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Jan 1, 1931

By F. W. Aul, R. C. Glenn

EXTRACTION techniques are of particular importance in determining size, shape an: crystal structure of particles smaller than l000Å in steels and other alloys. However, artifacts that can arise during the preparation of extraction replicas may lead to erroneous conclusions. The purpose of this note is to illustrate some of these artifacts and the misinformation that can result from their presence. An alloy of iron with 0.8 pct Cu was investigated in the following conditions: 1) Solution treated 3 days at 925°C in dry hydrogen and quenched in water. Aged in steps to precipitate copper, as follows: heated to 700°C, held 1 day; then furnace cooled to 50O°C, held 3 days; then furnace cooled to room temperature. 2) Solution treated 3 days at 925OC in dry hydrogen and furnace cooled to room temperature. 3) Solution treated 3 days at 925OC or 17 hr at 1100°C in dry hydrogen to dissolve all copper, then quenched in water. A normal parlodion dry-extraction technique was employed after etching the specimens with super picralP or with 2 pct nital. A wet-extraction method

Jan 1, 1962

By John H. Stewart, Daniel R. Shawe

Major transverse structural zones in the western U.S. such as the Lewis and Clark line, Walker Lane, Texas lineament, and Colorado mineral belt, have localized important mineral districts. In Nevada and Utah the alinement of Cretaceous and Tertiary mineral deposits, such as in the Pioche, Eureka, Manhattan, and other mineral belts, may be related to similar tectonic features. All the mineral belts in Nevada and Utah have produced precious and base metals and tungsten; the Manhattan belt in addition has produced magnesite and brucite; and the Pioche belt, uranium, fluorspar, and alunite. Specific types of ore deposits seem related spatially to major belts of the Paleozoic Cordilleran geosyncline and compositionally to the intrusive bodies with which they are associated.

Jan 1, 1977

By Gilbert Thiessen

THE use of a pneumatic process for removing fine material (usually less than 48-mesh) is increasing in, the preparation of stoker-size coal. The fine material, produced as a byproduct, is known as dedusting-plant dust. Since fusain is the most friable ingredient in bituminous coal (it may readily be rubbed to an impalpable powder with the fingers), it tends to accumulate in this byproduct. While studying the properties of cokes produced by blending Illinois coals with other materials, considerable quantities of fusain were required. Dedusting-plant dust suggested itself as a-convenient supply. It became necessary, therefore, to determine how much fusain was contained in a measured sample of dust, how the fusain was distributed with respect to size and specific gravity in the sample, and whether or not it would be feasible or desirable further to concentrate or to recover the fusain from, the dust before using it in the blends to be coked. The results obtained indicate the possibilities of production of a high-fusain material.

Jan 1, 1936

By H. J. Beattie, G. C. Gould

J. B. Seabrook' recently published properties of a low-alloy Ni-A1 age-hardening steel known commercially as "Nitralloy-N". He mentioned three possible mechanisms of age hardening, viz. order-disorder in the matrix, order -disorder in a precipitate, and a precipitate that goes in and out of solution reversibly without losing coherency. The following results indicate that the last - mentioned of these mechanisms is the cause of age hardening in Nitralloy-N. The reversibility of the age hardening with a sub-critical solution temperature was demonstrated strikingly by Seabrook, whose results are reproduced in Fig. 1. Aging for 22 hr at 975°F (525°C) can reharden the fully-tempered martensite to its original as-quenched hardness of R, 45. A Nitralloy steel was obtained from Seabrook' with the following analysis:

Jan 1, 1962

By D. W. Brunton

The object of the investigations and experiments here recorded was to obtain such information and data as would make it possible to determine the fineness to which crushing must be carried, in sampling gold- and silver-ores, in order to obtain results within an allowable limit of error.

Jan 1, 1896

By D. E. Swets, P. C. Frank, D. L. Fry

THE hydrogen-steel system has received considerable attention in the past several years. Recent experiments in this laboratory have shown that another group of operations, namely, sanding and grinding,' must be added to the already well-estab- lished list of phenomena that cause hydrogen to permeate steel. Qualitative tests which have been made with a very sensitive ion-gage type of detector similar to that used by Norton,' showed that sanding a steel surface caused hydrogen permeation. A metal type 6~6 vacuum tube was used as the ion gage with an electrometer to measure the ion c~rrent.~ The protective enamel coating was removed from the tube.

Jan 1, 1959

By W. L. Dudley

It is my desire to call attention to a new industry which was started about four years ago, through the discovery by Mr. John Holland, a resident of this city, of the methods employed in working the metal iridium. This metal has been known since the year 1803, having been discovered by Smithson Tennant while investigating the metallic residue which remained when platinum ores were dissolved in aqua regia. The metal is classed among the rare metals, as it is not found in large quantities, although it is quite widely distributed geographically. It is found in California, Oregon, Russia, East India, Borneo, South America, Canada, Australia, and in certain parts of France, Germany, and Spain. The principal sources of supply of the metal are Russia and California; it is nearly always found with either platinum or gold, is extracted from those ores as a by-product, and is always found in small grains or fine powder, the largest pieces being about the size of a grain of rice. In nature it is generally alloyed with other metals, and the two metals with which it is most commonly alloyed are platinum and osmium; the platinum alloy is called platin-iridium, and the osmium alloy osmiridium, or iridosmine. The grains of platin-iridium are

Jan 1, 1884

By J. C. M. Li

This exploratory survey was undertaken to repeat some experiments- in which anomalous results were reported1 for bismuth and to measure the thermoelectric power of some bismuth alloys and inter-metallic compounds. sato1 reported that the thermoelectric power of bismuth depends on the temperature gradient. This seems rather unreasonable especially when the Benedicks effect' has not been detected. Even if the material is not homogeneous, the observed thermoelectric power can be represented by

Jan 1, 1959

By Walter Morley

This paper is a record of the first of a series of tests on sulfide minerals to be made by the metallurgical department f the University of California. The purpose of the tests here recorded is to determine the action of standard oils, oil mixtures, and addition agents on the flotation of pyrites. The question of the commercial value of pyrite was not considered. Of the many factors affecting flotation, only two-the oil and the other agent used-were made variable. The flotation agents used are given in the accompanying table. PENSACOLA TAR AND TURPENTINE CO. (PENTARCO) NON-POL., SP. Dis. REF. PER No. KIND GR. POINTS INDEX ?VISC. CENT. 200 Refined wood creosote oil 0.965 105-275 1.5096 1.7 7-8 350 Crude pine wood oil 1.019 70-345 1.525 2.9 4 75 Crude wood turpentine 0.887 65-217 1.456 0.9 10-12 80 Crude pine oil 0.911 70-232 1.4894 1.1 8 750 Heavy pine tar oil 1.063 165-350 1.557 41.0 400 Wood creosote oil 1.025 190-360 1.4977 2.9

Jan 7, 1921

By D. F. Strong

Most Newfoundland mineral deposits can be clearly classified as within rocks formed either as accreting plate margins (ophiolitic pyrite-chalcopyrite massive sulfides such as Betts Cove, Whalesback, York Harbour, chromite at Lewis Hills, and asbestos at Baie Verte), at consuming plate margins (Kuroko-type polymetallic massive sulfides such as Buchans and Pilleys Island, porphyry-type Mo-Cu at Rencontre, fluorite at St. Lawrence), or within plates (zinc deposits at Daniels Harbour, sedimentary iron ores at Wabana, manganese in Conception Bay.) As these metallogenic patterns can be convincingly extrapolated southward into the Appalachians and northward to the Caledonides, they provide an important means of eliminating and selecting areas for particular exploration targets. Some criteria are described for the recognition of these environments of differing economic potential.

Jan 1, 1975

By Robert Stefanko

Roof bolting in coal mines has progressed very rapidly in the last decade, and today this method of support is in general use. There are many theories concerning the functions of roof bolts, but the importance of beam building is indisputable. Proper tension in the bolts minimizes shearing along bedding planes and creates a thick, competent beam from individually weak layers. Bolting must be accomplished immediately upon exposure of the roof, and bolt tension must be maintained if roof failure is to be prevented. Seams are being mined today with roof bolt support where conventional timbering was not effective1. The widespread use of continuous mining equipment was made possible by roof bolts which permit long supported spans free of obstructions.2 Since adequate anchorage is the key to successful bolting, better methods for determining the efficiency of anchorage are continually being sought. Attempts have been made to measure bolt loads, thus assessing anchorage efficiency by employing sensing devices between the bolt head and roof. 3,4,5 None of the techniques appears to be very accurate, and all have at least one serious deficiency.

Jan 5, 1962

By R. E. Reed, R. D. Leggett, Paxton, H. W.

TECHNIQUES have been developed for growing monocrystals and bicrystals of Fe-20 Cr, Fe-20 Cr-20 Ni, and Fe-18 Cr-8 Ni alloys by both the strain-anneal and the Bridgeman techniques. None of the techniques are new but since they are simple and many people have expressed interest, they are described here quantitatively as they could be modified for other single-phase "commercial" materials of high melting point. CRYSTAL GROWTH BY STRAIN ANNEAL Flat tensile specimens with a tapered gage length were initially studied to deduce the approximate critical strain. Normal flat tensile specimens were then used. The optimum procedure for the austenitic steels (Fe-Cr-Ni) deduced from a variety of cold reductions, recrystallization treatments, tensile strain, and growth anneals was as follows: cold reduce 70 pct, recrystallize (after machining tensile specimens) at 1000°C for 1 hr, strain in tension 2.5 pct, and then heat to 1350°C as rapidly as possible. A time of 100 hr at 1350°C is usually sufficient to pro-

Jan 1, 1960

By Richard F. Miller

The investigations of large-grained specimens carried out by Polanyi and Schmid,l Sykes,2 Goucher,3 Yamaguchi,4 Gough, Cox, and Sopwith,5 Carpenter and Elam,6 Aston,7 and others have shown qualitatively that grain boundaries restrain the deformation of adjacent crystals. But whether or not the influence of the grain boundary is confined to the glide planes intersected by the boundary has not been demonstrated in any of these investigations, nor has there been carried out any quantitative analysis of the influence of a boundary on the deformation of a crystal. Indeed, the specimens employed in the previous work contained so many complicating factors that it would have been difficult to observe any variation of the extent of the influence of the grain boundaries in relation to their sizc. The specimens were small, the grain boundaries irregular and at no particular angle to the specimen axis or the

Jan 1, 1934

By J. T. Eash, E. M. Wise

MANY of the platinum metal alloys are hot-forged in the early stages of reduction from ingot and substantial quantities of platinum alloys are commercially employed at very high temperatures in ammonia oxidation units, orifices for forming glass rods and fibers and as cathodes in long-life thermionic amplifiers. They are used also for electrical heating resistors, safety blowout disks, thermocouples and crucibles. The tensile properties at elevated temperatures are important in many of these situations but data on the subject are limited. Creep data also are important, but will not be covered at this time. SCOPE AND CONCLUSIONS Tensile tests were carried out at room temperature and elevated temperatures up to 11000 C. on previously well annealed samples of platinum, palladium and several of their important alloys with compositions shown in Table 1. The results are presented graphically in Figs. 1 to 4. The tensile strengths of platinum and the platinum-base alloys (with the exception of the 10 per cent rhodium-platinum alloy) at 1100° C. are from 16.6 to 18.8 per cent of the strengths of the same alloys (well annealed) at room temperature. The strength ratio of the 10 per cent rhodium-platinum alloy is 22.3 per cent, which is appreciably higher than that of the- other materials tested. The tensile strengths of palladium and the palladium alloy at 1100° C. are from 10 to 11.2 per cent of the room-temperature values. The elongations of platinum and its alloys tend to increase at tempera¬tures above 600° to 800° C., while the two samples of pure palladium show a maximum at 600° C.

Jan 1, 1938

By R. E. Hook, H. J. Garrett, A. M. Adair

X-ray diffraction and metallographic techniques were employed to examine the impurity phases occurring in as-swaged and recrystallized chromium produced fvom high-purity iodide chromium crystals. Chromium oxides are found to form in a consistent manner associated with the temperature of recrystallization. Microscopically observable second phase particles of Cr203 are observed to form intergranulurly beginning at 1300T. Beginning at 1500°C. Cr30, is formed intergvanulurly, atzd at 1600°C and above Cr30, is also formed in association with migrating grain boundaries. Geometrical traces formed by particles of this high temperature oxide uithin the grains rez)eal the histmy of grain boundary motion. X-ray evidence is presented which suggests the existence of a high temperature form of Cr203. Other impurity phases in addition to the oxides of chromium are also present. THE partitioning Of impurity elements between grain boundary aid lattice sires, either as solutes in solution or as second phases, may exercise an important influence on the mechanical behavior of metals and alloy systems. This partitioning of impurities could have a direct bearing on the iecrys-

Jan 1, 1963

By John L. Burnett

Manufacture of lightweight concrete aggregate from common shale is one of the most rapidly growing industries in the field of nonmetallic or industrial minerals. Although expanded shale" has been in use since it was developed by Stephen J. Hayde in 1917, it was not until after World War II that it became a substantial competitor with other aggregates. There are some 70 plants now producing this aggregate in the United States, approximately half of them in states west of the Mississippi River. Expanding plants throughout the U. S. are grouped around major urban centers such as Los Angeles, New York, Chicago, and Denver. Concrete made with expanded shale aggregate combines the desirable features of low weight with relatively high strength, making it especially useful in concrete block, in structural concrete for multi-story buildings and in a variety of specialized concrete products such as prestressed panels and beams, and storage tanks. As the cost of construction continues to rise, lightweight concrete will probably be used in increasing quantities because of its low cost relative to the more traditional construction materials such as wood, brick and steel

Jan 1, 1964

By Charles M. Cooley

In these troubled times free enterprise is maintaining vital molybdenum output, while expanding plant, and bringing in new low grade ore reserves, at Climax, the world's largest known molybdenum deposit. Climax Molybdenum Co. is putting $25 million into additional surface plant facilities and other millions into underground development. The expansion program to be operating by 1954 includes a new mining level, crushing plant, 4000-ft conveyor, milling units, by-products plant, and housing for 198 families. Completion of this program and low grade plant will add 10,000 tons per day to present capacity and several million tons to ore reserves.

Jan 1, 1953

By Arthur W. Griffith

Ozark Lead Company, a wholly owned subsidiary of Kennecott Copper Corporation, was formed in 1961 to operate in the State of Missouri. The orebody presently being mined was discovered in January of 1962, and over a quarter of a million feet of drilling was done to determine its value and extent. In addition, a development shaft, six feet in finished diameter, was drilled into the orebody by an oil field rig in order to support the results of the core drill samples and to obtain bulk samples of ore for metallurgical pilot plant testing, upon the results of which the primary flowsheet was established. The design criteria developed from the flowsheet was based upon a 6000 TPD plant throughput and the subsequent engineering and construction of the mine and concentrating plant was completed in June 1968. The plant, which is designed to mine and mill 6000 tons of ore per day and produce 60,000 tons of lead and 8000 tons of zinc in concentrate annually, is located approximately 110 air miles south- west of Saint Louis. MINERALOGY The orebody occurs in the Bonneterre dolomitic limestone formation in the form of irregular masses of disseminated sulphides in essentially horizontal beds. The Lamotte sandstone underlies the Bonneterre formation and is barren in values. Principal ore minerals include galena with lesser amounts of sphalerite and some copper minerals. Galena is found to be massive

Jan 1, 1970

By A. S. Malicsi, R. J. Lipp, I. Iwasaki

A loch-grade copper-nickel deposit, with an estimated 4.6 Gt (5 billion st) and average analyses of 0.6% copper, 0.2% nickel, occurs in northeastern Minnesota. In addition to copper, nickel, cobalt, and precious metals, the Duluth gabbro contains magnetite, ilmenite, olivine, plagioclase, and biotite. It u estimated that flotation tailings that would be produced by a concentrator of optimal size to sustain a smelter would amount to 20 Mt/a (22 million stpy). The flotation tailings, having already been ground, warrant a closer examination for recovery and use of potential byproducts. Residual sulfide minerals and fibrous minerals may also be isolated and treated separately for useful purposes or for disposal in an environmentally acceptable manner. Two flowsheets were developed; one involving preconcentration by low- and high-intensity magnetic separation and another involving preconcentration by gravity concentration. Concentration methods for recovering and purifying individual byproduct minerals were investigated. From their chemical, physical, and mineralogical characteristics, the potential areas of application and marketabilities of each product fraction were surveyed.

Jan 1, 1985