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By Juliana Gonçalves Pohlmann

A redução das emissões de CO2 pela substituição parcial de carvões por um combustível renovável como a biomassa é um assunto de crescente interesse na siderurgia. As emissões de CO2 na etapa de redução podem ser reduzidas pelo uso de biomassa como combustível ou pela queima em condições de oxi-combustão. Este trabalho visa investigar a combustibilidade de eucaliptos termicamente tratados em laboratório em atmosferas convencional (O2/N2) e de oxi-combustão (O2/CO2), comparando com uma moinha de carvão vegetal e carvões típicos do processo de injeção em altos-fornos (PCI). Os testes de combustibilidade foram conduzidos em um forno de queda livre (DTF) a 1.300°C com diferentes proporções de O2/N2 e O2/CO2. Os chars do DTF foram caracterizados quanto à aparência ao microscópio, área superficial e reatividade. Os eucaliptos termicamente tratados apresentaram as maiores combustibilidades, seguidos pela moinha e pelos carvões. Os chars das biomassas apresentaram estruturas mais reativas do que os chars dos carvões, e maiores áreas superficiais e reatividades. As poucas diferenças de combustibilidade e reatividade devido à atmosfera de oxi-combustão indicaram que, se aplicada ao alto-forno, esta tecnologia pode não ocasionar efeitos negativos no comportamento de carvões e biomassas.

Aug 16, 2017

Arizona ROBERT W. THOMAS, Chairman 'ROBERT W. HUGHES, Vice-Chairman HUBERT O. WOODS, Secretary-Treasurer American Smelting & Refining Co., Hayden, Ariz. FRANK A, WARDLAW, JR., National Director THOMAS C. CHAPMAN P. D. I. HONEYMAN CARL H. COLE JOHN E. LANNING. JOHN H. DAVIS JOHN C. LOVING EDW. G. DENTZER ALBERT MENDELSOHN MORRIS G. FOWLER BRENT N. RICKARD H. C. HENRIECHARLES F. WILLIS Black Hills BANCROFT GORE, Chairman N. P. GOODRICH, First Vice-Chairman C. N. KRAVIG, Second Vice-Chairman C E. SCHMIDT,

Jan 1, 1941

By N. B. Gray, R. V. Culver, W. S. Boundy, N. W. Stump

The kinetics of sulfation of single crystals of lead sulfide to lead sulfate have been studied between 969" and 1073°K in gas atmospheres of known composition using a thermobalance technique. The data are described by an equation derived on the basis that diffusion outward through the Product layer is the major controlling step. The rate of sulfation is linearly related to the logarithm of the sulfur trioxide partial DESPITE its industrial significance the oxidation of lead sulfide has received limited attention. The oxidation reactions have been studied using beds, briquettes, single crystals, or thin films of lead sulfide. Lead oxide and lead sulfate (PbSO,) were formed when Mclntoshl and Gardner2 roasted beds of galena pressure and the temperature coefficient of reaction is 40 ± 5 kcal per g mole. Gold marker experiments show that the sulfate layer grows by outward movement of ions through the sulfate layer. Initially the PbSO, adheres to the PbS but later forms an irnpewious spheroidal envelope; PbS vaporizes and pb2' ions diffuse through the envelope to react at the external surface. in air at temperatures up to 800°C. In a more extensive investigation, Tchizhykov3 obtained Pb, PbO, and PbS04 in accordance with Eqs. [1] to [4], when a bed of -200 mesh galena was oxidized in O2-N2 mixtures at 700° to 900°C.

Jan 1, 1968

By Elisa Araujo Santos Darsie

A busca na melhoria da qualidade dos aços, principalmente no caso de aços limpos, fez com que o distribuidor de lingotamento continuo também seja empregado para a remoção das inclusões responsáveis por prejudicar as propriedades mecânicas dos aços. Uma melhor eficiência desta função do distribuidor pode ser atingida com o conhecimento das características do escoamento do banho metálico de modo que se possam propor modificações na configuração do distribuidor. Esses fenômenos de escoamento e remoção de inclusões podem ser simulados mediante a utilização da modelagem física. O objetivo deste trabalho é avaliar quatro configurações internas de distribuidor por meio da qualificação do escoamento via ensaio de linhas de fluxo e quantificação de inclusões passantes pelo veio com o ensaio de remoção de inclusões. As variáveis de controle utilizadas neste estudo são: velocidade de lingotamento, presença de barreiras e presença de tubo longo. Os resultados apresentados para o distribuidor em questão mostram que para os casos com o tubo longo, o uso da barreira torna o escoamento predominantemente ascendente eliminando o curto-circuito e favorável a remoção de inclusões passando de 29,76 para 24,29% de inclusões passantes pelo veio. Enquanto que para os casos sem tubo longo, o uso da barreira proposta diminuiu o contato do aço com a escória sobrenadante, aumentou o curto-circuito e aumentou também o percentual de inclusões passantes pelo veio de 2,56 para 3,01%.

Aug 8, 2018

By V. J. Parks, Leonard Obert, A. J. Durelli

The state of stress in the region where core discing initiates has been investigated through the use of three-dimensional photoelastic models and the results of this study have been compared with those of a previous investigation of rock models. This comparison showed that discing initiates at a point of maximum shear stress, but that the magnitude of the shear stress, as determined photoelastically, is much larger than the shear strength of the rock as deter-mined from conventional triaxial testing. Moreover the shear stress required to produce discing is not constant, but depends on the applied stress field. Possible explanations for these effects are included in this article. In both exploration core drilling and overcore drilling to determine the stress in rock, occasional sections of the core obtained are broken into a series of discs.I* This discing phenomenon has been investigated in the laboratory to ascertain the state of stress required to produce it. The objective of the study was to obtain information that would make it possible to approximate the state of stress in subsurface rock from which disced cores are obtained. Referred to as the discing test, this laboratory study was conducted to determine the applied axial and radial loads required to produce discing in cylinders of rock from several sources. The dimensions of these cylinders are given in Fig. 1. Discing was produced by first applying an axial load to the cylinder and then diamond drilling the core along its axis. The radial load was then incrementally increased until discing initiated. The discs fractured or ruptured* on surfaces approximately normal to the axis of the core (planes A, B, C, D, E, Fig. 2). In many instances, the bottommost disc fractured before the drill had advanced past the points F and F', cre- ating a mush room-shaped fracture surface FEF'. Alternatively, it was also found that the same shaped fracture surface could be created by first drilling in an unloaded core to some point, say F and F', and then triaxially loading the core until fracture occurred on the plane FEF'. Jaeger and cook4 produced similar fracture surfaces in specimens subjected only to a radial biaxial load. From these laboratory studies and observations made in the field, it can be inferred that fracture or rupture initiates in the proximity of the lowest point in the kerf area, (at F and F', Fig. 2) and that the fracture or rupture surface progresses inward from this point. The experiments described above, however, do not provide any information as to the state of stress at the point at which fracture or rupture initiates. In the investigation discussed in the following sections, a three-dimensional photoelastic analysis was conducted to determine the stress distribution in the proximity of the kerf area of a triaxially loaded plastic (epoxy) cylinder containing a short section of core.

Jan 1, 1969

By V. B. Achanti, A. W. Khair

Laboratory studies were carried out at West Virginia University to investigate the rock fragmentation mechanism by continuous miners using an automated rotary cutting simulator. The primary factors influencing the fragmentation process were found to be: bit spacing, bit geometry, depth of cut and cutting drum rotational speed. This paper presents the influence of these parameters in achieving optimum energy consumption and minimizing dust generation during rock fragmentation process. Tree bits were used simultaneously on Indiana limestone while the bit tip angle was varied from 60° to 900. Bit spacing was varied from 2.54 cm (1 in.) to 5.08 cm (2 in.) while the cutting process was assessed for varying cutting depths. Restorable dust generated during the course of the experiments was analyzed utilizing cascade impactors. Assessment of these parameters has led to a better understanding of the cutting mechanism by continuous miners in terms of energy consumption and dust generation.

Feb 24, 1997

By Torrico Mesa

El presente artículo describe la etimología, historia, posición, superficie, límites, división política, población, geología y los asientos minerales de la provincia de Cajatambo, Junín. Entre los principales asientos están: Chanca, Raura, Quichas, Izguez, Pomahuín, Auquimarca, Santa Rosa, Rosario e Irismachay. Asimismo, se describen los yacimientos mineros, amalgamación, lixiviación por prodecimiento, metalurgia, fundición y las oficinas metalúrgicas.

May 1, 1956

The term geochemistry - chcmbtry' of the earth - is almost limitless in its implied subject, but of recent years a major trend of research in this field has been towards economic application in the search for mineral deposits, and in particular for those of some ofthe less common elements for which a demand now exists.Geochemistry is in a state of slow transition from a purely descriptive subject to a fundamental science concerned with the relationships that exist between the distribution of the elements in the earth's crust and the physical characteristics of the atoms of those elements. The progress achieved promises a set of basic principles which will relate the atomic characteristics of an element to the physico-chemical conditions that make for its dispersion or concentration. This means that, given a geological map of an areasufficiently detailed for the physico-chemical conditions existing in past geological eras to be deduced, there is the possibility that the relative distribution throughout that area of any element present, and its likely mode of occurrence, could be predicted from a consideration of its atomic characteristics.Since the atomic characteristics of the elements are becoming increasingly well defined by physical research, the attainment of this ideal of prediction depends upon:(a) the strengthening of geochemical theory; and(b) the development of petrological and mineralogical methods of assessing the conditions of temperature and pressure prevailing in geological formations at various stages in their history.The other prime requirement is a d.etailed geological map - a requirement that is all too often lacking.The fact that there has been very little "geochemical approach" to problems of economic geology in Australia should not be taken to mean that there is little point in trying to develop such an approach here in as active and as rigidly scientific a manner as possible. The degree of success that has attended the attempts so far made, to which reference is made below, suggests the reverse, particularly in view of the relatively slight cost involved if the investigations were properly organised on a centralised basis. There are three aspects of geochemistry that are directly applicable to the search for economic minerals.(a) The classic technique of the prospector can be made more sensitive and reliable by the use of modern equipment coupled with the application of geochemical theory to geological and structural data. The case of the rare alkali elements (see below) is givenhere as an illustration of the way in which the distribution of elements can be predicted from the first principles of geochemistry, thereby replacing the prospector's dependence on his "sixth sense" that enabled him to suggest that a certain area of formation was"favourable" for the occurrence of a certain type of mineral deposit.At its best, this sixth sense amounted to an almost subconscious correlation of all relevant associations and typical occurrences of the particular mineral experienced by the prospector during his...

Jan 1, 1950

By A. Ghosh

Commonly used predictors of ground vibration from blasting, being linear in log-log plot, do not model the underlying physics of wave attenuation. Amplitude of the wave decays with distance due to geometrical spreading and inelastic attenuation producing a nonlinear carve in log-log scale. The nolinear decay of seismic waves has also been observed from non-explosive sources, such as, pile driving, drop hammer, traffic, etc. The improved predictors, by explicitly taking these two mechanisms into consideration, model the data trend extremely well at all distance ranges. Actual field data from different studies have been used to validate the improved models.

Jan 1, 1991

By David Newman

Multiple seam underground coal mining is ubiquitous in Appalachia. Many coal properties have from two to ten or more economically mineable coal seams. Because of the ability to penetrate 600-feet to 1,000-feet or deeper into the mountainside leaving panels of web pillars separated by barrier pillars, highwall mining is a hybrid between surface and underground mining. As a result, many of the ground control problems commonly associated with multiple seam underground mining exist with multiple seam highwall mining. These include: i) superjacent mines, subsidence and caving propagating to overlying seams and ii) mines, pooled water and the potential for inundation resulting from a iii) breakthrough between an active highwall mine and abandoned underground mines in the same or superjacent seams, the presence of overlying or underlying mine workings where iv) pillar columnization in the active mine is not possible, and v) the question of whether to mine ?top-down? or ?bottom-up.? Case histories are presented from southeast Ohio where the Middle Kittanning No. 6 and Lower Kittanning No. 5 seams are successfully highwall mined with 20-feet to 40-feet of largely shale interburden. A highwall miner was caught in a highwall collapse in the Middle Kittanning No. 6 seam when it was overmining auger workings in the Lower Kittanning No. 5 seam. Multiple seam interaction caused by the overmining transferred overburden stress onto the Lower Kittanning No. 5 seam. The overburden concentrated through web pillars initiated auger web pillar failure, resulting in roof collapse and subsidence in the Lower Kittanning No. 5 seam that propagated up to the Middle Kittanning No. 6 seam. A second case history involves multiple seam highwall mining in southeast Kentucky. The A3 Rider, A3, B2, and C1 seams are being highwall mined around abandoned underground mines in the A3 and B2 seams and augering in the A3 Rider. Because of spoil storage constraints for the surface contour mines, the highwall miner follows the active pits in each seam so a standard sequence of ?top-down? or ?bottom-up mining does not exist. The planning and engineering design considerations associated with each case history is presented along with geotechnical information. In the case of the highwall collapse a back analysis is presented of the stability and safety factors for the auger webs, highwall miner web pillars, and barrier pillars.

Jan 1, 2009

By J. H. Mallery, J. H. Keeler

THE crystal structure of Zral, the compound richest in zirconium (91.03 pct Zr by weight) in the system Zr-Al, has been found to be ordered face-centered-cubic. This compound is of particular interest, since it is encountered as the precipitated phase in potentially useful zirconium-rich alloys. It forms peritectoidally from body-centered-cubic zirconium and Zr,Al at about 975°C. The Zr-A1 constitution diagram has been reported by McPherson and Hansen.' For the primary determination a 100 g ingot was prepared by arc-melting in a water-cooled copper crucible under purified argon. The raw materials were crystal-bar zirconium (a purity of better than 99.7 pct) and spectroscopically pure aluminum. The ingot was double melted, examined metallographi-cally, and found to be quite uniform as shown in Fig. 1. The hardness of the as-cast button was VHN 390 to 445. A 20 mil diam specimen was prepared from annealed (900°C) filings of Zr,Al. The specimen was mounted in a 5 cm radius powder camera and an 8 hr exposure was taken using copper radiation with a nickel filter. The structure of the compound Zral was found to be ordered face-centered-cubic of the Cuau type, with an a,, value of 4.37220.003A. Its calculated density is 5.976e0.013 g per cu cm. The relative intensities for the lines were calculated using the formula 1+cos2 20 I oc----------------- • p • /F7 sin2 0 cos 0 1 + COS' 20 where----------------is the Lorentz polarization fac- sin2 0 cos 0 tor, p is the multiplicity factor, and F is the structure factor. The X-ray data are given in Table I. The compound has exhibited plasticity when present as particles in a matrix of a zirconium. During hot working at about 900°C, the compound has been found to deform plastically to the extent that some of the particles exhibit a length-to-width ratio greater than 4:1 as shown in Fig. 2. In answer to the discussion of ref. 1, McPherson and Hansen pointed out that the compound may be cold rolled and reduced as much as 33 pct. Zr,Al has also been found2 under certain conditions to precipitate in lamellar form at grain boundaries of the a phase of hexagonal-close-packed zirconium. Acknowledgment This work was carried out under Contract W-31-109-Eng 52 for the United States Atomic Energy Commission.

Jan 1, 1956

By James R. Hein

Rodriguez Seamount, located 150 km off the central California coast at the base of the continental slope, was studied using the ROV Tiburon aboard MBARI?s R/V Western Flyer, October 13-16, 2003. Fe-Mn crust and rock samples were collected along the SW flank of the seamount at water depths from 700 to 2100 m; bottom-water dissolved oxygen content (O2) and temperature were determined at each sample site. Fifty-three samples of bulk crusts, crust layers, and surface scrapes (~0.5 mm) were analyzed for 59 elements. Data allow for the correlation of crust compositions with precisely known water depths and seawater O2 measured at the actual site of sample collection. This is the first detailed study of Fe-Mn crust compositions in a region of strong continental-margin upwelling. Compared to open-ocean seamount Fe-Mn crusts, Rodriguez crusts have significantly higher (2-6 fold) mean concentrations of Fe (26.9%), Al (1.65%), Si (13.0%), Cr (82 ppm), Th (64 ppm), and Ag (1.7 ppm); and significantly lower (2-8 fold) mean concentrations of Ca, P, Bi, Co, Cu, Ni, Tl, and especially Te (8.2 times lower). All but one Fe/Mn ratio are >1 compared to <1 ratios for open-ocean crusts. O2 contents (0.35-2.03 ml/L) are nearly perfectly corrected with water depth and elements correlated with one are correlated with the other. The Fe-Mn surface scrapes represent 60-450 ka (mean 150 ka) of growth, whereas the dissolved oxygen contents of seawater represent an instant in time. Assuming that the entire sample set was affected uniformly by oceanographic changes, we suggest that correlation of elements with O2 may reflect oceanographic processes. O2 has a negative correlation with P, V, As, Fe, U, Be, Pb, Cr, Mg, Y, Bi, Te, and REEs (except Ce) and a positive correlation with aluminosilicate-hosted elements (Al, K, Rb, Cs). This later relationship is related solely to water depth, indicating that detritus shed down the seamount slopes accumulates in greater abundances in deeper-water crusts. Si/Al ratios indicate that the detritus includes a large component of biosilica produced by upwelling-mediated high productivity. These observations are supported by positive correlations of aluminosilicate-hosted elements with crust growth rates (range 1.2-13.0 mm/Myr). In contrast, other elements (Sr, Co, Mn, Mg, Te, As, Mo, V, W, U, Ti, Ni, REEs, etc.) are negatively correlated with growth rates. Growth rate has a weak positive correlation with O2. These compositional characteristics indicate that even though low-O2 seawater acts as a reservoir for Mn and associated elements and produces slow growth rates, which would allow for the concentration of elements and surface oxidation processes to occur, the high rate of input of detritus and high bioproductivity ameliorate the strong concentration of most metals. This dilution is significantly enhanced by the doubling of FeOOH in the crusts--the main cause of the generally high growth rates compared to open-ocean crusts. The high growth rates limit the oxidation of Co, Tl, and especially Te on the crust surface, which is reflected by their relatively low concentrations. Within the range of oxygen contents measured, O2 has less of an influence on crust chemistry than does the availability and incorporation of FeOOH and detritus.

Jan 1, 2004

By Jiwei Duan

The energy transferred from a hammer to the pile top is considered as the effective energy in this paper. The effective energy is related to the pile dimensions, soil and pile-soil interface properties. This relation may be expressed as an equation based on the dimensionless theory. The relationship between pile capacity and effective energy was studied by performing a series of wave equation analyses using a commercial software called GRLWEAP (Wave Equation Analysis Program) by GRL Engineers, Inc. The results show that the pile capacity increases with the blow count when the effective energy is constant, however, it has a little change as the blow count is over 100 blows per foot. The pile capacity decreases as the ratio of pile penetration depth to pile diameter increases if the effective energy is constant. The pile capacity will increase as the pile diameter and wall thickness increases if the effective energy is constant. The pile stickout (pile length above the ground surface) does not have a significant effect on the effective energy and may be neglected. Curves for pile capacity versus effective energy are presented to be used for preliminary hammer selection according to effective energy and hammer efficiency. Finally, a case from PDA testing was studied. Measurements of the effective energy and pile capacity by CAPWAP were presented and compared with the results by GRLWEAP.

Jan 1, 2006

By N. R. Allen, J. D. Steenkamp

Oxidative roasting is applied on an industrial scale to beneficiate ilmenite concentrates from South African East Coast heavy minerals deposits - the aim is to increase the magnetic susceptibility of ilmenite to allow magnetic separation from chromite. The intention of this paper is to give researchers new to the field an overview of the beneficiation of ilmenite through roasting and magnetic separation, touching on the relevant fundamental aspects of magnetism.

Jan 1, 2005

By A G. Tomkins

"Approximately 32 per cent of the worldÆs total gold production has come from greenstone belts (Frimmel, 2008). In these regions numerous small to large, quartz vein-associated gold deposits are hosted in metamorphic rocks ranging from lower greenschist to granulite facies. Historical exploration has focused its efforts on rocks of greenschist to lower amphibolite facies because these seem to contain the most deposits. Consequently, these regions are now reaching mature brownfield status, particularly in developed nations, and finding new deposits is becoming progressively more difficult. In comparison, regions of similar tectonic setting, but instead containing high-grade metamorphic rocks of mid-amphibolite to granulite facies, have received little attention because the first explorers found fewer deposits there.However, these regions certainly do contain some very significant gold deposits such as Hemlo in Canada (~684 t Au), Renco in Zimbabwe (~31 t Au mined since 1980), the very profitable Challenger deposit in South Australia (~36 t Au; recovered + reserve + resource), and the most recently discovered Tropicana deposit in Western Australia (~182 t Au; reserve + resource). High-grade metamorphic terrains therefore offer explorationists an excellent opportunity to move onto relatively green fields within developed nations, which carry less risk associated with development. However, explorationists have comparatively little knowledge of the geological controls on gold distribution in high-grade terranes because: industry experience lies in traditional lode-style gold deposits these gold deposits are geologically more complex there has simply been minimal research conducted on these deposits as a holistic group.Furthermore, research conducted in the last five years has shown us that the previous widely accepted model for gold genesis in these terranes, the crustal continuum model, is incorrect. Here, I discuss features from several gold deposits hosted in high-grade metamorphic rocks and use these to define two categories for explorationists to consider: deposits that formed prior to peak metamorphism (metamorphosed gold deposits) deposits that formed well after peak metamorphism (post-metamorphic gold deposits). There are none that have been convincingly shown to have formed during peak metamorphism.CITATION:Tomkins, A G, 2013. Gold deposits in highly metamorphosed terranes, in Proceedings World Gold 2013, pp 23-26 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 26, 2013

This Bureau of Mines report and its companion report (Information Circular 9143) have been prepared to assist in the preparation of prefeasibility type estimates for capital and operating costs of mining of various types of mineral occurrences using current technology. The handbook provides a convenient costing procedure based on the summation of the casts for the unit processes required in any particular mining or mineral processing operation. The costing handbook consists of a series of costing sections, each corresponding to a specific mining unit process. Contained within each section is the methodology to estimate either the capital or operating cost for that unit process. The unit process sections may be used to generate, in January 1984 dollars, costs through the use of either costing curves or formulae representing the prevailing technology. Coverage for surface mining includes dredging, quarrying, strip mining, and open pit mining. The underground mining includes individual development sections for drifting, raising, shaft sinking, stope development, various mining methods, underground mine haulage, general plant, and underground mine administrative cost. This system can be used for estimating cost data for an undeveloped deposit or for checking or verifying mining costs from a developed deposit, with a minimum amount of background information.

Jan 1, 1987

By Pol Duwez

IN the course of an investigation of the V-CO system, two intermediate phases were found. One of these phases corresponds approximately to the stoichiometric composition VCo and is isomorphous with the sigma phase in the Fe-Cr system.&apos; The second phase has the composition V3Co; its crystal structure is described in the present note. The alloys were prepared by mixing the two metals in the powder form, pressing a small disk weighing about 5 g at 80,000 psi, and arc melting this disk on a water-cooled copper plate in an atmosphere of pure helium. The details of this technique have been described.&apos; The vanadium powder was obtained from Westinghouse Electric Corp., Bloomfield, N. J. This powder is probably of very high purity, since when it is properly sintered or melted in the above-mentioned arc furnace, ductile specimens are obtained. The cobalt powder, from Charles Hardy, Inc., New York, contained 0.5 pct Ni, 0.1 pct Cr, and traces of Si and Fe. After melting, the V,Co samples were sealed in evacuated quartz tubes and homogenized for ten days at 800°C. Powder diffraction patterns were obtained with a 14.32 cm diam camera, using Ka copper radiation. The patterns were readily indexed on the basis of a primitive cubic lattice with a parameter equal to 4.675A. The density, determined by the immersion method, was 6.71 g per cu cm; hence the number of molecules per unit cell is approximately 1.95; i.e., 2. At this point, the possibility that the structure might be that of beta tungstena became apparent. The beta tungsten structure is described as follows: Space group 03,, — Pm3n 2 Co in (a) : 000; ?4lhYZ (hhl) reflection present only if 1 = 2n. Assuming this structure to be the correct one, intensities were computed by means of the usual eauation: 1 + cos220 I oc p F sin 0 cos 6 where F is the structure factor, 0 the Bragg angle, and p the multiplicity factor. The observed and calculated values of sin 0 and the intensities are given in Table I. The agreement between the observed and the calculated sin 0 is good and there are no flagrant discrepancies between the calculated intensities and those estimated visually. The (hhl) reflections for which 1 is odd are not observed, as required by the space group. In addition, the (410), (430), and (531) reflections are missing as expected, because of the special (a) and (c) positions in0%. However, six reflections—(llo), (220), (310), (411), (422), and (510)—which have very weak computed intensities were not observed. For these reflections, the structure factor is proportional to the difference between the scattering factors of the two atoms in the structure. Since the scattering factors of vanadium and cobalt are not very different, these reflections are weak. However, by using Ka chromium radiation, whose wavelength is just above the absorption edge of vanadium, the effective scattering factor of vanadium may be decreased by one or two units; consequently the difference between the cobalt and vanadium scattering factors is increased. It was, indeed, found that in a powder pattern taken with chromium Ka radiation, the three reflections (110), (220), and (310) were actually present. The three other reflections (411), (422), and (510), with spacings smaller than half the wavelength of chromium Ka, were obviously not obtainable with chromium radiation. All the experimental results appear to confirm the beta tungsten structure for V,Co. In this structure, each cobalt atom is surrounded by twelve vanadium atoms at 2.61A; each vanadium atom is surrounded by two vanadium atoms at 2.34A, four cobalt atoms at 2.61 A, and eight vanadium atoms at 2.86A. Acknowledgment This work was done at the Jet Propulsion Laboratory, California Institute of Technology, under contract number W-04-200-ORD-455 with the Army Ordnance Department, Washington, D. C. The author wishes to thank this agency for the permission to publish the results of this investigation. References &apos;P. Duwez and S. R. Baen: X-Ray Study of the Sigma Phase in Various Alloy Systems. Symposium on the Nature, Occurrence, and Effect of Sigma Phase. ASTM Special Tech. Pub. No. 110, pp. 48-54. Philadelphia, 1951. 2 C. H. Schramm, P. Gordon, and A. R. Kaufmann: The Alloy Systems Uranium-Tungsten, Uranium-Tantalum, and Tungsten-Tantalum. Trans. AIME (1950) 188, pp. 195-204; Journal of Metals (January 1950). 3 M. C. Neuburger: The Crystal Structure and Lattice Constants of Alpha and Beta Tungsten. Ztsch. fiir Krist. (1933) 85, pp. 232-237.

Jan 1, 1952

By James W. Cameron

DESPITE the fact that, after oxygen and silicon, aluminum is the most abundant and widely distributed element in the earth&apos;s crust, it is, commercially, a modern metal. Attempts were made by Sir Humphrey Davy and other chemists to decompose alumina, the oxide, into its elements, but with unsatisfactory results, and it was not until 1827 that Wohler succeeded for the first time in isolating the metal in pure form. Some thirty years later, commercial production of aluminum was started in a plant near Alais, France, using a process developed by Deville which was a modification of that of Wohler. It was not, however, until around 1886 that possibilities of low-cost production were realized. Hall and Heroult discovered, independently, the now famous process for extraction of aluminum by the electrolysis of alumina (Al,O,) dissolved in fused cryolite. This discovery, with its subsequent effect in reducing the price of the metal, was perhaps the greatest single factor contributing to the remarkable growth of the aluminum industry. But only in the years following the Great War did aluminum begin to attain equal importance in many fields with other non-ferrous metals. Numerous factors, political and economic, in the past decade have had a profound effect on the industrial history of the metal. At present, systematic substitution of aluminum for other base-metals is proceeding at a rapid rate in such countries as Germany and Italy with a view towards &apos;economic self-sufficiency&apos;. Quite naturally, ?the economic depression started extensive research and experiment in various industries in an attempt to improve efficiencies and lower costs. Partial answers have been found in the extended use of aluminum and its alloys. Even against the background of tremendous technological advance that has marked the past fifty years, the rise of the aluminum industry must necessarily stand out conspicuously.

Jan 1, 1939

By Geology Staff, C. H. Stockwell

"The Flin Flon base metal mine, owned and operated by the Hudson Bay Mining and Smelting Company, is on the Manitoba-Saskatchewan interprovincial boundary at a point 400 miles north of the International boundary. The deposit was discovered in 1914 by Thomas Creighton and the Mosher and Dion brothers. Since production commenced in 1930, 25,000,000 tons of ore have been mined. On January 1st, 1946, reserves were estimated to be 26,000,000 tons, averaging 2.99 per cent copper, 4.i4 per cent zinc, and 0.089 oz. gold and 1.25 oz. silver per ton. In addition to the four metals named, others recovered from the ore include- cadmium, selenium, and tellurium. The mine workings extend to the 3,750-foot level, but little development work has yet been carried on below 3,250 feet.The known ore occurs in six lenticular to irregular bodies within a zone 500 feet wide. These bodies average 900 feet long, 70 feet wide, 1,500 feet in vertical depth, and 2,500 feet in length along the plunge. They were formed by replacement of the country rock and include ore of two types, solid sulphides and disseminated sulphides. Seventy per cent of the total known ore is of the solid sulphide type. This consists essentially of metallic sulphides- chiefly pyrite- with included remnants of the host rock, and additional quartz and carbonate. In places, the ore exhibits banding, inherited from pre-existing structures. The disseminated ore occurs usually on the footwall side, and along the bottom of the plunge, of the solid sulphide bodies."

Jan 1, 1954

By J. J. Mather

NEPHELINE SYENITE is a feldspathic rock resembling granite in texture and hardness but it is white in colour and contains appreciable quantities of the mineral nepheline, the result of a silica deficiency. It is relatively common, with known occurrences in Russia, Scandinavia, India, Canada, United States, and other parts of the world. However, the particular deposit being mined at Nephton, Ontario, by American Nepheline Limited is unique in its remarkable uniformity and low content of iron bearing minerals, both qualities essential in a ceramic raw material. The orebody is a pear-shaped mass over five miles in length, up to a mile in width, rising in three prominent ridges as much as 300 feet above the surrounding lakestudded terrain. American Nepheline holdings, consisting of 2,200 acres, comprise some 85 per cent of the total mass.

Jan 1, 1957