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Established as a Division November 17, 1948 R Schuhmann, Jr, Chairman A E Lee, Jr, Past Chairman R C Cole, Chairman-Elect H W St Clair, VIce-Chairman, '61 , Vice-Chairman, '62 Paul Queneau, Vice-Chairman, '63 T D Jones, Treasurer R W Shearman, Secretary AIME, 29 West 39th Street New York 18, N Y

Jan 1, 1960

By O. N. Carlson, S. A. Bradford

Discontinuous yielding in tensile tests was observed in V-O alloys in the temperature ranges of 150° to 175°C and also 350° to 400°C. The magnitude and intensity of the serrations were found to vary considerably with oxygen content. Maxima were observed in tensile and yield strengths and in the strain-hardening coefficient at the higher temperature only. The strain rate sensitivity was observed to be negative between 150° and 400°C. THIS investigation was undertaken to study the effect of oxygen on the tensile properties of iodide vanadium in the temperature range of 25o to 450°C. Brown1 observed an increase in strength between room temperature and 400°C in vanadium metal, and found that oxygen and nitrogen had a rather pronounced effect on the strength and ductility. A maximum in the tensile strength was observed by Rostoker et al.2 near 300oC and by Pugh3 around 450°C for calcium-reduced vanadium. Pugh also found a maximum in the yield strength and in the strain-hardening exponent, and minima in the elongation and strain rate sensitivity at the same temperature. Eustice and Carlson4 reported the appearance of serrations in the stress-strain curves between 140° and 180°C in iodide vanadium containing 600 ppm O. These anomalies in the mechanical properties indicate that strain aging occurs in vanadium, but the impurity or impurities responsible for the above-mentioned effects have not been identified. The phenomenon of strain aging is usually characterized by the return of the yield point after interruption of a strength test. In the temperature range where strain aging occurs, the yield and tensile strengths attain maximum values, elongation and strain rate sensitivity exhibit minima, and discontinuous yielding is generally observed in the stress-strain curve. Cottrell5, 6 has postulated that strain aging is due to the migration of solute atoms to dislocation sites to produce locking after the dislocations have broken free from their impurity atmospheres during the initial yielding. At the strain-aging temperature the process is a dynamic one in which the solute impurity atoms diffuse to the vicinity of the moving disloca- tion producing "locking" which gives rise to maxima in the tensile strength and serrations in the elongation curves. Cottrel17 has noted that discontinuous yielding in iron occurs when the diffusion coefficient of nitrogen, D, and the strain rate, i, are related by D = 10-9 €. EXPERTMENTAL PROCEDURE The vanadium metal employed in this study was prepared by the iodide refining process as described by Carlson and owen.8 A representative analysis of the vanadium used in this investigation was: 150 ppm O, <5 ppm N, <1 ppm H, 150 ppm C, 150 ppm Fe, 70 ppm Cr, <50 ppm Si, 30ppm Cu, 20 ppm Ni, <20 ppm Ca, <20 ppm Mg and <20 ppm Ti. Alloys containing from 200 to 1800 ppm O, all of which lie in the solid solution range of the V-O system, were prepared by arc melting vanadium together with portions of a high-oxygen master alloy. The master alloy was prepared by tamping pure V2O5 into holes drilled in a vanadium ingot and arc melting this five or six times in an inert gas atmosphere, inverting the button between each melting step. The oxygen content of the master alloy was then determined by vacuum fusion analysis. Vanadium containing less than 150 ppm O was prepared in the following manner. A bar of iodide vanadium was deoxidized by sealing it in a tantalum crucible with a few grams of high-purity calcium. This was held at 1100°C for 4 days to allow time for the oxygen to diffuse to the surface and to react with the calcium vapors. The calcium oxide product was later dissolved from the surface of the bar with dilute acetic acid. In this way vanadium containing from 20 to 50 ppm O was prepared. Sample Preparation. The are-melted ingots were cold swaged into 3/16-in. diam rods and these were machined into cylindrical tensile specimens with a reduced section of 1.00-in. length and 0.120-in. diam. The test specimens were annealed for 4 hr at 900°C in a dynamic vacuum of mm of Hg to remove hydrogen from the metal. This recrystal-lization treatment produced a uniformly fine-grained structure with a mean grain size of approximately 0.06-mm diam. The oxygen contents reported in this paper were determined by a vacuum fusion analysis of the tensile specimens after testing. Analyses for other interstitial or metallic impurities showed no significant changes from that of the original material. Tension Tests. Tension tests were performed on a screw-driven tensile machine at a constant cross-head speed of 0.01 in. per min. Tests at elevated temperatures were carried out by heating the

Jan 1, 1962

By Robert Sisselman

Central Sweden&apos;s Grängesberg underground iron ore mine, which accounts for more than three million tons of pellet product annually, is experiencing a major changeover to continuous block-caving. The newly-adopted method, complete with a total revamping of mining equipment, will be fully operational by 1975. For the past 15 years, Sweden&apos;s Grängesberg mine has been mined using two different methods. Those ore thicknesses of 117 ft or greater (they comprise about 70% of the total area) are worked by block-caving techniques with cross-cutting carried out on each 195-ft working level, and loading at the foot wall on each 58-78-ft level. Sub-level caving is carried out in all ore sections less than 117 ft thick.

Jan 1, 1974

By E. H. Fahmy, L. C. Uren

During recent years, oil producers have observed with interest the practical success which has attended the application of water as a medium for displacement of oil from its reservoir sands in the Bradford field of northern Pennsylvania and southern New York. Here, according to various authorities, additional recoveries of frorn 2,000 to 12,000 bhl. of oil per acre have heen secured by this method, after ordinary flowing and pumping. rnethods of production had practically reached the lower limit of economic operation. Notwithstanding the success which has attended the practical use of the flooding process in the Bradford field, oil producers in other regions are skeptical of its value when applied under physical conditions differing markedly from those which characterizc the Bradford field. Its usc would probably he construed as illegal in most of the oil-producing states. This general relnctance on the part of oil producers in other regions to accept the flooding process is due in large part to lack of infor-n~ation regarding the factors that influence its operation and efficiency. With the purpose of clarifying to some extent the issues involved, and of determining when the flooding proccess may or may not beeffee-tivcly ernployed, the writers have conducted a serics of laboratory exper-imentments under carefully controlled conditions, designed to indicate, the influence of various physical, chemical arid lithologic factors. These experments have not been conducted under conditions identical with those which exist at depths far below the earth&apos;s surface, so that direct quantitative comparisons with field results are not justified, hut it is believed that the experimental results at least warrant qualitative inter-pretations that may he applied to field conditions. The methods employed in the conduct of these experiments are briefly explained, and the results, together with the conclusions based thereon, arc presented. FactoRs Influencing Displacement of Oil froM SaNdS by WAteR- flooding Before presenting the experimental data, it, will he desirable to con-sider the manner in which the residual oil is retained within the oil sand

Jan 1, 1928

By J. L. Shafer, Christopher L. Caenepeel, Martha L. White

Often an in situ leach is the only practical economic method for copper recovery from small low grade oxide deposits. The decision to develop a copper property by an in situ blast and leach is strongly dependent on ore grade, tonnage, hydrology, and the copper extraction and acid consumption rates. The inherent leachability of the ore will in part determine the desired amount of fracturing of the ore deposit by the blast in order to obtain a copper extraction rate that is economical. For the last several years Occidental Research Corp. (ORC), has undertaken a modest effort to address the question of how to best identify and determine the information necessary to predict and control the operation of an in situ leach for the economic recovery of copper. Modelling of the Leaching Process During the past 10 years the activity in the mathematical modelling of the leaching of copper sulfides in copper dumps and heaps has increased dramatically. The modelling of copper oxide leaching has not received as much attention. The acid leaching of non-sulfide copper minerals while chemically less complex, compared to sulfides, does generate a vertical acid concentration gradient in the ore heap being leached due to the acid-base nature of the reaction. This is generally not observed in sulfide deposits that are biologically active, due to the buffering action of opposing reactions involving the generation of sulfuric acid from sulfide minerals and acid consuming host rock. Thus, the objective of ORC &apos;s copper oxide modelling efforts is to determine the leaching parameters which will account for this vertical acid concentration gradient. Knowledge of this gradient will result in the correct choice of the feed acid concentration to the top of the ore dump or heap, such that the effluent will have the desired pH.

Jan 1, 1980

By L. S. Darken

IT has been known for sometime that in an ionic lattice, such as that of Ag2S or FeO, the migration velocity of the anion may differ markedly from that of the cation, the cation being usually the more mobile. It has been shown, for example, that during the formation of silver sulfide tarnish on silver, the tarnish layer grows principally by the motion of silver cations through an essentially stationary silver sulfide lattice. Similarly, the growth of wüstite scale on iron proceeds principally by motion of iron ions, this being accomplished with the aid of vacant iron lattice sites into which the iron may readily move. Likewise investigations of solid solutions of various salts show that there is usually considerable difference in the mobility of the different cations. Measurements of the mobility of various metals in liquid mercury indicate that the various metals move at different rates relative to the mercury. In view of the foregoing it seems reasonable to suppose that when any single phase solution is acted upon by a field, the atoms of different elements respond in different ways; in particular, that the force arising from a particular concentration gradient in a binary alloy would cause the atoms of one component to move with a drift velocity which is in general different from that of the atoms of the other component. The recent experiments of Smigelskas and Kirkendall1 support this viewpoint, since they found, in essence, that during diffusion in alpha brass zinc moves appreciably faster than copper. This was evidenced by the relative motion of inert molybdenum wires. Such a phenomenon is incompatible with the place interchange theory of diffusion proposed by several authors, most recently by Birchenall and Mehl.2 This theory has, however, also been questioned3.4 for other reasons, principally because of the high energy required for direct atomic interchange. The rather large difference between self-diffusivity, as determined by tracer technique, and mutual diffusivity, as determined with the aid of another element at low concentration, might also be interpreted as favoring the above idea; however, Birchenall and Mehl have pointed out that there is another possible interpretation of this difference; this is discussed later. A rather interesting and pertinent observation was made by Schwartz,5 who noticed that tungsten lamp filaments, heated by direct current, commonly fail by necking down in the region at the temperature gradient near the positive end, with a concomitant swelling at the corresponding position near the negative end. He introduces considerable auxiliary evidence to show that this phenomenon is occasioned by the motion of tungsten cations which migrate in the high temperature region from the positive end toward the negative end. The mechanism of this migration is not clearly understood. If, however, this experimental evidence be accepted, we are forced to conclude that alloying elements in the tungsten may migrate by the same or a similar mechanism, whatever it may be, at a greater or lesser rate, thus giving rise

Jan 1, 1948

By Alfred F. Beasley

The slags derived from the smelting of lead and copper ores are composed essentially of silicates. The problems arising from the smelting of these ores consequently involve the study of silicate fusions. In the absence of specific knowledge concerning the compounds occurring in slags, it has been the practice of metallurgists to treat them in terms of their total chemical composition. Slags have been classified as monosilicates, bisilicates, sesquisilicates, and subsilicates according to the relative amounts of oxygen in the acid and basic radicles of the hypothetical salt produced. While this has been a useful guide to metallurgists in computing the furnace charges, it falls far short of a basis for the scientific investigation of slags. In order to understand the nature of a slag as a whole it is necessary to learn the physical and chemical properties of the mineral compounds which go to make up that slag. The efficiency with which an ore is smelted in a furnace depends primarily on the physical properties of the compounds formed during the operation. When the melting points and fields of stability of each of the mineral compounds in slags have been established, it will be possible to determine the properties of any given slag by examining the nature and amounts of its mineral constituents. Earlier Investigations In 1884 and succeeding years an extensive survey of lead and copper furnace slags was made in Europe by Vogt, and a large part of the present knowledge of the subject is due to his publications.&apos; Vogt&apos;s interest in artificial fusions was directed primarily towards the explanation of problems in igneous and economic geology and his subsequent works have been confined wholly to that subject.

Jan 1, 1930

By C. J. Huffman

MAGNESIUM alloy tubing and hollow shapes are finding increasingly wider usage in practical applications today. Square and rectangular tubing and hollow shapes find [ ] greater diversification in use than standard round tubing. Typical applications are roller conveyors, ladder rungs, spools, furniture, tank car loading tubes, athletic equipment, and business machine parts. In general, the amount of tubing and hollow shapes produced represent a minor portion of the magnesium extrusion business. The magnesium alloys in which tubing and hollow shapes are being produced together with typical properties are presented in Table I. MI A alloy is a low cost alloy possessing good welding and stress corrosion characteristics together with moderate formability and corrosion resistance. It is widely used for low strength applications. AZ31 B, alloy is used for moderately stressed applications and possesses good corrosion resistance and formability with fair welding characteristics. AZ61 A alloy has slightly higher physical properties than AZ31 B alloy together with good formabil- [ ] ity and corrosion resistance but slightly poorer welding characteristics. AZ80 A, ZK60 A-F, and ZK60 A-T5 alloys are used where the maximum in physical properties is required. AZ80 A alloy possesses fair corrosion resistance but with formability and welding characteristics inferior to&apos; the other alloys. ZK60 A-F and ZK60 A-T5 alloys, while only recently offered for com¬mercial use, are finding favor due, to the higher permissible extrusion rates. These alloys possess greater toughness than AZ80 A alloy and, while of moderate formability at room temperature, are very formable at 300° to 500°F. The major portion of tubing and hollow shape production at the present time is in AZ3I B alloy. Magnesium alloy tubing is commercially available in the as-extruded condition or, in the case of ZK60 A-T5, in the as-extruded and aged

Jan 1, 1951

By AIME AIME

[The American Institute of -Mining Engineers does not assume responsibility for any statement of fact or opinion advanced in its papers or discussions.] A detailed list of the&apos; papers contained in this section is given in the Table of Contents, pages i. and ii. Comments or criticisms upon all papers given in this section whether private corrections of typographical or other errors or communications for publication as "Discussions," or independent papers on the same or a related subject, are earnestly invited. ERRATA. The following corrections and. additions to papers contained in Bi-Monthly Bulletin No. 7, January, 1906,-were received too late for incorporation in the text of said papers ; but will be introduced in their: proper places: in the volume of the Transactions: These corrections are here published in order to bring them -promptly to the notice of the Institute. Page Line Cover, title-page and at the top of pages in the preliminary section "No. 1 " should be "No. 7 ". 1. Bottom For :" Dr. P. H. Shimer" read "Dr. P. W. Shinier " 69. Fig. 3. "N" of compass-record should be ?S". A new block for this illustration has been made as shown on p. xxxviii of this Bulletin. 78. 3 from bottom. For " slope " read " stope." 89. Fig. 2, small diagram in upper left-hand corner. Omit use 50 ft. to 1" scale ". For "Thro&apos; 250 " read " Thro&apos; 200 ". Add dotted line extend¬ing from upper right-hand corner of the square

Mar 1, 1906

By Charles A. Ashburner

A very limited development has been made of the coal-fields of this Territory. This is to be accounted for by the fact that a number of the coal-fields lack railroad transportation, by the distance of other fields from the consumers (due to restricted settlements), and finally by the poorer quality of a number of coals which have been mined as compared to others which can be economically imported into the Territory. The consumption of coal in Utah during 1886, outside of that used by the railway companies, was: Tons. Utah coal,..........110,000 Wyoming coal,. .....19,000 Colorado coal,........* 4,945 Total,........... 133,945 It is estimated that there are 1100 miles of railroads in the Territory which use coal for fuel. The consumption of these roads for the year is estimated at 100,000 tons, making an aggregate consumption in the Territory of 223,945 tons. The consumption of coal in Salt Lake City duriug the year was as follows: Tone. From Grass Creek mines,.......21,000 " Pleasant Valley Company&apos;s mines,.. 12,700 " Utah Central Company&apos;s mines,.9,000 " Bock Spring mines,.6,500 " Almy mines .. ., .. .. . 6,000 " Miscellaneous sources,..5,800 Total ,.........60,000

Jan 1, 1888

By D. A. Dahlstrom

(A. C. Richardson and Charles C. Boley, presiding) W. E. BROWN*—In the operation of the cyclone, what factors have you found that will affect its results as far as efficiency goes; for example, if you have coming through the cyclone a pulp of 20 gpm, that has, say, 25 or 30 pct solids, and then from operational characteristics this pulp changes to 35 pct solids but it is still maintaining the same ratio of flow. HOW does that affect the cyclone;) D. A. DAHLSTHOM (author&apos;s reply) —It has a definite effect, as you know from Mr. Sutherland&apos;s paper,l3 in that as you increase the solid concerltration of your inlet slurry, you will naturally have an according effect on the overflow concell-

Jan 1, 1950

By Kichizo Niwa, Toshio Yokokawa, Mitsuo Shimoji, Yoshihiko Watanabe, Satoshi Kado

A LTHOUGH a systematic research on diffusion in liquid metals has not been carried out, partial studies have been developed by various workers in several systems. A few recent papers among them have shown that this line of approach is quite useful for understanding the structure of the liquid state. Furthermore, it has been found in kinetic

Jan 1, 1958

Underwood & Underwood HERBERT C. HOOVER ALBERT SAUVEUR CHAIRMAN OF WASHINGTON, D. C. CHAIRMAN OF BOSTON SECTION SECTION FREDERICK LAIST R. V. NORRIS CHAIRMAN OF MONTANA CHAIRMAN OF PENNSYLVANIA LOCAL SECTION ANTHRACITE SECTION CHAIRMEN OF SOME OF OUR LOCAL SECTIONS

Jan 6, 1919

By P. E. Senseny

INTRODUCTION Massive hydraulic fractures have been used since 1949 in the petroleum industry to enhance production rates and increase recoverable reserves. Currently, a research program, the Multi-Well Experiment, is underway to develop the understanding and technology to a1 low economic production of the large gas reserves of the low permeability, lenticular sandstone formations in the western U.S. (Atkinson, et al, 1981; Northrop and Sattler, 1983). Use of state- of-the-art hydraulic fracturing techniques is a part of this investigation. As a portion of an extensive core program in support of this experiment (Sattler, 1983), fracture toughness has been determined for 56 sandstone, shale, mudstone, or siltstone horizons from three wells in the Piceance Basin. The role of fracture toughness in hydraulic fracturing is not well understood because other factors, such as in situ stress, dominate fracture geometry and containment. Rubin (1983) concluded from analysis of his laboratory hydrofracture experiments that fracture toughness should be included in design and numerical simulation of hydraulic fractures. However, van Eekelen (1982) contends that the stress intensity at the crack front should be so much greater than the fracture toughness of the rock that toughness can have no importance. Generally, fracture toughness and other material properties, such as elastic moduli and permeability, are thought to be of secondary importance in determining fracture geometry and containment. In spite of this, there is a need to acquire a more quantitative understanding of their importance for accurate design and simulation calculations. Analysis of fracture geometry and containment data from hydraulic fracturing experiments carried out in formations where fracture toughness and other rock properties are

Jan 1, 1984

Executive HOWARD N. EAVENSON, Chairman FREDERICK M. BECKET EDGAR RICKARD ERLE V. DAVELER WILLIAM WRAITH Finance HENRY KRUMB, Chairman PAUL I). MERICA J. V. W. REYNDERS H. G. MOULTON, Consultant Admissions JOHN M. LOVEJOY, Chairman GEORGE D. BARRON DONALD M. LIDDELL ELI T. CONNER WILLIAM W. LYNCH Alternates WM. H. BASSETT, JR. L. B. LINDEMUTH W. A. SINSHEIMER

Jan 1, 1934

By Richard L. Gordon, Charles J. Johnson

Electric power demand doubles about every ten years, and because of the associated burgeoning fuel requirements, power stations absorb over half of the coal output in the United States. Throughout the 1960&apos;s, demand for coal utilized to generate electricity grew at an average annual rate of 6.5% but coal producers held back greater expansion because they expected nuclear plants to proliferate faster than they actually did. Even so, the growth rate is expected to continue at the 1960&apos;s rate until at least 1976. The continuation of the 6.5% growth rate beyond 1976, however, will require additional orders for coal-fired plants during the early 1970&apos;s. In fact, plants consuming a total of 130 million tons of coal must be ordered in the next few years. If the requisite plants materialize, total 1980 coal output for electrical power generation will be approximately 600 million tons.

Jan 1, 1971

By H. I. Smith

WHEN Spain established colonies on the North American continent, some of her land grants, in what is now the United States, reserved to the Crown deposits of gold, silver, and mercury. Later mineral rights were reserved under some of the English Crown charters involving land in the eastern part of North America, with provisions for the payment of royalties thereon to the Crown. Reservation of mineral deposits to the United States Government was instituted by an ordinance of Congress on May 20, 1785, which applied to such deposits in the Northwest Territory, then north of the Ohio River and east of the Mississippi River, and provided that there should be reserved "one third of all gold, silver, lead, and copper mines, to be sold or otherwise disposed of as Congress shall hereafter direct." Little was known then of the mineral resources of the country; the Great Lakes copper region had just come into the possession of the United States by treaty and much of the western mineral land still belonged to France and Spain. The policy of leasing mineral deposits was enacted by Congress under the act of March 3, 1807, which provided that "the President of the United States shall be, and is hereby, authorized to lease any lead mine which has been or may hereafter be discovered in the Indiana Territory, for a term not exceeding five years," and in the same year the Government reserved 345,600 acres of land in northern Illinois, valuable for lead. In 1816 Congress provided that in all cases where a tract of public land containing a lead mine or salt spring was applied for by settlers on the public domain, no permission to work the mine or spring would be granted without the approbation of the President of the United States. By the act of March 1, 1847 (9 Stat. 146), the control of mineral lands was transferred, with all records, from the War Department to the Treasury Department, and by the act of March 3, 1849 (9 Stat. 395), supervisory powers over lead and other mines of the United States were transferred to the Secretary of the Interior. Following the discovery of gold in California in 1848, President Polk advocated the leasing of mineral lands acquired from Mexico under the treaty of 1848. However, owing to the lack of communication and transportation facilities and the consequent difficulty of checking on production and operations, leasing was found impracticable. Mining was permitted to be carried on in each district under rules made by the miners themselves and patterned after the Mexican mining system. To meet the situation, Congress enacted mining laws in 1866, 1870, and 1872, which provided for possession by location and for private ownership, after discovery, by patent of essentially all mineral deposits belonging to the United States, except coal. Many other acts were passed by Congress applying to specific regions and states, reserving salt, lead, or other minerals, some of which provided for the leasing of such deposits. However, very few if any leases were issued thereunder. Not until 1901 (31 Stat. 745) were the mining laws extended to include salt, and in 1910 they were revised to specify salines and associated products. At the turn of the century, it became more and more evident that the mining laws developed for metallic minerals were not practical for the development and conservation of oil and gas, coal, potash, phosphate, or oil shale. Following withdrawals by the Secretary of the Interior as authorized by the act of June 25, 1910, the Department of the Interior recommended leasing legislation; however, it was not until February 25, 1920, that the Mineral Leasing Act was passed by Congress. This act authorized leasing all public lands potentially valuable for oil, gas, coal, phosphate, sodium, or oil shale. The Organic Act, creating the Geological Survey in 1879, imposed upon its director the duty of classifying the public lands.&apos; The early years of the Survey were devoted largely to the accumulation of fundamental data and, with only minor exceptions, land classification was not seriously undertaken until 1906. Since that year, it has been actively pursued with respect particularly to leasable minerals and water power values. On March 3, 1873 (17 Stat. 607) Congress authorized the sale of coal lands of limited acreage to individuals at $10 to $20 an acre, depending on the distance from a railroad, and in 1907 a new scale of prices was adopted by the Secretary of the Interior, based, more logically, on the quality and thickness of the coal deposits, their depth below the earth&apos;s surface, and their accessibility. At that time it was much cheaper and easier to obtain incidental title to coal rights under the homestead laws at $1.25 an acre. On March 3, 1909, the first separation act (35 Stat. 844) became a law. It authorized patents, with a reservation of the coal and mining rights involved to the United States, to persons who in good faith had entered public lands under the non-mineral land laws prior to withdrawal, classification, claim, or report that such lands were valuable for coal. It solved the problem only partially, and the practice thereupon adopted by the department of making coal withdrawals "from all forms of entry" instead of "from coal entry" expedited the more complete solution effected by later acts. By the act of June 22, 1910 (36.Stat. 583) withdrawn and classified coal lands were declared subject to entry under the homestead, desert land, and Carey acts, provided a waiver of the coal rights accompanied the application, and by the act of April 30, 1912 (37 Stat. 105) the same privilege was extended to State selections and isolated tracts. The act of August 24, 1912 (37 Stat. 496) extended the separation policy to lands withdrawn for oil and gas in Utah, and finally the act of July 17, 1914 (38 Stat. 509) extended it to all nonmineral filings on public lands theretofore or thereafter

Jan 1, 1955

By H. A. Wheeler

That lead and zinc deposits are the result of prolonged,, slow deposition is the idea of most students of ore deposits, and in many cases, where the ore-bearing solutions have been very weak or the precipitating conditions have been very feeble, the ore accumulations have undoubtedly taken a long period of time. As these two vital conditions have been subject to great variations in the different mining camps, the following example is highly interesting in showing that deposition can be very rapid under favorable conditions, geologically speaking, and also extremely recent. In fact, the writer is inclined to regard most, if not all, of the Mississippi Valley deposits of lead and zinc as probably being very young, at least not older than Tertiary, if not Quarternary, in age. The extensive Joplin lead and zinc district, in southwestern Missouri, which is about 60 years old and has numerous mines that were abandoned from 1 to 50 years ago, shows that the lead and zinc today are in an active condition of solution and redeposition, although these two metals occur in the predominant form of sulfides. The mine waters from the older and more or less abandoned portions of the district are frequently so acid, mainly from the oxidation of associated pyrite, as to necessitate the use of wooden pipes and pumps. The first boom in the Oklahoma zinc fields, which is the southwestern extension of the Joplin district, occurred when ore was accidentally struck in drilling a water well. Among the mines then opened up was the Mission mine, at Lincolnville, Ottawa County, Okla. This mine was opened in 1903 in lean "sheet ground," or a flat blanket formation of chert carrying disseminated zinc blende, or "jack," and galena. Theore-body was very free from iron pyrites and the concentrates were very high grade, the "mineral," or lead concentrates, assayed 80 to 85 per cent. lead and the jack, or sphalerite, assayed 60 to 65 per cent. zinc. The orebody was very shallow, occurring at a depth of 76 to 95 ft. (22 to 28 m.) and very wet, requiring three or four pumps to handle the water. The mine was operated until 1914, when it was closed by litigation and immediately filled with water. The second Oklahoma boom, five years ago, opened up the large, active camps of Picher, Tar River, and Century, which are located 2 to 5 mi. west of Lincolnville. They are considerably deeper, being farther down on the westwardly dipping monocline that emanates from the Ozark

Jan 1, 1920

T.P. 1958 D. H. DAVIS.*-Mr. Carris has ably pre¬sented the problems of coal preparation, particularly those brought about as the result of increased mechanical loading. Many mines are now crushing the run-of¬-mine raw coal through 12 or 15 in. immediately after it is dumped from the mine car and before it is handled by conveyors. At certain mines the removal of large slate mechanically has been solved by the installation of scalping screens consisting of bars or rails set at spacing of 12 to 15 in. on the top deck of the main raw-coal sizing screen. At the plants where these are in use, the plus 12 or I5-in. raw material contains 60 per cent or more free rock or slate, so that it is easier to pick coal than to pick rock. After the screening at 12 or 15 in. is accomplished, the oversize material is diverted to one side of the shaker, where a picker allows the refuse to pass off the shaker into a chute and guides the coal back onto the shaker. After the large rock has been removed, it is then advisable to reduce the size of rock by crushing before putting it onto a conveyor. A great saving in picking labor has been made by the use of such scalping screens, which in addition has maintained the plant capacity when handling a dirtier feed. The great increase in percentage of coal under 1/4 or 3/8 in., coupled with a greatly increased percentage of free impurities in this size, is the most serious problem that has been brought about by mechaniced loading. Many plants that formerly prepared good quality 1/4-in. to o or 3/8-in. to 0 slack by air¬cleaning are faced with installing facilities for wet-cleaning mechanical and heat-drying and water clarification. The change to wet prepa¬ration of fines usually affects the marketing problems for many coal companies. There will also be problems involving wastage of fine solids and stream pollution. Much work will be necessary for improvements in present practice. Pneumatic and electrostatic methods for cleaning fine coal should receive consider¬able attention in an attempt to avoid wet¬cleaning of fines. The preparation supervisor and the plant personnel should not be satisfied merely to run the cleaning-plant machinery and assume that the job will be done for them. Coal is a heterogeneous substance and in many instances is constantly changing. This is more true when full-seam methods are in use. Only persons trained to observe closely and make the necessary changes in plant operation will be able to solve the many problems that will be imposed on the preparation plants. The plants will require skillful and observant operating men. With full-seam mining methods, seams of roof coal will often be mined. Under the former mining systems these strata were not mined and frequently they contain a high per¬centage of bony and banded partings. The mining of this coal will greatly alter the washability and specific gravity characteristics of the feed to the plant. Often the percentage of 1.40 to 1.60 sp. gr. increased from 3.5 to 7.5 per cent, or nearly a 1.0 per cent increase in the ash content of the 1.60 sp. gr. float coal. Thus the cleaning problem is much more difficult, and it is unlikely the same ash content of cleaned coal can be produced as before without a decrease in recovery or the produc¬tion of a "middlings" product. Mr. Carris had this in mind when he said "The quality of the

Jan 1, 1946

By Allan E. Martin, Harold M. Feder, Irving Johnson

The cadmium-uranium system was studied by thermal, metallographic, X-7-ay and sampling techniques; special emphasis was placed on the establishment of the liquidus lines, The single inter metallic phase, identified as the compound UCd11 melts peritectically at 473°C to form a-umnium and melt containing 2.5 wt pct uranium. The cadmium-rich eutectic (0.07 wt pct uranium) freezes at 320.6°C. Solid solubilities in uraizium and cadmium appear to be negligible. Between 473°C and 600°C the liquidus line is retograde. NO publication relating to the cadmium-uranium phase diagram was found in the literature. The establishment of this diagram was of considerable interest to us because of a possible application of the system to the pyrometallurgical reprocessing of nuclear fuels. Analysis of liquid samples, metallographic examination, thermal analysis, and X-ray diffraction analysis were used to establish the phase diagram from about 300° to 670°C. Particular emphasis was placed on the establishment of the liquidus lines. The same system was concurrently studied in this laboratory by the galvanic cell method.&apos; Both studies benefited from a continual interchange of information. MATERIALS AND EXPERIMENTAL PROCEDURES Stick cadmium (99.95 pct Cd, American Smelting and Refining Co.) contained 140 ppm lead as the major impurity. Reactor grade uranium (99.9 pct U, National Lead Co.) was most often used in the form of 20-meshspheres. This form was particularly suitable because it does not oxidize as readily as finer powder. The liquidus lines were determined by chemical analysis of filtered samples of the saturated melts. The liquid sampling technique is described elsewhere2 alumina crucibles (Morganite Triangle RR), tantalum stirring rods, tantalum thermocouple protecthecadmiumtion tubes, Vycor or Pyrex sampling tubes, and grades 60 or 80 porous graphite filters were used. Uranium dissolves in liquid cadmium rather slowly. In order to achieve saturation of the melts it was necessary to modify the procedure of Ref. 2 by the use of more vigorous stirring and longer holding periods (at least 3 hr) at each sampling temperature. The samples were analyzed for uranium by spectro-photometry (dibenzoyl methane method) or by polar- ography. The analyses are estimated to be accurate to 2 pct. Thermal analysis was performed on alloys contained in Morganite alumina crucibles in helium atmospheres. Standard techniques were employed; heating and cooling rates were about 1°C per min. For the determination of the peritectic temperature, Cd-10 pct U charges were first held for at least 50 hr at temperatures in the range 435° to 460°C to form substantial amounts of the intermediate phase. For the determination of the effect of cadmium on the a-p transformation temperature of uranium, charges of Cd-25 pct U (-140+100 mesh uranium spheres) were first held near the transformation temperature, with stirring, to promote solution of cadmium in the solid uranium. The holding times and temperatures for these treatments were 18 hr at 680°C for the cooling run and 28 hr at 630°C for the heating run. Alloy specimens for X-ray diffraction and metallographic examination of the intermediate phase were prepared in sealed, helium-filled Vycor or Pyrex tubes. Ingots from solubility runs and thermal analysis experiments also were examined metallographically. Crystals of the intermediate phase were recovered from certain cadmium-rich alloys by selective dissolution of the matrix in 20 pct ammonium nitrate solution at room temperature. Temperatures were measured with calibrated Pt/Pt-10 pct Rh thermocouples to an estimated accuracy of 0.3°C. However, the depression of the freezing point of cadmium at the eutectic is estimated to be accurate to 0.05°C because a special calibration of the thermocouple was made in place in the equipment with pure cadmium just prior to the measurement. EXPERIMENTAL RESULTS The results of this study were used to construct the cadmium-uranium phase diagram shown in Fig. 1. This diagram is relatively simple; it is characterized by a single intermediate phase, 6 (UCd11), which decomposes peritectically, and which forms a eutectic system with cadmium. The solid solubilities in the terminal phases appear to be negligible. An unusual feature of the diagram is the retrograde slope of the liquidus line above the peritectic temperature. The Liquidus Lines. The liquidus lines above and below the peritectic temperature are based on three separate solubility experiments. The data are shown in Fig. 1 and are given in Table I. It is apparent from the figure that the solubility data obtained by the approach to saturation from higher temperatures fall on substantially the same lines as those obtained

Jan 1, 1962