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By Michael H. Wysockey

The load test program for the pile foundation at Soldier Field included static and dynamic load tests at four locations around the site. The dynamic tests were run with no knowledge of the static results, and comparison between the two is very good. It was necessary to use a special testing hammer (not the production hammer) to demonstrate capacity with dynamic testing. Over 90% of the piles were HP14x89 with a design load of 230 tons (18 ksi). The load tests showed a capacity in excess of 590 tons for all tests where sufficient set up time was allowed. The remainder of the piles were mostly HP 12x53 with a design load of 100 tons (13 ksi). The measured capacity of these piles was typically about 250 tons. One experimental HP12×74 pile with a nominal yield of 65 ksi held 730 tons (67 ksi) before failing.

Jan 1, 2002

This paper is concerned with the blasting of rock in mining. The most common purpose of blasting rock is to cast it or to disrupt its structure sufficiently for effective digging and subsequent removal.

Jan 1, 1991

By Gualberto Salas Torrelly

La voladura cerca al perímetro del Tajo en Cerro Verde, origina problemas de estabilidad en las paredes finales. En ese sentido, con la finalidad de mejorar la estabilidad de los taludes y la integridad de las paredes finales, se utiliza la técnica de precorte para minimizar los daños que pueden ocurrir detrás de la zona de voladura de producción. Por ello, el presente texto describe la aplicación de dicha técnica al Tajo Cerro Verde, donde se logra recuperar más mineral y se deja de mover desmonte al tener taludes más estables.

Sep 14, 2009

By Héctor Ugarte y Chamorro

El presento trabajo revisa las diversas medidas preventivas de seguridad minera que se dieron en el periodo colonial peruano. Durante la colonia, la deplorable situación económica y social del indio, conlleva una reacción de defensa humanitaria por parte de los frailes a través de leyes en favor de los indios. Posteriormente en 1551, el virrey La Gasca elaboró una serie de medidas como "Las leyes de indias", "Las ordenanzas de nuevos descubrimientos y poblaciones",entre otros, que protegian a los indios. En 1783 se dictaron "Las Ordenanzas de minería" para la nueva España y fue el virrey Francisco de Toledo, el primero en dictaminar la construcción de pozos y puentes en lugares convenientes, castigando a los infractores. En su Ordenanza II, refiere el caso de las minas de Potosí y ordena no desbaratar puentes ni pilares para evitar riesgos inútiles, mientras que su Ordenanza III dispone la regulación de las escaleras seguras de scrinejas. Asimismo prohibió el trabajo de menores de edad y el "pallaqueo" de mujeres en la mina. En cuanto a la salud ocupacional refiere, el virrrey Toledo dispuso la distancia entre el humo generado por el plomo y zinc, y los trabajadores, asi como su indemnización durante tres meses. Don Juan Solórzano fue otro de los partidarios que ordenó la eliminación del régimen de "obrajes"puesto que era excesivo para la salud de los indios. Las "Ordenanzas de la minería" rescatan también la valía de los operadores mineros, así como las "Declaraciones de Escobedo", donde se estableció la ventilación en el lugar a explotar y la supervisión adecuada de parte de un guardaminas calificado por algú facultativo de la minería. Tanto estas ordenanzas como otras disposiciones tuvieron su base en el Derecho romano. Finalmente, en los inicios de la República, el químico y primer director general de minería, Mariano Eduardo de Rivero y Ustaríz inspeccionó los centros mineros de Puno y Huancavelica, y dictaminó un decreto como medidas de protección para los obreros expuestos a enfermedades y accidentes ocasionados por el mercurio. Dicho decreto está compuesto por 8 considerandos y 4 artículos y apela a los conciudadanos a cumplir las normas en beneficio, salud y seguridad de los trabajadores mineros.

Jul 20, 1959

By Claudia Monreal L., Dafne Herreros

"The Geological Modeling is the undisputed point of split of any type of mining method, the effect that the vision and experience of the geologists is propagated trough the development of the project and is an important part of the final success. The collection of information is taken in stages. In earlier stages uses the greater part of the budget and the strategy to store and manage this data collection, as its performing will define the destiny of the deposit and of the business. With this background the geology and its modeling receive great attention from the industry and care providers being a fertile field in research and innovation. "

Sep 1, 2017

By W. Wittke

SUMMARY: Geotechnical problems often lead to an increase of construction time and costs for large highway and railway projects. Some reasons, which have led to failures and thus to a delay of construction works as well as to increasing costs, are demonstrated by means of case histories, in which the author was involved as expert or planner. Proposals are made how to identify the reasons and to avoid repetitions. ZUSAMMENFASSUNG: Bei Großprojekten der Verkehrsinfrastruktur stehen häufig geotechnische Aufgabenstellungen im Vordergrund. Wegen geotechnischer Probleme kam und kommt es häufig zu Termin- und Kostenüberschreitungen. Anhand einiger Beispiele, bei denen der Autor als Gutachter und Planer beteiligt war, wird gezeigt, welche Ursachen zu Schadensfällen und damit auch zu Termin- und Kostenüberschreitungen geführt haben. Es werden Hinweise und Anregungen gegeben, wie die Ursachen erkannt und Wiederholungen von Schadensfällen vermieden werden können. RÉSUMÉ: À grands projets de l'infrastructure de la circulation, souvent des tâches géotechniques sont au premier plan. Par suite de problèmes géotechniques, souvent des dates et frais ont été dépassés. Au moyen de quelques exemples, à lesquels l'auteur participait comme expert et planificateur, les causes sont mises en vue qui menaient à des cas de dommage et par cela aussi à des dépassements de dates et frais. Des indications et suggestions sont données pour s'apercevoir des causes et éviter des répétitions de cas de dommages.

Jan 1, 2003

By Thomas D. Kaufmann

Introduction What drives the price of gold? Supply and demand, of course. But in ways far different from the forces that drive the prices of other major metals, such as steel, aluminum, and copper. Gold, in fact, is one of the few commodities where both buyers and sellers are happy when the price goes up. Current production, production costs, and variations in production have little influence on its price. Gold inventories are so tremendous that current production has small impact on the amounts available to the market at any time. Worldwide gold inventory and production The world's inventories seem to be between 78 and 98 kt (2.5 and 3 billion oz). Since biblical times, the gold miners of the world have produced about 98 kt (3 billion oz), mostly in this century. Only small amounts have been thrown away and most of it - more than 78 kt (2.5 billion oz) - remain in bullion, coins, or jewelry. About 40% is held by central banks and other governmental authorities, 30% by private individuals as bullion or coins, and about 30% as jewelry. Except for some of the jewelry and the few industrial applications, this inventory is constantly available in marketable form at a price. By comparison, gold production is indeed small. The US Bureau of Mines estimates that the world produced 1.5 kt (50 million oz) of gold in 1986. Consequently, production increased world inventories by only 2%. Variations in production have a negligible or very short-term effect on the supply and, consequently, on the markets for gold. Although South Africa mines about 40% to 50% of the world's annual production, continuing labor strife there does not seem to have ruffled gold prices. Determining gold's price Gold prices, however, do determine cutoff grades in the mines and, thus, do influence production. Nonetheless, changes in production have little impact on the inventory supply. Consequently, it has small influence on the price of gold on the market. With a fairly stable supply, price changes are driven by changes in its demand. Unlike other metals, very little of the demand for gold comes from industry. Dental, electronic, and other industrial uses for gold consume less than 46.6 t/a (1.5 million oz per year). It would be safe to assume that such uses are less than 124 t/a (4 million oz per year) for the entire world. Variations in the 124 t (4 million oz), compared to a supply of 78 kt (2.5 billion oz) of supply can have only a negligible effect. Production net of industrial uses adds perhaps 1% annually to world inventories. This could, in time, affect markets. The increase, however, is mostly absorbed by population growth - more people wanting to own gold - and by gold being put in more attractive forms, such as coins. As an ancient Lydian king discovered, minting bullion permits

Jan 9, 1987

By C. Van der Veen

The use of the quasi static (Dutch) Cone Penetration Test (CPT) is described as a tool to predetermine the ultimate bearing capacity of the pile point. An analysis is given why a purely theoritical approach does not meet with success. A practical method is explained of extrapolating the cone resistance to predict the pile point resistance. The method has been calibrated against the result of 32 selected high standard loading tests on pile points in the Netherlands.

Jan 1, 1989

By Iván Zevallos

"La mina de talco localizada en el estado de Río Grande del Sur (Brasil) fue explotada hasta agotar sus reservas. En ese sentido, para descartar la existencia de algún cuerpo del mismo mineral en las proximidades se propuso efectuar una prospección magnética terrestre. La asociación del talco con esquistos magnesianos y serpentinitas confiere validez al levantamiento geofísico, debido a la alteración de los esquistos que los torna ferromagnéticos, de forma que se determina que el yacimiento fue explotado. En ese sentido, el presente texto describe el levantamiento magnetométrico como método magnético para determinar el cierre de una mina de talco como importante precedente para los exploradores de yacimientos de minerales no-metálicos."

Dec 1, 2016

Due to highly competitive international coal markets, Stockton mine is bound to produce very high quality coals consistently if it is to maintain and expand its market share. The nature of the deposit is such that coals from various source pits are blended in differing proportions to meet the various coal quality specifications of the customer. The complexity arises due to quality variation within the seam both horizontally and vertically and the fact that up to six different products with completely different quality specifications may have to be produced. With increasing demand for this rare product and with CoalCorp eager to meet this demand comes the requirement for computer methods to handle this highly complex problem of both modelling and scheduling.

Jan 1, 1989

By H. Warren Newcomen

The southwest wall of the Lornex Pit at the Highland Valley Copper mine has been experiencing slope displacements since 1978. Measures to manage the displacements on previous pushbacks have included stepping out, scheduling pushbacks to unload the crest of unstable areas, slope dewatering and mining with intensive slope monitoring. The final pushback on this wall is currently being mined and substantial modifications to the slope geometry could prove to be uneconomic. As a result, a campaign of surface water collection and diversion, horizontal drainhole drilling and deep well drilling is currently underway to maintain an acceptable degree of stability to the end of mine life. The various factors contributing to instability, including engineering geologic controls, rock mass strength, and surface and groundwater hydrology are presented. Movement trends, displacement magnitudes and stability analyses results are also discussed.

May 1, 2002

The point of the anode effect on carbon anodes of dcfincd surface area. during electrolytic decomposition of alumina dissolved in molten fluorides. has been determined from current-voltage curves. The reproducibility and accuracy was found to be better for cell voltage than anode current density. Results have been obtained for the effect of alumina concentration temperature and carbon type. The point of the anode effect was strongly dependent on both the alumina concentration and the carbon type. For high alumina concentrations it has been found that the anode effect approaches reversibility. From these results it is concluded that co-evolution of CO, and CF. occurs prior to the onset of the anode effect. The anode effect results when the CF, content becomes sufficiently high for the melt not to wet the electrode surface and is maintained because of the slow desorption of CF, and the high electrode potential that results.

Jan 1, 1967

By L. Harris

Los finos de coque son materiales que se producen en toda planta de gas y coque y que no pueden ser usados directamente en los hornos metalúrgicos debido que sus propiedades físicas y quimicas ison ndeseables. En este sentido, los finos de coque se producen en altos hornos de fierro y plomo, donde una capa de carbón sin aglomerar y parcialmente coquificado, permanece en la parte superior de la carga y es durante esta descarga que se separa del coque grueso. Sin embargo, el coque descargado es muy grande para el horno y debe reducirse a un tamaño pequeño. Por tanto, el texto señala que para que el coque llegue a los hornos debe contener más de 20% de finos y en el caso de los hornos de plomo, es necesario que se separe de los finos debido a que puede generar un sofocamiento en el rendimiento de los hornos. Así también, describe la operación de la planta de coque en La Oroya, como las características deseadas del coque.

Nov 20, 1967

By W. J. Mahoney

A good quality assurance program at a coal mine or power plant is accurate, timely and consistent. The quality analysis is accurate due to a complete sampling of the coal stream loaded into the unit train. The sample analysis is accurate because standardized testing procedures are applied. Once an analysis is completed, the results must be communicated to the electric utility in a timely manner. The electric utility needs the results to better manage the coal inventory at its power plants. A quality assurance program can also help a mine deliver a consistent product to a utility's power plants. The importance of accuracy, timeliness and consistency are based on major changes that are taking place in the electric utility industry.

Jan 1, 1994

By Luciano Prieto A

La presente investigación refiere el patron de mineralización en Toquepala a través de un método de trabajo estadístico, el cual dispone de un valor promedio y representativo de un conjunto de valores, constituyéndose en sí mismo el punto de partida para hacer apreciaciones de tipo estadístico. Asimismo se describe la geología general, la mineralización por los tipos de roca, las zonas de mineralización y un estudio de la estadística del minado que comprende las reservas minadas de 1975 y 1976, encontrándose que el 68% de la producción mineral fue hecha de brechas y pórfido de dacita y en el que aproximadamente el 60% de la reserva actual está constituida por estas dos mismas unidades litológicas.

Nov 20, 1978

By Richard L. Sanford

This report summarizes the results of an update on a previous Bureau of Mines grant (G0264026), and includes 5 additional years of computer pro-gram development. The directory includes a sampling of computer usage in operating and manufacturing companies, consulting firms, computer companies, research organizations, universities, and various governmental agencies. References to computer applications throughout the industry are presented as well as comments on program availability. The work effort on the updated directory concentrated on programs that are available to the public and are well documented.

Jan 1, 1982

By Ihor A. Kunasz

Lithium minerals occur predominantly in pegmatites that contain mineral assemblages derived from the crystallization of post- magmatic fluids or from the metasomatic action of residual peg- matitic fluids. They have been the traditional sources of raw material for ceramic and chemical industries. With the discovery of the Searles Lake deposits, brines became new sources of lithium, and, today, two brine deposits satisfy nearly one-half of the free world demand for lithium chemicals. Indeed, lithium production from pegmatites has been superseded by brines sources. In the United States, the brines of Clayton Valley, NV, have been exploited since 1964 by Cyprus Foote Mineral Company, a subsidiary of Cyprus Minerals Company. In Chile, Sociedad Chilena de Litio Ltda., an affiliate of Cyprus Minerals Company, is now producing lithium carbonate from the brines of the Salar de Atacama. Recently identified brine deposits suggest that these may well become the prime sources of lithium chemicals. In Bolivia, the government is negotiating the rights to exploit the brines of the Salar de Uyuni. The Salar del Hombre Muerto in Argentina is being evaluated as a future center of chemical production. The brines of the Great Salt Lake of Utah, the Smackover Formation, and the Imperial Valley geothermal field have been defined as important resources of lithium. In Tibet, high concentrations of lithium have been reported in several saline lakes. In the People's Republic of China, lithium may be produced from the brines of the Dabusan playa in the Qinghai Basin. The 1950s saw a great number of lithium companies develop. However, following the termination of the Atomic Energy Commission purchase program in 1959, several companies, such as Maywood Chemical Co., American Lithium Chemicals, and Quebec Lithium Corp., were forced to close their operations. Nevertheless, with the development of new applications in glass ceramics, air conditioning systems, synthetic rubber, and metallurgy (aluminumpotlines), the lithium industry grew steadily. With the potential application of lithium metal in batteries, nuclear reactors, and fuel cells, a steady growth can be foreseen. New products and new applications are likely to stimulate exploration for expanded reserves as well as the search for new sources from which lithium could be extracted economically. Presently identified reserves and production capacity are sufficient to satisfy the conventional market growth of lithium.

Jan 1, 1994

By Juan Carlos Ramírez Larizbeascoa

El presente texto revisa el análisis económico realizado durante los años 1978 y 1986 en las minas de tajo abierto como Cuajone, Toquepala. Así, inicialmente se desarrolló el sistema de cortes concéntricos y bloques. Posteriormente en 1983 y 1984 el método fue adaptado por Thomas. Loose, quien desarrolló el sistema de informática y probó los modelos matemáticos de costo por nivel. Finalmente entre los años 1985 y 1986, el método se aplicó en la evaluación y optimización del método Cuajone donde se consideró los ángulos de talud de la mina, ingresos por uno o varios metales que se explotan, los egresos generados por las operaciones involucradas en la explotación, la ley de corte y la inclusión de parámetros operacionales en la mina.

Nov 24, 1986

By Cristhian Vía

El artículo detalla una experiencia de implementación de microequipos trackless para el minado de vetas angostas, orientada a mantener anchos de minado económicamente factibles, rentables y seguros y a reducir significativamente la sobredilución. Se explica el diseño geomecánico para dimensionar aberturas y paneles, y se describe la estrategia de minado en cada operación unitaria tanto como los parámetros de control. Como resultado, se reportaron mejoras en todo el proceso de minado y se redujeron a cero de los accidentes por caída de rocas. Se perfeccionaron los indicadores de seguridad de la unidad, se redujo la sobredilución de 30 a 10%, y el costo de minado disminuyó de 34.17 $/Ton a 20.63 $/Ton.

Dec 31, 2020

By H. Willenberg, J. S. Coggan

ABSTRACT: Although individually both continuum and discontinuum numerical analyses provide useful means to analyze rock slope stability problems, complex failures typically involve mechanisms related to both existing discontinuities (i.e. discontinuum) and deformation and brittle fracture of intact rock (i.e. continuum). One such example is the 1991 Randa rockslide in the southwestern Swiss Alps, where failure involved several complex mechanisms, which require the consideration of progressive failure and rock mass strength degradation. This paper presents results from a series of hybrid finite-/discrete-element models directed towards the explicit modelling of brittle fracturing in natural rock slopes, enabling the modelling of progressive failure, from initiation, through to the development of catastrophic failure, transport and deposition. RÉSUMÉ: Si les modélisations numériques de type continu ou discontinu fournissent des outils utiles pour l’analyse de problèmes de stabilité de pentes rocheuses, elles montrent de sérieuses limitations lorsque des mécanismes de rupture complexes impliquent des processus liés autant aux discontinuités préexistantes qu’au développement progressif de nouvelles fractures. Ceci se retrouve typiquement dans l’exemple de l’éboulement de 1991 à Randa dans les Alpes suisses du sud-ouest, où la rupture a impliqué plusieurs mécanismes complexes nécessitant la prise en considération de la fracturation progressive ainsi que de la dégradation de la résistance des masses rocheuses. Cet article présente des résultats provisoires d'une série de modèles hybrides orientés vers la modélisation explicite de la fracturation de pentes naturelles, permettant la modélisation de fractures progressive de leur initiation jusqu’à leur développement, leur rupture catastrophique, leur transport et leur déposition. ZUSAMMENFASSUNG: Obwohl numerische Kontinuum- und Diskontinuum-Berechnungen einzeln nützliche Ergebnisse zur Stabilitätsanalyse von Felshängen liefern, sind komplexe Felsrutschungen typischerweise mit Mechanismen verbunden, die sowohl durch bestehende Trennflächen (s.a. Diskontinuum-Ansatz) als auch durch die Deformation und das Versagen intakter Felsbereiche (s.a. Kontinuum-Ansatz) bedingt werden. Ein Beispiel für einen solchen Sachverhalt ist der Bergsturz von Randa 1991 im südwestlichen Teil der Schweizer Alpen, bei dem die Rutschung mehrere komplexe Mechanismen umfasste, so dass “progressive failure” und Verminderung der Gebirgsfestigkeit in Betracht gezogen werden müssen. Dieser Artikel beschreibt vorläufige Ergebnisse einer Reihe von hybriden Modellrechnungen (Finite-/Diskrete-Elemente). Diese haben zum Ziel, explizit das bruchhafte Versagen natürlicher Felshänge zu modellieren, wobei das progressives Versagen im ganzen modelliert wird, von der Anfangsphase über die Entwicklung zum katastrophalen Versagen und den Transport und die Ablagerung der Rutschmassen.

Jan 1, 2003