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The official Institute reports for the year 1929 were distributed in pamphlet form at the Annual Meeting, February, 1930, and were later included in Section 2 of Mining and Metallurgy, June, 1930, and thus made available to the entire membership. Membership In its report the Admissions Committee set forth the changes in membership during 1929, as follows: Total membership, Jan. 1, 1928, 8582; elected and placed on rolls in 1929, including 59 reinstatements, 509; loss by resignations in 1929, 88; loss by death in 1929, 110; loss by suspension in 1929, 37; membership at end of year not including Student Associates, 8856. Distribution of membership: Honorary Members, 16; Members, 6590; Junior Members, 38; Associates, 1041; Junior Associates, 1033; Rocky Mountain, 138; total membership, Jan. 1, 1930, 8856; Student Associates, 150; total including student associates, 9006. Treasurer's Annual Report, Year of 1929 Statement of Receipts For the year ended December 31, 1929 Dues: Arrears............................................ $ 3,501.75 Current............................................ 97,257.12 New Members...................................... 5,721.50 Advance........................................... 1,970.79 $108,451.16 Initiation Fees.................................................. 7,436.OO Magazine Receipts: Advertising Gross Receipts........................... $40,610.81 Magazine Sales..................................... 3,799.84 44,410.65 Sale of Transactions Current........................... $ 2,985. 15 Sale of Special Editions Current........................ 5,147.82 Sale of Back Transactions and Special Editions........... 4,186.93 Sale of Year Book..................................... 65.50 Sale of Authors' Reprints.............................. 2,585.40 Sale of Pins and Fobs.................................. 14.73 Sale of Technical Publications.......................... 1,451.55 Sale of Bindings...................................... 3,949.13 20,376.21 Net Interest Received: On Bank Balance and Temporary Investments......... $ 2,595.04 On Lie Membership Fund........................... 3,223.43 On James Douglas Library Fund...................... 5,425.61 On General Reserve Fund............................ 2,015.58 13,259.66 Miscellaneous Receipts........................................... 335.80 Total Receipts................................................ $194,269.48

Jan 1, 1930

The official Institute reports for the year 1929 were distributed in pamphlet form at the Annual Meeting, February, 1930, and were later included in Section 2 of Mining and Metallurgy, June, 1930, and thus made available to the entire membership. Membership In its report the Admissions Committee set forth the changes in membership during 1929, as follows: Total membership, Jan. 1, 1928, 8582; elected and placed on rolls in 1929, including 59 reinstatements, 509; loss by resignations in 1929, 88; loss by death in 1929, 110; loss by suspension in 1929, 37; membership at end of year not including Student Associates, 8856. Distribution of membership: Honorary Members, 16; Members, 6590; Junior Members, 38; Associates, 1041; Junior Associates, 1033; Rocky Mountain, 138; total membership, Jan. 1, 1930, 8856; Student Associates, 150; total including student associates, 9006. Treasurer's Annual Report, Year of 1929 Statement of Receipts For the year ended December 31, 1929 Dues: Arrears............................................ $ 3,501.75 Current............................................ 97,257.12 New Members...................................... 5,721.50 Advance........................................... 1,970.79 $108,451.16 Initiation Fees.................................................. 7,436.00 Magazine Receipts: Advertising Gross Receipts........................... $40,610.81 Magazine Sales..................................... 3,799.84 44,410.65 Sale of Transactions Current........................... $ 2,985. 15 Sale of Special Editions Current........................ 5,147.82 Sale of Back Transactions and Special Editions........... 4,186.93 Sale of Year Book..................................... 65.50 Sale of Authors' Reprints.............................. 2,585.40 Sale of Pins and Fobs.................................. 14.73 Sale of Technical Publications.......................... 1,451.55 Sale of Bindings...................................... 3,949.13 20,376.21 Net Interest Received: On Bank Balance and Temporary Investments......... $ 2,595.04 On Lie Membership Fund........................... 3,223.43 On James Douglas Library Fund...................... 5,425.61 On General Reserve Fund............................ 2,015.58 13,259.66 Miscellaneous Receipts........................................... 335.80 Total Receipts................................................ $194,269.48

Jan 1, 1930

THE CHAIRMAN (G. H. CLEVENGER, Stanford University, Cal.).¬I would like to ask Mr. Pyne if he has had any experience inn the use of chromite as refractory under conditions that are highly reducing? I am reminded of an experience I once had with an electric furnace. I imagined that chromite would form a splendid lining, but it soon disappeared; hence it seems probable that, under highly reducing conditions at a high temperature, chromite is a very poor refractory. F. R. PYNE.-In copper smelting the atmosphere is generally neutral, or slightly oxidizing; we do not use highly reducing atmospheres at all, not even in the matting furnace. You can take the chromite brick and treat it as you would an iron ore, obtaining ferro-chrome very readily, from which the copper will separate. We have done this; in fact, at one time we considered installing a small electric furnace for the production of ferro-chrome. FOREST RUTHERFORD, New York, N. Y.-During the time I was general superintendent at the smelter of the Copper Queen Consolidated Mining Co., at Douglas, Ariz., a great many experiments were made on the furnaces and settlers with different kinds of brick, and I agree with Mr. Pyne's statements about chrome brick. Their power to absorb metals is very great, and as they cannot be smelted at any temperatures obtainable in a copper furnace, to get rid of the bats and extract the metal from them is quite a problem. We finally got down to using chrome brick only for lining the settlers, out of which we often got a life of upwards of 2 years, and for lining the blast-furnace bottoms, for the reason that chrome brick can be heated and wet, or wet after being heated, without going to pieces, whereas under these conditions magnesite brick will break down very rapidly. We also used a layer of chrome brick above and below an 18-in. band of magnesite brick put on the slag line of the reverberatories, in order to separate the magnesite from the silica brick, fearing that they would slag each other and let the wall drop. The idea worked, but became unnecessary on account of a change made in the method of feeding the furnaces. Chronic brick will not stand up under pressure so well as a good Grecian or Austrian magnesite brick, on account of the poorer bonding properties of the materials from which the chrome brick is made.

Jan 4, 1918

By W. Blake McCullogh

It is often written that the purpose of any mining operation is to produce efficiently, safely, and profitably, and always to search for more efficient, safer, and more profitable methods. To provide for continual improvement, an attitude that is not only reasonable but also imperative, there is an obvious need for a high standard of competence among the ranks both of supervision and of those being supervised. It naturally follows that, to achieve this standard, planned training in every level of an organization is a definite necessity. There are many factors involved in the need for training, and the scope of a program is influenced by answers to such questions as: "What is the geographic location of the project?" "What are the duties of each job?" "What is the source of the working force and supervision?" "What are the hiring standards for various jobs?" "What is the availability of trained personnel?" "What is the availability of outside training facilities?" The approach in this chapter will be to consider a need for a maximum of training, and it may be applied by the reader to whatever extent is considered necessary in each individual situation. 14.2-1. Administration. It is a basic responsibility of every supervisor at all levels to train those who work for him. However in a very extensive training program, which involves supervisors and the working force, includes both compulsory and voluntary participation, uses outside and in-plant methods, and where the increasing complexity of jobs requires more specialization, the establishment of a training department is definitely war- ranted. This will consist mainly of instructors for related classroom training and preparation of manuals, etc., and the necessary clerical help. A training staff does not relieve the various departments of their responsibility to train, but it does have facilities, experience, and contacts that are inval-

Jan 1, 1968

By R. M. Porter

The Sullivan mine of Consolidated Mining and Smelting Co. of Canada Ltd. is located one mile west of Kimberley. With its daily production of 10,000 tons, the mine is the largest in British Columbia and one of the outstanding mines of the world. The Sullivan orebody dips from nearly horizontal to 45". The ore zone is a bedded replacement de- posit in argillite with a width varying from a few inches up to 300 ft. The main sulfide minerals are pyrrhotite, pyrite, galena, and sphalerite. The chief metals produced are lead and zinc, with less important qualities of iron, silver, tin, antimony, bismuth, cadmium, indium and sulfur.

Jan 12, 1963

By P. A. Young

The historical background of on-strand cooling is given, together with a resume of recent practical developments. Laboratory test procedures are then considered in detail, for both productivity and quality parameters, with particular reference to the design of the Ravenscraig No 3 machine (Scotland). A heat transfer model is presented for a porous sinter with propagating cracks. The influence of cooling/sintering area ratio, sinter strength, granulometry, return fines, coke consumption and FeO levels are examined in relation to economics. A detailed comparison of capital and running costs for two different strands, designed for identical duties, but with off or on-strand cooling, is then given.

Jan 1, 1977

By R. D. Carnahan, J. E. White

A study of dispersion strengthening in TD-Nickel (nickel plus 2 vol pct Tho2) was conducted employing microstrain techniques at ambient room temperature. It was found that optimum strength was due primarily to the incorporation of stored energy developed by a variety of thermal-mechanical treatments. The relatively low strength of the recrys-tallized condition implies that the dispersed particles themselves offer only token resistance to deformation. The development of resistance to large-scale recovery or recrystallization at temperatures near the melting point requires a more extensive sequence of strain-anneal cycles than does the development of optimum strength. A micro-Bauschinger effect was observed which appears to be related to the lattice resistance to the movement of free dislocations. The effect was nearly identical to that in pure nickel indicating that the presence of the dispersed phase and considerably increased dislocation density (stored energy) only alters the number or effectiveness of barriers. THE early stages of deformation of engineering materials can be conveniently studied by utilizing strain-gage techniques which permit resolution of strains less than 5 X 10-7 in. per in. for testing in four-point bending (Carnahan and white1). The present investigation, part of a continuing study on the very early stages of deformation, was designed to reveal the true role of a dispersed phase in promoting high strength in a commercially available dispersion-strengthened alloy. Although this technique has been used for some time to study microdeformation in pure metals and alloys, it has just recently received attention as a means of investigating dispersion strengthening. Studying the very early stages of deformation in alloys which depend upon a finely dispersed inert phase for strength may prove to be a very important method for a better understanding of these materials. It is essential to obtain considerable clarification of actual dislocation movement and the kinds of deformation barriers which exist before optimum properties can be designed into this type of material with any degree of confidence. Considerable research on a variety of dispersion-strengthened materials has resulted in two different schools of thought regarding the strengthening mechanism. One faction2-4 favors the idea that the particles themselves resist the motion of dislocations. The criterion for yielding is the fracture of the dispersed second-phase particles due to an array of piled-up dislocations. Other invesfigators5-a have shown that particles are effective primarily by allowing a greater buildup of stored energy or dislocation density through thermal-mechanical treatments in the composite than the pure matrix material. The particles themselves, then, are not exclusive obstacles, but the complex network of particles, dislocation tangles, subboundaries, and grain boundaries are strength determining. The development of such a complex dislocation network in SAP has been studied recently in some detail by Goodrich and Ansell. The ability of dispersion-strengthened alloys to resist softening or recrystallization is also of considerable importance; however, the criteria for maximum stability may not necessarily be those for maximum strength. In this study, in addition to the evaluation of the microstrain properties of TD-Nickel, it is felt that considerable clarification of the true dependence of strength and stability on the dispersed phase is shown. I) MATERIAL AND PROCEDURE TD-Nickel is a dispersion-strengthened alloy developed by the E. I. DuPont de Nemours Co., which contains 2 vol pct thoria (Tho2) in a pure-nickel matrix. The average ThO2 particle size is approximately 0.1 p and the interparticle spacing is less than 1 u. The material was supplied by DuPont in two conditions: hot-extruded bar stock, and stress-relieved cold-rolled sheet 0.025 in. in thickness. The bar was extruded at 2200°F from a cold-pressed and sintered billet. The sheet stock was prepared from the extruded material by a process involving ten or more 50-pct cold reductions by rolling with intermediate anneals at 1800° to 2000°F. Test specimens used in this study were prepared in the form of rectangular parallelepipeds measuring 0.375 by 1.375 in. in thicknesses ranging from 0.025 to 0.040 in. Samples prepared from sheet and extruded stock were mechanically polished before heat treatment and were handled with extreme

Jan 1, 1964

By AIME AIME

THE following compilation of State bureaus and officials that deal with mineral resources is compiled in part from a new "Check List of State Agencies and Officials Concerned with the Management of Natural Re- sources," compiled for the National Resources Committee, Washington, D. C., by Clifford J. Hynning. Alabama-Geological Survey of Alabama, University. Walter B. Jones, State Geologist. Chief Mine Inspector: W. B. Hill- house, 614 Lincoln Life Bldg., Birmingham.

Jan 1, 1939

Jan 1, 1907

By V. R. Garfias, R. V. Whetsel, J. W. Ristori

Preliminary estimates indicate that world consumption of petroleum and related fuels in 1938 will be close to 1,908,000,000 bbl., or approximately 7,000,000 bbl. less than in 1937. This total does not include military consumption in foreign countries, which for obvious reasons is not made public. Foreign military consumption in any one year, however, is approximately represented by the difference between the total production of petroleum and related fuels and the "partial total" consumption above noted, after adding any decrease, or subtracting any increase in stocks in the United States. Fig. 1 illustrates this "difference" and shows that in 1937 and 1938, owing to the wars in China and Spain and the possibility of armed conflict in Central Europe, foreign military consumption—and possibly additions to foreign stocks—increased nearly 70,000,000 bbl. in 1937 over 1936 and remained at this high rate throughout 1938. No official information on foreign oil stocks is available to the writers. Table 1, recently published, purports to give the oil in storage in some of the European countries, but it is not known whether the figures include oil stocks for military purposes. It should be noted that with the annexation by Germany of Austria and part of Czechoslovakia the consumption of the country has increased to 53,000,000 bbl., which is about 36,000,000 short of the German produc-

Jan 1, 1939

By J. W. Ristori, R. V. Whetsel, V. R. Garfias

Preliminary estimates indicate that world consumption of petroleum and related fuels in 1938 will be close to 1,908,000,000 bbl., or approximately 7,000,000 bbl. less than in 1937. This total does not include military consumption in foreign countries, which for obvious reasons is not made public. Foreign military consumption in any one year, however, is approximately represented by the difference between the total production of petroleum and related fuels and the "partial total" consumption above noted, after adding any decrease, or subtracting any increase in stocks in the United States. Fig. 1 illustrates this "difference" and shows that in 1937 and 1938, owing to the wars in China and Spain and the possibility of armed conflict in Central Europe, foreign military consumption—and possibly additions to foreign stocks—increased nearly 70,000,000 bbl. in 1937 over 1936 and remained at this high rate throughout 1938. No official information on foreign oil stocks is available to the writers. Table 1, recently published, purports to give the oil in storage in some of the European countries, but it is not known whether the figures include oil stocks for military purposes. It should be noted that with the annexation by Germany of Austria and part of Czechoslovakia the consumption of the country has increased to 53,000,000 bbl., which is about 36,000,000 short of the German produc-

Jan 1, 1939

By Nathaniel Arbiter

In attempting to assess the contributions of Antoine Gaudin to the profession which he illuminated for almost a half-century, we will need to examine a very broad canvas. He was active in three significant areas: as a teacher; in research, both through his own endeavors and those of his students; and as a consultant to the mining industry and to the Government. Beyond these specific contributions, there was the major personal influence he had on scores of students, friends, and colleagues in the profession. If a single measure of the man's contribution is to be found, it will be the extent and direction in which he influenced the practice of his profession. To find this we should examine the state of miner- al processing when he began his activities in the 19201s, the progress which has taken place over the past half-century, and the part his activities played in this advance. However, there is a provocative and broader examination which I have chosen to make instead. This is to examine the past century in mineral processing through the lives of three men who, by common agreement, stand on the heights, both in teaching and in their contributions to industry: Robert H. Richards, Arthur F. Taggart, and the man whose memory we honor this evening, Antoine M. Gaudin. Their careers, by coincidence, cover just a century. This is also AIME's first century, and the first century of mineral industry education in the United States. In fact, mineral processing itself on any significant scale in the country encompasses only a century and a quarter. BEGINNINGS OF PRACTICE IN THE U.S. Before the 1840’s, U.S. mining, except for coal and iron ore, was on a small scale and was confined to the eastern states, with processing practically nonexistent. The 1840's saw the beginning of Michigan native copper production, including ore dressing; the 1850’s, iron ore production in Minnesota; and the 1860’s, lead production and processing in Missouri. But the most explosive event was the California gold rush after 1848, which not only brought tens-of-thousands of fortune hunters to the West, but also catalyzed broad mining activities and processing within the following decades. This was not only in California but, after the first fever of the gold rush subsided there,

Jan 1, 1976

By F. A. J. Fitzgerald

In any kind of furnace the question of preventing the loss of heat is important, for no matter how the heat is obtained it costs something; and consequently, other things equal, that furnace is most desirable which uses the greatest percentage of the total heat generated for the particular object in view. In the furnace which uses electricity for the generation of heat the importance of preventing losses of heat is very much greater than in any other. To generate 1,000 kg-cal. requires an expenditure of 1.16 kw-hr., and consequently the cost per calorie is always expensive when electricity is used for heating. In heating any material in a furnace a general rule is that the generation of heat should be as rapid as possible. In any given furnace the heat-losses may be expressed as so many watts, and, therefore, the longer it takes to heat the furnace-charge the greater the losses will be. Suppose that a furnace contains a charge to be heated to 1,500°C. and that the average loss of heat is at the rate of 100 kw., then if the process of heating the charge takes 1 hr. the losses will amount to 100 kw-hr.; but if by using a more rapid generation of energy the charge can be heated in 30 min. the losses will amount to 50 kv-hr. An example from experiments on a certain process may be given to illustrate this point. The problem was simply to heat a furnace-charge to a certain temperature, and experiments were made to determine the effect of increasing the rate of generation of energy and comparing the kilowatt-hours required to heat a given charge. Here are typical results : Rate of Generation Energy Per Kg. of Energy. of product 88 kw. 1.7 kw-hr. 93 kw. 1.6 kw-hr.

Jan 1, 1913

By Edward C. J. Urban

The nature of certain pernicious dusts commonly encountered in the removal of iron ore from the underground mines of the Lake Superior district is recognized, and appropriate measures for the protection of individuals subjected to these dusts have been applied in most mines for more than 10 years. Undoubtedly the principal concern has been demanded by dusts that contain as a constituent silicon dioxide in its free or uncombined state, the mineral we all know as quartz or chert. Investigators1 agree that among the factors that determine injurious exposure are: the composition of the dust, the concentration suspended at the breathing level and the duration of the exposure. We have on hand data that describe the experience of several underground iron-ore mines in the Upper Peninsula of Michigan and Wisconsin in regard to these factors, which in a large measure also reflect the general experience of the other mines of the area. We believe that a discussion of these data will indicate the effectiveness of the dust-control methods that have been considered good practice and that have been employed over a long period of time. A silicosis-prevention program was ini- tiated by the iron mines of the Upper Peninsula in 1934 and records of mine dustiness are available from that date to the present time. For dust conditions previous to 1934 the results of observations conducted in other industries can be utilized together with local information pertaining to the development and initial application of rock-drilling equipment. Development of Rock DriI,I.s Thc earliest percussion rock drill that later had any industrial use was patented in this country in 1851.2 This machine was later modified and improved in many respects but its Piston-Type design remained standard for drilling equipment in most mines for the next 63 years.3 The piston drill was operated either by air or by steam. It employed a solid drill steel, fastened directly to the reciprocating piston. The drilling was done dry except in holes directed at an angle below the horizontal. For these water was manually injected into the hole and the pumping action of the rod expelled the sludge. The dry cuttings from drillings inclined above the horizontal fell from the hole by their own weight. A development of major importance from the standpoint of dust generation and control occurred with the invention by J. G. Leyner of a hammer-type rock drill that embodied the essential feature of a drill steel with a hollow core. His patent was secured in 1897. The machine was a radical departure in drilling method. The steel was held loosely in a chuck while

Jan 1, 1949

By Sydney H. Ball

MINERALS used primarily for personal adornment and decorative purposes are called precious stones. To be so prized, the stones must possess beauty of color, must not be too common, and must be hard enough to withstand ordinary wear. If transparent, they must have brilliancy and fire. Almost one hundred minerals have been used as precious stones, the noble gems being the diamond, emerald, ruby, and sapphire; pearls are frequently included by courtesy. These gem stones, however, are sometimes equaled in beauty by fine opals, aquamarines, ourmalines, spinels, chrysoberyls (both cat's-eye and alexandrite), and spodumenes (hiddenite and kunzite). The Greeks, Romans, and medieval Europeans grouped together gem stones according to color and degree of transparency, and only as the niceties of mineralogy began to be known, about a century ago, was it realized how many different minerals have the beauty required of gem stones. Pliny, for example, did not distinguish between rubies and the red varieties of spinel and garnet, although he conjectured that the beryl and emerald were one mineral. GENERAL SURVEY Early man treasured bright colored berries, attractive shells, white teeth of wild animals and brightly colored pebbles, and used them as personal ornaments. In the eastern hemisphere, the earliest stones used were members of the quartz family (100,000 to 75,000 B.C.); then obsidian and amber (50,000 to 25,000 B.C.); the jade minerals, fluorspar and jet (22,000 to 7000 B.C.); turquoise (7000 to 3400 B.C.); lapis lazuli and garnet (prior to 3500 B.C.) ; emerald (2000 to 1800 B.C.) ; sapphire, ruby and diamond (800 to 500 B.C.). Indeed, gem mining is the oldest form of mining, and before any metals were known primitive man recognized about 18 gems and decorative stones. At first he sought them in stream gravels and residual deposits but by 3400 B.C. the turquoise mines of the Sinai Peninsula were operated. This was the world's first important hard-rock mining enterprise. The Afghanistan lapis lazuli mines may

Jan 1, 1949

By Henry Fay

LAWRENCE ADDICKS, New York, N. Y., (communication to the Secretary *).-There are two points regarding gun erosion on which I want to say a few words: The first is about the analogy to hardening of wire by drawing and the second the possible role played by thermal conductivity of the metal. The ductile metals do not necessarily become brittle when cold-worked as it is possible to draw copper from 3. in. in diameter soft rod down to the finest hair wire without annealing. This results, as stated in the paper, informing a hardened core with a very hard skin. The electrical conductivity is depressed some 3 per cent. and the tensile strength nearly tripled. A soft copper wire 0.08 in. in diameter and 6 in. long may be twisted 150 or more turns before the wire will snap under torsion. A hard-drawn wire will break after perhaps a dozen twists, the skin breaking down at one spot. Just wiping the wire with a cloth clamp with dilute nitric acid has a remarkable effect in increasing the number of twists without appreciably lowering the tensile strength, showing the skin to be very thin. On the other hand, pickling the rod, from which the wire is to be drawn, in dilute nitric acid also greatly increases the number of twists which can be applied to the resulting wire. This indicates that the copper oxide scale produced when the wire bar is rolled hot is more or less rolled into the rod and may have much to do with the skin effect. We also know that if the conditions of drawing are not correct, the heat of deformation in the die may produce quite an annealing effect. The application of this analogy to what occurs in a gun to produce the effects noted offers some difficulty. The second point is that as the temperature of the surface of the gun bore has undoubtedly a great deal to do with the amount of erosion, one natural remedy would be to conduct the heat away fast enough to keep this temperature within desired limits. This brings up the question of the thermal conductivity of the metal of which the gun is made. We know that the conductivity of pure metals is greatly altered by alloying and that the alloy is usually, though not always, lower in conductivity than the metal before alloying. This is interesting when it is considered that the high-nickel and manganese-steel alloys show greater erosion as stated. Would it not be instructive to study the question from the point of view of heat conducted away from the eroded surface?

Jan 3, 1917

By Orrin Peterson

THE decision of the Supreme Court of the United States not to review the findings of the lower courts closes an interesting chapter in the mining litigation that has arisen as a result of the extralateral feature of the mining law. The time seems opportune to record some of the important geological features, and also some of the legal features, of the controversy, in the hope that these will be permanently accessible to members of the mining profession. After many rumors of litigation, the Utah Consolidated Mining Co. sued its neighbor for the ore that had been, it was alleged, wrongfully extracted from its so-called Yampa limestone lode. This ore lay beneath Utah-Apex surface and was claimed by virtue of the extralateral rights conferred on the Utah Consolidated Co. through the ownership of certain specific mining claims, one of the principal claims being the Yampa. Previous to bringing suit, the Utah Consolidated Co. had strengthened its position by purchasing the Old Yampa mine and by making an agreement with the Utah Metal & Tunnel Co., which gave it clearer title to the outcrop of the Highland Boy limestone. Access to the workings of the Utah-Apex Co. was secured and reciprocal privileges gave Utah-Apex representatives the right to enter the properties of the Utah Consolidated Co. This resulted in the Utah-Apex immediately bringing countersuit for ore alleged to have been wrongfully extracted from under its surface in the Leadville country, see Fig. 4. Six cases came up for consideration: five related to the original suit and the countersuit, and one related to the Dana extralateral claims of the Utah-Apex Co.

Jan 6, 1924

By R. A. Foos

During the radium boom in the early part of the twentieth century, the basic chemistry of uranium was fairly well defined. Uranium production has progressed from the status of a radium by-product to a very important industry. With the ever increasing need for more efficient and cheaper methods of processing uranium ores, new techniques are being developed. Since uranium and vanadium often occur together in nature, the latter element will also be considered. As production rates, costs, and certain aspects of uranium chemistry are still classified by the Atomic Energy Commission, these will not be discussed. Domestic uranium deposits, in general, are composed of the minerals carnotite, which contains hexavalent uranium, and to a lesser extent, pitchblende and uraninite, which contain tetravalent uranium. Carnotite also usually contains vanadium. The uranium and vanadium contents of these ores vary considerably. The ores currently processed on the Colorado Plateau assay from 0.2 to 0.4 pct U and from trace amounts to 5.0 pct V. On the other hand, the phosphate rock deposits of the southeastern U. S., from which uranium is also recovered, contain only about 0.01 to 0.02 pct; processing of the

Sep 1, 1956

By W. M. McKewan, R. G. Olsson

In order to improve the understanding of the iron oxide reduction mechanism, the rate of equal molar diffusion of hydrogen and water vapor was measured through disks of porous iron and alumina. The measuretneizts were made at atmospheric pressure at 800°, 900- , and 1000°C. It is shown tint the reduction of dense hematite pellets with hydrogen at these temperatures and at atmospheric pressure is to a great extent limited by gaseous diffusion between the bulk-gas phase and the iron-wustile interface. THE investigation of the reduction of iron oxides with hydrogen has been the subject of numerous papers. Although the effects of temperature, pressure, and gas composition on the rate of iron oxide reduction have been studied, the actual mechanism of the reduction process has not been definitely determined. As a means of improving the understanding of the mechanism, the rate of equal molar counterdiffusion of hydrogen and water vapor was measured through porous iron and porous alumina disks at reduction temperatures. The alumina was used as a basis of compari-son because its pore structure is homogeneous and independent of temperature. The porous iron was prepared by the reduction of dense hematite disks with hydrogen at the temperature of the subsequent diffusion experiment. The hematite disks were made from pellets that were identical to those used by McKewan1,2 in his study of iron oxide reduction with hydrogen. In these investigations the weight loss and rate of movement of the various interfaces were measured as a function of the reduction temperature and gas composition. With these reduction data and the presently reported diffusion data it is possible to determine the importance of H2-H2O transport between the bulk-gas phase and the Fe/FeO interface to the reduction of dense hematite. APPARATUS AND PROCEDURE A porous iron or alumina sample was held in the base plate of a sealed canister containing porous granular wustite, as illustrated schematically in Fig. 1. The canister was suspended from an automatic recording balance in a vertical tube furnace through which flowed hydrogen and water-vapor mixtures of known composition at atmospheric pressure (0.96 atm). Hydrogen from the gas stream diffused through the porous sample, reducing the wustite in the interior of the canister. The water vapor that was formed diffused back to the gas stream. The rate of diffusion was determined from the recorded weightloss data. The furnace, automatic balance, and gas-metering equipment have been described previously.2 The main body of the canister and the tubing extension were made of stainless steel while the base plate was made of high-purity iron. The main body of the canister was % in. in diam. It held approximately 6 g of porous granular wustite that was prepared by reducing 0.1- to 0.2-cm-diam specular hematite particles at 900°C with an H2-H2O mixture of a composition near the iron-wustite equilibrium value. The upper end of the 1/8-in.-diam tubing extension was sealed with a segment of plastic tubing and a tubing clamp. The temperature at the top of the furnace was sufficiently high so that no water vapor condensed inside the extension. In the experiments with porous iron, iron oxide samples were prepared from reagent-grade hematite that was pressed and sintered in a manner previously described.' The resulting pellets had a density of 5.15 ± 0.05 g per cu cm. Each pellet was centerless-ground

Jan 1, 1967

By D. P. Pope, T. Vreeland

Observations of dislocations in zinc using Berg-Barrett X-ray micrography confirm the validity of a dislocation etch for (1010) surfaces. A technique for measurement of the depth in which dislocations can be imaged in X-ray micrographs is given. This depth on (0001) surfaces of zinc was found to be 2.5 µ using a (1013) reflection and CoKa radiation. BUCHANAN and Reed-Hill (B & RH) have recently questioned the ability of a dislocation etch to reveal all of the basal dislocations which intersect (1010) surfaces in annealed zinc crystals.' This etch was developed by Brandt, Adams, and Vreeland who conducted a number of different experiments to check its ability to reveal dislocations.2,3 B & RH prepared (0001) foil specimens for transmission electron microscopy from annealed crystals and observed dislocation densities of about l08 cm per cu cm in the foils, while the etch indicated densities of the order of l04 cm per cu cm in their annealed crystals. As this etch has been used in a number of studies of dislocations in zinc, it is of considerable importance to reassess its validity in the light of the B & RH results. The X-ray work reported here was undertaken to check the ability of the etch to reveal dislocation intersections on (1070) surfaces of zinc. The X-ray technique was chosen for this check because it could be applied to the as-grown crystals with a relatively small amount of specimen preparation. We believe that the possibility of accidental deformation in preparation of the bulk specimens is considerably less than that for thin foil specimens suitable for transmission electron microscopy. Unfortunately, basal dislocations are not visible on Berg-Barrett topo-graphs of (1010) surfaces, which are the surfaces on which the etch is most effective. Therefore, a one-to-one correspondence between the etch and X-ray observations could not be made. Basal dislocations near (0001) surfaces have been observed by Schultz and Armstrong4 using the Berg-Barrett technique, but they did not report the as-grown dislocation density observed in their crystals. We have applied the X-ray technique in this study to surfaces oriented from 1 to 2 deg of the (0001) to determine the basal dislocation density, and have compared this density with that observed using the etch on a (1070) plane of the same crystal. The X-ray observations permit determination of the depth in which basal dislocations can be observed under the diffracting conditions used. SPECIMEN PREPARATION High purity zinc crystals are very soft, so a good deal of care must be exercised in the preparation of observation surfaces. As-grown crystals approximately 2.5 cm in diam and 20 cm long were acid cut into 1.25 cm cubes. A thin slab was cleaved from an (0001) surface to produce an accurately oriented reference surface on the specimen. Some of the cubes were examined in the as-machined condition while some were annealed in argon at 410°C for 2 hr. Heating and cooling rates were less than 2°C per min. Some of the specimens were scratched on a (0001) surface with a razor blade to produce fresh dislocations. Approximately 2 mm of material was acid lapped from one face of a cube to produce a surface oriented between 1 and 2 deg from the basal plane and parallel to the [1210] direction. A (1070) surface was also acid lapped. The lap used a 1 to 3 pct solution of HN03 in water to saturate a soft cloth which was backed by a stainless steel plate. The cloth was moved over the crystal surface at a rate of 20 cm per sec while a normal force of about 4 g was maintained between the cloth and the specimen. As-lapped surfaces were examined as were surfaces which were chemically and electrolytically polished after lapping. The small angle between a lapped surface and the (0001) plane was measured to 0.1 deg using a Unitron microgoniometer microscope (the cleaved surface was used as a reference in this measurement). The microscope was modified so that the intensity of reflected light could be continuously monitored on a meter. This modification produced nearly a ten-fold increase in the reproduceability of orientation readings. OBSERVATIONS The Unitron Microgoniometer observations indicated that the lapped surfaces had a terraced structure with the terraces quite rounded and spaced about 0.1 mm in the [1010] direction. The maximum change in slope between terraces was 0.25 deg, indicating a terrace height of about 0.1 µ. A Unitron measurement of the average angle between (0001) and a lapped surface was checked by micrometer measurement of the specimen and found to agree within 0.1 deg. The Berg-Barrett micrographs using (1013) reflections and CoKa radiation5 revealed subboundaries, short dislocation segments, spirals, and loops near the surfaces which were oriented from 1 to 2 deg of the (0001). Micrographs of surfaces prepared by lapping appeared very similar to those of the chemically and electrolytically polished surfaces. The loops and spirals were not extinct in (1013) or (0002) reflections, indicating that they have a nonbasal Burgers vector. Extinctions of the short, straight dislocations indicated that they belonged to an (0001)(1210) system. Fig. 1 is an example of a micrograph which shows a subboundary, and dislocation segments which are pre-

Jan 1, 1970