Search Documents

By A. J. Hatch

Recent disclosures concerning strengthening of anisotropic sheet materials under biaxial stresses are reviewed. This biaxial strengthening has been termed "texture hardening" by Backofen and is related to the normal anisotropy parameter, R. Measurements of R made on three annealed titanium alloys indicate a Ti-4Al alloy will have the greatest potential for texture hardening, followed in order by Ti-5Al-2.5Sn and Ti-6Al-4V. Relative to sheet texture, a review of the deformation mechanisms in titanium alloys would indicate that a preferred orientation for "texture hardening" is where the (0001) pole is normal to the sheet plane. This was confirmed by determination oj (0001) pole figures for the above three alloys. High R values are related to pole figures with (0001) normal to the sheet plane, whereas low R values are related to pole figures with (0001) split in the transverse direction from the sheet normal. PUBLISHED work by Backofen et al. 1 and Hosford and Backofen2 based on hill's' mathematical theory of yielding in anisotropic metals has indicated that significant strength advantages under biaxial stresses are possible in hcp alloys, provided an ideal (0001) [1010] sheet texture exists. This tendency to strengthen under biaxial stresses has been termed "texture hardening".1 It can be quantita- tively characterized by a strain-ratio parameter, R, where R may be determined from the ratio of natural width strain to natural thickness strain as measured on a uniaxial test specimen cut parallel to the rolling direction. If R is greater than 1.0, then strengthening under biaxial tension would be predicted. Considering the a titanium alloys which have an hcp crystal structure, Williams and Eppelsheimer4 have reported that commercial-purity grades deviate from the ideal (0001) sheet texture mainly in an approximate 30-deg rotation of the basal plane, toward the transverse sheet direction. However, McHargue et a1.5 have shown that the angle of rotation of the basal plane is sensitive to alloy content. In particular, a titanium alloy with 3.8 pct Al was reported to have the ideal (0001) [1010] texture after cold rolling. Additionally, Backofen et a1.1 using plane-strain compression tests have reported R values greater than 5.0 for the commercial 0 alloy Ti-5A1-2.Sn (110-AT). In view of these findings, a program was initiated to further determine the potential of commercial Ti-5A1-2.5Sn and an experimental Ti-4A1 alloy with respect to "texture hardening". Also, because of its wide commercial use, Ti-6A1-4V was included in the investigation. BIAXIAL-STRESS THEORY FOR ANISOTROPIC MATERIALS Backofen ef al.,1 based on the mathematical theory of Hi11,3 has introduced the concept of "texture hardening". In this work, it was shown that possi-

Jan 1, 1965

By R. J. Reynik

A semiempirial small flunctation theory of diff- sion in liquids is presented, which employs a fluctuation energy assumed quadratic for a small atomic or molecular displacement and Einstein's random-iralh model. The resulting diffusion equation is given by In these equations. D is the diffusivity, is the average liquid shite coordination number (at interatomic distance d. cm. T is the absolute temperature, xu. em, is (the diffusive displacement. K, is the quadratic fluctuation energy force constant, and rg, cm, are the radii oj diffusing atoms A and B, respectively. The quantities Xn and K are calculated from the computer-filled values of the slope and intercept. respectively. The radius of self-diffusing atom or radii and of diffusing atoms A and B are eta United and compared with values reported in the literature.. The predicted linear variation of diffusivity with. It tempera lure htm been observed in approximately thirty-iire metallic liquid systems, and in over seventy-fiee other liquid systems, including the organic .alcohols, liquified inert gases, and the molten salts, ALTHOUGH the average density within a macroscopic volume element of liquid is constant for fixed total number of atoms. pressure. and temperature, there exist microscopic: density fluctuations within the respective volume element. As such the microscopic volume available to an atom and its Z first nearest neighbors at any instant of time fluctuates above and below the average volume available to these atoms. If one assumes that liquid state atoms vibrate as in a solid. and further postulates that the mean position of any atom in the liquid state is not stationary. but shifts during every .vibration a distance 0 5 j 5 xo. then every atom in the liquid state continuously undergoes diffusive displacements which vary in the range 0 5 j 5 ro. Mathematically. for a binary liquid system consisting of atcrms A and B. the maximum diffusive displacement. .YO, is defined by the equation: where d is the average liquid state interatomic distance at specified liquid state coordination number Z. and v~ \ and vg are the effective radii of diffusing atoms A and B: respectively. For self-diffusion. r^ equals rg , and Eq. [I.] reduces to: It is interesting to note that Eq. [l] or [2] can be used to compute the radii of the diffusing atoms, provided one had an experimental evaluation of xo. As such. the computed radii could be compared with metallic or crystallographic ionic radii to ascerlain the electronic character of the diffusing atoms. Thus it is proposed that in the liquid state the n~otion of an atom relative to its original equilibrium position of oscillation represents the thermal vibration of any atom and its Z first nearest neighbors. while the small and variable displacements. 0 5 1 5 xc,. of the centers of oscillation represent the complex diffusive motions of the atoms at constant temperature and pressure. This is consistent with data obtained from slow neutron scattering by liquids1 ' and resembles an itinerant oscillator model of the liquid state.'" It is further postulated that the atomic displacements characterizing the liquid state diffusion process are essentially a random-walk process. As such. it nlay be described by Einstein's equation:' where D is the diffusivity. sq cm sec-'. j2 is the mean square value of the diffusive displacement. and i> is the frequency of density fluctuations giving rise to diffusion. FORMULATION OF DIFFUSION EQUATION The effective spherical volume occupied by an atom, as a consequence of a microscopic density fluctuation which enlarges the volume available to any atom, exceeds its average liquid state atomic volume by an amount: where AV is the enlarged spherical volume, v is the radius of the diffusing atom. and j is the elementary displacement distance from the original center of oscillation of the vibrating atom to a new center of oscillation position. For small atomic displacements. where c is a constant whose value depends upon the assumed geometry of the enlarged volume. For a spherical increase in volume, c equals 4nr2. Following the treatment of Furthl' and ~walin." assuming the enlarged volu~nes AL7 for the diffusing atoms are distributed in a continuunl. the probability of finding a fluctuation in the size range 0 5 j 5 xo defined by Where c includes the geometric constant cl and Eij) is the fluctuation energy causing the volume change. But the proposed model assumes all the Z first nearest-neighbor atoms are centers of oscillation. and hence the probability that any of these atoms is adjacent to a fluctuation of magnitude 05j5xo is unity. Thus:

Jan 1, 1970

By Gustavo Henrique Bolognesi Donato

O projeto e a operação de estruturas que podem vir a conter trincas demandam estudos de integridade estrutural suportados por propriedades mecânicas à fadiga e à fratura advindas de ensaios experimentais (p. ex.: curvas J-R ou da/dN vs. ?K), sendo tais experimentos altamente dependentes da medição instantânea do tamanho da trinca. Essa medição em muitos casos é realizada com base na variação da flexibilidade com o crescimento do defeito. O objetivo do presente trabalho é validar experimentalmente soluções numéricas recentes de flexibilidade elástica que descrevem o tamanho instantâneo de uma trinca em corpos de prova de geometria C(T) e SE(B) incorporando efeitos tridimensionais. Ainda, objetiva comparar tais soluções com as disponíveis nas normas ASTM vigentes. Corpos de prova C(T) e SE(B) foram usinados conforme as referidas normas e testados em máquina universal de ensaios MTS 810.25. Na sequência, os dados obtidos foram convertidos em valores de flexibilidade normalizada (µ), determinando-se o tamanho de trinca (a) esperado com base nos referidos equacionamentos. As previsões de tamanho de trinca geradas foram comparadas com medições reais da profundidade de trinca obtidas de fractografias das amostras após separação final. No geral, tanto as soluções da ASTM como de Moreira (2014) foram consideradas acuradas e com erros máximos abaixo de ~ ±1,5%. No entanto, os resultados mostram equivalente aderência experimental das soluções disponíveis nas normas ASTM com as de Moreira (2014) para amostras C(T), mas melhor desempenho das propostas de Moreira para amostras SE(B) de variadas geometrias e profundidades de defeitos.

Aug 17, 2017

Abbey, Robert Graham, District Mgr.. The W. W. Sly Mfg. Co., 50 Church St.. New York, N. Y. '21 Abbott, A. N., Mines Supt., Mazapil Copper Co., LtdConcepcion del Oro, Zac., Mexico. '28 *Abbott, Argyle Campbell, Dev. Dept., E. I. du Pont de Nemours & Co., Wilmington, Del. '29 Abbott, Clarence E., V.P., Charge of Raw Materials, Tenn. Coal, Iron & R. R. Co., 1242 Brown-Marx Bldg.. Birmingham, Ala. '04 Abbott, Louis Benjamin, Chief Engr., Elkhorn Div., Consolidation Coal Co., Jenkins, Ky. '16 Abeel, George H., Jr., Cons. Min. Engr Box 427, Santa Monica, Cal. '18 Abel, Albert E., Asst. to Pres., Valley Mould & Iron Corp Hubbard, Ohio. '19 Abel, Raymond L., Asst. Prof., Dept. of Pet. Refin., Univ. of Pittsburgh Pittsburgh. Pa. '28 Abeel, Leo M., Research Engr., Sullivan Concentrator Chapman Camp, B. C., Canada. '31

Jan 1, 1929

By Y. L. Tian

Low-grade bauxite with A/S of 4.4 from Henan province was used as raw material and the selec-tive grinding of bauxite, grinding efficiency, particle size and Al2O3 and SiO2distributions of ground products were investigated using ball and vibration mills. The results show that the selective grinding can be used to realize the separation of aluminum from silicon within a certain particle size. The optimal grinding conditions of the ball mill with bauxite are as follows: grinding material to charge ratio, 1.2, charge volume ratio, 40%, pulp con-centration, 70wt%, medium size distribution, F30mm:F20mm:F15mm=20%:50%:30%. Under the conditions, the weight rate of ground product with A/S over 7.5 is 27% and the recovery of Al 2O3is 30%. The optimal grinding condition of the vibration mill with bauxite are as follows: grinding material to charge ratio, 0.9; charge volume ratio, 70%; concentration, 70%; medium size distribution, F40mm:F30mm:F20mm=20%:30%:50%. Under the conditions, the weight ratio of ground product with A/S over 7.5 is 25% and the recovery of Al 2O3is 27%. The research is significant for the rational and economical utilization of the low-grade bauxite.

Jan 1, 2014

Fossil fuel consumption in the United States increased markedly over recent years, and future demands expect to be even greater. Coal, this Nation's most plentiful natural fossil fuel, will play a key role in fulfilling these demands. With expectations of increased coal exploitation, the U. S. Bureau of Mines authorized this project, the objectives of whi.ch were to prepare an authoritative report on current surface coal mining technology, to define current problems and possible solutions, and to project future developments necessary to assure adequate surfaced mined coal production to meet the Nation's future energy needs. These objectives we're accomplished by an extensive review of available published literature and data gathering field visits to active surface coal mines throughout the country.

Jan 1, 1975

By U. B. Kodukula

The iron ore beneficiation plant at Serra-Azul Mines of ArcelorMittal, Brazil operates at a rated capacity of 3.2 million tons per year. The ore is concentrated using magnetic separation, jigging, hydrocyclones and spiral concentrators. The tailings from the process plant are generated from classifier overflow of 135 tons per hour dry solids and thickener underflow of 48 tons per hour dry solids. A systematic experimental program was carried out using Multi-gravity separator (MGS), and wet high-intensity magnetic separator (WHIMS) for recovering the iron values from both of the tailing streams while minimizing the total quantity of tailings to be discarded. The classifier overflow contained 32.3 percent iron, 49.9 percent silica and 2.18 percent alumina and was 45 percent finer than 45 microns in size. The thickener underflow sample contained 47.3 percent iron, 27.6 percent silica and 2.49 percent alumina and was 16 percent finer than 45 microns in size. Separation results on the classifier overflow sample with the MGS indicated that a concentrate containing 62.1 percent of iron, 10.8 percent silica and 0.36 percent alumina can be achieved with a weight recovery of 24.5 percent. The results with WHIMS at 6500 Gauss indicated that concentrate containing 62.6 percent iron, 8.3 percent silica, and 0.65 percent alumina can be achieved at a weight recovery of 34.7 percent. 4.7 percent. WHIMS studies at 6500 Gauss on thickener underflow sample indicated that a concentrate containing 61.4 percent iron, 8.8 percent silica, and 1.74 percent alumina can be achieved at a weight recovery of 57.2 percent. Based on these results, and further in-house test works, a WHIMS installation was adopted for the recovery of iron values from the tailings in the operating plant at ArcelorMittal Serra Azul Mines, Brazil.

Feb 23, 2014

Jan 1, 1903

By Louis J. Cabri

The ion microprobe (dynamic SIMS technique) is a very sensitive instrument for the quantitative determination of trace concentrations of precious metals (often at the ppb level) occurring in common sulfide minerals, either chemically-bound or as discrete particles too small for resolution by SEM. The technique involves sputtering a 250 x 250 Jim area of the grains to a depth of about one ILm and analysing the secondary ions emitted from a circular central region in the sputter crater with a 62.5 I'm diameter. The combination of quantitative mineral-specific sub-ppm analyses together with depth-profiling and the ability to produce secondary ion maps of trace precious metals makes this a very powerful technique in quantifying the precious metal distribution in refractory and other sulfide ores and process products. The technique is particularly well-established for analysis of gold-and platinum-bearing ores and process products.

Jan 1, 1996

By R. A., Pallanch

SO many variations of lead-zinc ores occur in nature that it is impossible to state any rules that will apply to the concentration of ores of this type. Some have lead and zinc in approximately equal amounts; others may have pre- dominant amounts of one or the other metal. There are gradations from all sulfide to completely oxidized minerals. Some such ores carry little pyrite, others contain much more pyrite than they do lead and zinc combined. The behavior of ores in flotation is largely a function of their lead-zinc ratios. their content of pyrite or pyrhotite, the nature of existing soluble salt conditions, the character of the gangue constituents: and the speed with which the minerals float. For the purposes of this paper only those lead-zinc ores handled commonly in present-day flotation practice will be considered. These are practically all-sulfide ores with relatively minor degrees of sulphatization or oxidation.

Jan 1, 1936

By Byron R. Berger

Disseminated Au-As-Hg mineralization is localized along the Getchell Fault system at the Getchell Mine in north-central Nevada. Replacement ore bodies occur in Cambrian carbonaceous limestone and limy shale beds. Cretaceous granodiorite, dacite porphyry, and andesite porphyry dikes parallel the fault zone and are spatially associated with the mineralization. Hydrothermal alteration and mineralization occur continuously along 4-5 km of the fault system, and extend more than 1 km down-dip. Alteration consists primarily of removal of carbonate and deposition of quartz, pyrite, and carbonaceous material. Marcasite, sericite, kaolinite, calcite, barite, and fluorite are common. Gold content reaches more than 43 ppm in parts of the altered zones and averaged 9.3 ppm in the mined ore bodies. For the mineralized zones as a whole arsenic averages 0.28%, and occurs primarily as realgar, orpiment, and arsenopyrite. Mercury (22 ppm) is finely disseminated and mercury-bearing minerals are seldom recognizeable. Accessory mineralization includes antimony (100 ppm), copper (47 ppm) , lead (18 ppm) , molybdenum (10 ppm) , tungsten (16 ppm) , and zinc (50 ppm) . Geologic field studies and K-Ar dating suggest that the mineralization is related to a hydrothermal system produced by the granodiorite and related dikes.

Jan 1, 1975

By R. G. Reddy

Viscosities of Feo-SiO2 slags were calculated using the previously developed structural based model. An expression was derived using hole theory and the atomic pair model to relate the NO0 and temperature to the viscosity. The deduced equation n=4.9x10-9 T1/2 NO0 exp (E/RT) poise was successfully applied to predict the viscosity of FeO-SiO2 slags in the composition range of 0.1 < XSiO2 < 1 for several temperatures. The calculated data agrees well with the experimental viscosity data.

Jan 1, 1991

By Keith L. Harris

The U.S. economy continued to grow moderately in the third quarter, but at a slightly higher rate than in the previous quarter. According to the Department of Commerce&apos;s preliminary estimate, real gross national product (GNP) grew at a seasonally adjusted annual rate of 3.3% during the third quarter of 1985, compared with a revised 1.9% for the second quarter and 1.6% for the third quarter of 1984 (table 1). Civilian unemployment dropped from the constant 7.3% rate between February and July to 7.0% in August and 7.1% in September. Employment on nonagricultural payrolls continued to increase (table 2), resulting in a continued rise in personal income, which in turn supported growing consumer purchases. Although purchases of services continued to provide the underlying foundation for the economic growth, the manufacturing sector received additional stimulus from significant increases in consumer purchases of durable goods, particularly automobiles. The increased demand for durable goods resulted in significantly higher industrial production for August and September, compared with levels attained previously this year (table 3). Capacity utilization increased to 80.5% in August but returned to 80.2% in September, matching the 1985 low previously reached in July (table 4). The real net export deficit grew only $0.2 billion in the third quarter; at $34.0 billion, however, it continued to exert a negative influence on the economy. On September 22, in an effort to reduce the deficit and make U.S. goods more competitive on world markets, the U.S. Government agreed to cooperate with the Governments of France, the Federal Republic of Germany, Japan, and the United Kingdom in attempting to lower the-value of the dollar in relation to other world currencies. Low inventories, rising factory orders and construction spending, the possibility of a lower U.S. dollar, and aggressive automobile production plans announced by domestic producers for the fourth quarter indicate the potential for an increase in manufacturing activity in the United States.

Jan 1, 1985

By Harry M. Mikami, Harold A. Heiligman

The term chromite is often used to cover all chrome ores and concentrates which are the designations actually employed by most industrial users and producers. Chromite is, of course, the predominant mineral in chrome ores which are aggregates of chromite and gangue minerals, most commonly magnesian silicates. Most chrome ores now used are petrographically chromitites which is a rock, rather than an individual mineral term. The title of this chapter, following past usage, is meant in the broad sense. Chromite is the only primary commercial source of chromium. This book is intended to deal only with nonmetallic minerals and rocks. Chromite uses are both metallic (ferroalloys) and nonmetallic (refractories and chemicals), but any discussion of mineralogy, geology, and mining is common for all types. A number of the major commercial ores are interchangeable, and their uses are determined by economic considerations. Mineralogy COMPOSITION [Chromite is a term embracing a wide range of chromium-bearing spinel*-group minerals the compositions of which can be expressed as (Mg,Fe2+)0.(Cr,AI,Fe3+ )203.t This can be further generalized to R2+O.R23+03 and the molecular RO: R,03 ratio is generally close to one. The exact composition may be arbitrarily expressed as a solid solution of six end-members, MgAI2O4, MgCr2O4, MgFe2O4 FeCr2O4, FeA12O4, and Fe2+.Fe23+04 with the proportions of each stated or plotted in the six-cornered prism of Johnston and Stevens61 or this scheme may be simplified to comprise only three endmembers making up a composition triangle, Fig 1. [ ] FIG 1-Triaxial composition diagram showing molecular compositions of chromites listed in Table 1. The RO.Fe2O3 corner includes Ti02 norms listed in the table. Note that the high-alumina chromites (1, 2, 3, 9), form a cluster well apart from the high-Cr2O3 chromites. There is a tendency for high-iron chromites to be higher in Fe2O3 + TiO2 but it is not a consistent or systematic relationship. The MgO/RO ratio must also be known to characterize the chromite chemically. Simplest and most convenient method is Thayer&apos;s&apos; in which a chromite such as (Mg.65Fe.352+)O.(Cr.40Al.50Fe.103+)203 would be written as (Mge,) Cr eAlo. The molecular pro- portions of ferrous and ferric oxides can be seen at a glance as the divalent and trivalent oxides]

Jan 1, 1960

By Benjamin W. Haynes

The Bureau of Mines, in cooperation with the National Oceanic and Atmospheric Administration (NOAA), has updated a 1977 NOAA report prepared by Dames & Moore entitled, "Description of Manganese Nodule Processing Activities for Environmental Studies." This updated report contains detailed flowsheets and descriptions of the five potential first-generation nodule recovery schemes now considered most likely to be used by industry; they are high-temperature gas reduction and ammoniacal leach, Cuprion ammoniacal leach, high-temperature and high-pressure H2S04 leach, reduction and HCI leach, and smelting and H2S04 leach. The first three processes are three-metal recovery schemes (Cu, Ni, and Co) with the option of Mn recovery from the tailings. The remaining two processes are four-metal (Cu, Ni, Co, and Mn) recovery schemes. All except the HCI process are assumed to use a nodule feed rate of 3 million tons per year (dry basis). Final metal products are Co powder and cathode Cu and Ni. A minor amount of Ni is also recovered as powder, and some Cu and Zn are recovered as mixed sulfides. Manganese in the four-metal processes is recovered as either manganese metal or ferromanganese.

Jan 1, 1983

By August Wendel

weight, and deflection, and recommends that the Pennsylvania Railroad Company denland that rails be made on specifications, based on these six variables, so narrow, that to fill them would cause the constant rejection of enormous quantities of steel, and a consequent enhancement of the price of rails, probably ten or twenty per cent., without any certainty that such rails would be any better than those the steel-mills are now making. I earnestly hope that the investigation which Dr. Dudley has so ably carried on will be continued. I hope the Pennsylvarlia Sailroad Company, or preferably a combination of several railroads, will institute the prolonged investigation which I think will be necessary to solve this deep problem; that they will take a hundred or more rails, watching and noting down carefully every detail of their manufacture as well as their analysis; that they will be carefully weighed before, during, and after service; that their crop-ends will be tested before service, and the rails themselves after removal; that all the sources of error which Dr. Dudley admits in the present investigation may be removed, and that enough facts may be gathered and tabulated so that the conclusions which may be drawn from them may be apparent to every one without labored discussion or heated argument. But I venture to prophesy that after this investigation shall have been completed, and a formula adopted which shall be satiefactory to both manufacturers and consumcrs, that formula will not be the one now under discussion. I hope Dr. Durlley will pardon me if I have been unduly severe in my criticism, and consider that I have written my remarks hastily and at a time which should have been given to needed rest. I differ with him only as regards the conclusions which he has drawn. I appreciate the value of his labors, and only make public my own conclusions in the hope of contributing to the advancement of the science of steelmaking, in which we are ail so deeply interested. Dr. August WENDEL, Troy, K. Y.: Dr. Dudley&apos;s last paper gives, certainly, very valuable and interesting information regarding the wear of rails under different conditions. His results concernillg the composition of rails, explotle, rather startlingly, some old theories regarding the wear of rails, and 1 think after his formula is silnplified it will be one good formula to work by. As he now arrives at the same conclusions reached ill his first paper, some of my remarks will apply to both, althougl~ I would

Jan 1, 1881

By Ingunn Opland, Silje M. Tinderholt

Drill and blast project in Norway’s capital. The contract consists of 7 rock caverns (350–950 m2), 9.2 km tunnels, and four shafts. With 110 blue-collar and 31 white-collar, the project produces an average of 16–21,000 m3 hard rock per week, with a total of 19 tunnel faces. Weekly, nine grouting rounds for water control, 800 m3 shotcrete, and 1,200 bolts are required, and 60 trucks leave the site pr. day. Challenges include blasting in densely populated areas, planning and coordination to maintain high production, obtaining a CEEQUAL certification of very good, and transporting rock on Oslo’s main highway.

Jun 13, 2023

By J J. Frausto, G R. Ballantyne, M S. Powell, R Cruz, K Runge

Hydrocyclones are the most widely used device for classification in a grinding circuit. However, even the most efficient hydrocyclone has a bypass of fines from the feed to the underflow which reduces comminution circuit performance, as well as misclassification around the cut point. Fine screens classify only according to the particle size, allowing for a reduction in the recirculation of fines back to the mill. The development of high capacity multi-screens makes fine classification in a grinding circuit a viable option. Minera Saucito recently substituted hydrocyclones with screens in its grinding circuit. The change of classifier resulted in an increase in throughput and lead recovery but a decrease in silver recovery. This case study presents the changes in comminution and flotation performance that occurred after the installation of screens and uses historical operational data collected over 12 months of operation to investigate the reasons for these observed changes. CITATION:Frausto, J J, Ballantyne, G R, Runge, K, Powell, M S and Cruz, R, 2017., in Proceedings MetPlant 2017, pp 298–314 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By E. F. Loiseau

Until June, 1868, it had not been attempted, either in this country or abroad, to manufacture by mechanical means, from anthracite coal-dust, artificial fuel for domestic use. Several attempts had been made to utilize coal-waste by converting it into a fuel for manufacturing purposes, but none of the processes were original, and they were merely applications of the well-known European processes and machinery, slightly modified by American ingenuity and mechanical skill. With one exception all those attempts have been failures. The great difficulty in the application of European processes and machinery has always been the limited production, and the excessive cost of the manufactured product, as compared with the cost of mining and preparing the ordinary anthracite coal for the market. The only serious and intelligent attempt to manufacture, on a large scale, artificial fuel for manufacturing purposes, has been made by the Anthracite Fuel Company, whose works are erected at Fort Ewen, near Rondout, New York. This company, organized under the auspices of the Delaware and Hudson Canal Company, had to go through the usual course of difficulties, breakages, and disappointments, which seems to be the lot of every new industry. Thanks, however, to the energy and perseverance of Mr. L. L. Crounsse, a gentleman of means, from Washington, D. C, the enterprise succeeded, and it is to-day established on a permanent basis. In order to increase the production, and to reduce its cost, the Anthracite Fuel Company was compelled to change most of its •plant, and to erect more powerful machinery, producing lumps of a larger size, almost twice the size of the lumps made previously by the same company. This increase in the size of the lumps has been resorted to in Europe as well as in this country, in order to increase

Jan 1, 1879

By Sven Petersen

In April 2010 three REMUS6000 series autonomous underwater vehicles (AUVs) have been used to simultaneously map large areas near the Mid-Atlantic Ridge (3°N) axis in water depths ranging from 1,000m to 4,000m. One vehicle was provided by the Leibniz-Institute for Marine Science, IFM-GEOMAR (Kiel, Germany) the other two were provided by the Waitt Institute for Discovery (La Jolla, USA) and managed by the Woods Hole Oceanographic Institute (USA). The REMUS6000 vehicles, manufactured by Hydroid Inc. (USA), are "cigar-shaped" vehicles (4m long and weighing approx. 900kg) and consist of a tapered forward section, a cylindrical midsection and a tapered tail section. An internal titanium strongback, which extends through much of the vehicle length, provides the structural integrity and acts as a mounting platform for syntactic foam, equipment housings, various sensors and release mechanisms. The AUVs can be used in various payload configurations such as multibeam bathymetry, electronic still camera, or subbottom profiler. For these missions the electronic still camera configurations was installed. An EDGETECH 2200M dual frequency (120/410 kHz) side scan sonar was used to map the seafloor, but other frequencies are readily available for more options in resolution and range. The 120 kHz side scan transmitter was used for most missions in order to map large areas (increased range) and to be able to fly at higher altitudes (between 70m and 90m) above the rough seabed encountered in this area. The maximum slant range was between 600m and 700m on both sides resulting in a swath width of up to 1.2 km. Line spacing ranged from nearly 1,000m in flat areas down to 400m in steep terrain. Side-scan mosaics were generated with a 1m resolution. Selected areas were targeted by the higher resolution 410 kHz transmitter as well as by bottom photographs flying as low as a few meters above the seabed. The vehicles navigated autonomously using a combination of inertial navigation (Kearfott T-24 or T-16 INS) and long baseline acoustic navigation by computing their range to two moored acoustic transponders. Working efficiently in this rough topography at speeds above 3 knots was only possible due to the obstacle avoidance capabilities of these AUVs.

Jan 1, 2011