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By Leonardo de Oliveira Turani

A energia eólica, fonte de energia renovável e de baixo impacto ambiental, vem crescendo rapidamente na última década, em especial no Brasil. A conversão da energia cinética dos ventos em energia elétrica é realizada por aerogeradores, que são acopladas em torres, que na sua maioria são constituídas de anéis sobrepostos de aço, os quais são fabricados e montados com o emprego de várias etapas de soldagem. Em função disso, o conhecimento da soldabilidade dos aços estruturais é um fator importante para indústria eólica, dando subsídios para a elaboração de procedimentos que permitam a redução dos custos de soldagem e a seleção adequada dos aços empregados. Este trabalho objetivou a avaliação da soldabilidade do aço estrutural EN 10025-4 S355M através de ensaios mecânicos e metalográficos de juntas soldadas pelo processo de arco submerso (SAW) em duas diferentes técnicas: Single Arc e Tandem Arc. Os resultados mostraram que o aço S355M apresentou excelente soldabilidade, com destaque para o processo SAW Tandem Arc, o que possibilita a maior exploração desta técnica como uma excelente alternativa para a redução do tempo de soldagem durante a fabricação de torres eólicas.

Aug 8, 2018

The Library of the above-named Societies is open from 9 A. M. to 10 P. M. except on holidays. It contains about 70,000 volumes and 90,000 pamphlets, including sets of technical periodicals and publications of scientific and technical societies. Members of the Institute, with few exceptions are forced to spend a portion of their time in localities isolated from sources of information. To these the Library; through its Library Service Bureau, can render valuable service through correspondence; letters requesting information will receive especial attention: The Library is prepared, to furnish references and photographic copies of articles on mining and metallurgical subjects; to determine the existence of mining maps, and to furnish general Information on the geology and mineral resources of-all countries. All communications should be made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape. HARRISON W. CRAVER, Director.

Jan 4, 1919

By E. Ghali, B. Arsenault

Aluminum alloys play an important role in the manufacturing of air and ground vehicles. However, with such alloys, corrosion damage is often found on structural components subjected to fatigue loading. The alloying provides large benefit in terms of the high specific tensile strength (ultimate strength/density ratio) to the aluminum alloy but causes the aluminum alloy to be more sensitive to localized corrosion due to complex microscopic heterogeneities such as secondary phases. This paper investigates thermal spray coating namely arc spraying to evaluate the protection against environmentally assisted cracking (EAC) and localized corrosion on Aircraft structural 7075 T651 aluminum alloys. In particular, EAC and pitting corrosion at the interface coating-substrate are a challenge for thermal spray protective coatings on aluminum alloys under cyclic load and immersion. To address these issues, different surface preparation techniques prior to arc spraying were considered such as chemical de-oxidation, laser ablation, shot peening and grit blasting. Results indicate that surface preparation and improved coating process parameters play an important role to provide a coating conferring a protection against both localized corrosion and EAC.

Jan 1, 2006

By Guido del Castillo

El presente trabajo describe la aplicación y empleo de arcos de acero como medio de sostenimiento de galerías en las minas metálicas donde condiciones especiales y fortif¡caciones muy pesadas hacen imposible o antieconómico el uso de los tipos de sostenimiento.

Sep 1, 1961

Continued discussion of the paper of R. W. Raymond, presented at the Cleveland meeting, October, 1912, and printed in Bulletin. No. 70, October, 1912, pp. 1111 to 1122. See also discussion printed in Bulletin No. 74, February, 1913, pp. 319 to 329. R. B. BRINSMADE, Puebla, Puebla., Mexico (communication to the Secretary *) :-Though I heartily approve of several minor points emphasized by Dr. Raymond (such as the general desirability of local administration, rather than Federal, and the evils inseparable from the Federal Apex Law), I feel obliged to dissent from his four final propositions. As Dr. G. 0. Smith has already discussed these propositions from the standpoint of the experience of other countries, I shall base my criticism upon certain general economic principles, which will be grouped under the following five topics: 1. The dual theory of property. 2. The essential factors in fixing prices. 3. The relation of land ownership to the distribution of wealth. 4. The relation of land ownership to speculation and development. 5. The relation of land ownership to the political power. I shall give here only a brief outline of these topics, as they are fully treated in the standard treatises on political economy.1

Jan 5, 1913

By James R. Coldwell

Mining and processing cost analyses were conducted by the U.S. Bureau of Mines on massive sulfide copper-zinc and low sulfide vein gold deposit types that may be found in the Ketchikan Mining District. Reserves and recoverable metal values (RMV) needed to make these deposits economically viable were modeled. Methods for estimating ore grades and required RMV are presented. Economic modeling for massive sulfide deposits indicated the RMV necessary for a 15% Discounted Cash-Flow Rate-Of-Return (DCFROR) for an underground cut-and-fill mine ranged from $137/mt for a 6,100 mtpd on-site milling operation to $526/mt for a 450 mtpd off-site milling operation. On-site milling was always less costly than off-site milling. Economic modeling for low sulfide vein gold deposits indicated the RMV necessary for a 15% DCFROR for an open-pit mine, off-site mining operation ranged from $S4/mt at 2,900 mtpd to $71/mt at 360 mtpd, and from $49/mt at 2,900 mtpd to $100/mt at 360 mtpd for an on-site milling operation. Off-site milling was less costly than on-site milling until production exceeded approximately 1,700 mtpd. Then, economies of scale reduced operating costs enough to offset the higher capital costs required for on-site milling.

Jan 1, 1995

By J. F. Lewis

Believing that one of the essential points in mining, as in all other business, is to know the expense incurred in each particular department, I have carefully kept an account with each department for the past three years; and, as it may be of interest to some of our members, I herewith present it to the Institute, reduced to per centages of the total yearly expense, showing the cost for materials, repairs, expenses, tools, team accounts, powder, oil, and fuel, also for labor under its several heads: 1875—Materials. 1875—Labor, Repairs,...040 Expenses,....016 Team,. .. .. .017 Machinery,. .. .055 Tools,..006 Repairs,. .. .027 Improvements,.....030 Washer,. .. .076 Oil ..008 Pit,.. 178 Powder,..,043 Dirt,.. 130 Fuel,. .325 Superintendence,. ..050 .485 .516 100.1 1876—-Materials. 1876-Labor. Repairs,. . • .. .043 Expenses,......012 Team,.011 Machinery,. .. .090 Tools,..005 Repairs,... 027 Improvements,.....007 Washer,. .. .085 I,. ...,015 Pit,.. 139 Powder,. .. .. .030 Dirt,.. 160 Fuel,...321 Superintendence,. ..078 .444 .559 100.3 1877—Materials. 1877—Labor. Repairs,......102 Expenses,......019 Team,..031 Machinery,. .. .050 Tools,..030 Rrpairs,. .. .046 Improvements,....,031 Washer,. .. .057 I,...009 Pit,.....179 Powder,...035 Dirt,.. 162 Fuel,...200 Superintendence,. ..054 .457 .548 100.5 Average for the three years 1875, '76, and '77. Materials. Labor. Repairs,...062 Expenses,...016 Team,..016 Machinery,. .. .065

Jan 1, 1879

By T. H. Alden

BaCKOFEN, Avery, and Turner have shown"2 that the large tensile elongation in superplastic metals is correlated with a high strain-rate sensitivity of the flow stress. At present, the reported superplastic materials are complex eutectic or eutectoid systems with a large solubility range in at least one of the terminal phases. This note describes the behavior of a solid-solution alloy (at 22°C)5,= Sn-1 wt pct Bi, which has been processed in order to produce a fine grain size.2,3,6 The chill-cast, 1/2-in.-diam ingot was homogenized for 1 week at 130°C, extruded at O°C to 0.083 in. diam, quenched within 15 sec, and stored at -196°C. Samples were warmed to room temperature 16 hr prior to mechanical testing or metallography. During tension testing at room temperature, it was found that the flow stress reached a steady-state value which depended on the imposed elongation rate and was independent of strain to an error of about ±5 pct. In Fig. 1 is plotted log a vs log e where a is the measured steady-state flow stress and i the imposed strain rate. These quantities were calculated using "instantaneous" area and length to an accuracy in the sample diameter of ±5 x 10-4 in. The log a-log 1 curve is sigmoidal. The strain-rate sensitivity, which may be given by d log old log 6,' has a maximum value of about 0.48 between i = 5 x 10-4 and 5 x 10-3 per min. The value is well above frequently measured values for metals at creep temperatures (0.1 to 0.3) and comparable to the rate sensitivity for Pb-Sn solder: which has been shown to be superplastic.2,3 Note, however, that below or above the strain rate of 10-3 per min the rate sensitivity of Sn-1 pct Bi decreases and at high rates is more nearly like that of conventional metals. The grain size of this material is relatively uniform, Fig. 2, and may be specified by an average linear intercept i.' Grain growth occurs at room temperature but after 16 hr, L = 5. Tensile elongation was measured on finer-grain-size specimens, which had been at room temperature 15 min prior to testing. After 15 min, the samples are fully recrystallized. Three strain rates, 5 x 10-3, 10-2, and 2.5 x 10-2 per min, were employed for which the measured elongations varied from 425 to 500 pct. These results would seem to justify the term superplastic, applied to this alloy, although the ductility is inferior to that of the Sn-Bi eutectic.3 The Sn-1 pct Bi alloy, which is a single-phase material with equiaxed, fine grains, is an excellent one on which to make an estimate of the Nabarro-Herring9 creep rate. According to the model of Avery and Backofen2 a substantial part of the deformation must be accomplished by N-H creep in the strain rate-temperature regime in which d log a/d log 1 = 0.5. The maximum N-H creep rate is given by9 L2kT where v is the atomic volume and D the self-diffusion coefficient. For this test v = 3.O x 10-23 cu cm, D = 1.4 e-23,300/RT = 2.5 x 10-l7 sq cm per sec,7 L = 5x 10+4 cm, T = 295°K, and a = 2000 lb per sq in. = 1.38 x 10' dyne per sq cm. The calculated creep rate is E= 4 x 10-11 per sec which may be compared with the measured creep rate at this stress, Fig. 1, of 6.7 x 10-5 per sec. The N-H creep rate is seen to be negligible. Earlier consideration2 of this question was in error because incorrect diffusion coefficients were used. The assistance of R. R. Russell in metallography is acknowledged gratefully.

Jan 1, 1967

By John M. Karpinski

A method and equipment have been developed Tor measuring the impact strength of grains of brittle materials. It is shown that brittle materials develop a characteristic particle size distribution when fractured by impact. A simple mathematical model has been found to describe this distribution, and one of the parameters of the model has been designated the r value. The r value is directly proportional .to impact energy and, for fixed impact energy, it becomes a useful criterion of grain strength. Data are presented on the variation of the r value as a function of sample history, initial size, energy input and number of impacts, The results are interpreted in terms of the flaw theory of brittle fracture.

Jan 1, 1964

By L. W. Beckstead

In a conventional zinc refinery plant, zinc concentrates were roasted at 950°C. The calcine was ground and leached in a series of leaching vessels using sulfuric acid. The pH in the first leaching vessel was maintained at 2.5, while the pH of the solution exiting the last vessel was about 5.4. The leached residue typically contained (in percent) 0.1 Ag, 0.2 As, 0.7 Cd, 2 Cu, 15 Fe, 10 Pb, and 15 Zn, and it was classified as hazardous material according to the EP-toxicity test. In order to make the residue non-hazardous, and to recover most of the metal values from the residue, a brine leach process was developed. The process consisted of leaching the zinc leach residue in CaCI, brine solution at pH 2 for 1 hour at 90°C. Silver extraction was about 95 percent, while lead, copper, cadmium, zinc, and iron extractions were about 80, 50, 50, 30, and less than 0.5 percent, respectively. More extreme conditions of acidity could have been used in the leaching stage to increase zinc dissolution, but iron dissolution would have significantly increased which would have complicated subsequent recovery steps. The leached and washed residue passed the EP-toxicity leach test and could be disposed as non-hazardous. Silver, copper, and lead in the leach solution were recovered by zinc cementation, while zinc and cadmium were recovered by sulfide precipitation. The resulting solution can be recycled in the process after magnesium precipitation.

Jan 1, 1993

By C. J. Gauvin

The Geological Department, headed by the Chief Geologist, is part of the General Engineering Division and is under the direct supervision of the Chief Engineer. The Geological Department is responsible for the technical direction of all work concerned with the finding and outlining of ore. It provides the mine operating staffs, with the necessary plans and sections to enable them to design pit and underground layouts and to, extract ores' as required by outgoing cargoes. The department maintains grade and ore reserve statistics in conjunction with a mining recovery factor at year-end. These duties are performed through the co-operation of all departments participating in the overall operation. As a result, a steadily broadening use is being made of geology at Steep Rock.

Jan 1, 1960

By R. L. Stein

For the past several years, the Bureau of Mines has been actively engaged in developing two new oxygen self-rescuers through research contracts with private industry. These new oxygen self-rescuers are designed to be carried by a miner while he is at work and are used during emergency escape, supplying high-purity oxygen to the user and, at the same time, absorbing carbon dioxide (C02), The first of the two new self-rescue breathing devices is a 10-minute, self-contained apparatus developed by the Mine Safety Appliance Co, Size and weight of the unit are comparable to the currently used self-rescue devices. The second device, designed and developed by Lockheed Missiles and Space Corp., is 8. 4.5-lb package which supplies 1 hour of oxygen to the miner. Both devices have a canister which contains the oxygen-producing and CO2-absorbing potassium superoxide chemical, a breathing bag, a bite-type mouthpiece, noseclip, goggles, and hoses connecting the canister and mouthpiece. When needed in an emergency, the miner removes the outer protective cover and dons the unit. For both devices oxygen is immediately available once the mouthpiece is placed in the mouth. These two new units have received prototype approval from the National Institute for Occupation and Safety Health (NIOSH) and the Mining Enforcement and Safety Administration (MESA).

Jan 1, 1976

By Wallace W. Key

Problems of marketing industrial minerals to chemical manufacturers are manifold. In addition to the difficulty of establishing demarcation lines between "crude" and "processed" industrial (nonmetallic) minerals, and "industrial mineral compounds" further uncertainty exists because some chemical manufacturers do not talk the same language as the industrial mineral producer. For example, paint technologists use "rutile" and "anatase" to describe highly refined chemical compounds. The earth scientists use these terms to describe naturally occurring minerals. Further, marketing research problems are intensified because of the overlapping data of the Standard Industrial Classifications (SIC) groups, and the inexactness of "Chemical Industry," "Chemical and Allied Products Industries," and "Chemical Process Industries," which are widely variable in meaning but are often used interchangeably. Bureau of Mines information Circular 8244, "Minerals for Chemical Manufacturing," was the out¬growth of an attempt to unravel some of the problems caused by overlap of statistical data compared with actual industry practices. Using this study as a base, specific industrial mineral applications of some important sub-industry groups were analyzed for the; California chemical industry. Differences between local and national practices were compared. Practices usually differed, depending on cost and availability of alternate minerals, climate, idiosyncrasies, local regulations, and other conditions. Bureau of Mines Information Circular 8260, "Mineral Fillers for the California Pesticides Industry," is the first such analysis of, a sub-industry group. Other such studies are underway. Obtaining national data is easy, but to be able to compile meaningful information which can be revealed on a regional and State basis generally is difficult and often impossible. This paper will briefly emphasize some of the industrial mineral problems encountered, and bring out the needs and benefits being derived through the continued cooperation of authoritative officials concerned with supply and consumption of industrial minerals in government and industry.

Jan 1, 1965

By Magnus Troilius

The heat-calculations of gas-analyses involve cumbrous multiplications, which are apt to lead into errors. The foliowing tables and formulae have been found useful as facilitating such calculations, and therefore I hope that they will be of interest to some of the members. By "heat-unit" will, in the following, be understood the amount of heat required to raise the temperature of 1 kilogram of water l° Cent. All the tables refer to cubic meters at O0 and 760 mm. pressure. The following gas is chosen as an example: C02, - 4.0 vol. per cent. co, = 20.0 " CHI, - 3.5 " H, - 7.0 " N, - 65.5 " " 100.0

Jan 1, 1884

By Edward F. Divers

The Bureau of Mines recently tested a sideboard device that is designed to act as an extension of conventional brattice, thus improving face ventilation of developing room-and-pillar-type coal mining. In these laboratory tests, an 8-foot-long rigid sideboard was mounted vertically along the left fender of a full-scale-model ripper-type continuous mining machine, rising to the mine roof to provide an air seal. It extended from the auger support frame pivot point outby along the fender. A novel water spray manifold was used to form an air seal between the sideboard and brattice. Tests showed improvement in face ventilation with the prototype device, and also demonstrated that water sprays can form an effective air seal over a fairly wide pressure range. Based on this preliminary study, subsequent improvements may make the sideboard concept much more effective, thus affording a simple, inexpensive technique to improve the effectiveness of face ventilation.

Jan 1, 1979

By E. V. Leont'eva, V. R. Vafin, A. G. Kladova, N. L. Medyanik, A. P. Ponomarev

"The thermochemical technology for recovery gold, silver from mature flotation tailings of pyrite ores by two-stage sintering with chlorine-ammonium reagents and leaching of bakes with water is developed. The economic effect of the technology implementation is calculated. KEYWORDS Gold and silver recovery, mature flotation tailings, pyrite ores, chlorine-ammonium reagents, leaching INTRODUCTION The relevance of processing the technogenic reserves of ore mining and concentration wastes accumulated over the long operation periods of mineral deposits is beyond doubt. Hundreds of tons of precious and non-ferrous metals that were not recovered during the primary processing are concentrated in the accumulated wastes. For example, tailing storage facilities (TSF) at the mineral processing plants in the Southern Urals region of Russia hold more than one hundred tons of gold and thousands of tons of silver in the mature flotation tailings (MFT) of copper pyrite ores. Secondary processing of technogenic materials is facilitated by the fact that they are preprocessed — ground and compactly deposited on the surface, but complicated by the low (compared to ores) grade, uneven distribution of the valuable minerals, altered and unstable material composition of the mineral feed. This leads to low recovery rates of valuable metals by conventional physicochemical processing methods. It is necessary to develop innovative methods of deep integrated processing of industrial wastes, based on the study of the material composition of specific technogenic mineral resources and based on ensuring the environmental safety of the resulting secondary waste. MATERIALS AND METHODS The object of this study are the MFT of Uchaly Concentrator in the Republic of Bashkortostan, Russia, which processes copper pyrite and copper-zinc ores. According to the data of particle size, chemical, X-ray phase, and optical microscopic analyzes, samples of the MFT are characterized by considerable particle fineness (the fraction of the size class -41 µm is 89-90%), low grade of gold (1.7-2.0 g/t) and silver (18.0-19.5 g/t), comparable grades of iron (23.0-26.8%) and sulfur (28.1-28.7), but different grades of copper (0.12 - 0.73%) and zinc (0.34-1.26%). The most common mineral in the samples is pyrite (50 - 56%), found in intergrowth with grains of other sulfides (0.1-4%) - sphalerite, tennantite, chalcopyrite, covellite. Quartz and aluminosilicates are the dominant rock minerals (21-36%). Based on the results of the phase analysis, it was established that approximately 70% of the gold in the samples is found in a form that is resistant to cyanidation — it is locked in sulfides (52-56%) and quartz and coated by films. Along with sulfides and rock minerals, common gold and silver minerals (chalcogenides, intermetallides, native gold) in the form of submicro- and nano-sized precipitates are also associated with intergrowth of a complex structure. These features of the material composition allow classifying the MFT of the pyrite ores as a mature feed material and emphasize the need for chemical non-cyanide methods to recover gold and silver from the mature minerals and associations they are found in."

Jan 1, 2018

By Juan Carlos Ramírez

En los últimos años se desarrollaron sistemas para la generación de paredes finales en yacimientos de cielo abierto y así proveer la pared adecuada a los parámetros que alimentan el sistema. Por tal motivo, el objeto del texto es realizar un estudio comparativo entre los dos sistemas de generación de paredes finales: Pushbacks y Whittle 3D. La aplicación de ambos sistemas se ejecutó a través de dos etapas en la mina Cuajone donde el sistema Pushbacks guió el diseño de paredes finales de mina desde 1984 hasta 1989. Mientras que el segundo, se utilizó desde 1989 hasta la actualidad puesto que es un sistema optimizador computarizado que permite obtener paredes finales óptimas en yacimientos explotables a cielo abierto de forma segura.

Apr 1, 1991

By D. S. Kingery

Investigations over several years have disclosed that the principal manners of occurrence of shuttle-car injuries are in order: 1. Victims in contact with roof or crossbars. 2. Victims in contact with ribs or timber legs. 3. Victims falling from, or jerked from, shuttle cars. 4. Victims in contact with overhanging brows or protruding pine for pin timbers, or water lines. 5. Contact with persons or collisions with parked equipment. 6. Victims injured by roof falls or falling timbers caused by knocking out roof supports with shuttle cars. 7. Victims injured by runaway shuttle cars. 8. Victims injured while loading or unloading timbers or other materials from shuttle cars. These recurring types of shuttle-car accidents reflect the physical conditions of the working sections, certain safety deficiencies in shuttle-car maintenance and design, and unsafe practices by operators.

Jan 1, 1952

Prior to 1972, Peko Mines Limited at Tennant Creek used a central mill at Peko, which consisted of a gravity circuit, flotation and cyanidation of tailings, to treat their gold ore from surrounding mines. The Warrego concentrator, 60km to the west, was built to handle the Warrego and Gecko copper orebodies, which were being developed concurrently with the concentrator construction The Warrego concentrator consisted of a flotation circuit, using autogenous grinding at 100 - 120 tph, compared to the more elaborate Peko circuit employing rod mill - ball mill grinding capable of treating only 18 - 26 tph. During development of the Warrego copper mine a gold rich ore pod was located, because of which the mining plans were adjusted to allow simultaneous, separate extraction of the copper and gold ores. However, the plans for the concentrator were not affected as the gold ore could be carted 60km to the Peko central mill for processing.

Jan 1, 1978

By Felipe E. Olivares S

"El presente texto revisa el origen y distribución de los metales raros como parte de un proyecto de recuperación de subproductos de valor comercial en la fundición de La Oroya. Para ello se reeexaminan ocho minerales raros (bismuto, selenio, teluro, cadmio, talio, indio, bismuto, indio de alta pureza), cuya composición de elementos raros se registra en la concentración de algunos productos o residuos. Estos minerales son del grupo del cobre Chalcópirita, Enargita, Tetrahedrita, Bornita y Chalcosita; del plomo: la Galena, Jamesonita y Gratonita, y la Esfalerita que proporciona el zinc. Los concentrados y minerales que entran al proceso de fundición se reparten en tres circuitos principales: cobre, plomo y zinc. Los circuitos de los primeros están ligados entre sí por el sistema de Cottrelles y los procedimientos de las mismas fundiciones, mientras que el último actúa de forma independiente. Por último, es competencia del Departamento de Investigaciones, la recuperación de dichos subproductos a través del proceso de concentración y fundición, como de a búsqueda nuevos métodos en el campo minero y metalúrgico. "

Jul 20, 1956