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By C. E. Schwab

A lead-zinc orebody, in fairly strong quartzite and with a dip of 35° to 60°, is block-caved by use of scrams in a stair-step pattern up the ore footwall. Scram linings to handle coarse muck and permit the use of folding scrapers are developed by the use of end-grain wooden blocks to reduce maintenance and keep operating cost to a minimum.

Jan 10, 1953

In cooperation with the United States Bureau of Mines and the Idaho Bureau of Mines and Geology, the University of Idaho offers in the School of Mines a number of fellowships. These fellowships are open to college graduates who have had good training in mining, metallurgy, or chemistry, and who are qualified to undertake research work. The income of each fellowship is $720 a year for the 12 mo. beginning July 1, 1919. Fellows will register as students in the University of Idaho and become candidates for the degree of Master of Science in Mining or Metallurgy (unless this or an equivalent degree has been earned). Their class work-will he directed by the heads of the departments of instruction, but the greater portion of their time will be spent in research work under the direction of the Bureau of Mines staff resident at the University. The purpose f this work is to undertake the solution of definite problems confronting the mining and metallurgical industries of the State of Idaho. For 1919-20 the following subjects are being considered: 1. Flotation-with especial reference to differential separation of various minerals. 2. Availability of western wood oils for flotation purposes. 3. Treatment of the complex gold-silver ores of southern Idaho. 4. Ore-dressing problems. 5. Mining problems. Applications, with certified copy of collegiate record, statement of professional experience, and names and address of three references, should be addressed to The Dean. School of Mines. Moscow Idaho_

Jan 6, 1919

By R. M. Waterstrat

The phase VPt has been reported to have a crystal structure of the B19 (AuCd) type at low temperatures.''' A recent investigation3 has indicated that this phase forms by an ordering reaction from the disordered fcc Pt(V) solid solution which is stable at high temperatures. olander4 has shown that there exists a close structural relationship between the orthorhombic B19 structure and a fcc structure possessing the L1 , (CuAu) type of atomic ordering. One may derive the B19 structure by a shear-like displacement of the atoms in the (002) plane of the ordered fcc lattice along the (010) direction through a distance equal to one eighth of the unit cell dimension, see Fig. 1, followed by an orthorhombic distor; tion of the cube axes such that a = 2.693A. h = 4.413A. and c =4.767A (estimated uncertainty 0.005A). Filings of this phase were produced by grinding a VPt alloy having the B19 structure with a diamond dental grinding disc. When these filings were subjected to X-ray diffraction examination, a pattern of a severely cold-worked fcc structure was obtained. higher solution temperature used (1200 C) or to a much lower oxygen pressure than he reported, due to transfer through many bends and tubes in his complicated apparatus. An interesting observation was made when an oxygen addition was attempted in a cylindrical sample of columbium in the cold worked condition rather than in the annealed condition. The interior of the sample re-crystallized during the oxygen addition at 900°C. The periphery, however. (1 mm) did not recrystallize. A similar sample without oxygen recrystallized throughout the entire cross section. It appears that the re-crystallization is hindered by interstitial oxygen. Presumably, the interior recrystallized before appreciable oxygen could diffuse into the core. This work was supported by the United States Atomic Energy Commission. When the filings were annealed in a high vacuum furnace for 15 min at 110O0C, however. they returned to the B19 structure perhaps as a result of reordering. Subsequent less-severe cold-working of these filings by grinding in a hardened steel mortar and pestle at room temperature produced a transformation into a cold-worked L1, structure which was slightly tetragonal. Thus it appears that the degree of deformation may influence the final structure. Considerable line-broadening was observed in X-ray diffraction patterns obtained from the cold-worked filings and therefore no attempt was made to obtain accurate lattice parameters. Vacuum annealing treatments at 1100'C intended

Jan 1, 1970

By William S. Dershowitz

INTRODUCTION Numerical methods commonly used in rock mechanics, such as finite element, displacement discontinuity, and boundary integral equation methods, offer solutions to problems which can be described by differential equations subject to boundary conditions. These numerical methods use approximations leading to solutions in terms of matrix algebra and numerical integration. Many rock mechanics problems which are beyond the scope of such approximations can be treated effectively by application of techniques developed in the field of artificial intelligence (AI). Among the possible applications are: site characterization (Duda, 1975), geological interpretation (Smith and Baker, 1983), solution of problems involving rock joint networks, and underground construction. Each of these applications utilize particular features of Al. Here we shall present results of AI applications which utilize primarily search and to lesser extent learning or pattern recognition. Specific examples presented are in the field of rock fracture network problems and underground construction. ARTIFICIAL INTELLIGENCE Artificial intelligence techniques attempt to achieve human-like reasoning and learning capabilities. This reasoning capability is valuable in applications where repetition, complexity, or tediousness makes human-like intervention impractical. In rock mechanics this occurs, for example, in stochastic rock mass modeling applications where some complex decision-making is required for each of a large number of iterations.

Jan 1, 1984

By James Norman

SPODUMENE is a lithium-bearing pyroxene, and is an important source of lithium compounds. Because of its high alumina and lithia content it might be a desirable constituent of glass batches. The use of spodu-mene in ceramics will undoubtedly increase, as it has been shown that a mixture of the proper proportions of this mineral with soda feldspar and potash feldspar has a much lower maturing temperature upon firing than has any one of the three components.1 The mineral spodumene seldom occurs as pure mineral, but ordinarily with feldspars, mica and quartz. All spodumene-bearing rocks tested contained these minerals as gangue. Small amounts of iron and manga-nese oxides also were present, usually as stains on the silicate grains. Mica associated with the spodumene carried a considerable amount of lithia. This was discovered in flotation tailings, which, although virtually free of spodumene grains when examined microscopically, showed 0.4 to 0.5 per cent Li20 on chemical analysis. The lithia content of micas picked from the North Carolina spodumene rock was variable. Some samples contained little lithia, others more than 3 per cent. In 1938, under the supervision of Oliver C. Ralston, ? the Bureau of Mines, in cooperation with the Tennessee Mineral Products Corporation, undertook to study the beneficiation of North Carolina spodumene by froth flotation. The Bureau had previously published investigations on the beneficiation of spodumene.2,3 The methods described in the second publication' did not give good results with badly weathered spodumene rock, so that more thorough investigation of the subject was warranted.

Jan 1, 1940

By Leon Keller, William R. Van Slyke, James Stukel

Two 4-ft wide DSM screens were installed during 1957 in one unit of the two-unit heavy media cy- clone section of the Holman-Cliffs concentrator at Taconite, Minn., following successful laboratory test work on a 1-ft screen. The two screens materially reduced the amount of media sent to the magnetic separator cleaning circuit. Wear life was good and fine size capacity was high. Briefly, the Holman-Cliffs heavy media cyclone plant uses -65 mesh magnetite as media and 10-in. diam., 30º Ni-Hard cyclones as separatory vessels. Feed to the plant averages 130 long tons per hr of -1/8 in. +65 mesh material. The conventional heavy media circuit uses drum or spiral type separatory units and treats +l/8 or 3/16-in. material. The medium is generally -65 mesh ferrosilicon. Ore and media are readily separated by screening at about 6 mesh. At this size, capacity is high and wear and maintenance are not excessive. The heavy media cyclone plant requires an efficient separation between +65 mesh ore and -65 mesh media. To reduce costs, however, the separation was made at a coarser size with the result that the media was un- duly contaminated and it was necessary to clean large tonnages of media and ore in magnetic separators. Due to the high capital cost of these units, their number was kept to a minimum and, consequently, they were overloaded. As a result, the separation between magnetic media and nonmagnetics was not sharp and the magnetite losses were high.

Jan 10, 1958

The American Museum of Safety has installed a large collection of exhibits at 18 West 24th St., New York City, and extends a cordial invitation to the members of the Institute to visit this exhibition. The Museum is open daily from 9 am. until 5 p.m., and special arrangements will be made for the admission of a large party in the evening. The exhibition covers all phases of industrial and general safety, and also the important questions of sanitation and hygiene.

Jan 2, 1917

By Raymond Brandon, Marshall Pease

A pattern for providing a large utility, The Detroit Edison Co., with an adequate fuel supply is outlined. From the standpoint of both fuel procurement and utilization, consideration has been given competition relationships, fuel properties as well as operating conditions that must be met to provide dependable service and reliable plant operation.

Jan 2, 1951

By K. J. Richards, W. J. Schlitt

A combination of industrial and laboratory data is used to explain the interrelationships between operating parameters and cementation plant performance as measured by copper recovery and iron consumption. The chemical factors considered are the relative concentrations of copper and ferric ions in solution, acid concentration, the possible buffering action of other dissolved salts and solution temperature. The effects of flow conditions, solution oxidation, the presence of metallic copper and retention time are also considered. Based on the various relationships developed, possibilities for plant optimization are discussed.

Jan 1, 1974

By Fred H. Lippold, Wm. H. Wolf

Methods of fair payment for excavating, supporting, and concrete lining tunnels have been sought by various owners for years. Tunneling techniques have changed with the development of equipment-from the hand-mucking operation to the machine mucker and, most recently, to machine-boring; from tunnel supports using timber sets to steel sets to rock bolts and, most recently, to shotcrete support; and from hand-placing the concrete lining using wooden forms to pumping or pneumatic placing using steel forms. As tunnel construction techniques advanced, so did methods for payment for the work performed. The recent development of tunnel-boring machines, or "moles," is precipitating another change. These changes have led to some difficulty in providing proper payment for the various items of work for different types of tunnels. As a major construction agency engaged in water-resources development in the western states, the U.S. Bureau of Reclamation has long been aware of the need for clarification of payment provisions in tunnel construction. The Bureau has some 150 miles of tunnels completed on its projects and about 50 miles of tunnels under construction. In this construction, the Bureau has benefited by the advance made by contractors in improving the techniques of tunnel excavation. To assure that the Bureau has an up-to-date approach to payment provisions, the Chief Engineer recently established a "standard" method of payment for all types of tunnels. It is believed that this new method of payment will be equitable for all contractors bidding on various types of tunnels using the diversity of methods of excavation now available to them. These payment provisions provide for different quantities for excavated tunnels using the blasting technique or using machine-boring techniques. In this way, the contractors have a choice in excavation methods and an equal opportunity to be low in their bids. We believe this will be an incentive to all contractors to be as progressive as the development of new equipment economically allows.

Jan 1, 1970

By Carl S. Westerberg

1,. C. McCABE*-—An increased derliand for coal in the west is to be expected because of the growth in population and industry during the past ten years. The author calls attention to the increased mechanical cleaning of Utah coal between 1938, when no cleaning was being done, and 194.7, when more than 24 pct of the production was cleaned. This is essentially the Period of most rapid growth of the Pacific Coast. area altliough the growth and, no doubt, the general trends in coal production and cleaning continued at a less accelerated rate during 1948. The Pacific southwest increased 37 pct in population between 1940 and 191.7 while the United States showed only a 7 pct increase in the same period. it has been estimated that there will be an additional 15 pct increase in population between 1947 and 1950. The conclusion that more coal and more mechanicak cleaning capacity will be required appears to be well founded. Mr. Westerberg discusses the cco- nomic advantages of coal cleaning reflected in freight savings, in lower cost per million Btu, and lowered ash and sulphur content. In view of the limited occurrence of coking coals in the west it would be interesting to know whether significant beneficiation in coking strength can be expected from mechanical cleaning of Utah coals. This has been demonstrated for some eastern and midwestern coals. One can readily agree to the desirability of recovering the fine coal that has heretofore been lost in washery slurry. The very cheapness of coal has Iridered

Jan 1, 1950

By S. FROES ABRUE

No new oil fields were discovered in Brazil during 1945. Production for the year reached a total of 79.329 bbl., all coming from the four fields in the Baia basin; the Lobato-Joanes field produced 6728 bbl.; Aratu, 6717 bbl.; Candeias, 36,663 bbl. and Itaparica, 29,211 bbl. The total cumulative production from the Baia basin from 1939 to 1945 inclusive amounts to 210,000 bbl., all of which is utilized locally.

Jan 1, 1946

J. S. UNGER,* Pittsburgh, Pa. (written discussion ?).-There is a common impression in the minds of many that forging or rolling apiece of steel not alone increases the strength but makes the steel more dense, or causes it to become heavier. I believe it is the author's aim in the paper to show that cast steel is almost as dense as forged steel. The average results obtained by him show very little difference in density, being

Jan 5, 1919

By Glenn M. Boyce

This paper discusses the results of a laboratory testing pro- gram to determine the validity of hydraulic fracturing stress measurements in salt. Tests were performed on 15 cm diameter samples loaded under hydrostatic stress conditions to determine the influence of time, confining pressure, flow rate, borehole diameter, and packers on breakdown pressure. Tests were also performed in a polyaxial loading frame to determine whether or not hydraulic fracturing could be used to measure non-hydrostatic stresses. The test results indicate that the breakdown pressure is not affected by time delays of up to 64 hours between the application of load and fracturing the rock. Breakdown pressures were found to fall short of predicted elastic values at higher confining pressures for the hydrostatic tests. The ratio of the horizontal stresses in non-hydrostatic tests had no effect on breakdown pressures. Flow rate and borehole diameter variations were found to have a marked effect on breakdown pressures. Shut-in pressure values, which are generally used as an indication of the minimum stress value, exceeded the applied minimum stresses by 10 to 60% depending on the method of determination used. The lack of a relationship between breakdown pressure and horizontal stress ratio may preclude hydraulic fracturing from being used in salt as it is conventionally applied in brittle rocks.

Jan 1, 1984

By R. D. Reiswig, D. J. Mack

THE use of pyrophoric alloys in ignition devices dates back more than fifty years to a German patent granted to Carl Auer von Welsbach in 1903.' This patent named a composition essentially the same as that used in most present-day cigarette lighter "flints:" 70 pct mischmetal, 30 pct Fe, referred to here as "Auer alloy." Among the few current exceptions to this composition are those "flints" based on titanium or zirconium. The rare-earth metals of which mischmetal is composed are so similar chemically and physically remarkable similarity in their alloying behaviors would be expected. Comparison of the binary phase diagrams2 of these elements with nonrare-earth metals shows that this is true to a striking degree, so much so, in fact, that it appears that a mixture of these elements may be treated as a single component of alloys without fear of serious error. In considering alloys containing mischmetal, therefore, the mixture of rare-earth elements will be referred to merely as "cerium," the predominant element in mischmetal. In polishing cerium alloys for metallographic examination, it was soon discovered that aqueous polishing media were highly corrosive. Free cerium in the alloys acts similarly to calcium (though not quite so rapidly) in evolving bubbles of hydrogen at the metal-water interface; thus, special metallographic techniques are required. The simplest polishing technique found to be satisfactory consisted of slow hand grinding on dry emery papers through

Jan 1, 1956

By C Gunther

Many definitions have been advanced and many limitations advocated in the use of the terms, veins, lodes and ledges. The following definitions appear to follow the best usage. A fissure vein, according to Lindgren, is a mineral mass tabular in form as a whole, though often irregular in detail, filling or accompanying a fracture or series of closely set and intimately related parallel fractures in the enclosing rock, the mineral mass having been formed later than both the country rock and the

Jan 1, 1932

By P. K. Foh, C. G. Dunn

IN an investigation of the rolling and recrystalliz-ing textures obtained from single crystals of Si-Fe, Koh and Dunn included specimens in the (111) [lie] orientation.1,2 This note reports some additional results obtained on samples of this orientation set aside for further study. After, primary recrystallization longer annealing treatments at 980°C produced only normal grain growth; after 16 hr at 980°C the largest grains were approximately 0.010 to 0.020 in. in diam. The orientations of 13 of the larger grains were found by the transmission Laue method. The unidentified (110) poles of these grains have been added to the (110) pole figure obtained after primary recrystallization2 to give the plot shown in Fig. 1. When grain identifications are also included, such a plot reveals the following. Two orientations agree almost exactly with the peak pole ,density positions of component B of the primary recrystallization texture, one with component A, and one with component C. All the remaining orientations except one have (110) poles near weaker and unidentified pole density peaks. In fact, the correlation is good enough for an identification of eight components. Previously only components A, B, and C were certain. The results are perhaps even more informative when combined with the (110) pole figure of the cold-rolled crystal to give the plot shown in Fig. 2. Each of the 13 orientations is identified and uniquely determined by selecting two (110) poles per crystal, which are 90" apart. The plot shows that every grain of the 13, except grain 6, has a (110) pole in common with a (110) pole concentration of the cold-rolled crystal. The orientation relationship with the cold-rolled orientation may be expressed as approximately 25" rotations about <110> axes, which is in agreement with the results found for coarse-grained primary recrystallization.2 If primary recrystallization had occurred according to the <110> rule without preference, there would have been 12 components. Actually our limited data reveals nine of the possible 12. The integrated pole figure also shows preferences among them, since three are considerably stronger than the rest. In addition to the above direct information, the following conclusions may be drawn. Primary recrystallization of the (111) [110] cold-rolled crystal produces a limited number of weak and strong components with the larger than average primary grains from these components related to the cold-rolled crystal by 25° <110> relationships. In arriving at this conclusion of limited orientations the (111) [110] orientation has to be ruled out as a source of large primaries for two reasons. First, growth in this orientation was not observed, despite an expected high grain boundary mobility (due to its 25" <110> relationship with every component of the texture). Secondly, primary recrystallization usually produces grains in new orientations, particularly in a single orientation matrix; but (111) [110] is not new. Other orientations besides those of the <110> type may be considered unlikely, of course, because the <110> relationship holds quite well for primary recrystallization2 and should produce the large primaries. There are exceptions to this rule, but probably not enough to provide large

Jan 1, 1958

By A. L. Holley

There are regularly manufactured in the eleven Bessemer steel rail mills of the United States, 119 patterns* of steel rails, of 27 different weights per yard. This list does not include patterns which, although still largely in use, are regarded by experts as obsolete, and which would swell the number to nearly 300; nor does it include all the patterns for which rolls are kept on hand to fill a passible demand; nor does it include extra patterns rolled in one finishing groove by opening or closing the rolls so as to get different weights with the same contours. The list embraces only those separate patterns which are subject to current orders. How thoroughly modern these patterns ere, is shown by the fact that of the whole 119, there are but five patterns of conspicuously bad shape; all the rest more or less completely illustrate the standard features,—a heavy head, light web and Hanges, and a good angle to hold the fish-plate. Sixty-two per cent. of the patterns have the "Chanute" head, which was not designed until 1874.† Sixty-four per cent. of the 119 patterns are embraced under five weights per yard,; three only of these vary from standard type; there are thus 76 patterns, all of them modern and standard, to represent five different weights, for which five patterns would perfectly answer. Of the 60lb. rails, there is only one of the pear-head type, while a dozen of the bevelled head templets cannot be distinguished from each other

Jan 1, 1881

By Norikazu Hashimoto

SILICIDE coatings on refractory metals are often applied by transporting a silicon halide vapor to a hot metal surface . The coatings are usually grown by solid-state diffusion reaction. The diffusion is often slower than the vapor transport and hence may become rate-controlling.

Jan 1, 1968

By L. J. West, R. M. Perrry

This chapter describes the rock mechanics studies performed for a high cut at a nuclear power station in Pennsylvania. Two units presently are being constructed on the Susquehanna River. When these units are completed, they will generate approximately 2100 MW of electricity. It was necessary to excavate about 1 million cu yd of rock to prepare the site. This excavation resulted in a high cut on the west and north sides of the station area with a maximum height of about 200 ft. The location of the high cut with respect to the plant facilities is shown on Fig. 1. The recommended slope angles ranged from 1 ½ (horizontal) to 1 (vertical) for the upper residual soil to ½ to 1 for the deeper competent rock. Because of the significant height of this cut and the fact that the slope is immediately adjacent to the proposed nuclear facilities, extensive stability analyses were performed prior to, during, and after excavation to evaluate the steepest angle at which the slopes could be safely cut. The studies consisted of evaluating both qualitatively and quantitatively all apparent factors which could affect the stability of the slopes. These factors include the strength of the material, the zones of weak material which are present along the planes of schistosity, the prominent joint systems, the ground water, and postulated seismic effects. FIELD AND LABORATORY STUDIES A comprehensive program of field explorations was performed to evaluate the geologic characteristics of this site. This program consisted

Jan 1, 1970