Search Documents

By J. B. Hess, R. L. Dietrich

In the mechanical twinning of magnesium on the {1012} planes the crystal-lographic deformation is such that, in the direction of the hexagonal axis [0001], twinning is possible only undef tension stress, while in the directions perpendicular to the hexagonal axis, twinning is possible only under applied compression. Thus in extruded magnesium and magnesium alloys where the extruded textures are best described as either [1010] or [1120] fibers,' the basal planes are all nearly parallel to the extrusion axis and such material is susceptible to ( 1or2 ) twinning by compression in the direction of the extrusion axis. In order to explain the results of cyclic stressing in alternate tension and compression upon the tangent elastic modulus in such material, Dorn and Thomsen2 have postulated that, following twinning under applied compression, a retwinning or un-twinning occurs as a result of residual microtensile stresses immediately upon removal of the applied compressive force. Recently, Carapella and Shaw4 have used this supposition of untwinning in magnesium in discussing their results on indentation hardness and on cold drawing of MI sheet. In trying to confirm this hypothesis by suitable direct experiments, the authors have been unsuccessful in detecting any evidence whatsoever that untwinning follows the release of applied compression and are forced to conclude that this hypothesis is improbable or, at least, that the quantity of material involved is small. For the experiments, small cylindrical specimens 0.040-in. diam. X 0.120- to 0.140-in. long were etched from 0.0625-in. extruded rod. The ends of the specimens were accurately faced off parallel in a jeweler's lathe. The compression jig was simply an ordinary set of micrometer calipers with an anvil interposed between the spindle and the specimen. The anvil was free to move axially but restrained from rotating so that the rotation of the spindle would not introduce a twisting stress on the specimen. With this arrangement the compressive strains could be estimated to 0.0001 in. and X ray pinhole photographs could be taken with or without load as required. Fig I is the pattern of an uncompressed specimen of AZ3I alloy, showing the approximate [1010] extrusion fiber. The X ray beam is normal to the extrusion axis; in this position it is particularly sensitive in detecting twinning if one directs his attention to the diffraction ring from the basal plane. Since twinning on (1072 planes produced an 86" reorientation of the crystal lattice, the original basal reflections occur at the 3 and 9 o'clock positions while the (0002) reflections from any twinned material will occur at the 6 and 12 o'clock positions. Fig 2 shows the same specimen compressed 3.0 pct, photographed while still under load. This strain has been just enough to produce a detectible amount of twinning and the sensitivity is roughly indicated by the fact that no alterations were produced in the intensities or maxima of the other diffraction rings. A strain of

Jan 1, 1949

By P. A. Beck

ACCORDING to the traditional definition,1 re-x crystallization is a process taking place upon annealing of cold worked metals, characterized by the appearance of new strain-free grains, growing at the expense of the cold worked grains until ultimately the new crystals completely replace the cold worked structure. In metals like brass this process was observed long ago to take place simultaneously with the return of the mechanical properties to those characteristic of well annealed material. The above definition implicitly assumes that the matrix in which the new grains are growing is essentially still in the cold worked condition at the time it is absorbed by the new grains, i.e., that the energy stored in the metal during cold working is not greatly decreased by recovery, prior to recrystallization. Accordingly, the bulk of this energy is assumed to serve as the driving force for the process of recrystallization. Recently, a great deal of evidence accumulated, indicating that the traditional concept may be considerably in error. Suzuki' found that by far the largest portion of the stored energy of cold work in compressed polycrystalline copper is released in the early stages of annealing, well in advance of recrystallization. Thus, the new recrystallized grains are undoubtedly growing in a matrix which is, at least energetically, no longer in the cold worked condition, but has nearly returned to the annealed state. It is true that in Suzuki's experiments the major hardness changes due to annealing were observed to take place concurrently with the formation and growth of the new grains, but this process apparently involved the release of only a minor residual fraction of the stored energy of cold work. Confirming in this respect the views of Wood," several recent investigations by various techniques lead to the conclusion that the grains of many, if not all, metals in the cold worked condition consist of small, slightly disoriented "crystallites" or "sub-grains".* (After appreciable deformation at room temperature, the subgrain size in copper appears to be about 7.104 cm and in high purity aluminum about 2.10-4 cm.) Recent investigations which demonstrated this phenomenon most convincingly are those of Heidenreich8 with hammered high purity aluminum, of P. B. Hirsch and collaborators7,8 with cold worked polycrystalline aluminum, copper, nickel, iron, gold, etc., and of Warren and Averbach9 with a rolled copper plus 2 pct Si single crystal. In addition to the existence of slightly disoriented sub-grains, the cumulative evidence from these investigations also shows that in the cold worked condition the subgrains themselves are severely strained. With regard to the early stages of annealing, Heiden-reich's results indicate that within the subarains of hammered high purity aluminum the strain gradually disappears, without discernible migration of the subboundaries. This recovery process presumably accounts for the major portion of the energy release

Jan 1, 1953

By John Wulff

In a previous paper Burwell and Wulff1 have shown by electron diffraction studies that allotropic transformations can be induced in 18-8 stainless steel by polishing to a depth of about 5 X 10-5 cm. The development of a successful etching technique, which removes accountable amounts of metal from the surface without pitting and without changing the root-mean-square profile as measured with an Abbot pro-filometer, led to the application of the whole technique and material to an investigation of various mechanical methods of surface preparation, such as grinding, lapping, superfinishing and cold-rolling. Ideally suited to such a study is 18-8 of low carbon and nitrogen content. The material can be heat-treated to produce a coarse-grained single-phase structure. On cold deformation there occurs not only a reduction in grain size but, at regions of maximum stress, a change of face-centered material to body-centered material, provided the metal is worked below about 200°C. When worked between 200"about and 415°C., diffraction studies evidence a reduction in grain size without the appearance of any new body-centered ferrite. Ferrite, which can be referred also to strains induced by carbide precipitation, is evident when the material is worked at temperatures between 4150 and 800°C. Stainless steel is advantageous because the usual surface-finishing operations do not readily oxidize it to any appreciable depth. In order to produce detectable oxide films on the surface of austenitic 18-8 in a time equivalent to that required to produce, for example, a fine ground finish on 1/2 sq. in., the sample must be held in a furnace or oxygen stream above 600°C. By using longer heating times, it is possible to achieve measurable oxide films on samples , whose surface temperatures exceed only about 250°C. Experimental Procedure The apparatus, material, and technique described in the previous paper1 were employed in this investigation. Samples of 18-8, I by I cm. by 4 mm., were carefully annealed in the austenitic range to produce a coarse-grained structure. They were then quenched and pickled to remove scale, On a lapping machine of the Graton2 type, both sides of each sample were polished to a a of 1/6 a wave length of sodium D light. Thereafter they were electrolytically etched to remove at least 1 X 10-3 cm. of the surface, a depth that is well below that of any defermations induced by surface preparation. samples of this material, carefully mounted in steel holders, were then sent to various industrial organizations known for special finishing techniques. In the instrue ment shops at the Massachusetts Institute of Technology check samples were finished by the same methods, as far as they were available. Abbot profilometer3 readings Were made on all the samples, which were then carefully degreased in double distilled benzine and alcohol, dried in a hot-filtered air blast, and kept in a desiccator. SUC-

Jan 1, 1941

By John Wulff

In a previous paper Burwell and Wulff1 have shown by electron diffraction studies that allotropic transformations can be induced in 18-8 stainless steel by polishing to a depth of about 5 X 10-5 cm. The development of a successful etching technique, which removes accountable amounts of metal from the surface without pitting and without changing the root-mean-square profile as measured with an Abbot pro-filometer, led to the application of the whole technique and material to an investigation of various mechanical methods of surface preparation, such as grinding, lapping, superfinishing and cold-rolling. Ideally suited to such a study is 18-8 of low carbon and nitrogen content. The material can be heat-treated to produce a coarse-grained single-phase structure. On cold deformation there occurs not only a reduction in grain size but, at regions of maximum stress, a change of face-centered material to body-centered material, provided the metal is worked below about 200°C. When worked between 200"about and 415°C., diffraction studies evidence a reduction in grain size without the appearance of any new body-centered ferrite. Ferrite, which can be referred also to strains induced by carbide precipitation, is evident when the material is worked at temperatures between 4150 and 800°C. Stainless steel is advantageous because the usual surface-finishing operations do not readily oxidize it to any appreciable depth. In order to produce detectable oxide films on the surface of austenitic 18-8 in a time equivalent to that required to produce, for example, a fine ground finish on 1/2 sq. in., the sample must be held in a furnace or oxygen stream above 600°C. By using longer heating times, it is possible to achieve measurable oxide films on samples , whose surface temperatures exceed only about 250°C. Experimental Procedure The apparatus, material, and technique described in the previous paper1 were employed in this investigation. Samples of 18-8, I by I cm. by 4 mm., were carefully annealed in the austenitic range to produce a coarse-grained structure. They were then quenched and pickled to remove scale, On a lapping machine of the Graton2 type, both sides of each sample were polished to a a of 1/6 a wave length of sodium D light. Thereafter they were electrolytically etched to remove at least 1 X 10-3 cm. of the surface, a depth that is well below that of any defermations induced by surface preparation. samples of this material, carefully mounted in steel holders, were then sent to various industrial organizations known for special finishing techniques. In the instrue ment shops at the Massachusetts Institute of Technology check samples were finished by the same methods, as far as they were available. Abbot profilometer3 readings Were made on all the samples, which were then carefully degreased in double distilled benzine and alcohol, dried in a hot-filtered air blast, and kept in a desiccator. SUC-

Jan 1, 1941

The Library of the above-named Societies is open from 9 A.M. to 10 P.M. on all week-days, except holidays, from September 1 to June 30, and from 9 A.M. to 6 P.M. during July and August. The Library contains about 55,000 volumes, including sets of technical periodicals and the publications of scientific and technical societies. Members of the Institute, with few exceptions, are forced to spend a portion of their tine in localities isolated from sources of information. To these the Library can render valuable service through correspondence; letters requesting information will receive special attention. The Library is prepared to furnish references and copies of articles on mining and metallurgical subjects; to determine the existence of mining maps, and to furnish general information as to the geology and mineral resources of all countries. All communications should be made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will -be saved, and the information will be sent more promptly and in more usable shape. The members of the Institute can be of service to the Library by forwarding copies of mining reports, maps privately issued, and similar material, which will be classified, indexed, and made available to other members. Suggestions for additions to the Library, either by purchase or personal solicitation as gifts, will be welcomed. It is hoped that members while in the city will use the Library freely, and assurance is given that most careful service will be rendered to them.

Jan 5, 1915

The Library of the above-named Societies is open from 9 A.M. to 9 P.M. on all week-days, except holidays, from September 1 to June 30, and from 9 A.M. to 6 P.M. during July and August. The Library contains about 55,000 volumes, including sets of technical periodicals and the publications of scientific and technical societies. Members of the Institute, with few exceptions, are forced to spend a portion of their time in localities isolated from sources of information. To these the Library can render valuable service through correspondence; letters requesting information will receive special attention. The Library is prepared to furnish references and copies of articles on mining and metallurgical subjects; to determine the existence of mining-maps, and to furnish general information as to the geology and mineral resources of all countries. All communications should be made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape. The members of the Institute can be of service to the Library by forwarding copies of mining-reports, maps privately issued, and similar material, which will be classified, indexed, and made available to other members. Suggestions for additions to the Library, either by purchase or personal solicitation as gifts, will be welcomed. It is hoped that members while in the city will use the Library freely, and assurance is given that most careful service will be rendered to them. .

Jan 11, 1913

The Library of the above-named Societies is open from 9 A.M. to 10 P.M. on all week-days, except holidays, from September 1 to June 30, and from 9 A.M. to 6 P.M. during July and August. The Library contains about 55,000 volumes, including sets of technical periodicals and the publications of scientific and technical societies. Members of the Institute, with few exceptions, are forced to spend a portion of their time in localities isolated from sources of information. To these the Library can render valuable service through correspondence; letters requesting information will receive special attention. The Library is prepared to furnish references and copies of articles on mining and metallurgical subjects; to determine the existence of mining maps, and to furnish general information as to the geology and mineral resources of all countries. All communications should be made as definite as possible so that the information received may be what is desired and not, include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape. The members of the Institute can be of service to the Library by forwarding copies of mining reports, maps privately issued, and similar material, which will be classified, indexed, and made available to other members. Suggestions for additions to the Library, either by purchase or personal solicitation as gifts, will be welcomed. It is hoped that members while in the city will use the Library freely, and assurance is given that most careful service will be rendered to them.

Jan 9, 1915

By Richard R. Zupp, David A. Stevenson

A theoretical treatment of austenitic Fe-C-Z solutions (where Z represents a substitutional solute) was developed by extending a solution model which was previously applied to austenitic Fe-C alloys. The model assumes that each carbon atom in the solution excludes H interstitial sites from occupancy by other carbon atoms rmd thai otherwise the assembly of carbon atoms is equivalent to a modified Langmuir lattice gas. The results of the treatment provide theoretical justification for a phenomenological expression previously developed to represent the influence of substitutional solutes on the thernlodynamics of carbon in austenitic Fe-C-Z alloys. The expression is: where Kz is a parameter which characterizes the Fe-C-Z system at a given temperature and Xz and xj are the concentrations of substitutional solute and interstitial carbon expressed as atom ratios. The parameter, Kz, was associated with the differ- A number of investigators have measured the influence of various substitutional solutes on the carbon activity in austenitic Fe-C-Z alloys, where Z represents any substitutional solute. Experimental information is available for alloys containing the following substitutional solutes: Mn,' Si,' Ni,2-5 CO,'-', Cr,5, 9-11 CU,4 Al,= v,11, 12 and Ti.13 This information is essential for studying many phenomena in Fe-C-Z alloys, particularly diffusion and diffusion-controlled phase transformations For example the pffprts nf various ence between the interaction energies between carbon atorns and host-lattice atoms in the Fe-C-Z solution and the corresponding energies for the Fe-C solution. The carbon activity in a ternary Fe-C-Z alloy, ac, was obtained in terms of the composition of the alloy and the single parameter, Kz: where y° is the Henry's law constant for the binary Fe-C solution. Both y° and H crm be determined from the data for Fe-C solutions, without recourse to any experimental data for Fe-C-Z solutions. The theoretical treatment was extended to alloys containing several substitutional solutes. By neglecting interactions between the substitutional solutes, an expression for the carbon activity in multicomponent alloys was obtained in terms of the Kz values characterizing ternary Fe-C-Z systems. substitutional solutes on the rate of pearlite growth is explained14 on the basis of their effects on carbon diffusion, which result from their influences on the carbon activity in the solid phases. In addition, recent studies have emphasized the dependence of the pro-eutectoid ferrite transformation15 and other diffusional processes in austenite16 on the influence of substitutional solutes on the carbon activity in austenite. They have indicated the need for suitable analytical expressions to represent such influences. The present authors previously developed general phenomenological expressions to represent the equilibrium partitioning of carbon between Fe-C alloys and Fe-C-Z alloys.'2 The expressions are applicable to all the austenitic Fe-C-Z alloys for which experimental data are available, and are sufficiently simple to recommend their general application. For alloys in

Jan 1, 1969

By S. F. Ravitz

IN his excellent book on the Principles of Flotation, Wark' makes the following significant statement concerning the theory of flotation: Two questions of first-rate importance must be considered . . . First, it must be decided whether the sulfide minerals require a collector in order that they may float, or whether as has been claimed, they possess an inherent floatability and need no collector. Second, it must be decided whether the xanthate type of collector can react with or be adsorbed by the unchanged sulfide minerals themselves, or whether, as many claim, reaction with the collector is dependent upon initial oxidation of the mineral surface. In the theory of flotation there are no two questions of greater importance than these. Ravitz and Porter' presented evidence that galena can be floated without a collector, and even without any reagent, provided oxidation products are thoroughly removed from its surface. They found also that thoroughly cleaned galena floated faster when xanthate was used than when a frother alone or no reagent was used, and that, without a collector, the recovery decreased gradually upon exposure of the mineral to air. Their work, however, has met with considerable criticism. I(127).3-6 This paper is presented to answer the objections that have been raised, and to present additional data that confirm their results. EXPERIMENTAL PROCEDURE The apparatus used to provide oxygen-free conditions for flotation has been described in detail by Ravitz and Porter. An atmosphere of purified nitrogen was maintained within the apparatus; all water and solutions used were freed of dissolved air, and could be transferred where desired by the use of nitrogen pressure; nitrogen was used as the gaseous medium for flotation. The flotation cell was essentially a glass cylinder 15 cm. long and 4.6 cm. in diameter. Near the bottom was sealed a fritted glass filter, which broke up the gas into small bubbles, and 6 cm. above this filter was a side arm through which the froth overflowed. The pulp was agitated by a glass impeller, which entered the cell through a mercury seal. For each test 17 grams of galena and 75 ml. of water were placed in the cell, after which the speed of the impeller and the rate of gas flow were adjusted. Water was added gradually during the test to keep the froth level at the proper height. The mineral was prepared and cleaned in the following manner. Exceptionally pure galena was crushed by hand on a clean bucking board, screened to - 150+ 200 mesh, and deslimed on a zoo-mesh sieve with a fine spray of water. It was then boiled on a hot plate for a number of hours with several changes of the desired cleaning solution, after which both the solution and the mineral were placed in the "mineral flask" of the apparatus. The cleaning solution was drained off, and the mineral was boiled with oxygen-free water

Jan 1, 1940

By L. L. McMurray

ILMENITE is the most important raw material for manufacture of titanium dioxide.1 Industrially, several other products are made from ilmenite, the most important of which are: ferrotitanium, ferro carbon-titanium, copper-titanium, titanium carbide and titanium nitride. The production of titanium metal is still in the laboratory stage because of the difficulty of extraction and as yet no important application for the metal has been found. Ilmenite has received considerable attention as an industrial raw material. Imports of ilmenite concentrates for the first nine months of 1941 were 156,737 short tons, the chief source being Travancore, India.2 Domestic production of ilmenite has here-tofore been confined to Amherst and Nelson Counties, Virginia, where a complex rutile, ilmenite, and apatite ore is mined and treated to utilize all three of these minerals. A recent report3 has described development of the large titaniferous magnetite ore body at Tahawas, New York, where it is expected that 800 tons of ilmenite concentrates, containing 48 per cent Ti02 will be produced daily. Additional domestic production is expected from a large ilmenite deposit recently opened in Caldwell County, North Carolina. Flotation tests indicate that a high-grade concentrate containing 53 per cent Ti02 can be made from the North Carolina ore. Prospecting of domestic ores in other areas has been reported.4 It appears that increased domestic production of ilmenite may well save considerable shipping space so vitally needed in these times. The composition and chemical structure of pure ilmenite is given by Dana as: FeO, TiO2; Ti, 31.6 per cent, Fe, 36.8 per cent, 02, 31.6 per cent. This composition is variable in that some iron or titanium may be replaced, giving a variable iron-titanium ratio. As an example, the iron-titanium weight ratio of ilmenite in Caldwell County, North Carolina, has been determined to be 0.94 (using 97.1 per cent ilmenite concentrate obtained by heavy liquids on minus 150-mesh ore) compared with theoretical 1.16. No rutile was noted in this ore to account for the low value. This North Carolina ore is free of magnetite, which is a common associate of ilmenite ores. In view of a large potential production from North Carolina, the Tennessee Valley Authority conducted a study of methods of concentration of that ore, of which the results are reported herein. THE ORE Five samples of ore were taken from the deposit at various exposed locations and were mixed for the study and testing. An attempt was made to proportion the amount of weathered and unweathered portions in making the composite sample, so as to approximate actual operating conditions. An examination of representative specimens of the sample showed the following general facts: I. The black mineral comprising nearly 70 per cent of the ore is ilmenite.

Jan 1, 1944

By H. R. Hendricks

The ore of the Iron King mine, being very hard and having a very fine crystalline structure, presents many problems in milling that are not present in ordinary lead-zinc ores. This very fine crystallization causes much interlocking of minerals and is most prevalent between the gold and pyrite and the sphalerite and pyrite. The recovery of gold is extremely important in the economic value of the ore and therefore constitutes a large part of the metallurgical problem to be solved. All of the gold is free but it has not been observed in any of the mill products except under very high magnification. Some of the gold is tarnished, and this condition also makes recovery difficult. The gold values have been determined to be highest in association with chalcopyrite and arsenopyrite. The silver occurs mostly in association with galena and tennantite. A small amount of native silver has also been observed occasionally. The galena, being softer than the other minerals, frees much better in grinding. Some oxidation of galena is present in the ore, as the non-sulphide lead content amounts to approximately 10 pct of the total lead. Some oxidation of sphalerite is also present in the ore. Microscopic examination of the zinc concentrate shows many grains in the minus 325-mesh to be half pyrite, together with the fact that some of the zinc is marmatite, makes production of a high-grade zinc concentrate very difficult unless recovery is sacrificed. In the grinding, it has been determined that the flotation feed must be maintained at 85 pet minus 200-mesh to free the minerals sufficiently to make the best economic recoveries. Table I illustrates the effect of fine grinding. It shows that the bulk of the recovered minerals is in the minus 325-mesh size and is the part of the minerals that is more readily freed. The pyrite concentrate is not given in the table because it contains practically no minus 325-mesh. Development of Present Flowsheet and Milling Practice The first milling operation started in 1938, with a mill capacity of 140 tons daily, producing a bulk gold-silver-lead concentrate. After several stages of expansion and changes of the mill flowsheet, the mill is currently treating 380 tons of ore daily and three separate concentrates are produced. In order of their importance and value, these are: (I) lead concentrate, (2) zinc concentrate and (3) pyrite concentrate. The present average grade of mill heads is: gold 0.11 oz, silver 4.00 oz, lead 2.50 pet, zinc 7.60 pct, copper 0.22 pct, iron 22 pct and 30 pct insolubles. Specific gravity of the ore is 3.8. During the period when bulk flotation mas practiced, the flowsheet was very simple. The ore was ground fine enough to liberate as much gold, silver and lead as possible. Necessary collectors and frothers were added in sufficient quantity

Jan 1, 1949

By Stanley J. LeFond, Neal Davis

Drilling an oil well or most other types of drilling or coring is no longer a simple and uncomplicated operation. Drilling today at depths which exceed 9144 m (30,000 ft) is hazardous and requires personnel with long and varied experience in drilling. It also requires extensive experience and knowledge in the use of materials which are added to the drilling fluid or "mud," more often than not materials utilizing an industrial mineral. The drilling fluid can vary from a simple mixture of water and "mud" to a very sophisticated, scientifically compounded drilling fluid. Industrial Minerals Used in Drilling Fluids Industrial minerals which are commonly used in oilwell drilling and completion are listed in Table 1. The most important minerals, determined by sales, are bentonite and barite. The other minerals listed are either used to achieve a specific purpose or are used regularly but in limited quantities. The main suppliers of drilling fluids internationally are Magcobar Div., Dresser Industries, Inc.; Baroid Div., National Lead Co.; IMC Drilling Mud Co., (a subsidiary of international Minerals and Chemicals Corp. and Halliburton Co.); and Milchem, a division of Baker Industries. Most of the industrial minerals are found in North America, with barite mines and processing plants located in Nevada, Arkansas, Missouri, and Arizona, and bentonite mines near Graybull, WY. Other mines, such as those in Nova Scotia, are capable of shipping to South America and to the European and Middle East countries. Most of the materials processed by any of the suppliers must conform to specifications set by the American Petroleum Institute (API) or the Oil Companies Material Organization (OCMA). These specifications provide for uniform physical and chemical properties of the materials to be sold on the open market. Function of Drilling Fluids In the early days of rotary drilling, the primary function of drilling fluids was to bring the cuttings from the bottom of the hole to the surface. Today it is recognized the drilling fluid has at least ten important functions: 1) To remove the cuttings from the bottom of the hole and carry them to the surface. 2) To cool and lubricate the drill string and drill bit. 3) To build an impermeable cake on the wall of the hole. 4) To control subsurface pressures. 5) To hold cuttings and weight material in suspension when circulation is interrupted. 6) To release sand and cuttings at the surface. 7) To support part of the weight of drill pipe and casing. 8) To reduce to a minimum any adverse effects upon the formation adjacent to the hole. 9) To insure maximum information about the formation penetrated. 10) To transmit hydraulic horsepower to the bit. In order to accomplish some or all of these functions while penetrating formations of various characteristics, several types of drilling fluids systems have been designed. Types of Drilling Muds There are two basic drilling fluid systems-water-base muds and oil-base muds. There is a wide variety of groups within these two main

Jan 1, 1983

By J. W. Marx

A method is given for predicting the complete gravity drainage characteristics of arbitrarily long columns from centrifuge drainage measurements on reconstituted core samples. Oil residuals corresponding to hundreds of years of normal gravity depletion can be obtained in a few hours on the centrifuge. The gravity flow rate at any stage of the depletion process may be determined from the time correlation derived, and experimentally checked, in this study. INTRODUCTION Apart from the original observations of Muskat et al1, research publications2,3,4 on the subject of gravity drainage have been largely concerned with establishing in detail the saturation, S as a function of the height, z, in a draining column at any given time, t. Some form of numerical integration must be employed to obtain production rates and cumulative production even when S(z, t) is known. Furthermore, the relevant experimental work has been concentrated on drainage of a single wetting liquid from unconsolidated media. Since oil production usually concerns the drainage of a partially wetting liquid from consolidated media, in the presence of connate water, and since it is unlikely that sufficient information exists to establish S(z, t) in detail for any natural reservoir, the published research work appears to be, at best, only qualitatively applicable to production problems. With this in mind, the present study was undertaken by the writer. Experiments were planned whose results would have two advantages over existing measurements: 1. Observations were to be made on specific reservoir rock, reconstituted with formation water and formation oil. This would reduce their generality, from the research viewpoint, but increase their utility for production purposes. 2. The measurements were to be self-integrating, i.e., the phenomena were to be described and interpreted in terms of cumulative results. THEORETICAL DEVELOPMENT It was commonly known that centrifuging a liquid bearing porous medium increases the drainage rates and minimizes capillary end effects. The specific problem lay in selecting an acceleration, a, such that the mean residual saturation of a model cylinder was equal to the residual saturation of an arbitrarily long prototype column when the latter was drained by earth gravity alone. The physical conditions required to permit a valid scaling of model drainage time, tm with prototype drainage time, t, may be stated as follows: (a) At t = tm = O, So = Smo; (b) At t = tm? 8 Sr. = Smr.; (c) For all intermediate values of t and dS/dt=dsm/dtm whenever S = Sm; (d) S(z) = Sm(z) = a constant when t = tm = 0. 1 Here S = T I S(z)dz, where h is the length of the « Jo cylindrical column being drained and the subscripts S,Sm, and refer to model, initial, and residual systems, respectively. The first three conditions mean, simply, that an 3 vs t plot will be numerically identical with an S, vs t, plot,

Jan 1, 1957

By C. Williams, D. V. Carter

During 1943 five oil fields and two gas-condensate fields were discovered in the East and East Central Texas district. The New Hope field, discovered by Tide Water-Seaboard in Franklin County, is the most important oil discovery since the Hawkins field in 1940. At the close of the year two oil sands were producing and two additional oil sands were being tested. The gas-condensate fields of Appleby in Nacog-doches County and the Stewards Mill field in Freestone County had only one producing well each. The Carthage field was extended 3 miles north and 4 miles west. Another well that was testing at the year end indicated a probable eastward extension of several miles. The Quitman field, in Wood County, was the most active from the standpoint of drilling operations. Approximately 48 wells were complcted during the year. The second and third most active fields were Hawkins field, Wood County, and Kildare field, Cass County, respectively. Wartime restrictions of material, together with manpower shortage and Federal spacing regulations, reduced the number of oil and gas-well completions from 265 in I942 to 171 in 1943. This represents a drop of 35 percent, or approximately 1/3, enough to replace the 531 producing wells abandoned in the district during the year. No changes were made in the price of crude oil in the district in 1943. The district produced 177,652,940 bbl. of condensate and oil during 1943. This represents an increase of approximately 11 per cent compared with the previous year. The East Texas field, which is the largest and most important field in the district, had an annual production of 128,568,647 bbl. of oil, which is approximately 6.5 per cent more than the previous year, and represents 72 per cent of the district's production of condensate and oil for the year. The district had an estimated basic daily allowable of approximately 509,000 bbl. of oil on Dec. 31, 1943. The entire district produced approximately 30 pcr cent of the state's production for the year 1943. The Hawkins field, Wood County, was operated 271 days during the year and with an average daily production of approximately 52,488 bbl. for the year. This field, which is the second largest in the district, produced 14,224,164 bbl, of oil during the year. Changes in annual production in certain fields in the district can be attributed to their ability to produce at higher rates, the demand, and transportation facilities in the war effort. The East Texas field showed an over-all decrease in reservoir pressure of 8.30 lb. during the year. Indications were that through the first quarter of 1944 the return of salt water to the reservoir was having a beneficial effect. It is hoped that, as more and more water is returned to the reser-

Jan 1, 1944

By D. V. Carter, C. Williams

During 1943 five oil fields and two gas-condensate fields were discovered in the East and East Central Texas district. The New Hope field, discovered by Tide Water-Seaboard in Franklin County, is the most important oil discovery since the Hawkins field in 1940. At the close of the year two oil sands were producing and two additional oil sands were being tested. The gas-condensate fields of Appleby in Nacog-doches County and the Stewards Mill field in Freestone County had only one producing well each. The Carthage field was extended 3 miles north and 4 miles west. Another well that was testing at the year end indicated a probable eastward extension of several miles. The Quitman field, in Wood County, was the most active from the standpoint of drilling operations. Approximately 48 wells were complcted during the year. The second and third most active fields were Hawkins field, Wood County, and Kildare field, Cass County, respectively. Wartime restrictions of material, together with manpower shortage and Federal spacing regulations, reduced the number of oil and gas-well completions from 265 in I942 to 171 in 1943. This represents a drop of 35 percent, or approximately 1/3, enough to replace the 531 producing wells abandoned in the district during the year. No changes were made in the price of crude oil in the district in 1943. The district produced 177,652,940 bbl. of condensate and oil during 1943. This represents an increase of approximately 11 per cent compared with the previous year. The East Texas field, which is the largest and most important field in the district, had an annual production of 128,568,647 bbl. of oil, which is approximately 6.5 per cent more than the previous year, and represents 72 per cent of the district's production of condensate and oil for the year. The district had an estimated basic daily allowable of approximately 509,000 bbl. of oil on Dec. 31, 1943. The entire district produced approximately 30 pcr cent of the state's production for the year 1943. The Hawkins field, Wood County, was operated 271 days during the year and with an average daily production of approximately 52,488 bbl. for the year. This field, which is the second largest in the district, produced 14,224,164 bbl, of oil during the year. Changes in annual production in certain fields in the district can be attributed to their ability to produce at higher rates, the demand, and transportation facilities in the war effort. The East Texas field showed an over-all decrease in reservoir pressure of 8.30 lb. during the year. Indications were that through the first quarter of 1944 the return of salt water to the reservoir was having a beneficial effect. It is hoped that, as more and more water is returned to the reser-

Jan 1, 1944

By Cyril Stanley Smith

ON the 6th of February 1684, Dr. Martin Lister mentioned at a meeting of the Royal Society1 that "brass is magnetical," and promised to give an account of that assertion at some other time. He repeated his promise but never fulfilled it, and it was left for William Arderon2 to show, in 1958, that brass could be made magnetic by hammering and that it would retain polarity after magnetizing. Twenty-seven years later Cavallo3,4 examined the matter in great detail. Working with cast calamine brass, he showed that it could be made magnetic by hammering and nonmagnetic by subsequent annealing at a red heat. He found that annealing at a very high temperature caused the samples to lose their magnetic quality permanently, even after subsequent cold-working, but that remelting and cold-working restored it. He encountered some samples of brass that could not be rendered magnetic by any treatment. Experiments in which these were remelted with iron additions gave negative results, and Cavallo concluded that iron impurity was not the cause of the magnetism. He worked with 50-grain (3-gram) samples melted under the blowpipe, hence cooled very quickly. Bennet5 made whole crucible charges from copper and zinc, and found the resulting brass ingots to be magnetic only when iron had been added and then only after cold-working. All these observations applied to material in the cast condition, in which coring would produce a continuous spectrum of composition and cooling would result in varying degrees of precipitation. This knowledge of the subject seems to have been forgotten in the nineteenth century. The older brass was made by the calamine process and frequently contained iron in amounts of 0.5 per cent or more, absorbed from the impure ore with which the copper and charcoal were heated in making the brass. When metallic zinc became available in commercial quantities, calamine brass gradually disappeared, and with it the knowledge of its curious magnetic properties. Only when sensitive apparatus replaced the compass needle of the earlier investigators could the effects be detected in relatively pure metal. The effect of cold-working in inducing ferromagnetism was rediscovered by Bitters in 1930 in a sample of impure copper, and this was confirmed by Lowance and Constant,9 Honda and Shimizu, 10,11 and others. In the same year, Tammann and Oelsen12 showed that copper-rich copper-iron alloys after certain heat-treatments could be rendered ferromagnetic or made more strongly ferromagnetic by cold-rolling. Kussman and Seeman13 showed that the change of susceptibility of relatively pure copper on cold-working was associated with the iron content, and concluded that actual precipitation of iron was caused by cold-working, which is a satisfactory theory until one considers the improbably high rate of diffusion that this would involve. When studying precipitation phenomena in

Jan 1, 1941

By Ronald J. Roman

Research pertaining to flow of solutions in leach dumps has generally been neglected. This technical note proposes a method for evaluating the flow patterns and incorporating the results into dump-leaching models. Three dump-leaching models1-3 have been proposed to scale up laboratory test data to expected field results. These models are based on the same physical picture in a dump and differ only in the importance of diffusion or surface chemical reaction rate. Selection of this rate-controlling phenomemon is based on type of ore (sulfide or oxide), physical dimensions of the particles being leached, and the leach heap itself. All three models are applicable to specific types of operations. The models are similar in the use of a size distribution analysis for the dump material and the assumption that the leach solution flows around each particle. Transport of the leaching agent to the interior of the particle takes place by diffusion [(Fig. 1)]. However, normal dumps are of a higher bulk density than the material in a laboratory column used to generate the scale up data. How does this difference in bulk density affect the scale up equations? Increasing the bulk density can be expected to give more particle-to-particle contact; therefore, individual particles will be blinded by each other. As blinding increases with bulk density increase, the particles will behave like larger particles with a coarser apparent size distribution. The extreme will occur when the bulk density reaches that of the undisturbed rock, the entire dump behaving as a single particle with the dimensions of the heap itself. Harris4 alluded to this phenomenon in his paper. An alternative method of describing the same phenomemon is to consider the flow paths of the solution. At high bulk densities leach solution no longer surrounds each particle, but flow paths are separated by several particles and channeling is said to take place. Instead of the particle radius being the maximum distance through which the leaching agent must diffuse, the maximum distance is half the separation distance of the solution flow path. Particle size distribution must then be replaced in the models by the concept of channel separation distribution. Like size distribution, channel separation distribution specifies the cumulative percentage of the rock in the dump situated less than a specified distance from a solution channel. Thus, [ ] Distribution of the solution channels is a function of how the dump was built (among other things), and therefore it cannot be determined in the laboratory. Accordingly, it becomes necessary to determine a range for d and a in existing operations or measuring these parameters before leaching starts. Howard5 gives a clue to one possible technique of measuring solution channel distributions. When his paper was published little was known about the phenomemon of leaching; the importance of this type of data was not recognized. [Fig. 2] is a Y-Y log for one hole drilled

Jan 1, 1978

By Paul A. Beck

IN several recent investigations1 ' considerable evidence was accumulated to show the predominance in various face-centered cubic metals of a certain relative orientation, corresponding to a rotation of 30" to, 40" around a [111] axis, between a matrix with a strong single orientation texture and grains growing in this matrix." This relative orientation was found to occur both in recrystallization and in coarsening, "secondary recrystallization", so that one is inclined to look for an explanation applicable in both cases. The abundance of growing grains in the described orientations proves that suitable "nuclei" are present in the matrix material and that they have the capacity to grow. The scarcity of growing grains in other orientations may be explained in one 'of two ways. Either the number of nuclei or the rate of growth must decrease strongly for orientations deviating from that predominating among the growing grains, Fig. 1. Both the "oriented nucleation" and the "oriented growth" theory found support in the literature. Because the frequency of nuclei as a function of orientation is in most instances not amenable to direct experimental investigation, a definitive decision is difficult to achieve. However, it is now known with great certainty that the rate of boundary migration is strongly dependent on the relative orientation of the two grains meeting at the boundary and that the orientation favored by high boundary mobility closely corresponds to that predominating in most cases of recrystallization and coarsening. Thus, it was found that, in general, the mobility is very low for boundaries between grains of nearly identical orientation, or for coherent twin boundaries. On the other hand, the boundaries between two grains of a relative orientation correspending to a [1111 rotation of 30" to 40" have the highest mobility in face-centered cubic metals. If a large variety of nucleus orientations are produced grow- by means of a highly inhomogeneous local deformation, nuclei close to the above orientation are found to grow fastest.z4 In view of this evidence and of the fact that the preferred orientation relationship is the same in recrystallization and in coarsening, the oriented growth theory appears by far the more promising one. Since the origin of nuclei in primary recrystallization is certainly different from that in coarsening, the occurrence of the same orientation relationship in the two processes would be difficult to explain on the basis of oriented nucleation. other advantages of the oriented growth theory are its capability of accounting for the often observed sharpening of the texture in coarsening, and its suitability for explaining the role in the formation of the ''cube texture,, of the most important variables, such as the degree of rolling, the penultimate grain size, and the time and temperature of the last anneal: No similarly consistent explanation of all these effects has ever been offered in terms of oriented nucleation. An important problem in connection with the oriented growth theory is the following: In the ce-c entered system there are four [111] axes and

Jan 1, 1952

By H. R. Hendricks

THE ore of the Iron King Mine, being very hard and having a very fine crystalline structure, presents many problems in milling that are not present in ordinary lead-zinc ores. This very fine crystallization causes much interlocking of minerals and is most prevalent between the gold and pyrite and the sphalerite and pyrite. The recovery of gold is extremely important in the economic value of the ore and therefore constitutes a large part of the metallurgical problem to be solved. All of the gold is free but it has not been observed in any of the mill products except under very high magnification. Some of the gold is tarnished, and this condition also makes recovery difficult. The gold values have been determined to be highest in association with chalchopyrite and arsenopyrite. The silver occurs mostly in association with galena and tennantite. A small amount of native silver has also been observed occasionally. The galena, being softer than the other minerals, frees much better in grinding. Some oxidation of galena is present in the ore, as the nonsulphide lead content amounts to approximately 10 pct of the total lead. Some oxidation of sphalerite is also present in the ore. Microscopic examination of the zinc concentrate shows many grains in the minus 325-mesh to be half pyrite, together with the fact that some of the zinc is marmatite, makes production of a high-grade zinc concentrate very difficult unless recovery is sacrificed. In the grinding, it has been determined that the flotation feed must be maintained at 85 pct minus 200-mesh to free the minerals sufficiently to make the best economic recoveries. Table I illustrates the effect of fine grinding. It shows that the bulk of the recovered minerals is in the minus 325-mesh size and is the part of the minerals that is more readily freed. The pyrite concentrate is not given in the table because it contains practically no minus 325-mesh. DEVELOPMENT OF PRESENT FLOWSHEET AND MILLING PRACTICE The first milling operation started in 1938, with a mill capacity of 140 tons daily, producing a bulk gold-silver-lead concentrate. After several stages of expansion and changes of the mill flowsheet, the mill is currently treating 380 tons of ore daily and three separate concentrates are produced. In order of their importance and value, these are: (1) lead concentrate, (2) zinc concentrate and (3) pyrite concentrate. The present average grade of mill heads is: gold 0.11 oz, silver 4.00 oz, lead 2.50 pct, zinc 7.60 pct, copper 0.22 pct, iron 22 pet and 30 pct insolubles. Specific gravity of the ore is 3.8. During the period when bulk flotation was practiced, the flowsheet was very simple. The ore was ground fine enough to liberate as much gold, silver and lead as possible. Necessary collectors and frothers were added in sufficient quantity

Jan 1, 1947

By J. H. Frye, J. W. Caum

ONE of the most important methods of increasing the hardness of metals is alloying. In spite of the widespread use of alloys, the fundamental mechanism of alloy hardening is little understood. This is true even of the simplest form of alloy, the primary substitutional solid solution in which solute atoms substitute for solvent atoms at random in the crystal lattice of the latter. A fundamental understanding of the mechanism of solid-solution hardening would be important, both because of the widespread use of alloys of this type and because of the light that might be thrown on the mechanism of hardening in more complicated alloys. The present investigation covers the hardness of primary substitutional solid solutions of zinc, gallium,, germanium; and arsenic in copper. All of these are B subgroup elements from the third period of the periodic table. Cu, Zn, Ga, Ge, and As are in groups I, II, III, IV, and V, respectively and lie just to the right of the transition elements. Because of their cost, it is unlikely that Ga-Cu and Ge-Cu solutions will ever be of commercial importance, but the intent of this study has been to discover some of the fundamentals of solid-solution hardening and it has been demonstrated that such a study is far more likely to be fruitful if alloys are made up on the basis of position of the constituent elements in the periodic table than if commercially important alloys are used. Many investigations have. been made of the hardness of substitutional solid solutions, but lack of attention to purity of the metals, infrequent grain-size control, and the use of varying testing techniques have virtually invalidated any comparisons. The purpose of most investigations has been to solve immediate problems and not to solve the primary problem: Why do solid solutions usually have a greater hardness than pure metals? PREVIOUS WORK Theories have been advanced to account for the hardness of solid solutions,, but relatively little experimental work has been done. Perhaps the first experimental work of merit was that of Norbury1 on copper alloys. He showed that for several alloys there was a correspondence between the hardness of one atomic per cent solutions and atomic volume of the solutions. More recently Brick, Martin, and Angier2 have investigated the effect of various solute elements on the hardness of copper. They concluded that the hardening effect of these solutes depended "primarily on the difference in atomic volume of solute and solvent or, relatedly, upon the parameter, change of the solvent or the extent of solid solubility." They also observed the effect of these elements on hardness and texture developed by rolling and by annealing of rolled material. Austin3 examined the hardness and response to heat-treatment of various iron solid solutions. Frye and Hume-Rothery4 measured the hardness of a number of silver solid solutions containing approximately

Jan 1, 1943