laboratory determinations equilibrium is obtained between the oil and gas in the pressure cells by mechanical agitation. During the flow of oil and gas in reservoirs, however, no comparable agitation occurs to mix thoroughly these fluids to aid in effecting equilibrium between the two phases. During repressuring of a partly depleted underground reservoir, the gas is usually injected into the reservoir faster than the oil can absorb it; consequently, the oil is undersaturated. On the other hand, as the oil flows through the reservoir to the wells during producing operations the pressure decreases faster than the gas in solution can diffuse through the oil to the gas phase. The oil therefore is supersaturated with gas. Where the oil is undersaturated, gas diffuses away from the gas-oil interface, and where it is supersaturated the gas diffuses toward the interface. In either case the gas moves from a higher to a lower saturation. This report contains the results of a study of the factors influencing the degree of nonequilibrium of the phase relations of oil and gas in porous mediums during the flow of oil through reservoirs to wells and also during the injection of gas into partially depleted sands. Data from an underground reservoir are presented and the degree of supersaturation during the flow of the oil through the reservoir to the well is approximated. Also data from another reservoir are used and the degree of undersaturation during the repressuring operation is calculated. In addition, the flow rates of oil in laboratory experiments and in underground reservoirs are compared, as data from the laboratory are often used to interpret events in the reservoir, and the rates of flow influence appreciably the degree of nonequilibrium. Much of the contents of this report was prepared in 1943; but, because of other activities during and since the war, the manuscript was left untouched until 1952, when it was decided to include an estimate of the amount of undersaturation during repressuring as well as supersaturation during flow.

Jan 1, 1955

By AIME AIME

COMMITTEES. CANAL ZONE.-Col. George W. Goethals, U. S. A., Chairman; Lt.-Col. H. F. Hodges, U. S. A. ; Lt.: Col. D. D. Gaillard, U. S. A. ; Lt.-Col. William L. Sibert, IT. S. A. ; H. H. Rousseau, U. S. N.; Col. W. C. Gorgas, U. S. A.; Maurice H. Thatcher ; Joseph Bucklin Bishop ; Lt.-Col. Charles F. Mason, U. S. A.; S. B. Williamson ; Major Eugene T. Wilson, U. S. A. ; Edward Schildhauer ; Henry Goldmark ; Edward C. Sherman ; W. G. Comber ; W. B. Corse ; J. A. Walker; Joseph A. Le Prince; J. A. Smith ; Lt. Frederick Mears, U. S. A. HAVANA.-V. T. Polledo, Chairman; Diego Lombillo Clark, Jose Primelles, J. R. Villalon, Jose Artola, J. Ducassi, Luis Morales, Enrique Montonlieu. ENTERTAINMENT ON SHIPBOARD.-William L. Saunders, Chairman; Mr. and Mrs. S. D. Warriner, Mr. and Mrs. Thomas Robins, Mr. and Mrs. George.D. Barron, Mr. and Mrs. R. B. Watson, W. E. Greene. GENERAL MANAGEMENT. .Joseph Struthers, Chairman; Albert E. Vaughan. There were ten sessions of the Institute held for the presentation and discussion of, technical or professional papers. Eight of these sessions were held on the steamer while en route, and two in the ball-room of the Hotel Tivoli, at Ancon, C. Z. Mr. David W- Brunton, President of the Council, presided at all the sessions, except the sixth, at which Mr. Charles Kirchhoff, past President, occupied the chair. The following list includes the papers presented in oral abstract by the authors: First Session., October 24. The Summit Hill Mine-Fire, by W. A. Lathrop, Philadelphia, Pa. Mine-Fire at the Calumet and Hecla Mine, No. 8 Shaft., by S. D. Warriner, Wilkes-Barre, Pa. Fire in the Big Lick Stope, Lykens Valley and Williamstown Colliery, by R. V. Norris, Wilkes-Barre, Pa. Mine-Fire in the Hecksherville Valley, Schuylkill Field, Pa., by W. J. Richards, Pottsville, Pa.. Fire in the Monarch Mine, near Rock Springs, Wyo., by S. A. Taylor, Pittsburg, Pa.

Dec 1, 1910

By Frank G. Snyder

INTRODUCTION Numerous deposits of lead and zinc sulfides, often accompanied by barite and fluorite, occur in carbonate host rocks throughout central and eastern United States. So similar are the deposits in broad general characteristics that they long have been classified as Mississippi Valley type. They differ widely, however, in details such as metal ratios, age of host rock, type of ore-bearing structure, and probable time of mineralization. The theories developed to explain the source and transport of the metals are many and are known to all. The deposits have been termed telethermal on the basis of their presumably shallow occurrence and the attempt to relate the metals to the classic hydro- thermal sequence. 1t is now recognized that deposits of this type can occur at any depth; the only depth limitation is thickness of the sedimentary section. Ideas on the source of the metals also have changed, A rapidly growing body of evidence suggests that the metals were brought by concentrated brines from nearby sedimentary basins. The hypothesis preferred today by many geologists postulates that the metals were deposited during the course of normal sedimentation in depositional basins of miogeosynclinal or orthogeosynclinal type. At some time after deposition of the sediments, the metals were carried out of the basins by migrating brines; the brines moved laterally and upward into structurally high areas; they entered any reservoir-like structure, either primary or secondary in origin, that happened to be available; in this reservoir, possibly in a sulfur-rich environment, the metals were precipitated as ore minerals.

Jan 1, 1970

By C. W. Davis

THE name fuller's earth, which was derived from its early use in "fulling" or removing grease from woolen goods, is a term that is generally considered to designate mineral matter, containing hydrous aluminum silicates of the clay group, which has a high capacity for removing colors from oils, whether of animal, vegetable, or mineral origin. Fuller's earths are usually dried and may be "tempered" by heating or may be treated with water or reagents to improve their efficiency. For our purpose the term "acid-treated earths" will include those products from the partial decomposition of mineral water -by acid which are equal to or more efficient than an untreated fuller's earth from Quincy, Fla., when used in bleaching mineral oil by the "contact" process. In general, the contact process for treating oils consists of heating and agitating a mixture of oil and finely divided adsorbent, the latter being subsequently removed by filtration. The term "adsorbent" is used because, although there has been a great deal of controversy over the mechanism of removal of impurities from oils by mineral matter, there is no doubt that adsorption, which involves the surface of the solid, plays a major part.1 The properties that make fuller's earth useful in the treatment of petroleum products by "percolation" and in the purification of edible oils by the contact process have long been studied, but the comparatively recent adaptation of the contact process to the bleaching of petroleum products has made desirable the further investigation of fuller's earth and other, adsorbent earths.

Jan 1, 1929

By S. G. Lasky

EVENTS during and since the war indicate that the nations of the world are trying to initiate an era of international co-operation. Definitions and objectives include social, economic, and human considerations no less than political considerations. The mineral resources of the world and the absolute and relative position of each nation enter into this situation. The possible use of armed might, the application of sanctions, the international flow of commerce, the ways in which this flow may encourage or hamper international well-being, and the influence of international and domestic well-being upon one another are all matters that must take mineral resources into account. If the United States is to act wisely and forthrightly in such matters we must be thoroughly informed as to our position with respect to mineral resources. What is the mineral position of the United States? A variety of widely conflicting opinions are held in authoritative and intelligent quarters: (1) For practical purposes our mineral resources are already exhausted.

Jan 1, 1946

By AIME AIME

I am happy to welcome you to the twenty-third conference of the National Open-Hearth Committee, and our joint conference with the Blast Furnace Committee, of the American Institute of Mining and Metallurgical Engineers. It is appropriate that, for our fifteenth year anniversary, we should meet in the hotel and the city where this Open-Hearth Committee was inaugurated in 1925. At that first meeting, only a handful of men from a number of steel companies met to discuss ways and means to start a movement to improve the practical and metallurgical technique of open-hearth operations among independent manufacturers, as the United States Steel Corporation had carried on for many years.

Jan 1, 1940

By J. S. UNGER

A LARGE proportion of the coke used is made in the by-product oven from the high-volatile coals mined in the adjacent district. At the beginning it was feared good by-product blast-furnace coke could not be made with our coals. By experimenting with various mixtures of coals, coking time, oven design, and coking temperatures, much has already been accomplished. The results show that a hard, dense coke, not easily broken by handling, can be produced. In its present state it is not all that could be desired, but it is being constantly improved. Such coke has been used alone as the fuel on several of the blast furnaces producing the highest daily production in the Pittsburgh district. Many of the coals in the Pittsburgh district when coked in the by-product oven yield a gas which contains a high percentage of sulfur, which is objection- able for many metallurgical operations. As this fuel is gradually replacing the ideal fuel, natural gas, which is becoming less plentiful, studies are being made of the best methods for purification. Some metallurgists believe sulfur to be a very injurious element in steel. Recent investigations by Government bureaus, scientific bodies and private firms, seem to indicate that a reasonable amount of sulfur may exist in steel without detriment. Without wishing to provoke any metallurgical controversy on the subject of sulfur, the fact remains that the daily purification

Jan 1, 1926

By W. C. Spence, Burt C. Mariacher

Methods employed to beneficiate ores utilize relatively few fundamental principles to effect size reduction and concentration. In crushing and grinding only impact and compressive forces with a minor amount of shear are employed. In concentration, gravity, magnetic, electrostatic and flotation constitute the major methods of concentration with minor use of sizing, hand picking and adhesion. This industry, as all others, can expect in the near future to see the development of new techniques for improved efficiency, cost reduction, and exploitation of raw materials hitherto considered unmanageable. NATURAL AND INDUCED RADIOACTIVITY At the Canadian Department of Mines in Ottawa in 1946, C. M. Lapointe developed a picker belt system whereby radioactive ores could be concentrated by electromechanical means. This invention ultimately led to development of what is now refer- red to as the Lapointe Picker and which has been used commercially at Port Radium and Port Hope for the upgrading of jig concentrates. Basically, the system consisted of conveying sized uranium ore on a belt under a radioactivity detection device which in turn electronically operated a kicker or plunger that separated the ore from the gangue constituents. Thus, a new principle for mineral concentration, radioactivity, was introduced commercially.

Jan 7, 1962

By Oliver Bowles

EACH year the broad diversified field of industrial minerals offers a panorama of new and interesting developments that not only concern the welfare of the industries themselves but have a more or less direct influence on the lives of citizens at large. Thus, the home life of multirudes may be affected by new building units that transmit light through walls instead of windows, by illuminated processed marble lighting fixtures and decorations, by the vast impetus given to thermal insulation Ly .mineral wool, expanded vermiculite, and related products, and, more remotely, by fireproof rugs and drap-

Jan 1, 1937

By Robert M. Funk, James E. Lawver

The development of a laboratory and pilot-scale high-tension electrostatic flowsheet for the production of iron-ore super concentrates having silica contents in the range of 0.1% is presented, A variety of hematite and magnetite ores were tested with this flowsheet, and the pertinent metallurgical data are given. The applications and limitations of this process are brought out in terms of both practical and theoretical considerations. There have been many new developments in the past few years that have required mineral beneficiation engineers to consider new techniques for iron-ore concentration. Developments in iron powder metallurgy, and particularly the making of sheet metal directly from high-purity iron-ore concentrates, and the concept of using metallized pellets as a substitute for scrap in electric-furnace steelmaking have created demands for what is commonly referred to as iron-ore superconcen-trates. In most cases, specifications for superconcentrates are that they contain less than 0.1% total gangue, with some applications requiring less than 0.05% gangue. To produce these concentrates, new and modified processes are being developed, and the three methods receiving attention as the primary concentrating methods are: 1) Magnetic separation in which dry rotor-type equipment is used for magnetite and the high-intensity magnets are used for hematite. 2) Amine flotation. 3) "High-tension" electrostatic separation (or, elec-trodynamic concentration). This paper examines the high-tension electrostatic process in terms of its limitations and abilities for the production of iron-ore superconcentrates. A technically effective and simple flowsheet was developed through laboratory and 5 and 100-ton pilot-plant studies for the production of concentrates containing from 0.02 to 0.20% SiO, with iron recoveries between 85 and 90%. The process is also shown to be economically feasible. Laboratory Test Program Separation Characteristics: The suitability of the electrostatic high-tension method for iron-ore supercon-centration stems from the fundamental mechanism governing the process, i.e., particles are separated on the basis of differences in electrical conductivities. This conductivity is a characteristic property of minerals, and if the difference between the conductivities of two min- erals is great enough, then their separation can be performed by a high-tension machine. As shown in Figs. 1 and 2, the critical factor is the time necessary for the particle charge density, which is established by a corona discharge field, to decay to a level such that the centrifugal force acting on the particle exceeds its electrostatic, or image, force. At this point, the particle can leave the rotor at some trajectory and fall into an appropriate product receptacle. This decay time is directly proportional to electrical conductivity, and the process variables, such as feed rate, rotor speed, electrode configuration, and rotor composition, are selected to optimize the ability of the separator to resolve different conductivities. Table 1 lists the measured conductivities for some of the iron and gangue minerals used in developing the flowsheet. These results were obtained by using the conductivity cell described by Lawver and Wright.' The discharge curve of most minerals that lend themselves to super concentration by high-tension is so fast that the

Jan 1, 1971

By C. W. Davis, L. R. Messer

THE name fuller's earth, which was derived from its early use in "fulling" or removing grease from woolen goods, is a term that is generally considered to designate mineral matter, containing hydrous aluminum silicates of the clay group, which has a high capacity for removing colors from oils, whether of animal, vegetable, or mineral origin. Fuller's earths are usually dried and may be "tempered" by heating or may be treated with water or reagents to improve their efficiency. For our purpose the term "acid-treated earths" will include those products from the partial decomposition of mineral water by acid which are equal to or more efficient than an untreated fuller's earth from Quincy, Fla., when used in bleaching mineral oil by the "contact" process. In general, the contact process for treating oils consists of heating and agitating a mixture of oil and finely divided adsorbent, the latter being subsequently removed by filtration. The term "adsorbent" is used because, although there has been a great deal of controversy over the mechanism of removal of impurities from oils by mineral matter, there is no doubt that adsorption, which involves the surface of the solid, plays a major part.' The properties that make fuller's earth useful in the treatment of petroleum products by "percolation1' and in the purification of edible oils by the contact process have long been studied, but the comparatively recent adaptation of the contact process to the bleaching of petroleum products has made desirable the further investigation of fuller's earth and other adsorbent earths.

Jan 1, 1929

By Norman Yarborough

Much has been written about the energy fuels including their standing with respect to reserves, their delivered Btu costs, their potential in the electrical generating market and their capabilities to meet a burgeoning demand. Yet, when all factors are placed in their proper perspective, the spiraling electrical energy market alone should guarantee each fuel a better than average market for the foreseeable future. In fact, a study made by the U.S. Federal Power Commission on the spare capacity utilities have on hand indicated that 39 of the 181 major utility systems had less than 10% reserves on hand at the end of 1969. Fuel supplies are critically low in some areas, especially in the Southeast, South Central and Midwest areas of the U.S. In other systems equipment shortages resulting from faulty equipment or delays in getting new equipment deliveries causes power failures during peak loads. In addition, lack of labor curtails the erection of some new facilities and prevents many other facilities from operating at capacity.

Jan 1, 1970

By Rossiter W. Raymond

In the case of The Eureka Consolidated Mining Company v. The Richmond Mining Company of Nevada, recently tried at San Francisco, California, the real defendant was the Richmond Consolidated Mining Company, of London; but this being a foreign corporation, holds its mining property in Nevada through the Nevada corporation of similar name, in which the London Company owns all the stock, except the few shares necessary to " qualify" the American directors. The trial would naturally have taken place in the Circuit Court at Carson City, Nevada, and before a jury. But by stipulation of the parties, the case was tried in San Francisco, before Hon. Stephen J. Field, Justice of the Supreme Court of the United States, Hon. Lorenzo Sawyer, United States Circuit Judge of the Ninth Circuit, and Hon. E. W. Hillyer, United States District Judge, for the District of Nevada. The hearing began July 23d, 1877. The witnesses occupied two weeks, and the argument of counsel three days. Very eminent lawyers were engaged on both sides; for the plaintiff, Messrs. Solomon Heydenfeldt, R. S. Mesick, John Garber, and H. J. Thornton; for the defendant, Messrs. S. M. Wilson, Thomas Wren, and J. J. Williams. The court held the case under advisement until August 22d, when Mr. Justice Field delivered its unanimous opinion in favor of the plaintiff. The action was a complaint in ejectment, and an appeal was taken to the United States Supreme Court. The questions at issue between the Eureka and the Richmond Company in this suit, comprised several points in the construction of the mining law of the United States, and its relation to the customs and regulations of the mining districts, which possess an importance and an applicability far beyond the limits of the case in which they arose. It is my purpose to state these points, the arguments

Jan 1, 1879

By A. C. Fieldner

DURING 1939, 286 by-product coke ovens were completed and put into operation. These included 140 Witputte ovens for the Carnegie-Illinois Steel Corp., at Gary, Ind.; 61 Koppers-Becker ovens for the Ford Motor Co., at River Rouge, Mich.; 65 Semet-Sotvay ovens for the Great Lakes Steel Corp., Zug Island, River Rouge, Mich.; and 20 Curran-Knowtes ovens for the Midwest-Radiant Corp. plant at Mitlstadt, Ill. The Millstadt plant is unique in carbonizing a washed coat containing 3.50 per cent sulphur. The gas contains approximately 2500 grains sulphur per 100 cu. ft.; this is successfully removed with sodium carbonate solution by the Seaboard liquid purification process. The coke is intended primarily for use as a smokeless domestic fuel in the city of St. Louis.

Jan 1, 1941

Who's Who in Mineral Engineering - The 1978 Membership Directory of the Society of Mining Engineers of AIME

Jan 7, 1978

By U. K. Custred, E. W. Long, V. R. Degner

In 1973, the United States production of marketable phosphate rock set a record in excess of 42 million tons. This production rate is expected to continue to increase, due to the growing international requirement for fertilizer, at a rate exceeding 5% per year well into 1977. One approach towards increasing plant production capacity to meet the growing demand is through large-capacity flotation cells, provided they achieve metallurgical performance comparable to existing smaller cells. A 9-month evaluation test program recently completed at the Haynsworth mine at Bradley, Fla., demonstrated the feasibility of achieving economically acceptable concentrate grade and recovery levels using large, high-capacity flotation cells. The composition of the feed to the Haynsworth beneficiation plant is a typical Florida pebble phosphate matrix composed of phosphorite pebbles ranging in size from approximately 1-1/2 in. down to 150 mesh and intimately associated with a mixture of clay and sand (essentially silica). The feed contains approximately 22 to 28% phosphate reporting as tricalcium phosphate, Ca3 (PO,) 2, or "bone phosphate of lime" (BPL). The flotation section utilizes the double-float procedure typical of Florida plants. The phosphate is first floated away from the silica in the rougher circuit, using crude fatty acid, ammonia, and fuel oil or kerosene. Rougher conditioning is accomplished at 60 to 70% pulp solids with sufficient ammonia added to raise the pH to 9 to 9.5. Following coarse and fine rougher flotation, the concentrate (overflow) streams are joined and conditioned (sulfuric acid cleaned and washed) prior to entering the cleaner circuit where an amine float (cationic reagent and kerosene added in the feed box; pH 7.3 to 7.8) is employed to float the silica. The feed to the coarse rougher circuit averages 29% +35 mesh while the fine rougher feed averages 10%+35 mesh. Primary attention was directed toward the large rougher cell performance (recovery and grade) on coarse feed during the Haynsworth evaluation program. Flotation Cell Test Program A row of three No. 120 size (300 cu ft) WEMCO flotation cells was installed in parallel with an existing air-cell row. The total installed volume of the large cell circuit was 900 cu ft and required a floor space of 306 sq ft. This compared to the air-cell total volume of 200 cu ft and 152 sq ft floor space. (Both floor areas include feed and tails hoppers but exclude walkways.) Fig. 1 is a schematic cross section of the large flotation cell showing the relative location of key mechanism elements. In operation, the rotor generates a fluid vortex extending up along the walls of the standpipe and creating a sufficient vacuum within its core to ingest air into the standpipe/rotor cavity through the air inlet duct. The ingested air mixes with the pulp, which has been recirculated through the false bottom and draft tube, in the rotor. Further mixing occurs as the air and pulp move radially outward from the rotor, finally passing through the disperser into the flotation cell. Flotation is accomplished outside the disperser, where phosphorite laden air bubbles rise and the remaining pulp recirculates down along the cell wall to the false bottom and draft tube. Large-flotation-cell performance is influenced by the ability of the mechanism to (1) circulate, or suspend, the solids in the pulp; (2) ingest air into the rotor cavity; and (3) mix the air and pulp effectively. The proper balance between pulp circulation and air ingestion is a key consideration in achieving good recovery in a course feed application. Large-flotation-cell pulp circulation and air transfer characteristics are significantly influenced by rotor speed and rotor submergence; therefore, these two operational parameters can be used to "optimize" a particular mill application. Fig. 2 maps the hydraulic performance of the WEMCO No. 120 size flotation cell. This map can be used to relate the cell operational parameters which influence metallurgical performance. At a given rotor speed, power intensity (i.e., pulp circulation) is seen to increase, and airflow decrease, as rotor submergence is increased. The inverse relation between power and airflow is due to the two-phase air-liquid mixture density reduction accompanying the increased airflow rate. For any fixed rotor submergence, the power intensity (i.e., fluid circulation) and airflow both increase as rotor speed is increased. The selection of these two mutually related operating conditions (i.e., rotor speed and submergence) was a key consideration in the Haynsworth evaluation program.

Jan 1, 1976

By C. W. Davis

THE name fuller's earth, which was derived from its early use in "fulling" or removing grease from woolen goods, is a term that is generally considered to designate mineral matter, containing hydrous aluminum silicates of the clay group, which has a high capacity for removing colors from oils, whether of animal, vegetable, or mineral origin. Fuller's earths are usually dried and may be "tempered" by heating or may be treated with water or reagents to improve their efficiency. For our purpose the term "acid-treated earths" will include those products from the partial decomposition of mineral water by acid which are equal to or more efficient than an untreated fuller's earth from Quincy, Fla., when used in bleaching mineral oil by the "contact" process. In general, the contact process for treating oils consists of heating and agitating a mixture of oil and finely divided adsorbent, the latter being subsequently removed by filtration. The term "adsorbent" is used because, although there has been a great deal of controversy over the mechanism of removal of impurities from oils by mineral matter, there is no doubt that adsorption, which involves the surface of the solid, plays a major part.1 The properties that make fuller's earth useful in the treatment of petroleum products by "percolation" and in the purification of edible oils by the contact process have long been studied, but the comparatively recent adaptation of the contact process to the bleaching of petroleum products has made desirable the further investigation of fuller's earth and other adsorbent earths.

Jan 1, 1929

A price list of publications of the Geological Survey, complete to May, 1931, and with separate monthly notices of publications to (late, will be sent upon application to The Director, United States Geological Survey, Washington, D. C. A leaflet is issued each month listing new publications; it will be sent upon application to the Director, as well as Circulars containing information about topographic maps. Book publications of the Survey include (1) Annual Reports, (2) Monographs, (3) Professional Papers, (4) Bulletins, (5) Water Supply Papers, (6) chapters and volumes of Mineral Resources of the United States, (7) Folios of the Geologic Atlas of the United States and the World Atlas of Commercial Geology, (8) Topographic Folios and Topographic Maps that bear descriptive texts. Monographs, Folios of the Geologic Atlas of the United States and the World Atlas of Commercial Geology, and Topographic Folios and Topographic Maps, are not distributed free. A publication of one of the other classes can be distributed free only until the end of the fiscal year following that in which it was issued. No person can obtain more than one free copy of the same publication, and general requests for free publications, such as all of any series or all on any subject, can not be granted. In ordering publications one is requested to give both the series designation, as Bulletin 738 or Professional Paper 122, and the title. Give full address, plainly written, including county. Prepayment is required and may he made by postal, or express money order payable to the official charged with the sale of the publications. requested, as indicated in the discussion of each classification following; or it may be made in cash-exact amount -at sender's risk. Postage stamps are not accepted in payment for publications.

Jan 1, 1933

By Richard Kunter

INTRODUCTION Additional work has been done on the CIP circuit at Creede, and a brief description of this work is presented in this paper. DREDGE The original dredge for the Bulldog was built by Al Hack, Inc. of Denver. The dredge cutter head is mounted on a boom made of 6-inch diameter pipe which is raised and lowered by a cable-pulley system. Maximum cutting depth is 8 feet. Slurry from the dredge flows through a floating 6-inch diameter pipe supported on 55-gallon drums which runs from the dredge to the shore and then to a trash screen and pumping system. See Figures 1 and 2. The cutter head, suction pump, winches for dredge movement, and all other operations are controlled from a small operations house located toward the rear of the dredge. All of the basic dredge equipment is mounted on a chassis about 8 ft x 16 ft in size. Additional buoyancy was originally provided by sealed 55-gallon drums supported along the sides of the chassis by a small wooden framework. Additional framework and barrels on the front of the chassis on either side of the cutter boom provided additional stability, particularly when digging in hard material. The dredge was quite stable, but two problems were apparent. For one, it could have been sunk by someone from the shore firing a rifle into all of the barrels. In prime deer-hunting and sportsman country

Jan 1, 1983

By J. T. Norton, N. J. Grant, A. M. Gervais

An investigation of the creep deformation of coarse-grained high-purity aluminum at temperatures approaching the melting point permitted the formulation of a theory of subgrain formation. Subgrain boundaries were found to be formed by two different processes: kinking and polygonization. Polygonization is considered as the main factor in subgrain formation. SINCE "slipless flow" was first discussed in detail by Hanson and Wheeler,' many studies have been undertaken to determine how metals deform at high temperatures. Several types of observations have been reported. Jenkins and Mellor,² working on the creep of mild steels and various grades of commercial irons, found metallographic evidence of a kind of substructure within the grains after deformation at high temperatures. Homes" observed after creep deformation of steel at high temperatures that the original X-ray spots were sharply divided into several small ones. The same phenomenon was reported by Hirst4 from his studies on lead and later by Crussard5 from his work on aluminum. The works of these investigators demonstrated beyond any doubt that the splitting of the X-ray spots was due to the fact that the grains underwent a division into subgrains during deformation at high temperatures. Since then, numerous experiments have been undertaken on aluminum in order to determine the mechanism of formation of subgrains. Research workers can be divided, for the purpose of discussion, into two different groups as regards thinking on subgrain formation. On one hand, based on the work on polygonization by Cahn,6 Guinier and Lacombe,7 Greenough and Smith," Crussard,10,11 and Servi, Norton, and Grant," it was concluded that subgrain formation was a consequence of the simultaneous effects, first, of inhomogeneous deformation which produced bending of the lattice, and second, polygonization. On the other hand, Wood and coworkers13-16 based their work on the results of an earlier report" which dealt with crystallite size and a fragmentation theory. It is interesting to note that while Greenough and Smith8 and Wood et al. performed similar experiments, their conclusions were quite different. Wood et al. did not recognize polygonization as a fundamental mechanism and said that aluminum, at the beginning of the deformation, fragmented immedi- ately into subgrains in order to permit deformation of the metal, the number of these subgrains being a function of strain rate and temperature. They concluded that deformation of grains occurred by flow along the subgrain boundaries. In view of the contradictory conclusions, it would appear that the data were not explicit enough to provide an unambiguous conclusion. It appears that the techniques by which most of the results were obtained, namely, X-ray work, were not enough by themselves to solve the problem. Another approach was needed. In the present research, therefore, an extensive metallographic study was planned to supplement the X-ray work. The importance of revealing the subgrain boundaries metallographically was realized, and this will explain the extensive development and use of etching techniques. In order that subgrains would be considerably larger and therefore more readily visible under a microscope, the creep experiments were performed at very high temperatures approaching the melting point of aluminum. Development of Experimental Technique Creep tests were run at constant load on high purity (99.995 pct) aluminum specimens having a very coarse grain size. None of the specimens was run to fracture. The specimens were originally round (diameter, 0.187 in.; gage length, 1 in.) and had parallel flats milled in the gage section to permit

Jan 1, 1954