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By Juan Oswaldo Alfaro, Angel C. Nuñez, Hildebrando A. Cóndor

Se ha desarrollado un software para facilitar la evaluación del proceso molienda-clasificación en plantas concentradoras. Se ha modelado en UML-Lenguaje Unificado de Modelado; los datos e información se almacenó en SQL Server; se programó en Java (Programación Orientada a Objetos). Investigación Aplicada y Cuantitativa obteniendo como resultados un Software para Circuito de Molienda-Clasificación (Directa e Integral).

Sep 1, 2017

By A. Korchevisky

Environmental self-monitoring is one of the advanced approaches for industrial sustainability programs. Organization for Economy Cooperation and Development (OECD) defines self-monitoring as ?the system of organizational and technical measures put in place and financed by [the] regulated subject? in order to ensure their compliance with regulatory requirements?1. Self-monitoring is beneficial for industrial operators, communities, and governments. Industrial companies use self-monitoring as a central element of their compliance management that allows them to fulfill their duties, obligations, and to avoid citations. When industries control their emissions and ensure workers are not exposed above the regulated limits, communities are better. It is impossible for an EPA, OSHA, or MSHA inspectors to be close to every emission source or workplace full-time. It is much more effective for industries to self-monitor, under due supervision. Occupational conditions are a very important part of industry and health and safety self-monitoring should be highly prioritized. In this paper we will research the regulatory basis and best practice of occupational self-monitoring. We will show that not only is self-monitoring a vital element of an occupational health & safety management system, but that you need a management system for affective monitoring.

Jan 1, 2012

By Walter Ensinger

Special foundation works is one of the most innovative sectors in civil engineering and construction. Both engineering techniques and construction machinery are undergoing continu­ous further development. These developments are providing ways to meeting the world-wide requirement for special geotechnical works even faster, even better and more efficiently. Unfortunately, accident prevention organisations have had to realise that the figures on in­dustrial accidents in special foundation works are still above average in number. The Safety & Environmental Working Group of the EFFC thereupon started to carry out a survey on acci­dents occurring in this sector and used this information as a basis for the preparation of acci­dent statistics and an accident analysis. The objective of this undertaking is to determine key accident occurrences and their causes and to consequently determine measures for improved health and industrial safety.

Jan 1, 2002

By L. W. Vigrass

Porous and permeable rocks deeply buried in sedimentary basins contain immense volumes of hot water with the potential to supply low-grade heat energy. A part of Canada with sizeable potential for low-grade geothermal energy is the northern Williston Basin of southern Saskatchewan. In this region, the University of Regina has conducted a geological study investigating the feasibility of producing large quantities of warm water suitable for space heating in the Regina - Moose Jaw area. The study has shown that the most favourable geothermal reservoirs are in the Basal Clastic Unit (Cambrian Ordovician), which, at an approximate depth of 2,000 metres has predicted temperatures of 71°C to 74°C. We anticipate sustainable flow rates from these reservoirs of 100 to 300 ms/hr. The water contains about 150,000ppm of total dissolved solids, mostly sodium chloride. It is anticipated that the sulphate content will be 3,000 to 6,000 ppm, that the dissolved oxygen and hydrogen sulphide content will be small, and that the waters will be neutral to slightly alkaline. It is anticipated that the piezometric level will be 46 m below the ground surface for reservoirs in the upper part of the Basal Clastic Unit and 141m below the ground surface for the lower reservoirs of the unit. Plans are to build a low-grade geothermal research, testing and demonstration facility at the University of Regina. To be a practical demonstration, the facility will have to handle very large volumes of water. Because of high salinity, the water will be re injected into a subsurface reservoir. We do not anticipate insurmountable problems because of salinities or as a result of corrosion provided that the waters are not aerated during handling

Jan 1, 1979

By B. S. Xakalashe

Keywords: Pyrometallurgy, silicon, solar cells Silicon has been the dominant material in the photovoltaic (PV) industry since its application in the space industry in 1958. This review focuses on crystalline silicon solar cells, primarily due to their dominance in the photovoltaic industry, omitting other photovoltaic cell technologies such as second generation (e.g. thin films) and third generation (e.g. nano-structured solar cells). The value chain for the production of crystalline silicon solar cells has been reviewed. The primary processing steps for the production of silicon solar cells from quartz are as follows: bulk production of metallurgical-grade silicon via carbothermic reduction in a submerged furnace, refining of metallurgical-grade silicon via the chemical means to polycrystalline silicon, or through the metallurgical route to solar-grade silicon, wafer manufacturing, and, lastly, silicon solar cell manufacturing. During downstream processing, solar cells are interconnected and encapsulated into solar modules (panels), which can be used individually or incorporated into a photovoltaic system for electricity generation and supply. The cost for crystalline silicon based solar cells is approaching one US dollar per watt peak ($1/Wp), while the most cost-effective solar modules in industry have reported costs below $1/Wp, and are based on CdTe thin films. Solar cell energy conversion efficiencies as high as 22% have been reported in industry for crystalline silicon solar cells.

Jan 1, 2011

By Neldon L. Jensen

Although ASARCO Incorporated, the only domestic producer, had terminated copper smelting operations and associated recovery of byproduct arsenic trioxide at Tacoma, WA, in 1985, it shipped small quantities of both trioxide and metal from its remaining stocks in 1986. Imports for consumption of arsenic trioxide increased significantly, owing to increased demand for arsenical wood preservatives and the decrease in domestic shipments of trioxide. Prices remained unchanged throughout the year. Development of gallium arsenide integrated circuits, important in advanced military and commercial electronics circuitry, continued to gain momentum during 1986. Domestic Data Coverage.-Shipments of small amounts of arsenic trioxide and metal from remaining stocks by Asarco were reported voluntarily to the Bureau of Mines.

Jan 1, 1988

By A. D. S. Gillies

The use of refuge chambers for use in handling underground emergencies is an issue of topical relevance within the US mining industry. Chamber design is of importance to meet some new safety requirements of US federal and some state government mine regulations. A review has been undertaken of a steel mine refuge chamber design to predict what will be internal temperature within the chamber over an extended period with miners present? The design has been examined for the situation when the chamber is sited in still mine air. Spreadsheets have been developed to allow various design assumptions to be tested. The evaluation has been undertaken using thermodynamic heat transfer models with some assumptions specified to produce a model of appropriate simplicity but with adequate degree of accuracy. Under normal still air conditions it can be seen that internal chamber conditions rise quickly to often arduous conditions. There will always be quite a few assumptions necessary in complex heat transfer process evaluations. Some important refuge chamber design parameters are: ? External surface area of the chamber, its wall thickness and construction. ? Metabolic heat generated and number of persons making use of the chamber. ? The temperature of the external mine atmosphere to the chamber over the year and the influence of geothermal gradient on temperature at depth. ? The maximum internal chamber Apparent Temperature considered safe. ? The distance inside the underground mine and adjacent ventilation conditions.

Jan 1, 2012

By Eder Salazar

El presente texto describe la optimización de la productividad en la empresa minera a través de la mejora contínua en la cadena de valor en SMEBSAA, los siete pasos de la calidad, proceso de mina, planta, soporte y la cuantiificación de dicha mejora en la cadena de valor en SMEBSAA. Asimismo, la implementación de los diversos sistemas de gestión refuerzan los resultados, siendo el Sistema de costeo basado en actividades el gran agrupador de toda la información de los módulos: Logístico, Control Patrimonial, Orden de Servicio, Planillas y Contabilidad.

Sep 12, 2005

By Hiren J. Shah

The urban environment and geology create unique challenges for design and construction of deep foundations. The effect of these is prominently experienced in New York City. Three such project case histories are presented in this paper. The first project is a multi-use development. Relatively unusual glacial geology was observed at the site during the subsurface investigation phase. This played an important role in the selection of deep foundations as well as during construction. The design and construction aspects of the pile foundations, settlement estimates, a pile drive test program during design, piling equipment and production pile installation are discussed herein. A relatively smaller project is the second case history. A combination of drilled and driven deep foundations was employed in one area of the project due to its unique conditions. In another area of the project, an addition to a structure required the use of supplemental foundations to resist new additional loading. Tight space and load sharing with the existing foundations were important considerations in the design and construction. Finite element modeling of the existing and completed structure was performed which was an interesting aspect of the project. The third project case history involves a very large multi-billion dollar project in which various different types of deep foundation elements were used. The aspects requiring the use of such a variety of types and sizes of deep foundation elements included: geologic conditions, re-use of existing foundations, protection of adjacent infrastructure, construction staging, restricted space, loads, deep excavations, cost and schedule.

Jan 1, 2011

By F. Baerhold, S. Mitterecker

"Acid recovery is an important process step in pickling and leaching processes. Pyrohydrolysis in spray roasters and fluidized beds is a well-established technology to recover hydrochloric acid, but the hydrolysis in the liquid phase is more and more considered as an alternative new process route. The characteristic features of these three processes will be discussed along with select industry trends. For example, hydrochloric acid based leaching processes for ilmenite and nickel laterite ores produce far larger volumes of waste acid streams than the steel industry. Scaling-up of the spray roasting technology to the highest possible capacity is necessary in order to become more cost effective. In addition, process routes based on ferric chloride pyrohydrolysis allow the production of super-azeotropic HCl (up to 30 wt.%). Finally, the new ECOmode concept optimizes the operation of both pickling lines and the spray roast acid recovery plant. Long term results from industrial applications show that fuel savings in the spray roaster of 25% are easily achieved without additional process steps. An attractive feature is also to upgrade existing installations to higher plant capacities.INTRODUCTION Pyrohydrolysis is the conversion of metal halides into metal oxides at elevated temperatures in the presence of water vapor. Reaction products are a hydrogen halide gas and a metal oxide. The process was originally developed and introduced into the market by ANDRITZ Ruthner in the 1960’s. It has found wide technical application in the field of acid recovery and oxide production. The introduction of this process has revolutionized pickling technology. The use of hydrochloric acid has strongly increased over the last decades, since pyrohydrolysis is available for the total recovery of waste pickle liquors from mild steel pickling, as illustrated in Figure 1.Chloride media are also used increasingly in the metallurgical industry. Oxide production processes for Mg, Co, Ni, and Al have been installed. Processes using hydrochloric acid are known for the leaching of ores as well as for the re-extraction of metals from organic solvents. In both cases the recycling of HCl is of substantial importance to achieve highly economic processes and to reduce waste."

Jan 1, 2016

By Lorraine B. Burgin

This study by the Bureau of Mines documents the leadtime required for preliminary and detailed exploration, development of the mine, and construction of beneficiation and support facilities for selected copper deposits in Arizona. The time for major exploration ranged from 1 to 15 years, time for open pit development (or construction) was 1 to 4 years, and time for under- ground development was 4 to 8 years; one underground mine presently being developed may require 12 years to achieve production. Construction of the beneficiation plants required 8 months to just over 2 years. The data are supported by historical facts for each deposit during the leadtime stages from location of claims through exploration, construction, expansion, and leaching. The sequence of development and factors contributing to differences in the time spans are discussed. Histories are detailed for the Miami, Castle Dome, Copper Cities, San Manuel-Kalamazoo, and Twin Buttes properties; briefly summarized are the Pinto Valley, Miami East, Esperanza-Sierrita, Pima, and Mineral Park Properties. Each mining operation had its own pattern of development, and together they present a source of planning information for the development of other properties.

Jan 1, 1976

By B. B. Broms

Embankment piles are common in the Scandinavian countries (Kjellman, 1940) and in Southeast Asia as support of fills, light structures, bridge abutments and deep excavations (Eide, 1968) as described in the following. Untreated timber piles are often used for light structures and shallow fills when the ground water level is high since they are inexpensive and readily available. When the applied loads are relatively high precast concrete piles and steel piles are preferred. DESIGN CONSIDERATIONS Embankment piles carry the load from a fill or a struc-ture either through skin friction along the sides of the piles (Fig. 1a) or through a precast concrete slab or through pile caps at the top of the piles (Fig. 1b). When the load is carried by skin friction it is often economical to use small diameter timber piles because of the large surface area (Asplund, 1939). For precast concrete or steel piles concrete caps are used to transfer the load to the piles due to the relatively high capacity of the piles since the skin friction resistance alone is not sufficient to transfer the load to the piles.

Jan 1, 2010

By Donald A. Bruce

The paper reviews aspects of the construction and performance of prestressed ground anchors installed in soils and weak rocks. Attention is focused on good practice for drilling, tendon fabrication and handling, grouting, stressing and testing. Regional variations - not always logically justified - are described. The performance of anchors in a variety of geological conditions is illustrated with reference to recent full scale test programs. 1. Introduction In the United States there has been steady growth in the use of prestressed anchors in materials other than competent or hard rock, in the years since their introduction in the late 1960's. This expansion has to a large extent been driven by specialty geotechnical contractors who both imported foreign developments and conducted their own basic researches, in locally prevailing conditions. With such data and experience, these engineers have had the confidence to promote "alternative solutions" for difficult earth support problems to receptive designers and owners. In turn, being engaged in the details of design and performance monitoring has given these parties the close exposure necessary for the real transfer and understanding of the technological concepts, and this knowledge has generated positive feedback for the contractors.

Jan 1, 1991

By Mustafa Fener, Masoud Rostami, Sair Kahraman, Behnaz Dibavar

Roadheaders are commonly used in coal mines for roadway excavations. The prediction of roadheader performance is necessary for the planning of roadway projects and the estimation of costs. Recently, a new rock mass cuttability classification (RMCC) system has been introduced for roadheaders used in coal mines. In this study, the validity of the RMCC system was investigated for different types of roadheaders and different coal mines. Four different coal mines were visited, and the performance measurements of different axial and transverse roadheaders were carried out during the excavation of roadways. Uniaxial compressive strength, volumetric joint count, the strike and dip of joints, joint aperture, the Cerchar abrasivity index, and water ingress were determined in field and laboratory studies to calculate the RMCC index. The analysis of the data demonstrated that the correlation coefficients between the net cutting rates and the RMCC indices were higher than 0.94, suggesting that the RMCC system was valid. It was concluded that the RMCC system could be reliably used for the evaluation of roadheader performance in coal mines.

Jun 21, 2023

By Roberto Folchi, Hans Wallin

Having so many norms and technical content of legislation to deal with is a problem that an explo-sives engineer has to face, especially when working at an international level. Each country has its own norms and legislation, sometimes even each other region or state, as if the physics of explo-sions, rock, concrete, and masonry characteristics would change across the borders. Both norms and laws are frequently out of date, being mainly developed at the beginning of the previous century and adjusted, piece by piece, to a technical and political context that is constantly changing, with adjustment being frequently adopted in a hurry, due to a problem arising such as that of internation-al terrorism. Sometime also, norms are not harmonized with those they intend to amend, so required explanations and new adjustments lead to a vicious circle that increases confusion, complexity and depresses the explosive industry.

Jan 1, 2015

By Mario E. Rossi

Las simulaciones condicionales geoestadísticas se utilizaron como herramientas de control de leyes en operaciones diarias que evalúan la incertidumbre y el riesgo de las reservas mineras en estudios de factibilidad, así como el potencial de mineralización en ciertos ambientes geológicos. Otras aplicaciones incluyen evaluación de recursos y reservas recuperables (dilución), clasificación de recursos y reservas, y optimización de espaciamiento de sondajes. En ese sentido, el presente trabajo señala los aspectos de los esquemas de clasificación de recursos y reservas utilizados en la industria, el cual está basado en el modelo de incertidumbre que las simulaciones condicionales proveen. Asimismo, se analiza el riesgo que este modelo de incertidumbre implica para sub-regiones (unidades) de extracción del yacimiento, como las definidas por fases de extracción mineras o períodos de tiempo.

Jul 17, 2000

By Michel Doyon

Canadian Context: Exploration ??Space Exploration is within the unique mandate of the Canadian Space Agency ??Global partnerships ??Maintain close relationship with our partners ??New knowledge in S&T ??Retain and attract highly qualified personnel ??Participation in missions leads to design roles in industry and academia ??Collaboration between government laboratories, industry and academia

May 1, 2009

By Jacques J. Eksteen

Any effort to improve the metallurgical control of industrial furnaces employed in the primary extraction of high carbon ferroalloys are bound to fail unless the variability of the melt is not fully accounted for. A number of sampling campaigns were performed on both 3phase AC submerged arc and single phase DC open arc furnaces at different smelter sites in South Africa where High Carbon Ferrochrome is produced. It was found that the heterogeneity between multiple samples during a single taps were much higher that for heterogeneity found within a sample. Moreover, this heterogeneity (as quantified by the relative standard deviation per tap) varied with the operating conditions of the furnace, the element monitored and the type of furnace. A relationship was found between the relative standard deviation of certain elements and the degree of subcooling of the melt.

Jan 1, 2006

By William J. Neely

Augercast piles are formed by drilling a continuous-flight auger into the ground and, on reaching the required depth, sand-cement grout or concrete is pumped down the hollow stem as the auger is withdrawn. The sides of the hole are supported at all times by the soil-filled auger, eliminating the need for temporary casing or bentonite slurry. The augercast piling method is fast and economical; there is no vibration, very little noise and, if executed properly, no ground displacements during installation. The method is well suited to sands which are easy to drill and are readily transported up the auger. Relatively little attention has been given to augercast piles in the literature which might be part of the reason for the considerable variations in local practice, building code requirements and design methods. The purpose of this paper is to discuss some of the features of augercast pile installation that are known to influence both the structural and geotechnical capacity of the pile, to evaluate several empirical design methods and to look at some important aspects of quality control of augercast pile installation.

Jan 1, 1990

By M. Moagabo

CO2 emissions from carbonate laden reclaimed mine spoil has been shown to pose a hazard to residents in homes built on or adjacent to such land. The objective of this project was to develop a soil CO2 flux survey protocol for assessing reclaimed mine land. The research involved CO2 chamber accumulation flux surveys; stable carbon isotope ratio analysis; statistical hypothesis testing to examine correlation between CO2 flux and soil temperature and moisture as well as spatial dependence; and geostatistics to map CO2 and delineate high flux zones. Soil temperature was observed to have a positive correlation with fluxes while soil moisture was observed to be negatively correlated. Spatial dependence of CO2 fluxes on reclaimed mine land was observed on one of the two study sites. The research suggests that macro-porosity and gas permeability may be important factors that explain CO2 migration in mine spoil. A flux survey protocol has been developed, based on these results, for reclaimed mine lands. The work demonstrates the capability of geostatistical methods to delineate high flux fields. Further research will be required to determine suitable thresholds for such analysis.

Jan 1, 2012