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By T. D. Murphy, G. V. Henderson

The element silicon, with its usual partner, oxygen, plays the same role relative to inorganic materials as carbon and hydrogen play with respect to living organisms. The crystallographic structure of silicon dioxide (SiO2) consists of one atom of silicon well-nigh inseparably bonded to four contiguous atoms of oxygen, a gas of but slightly more than half its atomic weight, forming a three-dimensional network of SiO4 tetrahedra (Dietz, 1968). This wispy arrangement is the fabric of the mineral quartz which is one of the harder, more abrasive, and chemically stable raw materials to be found in Mother Nature's cupboard. Most of us are vaguely familiar with the observation that nearly 60% of the lithosphere to an approximate depth of 10 miles is composed of these two elements, which proportion actually rises to about 75% if the atmosphere, hydrosphere, and biosphere are included (Parker, 1967). Elemental silicon is a brittle steel-gray metalloid with a density of 2.42 and does not occur in nature. In its limited commercial form, which is still brittle and metallic in appearance, its density drops to 2.33. It combines with oxygen to form the gaseous oxide SiO, or the solid dioxide Si02 (analogous to its congener carbon in CO and CO2); a tetrachloride SiCI4 (analogous to CC14); or, combining with oxygen and one or more metal ions, forms the largest rock-making family of all, the silicates. Further, next to the feldspars, quartz is the most abundant known mineral and, in some form or another, accounts for roughly 12% of surficial terrestrial rock. It is this so-called "free silica" to which your attention is chiefly directed in this chapter. In any such consideration of silica, its several crystalline phases with their attendant differing physical properties appear worthy of delineation. Alpha quartz is the only one of this interesting polymorphic family that is thermodynamically stable at normal pressures and temperatures up to about 573°C. The low phases of tridymite and cristobalite can exist in the so-called metastable state below 117° to 200ºC but seldom occur in nature in these two different crystal forms (Sosman, 1965). Opaline silica, now considered by most researchers to be a variety of cristobalite, occurs in abundance and is the only exception. The three remaining polymorphs, keatite, coesite, and stishovite, also are metastable under ambient conditions. Keatite, however, is not known to occur naturally and has only been synthesized in the laboratory. The other two have been identified in submicron sizes and in microscopic amounts, occurring naturally as a result of high order shock-wave pressures generating quite elevated temperatures --such as might accompany the impact of a large meteorite on a hard sandstone terrain (Chao et al., 1962). An intriguing characteristic of these silica minerals, and one which has very practical applications, is their extremely variable densities. The classic 2.65 specific gravity of alpha quartz drops to 2.20 in tridymite, cristobalite, and lechatelierite (natural silica glass), as well as in many man-made glasses of commerce which are merely noncrystalline or amorphous solids in the form of super-cooled liquids which can no longer change their shapes (Pauling, 1950). It rises again to 2.50 and 2.93 for keatite and coesite, respectively, and finally becomes a reported 4.35 for stishovite-nearly a 50% range in density for the known physical combinations that silica naturally assumes (Frondel, 1962; Konnert et al., 1973; Pecora, 1960). Pursuing its esthetic aspects, briefly, silica is well-represented among gem stones which, to qualify as such, must have the attributes of beauty, durability, and rarity (Jahns, 1983). As quartzose gems usually have but one or, at

Jan 1, 1983

By George A. Guess

The making of contracts for the purchase of ores is a business which the metallurgist usually understands better than the miner. Companies in the custom ore business often employ an ore buyer who is aware of the class of ore which the smelter needs, and is thoroughly conversant with the business. The miner on the other hand makes ore contracts but seldom, and it is often only after a settlement has been made that he realizes the meaning of the terms of the contract under which he has sold his ores. He has expectations usually greatly in excess of the amount 'net proceeds' shown at the bottom of the settlement sheet. Seldom does the occasional shipper really know his contract. A somewhat similar parallel is to be found in insurance policies. We all have insurance policies; we never know the conditions contained in them until after the fire. The clauses in the policy are for the protection of the Insurance Company. An Insurance Company has no friends.

Jan 1, 1926

By W. Hunka

PACIFIC PETROLEUMS, Ltd. first discovered commercial quantities of gas in the Peace River area in 1952. Development of gas wells in this area is quite ex-pensive due to low penetration rates. To improve the economics, the potential of the wells in many cases had to be increased. At that time, well stimulation was still in its infancy in Canada and in this area, in particular, no treatment of any consequence had been attempted. Therefore, trial-and-error was the only means available to determine the stimulating technique that would give optimum results. Various fluid treatments were available and these were used wherever the application was warrant-ed. This paper covers acid fracture and explosive treatments as carried out on various gas-bearing horizons.

Jan 1, 1958

By Hilde TWC

Synthesis of GLORIA side-scan sonar and other geophysical data has provided morpholo- gical and tectonic details of the interaction between the Nazca and South American plates along the Peru Trench (80S-15¦S). Our analyses suggest that a new propagating rift of the Galapagos type is evolving along the Mendana Fracture Zone (MFZ). Subduction induced rift- ing of the Nazca plate is accompanied by organized seafloor spreading for the last 3 Ma at least. GLORIA sonographs and bathymetric mapping show an 8-10¦ divergence in MFZ width towards the Peru Trench. The fracture zone comprises numerous ridges and troughs and a lack of sediment cover in the axial part. Young magnetic lineations (anomalies 1-2A) are observed within the fracture zone wni.cn are orthogonal to the older Nazca plate lineations. The central anomaly narrows west- ward and can be observed up to 400 km seaward of the trench whereas anomaly 2A is terminated about 200 km from the trench axis. Recent SeaMARC II sonar mapping in the region shows large igneous blocks in the Trench axis to the north of MFZ but absent to the south. We believe these blocks represent young seafloor of MFZ rift/spreading center broken off from the ridges as they subduct along the Peru Trench. The MFZ rift is propagating west- ward at a rate of 115 km/Ma (25 km/Ma relative to the South American plate). Given the present rates of accretion at the East Pacific Rise and of propagation along MFZ rift, the Nazca plate will be divided into two parts in about 35 Ma.

Jan 1, 1987

By B. C. Raynes

IN the early part of 1952, under the auspices of the U. S. Atomic Energy Commission, Horizons Inc. undertook an investigation dealing with the preparation of high purity thorium metal in order to develop an economically competitive production process for this metal based on a recovery of the metal by a fused salt electrolysis, since a survey of the literature of thorium chemistry indicated that electrolytic methods had not received much attention, despite the consideration that electrochemical production methods often offer attractive commercial potentialities. Thorium metal has been prepared by methods which fall into four general categories: 1) reduction of halides or double halides; 2) reduction of the oxide; 3) thermal decomposition of halides; and 4) electrolytic methods. Some of the important results obtained by various investigators since about 1900 in recorded attempts to prepare pure thorium metal are summarized in Table I. A bibliography of pertinent literature is included in this paper. Thorium is strongly electropositive and possesses a great affinity for oxygen and nitrogen. As a result the prospects for the production of high purity thorium from aqueous media or oxygen bearing compounds are remote. The most promising and profitable area of investigation for production of thorium metal lies in fused salt electrolysis. Thorium has been produced previously by this technique from halide salts in fused alkali chloride eutectic mixtures. Until recently, however, the lack of known large uses for thorium has inhibited the investigation of these methods. The basic problem in an investigation into fused salt production methods for thorium is to develop a suitable fused salt system for the economic preparation of thorium. The first portion of the work in these laboratories was a small scale investigation of the electrolysis of potassium thorium fluoride, KThF5, under a variety of conditions. High purity thorium was prepared in this manner, but the process did not appear to offer the simplest and most attractive continuous commercial operation. The work reported here relates to an all-chloride system employing thorium chloride as the cell feed. ThCL4 was produced as an anhydrous material stabilized in molten sodium chloride. This product, further diluted in NaCl, was subjected to electrolysis. The electrolytic process has been studied in cells capable of holding up to 50 lb total salt charge. Ductile, pure thorium metal has been reproducibly obtained in this operation. Considerable experimentation was carried out in the preparation of ThCL as a cell feed free from moisture, oxides, and other impurities. Thorium was cathodically deposited as a coarsely crystalline powder interspersed with residual bath salts. Aqueous procedures for separating and recovering the metal were developed. The thorium metal powder obtained has been evaluated with respect to its hardness, chemical purity, and certain other physical properties. Preparation of ThC1,—Thorium chloride, and the chlorides of some other metals (aluminum, beryllium, tantalum, zirconium, etc.) cannot be obtained from aqueous solution by direct heating and evaporation. Evaporation and heating of a solution of thorium chloride yields a hydrated salt or partially hydrated salt, and finally Tho,. Anhydrous thorium chloride is obtained by forming a hydrated ammonium chloride complex salt in acidified water solution, dehydrating this compound, and finally decomposing the double salt and subliming the ammonium chloride component. Various methods for the preparation of anhydrous thorium chloride, in accordance with this concept, were investigated as indicated in Table I1 from hydrated thorium chloride (ThCl, . 3H2O), and from thorium oxycarbonate (ThOCO,). In the method found most satisfactory for this work, thorium oxycarbonate was dissolved in an excess of concentrated HC1 to give a clear yellow solution. At least 2 mol NH,Cl were added to the solution per mol of contained thorium. Ammonium thorium chloride hydrate was crystallized from solution by cooling and saturation with HC1. The resultant complex, (NH,Cl),ThCl;xH,O, was dehydrated by evaporation at 130° to 150°C and thoroughly dried at about 250°C. The dried ammanium thorium chloride was then mixed with sodium chloride in proportions to form NaThCL or to produce a ThCL4-NaCl mixture with a given thorium content. The ammonium chloride was sublimed off at temperatures above 500°C in an inert atmosphere furnace to give an anhydrous chloride source electrolyte, essentially free of Tho, and of NKC1.

Jan 1, 1958

By Marc Symbaluk

Core Programs Current ? Aboriginal Involvement Program ? Adaptive Forest Management / Forest History Program ? Grizzly Bear Research Program ? Natural Disturbance Program ? Foothills Growth and Yield Association ? Foothills Stream Crossing Program ? Fish and Watershed Program ? Caribou Landscape Management Association ? Social Science Program ? Local Level Indicators Program ? Communications and Extension Program ? Geographic Information Systems Program ? Mountain Pine Beetle Ecology Program In Development ? Climate Change Program ? Forest Community Program ? Water, Quantity and Quality Program (Water for Life) ? Circumboreal Initiative ? Yellowhead Ecosystem Management Group

May 1, 2008

By P. R. G. Bak

The integration of interactive computer graphics technology with data analysis tools can assist in the evaluation of deposit models: the super- imposition of mine openings on complex geology can be quickly perceived using dynamic visualisation, colour-coding and transparency control while analysis functions assist in quantifying displayed information. To illustrate the functionality of such integration a research prototype system is presented which allows the interactive visualisation and evaluation of deposit models comprising both structural boundaries and the distribution of continuous properties.

Jan 1, 1992

By Denton A. Kort

Historically the visual examination of drilled shafts to determine shape was typically done under dry conditions. Many engineers believe that by using a dry method of construction, the question of shape is minimized because they can visually examine the excavation. In fact, test data suggests that slurry stabilized shafts tend to perform better than similarly constructed dry shafts. Clearly, the uncertainty of the shaft shape is magnified when constructed under slurry. Recent advancements have allowed a mechanical caliper to determine shape in wet conditions, but can be limited by certain shaft anomalies. New sonar technology can determine shaft shape, volume and verticality. The value of sonar technology to the geotechnical and foundation industry at large in terms of quality assurance for clients/owners and quality control for drilled shaft contractors is significant. This presentation will discuss the development and process of sonar calipering technology as it relates to the geotechnical and deep foundation industry. Sonar calipering results presented may include images from the following types of projects: slurry walls, bridge piers, cofferdams and secant walls. The results identify shaft anomalies in a variety of slurry environments, from water and polymer mixes through mineral slurries. Real-time in-situ images and CAD drawings will be presented illustrating the advantages of good caliper data taken during construction. This presentation will appeal to the geotechnical and structural engineers, as well as those supporting the deep foundation industry at large.

Jan 1, 2007

By Carl Henrich

Jan 1, 1890

By F. N. Earll

4.1 – DEFINITIONS 4.1.1-MINERALS, ROCKS, ORES AND NONMETALLIC MINERALS F. N. EARLL A mineral is a naturally occurring inorganic element or compound. Most minerals are distinctly crystalline in habit, and many commonly occur in well-formed crystals or crystalline aggregates, but a few species are characteristically amorphous or noncrystalline. Nearly 2,000 mineral species are now recognized but, perhaps fortun¬ately, a rather large proportion are rarely encountered. Even so, the application of modern mineral-detection and identification techniques reveals the presence of surprising numbers of mineral species, even in deposits of outwardly simple mineralogy. A rock is an aggregate of grains or crystals of one or more minerals. Some rocks are essentially monomineralic. Thus, limestone consists largely of the mineral calcite, and many sandstones are dominantly quartz. Most rock varieties, however, contain a number of mineral species, and their classification or identification depends upon the minerals present, their relative abundance, and such factors as rock tex¬ture and origin. Ore is defined as an accumulation or deposit of one or more minerals that can be exploited at a profit. The profit criterion commonly is taken somewhat liberally, however, for, although always present, the specific mineral content that constitutes a viable product is transitory. The term ore, usually, but no longer consistently, is restricted to the description of mineral deposits that are of value for their metal content. Nonmetallic deposits, although similar to metallic ores in many respects, generally are valued for the minerals or compounds present, as with rock salt (halite), rather than for individual contained elements, though such minerals as elemental sulfur are of much value. 4.1.2-ROCK TYPES F. N. EARLL Rocks arc grouped tinder three broad headings: (1) igneous rocks formed by the crystallization of magma; (2) sedimentary rocks formed by surface processes of weathering and deposition; and (3) metamorphic rocks, which may have been derived from either of the foregoing, but have undergone important physical and/or chemical changes through the application of heat or pressure, or both. The three groups can he further subdivided for convenient reference. Thus, igneous rocks are described as being abyssal or plutonic if formed at great depth, hypabyssal if formed at intermediate depth, and extrusive or effusive if formed at or on the earth's surface. The sedimentary rock group is similarly subdivided into clastic sediments and chemical precipitates. The clastic sediments form by deposition of preexisting minerals that were released from their place of origin by weathering and were transported to their point of deposition as discrete grains

Jan 1, 1973

Airy kind of a power system is a complicated network of various electrical components, such as cables, transformers, electric machines, circuit breakers, etc. For a system to work continuously and efficiently, each of the components has to be in perfect operating condition. The failure of any of these components can cause serious interruption of the supply and may in several cases involve a lot of precious time and labor in removing and replacing the damaged equipment it may also give rise to dangerous overvoltages on the system, thereby causing a safety hazard. Any piece of electrical equipment can have two likely modes of failure. The first would be the degradation of solid insulation material due to overheating, mechanical damage or a combination of the two, In this mode of failure it is possible that If the insulation damage is not an instantaneous phenomenon (a cable damaged by severe mechanical, Stress) that a detectable leakage current will do lop prior to the faint. The fault would probably he a result of heating and deterioration of the insulation by the leakage current.

Jan 1, 1975

By J Ward, B Rohrlach, B Rosero, J Silva, O Poma

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Alpala copper-gold deposit is a recent, high-grade porphyry Cu-Au discovery located in the Imbabura Province of north-western Ecuador. The deposit lies along the crustal-scale Chimbo-Toachi Fault Zone within the Dagua-Piñon terrane, which is an oceanic plateau accreted to the South American convergent margin in the Late Cretaceous. The deposit is hosted by quartz diorite stocks that intrude andesitic volcanic breccias of the Oligocene to mid-Miocene San Juan de Lachas Formation. Miocene-age calc-alkaline plutonism is associated with porphyry Cu, Cu-Mo and Cu-Au deposits in southern and northern Ecuador. The Alpala deposit lies along a sector of the Miocene arc that has recently been underplated by the Carnegie Ridge seamount chain that induced shoaling of the subducted Nazca plate beneath northern Ecuador.Surface expressions of the deposit were recognised in May 2012 during follow-up of stream sediment anomalies, when outcropping sheeted and stockwork porphyry-related veins were discovered in Quebrada Alpala. The roots of a NW-trending, structurally-controlled lithocap were recognised over an area of 4.5 × 0.9 km. The remnant lithocap exhibits well-defined mineral zonation mapped by TerraSpecTM analyses on grid soil samples. Soil sampling, heliborne magnetic surveying and channel sampling defined initial drill targets.Seven diamond drill holes were completed in the year from September 2013. Drill hole CSD-13-005 intersected 672 m grading 0.93 per cent Cu and 0.91 g/t Au in high-temperature, inner propylitic and locally potassic-altered quartz diorite intrusions. Overlying hydrothermal clay alteration assemblages define the base of the lithocap. A NW–SE trending footwall structure defines the south-west margin of the deposit. Drill hole 5 intersected high-grade sheeted ‘B-type’ and ‘C-type’ veins (Gustafson and Hunt, 1975) that lie along the south-west margin of an 1100 × 500 m magnetic anomaly that is the focus of ongoing exploration.CITATION:Rohrlach, B, Poma, O, Rosero, B, Silva, J and Ward, J, 2015. High-grade porphyry copper-gold mineralisation in north-west Ecuador – The Alpala Cu-Au porphyry discovery , in Proceedings PACRIM 2015 Congress, pp 369–376 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By D. Harrington

This paper is a revision of Information Circular 7380, by D. Harrington and J. H. East, Jr., published in 1946, entitled ?Safe Storage, Handling, and Use of Commercial Explosives in Metal Mines, Nonmetallic Mines, and Quarries.? Issued soon after the close of World War II, this earlier circular described the unprecedented increase in the production and use of commercial explosives during the war as a result of expanded industry and the tremendous demand f or metals and minerals. In the years following World War II, the production and use of commercial explosives in the United States have continued to rise. Hence, the Bureau of Mines presents these revised figures through 1952. In rewriting this Wormation circular, most of the text prepared by Harrington and East has been retained, with newer statistical information compiled by Seth T. Reese, Accident Analysis Branch, and V. E. Wrenn, of the same branch.

Jan 1, 1954

By Juan G. González Rojas

El presente estudio describe los resultados de exámenes sobre salud ocupacional en nueve asientos mineros del Perú, pertenecientes a los departamentos de Arequipa, Ayacucho, Cusco y Puno. El trabajo comprende dos partes: el ambiente ocupacional y el estado de salud del personal expuesto. Asi también se informa sobre la seguridad, aspectos de saneamiento básico de los campamentos (vivienda, suministro de agua, desagüe, etc.), las facilidades médicas y de bienestar al servicio del personal.

Aug 20, 1963

By L Whitbourn, K Yang, P C, E Ramanaidou

The potential of hyperspectral mineral mapping within a mine environment is demonstrated. Central to this capability has been the development of portable or vehicle-mounted, hyperspectral mine face-mapping systems. Data from these systems were used to detect subtle mineralogical variations and map their distribution across rock faces in a fashion that previously was not possible. In one study, the data usability was enhanced by ædrapingÆ the mineralogical determinations over a three-dimensional æmodelÆ of the rock-face. The eventual melding of the spectral mine face-mapping and three-dimensional spatial technologies will result in a new generation of mineralogical and structural information becoming available to mine geologists, engineers and metallurgists. Specific uses for spectrally-derived, mineral mapping data sets could include:ore grade mapping systems based on either direct detection of ore minerals themselves (eg iron and nickel oxides), or mineralogies that may be used as surrogates for ore-grade information (via various alteration minerals) after a suitable orientation survey; detecting mineralogies that have a deleterious effect on milling, metallurgical processing or have occupational health implications (talc, swelling clays, carbonates, asbestos, etc); selective mining and blending by collecting, processing and displaying such mineralogical images in near real-time to monitor ore grade and quality, and allow the separation of ore from waste during loading operations at the mine face; a mineral detection and mapping capability to assist in structural and geotechnical mine planning applications; and an enhanced geological detection and mapping capability for ore mineral species or alteration mineralogies that may be used to vector further mineralisation, update the existing mine ore model, or provide input to assist in the control of autonomous mining equipment. Within the Woodlawn open pit, Fe- and Mg-chlorites and phengitic- micas associated with sulfide mineralisation were detected and mapped. Subsequent studies using a second generation face-mapping system demonstrated the direct detection of ore-grade materials for iron-ore and nickel laterite mining activities. Satisfactory and meaningful results were extracted from data that were collected under a variety of challenging conditions. However, these non-ideal climatic and operational conditions would be expected under most operational situations in a mine environment. Development of a system using artificial illumination, permitting night-time (and eventually underground) operation and elimination of atmospheric absorption effects is underway.

Jan 1, 2006

By Herbert H. Einstein

Rock mass deformability is commonly predicted using correlations with RQD or other indices of rock mass quality, or by extrapolation from large in-situ tests. Based on the probabilistic description of rock masses empirically developed in Part I a new approach was attempted in modeling for predictions of deformability. This approach decomposes the rock mass into spatially variable joints described by probability distributions, and intact rock blocks. Stiffnesses and elastic parameters are associated with the joints and intact blocks respectively, and deformations built up by adding the contributions of each. This model allows relaxation of many of the simplistic geometric assumptions which constrain parallel attempts to model deformation in rock masses. The model has been applied to four standard cases in order to test its results against previously existing models, and to check whether it replicates empirical correlations. When joints are taken as parallel, common empirical correlations are closely approximated by the model output. However, the closeness to empirical correlation breaks down when variability of the jointing geometry is increased.

Jan 1, 1979

By D. C. McKeehan

The importance of properly bonded rail joints has received the attention of The National Research Council, whose committee will investigate several methods now used and determine the merits of each as applied to street railways. The results of this investigation should be appreciated no less by the mining industry. Literature on the subject of bonding mine tracks agrees, as a rule, "that the work is poorly done." With present day facilities there is little excuse for inadequate track conductivity, and a job well done must be maintained in order to realize results. Many years ago The Union Pacific Coal Company installed their first haulage locomotive, and at that time used the channel pin bond for joining the rails. The system utilized 500 volts and the, relatively small current for a large amount of power, undoubtedly, contributed to the success of the system. The bonding of both rails was considered imperative in those days, while now the bonding of one, rail is considered sufficient in most instances. The recent installations utilizing 250 volts and correspondingly heavier currents required a more effective method of joining the rails for use as an electrical conductor. The company has used the arc-weld bond since its introduction in 1919. The art of electric welding found great favor for various methods of doing the work. The first arc-weld bonds were placed on the outside of they ball of the rail, but the bonds were ill-adapted to rails lighter than sixty pounds per yard, and the results were that grooved locomotive wheels or derailed cars removed the bonds. Familiarity with the process of electric welding brought forth numerous schemes for joining the rails. In one, instance the rails and splice-plates were welded together and with excellent results for a short time. Track movement and vibration finally broke the welds and the method was dis¬carded. Another scheme consisted of placing a channel pin over each end of an annealed copper wire about twenty inches long. The idea was to develop some way of using short lengths of scrap wire. The pin and wire were then welded to the base of the rail. Numerous joints made in this way are still intact, but successful welds were so exceptional that the practice was abandoned. Some of these bonds were welded to the web of the rail, with the result that practically all rails broke at the weld; however, this is our only record of broken rails with arc-welded bonds. At one time a quantity of No. 2 bare iron wire wasp available and was tried as a bond and proved very satisfactory. Two or three strands twenty inches long were used and were welded to the base of the rail. The method was cheap and effective and of some merit for light rails on temporary track. The use of iron wire was criticized because it did not give a balanced circuit; that is, one having equal carrying capacity for trolley and track circuits; and I am of the opinion that this is not always necessary. The total length of bond that is in circuit is so small that it contributes very little additional resistance to the complete circuit consisting of trolley wire, rails and bonds.

Jan 1, 1923

By Allan Martin, R. A. Swalin

Diffusion rates of manganese, aluminum, titanium, and tungsten in nickel were measured at temperatures between 1100° and 1300°C. Activation energies, Q, and values of the frequency factor, Do, were calculated for each system. Values of Q were found to be within 15 pet of that for self-diffusion of nickel in agreement with present theories of diffusion. ONE of the most interesting problems in diffusion concerns factors governing the order of diffusion coefficients of various solutes in a common solvent metal at low solute concentrations. An early suggestion by Rhines and Mehl' was that diffusion coefficients might each approach that of the self-diffusion coefficient of the solvent itself. Later Thomas and Birchenall' pointed out correlations between the order of the diffusion coefficients and the freezing point depressions of the solvent by the various solutes. Other correlations have been sought. To settle this question it seems likely that much more data will be needed and, in particular, data collected at low solute concentrations. This type can be obtained by special analytical techniques as well as by use of radioactive tracers. The following study was made of diffusion of manganese, aluminum, titanium, and tungsten in a common solvent, nickel, at relatively low solute concentrations: 1—Production of alloys of nickel with manganese, aluminum, titanium. and tungsten at concentrations of the order of 1 atomic pet. 2—Use of pressure-welded diffusion couples in cylindrical form. 3—Diffusion anneals in the temperature range of 1100" to 1300°C. 4—Lathe sectioning of the diffused couples. 5—Spectrophotometric analyses of lathe turnings for the solute being studied. 6—Calculation of the diffusion coefficient for each of the solutes as a function of temperature. 7—Interpretation of results with current theories of diffusion. Experimental Work Materials—Two types of nickel were used in this research. The grade designated as Vacuum melted Mond nickel was used for all diffusion systems except the Mn-Ni system for which the Vacuum melted electrolytic nickel was used. Analyses of the two grades are given in Table I. The manganese used in making alloys was 99.9 + pet pure, aluminum 99.99 pet pure, titanium 99.9 pet pure, and tungsten of C.P. grade powder. Alloys used in this investigation were prepared by melting in vacuo or under a low pressure of argon. After melting, all heats except those of nickel-manganese were poured into a cylindrical copper mold 3 in. long and 1 in. ID. In the case of nickel-manganese, the alloys were solidified in the melting crucible. For nickel-aluminum heats alumina crucibles were used and for all other heats, zirconia crucibles.

Jan 1, 1957

By Manuel Gomez

Areal distributions for ash, total sulfur, and sulfur forms were developed for the top 12 inches, the middle section, the bottom 8 inches, and the total seam of Pittsburgh coal in southwestern Pennsylvania. The sulfur and ash exhibit an apparent high local variability. As a general rule, both the sulfur and ash show high concentrations in the top 12 inches and in the bottom 8 inches of the seam relative to the concentrations observed in the middle section of the seam. The high-low sulfur and ash concentrations in the top 12 inches of the seam are not coincident with the high-low sulfur and ash concentrations in either the middle section or the bottom 8 inches of the seam. With respect to sulfur and ash, it is suggested that the top and bottom sections of the Pittsburgh coal may reflect both a syngenetic and epigenetic origin. Present data support the belief that paleotopography controlled Pittsburgh seam deposition. Evidence is presented to show that channels were cut at various times into the semilithified sediments that buried the Pittsburgh seam. In this channeling process, portions of the Pittsburgh coal may have been eroded away. Following channel development, the lower part of the Pittsburgh sandstone filled the complex system of braided channels to produce the "want areas" encountered in present mining operations. In localized areas of the Pittsburgh seam, impingement of Pittsburgh sandstone may be responsible for the lateral displacement of the coal. Information of this type becomes important in the assessment of exploration data, in the development of a quality control system for mine output, and in mine life planning.

Jan 1, 1974

By H. T. Green, R. M. Brick

True stress-strain data on alloys of pure iron with up to 2.4 pct Al were obtained in the temperature range +100° to —185°C. Alumi-num was found to reduce yield and flow stresses of iron at low temperatures but to have little or no effect on ductility. The effects of temperature and composition on strain hardening are discussed. SEVERAL independent studies of the behavior of high purity iron binary alloys at low temperatures are now in progress in attempts to evaluate systematically the variables affecting the low temperature brittleness of ferritic steels. This paper reports the results of one such investigation in which the tensile properties of aluminum and aluminum plus silicon ferrites were measured from 100" to —192°C. True stress-natural strain data have been obtained in order to evaluate as many as possible of the parameters which describe the behavior of the materials involved. In comparable studies at the National Physical Laboratory in England, iron and iron alloys of high purity have been produced' and tested at subat-mospheric temperatures.' True stress-natural strain curves were obtained there also. The purest iron contained 0.0025 pct C and 0.001 pct O and N. Even this, as normalized at 950°C following hot rolling, showed little ductility at -196°C. The grain size was ASTM No. 3, and the room-temperature yield strength was 17,800 psi (which seems too high for pure iron). Some of the NPL irons contained considerably more oxygen and demonstrated intergran-ular fracture at —196°C. The authors2 carefully differentiated between intergranular fractures associated with excessive oxygen content and transcrys-talline cleavage with little ductility encountered at —196°C in the purer material. The cleavage stress was half again as great as that associated with inter-granular fracture. Test Material, Preparation, and Procedures Of a number of Fe-A1 alloys produced, eight were considered to be sufficiently pure for testing. Partial chemical analyses (Table I), low observed yield points, and high ductilities indicate these alloys to be comparatively pure for vacuum-melted irons of sizable ingots, 5 Ib or more. To produce the binary Fe-A1 alloys, electrolytic iron was melted in air, cast into slabs, and rolled to strips 0.010 in. thick. These strips, joined into a continuous ribbon and wound into 2 1/2 in. diameter spools, were subjected for four weeks to a moving atmosphere of purified dry hydrogen in a stainless-steel tube at 1050" to 1150°C. Charges of these spools were melted in beryllia crucibles under good vacuums (1 micron), and aluminum (99.97 pct Al) was added to the melts. Compositions of these alloys are recorded in Table I. The ingots were hot forged and then cold rolled at least 65 pct to 3/8 in. rods which were vacuum annealed to the desired grain size, approximately ASTM No. 4, prior to machining into tensile test bars. All tensile specimens had gage sections 1 in. long, with a fillet of 1.5 in. radius to the shoulder. Gage diameters were 0.250 in, except for a few rods where additional cold work required use of a 0.200 in. gage section. After machining, 0.002 in. was removed from the gage diameter using 240, 400, and 600-grit metallo-graphic papers. The final polish with 600 grit left the fine scratches running in the longitudinal direction. By this means, surface metal strained during machining was removed. A few specimens heat treated after machining were similarly reduced 0.004 in. to remove any material affected chemically by the atmosphere during heat treatments, as is discussed in a later section. Tensile tests of the eight alloys at constant temperatures from +100° to —185°C were performed in apparatus which has been described." The essentials include a double-walled insulated metal vessel which contained the liquid heat-transfer medium surrounding the test specimen. A constant temperature was maintained by means of a pyrometer which regulated the pressure of dry air driving liquid air through a copper coil. Temperature variation was less than ±2°C during a specific test. For axial straining, two lengths of case-hardened chain, terminating in simple shackles, loaded the specimen through threaded grips. The lower grip bar passed through a hole in the bottom of the test vessel to which it was joined by a thin-walled

Jan 1, 1955