Search Documents

By J. P. F. Charpin

The transport of large boulders in a furrow from a mining area to a nearby pond was considered. The furrow is filled with a mixture of water and soil particles flowing down to the pond at high velocity. Due to operating constraints, the slope of the furrow is reduced progressively. A relationship is derived, relating the slope of the furrow and the composition of the fluid to the maximum size and shape of the transported boulders. The characteristics of the boulders carried all the way down to the pond may then be determined.

Jan 1, 2007

By J. L. Thornton

Introduction The importance of coal in our economy is well established, but it may not .be so generally realized how important a part it plays in our daily life. Select a product - any product - and, if it is made in America, bituminous coal has touched it first. Everywhere we will find coal, derivatives of coal, or functions made possible by coal. Apart from the well known major uses of coal for domestic purposes, coking, utilities, railways, and manufacture of steel and cement, there are over 200,000 products derived from coal, from lipstick colours to nylon products and perfumes. An item of interest is the recent action of the Canadian Government in voting $90,000 for development of coal deposits in Yukon Territory to make coal available to the settlers in that area. The value of this move, in case of some emergency, is very evident. Coal in its several stages of formation as peat, lignite, sub-bituminous, bituminous, semi-bituminous, semi-anthracite, and anthracite, has been used for centuries. Coal, as such, was not very well known to the ancients. First reference to "magic stone', or coal, was in 371 BC by Theophrastus, a pupil of Aristotle. This substance was said to burn like wood coal or charcoal and was used by the smiths. The first record we have in modern times was in 852 AD, when sea coal was gathered by the cowled monks of Durham, in Britain, and even at that time a major problem was transportation. Our first record of coal in this continent was near Richmond, Virginia, in 1700. Commercial mining was not under way, however, until 1750. The anthracite fields (presumably in Pennsylvania) were opened in 1793. Even so, there was no extensive mining until about the year 1820. The famous Pocahontas coalfields were opened in 1883. The earliest record of coal mining in Canada is about 1746.

Jan 1, 1950

By Frederic Benard

PRIOR to 1936, the Ontario Refining Co. received all incoming blister copper from The International Nickel Company's smelter in the usual form of 460-lb. cakes, or slabs. These were received in open cars in lots of 250 pieces. At the refinery the cakes were unloaded onto narrow-gauge cars, for convenient handling and pickup by charging cranes. In March 1936, an investigation was started on the feasibility of transferring converter copper in the molten state from the smelter to the refinery anode furnaces, a distance of 1 ¼ miles. Although common in steel practice, the transportation of blister copper in this form had not previously been attempted and a preliminary study of the various factors involved was therefore necessary. For this purpose, a series of experiments was made in which molten copper, removed at different stages during the furnace cycle, was held in a small portable holding furnace. This vessel was essentially a refractory-lined steel cylinder provided with ports for filling and emptying, heated by an oil burner. Dimensions of the steel shell were 3 ft. 10 in. diameter by 7 ft. 3 in. long, and thickness of refractories depended on the design and combination used for the particular experiment. The vessel was filled with approximately 2 ½ tons of copper at a predetermined temperature, the lining having been preheated to a definite point by means of an oil burner. All openings were well luted and temperature readings were made every 15 min. by means of an immersion-type thermocouple. In this manner the rate of heat loss resulting with different refractory design could be developed. The ratio of exterior surface to weight of metal was taken into consideration in comparing the experimental results with what might be expected for a full-sized unit, and observations were also made on type and degree of slag accretion. It was not possible to get as much information on this latter point as desirable, but all evidence showed that the problem would be control of slag build-up rather than attack on refractories. From the information derived, and in consultation with the engineering staff of the supplying company, an order was placed for the first

Jan 1, 1938

By Frederic Benard

PRIOR to 1936, the Ontario Refining Co. received all incoming blister copper from The International Nickel Company's smelter in the usual form of 460-lb. cakes, or slabs. These were received in open cars in lots of 250 pieces. At the refinery the cakes were unloaded onto narrow-gauge cars, for convenient handling and pickup by charging cranes. In March 1936, an investigation was started on the feasibility of trans-ferring converter copper in the molten state from the smelter to the refinery anode furnaces, a distance of 114 miles. Although common in steel practice, the transportation of blister copper in this form had not previously been attempted and a preliminary study of the various factors involved was therefore necessary. For this purpose, a series of experiments was made in which molten copper, removed at different stages during the furnace cycle, was held in a small portable holding furnace. This vessel was essentially a refractory-lined steel cylinder provided with ports for filling and emptying, heated by an oil burner. Dimensions of the steel shell were 3 ft. 10 in. diameter by 7 ft. 3 in. long, and thickness of refractories depended oil the design and combination used for the particular experiment. The vessel was filled with approximately 2 ½ tons of copper at a predetermined temperature, the lining having been preheated to a definite point by means of an oil burner. All openings were well luted and temperature readings were made every 15 min. by means of an immersion-type thermocouple. In this manner the rate of heat loss resulting with different refractory design could be developed. The ratio of exterior surface to weight of metal was taken into consideration in comparing the experimental results with what might be expected for a full-sized unit, and observations were also made on type and degree of slag accretion. It was not possible to get as much information on this latter point as desirable, but all evidence showed that the problem would be control of slag build-up rather than attack oil refractories.

Jan 1, 1938

By Emilie Williams

Introduction Mouska Mine, Doyon Division site Background and timeline Obstacles to standard paste delivery system Components of Mouska paste system Technical considerations Operational considerations Mouska Mine Underground gold mine 30 km east of Rouyn-Noranda, Quebec Part of Doyon Division, 100% owned by IAMGold Commercial production since 1991 Cumulative production over 850,000 oz Conventional mining until 2009 485 m shaft from surface 560 m internal shaft 500 tpd (ore and waste) Off-site milling Approximately 150 employees

Oct 1, 2010

By Warren E. Wilson

THE transportation of solids in pipe lines is a matter of deep concern in many fields of engineering. Much experimental and theoretical work has been done in an effort to devise means of designing pipe lines that will satisfactorily transport given solid loads, but there remain many unanswered questions in this field. The present discussion will be confined to a rather narrow portion of this field and will endeavor to point out certain factors that may well be considered when comparing the relative economy of various installations. The data have been presented previously but a new interpretation was prompted by a suggestion in a paper by Professor O'Brien,1 of the University of California, that the friction work per pound of dry material should be considered in determining the relative efficiency of various installations. This method of considering relative economy in various pipe lines leads to some rather unexpected conclusions, especially with reference to the economy of large pipe sizes. A previous suggestion by the writer3 concerning the economy of a rather peculiar type of installation is strengthened. It is not believed that the considerations set forth herein apply directly in the case of dredge lines, where economy is largely a matter of a high rate of pumping in order to reduce the unit overhead charge. However, it is believed that some value may be gained from these considerations in cases involving the disposal of a fixed amount of solids per unit time with a minimum expenditure of energy and at a low cost for replacement of worn pipes. Such situations are not uncommon in the disposal of mill tailings and the disposal of solids deposited from irrigation waters. It was found that data leading to general conclusions for various pipe sizes were not available but certain definite trends are indicated and methods of analyzing available data are presented in the hope that they may be of assistance in preparing engineering estimates on designs of pipe lines of the type described above. ENERGY. REQUIREMENTS Carrying out the idea contained in Professor O'Brien's paper concerning the method of computing energy required to transport solids, the following analysis leads to some rather interesting conclusions. Let us represent: [Solids load in terms of mass per unit time by W Ratio of mass of suspended solids to total mass of mixture flowing by p Volume rate of flow of mixture by Q Length of pipe by L Slope of energy grade line by s Mass per unit volume of solids by m, Mass per unit volume of liquid by ml Mass per unit volume of mixture by m,,, We then have as an expression for the solids load: W = pQm¬] The work done per unit mass, P, on the mixture to move it along the pipe the

Jan 1, 1945

By W. Jack Wilkes, Gilbert L. Butler

TRANSPORTATION TUNNELING The use of tunnels for transportation, namely rapid rail transit systems and highways is on the increase. How much that increase might be through the 1980's is the question that is discussed in this paper. In 1975, there were 218 route miles of subway tunnels for rapid rail transit and 154 lane-miles of highway tunnel. From the viewpoint of many transportation planners and designers, the tunnel is one of the tools which may be used to by-pass many types of obstacles: a mountain, a body of water, or a Central Business District (CBD). Therefore, the transportation tunnel is a rural as well as an urban solution with major emphasis on the latter because of the current transportation needs of our cities. In the case of rural locations, tunnels are usually constructed through mountains in order to eliminate miles of steep grades and dangerous curves, such as the Eisenhower Tunnel which cuts through the Continental Divide in Colorado along 1-70 and saves 10 miles and 40 minutes of driving time. Tunnels also provide an excellent transportation link across bodies of water in order not to interfere with shipping lanes. The Chesapeake Bay Tunnel and Bay Tubes of the BART system are excellent examples of this type of tunnel.

Jan 1, 1976

By J. W. Buch

IN THE FIELD of track haulage, interest has seemed to center on the question of larger mine cars both for handling material from loading point to shaft bottom or surface, and for shuttle service. Saving of time in car changing is obvious if larger cars are used. In addition, shorter trips result where car transportation is from face to opening without transfer. This also brings about side-track and equipment savings. Track shuttle service, using large automatic-dump cars (10 tons) between loading machines and trip loading point, has been a satisfactory solution for the operator who mechanizes a working mine regularly equipped with a large number of small mine cars. This development in track shuttle haulage, has made track installation and maintenance increasingly important, requiring closer supervision.

Jan 1, 1942

By John W. Buch

IN my review a year ago I pointed out that a small coal-mining companies as well as large had decided that the so called ?central shop? was a benefit. These central shops replaced in a large measure the commercial shops operated by those who have no direct connection with production of cod. Central shops in this time of salvage and major repairs have proved their worth. In addition, many of the larger companies had in their central shops equipment available for the production of many thousands of parts for our vast war machine and, as subcontractors, are doing this type of work. This is a real contribution to the war endeavor. Lack of new supplies has resulted in exhaustion of those stocks formerly stored or hidden in underground shanties. This means that the small stock of repair parts likely LO be available to any mine

Jan 1, 1943

By Antonio Fernández, Javier Cáceres, Enrique Ramírez, Camila Yepez

El sector minero es una de las pocas industrias que depende de los precios de mercado para producir. Por lo cual, mantener ventaja competitiva y garantizar la eficacia del proceso para alcanzar las metas propuestas por la empresa minera representan un desafío constante. Esta investigación tecnológica tiene como objetivo maximizar la eficacia en los procesos de transporte y perforación manteniendo los costos más bajos en su proceso productivo. La investigación presentó dos desafíos durante la etapa de prueba que fueron la especialización del personal y modificación progresiva de los equipos para cada actividad específica.

Sep 30, 2022

By Einar Carreño

El artículo evalúa 4 alternativas para el transporte de la mezcla para concreto shotcrete en una operación minera subterránea (Volcan): 1) con planta en el interior de la mina, 2) mezcla enviada por una red tuberías de acero a tubo lleno, 3) mezcla enviada a impacto por un tubo de acero vertical y 4) con un sistema mixto de transporte masivo de relleno cementado. Se evalúan con detalla ventajas y desventajas de cada alternativa y se ofrecen recomendaciones para optimizar el proceso reduciendo tiempo y costos.

Sep 20, 2019

By Eberhard Rother

El presente texto describe el transporte fluído de materiales sólidos, su clasificación, características del flujo de mezclas heterogéneas, los experimentos del transporte hidráulico de fluidos y los resultados de estos en la ingeniería.

Sep 1, 1960

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 Niels Kofoed

Upon completion of the 6,200 m (20,340 lineal ft; lft) North Tunnel drive for the Portland East Side Combined Sewer Overflow (CSO) Tunnel project in Portland, OR, the slurry tunnel boring machine (TBM) had to be returned from the Port Center shaft at Swan Island to the Opera shaft at the main mining site for the 2,700 m (8,860 lft) South Tunnel drive. At the Port Center shaft, the main 513-t (565-st) TBM and TBM tailshield were hoisted out of the shaft in two pieces using four 200-t (220-st) strand jacks mounted on a 635-t (700-st) hydraulic boom gantry system supported by Emmert International?s custom gantry tracks designed to span the shaft. After lifting the TBM components out of the shaft, the gantry system loaded the TBM components onto two Goldhofer platform trailers, which then transported the TBM and tailshield to a barge using a roll-on/roll-off method.

Jan 1, 2011

By W. A. Haley

Wheel loaders became important bulk materials handling tools in the early fifties. As they grew in stature, productivity, reliability, and acceptance, the demand for larger, more rugged machines evolved. In the early sixties, the introduction of a 6-yard model by a major equipment manufacturer led quickly to widespread experimenting and rapid worldwide acceptance in loading blasted rock in stone quarries and smaller metal mines. As the wheel loaders grew in popularity for shot rock loading, larger models, 12- to 15-yard size were developed and saw widespread use by 1970. In the past 20 years, at most quarries and small to medium size mines, most cable operated power shovels have been replaced by large wheel loaders and more recently, hydraulic excavators as the primary loading tool. Wheel loaders larger than the 15-yard class are not used widely. Until about 1970, very few overburden haulage trucks were used in domestic coal mines. About that time, many states started enforcing stringent mine relcamation regulations and in 1977, even more stringent federal legislation was passed. These controls brought about drastic changes in coal surface mining methods in the mountainous areas of Appalachia, in smaller midwestern mines and in the large mines of the western states. Basically, simple material casting methods were replaced at most eastern mines by "haul-back" and "mountain top mining" methods using controlled placement of overburden as it is removed from the coal. These methods dictated much more extensive use of loaders/ shovels and trucks to the point that most coal mining in those areas is now by loader/shovel trucks methods. And those areas have become the home of the country's largest population of large wheel loaders and trucks in the 35- to 85-ton size class with a trend to even larger trucks and shovels. To maintain equal production or provide for growth, the new methods have caused a sharp increase in machine intensity to the extent that at some mines, up to three times as many machines were required to mine a million tons of coal in the late seventies as compared to the machine needs in the sixties. Mining costs and coal prices also took a big jump in the mid-seventies, paralleling the drastic price increases in oil and other forms of energy.

Jan 1, 1984

By Shimi Tzobery, John E. Shamma, Samuel Swartz, Gary B. Hemphill

The trapezoidal tapered ring method has made significant progress in recent years for shielded-TBM projects, excavating tunnels with high overburden, strict water tightness criteria, and multiple curve alignments. The selection of compatible tapered rings is critical for successful advancement of the tunnel, assuring efficient installation of rings, as well as prevention of ring damage and excessive leakage. Using experience from the Arrowhead Tunnels Project, this paper describes guidelines for ring selection in tunnel curves, geometric analyses that comply with criteria principals, and provides techniques developed to determine the appropriate relative key position.

Jan 1, 2005

By Elena Kalinin Toss

Inúmeras indústrias necessitam de sistemas de tratamento de água que favoreçam o processo de descarte de seus efluentes, além do aproveitamento do reuso de água. A mineração e siderurgia podem apresentar rejeitos com metais, que necessitam de tratamentos econômicos e sustentáveis. A biossorção é um exemplo de técnica que vem ganhando interesse em diversas áreas da pesquisa. O objetivo do estudo foi avaliar a porcentagem de remoção de íons de níquel de uma solução monoelementar de cloreto de níquel II (NiCl2+) em pH 2, 4 e 6. Para isso, utilizou-se um sistema de batelada, e 1g de consórcio bacteriano liofilizado (sem ser autoclavado) isolado de amostra de terra. Os resultados indicaram que a eficiência da biossorção foi maior para o pH 6, e que o consórcio bacteriano foi eficiente na remoção de íons de Ni2+.

Oct 30, 2017

By Jayna Kátia Dionisio dos Santos

Os materiais compósitos tornaram-se ao longo dos últimos anos, essenciais ao surgimento de novas tecnologias. Para tanto, é imprescindível que alguns cuidados sejam considerados ao desenvolver estes materiais, como o uso do processo de fabricação adequado e a aderência fibra/matriz, sendo este último um fator preponderante na resistência mecânica final do produto. Também se torna cada vez mais necessário o desenvolvimento de materiais com capacidade de utilização ecologicamente correta. Diante disso, foi fabricado um compósito parcialmente ecológico, utilizando como reforço um tecido de sisal, e como matriz resina poliéster. Ainda, buscando a melhoria da aderência fibra/matriz foi efetuado um tratamento com Hidróxido de sódio (NaOH) a uma concentração de 3% no reforço de sisal. Para a caracterização mecânica do compósito, foram realizados ensaios de tração uniaxial nas fibras tratadas e não tratadas, bem como nas lâminas que utilizaram estas fibras como reforço, mediante a norma ASTM 3039. Quanto a esta propriedade mecânica, foi observado que o tratamento químico superficial diminui expressivamente a resistência à tração da fibra e, em contrapartida, aumentou a resistência do compósito polimérico quando comparado ao que utilizou fibra não tratada, confirmando assim o efeito positivo do tratamento na superfície do reforço de fibra natural.

Aug 8, 2018

By Saulo Brinco Diniz

O presente trabalho buscou explorar a influência de um tratamento térmico de ressolubilização, realizados com distintos tempos (70, 80 e 90 minutos) a uma temperatura de 510ºC, na microestrutura e na dureza de uma liga de alumínio 7475- T7351. Para verificar a influência destes tratamentos térmicos foram utilizados um durômetro (fabricante EMCOTEST, modelo Duravision 300) e um microscópio óptico (Olympus, modelo GX51). Após os resultados obtidos, pode-se evidenciar que a liga de alumínio em estudo sofre um envelhecimento natural (a temperatura ambiente), e dentre os tempos de encharque estudados, 70 minutos é o tempo que possivelmente obtém-se a maior ressolubilização dos precipitados.

Aug 17, 2017

By Keli Vanessa Salvador Damin

Este trabalho apresenta uma nova abordagem sobre o emprego sequencial dos tratamentos termoquímicos de superfície utilizando a tecnologia de plasma. No trabalho são avaliados tratamentos de superfície, individuais e sequenciais, de nitretação/cementação. Os tratamentos foram realizados no campo ferrítico com o objetivo de manter as tolerâncias dimensionais. Amostras de aços AISI 1005 foram tratadas em descarga luminescente anormal sendo realizados ciclos únicos de cementação e nitretação e também ciclos conjuntos de nitretação + cementação. Todos os tratamentos foram realizados a 500°C com um tempo de patamar de 3 horas para cada tratamento. A composição da mistura gasosa variou de acordo com o tratamento: nitretação - 5%N2 + 95%H2 ou 3%N2 + 97%H2; cementação - 5%CH4 + 95%H2. A caracterização microestrutural das amostras foi realizada por microscopia óptica e MEV além de difração de raios-X. Análises de microdureza também foram realizadas. As analises de raios-X mostraram que ocorre a estabilização de uma camada de cementita nos tratamentos de cementação. Nas amostras nitretadas em atmosfera contendo 5% de N2 foi observada a presença de camada de compostos. Já em atmosferas contendo 3% de N2 não houve a formação da camada de compostos. A maior profundidade de endurecimento foi obtida para a amostra nitretada + cementada.

Aug 16, 2017