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Do not write until you have something to say. Think first; then write. In order to be understood, you must know what you wish to say. Clear writing is the consequence of clear thinking. Therefore consider your subject well before you begin to write; ruminate on it; marshal the salient facts in your mind; saturate yourself with the ideas you wish to express and with cognate ideas; then express yourself deliberately. If you are bubbling over with your subject the words will come, but you might as well expect to sail without a breeze as hope to give life to words without the living thought. Here I may advert to the fact that among the uneducated it is a common expectation to acquire the knack of writing without taking the trouble to study the art of literature. I overheard a woman in a suburban train remark to her neighbor: "I'd like to be able to write well without stopping to think about it". She was one of many that would like to do a thing well without the trouble of thinking; but it cannot be done in respect of anything to which thought is essential. The possession of a good voice does not justify a person in expecting to sing successfully to a large audience; before singing in public one has to master the technique of singing; one has to learn first how to breathe properly, how to enunciate, and many other things. The successful singer is an artist, not a megaphone. Most of us would regard a man or a woman without any training in the art of singing as a fool or an impostor if he or she were to give a public concert, yet we do not recognize the equal foolishness and imposture of persons that write books before they have studied the technique of writing. That is why so many books are unreadable, and why many books by clever men are difficult to read. They start to write books before

Jan 1, 1931

By G. D. Rieck, G. H. G. Vaessen, D. L. Vogel

Both doped and undoped tungsten single crystals exhibit hardness anisotropy with respect to the direction of testing in each of the crystallographic phes investigated. The hardness anisotropy of undoped single-crystal tungsten is rather pronounced in (001) and (110) planes but very minor in (111) planes. The anisotropy in (122) planes of the doped and drawn tungsten after recrystallization is in accordance with a previously published concept of a stringlike distribution of the doping material in the metal. ANISOTROPY in mechanical properties of single-crystal tungsten was investigated by Rose et al., Garlick and Probst,2 and Beardmore and Hull. 3 Although data on the Vickers microhardness of tungsten have been published (see, e.g., Boosz 4 and the references cited by him), no data on the microhardness anisotropy are available. We report, therefore, some of our own results on the microhardness and its anisotropy. The microhardness has been determined of the following samples. A) Polycrystalline tungsten samples taken from: 1) powder metallurgical tungsten "normally" doped with potassium-silicon-aluminum oxides (final contents inppm: K, 100; Si, 100; Al, 20; Cr, 20; Fe, 50; Mo, 400; Ni, 10) and in the form of: a) a 10-mm-diam swaged ingot annealed at 1600°C, the grain sizes varying between 15 and 250 p; b) a sheet rolled at about 800°C and recrystallized at 2000°C7 the grain sizes varying between 15 and 150 p; c) a 2-mm-diam swaged rod, as-worked, with elongated grains (average diameter of about 25 , lengths up to 1 mm); 2) undoped electron-beam-melted tungsten with very large grains (contaminations in ppm: K < 10; Fe < 20; Cr < 10; Cu < 0.1; Ni not detectable; inter-stitial~ not determined). B) Single-crystal samples taken from: 1) pure tungsten grown on a Pintsch wire by the van Arkel procedure (main contaminations inppm: Mo, 100; Si < 10; Cu and Fe, 2; A1 < 2; interstitials not determined); 2) zone-melted undoped tungsten (analysis as under A2); 3) large crystals in secondary recrystallized tungsten

Jan 1, 1969

By C. A. Heberlein

C. A. HEBERLEIN,* New York, N. Y.-The results stated by Rey and Brevers are so startling that they are of great interest, as the concentration of a low percentage of cinnabar by differential flotation yields a high-grade concentrate in the presence of either arsenical or iron pyrite. The authors say: "Cyanide can thus be used to depress arsenopyrite and make a good cinnabar-arsenopyrite separation. A cinnabarpyrite separation could probably be effected in the same way." Corrosive sublimate at the present price of mercury would be a very expensive reagent but the expense would be justifiable if a high rate of concentration could be obtained with a high extraction. On my request, special tests were made in the Punitaqui mill in Chile along the line suggested by the authors, without any improvement of either grade or extraction. As the recovery of the cinnabar in a complex sulphide of chalcopyrite and pyrite gave unsatisfactory results, I had tests made at the testing laboratory of the American Cyanamid Co. at Stamford, Conn. As these tests turned out to be highly satisfactory, not only at Stamford but later at the mine, they are presented here. [AMERICAN CYANAMID TEST FEED PER CENT Si02 66.54 A12032.08 CaO0.70 MgO 0.00 Alkalis1.78 Fe15.63 Cu0.44 S9.42 Hg0.45 OZ. PER TON Ag0.95 Au0.151 Screen Analysis of Tailings, Per Cent Plus650.0 Plus 1001.32 Plus 15020.75 Plus 20019.85 Minus 20058.08] The pulp had a density of 22 and a pH of 7.8. Total time of conditioning was one minute. The reagent added was Texas fuel oil, 0.116lb. Of 33.7 Bé. gravity containing 0.9 per cent sulphur. Frother, 0.062 lb. of No. 5 pine oil. Rate of concentration of mercury was 25.7: 1 [ ]

Jan 1, 1941

By Raymond M. Howe

Additional data have been secured on the disintegration of furnace linings and the spalling of stove brick. The first article on the disintegration of furnace linings appears to have been written by John Pattinson in 1876.l The furnace involved was 85 ft. (25.0 m.) higher and 27 ft. (8.2 m.) in diameter at the boshes; after being in blast five years, the top brick became contaminated with carbon and disintegrated. An examination of the lining showed that the discolored, disintegrated brick were in a zone found from 35 to 67 ft. (10.6 to 20.4 m.) above the hearth; immediately below, in a zone extending from 22 to 40 ft. (6.7 to 12.1 m.) above the hearth, the brick were hard and porcelain-like in appearance. Analyses of samples taken from the different sections are given in Table I. The water-soluble portion found in the sample taken 39 ft. (11.8 m.) above the hearth had a composition approximately as follows: silica, 0.50 per cent.; lime, 0.04 per cent.; potash, 0.78 per cent.; soda, 0.20 per cent.; potassium chloride, 6.19 per cent.; moisture, 1.03 per cent.; total, 8.74 per cent. The carbon Table 1.—-Analyses of Samples Taken from Diferent Sections of Furnace . I ii In Iv v Section 67 Section 45 Seotion 39 Section of Original ft Above ft above ft above vitrified Lining Hearth Hearth Hearth Portion Per Cent. per Cent per Cent per cent. per Cent Silica........................... 55.70 55.60 55.67 47.60 37.07, Alumina........................ 35.50 35.40 30.00 26.47 23.18 Ferric oxide..................... 3.00 1.32 0.96 Lime........................... 0.23 0.06 0.17 Magnesia....................... 1.22 0.95 0.86 0.00 Potash......................... 2.60 2.10 5.30 7.54 21.59 Soda.........,.................. 0.45 0.42 1.67 0-76 6.28 Ca1bon ......................... 2.05 3.24 5.97 Carbon dioxide.................................. 2.. 17 Water...................................... 7.70 Water-soluble........................... 8.74

Jan 1, 1920

South Dakota State School of Mines, Rapid City, S. D. C C O&apos;Harris,-President. A number of technical bulletins have been issued at the South Dakota State School of Mines but, unfortunately, most of them are out of print and as this directory is concerned only with available publications, the following are all that are now to be had Bulletin 11, A bibliography of the geology and mining interests of the Black Hills region (1917), no charge; 14, The geology, mineralogy, and scenic features of Custer State Park (1926), 40 cents plus postage on 1 lb ; 15, The Tertiary mineralization of the northern Black Hills (1927), charge, postage on 1 1b.; 16, The mineral wealth of the Black Hills t418 pages) (1929), 80 cents plus postage on 3 lb

Jan 1, 1933

By F. D. Rosi

IT was recently shown1 that slip bands can be observed in bent germanium crystals after deformation, by means of etch pits along the slip traces. It is the purpose of this note to show how chemical etch pits can also be usedto examine the appear- ance of slip bands in silicon, as well as other deformation markings. A 30 ohm-cm, p-type single crystal bar, 2x1/4x1/8 in., was plastically bent at approximately 1200°C in a vacuum of 1x10-5 mm Hg. The axis of the crystal was coincident with a <III> direction, and the surface normal to the axis of bending was within 4" of a (110) plane. Prior to the deformation, the (110) surface was mechanically polished with

Jan 1, 1958

By H. I. Smith

THE technical and safety press have devoted much space in support of or in opposition to the use of booster and auxiliary fans in coal mines. The Mine Safety Board of the U. S. Bureau of Mines has given the matter consideration, and the Mine Ventilation Committee of the A. I. M. E. is now seeking a discussion of the merits and demerits of such fans to guide it in formulating recommendations. In this paper, I will set up some principles on which I believe most engineers will agree and from which we may work toward a decision, though as to what that decision shall be there may be a difference in opinion. Before stating the points on which I believe. there is accord, I will distinguish between booster and auxiliary fans.

Jan 1, 1927

By A. Rakshit, W. E. Kolb, Y. C. Kim

An IBM/XT microcomputer with 10 MB hard disk storage, together with automatic sensing capability of truck movements at several key locations in the pit, formed the core of this automatic truck dispatching system. System software is written primarily in MICROSOFT FORTRAN with supporting subroutines in MACRO assembly language. The software is designed to automatically monitor truck movement throughout the pit, to make heuristic assignments based on expected shovel availability and truck travel times, and to record production statistics. It is currently dimensioned to handle 50 trucks, 10 shovels, 10 dump sites, and three material types. Due to the lack of funds to purchase the necessary communications hardware, the work related to the automatic sensing of truck movements has not been performed to date. Otherwise, the system is fully operational on a realtime mode.

Jan 1, 1986

By D. Y. Geng, S. S. Peng

Surface subsidence of two longwall panels, one with a private residence and the other with an arch bridge, was monitored over a period of 1 to 1&apos; ½ years. Surface subsidence data were analyzed in terms of zone of advance influence and delay angle of maximum subsidence velocity. The variational characteristics of both features coincide with the periodic weighting at the advancing longwall face. Surface heaving in the subsidence process can also be attributed to periodic weighting. It was found that residential damages occurred when subsidence velocity exceeded 4.5 mm/day (0.15 ft/day). The effects of locating structures on the panel center and near the gob edges are illustrated. The effect of mining on ground water was also discussed. Finally, methods of reducing structural damages are recommended.

Jan 1, 1984

By J. B. Goddard

In situ leaching of uranium by aqueous ammonium carbonate containing oxygen or hydrogen peroxide as oxidant results in the partial dissolution of sulfides. While some of the sulfide sulfur is oxidized to sulfate, a considerable portion is oxidized only to thiosulfate and polythionates. Polythionates poison the ion exchange resin used to extract uranium. At the Palangana operation in south Texas, the trithionate ion (S3062-) was found by infrared spectrometry to be the major resin poison. Treatment of ion exchange feed solutions with hydrogen peroxide only resulted in partial conversion of reduced sulfur species to sulfate. Trithionate conversion was particularly slow. Poisoning of the resin also occurred from the ammonium chloride eluant, which built up trithionate because of recycling. This was essentially eliminated by chlorinating the eluant before yellow cake precipitation.

Jan 1, 1986

By Sheldon P. Wimpfen, Nelson Severinghaus

13.2-1. Introduction. Man&apos;s first association with industrial minerals came at the dawn of history when a remote ancestor first put a few rocks together to protect a fire or selected colored clays to decorate his face. He was dealing with industrial minerals when he selected flint to tip his arrows or scrape a hide. From that inauspicious beginning shrouded in the mists of man&apos;s earliest history, industrial minerals have grown tremendously in importance to our civilization. The growth rate of the industrial minerals, or nonmetallic group, has been considerably greater than that of the metals group, as can be seen by the following Fig. 13.2-1: [ ] Industrial minerals produced in the five-year period of 1961-1965 had more than twice the dollar value of the metals produced:

Jan 1, 1968

By C. A. Zapffe, C.E. Sims

Many hundreds of publications have appeared during the past 78 years that treat the subject of hydrogen in iron and steel.l05 but conclusions regarding the functions of hydrogen in causing some important defects in steel are still unsatisfactory to many; and other hydrogen-caused phenomena yet remain to be identified with this gas. The most widely discussed of these defects is hydrogen embrittlement, but the conception, perhaps the popular one, that embrittlelnent is due to hydride formation aoes not conform to the known facts.l04 The true identity of hydrogen embrittlement seems instead to lie in a mosaic nature of metal crystals, which is a concept not Yet accepted by most metallurgists. A study of hydrogen embrittlement therefore provides new viewpoints in regard to the crystalline substructure of steel.

Jan 1, 1941

By C. E. Sims, C. A. Zapffe

Many hundreds of publications have appeared during the past 78 years that treat the subject of hydrogen in iron and steel.l05 but conclusions regarding the functions of hydrogen in causing some important defects in steel are still unsatisfactory to many; and other hydrogen-caused phenomena yet remain to be identified with this gas. The most widely discussed of these defects is hydrogen embrittlement, but the conception, perhaps the popular one, that embrittlelnent is due to hydride formation aoes not conform to the known facts.l04 The true identity of hydrogen embrittlement seems instead to lie in a mosaic nature of metal crystals, which is a concept not Yet accepted by most metallurgists. A study of hydrogen embrittlement therefore provides new viewpoints in regard to the crystalline substructure of steel.

Jan 1, 1941

A shrinkage stope is an overhand stope in which the broken ore accumulates until the stope is completed to, or near, the level above. As broken ore generally occupies at least 60 per cent. more space than ore in place, about a third of this must be drawn out as the stope advances to leave a working space under the back. The ore remaining supports the miners and gives temporary support to walls, and is all withdrawn when the stope is finished. The shrinkage-stope method is applicable to steep-dipping deposits of strong ore with strong walls. It may be applied to narrow or wide veins, and is simple and cheap. Five examples, which include important and varied types of deposits, are given: namely, Kennecott, Homestake, Jarbidge district, Mogollon district, and Cripple Creek district.

Jan 1, 1925

By C. S. Cole

CO-CHAIRMAN CARTER S. Cole l-The stimulus of war definitely increases interest in the subject we are discussing at this Symposium. There have been, in the past, other symposia on this subject and there probably will be still others in the future, but I feel sure that this one will go down as one of the most important that have ever been held on the subject. In 1918 A.S.T.M. held a Symposium on Stress- Corrosion Cracking that was confined entirely to brass, because at that time few people were interested in the phenomenon as it applied to other metals. Again under the stimulus of war, we are gathered to discuss the subject, but this time brass alone is but part of our interest. It is interesting to note more papers on brass will be presented than there were in the 1918 session, but these brass papers, you will also note, comprise less than half our program. Aluminum, magnesium and

Jan 1, 1945

By P. J. Potter

PRACTICALLY all tin-base babbitt metals used in engine bearings are made to customers&apos; specifications, which are many and varied. The copper ranges from 3 to 8 per cent. and the antimony from 4 to 13 per cent.; generally, the babbitt with lower copper content will contain from 4 to 8 per cent. antimony and that with higher copper will have from 7 to 13 per cent. antimony. The allowable lead content varies from 0.20 to 2.00 per cent. If a solder is used as a bonding material instead of tin, the resulting material in the finished bearing will have a higher lead content, but it would not be enough to bring the lead above specificational limits. Impurities such as iron, arsenic and bismuth should be determined in the tin before using to insure a uniform and high-grade product. These points must be considered when segregating and grading the waste that comes from the finishing operations on lined bearings.

Jan 1, 1929

By A. M. Gaudin

MANY studies of comminution have been made to ascertain the size distribution of the product and to evaluate the work of comminution in the light of the size distributions of the feed and product. Up to now, these studies have been essentially statistical in character, that is, a certain lot of feed was subjected to comminution in some specified way, and the aggregate product was fractionated into sizes, thereby losing all knowledge of individual relationship of feed to product pieces. Radioactive tracers offer a means to do something in this respect which could not be done before, namely, to follow the rupturing of some particular piece in its normal environment of other pieces. That is, it permits going beyond the usual statistical limitations of size distribution studies to what may be termed a personalized or individualized study. The purpose of this paper is to present some preliminary experiments conducted with this tool.

Jan 11, 1951

In uranium metallurgy, the main purpose is to obtain a product containing 80-85% U308 (yellowcake) from ores whose average grade is a mere 0.21% U30& Essentially, the task of extraction and concentration involves dissolving the ore&apos;s U308 values, followed by purification and concentration of the uranium-rich solution (using such operations as filtration, clarification, and ion-exchange), and then selectively precipitating and isolating U308. Leaching is First Step In yellowcake production mills, the first chemical change occurs by leaching the ore with either sulfuric acid-as done by Anaconda and Kerr-McGee-or with an alkaline solution of, say, sodium carbonate, as done by United Nuclear-Homestake Partners. The choice of either acid or alkaline leaching is not an arbitrary one: it depends on the chemical and physical characteristics of a particular ore. That is, on the presence of clays, organic compounds (usually of carbonaceous origin), and soluble impurities, as well as on the ore&apos;s wetness and grindability.

Jan 8, 1974

By Hal M. Scrugham

UNITED States Steel Co.&apos;s Tennessee Coal & Iron Div. Wenonah mines present definite materials handling problems arising from the natural features of the operation. Trackless equipment went a long way toward supplying the answers-but at the same time gave birth to several new posers. Machines-trackless or otherwise-require maintenance and Wenonah&apos;s experience may do much to add to the body of information already available on this type of equipment. Let&apos;s look at the mines themselves. Ore is of sedimentary origin, extending over an area of several square miles. A thickness from 8 to 14 ft is mined. Bed dip varies from the horizontal to 20 pct in local rolls. Practice is to mine across the dip at 14 pct or less. A parting forms a smooth footwall in some of the mines while in others the footwall must be blasted smooth. Ore weighs 215 lb per cu ft in place and is extremely abrasive.

Jan 6, 1953

By John V. Beall

The Glidden Co., a newcomer to the mining industry, will be putting on stream its Lakehurst mine and concentrator this spring. Ilmenite-bearing placer sands will be mined and concentrated in a spanking new combination gravity, magnetic and high-tension separation plant. Glidden, well known as a paint, chemical and food manufacturer, consumes titanium dioxide as pigment in its paint business. The commodity is produced at the company&apos;s Adrian D. Joyce Works in Baltimore from ilmenite purchased in India and Australia, The Lakehurst operation, handily located in Ocean County, N. J., will dampen any deficiencies in quantity or price which might occur from foreign suppliers. This objective is no overnight concoction of The Glidden Co., because the move at Lakehurst was preceded by an attempt to start up in Florida. That project was abandoned when it was found that the titanium dioxide values were largely in rutile-a mineral which does not lend itself readily to the digestion process of the Baltimore chemical plant.

Jan 1, 1962