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By Johannes Labenski, Christian Moormann, Johannes Aschrafi

"Open steel pipe piles are used for various applications in costal engineering, port structures and increasingly important for offshore structures. During the installation of open steel pipe piles the formation of a plug has an influence on the installation process of the pile and also on the final bearing capacity. The formation of the plug depends on different factors, e.g. the pile diameter and the installation method. This paper starts with a structured overview about analytical methods (API, EAP-EAU, UWA-05, HKU-12, Modified API) to calculate the axial bearing capacity of open steel pipe piles. The numerical simulation of the installation process of open steel pipe piles has to fulfill high demands, i.e. to accurately represent the penetration of the pile inside the soil, the formation of the plug and also the stresses and strains during the installation. A numerical back analysis of a comprehensive field test, using the Coupled Eulerian-Lagrangian (CEL) method and a hypoplastic constitutive model for sand, reveals the stresses and displacements of the soil and of the piles. The analysis provides a comprehensive understanding of soilpile interaction.INTRODRUCTIONThe particular difficulty in the numerical simulation of plug formation, is that the effect of plugging inside open ended steel pipe piles has not been fully investigated. In scientific papers different approaches are documented to explain this phenomenon. Some are based on in-situ tests and others are based on numerical simulations. One of the challenges is to determine the end bearing capacity and shaft friction of the steel pipe pile. Different approaches have been developed over the years to determine them e.g. from Randolph et. al. (1991, 1994) and Paik et. al. (2003). Recent approaches are the ICP-05 Method (Jardine 2005), the UWA-05 Method (Lehane 2005) and the HKU-12 Method (Yu & Yang 2012a). A comparison of some methods can be found in Schneider et al. (2010). A plug inside an open steel pipe pile can be visualized as a spatial bracing of soil between the inner surfaces of the pile, cf. Lüking (2010).. However according to Lüking & Kempfert (2012) this bracing only exists for the height in the end of the pile equal to twice its diameter.To identify a plug inside a pile, there are different measurable parameters. One parameter is the development of stresses around the pile during and after its installation. Henke (2013) measured the inand outside horizontal stresses at the pile tip during the installation. The results showed higher stresses on the inside compared to the outside. To validate his measurements he performed a numerical back-analysis of the measured installation process and got matching results."

Jan 1, 2017

By Carlos Varela Castillo

El texto describe el proceso de ensayo de fabricación de arrabio en los hornos eléctricos de reducción de Chimbote, utilizando la escoria de acería eléctrica. Para ello, se muestran los resultados de los cálculos de la escoria, cuadros de análisis de arrabio, escoria y gas de reducción, así como el consumo mensual de materías primas, producción, arrabio, potencia promedio y porcentaje de marcha del horno de reducción. Concluyendo que el uso de escoria elimina el empleo del manganeso y reduce de un 30 a 40% el consumo de piedra caliza por tonelada de arrabio, aumentando la producción del mismo y solucionando el problema de almacenamiento. De otro lado, las dificultades en el uso de la escoria de aceración eléctrica son su falta de homogenidad química y física, y contenido de fósforo que limita su mayor utilización.

Jul 20, 1961

By F. S. McNicholas, R. L. Healy

NOTEWORTHY because of the amount of explosives used, the tonnage broken, and the wide range involved both vertically and laterally, was a large underground blast fired last November at the Hidden Creek mine, Anyox, B. C. Stoping methods and mining prac¬tices at the Hidden Creek mine have previously been described in the technical press. Earlier mining methods employed included shrinkage stoping, glory-holing, and "spiral" stoping. The latter especially has been a practice peculiar to the Granby company, having been used for years at its Phoenix mines and later at the Anyox property where conditions as to size of orebodies and strength of ground both in the ore and walls were similar. These methods all leave tremendous excavations supported at key points by pillars and braces that may only be safely mined by big blasts.

Jan 1, 1935

By S. J. Schatzel

Coal mine longwall face ventilation is an important component of the overall mine ventilation system. Increases in the production rate due to higher capacity mining equipment tend to increase methane emission rates from the coal face, which must be diluted by the face ventilation with a minimal opportunity for assistance from additional control equipment (i.e., surface boreholes). Increases in panel length, in some mines approaching 6,100 m (20,000 ft), and panel width provide additional challenges to face ventilation designs. Face ventilation can also be affected by communication with the methane-laden gob gas reservoir. Except in a two-entry system, belt air cannot be used to ventilate the face in the US, except in limited cases. This relatively recent requirement has further challenged the mining industry in maintaining adequate longwall face ventilation. To assess the effectiveness of current face ventilation practices, a face monitoring study was combined with a tracer gas test on a longwall face. The study was conducted at a US mine operating in a thick, bituminous coal seam with some self-heating tendencies. Multiple gob gas ventholes were located near the face and produced a small portion of ventilation air in their production flow. Initial results show that emission rates on the longwall face showed a very limited increase in methane concentrations from headgate to tailgate despite the occurrence of methane delays during monitoring. Increases in methane concentrations in the tailgate entry in the vicinity of the longwall face T-junction appeared to be produced primarily by gas flow from the gob, not from increased emissions from the face. Barometric pressure variations were substantial over the course of the study and varied on a diurnal basis, as is typical of many mining operations. Suggestions are forwarded for reducing longwall face methane concentrations.

Jan 1, 2012

By Lucas Teixeira Costa

Um modelo matemático foi criado para simular a dessulfuração do aço no desgaseificador RH na condição de uma camada de escória sobrenadante adicionada dentro da câmara de vácuo após a subida do aço sob efeito da pressão. Tomou-se como base o modelo físico do LaSiP (Laboratório de Simulação de Processos) em escala 1:5 para a instalação industrial de uma usina brasileira. A validação do modelo foi realizada por meio da taxa de circulação do modelo físico e de sua simulação. A dessulfuração do aço foi realizada pelo modelo matemático para as condições operacionais da indústria e a avaliação de parâmetros como composição química e volume de escória foram investigadas. Ao final, obteve-se resultados compatíveis com os presentes na literatura e um modelo capaz de prever com grande confiabilidade a evolução do teor de enxofre ao longo do processo de dessulfuração. Considera-se, portanto que a prática de remoção de enxofre no RH é viável e tem-se uma rota adicional/alternativa ao forno panela.

Aug 16, 2017

By Marwa Nabil, Alaa A. Ata

"Recent developments in the analysis of piled rafts has incorporated the load sharing of the raft and the piles to support the superstructure. In the piled-raft system, piles are cast monolithically with the raft and the load is partly transmitted by the raft to the soil directly below it, and partly by the piles to more competent deep soil. While these piles are effective in increasing the bearing capacity and reducing the settlements, they often lead to significant straining actions at the pile head-raft connection which may constitute the weakest link. An attempt to provide a more economical solution, that at the same time overcomes this weak link, is to disconnect the pile heads from the raft and introduce an intermediate cushion of compacted fill. In this case, the piles are considered as reinforcement to the subsoil and will also act as settlement reducers. This paper investigates the load transfers mechanism of the unconnected piled raft with cushion using ABAQUS finite elements Program. The main objective is to provide an in depth analysis of the raft–soil–pile interactions in multi-layered soil under static and seismic loads. The investigated system provides an economical alternative for traditional connected piled raft foundation, where there is no need to reinforce the piles, no need for pile head demolition or expensive waterproofing of the pile head connection. Cost analyses of unconnected versus connected piled raft systems confirmed a cost savings in the construction that may reach from 50 to 70 percent.INTRODUCTIONDesigners around the world have gained more confidence to use the piled-raft as a more realistic system where the raft and the piles share transferring the superstructure loads to shallow and deep soil layers. A further advancement is to use unconnected piled rafts as another practical and economical alternative to the traditional piled rafts. Unconnected piled raft is also synonymous to settlement reducing piles; or simply, soil improvement piles. Liang et al. (2003) has extended the concept of pile-raft-foundation to a new type of foundation called composite piled raft foundation or unconnected piled raft foundation. The foundation is composed of a sand/gravel cushion sandwiched between the raft and piles. The piles group may contain short and long piles. The short piles are constructed of flexible materials such as soil-cement columns or sand-gravel columns, and are used mainly to improve the bearing capacity of shallow soft soil; the long piles, which are made of relatively rigid materials such as concrete, and their main function is to reduce settlements. The cushion plays an important role in mobilizing the bearing capacity of the subsoil and in modifying the load transfer mechanism of the piles. In Shanghai, China, this system of unconnected piled raft has proved to be quite suitable and effective in coastal areas, where deep soft soil deposits exist."

Jan 1, 2016

By C. M. Diaz, S. W. Marcuson

In the late 19th century, the discovery of rich nickel-copper sulfide ore bodies in Sudbury and the need for tonnage quantities of the metal to be used in nickel steel armor provided the foundation for establishing the Canadian nickel industry. For almost 50 years, International Nickel was the key player. In 1930, Falconbridge Nickel entered the field. These two companies remain the key Canadian nickel producers. This paper discusses the factors that have influenced the evolution of nickel smelting processes. The initial Sudbury ore smelting and nickel copper separation technologies were imported from abroad. It was only in 1937 that International Nickel established a process research laboratory in Copper Cliff The explosive post WW II industrial development created a strong demand for a broader variety of nickel products. For both International Nickel and Falconbridge, R&D became an essential business tool to succeed in the new market scenery. In the last few decades, new technologies were developed and commercialized to respond to the raising cost of energy, society pressing environmental concerns, the advent of nickel laterites as an important source of new metal, the incorporation of new nickel producers to the market, and, therefore, the need to increase productivity. Canada thus became an important exporter of technology. In this paper, the authors review this history with the objective of highlighting the forces that have triggered the most important changes in Canadian nickel smelting.

Jan 1, 2005

By Camila Cabrera, Francisca Rivero

El objetivo de este trabajo es proponer un modelo integrado de gestión de cierre de faena minera que permita la transición económica, social, cultural y ambiental de las y los habitantes del territorio en un escenario post-minería. Para ello, se realizó un benchmarking de experiencias de cierre y un análisis comparativo de regulaciones nacionales de Perú y Chile, además de una revisión de estándares internacionales. Asimismo, se elaboró un instrumento con el fin de identificar la información crítica para el diseño de un Plan Integral de Cierre, y una herramienta para evaluar los impactos sociales y oportunidades del cierre de faena.

Sep 29, 2023

By Stanley V. Lachmansingh

Bauxite can be regarded as a mixture of hydrated aluminium oxides the predominant constituent - and oxides of iron and titanium, silica and silicates. Heterogeneous and non-crystaline, most bauxites vary in average composition from one deposit to another both in terns of impurities as well as the proportion of Gibbsita and the Monohydrates Diaspore and Boehmite. Iron levels (as Fe2O3) can vary from less than 1% to as high as 30% with the alumina content ranging from 40 to 6o%,. Gore than 90% of all bauxite mined in Guyana is used as feed for the - production of refractory grade calcined bauxite. There are -however, several speciality grades used in various industrial applications and these are characterised by the quality of the bauxite in particular ;,with regards to iron and silica levels which generally have to be low. The main speciality grades are designated Refractory, Abrasive and Chemical. Bauxitte is also used in the production of nigh alumina cements,, activated bauxite end in the manufacture of electrical insulators.

Jan 1, 1977

By Max R. Peña W

El crecimiento de la minería en el Perú requiere de un adecuado desarrollo tecnológico, así como de la reducción de costos en las mismas operaciones. Por ello, en la actualidad minera se desarrollan alternativas para la reducción de costos en perforación y voladura a través de las técnicas de corte escalonado y los detonadores eléctricos de alta precisión, a fin de obtener un mejor rendimiento en cuanto a su funcionamiento y precisión en minería subterránea y de cielo abierto.

Nov 24, 1993

Reduce the potential for injuries in underground mines by providing an alternative to manually lifting and holding heavy roof-support beams. The Problem I-beams, rail sections, and wooden cross-beams are often used in mine haulageways where extensive roof support is needed. Studies by the Bureau of Mines have shown that many mines must resort to manually lifting, moving and installing these beams. Such manual-handling activities have the potential for causing injury to mine workers, particularly back injuries. I-beams used for roof support can typically weigh from 400-500 lbs. Rail sections weigh about the same as the I-beams. Wooden beams can weigh from 200 to 300 lbs. To lift a single beam usually requires the efforts of 3 to 5 mine personnel.

Jan 1, 1988

By Seoul National University, Ki-Ho Kim, Jong-Pyo Kim, Sung-Min Joo, Hee-Chan Cho, Hyung-Seok Kim

Aragonite was synthesized in addition of Mg2+ ion and SrCO3 seed by carbonation process, and the best condition and mechanism of the synthesis was studied by analysis of continuous pH change, ICP, XRD, and SEM. As MgCl2•6H2O addition increased, aragonite phase increased at condition of CO2 flow rate of 100 mL/min and stirring rate of 250 rpm. It was the dissolution of Mg(OH)2 that determined overall reaction time. As SrCO3 seed addition increased at 0.2 mole MgCl2•6H2O, the amount of aragonite increased and the aspect ratio was from 5 to 9. And it was thought that Mg2+ ion prohibited calcitetransformation of aragonite formed by SrCO3.

Jan 1, 2003

By A. E. Jenkins, L. A. Baker, N. A. Warner

Rates oj decarburization of levilated Fe-C droplets conlaining 5.5 to 0 pct C have been measured at 1660°C. Gas mixtures of 1, 10, and 100 pct 0, with helium diluenl were used at velocities of 12.5 and 62.5 cm per sec. Rates were independent of carbon concentration in the mell and in good agreement with the calculated rule of oxygen diffusion through the gas boundary layer. The effects of flow rale and total pressure are as predicled and the rates are approxitnalely 2.5 times those with CO2 as oxidant. The mass-transfer correlation used incorporaled the efject of natural convection as well as forced conrection. Graphile spheres are shown to oxidize at the same rate as Fe-C droplets under the same experimental codlions. It is concluded that, for high carbon concentrations in the melt, the rate of- decarburizalion is controlled wholly by the rate of gaseous diffusion. Rate measurements with pure CO, are reported for low carbon concentrations where CO bubbles nucleate within the droplet. Under these circumstances the decarburi-zation decreased with carbon concentration and it is proposed that carbon diffusion is significant in conlrolling the decnvburization rate. In an earlier paper1 decarburization rate measurements were reported for levitated Fe-C alloys at 1660°C but with CO2 as the oxidant. The decarburization rate was found to be independent of carbon concentration in the melt but slightly affected by total pressure. The authors were unable to explain the slight pressure effect but in all other respects the results were consistent with control by diffusion in the gas boundary layer. Subsequent work has been directed at finding the reason for the slight pressure effect and whether the kinetics with oxygen as oxidant parallel those with CO2. Recently Ito and Sano2 have shown that with water vapor-argon atmospheres the decarburization rate is gaseous diffusion controlled until an oxide film appears on the surface. In this work the melts were contained in crucibles. MASS TRANSFER IN THE GAS PHASE In the earlier analysis1 only forced-convection mass transfer was considered. Subsequent recognition of the existence of some free-convection mass transfer explained the observed small effect of total pressure on the decarburization rate. Steinberger and Treybal3 and Kinard, Manning, and Manning4 have developed correlations involving the linear addition of the contribution of radial diffusion, free and forced convection. Steinberger and Treybal&apos;s correlation was chosen as the most applicable to the present work since it correlated most of the data available in the literature and handled the low Reynolds number region exceptionally well. The correlation for (Gr&apos;Sc) < 108 is where Nu&apos; is the Nusselt number for mass transfer based upon the total surface of a sphere in an infinite medium, G&apos; is the mean Grashof number for mass transfer defined by Eq. [2], Sc is the Schmidt number (µ/pDAB)f, Re is the sphere Reynolds number (dpu,pf/µf), p is the viscosity of the gas (poise), p is the density of the gas (g cm-3), Dab is the binary diffusivity for the system A-B (sq cm sec-&apos;), dp is the sphere diameter (cm), u is the approach velocity of the gas (cm sec-I), and subscript f denotes the property value is computed at the film temperature Tf defined by Tf = +1/2(To + Tr) where To is the specimen temperature and T, is the approach gas temperature (oK). Natural convection occurs when inhomogeneities exist in gas density. These may be caused by concentration gradients, temperature gradients, or both. In the present work the temperature gradient between the sphere and the bulk gas was very large and in some cases, for example the runs with pure oxygen, the concentration gradient was also appreciable. The Grashof number defined by Mathers, Madden, and piret5 was used since it took account of both temperature and concentration gradients: where Gr&apos; is the Grashof number for mass transfer (p2fgd3|-yA-yA|/µ2f), Gr is the Grashof number for heat transfer (p2f gd3p|To - T,]/µ2fTf), Pr is the Prandtl number (cpµ/k)f, g is the acceleration due to gravity (cm sec-&apos;f, a is the concentration densification coefficient (1/p)(ap/ayA)T, yA is the mole fraction of component A at the gas-metal interface, yA is the mole fraction of component A in the bulk gas stream, cp is the heat capacity of the gas per unit mass at constant pressure (cal g-I OK-&apos;), and k is the thermal conductivity of the gas (cal cm-&apos; sec-1 OK-1). Mathers et al. tested this combined Grashof number

Jan 1, 1968

By Y. Wang, E. Forssberg, A. Johansson, B. Chan

A super-conducting high gradient magnetic separator with matrix vibration in dry separation mode is a powder purification device, which has been used to remove weakly magnetic impure particles from fine calcite powders below 53 µm in this study. A fundamental question concerned is the evolution of the matrix clogging under gas-solids loads. This paper presents the improvement of the separation selectivity using a method of mechanically based vibration on the matrix in the separator. The functions of the matrix vibration are discussed. The results indicated that the mechanically based vibration on the matrix within a high intensity magnetic field while a feed was introduced in an air stream, was found to be effective for the dry purification of fine powder materials.

Jan 1, 2001

By G. M. Ritcey, K. E. Haque

"Laboratory-scale sulphuric acid leach tests were conducted on Elliot Lake and Rabbit Lake ores in the presence of various oxidants, namely: Fe2(SO4)3, CI2, H2O2, NaClO3, MnO2, H2SO5, HNO3, Oxon e, K2Cr2O7, KMnO4, O3 and O2. Uranium extraction is significantly accelerated when an oxidant is present in the leach slurry. Uranium extraction of 96-99% can be achieved by maintaining the oxidation potential of the leach slurry in the range of400 to 500 m V (S.H.E.). A rough cost comparison of all the oxidant s indicates that the use of Fe2(SO4)3, 02, O3, C12, HNO3 or MnO2 is far less expensive than NaClO3 and the uranium extraction rates are similar to or better than with NaCIO3. For uranium extraction, it is concluded that gaseous oxygen (i.e., air or oxygen) would be the most effective and economical oxidant for the 24- to 36-hour leach of Elliot Lake ore; whereas for the 8- to I2-hour leach of Rabbit Lake ore, a strong chemical oxidant (e.g. NaCIO3, H202, 03, K2Cr2O7, H2SO5 or HNO3) would be a logical choice.IntroductionThe common practice for the treatment of uranium o res is leaching with sulphuric acid or with a carbonate-bicarbonate mixture. Generally, the latter process is ad opted when an excess (> 18%) of acid-consuming components (e.g., carbonate) is present in the ore. Irrespective of the nature of the leachant, the addition of an oxidant to the leach mixture is necessary to obtain a high uranium extraction.The maximum extraction of uranium can only take place when all the uranium is in the highest oxidation state (i.e.,U +6-uranic ion) . Because a certain percentage of uranium present in the ore is invariably in the lower oxidation state (i.e.,U+4-uranous ion) , the addition of an oxidant to the leach slurry is necessary to oxidize uranous ion to the uranic state."

Jan 1, 1982

By D. L. Russel

El hidrociclón tiene una función importante en las operaciones auxiliares del beneficio de minerales, ya que separa los sólidos suspendidos de la pulpa de alimentación en dos fracciones, eliminando las partículas nocivas. Por tal motivo, el objetivo del texto describe ejemplos de ciclones activos en las concentradoras de la mina de Cerro de Pasco, como sus características. Los ciclones desarrollan tres clases de trabajos: la clasificación en circuito cerrado o de molienda, deslamamiento antes de flotar y el espesamiento y deslamamiento al circuito de filtración. El primero ejemplo, se realizó en la concentradora Paragsha con remolienda de cobre, el segundo se relaciona con flotación de pirita y el último, con filtración de cobre y zinc en la concentradora de Huarón. Producto de esta revisión a los ciclones, se encontró que la facilidad y costo de fabricación de aparatos experimentales, flexiblidad en el uso, comodidad de instalación y el poco espacio requerido, condicionan el uso del hidrociclón en varias operaciones de clasificación y espesamiento al tiempo que reemplazarán las clasificadoras clásicas por circuitos de molienda primaria

Jul 20, 1960

By Thomas M. Barczak

A critical safety component for all underground mining is intrinsic and standing support systems. Specifically, tabular hardrock mining exploits a wide variety of deposits that require various methodologies to safely mine the ore material. Several new support systems have been developed in recent years for hard rock applications which have been modified or applied in a variety of ground control applications. These include prestressing devices, improved cribs, and free standing supports. Various standing support and prop-type systems have been designed for hard rock applications with seismic loading conditions to accept prestressing. The prestressing, using water-filled cells, creates an active load upon installation and is considered essential to maintain support during and after the blasting of the mine faces. Heavy seismic activity is also present in these mines and the prestressing units can provide some energy absorption capability to help preserve the integrity of the support. This paper presents an overview of these innovations in support technology.

May 1, 2007

By Cristiane Lazzaro Barbosa

Visando a melhoria contínua no atendimento a seus Clientes, além de garantir a confiabilidade e rastreabilidade do processo de tratamento das manifestações de seus clientes e dos sinistros ocorridos com os produtos adquiridos, a ArcelorMittal Brasil Planos investe na atualização do sistema que suporta este processo e na convergência para o SAP. O Projeto, denominado QM Comercial, utilizou os módulos QM, DMS, SD e WF do SAP ECC para implementar a solução de registro, documentação, elaboração do parecer com a análise de várias áreas/unidades da empresa e a orquestração das atividades dos processos comerciais/financeiros de conclusão da reclamação/sinistro. Todas as etapas com rastreabilidade e controle de tempo de resposta das áreas envolvidas.

Aug 16, 2017

By Nickol Estrada, Jean Paul Bueno, Jhonatan López

El presente proyecto consiste en la identificación de un nuevo dominio en el yacimiento tipo VMS de Cerro Lindo que hasta el dominio estaba considerado como roca caja y para incluir dentro del modelo era necesario reducir la incertidumbre y demostrar su beneficio en la planta. La metodología aplicada parte desde toma de datos logueo, mapeo subterráneo que posteriormente es usado en las interpretaciones geológicas y estás a su vez son usados para elaboración de los sólidos geométricos de los diferentes dominios, luego en base a la data y los sólidos geológicos se aplica todo el análisis geoestadístico (EDA, capping, compositación y variografía) además de ello se aplicó un estrategia para mejorar la estimación, se trata de la anisotropía dinámica para la búsqueda de muestras en base a superficies de tendencia mineral que es una combinación de la geología estructural y interpretación de minerales de alta/baja temperatura (ratio de knuckey Cu/(Cu+Zn)).

Sep 30, 2022

By Vicente Palacios Palacios

El presente trabajo describe los diferentes controles de calidad que se efectúan en la refinería de Ilo de Southern Perú Copper Corporation para la obtención del cátodo de cobre. Los controles son de carácter físico y químico y se realizan durante el proceso y producto final. Para ello, se presenta una descripción sistemática de los procedimientos estadísticos basados en datos obtenidos en nuestras instalaciones y es el control de calidad que emite juicios sobre la base de hechos y no sobre las conjeturas. Las herramientas utilizadas son técnicas para descubrir problemas, organizar información, generar ideas, analizar causas, efectuar mejoras y establecer control, evaluar las necesidades de una mejora continua para superar las expectativas de nuestros clientes, promover el desarrollo de nuestro recurso humano y la conservación del ambiente. Como consecuenci de esta aplicación del control de calidad en los cátodos, se ha incrementado la productividad en el laboratorio, ha mejorado el tiempo de respuestas de los ensayos, así como la disponibilidad de información y tendencias de los resultados para todos los usuarios de la refinería, constituyéndose en una herramienta para la toma de decisiones en los diferentes niveles gerenciales y los ensayos del laboratorio.

Jul 31, 2003