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By André Brasil

Dado que las represas de relaves construidas por el método de aguas arriba presentan deficiencias relacionadas con los aspectos constructivos y de seguridad, es difícil evaluar la variabilidad real del depósito basándose apenas en los procesos de campo. En ese sentido, el presente texto desarrolla un modelo para describir y simular el mecanismo de formación de las represas de relaves considerando las variables externas (concentración y caudal de descarga) e internas, así como muestra soluciones analíticas y numéricas comparados a nivel laboratorio.

Sep 9, 2007

By Chantale Doucet

L?utilisation du remblai en pâte dans les exploitations en vrac est de plus en plus importante. Puisque la technologie existe pour fabriquer du remblai en pâte sans construire une usine coûteuse, il est maintenant possible d?élargir le domaine d?utilisation du remblai en pâte pour y inclure des gisements filoniens où le besoin annuel de remblai est moindre. Dans certains cas, l?utilisation du remblai en pâte pourrait permettre de réaliser d?importantes économies telles que la réduction de la dilution, la stabilité des ouvertures, la récupération d?une plus grande partie du minerai par la réduction de la taille des piliers et l?entreposage de moins de résidus à la surface. L?ampleur des économies est parfois difficile à chiffrer mais il est tout de même important d?en tenir compte lors de la décision d?utiliser du remblai en pâte puisque ce sont souvent ces économies qui seront déterminantes. Différentes méthodes d?extraction avec remblai en pâte appliquées aux mines filoniennes seront présentées. Des défis et les solutions reliés à l?utilisation du remblai en pâte à la Mine Doyon seront discutés.

Oct 1, 2001

By Wade A. Narin, James K. Mitchell

Hydroblasting is considered a distinct soil improvement technique from explosive compaction, though the blast designs for the two techniques are similar. Hydroblasting is a three step process developed for densifying unsaturated, collapsible soils, especially loess. The required steps are: prewetting the soil to an adequate saturation, placing and detonating the explosive charges, and consolidating the soil (squeezing the water out of the pore spaces between the soil particles under gravity) to a denser state.

Jan 1, 1995

Mine planners must select a single pit for design with the knowledge that the grades on which this selection is made are uncertain. This uncertainty is often ignored through the use of deterministic models of grade. This makes the mine planner?s job simpler but does not necessarily lead to the ?correct? or ?best? selection. Grade uncertainty is typically modeled with conditional simulation, which generates multiple possible realizations of grade that are equally probable (or improbable). M ethods for incorporating grade uncertainty into mine planning to date have either been perceived as being too complicated, not accessible or too time-consuming. This paper proposes a simple and efficient modeling approach to incorporating conditional simulation into pit optimization, which would be able to be applied in currently commercially available software. An example for R esolute M ining Ltd.?s Syama gold project in M ali shows the range of ore, grade and value outcomes associated with generating pits through a variety of methods.

Jan 1, 2013

By Joseph A. Holmes

Although Venezuelan production attained a new peak in 1938, passing the 190 million barrel mark for the first time, there was a distinct flattening of the steep upward trend that marked 1937 and preceding years. The annual total of 190,231,780 bbl. was only 31/3 million barrels above the 1937 figure, an increase of slightly less than 2 per cent, which contrasts sharply with the 20 per cent increase of 1937 over 1936. As in the previous year, the Lake Maracaibo fields supplied approximately 73 per cent of the oil produced, Lagunillas remaining the largest single contributor in spite of a 17 million barrel decrease in its annual output. Tia Juana increased its percentage of the Venezuelan total from 14.1 per cent in 1937 to 23.4 per cent in 1938; La Rosa showed little change with 13.7 per cent; Quiriquire in eastern Venezuela was also little changed with 13.2 per cent; Mene Grande, the only other field of real importance, declined from 7.7 per cent of the total in 1937 to 6.6 per cent for 1938. Two new fields, Temblador and Bachaquero, began actively to ship oil during the year, and by November were averaging 7600 and 10,000 bbl. per day, respectively. The former is in eastern Venezuela, and the latter is the most southern of the proven Lake Maracaibo fields. (A map of Venezuela was published in Volume 127 of the Transactions.) Table 1 gives a complete résumé of Venezuelan production by fields for 1937 and 1938, and shows that 1,685,575,663 bbl. had been produced to Dec. 31, 1938. The percentage contributed by each of the principal fields to this total is shown in Table 3, as well as their trends over the past several years. From these data it is apparent that the Maracaibo Basin is the principal source of Venezuelan production, and will probably continue to hold this position for some years. At the year's end 2657 oil wells were producing, of which 2425 were in western and 232 in eastern Venezuela; 36 per cent were on natural flow, 57 ppr cent were pumping, and 7 per cent were on air or gas lift. Out of 523 wells drilled, 507 producers were completed in 1938, five less than in the previous year and nearly 100 less than in 1929. These

Jan 1, 1939

By Joseph A. Holmes

Although Venezuelan production attained a new peak in 1938, passing the 190 million barrel mark for the first time, there was a distinct flattening of the steep upward trend that marked 1937 and preceding years. The annual total of 190,231,780 bbl. was only 31/3 million barrels above the 1937 figure, an increase of slightly less than 2 per cent, which contrasts sharply with the 20 per cent increase of 1937 over 1936. As in the previous year, the Lake Maracaibo fields supplied approximately 73 per cent of the oil produced, Lagunillas remaining the largest single contributor in spite of a 17 million barrel decrease in its annual output. Tia Juana increased its percentage of the Venezuelan total from 14.1 per cent in 1937 to 23.4 per cent in 1938; La Rosa showed little change with 13.7 per cent; Quiriquire in eastern Venezuela was also little changed with 13.2 per cent; Mene Grande, the only other field of real importance, declined from 7.7 per cent of the total in 1937 to 6.6 per cent for 1938. Two new fields, Temblador and Bachaquero, began actively to ship oil during the year, and by November were averaging 7600 and 10,000 bbl. per day, respectively. The former is in eastern Venezuela, and the latter is the most southern of the proven Lake Maracaibo fields. (A map of Venezuela was published in Volume 127 of the Transactions.) Table 1 gives a complete résumé of Venezuelan production by fields for 1937 and 1938, and shows that 1,685,575,663 bbl. had been produced to Dec. 31, 1938. The percentage contributed by each of the principal fields to this total is shown in Table 3, as well as their trends over the past several years. From these data it is apparent that the Maracaibo Basin is the principal source of Venezuelan production, and will probably continue to hold this position for some years. At the year's end 2657 oil wells were producing, of which 2425 were in western and 232 in eastern Venezuela; 36 per cent were on natural flow, 57 ppr cent were pumping, and 7 per cent were on air or gas lift. Out of 523 wells drilled, 507 producers were completed in 1938, five less than in the previous year and nearly 100 less than in 1929. These

Jan 1, 1939

By I. B. Cadoff, J. C. Bilello, R. Rosenberg

Diffiusion of magnesium into the surface of LiF crystals to controlled depths and subsequent heat treatments provided a wide range of surface zone harahesses and structure, The bend strength of the LiF crystals was increased by as much as an or-dev of magnitude. Ductility was achieved when dislocation generation occurred in the diffusion zone or when dislocations penetrated to the surface from the intevior. A critical surface hardness of 130 to 140 kg per sq mm was found helozu which generation could take place in the diffusion zone and ahoue which the zone was impenetrable, This hardness was obtainable by several methods, among them the aging of quenched MgF2 -LiF solutions to produce MgF, precipitation. Maximum hardness was ohtained in quenched specimens with no visihle evidence of MgF,. Diffusion-zone formation followed a parabolic rate law and an activation energy of 20.9 kcal per mole was obtained for the process. RECENTLY, the properties of ionic crystals as related to surface condition have been receiving much attention, specifically the transitions between ductile and brittle behavior. Originally Joffe 1 showed that NaCl crystals could be made ductile by immersion in water and related this to the elimination of surface microcracks. Aerts and DeKeyser 2 and Gorur 3' have subsequently shown that ionic crystals are inherently ductile and are embrittled through contact with air. Machlin and Murray4 hypothesized that a layer of NaCIO3 produced by contact of ozone with NaCl induced embrittlement by acting as a barrier to outward dislocation flow. westwood,' Rosenberg and Cadoff,9 and Bilello and cadoff' have reported surface strengthening of LiF crystals by coating with a magnesium compound and then heat treating for adherence. The major effect of the coat was to inhibit dislocation-slip lines from reaching the specimen surface. westwoods showed microcrack formation and fracture to be caused by slip-band interactions at the surface. The material presented in this paper is an extension of the work reported earlier by Bilello, Rosenberg, and cadoff'6,7 and illustrates the wide range of surface properties and bulk behavior obtainable by use of heat-treated magnesium-diffused surface regions in LiF crystals. EXPERIMENTAL PROCEDURE The LiF single crystals were obtained from the Harshaw Chemical Co. Some batch to batch variation was observed; therefore all specimens for a given test series were cleaved from the same crystal. The typical dimension used was 1 by 0.1 by 0.40 in. Surface damage resulting from cleavage was removed by chemically polishing in a 2 pct NH4OH solution. Each group of specimens was given a vacuum anneal at 700°C for 4 hr to provide a base standard for measuring comparative effects of various surface treatments. To produce the reacted surface zone, the annealed specimens were immersed in a boiling suspension of MgF, in doubly distilled HzO, agitated slbwly for 30 sec, removed, and dried at room temperature. Uniform coatings of MgF, were deposited with a thickness of approximately 5 mils. It should be noted that this technique can be modified for use with crystals which are soluble in water by using boiling absolute alcohol as the dissolving medium. This was found effective for the coating of NaCl with MgF2. The diffused surface zone was obtained by annealing the coated samples at elevated temperatures in a vacuum of lob4 mm Hg. Penetration depth was controlled by varying the annealing time from 1/2 to 28 hr. After heat treatment, the samples were tested for bend strength and hardness. Load was applied by four-point bending in a hard-beam testing jig. Four-point rather than three-point bending was used to provide a wide area of constant stress and to minimize the effect of localized inhomogenities in the specimen. The deflection rate was 8 x min-' and the distance between knife edges was 1/4 in. Load-time curves were obtained from a chart recorder coupled to the machine and converted to resolved shear stress on the shear plane vs deflection, as plotted in the figures. The unstressed portions of the sample outside of the two outer knife edges were used for the microhardness studies. Microhardness measurements were made with a Bergsman tester attached to a Reichert metallograph. All hardness impres-

Jan 1, 1964

By F. W. Brown

In 1942 the Explosives Division investigated electrostatic hazards associated with the manufacture, storage, and use of explosives. A report was issued in 19454/ presenting the data on the spark sensitivities of explosives. In 1948, the apparatus was redesigned and rebuilt to make the routine testing of explosives safer and more convenient. The rebuilt apparatus is described in this re-issue of the former report. Included are details of construction and a list of parts. PRINCIPLES OF METHOD In normal procedures without special precautions, it is possible for static charges to be accumulated on individuals or on ungrounded equipment or structures.5/ Static charges may be produced in many ways, but they are most commonly produced by rubbing or successive contact and separation of unlike surfaces, at least one of which is usually an insulator.

Jan 1, 1953

By Rafael Humberto Mota de Siqueira

A conformação a laser (Laser Beam Forming – LBF) é um processo mecânico sem contato realizado pela introdução de tensões térmicas na superfície de um material com laser, a fim de induzir a deformação plástica. Neste estudo, foram realizadas conformações em chapas de 1,6 mm de espessura, de alumínio de alta resistência, classe AA6013-T4, com uso de um laser de Yb-fibra operando em modo contínuo. A potência do laser foi variada entre 200 e 1000 W e a velocidade entre 3 e 30 mm/s, com o feixe desfocalizado em 5 mm sobre a superfície da chapa. O ângulo de dobramento das chapas variou entre 0,1 e 2,5° por passe, dependendo das condições experimentais. Na condição de maior ângulo, 1000 W e 30 mm/s, a poça de fusão atingiu 0,6 mm de profundidade, porém sem alterar a microestrutura da parte inferior da chapa. Em todas as condições, a dureza se manteve constante em aproximadamente 100 HV, sendo semelhante ao material de base. Para verificar a aplicabilidade do método, foram desempenadas chapas previamente soldadas na configuração T. O método mostrou-se eficiente em corrigir o empenamento de chapas com inclinação de até 5°.

Aug 16, 2017

By W. T. Sampson

Introduction The Kirkland Lake (Ontario) property of Wright-Hargreaves Mines, Limited, - consists of four claims. The two main shear zones or 'breaks' of the Kirkland Lake camp extend through three of these claims, for a distance of approximately 3,500 feet. These claims are on the northeast side of the original lake. The water in this section of the lake has now been replaced with mill tailings. The degree of success of any completed undertaking, especially in the mining industry, reflects the personnel involved. I state with pleasure that the successful deepening of No. 5 winze from 6,400 feet to 7,272 feet was largely due to the co-operation and skilled workmanship of Shaft Captain J. Myelde and his efficient 'leaders'. This winze was sunk at a time when it was most difficult to obtain experienced shaftmen, with the result that the crews did not wholly consist of experienced men (although their desire to learn shaft sinking soon gave good results). This condition added greatly to the responsibilities and duties of those in charge, whose first consideration was for the safety of those engaged in the work, and I take great pride in recording that the entire sinking programme was completed without a lost-time accident. Location of Winze Due to the information obtained through deep diamond-drill holes collared below the 6,000-foot level being of sufficient importance to warrant further exploration, it was decided to deepen the existing No. 5 winze rather than sink another winze. This decision meant that the sinking must be co-ordinated with and proceed simultaneously with operations in the winze, where mining was being carried on between the 3,900-foot and 5,100-foot horizons, inclusive.

Jan 1, 1948

By Jefferson Caponero

The tire is an expressive component of Municipal Solid Waste, manly when its occupied volume is considered. Its treatment by pyrolysis stands for a list of advantages, such as: landfill releasing and a production of a high quality fuel. The exploitation of new natural resources is becoming more difficult each day, basically due to the environmental damages caused by this type of activity. This work presents a study on the thermal behaviour of Brazilian tires using thermogravimetric analysis and differential thermal analysis, in order to optimise the pyrolysis process of tires. Samples of I to 2 mm were investigated at atmospheres of nitrogen, argon, oxygen and mixtures of these gases at temperatures up to 1273K, under heating rates between 1 to 50 Klmin . The results showed that the behaviour of each sample is related to both the atmosphere composition and the heating rate.

Jan 1, 2001

By R. A. L. Drew, G. Mendoza-Suarez, J. Filipi, R. Vintila, J. A. Kozinski

Economics and environmental considerations along with the increasing demand of hydrogen encourage development of novel technologies such as plasma processing of hydrocarbons and thermal cracking of natural gas. Plasma discharges, either in thermal or non-thermal regimes are expected to allow low temperature and fuel flexible on-site hydrogen generation. The main drawback of thermal plasma reformers is the high-energy consumption resulting from high-temperature operation. On the other hand, non-thermal plasma, generated by dielectric barrier discharge (DBD), is able to simulate the chemical reactions employing much lower energies than those required by thermal treatment processes. The non-thermal plasma process allows for instance, a direct conversion of methane into hydrogen and carbon black with no CO2 release. The focus of this research was on the GHG-free method of H2 generation in compact non-thermal plasma reactors using low, medium and high permittivity dielectric ceramics. A stable, non-thermal plasma was generated by placing a dielectric ceramic between two electrodes with a 25 thou gap and applying an alternating current of 1-5kHz and voltages of 4-8kV. In order to ensure energetic efficient plasmas, experiments were conducted to analyze the behaviour of different permittivity ceramics. It was found that the dielectric properties of a ceramic, when used in a DBD reactor, have a strong influence on the discharge characteristics, which in turn influence the power consumption. Higher dielectric constant resulted in higher conversion rates of methane (higher yield of hydrogen and carbon). At the same time, the mechanical properties of the dielectric material, which are closely associated with its processability, influenced its resistance to electron bombardment, as well as thermal and mechanical damage. Therefore a reliable ceramic should have good dielectric properties, in addition to good thermo-mechanical stability.

Jan 1, 2004

By Juan Marcelo Rojas Arango

O refino de grão da estrutura bruta de solidificação da liga Cu-8%Sn com a adição de Zr foi estudado através da análise térmica e da observação da macro e microestrutura. Os resultados macro e microestruturais mostram que a adição de Zr causa a diminuição do tamanho médio de grão em até 90%. A diminuição do super-resfriamento da recalescência e do período da recalescência, medidos nas curvas de resfriamento, estão correlacionados com a diminuição do tamanho médio de grão causado pela crescente adição de Zr, indicando uma possibilidade de controle do tamanho de grão a partir da análise térmica. A análise da microestrutura das amostras em conjunto com a técnica de extração de precipitados por réplica mostra evidências de que o mecanismo de inoculação é a nucleação heterogênea da fase Cu-a sobre as partículas de ZrC formadas no banho líquido a partir das adições de Zr.

Aug 17, 2017

By John F. O'Leary

The paper review the process the minerals industry and the materials revolution. For a long time, Latin América attemps at industrialization have been attempts in part, by need to important some of the many raw materials that industrial nations must have. However, the industrial sistem may be in for some of the many raw materials that drastic changes would increase the mineral self sufficiency of countries that are industrialized. In this way, the materials revolution would be a boom to Latin America, it would reduce some of the serious obstacles to the goals which all Americans seem to share.

Nov 20, 1969

By Gonzalo Mato, Colin Godwin, G. Ditson

"The mid-Cretaceous Seagull batholith intruded Mississippian sedimentary and volcanic rocks and Jurassic(?) granitic and ultramafic rocks within the Omineca Crystalline Belt in the Yuk on Territory near the British Columbia boundary. Leucoerotic fluorine- and boron-rich granites of the batholith exhibit many textural variations from aplite to pegmatite, but are dominated by a coarse-grained seriate unit and a fine-grained porphyritic unit.Four distinctive tin vein occurrences within and near the batholith are described, the most interesting of which is the MC showing of quartz-calcite-chlorite-cassiterite veins in intensely fractured zones of sedimentary and volcanic rocks. Three other showings occur within the batholith:J) the EC showing of quartz-fluorite-cassiterite-sulphide veins with prominent muscovite-illite alteration;2) the DU showing of quartz-hematite-fluorite-sulphide- sulphide-cassiterite with considerable manganese staining and sericitic alteration; and3) the VAL showing of quartz-tourmaline-cassiterite-fluorite-arsenopyrite veins with little associated alteration.Most cassiterite occurrences are within easterly-trending, vertical structures and all occurrences are thought to represent parts of a single system. These mineralogical and physical variations are apparently related to the distance from the upper contact of the batholith.For the Seagull batholith, Rb-Sr isotopic data give a 100±1.4 Ma isochron age that is concordant with the K-Ar model age from biotite of 101±4 Ma. Initial Sr isotopic ratios for the batholith are high at 0.712, indicating an old, sialic crustal source for this pluton. This initial ratio is similar to values for granitic rocks associated with tungsten deposits in the Yukon Territory. The high initial ratio for Sr, the high Si02 content, the high s/I index, the presence of normative corundum. leucogranitic composition and associated lithophile-tungsten mineralization demonstrate that the Seagull batholith is probably an S-type granitic body. This factor is significant to regional exploration jar tin and tungsten in the Canadian Cordillera."

Jan 1, 1983

By Tim Brick, Peter Jewell, Stephen Thompson, Simon Morgan

The $980m (€750m) Dublin Port Tunnel, Europe’s biggest urban highway tunnel project, was opened in December 2006. The culmination of this immense scheme is set to transform the environment, mobility and road safety of Ireland’s capital city. This paper summarizes the key aspects of a project linking both sequential and parallel construction of individual tunnels and describes various approaches to bored, mined and pre-support cut-and-cover tunneling in a wide variety of ground types and depth of cover. Examples of innovative approaches to deal with structural and geotechnical problems while maintaining full operation of both road and rail traffic and the integrity of properties in a dense urban corridor are described.

Jan 1, 2007

By A. C. Fieldner

Much activity is called for in the present period of hightened national effort, and wise direction of such a program must always be conditioned by positive knowledge gained in years of slow and painstaking study and development. Research and technologic investigations on coal by the Bureau of Mines have been described in a series of annual

Jan 1, 1941

By E. W. Felegy

Since 1920, the Bureau of Mines and, other agencies have conducted numerous investigations of methods of communication for use in mines in times of disaster or emergency. The results of these investigations have been reported in various publications (3, 4; 5, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16). In November 1944, the Bureau of Mines resumed the study of emergency underground communications. Until March 1946, the program was directed toward reexamining methods of underground communication that indicated possibilities of success. Since April 1946, the principal interest of this investigation has been in methods of application of radio to communication in mines, low-frequency radio seeming to offer the most promise as a successful method of emergency mine communication. Results achieved in reexamining other methods and in the investigation or the application of low-frequency radio between November 1944 and September 1946 were reported previously in a publication entitled "Some Studies on Emergency Mine Communications".

Jan 1, 1948

By AIME

PROBABLY no greater world traveler has ever been Chairman of one of the Institute's Divisions than Henry Frederick Hebley. To begin with, he was born almost as far away as possible-in Christchurch, New Zealand, Dec. 15, 1893. There he grew up, studying mechanical engineering at the local Seddon Memorial Technical College. Then he went over to Sydney, Australia, for a bit of work before sailing for the U.S.A. in 1915. After a few months as draftsman in a San Francisco office he moved over to Clarkdale, Ariz., in the engineering department of the United Verde copper smelter, which had just gone into operation. But the war was on, and Henry thought he belonged in France with the Canadian Engineers, the United States still remaining aloof from the conflict, and that was the last the copper industry saw of him. After almost two years in France he was wounded, convalesced in England and Canada, and then went back to his native New Zealand to design concrete factory buildings. But soon the United States called again, and this time he landed in Salt Lake City with the Oregon Short Line R.R. Co. Then to Chicago in 1920. where he really got into the coal industry for good, working for the Allen K Garcia Co. on the design and operation of coal mines, beneficiation plants, and combustion equipment; and joining the Institute.

Jan 1, 1946

By E. P. Youngman

Zirconium, formerly distinctly a rare element, is rapidly becom- ing of rather extensive commercial importance. Economic features of the zirconium industry, together with general information regarding the metal and its compounds, are discussed in a separate paper, to which this paper is a supplement. In addition to giving a brief discussion of the four or five de- posits that so far have proved to be commercial sources of the element, this circular summarizes available data (including some hitherto unpub lished material from the files of the Bureau of Mines) upon other occur- rences, including many of scientific interest only, of the two commercial. minerals, zircon and baddeleyite, and also data upon some of the minor minerals, such as eudyalite and cyrtolite, which have attracted addition- al interest in recent years because they are frequently richer in hafnium than the more common zirconium minerals.

Jun 1, 1931