Search Documents

By Germán Mallén

Como parte de los estudios línea base realizados por MWH Perú S.A. para el proyecto aurífero Chucapaca de las Canteras del Hallazgo en el distrito de Ichuña de la región Moquegua, Perú, se investigó el origen de boro, alta salinidad y otros componentes que perjudican la aptitud de los ríos Ichuña y Tambo para irrigación y otros usos. En este sentido, se encontró que la calidad de agua es perjudicada principalmente por altas concentraciones de sodio, entre otros, precipitándose como hidróxidos de estos metales debido al pH neutro en el río. En ese sentido, el presente texto describe la relación de este impacto químico con los manantiales entre el Cerro Chucapaca y el cañón del Río Ichuña/ Alto Tambo, ubicados al Norte de Moquegua, donde presentan la característica distribución de diferentes tipos de aguas volcanogénicas sobre un sistema de convección hidrotermal de agua meteórica profunda reciclada, calentada y movida por una cámara magmática andesítica que aporta calor y gases.

Sep 21, 2013

By K. Lombard

"‘Roof support awaiting time’ (RSAT) is a term used at Goedehoop Colliery’s Simunye Shaft to describe the potential production time lost due to the continuous miner (CM) standing idle waiting for roof support to catch up. Investigations revealed that in 2013, Simunye Shaft had approximately1400 hours of RSAT, which suggests that the mine could have potentially produced an additional 280 000 t of coal. This project consisted of two parts. Firstly, the causes of the high RSAT and means to improve the situation were investigated. Secondly, as insisted by mine management, the CM cutting sequence was investigated as a possible cause of high RSAT. Machine-related challenges due to the roofbolter installing support too slowly, geological conditions (mostly hard roof conditions and slips),logistical challenges pertaining to the CM cutting sequence, man-related challenges related to operator fatigue, re-support, operator inexperience, and the absence of support targets were identified as main contributors to RSAT. Furthermore, results showed that the roofbolters in the sections at Simunye Shaft are slower than the CMs. A target of 28% reduction in RSAT was set. Experts from Kennametal and Fletcher were consulted to find solutions for the identified causes. In total, eight solutions for RSAT were identified, but the solution that contributed most significantly to reducing RSAT was to use hard roof drill bits as a standard product at Simunye Shaft. Calculations showed that by using hard roof drill bits, RSAT can be reduced by 43%, which is more than the specified 28% target. The cutting sequences at Kriel, Greenside, and Simunye Shaft, togetherwith three newly developed cutting sequences, were simulated using the UCMS (Underground Coal Mining Simulation) program. A re-aligningprinciple was incorporated into the newly developed cutting sequences toalign the cutting sequences to general support work and to reduce RSAT. A decision matrix revealed that a cutting sequence in which boxing takesplace in R3 (third road to the right of the belt road) and in which the re-aligning principle has been incorporated will be the best option for Simunye Shaft. The recommended cutting sequence will lead to a 5% increase in production.The work presented in this paper was carried out as partial fullfilment for the degree BEng (Mining Engineering)"

Jan 1, 2015

By Jorge Díaz A

El presente texto revisa los métodos utilizados en las minas de tajo de abierto como son la perforación, disparo y seguridad y así mejorar los standars y el rendimiento futuro en la industria minera. Respecto al primer método empleado, se analizan los factores que afectan el rendimiento de brocas y cómo dicho factores varían, impidiendo la adaptación de prácticas universales de perforación. Asu vez, estos mismos permiten seleccionar el tipo de broca adecuado y mejorar el máximo rendimiento del mismo. En cuanto la voladura y los explosivos, se revisan las variables fundamentales que ejercen una influencia sobre el resultado de un disparo y así realizar un estudio comparativo de los agentes explosivos en uso, tratando de interpretar el mecanismo de la explosión y a la vez aplicarlo a las diferentes formaciones presentes en Cerro. Finalmente, se describe la organización del sistema de seguridad y las obligaciones de este comité en la industria minera.

Aug 20, 1965

By Ali Porbaha

The use of soil nailing technology as a cost effective alternative for excavation support and slope stabilization has substantially increased in the United States during the last decade. For example, in the past thirteen years, more than 185,800 square meters of soil nail walls have been constructed in California alone. The conventional soil nail systems pose difficulties when ground conditions are subject to caving, for instance for silty sand (sugar sand) or cobbles and boulders. The construction industry has developed self drilling hollow bar systems (or pressure injected bored, IBO) that combine both drilling, placing and grouting in a single operation as a solution to speed up construction. While the system is extensively used for temporary applications, nevertheless, some concerns, particularly about corrosion, has limited the use of this technology as a permanent system in North America. This study presents several issues related to self drilling soil nail systems, the results of a field investigation and a summary of the research project.

Jan 1, 2006

By G. S. Scott

In the course of the investigation into the causes, behavior, and control of mine fires, which the Bureau of Mines is now conducting, some attention was given to the subject of spontaneous heating. It is self-evident that the temperature of a pile of broken coal will rice if the rate of generation of heat exceeds the rate of brat dissipation and will fall if the opposite is the case. Factors that affect the rate of generation of heat are:

Jan 1, 1941

By Tracy Brettmann, Will Bohlen

An innovative retaining wall design consisting of tangent drilled shafts with supplementary seal piles was used to limit continuing bank erosion along the Brazos River in Southeast Texas. The riverbank erosion had progressed to where it was threatening the stability of both the bridge abutment and corresponding approach embankment of the heavily travelled Highway 99 bridge at this location. A tangent pile design was selected because it was both much faster to install and more cost effective than a secant pile system. The design included both 5.5-ft and 10-ft diameter shafts with depths up to 130-ft and comprised both anchored and cantilevered sections. Supplementary seal shafts were also installed between the structural tangent drilled shafts to help plug any gaps between the tangent shafts. The plumbness and diameter of the shafts were tested using a sonic caliper to make sure the shafts were installed within the specified tolerance. The initial design had to be revised when a record flood from Hurricane Harvey impacted the site during construction. Introduction The Fort Bend Grand Parkway Toll Road Authority (Owner) needed to protect the north bridge abutment with a retaining wall system due to rapidly eroding conditions of the Brazos River banks within the 300- feet-right-of-way of the State Highway 99 Jodie Stavinoha Bridge. The extent of the local scour and erosion along the north bank of the Brazos River has caused concern for the structural integrity of the bridge. The magnitude of the erosion along the north bank at the location of the bridge has been measured at about 120 feet over three recent hydrologic flood events locally referred to as Memorial Day 2015, Memorial Day 2016, and Tax Day 2016. During construction, a new record flood level occurred due to Hurricane Harvey in August of 2017 that resulted in a portion of the retaining wall needing to be redesigned due to even more erosion occurring. The Brazos River is an actively eroding and meandering alluvial river plain that naturally meanders and migrates over time. The processes of bank erosion and meander migration were ongoing before the bridge was constructed and will continue in the future. These recurring major flood events, however, rapidly increased the rate of erosion in just a few years. Background. Due to the need to protect the bridge as soon as possible, the Owner selected a project team consisting of the designer, general contractor and specialty deep foundation contractor prior to final design to work together in developing a cost-effective design that could be implemented rapidly. The project team initially considered both a secant pile and tangent pile retaining wall system using drilled shafts. After reviewing various alternative designs, a tangent pile wall with seal piles was selected based on both cost effectiveness and speed of installation. The tangent pile with seal pile option was approximately 20 percent lower in cost and 50 percent faster to install.

Jan 1, 2018

By Holmes R. J, Miles J. G

An on-stream shale detector has been developed that is suitable for use on conveyor belts carrying iron ore of up to 200 mm particle size. The shale is distinguished from high-grade iron ore by means of the substantially greater total natural gamma-ray activity (400-3000 keV) of the shale, which is due to the presence of uranium (214Bi), thorium (208TI) and potassium (40K). Other gangue materials, sueh as highly siliceous cherts and jaspilites, escape detection because of their low activity. A dynamic trial of the shale detector at Mt Whaleback, using a large-volume (100 × 100 400 mm long) "Polyscin" Nal(TI) gamma-ray detector, demonstrated that as little as 20 tonne of ore on a conveyor belt (equivalent to partial truckloads of ore) can readily be monitored for shale content.

Jan 1, 1981

By R. J. Schafer-Frentz, T. G. Joseph, M. Curley

"Greenhouse gas emissions—specifically of carbon dioxide—are a concern in Canada, where industrial sectors such as mining are stringently regulated for carbon release. Cumulative emissions are positively related to fuel consumption, which is controlled by several factors. This study investigates one of these factors: the product of vehicle speed and running surface total resistance (TR; sum of rolling resistance and grade resistance). Results show that TR directly affects fuel consumption and emissions—a relationship that is mathematically predictable. Fuel consumption and emissions, which are principally associated with the durability or deterioration of wearing course materials, were analyzed to aid selection of road construction capping material of low rolling resistance. In the oil sands region in the province of Alberta, ground conditions change seasonally. Therefore, the annual fuel consumption for the same wearing course material was also compared. Results demonstrated that haul truck size was a contributing factor, but vehicle speed and TR more strongly influenced fuel consumption and emissions. ¦ KEYWORDS Carbon dioxide, Emissions, Fuel consumption, Grade resistance (GR), Greenhouse gas (GHG), Haul truck, Rolling resistance (RR), Total resistance (TR) RÉSUMÉ Les émissions de gaz à effet de serre (GES), et particulièrement celles de dioxyde de carbone, sont un problème au Canada, où les secteurs industriels tels que l’exploitation minière sont rigoureusement réglementés pour leurs émissions de carbone. Les émissions cumulées sont indéniablement en lien avec la consommation de carburant, qui est contrôlée par plusieurs facteurs. Cette étude examine l’un de ces facteurs, à savoir le produit de la vitesse du véhicule et de la résistance totale de la surface de roulement (la résistance totale, ou RT, est la somme de la résistance au roulement et de la résistance due aux rampes). Les résultats montrent que la RT affecte directement la consommation de carburant et les émissions, un lien qui est mathématiquement prévisible. La consommation de carburant et les émissions, qui sont principalement associées à la durabilité ou la détérioration des matériaux composant la couche d’usure, ont été analysées afin de contribuer à la sélection de matériau de recouvrement pour la construction de routes ayant une faible résistance au roulement. Dans la région des sables bitumineux de l’Alberta, les conditions au niveau du sol changent à chaque saison. Ainsi, la consommation annuelle de carburant pour le même matériau composant la couche d’usure a aussi été comparée. Les résultats ont montré que, si la taille des camions de transport est un facteur déterminant, la vitesse des véhicules et la RT influencent davantage la consommation de carburant et les émissions. ¦ MOTS CLÉS camion de transport, consommation de carburant, dioxyde de carbone, émissions, gaz à effet de serre (GES), résistance au roulement, résistance due aux rampes, résistante totale (RT)INTRODUCTION In Canada and around the world, global climate change has become a topic of great concern and discussion. Pres-sure on world leaders to quickly reduce their carbon footprint is prevalent, prompting new standards and regulations in various industries, including mining and oil and gas. In 2017, the Government of Alberta implemented a carbon tax. The majority of mining activities in this province are truck-shovel operations, where a large fleet of ultra-class trucks is loaded by shovels. Ultra-class haul trucks, classified as those with a capacity of 218–363 tonnes (t), emit high levels of carbon as they travel to processing entry points and waste dumps as designated by the mine plan and mine dispatcher. Mined ore and waste is typically moved over two 12-hour shifts per day throughout the year."

Jan 1, 2019

By Mehrotra G. M, Frohberg M. G

Based on the concepts of statistical thermodynamics of athermal mixtures, an approach is developed which is capable of quantitatively explaining the thermodynamic properties of binary silicate systems. Expressions for the ionic fractions of various anionic linear and nonlinear chain polymers are derived. The developed expressions for free energy of mixing are tested by applying these to the system PbO-SiO2. The ionic fractions of various chain polymers in this system are calculated. The two cases, namely, of linear and nonlinear chain polymers are compared with each other.Limitations of earlier models are pointed out.

Jan 1, 1975

By P. A. Neill, O&apos

The caisson foundation for Vent Building No. 6, at the southern landfall of Boston's Third Harbor Tunnel, was installed inside an unbraced concrete cofferdam 250 feet in diameter and about 70 feet deep. As a spectacular engineering feat, the cofferdam itself certainly ranks first. However, the foundation work within was no routine caisson job and made its own contribution to the state of the art. Comprised of 5 ft. diameter caissons socketed 10 to 16 feet in sound rock, it posed serious challenges in logistics, space limitations and time, requiring development of unique, purpose-made equipment. The unexpected discovery of significant depths of shattered rock overlying acceptable sound rock, along with other surprises of lesser import, compounded the problems. How these challenges were planned for, met and overcome is the subject of this paper.

Jan 1, 1994

By Fanke Meng

Electrolyzing oxides of titanium, aluminum and niobium could prepare high-Nb bearing TiAl alloy (Ti-45Al-9Nb) at 1500°C. The chosen electrolysis voltage is 3.5V, which is lower than reducing voltage (~4.7V) of electrolyte CaF2, but higher than that of titanium, aluminum and niobium oxides. The investigation shows that compared with traditional methods, this method for preparing high-Nb bearing TiAl alloy is of many advantages such as few steps, friendly environment, low energy consumption, low cost and high current efficiency.

Jan 1, 2009

By Mark Maday

As part of the I-94 North-South Corridor reconstruction program, the Wisconsin Department of Transportation (department) is reconstructing the Mitchell Interchange in Milwaukee, Wisconsin. Located on the south side of Milwaukee near Mitchell International Airport, The Mitchell Interchange interconnects I-94, I-43 and I-894. Reconstruction began in 2009 with the letting of the first advance contract for local crossroad bridge reconstruction. A second advance contract for construction of collector-distributer roads on each side of the I-94 mainline was completed in 2010. The main contract involving reconstruction of the core of the Mitchell Interchange was let in the summer of 2010, and is scheduled to be completed by the end of 2012. The core contract includes construction of three cut and cover tunnels along two system interchange ramps. Construction of the three tunnel structures is on the critical construction path. The contract includes an interim contract completion date that requires the tunnels to be open to traffic by the end of 2011. A top down method of construction using drilled shaft secant piles for the sidewalls of the cut and cover tunnel structures was selected as the preferred structure type to address subsurface and construction schedule challenges. The department identified in pre bid coordination that no cost reduction incentives would be reviewed or accepted for changes in tunnel wall type. A major component of the tunnel structures requires the installation of 1,500, 4-foot diameter secant piles. This paper presents mitigation strategies to manage construction risks associated with the installation of the secant piles including; prequalification of the secant pile subcontractors, requirement for use of full depth temporary casing, a site specific quality control plan, specifying drilling equipment, and developing a geotechnical baseline report for this critical component of the Mitchell Interchange reconstruction project.

Jan 1, 2011

By Dean Nichols, Matt Ortel

Explosive accidents in the United States have brought increased attention to emergency operation plans (EOP) at all facilities that manufacture, transport, or store hazardous materials – particularly explosive materials. Explosions are sudden, powerful, and complex events that are difficult to characterize in terms of the thermal, over pressure, and debris effects. Industry, regulatory, and public officials require emergency response planners to not only anticipate the blast effects of an explosion, but also to prepare an appropriate response.

Jan 1, 2016

By P Cotton, N Cox

The Brisbane City Council has implemented a program of continual improvement at its Mount Coottha Quarry in the heart of Brisbane, Australia. The program has been underway for the past 6 years, and has resulted in very significant improvements in terms of both the cost effectiveness of its operation, and in terms of its environmental impact on nearby residents. The work has included a focus, amongst other things, on blasting efficiency and has challenged conventional thinking in terms of the size of blasts fired, the frequency of firing, the diameter of blastholes, and the use of bulk emulsion or slurry explosives.

Jan 1, 1996

By D. Nutakor

Rock joint stiffness is not only a poorly known parameter, but also has no established laboratory measurement procedure. This paper presents methods used to determine the normal and shear stiffnesses of healed joints filled with vapor-altered minerals obtained from the Yucca Mountain site in Nevada. Results show that these joints behave linearly up to 85% of their loading history and are stiff with strengths very close to the strength of the intact rock. Factors that might have contributed to the linear behavior of these joints are discussed and areas requiring further investigation are provided. Joint normal stiffness ranges from 7.16 to 64.77 GPa/mm with an average value of 26.93 GPa/mm, while joint shear stiffness averages 11.41 GPa/mm and ranges from 3.09 to 28.41 GPa/mm. Young?s modulus of the vapor-altered joint infilling was calculated from the stiffness of the healed joint. Young?s modulus of the vapor-altered joint filling material averages 7.89 GPa and ranges from 2.15 to 19.43 GPa. Given the pervasive presence of such altered rock, usually in the form of sub-spheroidal 3-D pockets, this property should be of value in any numerical modeling attempting to describe the mechanical behavior of these tuff formations at the level of detail where inclusions might be a factor.

Jan 1, 2008

New GSP Trade Status Approved.--President Carter, by Executive Order effective March 30, has approved Generalized System of Preference treatment for imports of nonferrous metal products and other imports from Ecuador, Indonesia, Zimbabwe, Uganda, and Venezuela. As of May 2, Afghanistan and Ethiopia will be taken off GSP status. Under the Generalized System of Preferences, certain imports from developing countries are provided duty-free treatment. A country can lose its GSP status if its shipments of the product exceed $41.9 million or more than 50% of total U.S. imports during the preceding year. However, the President can waive the 50% rule in cases where total U.S. imports of an item in 1979 were less than $1 million. Certain nonferrous imports from Mexico, Peru, Chile, and Zambia are already covered by GSP. Hearings April 10 on International Tin Agreement.--The Fifth International Tin Agreement of which the United States is a signatory, which entered into force on July 1, 1976, will expire on June 30, 1981. A negotiating conference for a Sixth International Tin Agreement will be held under auspices of the United Nations at Geneva from April 14 to May 16, 1980.

Jan 1, 1980

(Published by courtesy of the Great Boulder Pty. Gold Mines, Limited)1. INTRODUCTIONThe faults described in the following paper are of a somewhat unusual character, and have presented a serious problem both in the development and mining of many ore-bodies on the Eastern side of the Boulder Belt. They are mentioned only briefly in the literature of the field, but were observed by, both Stillwell (1)t and Gustafson (2), and have been studied by other geologists and operators in various parts of the "Belt." Their effect on the lodes of Hamilton Section, Great Boulder Mine, was described by King (3) in 1937, and, during recent years, they have been encountered in most of the Great Boulder workings extending east of the Boulder Dyke.Although this paper is based mainly on a study of faulting and development problems on the Great Boulder mine, the general conclusions reached may be applicable to the solution of similar faulting problems in other mines throughout the field.In order to arrive at a clear understanding of the somewhat complicated relationships which the east-dipping faults bear to the lode systems it will be necessary to give a brief outline of the salient geological and structural features of the "Belt" before proceeding to describe the faults themselves.2. GENERAL GEOLOGYThe most recent descriptions of the geology of Kalgoorlie are those by Stillwell (1) and Gustafson (2) and the reader is referred to these as representing the basis of current knowledge of the geology of the field.The Boulder Belt is comprised of a central core of altered quartz dolerite which is flanked on either side by fine grained greenstones and lavas, usually referred to as the calc schists. Down the centre of the quartz dolerite mass there is an infolded bed of slate (2, p. 105) which has been intruded in lit par lit fashion by albite porphyry; the composite body of slate and porphyry so formed is known as the "Boulder Dyke." Numerous smaller porphyry dykes intrude both the quartz dolerite and the calc schist; these vary in composition and range from chloritised hornblende porphyrites to albite porphyries.The whole of the rock assemblage has been subjected tG a considerable amount of folding, faulting, shearing and fracturing, the greater part of which took place before the formation of the lodes.

Jan 1, 1941

By Johnny Lyons-Baral, John Kemeny, Don Kraemer

Ground vibrations from blasting can result in the degradation and failure of rock and soil exposures, as well as damaging neighboring houses and buildings. At the same time, vibration provides an opportunity to regularly monitor the rock and soil exposures. If a geophone or accelerometer is attached to a rock block or wedge on a mine slope, for example, then blast vibrations will regularly “sound” the rock block and the resulting vibrations can be used to assess the stability of the rock mass in the neighborhood of the accelerometer, as well as monitoring the properties of the blast. This paper describes the development of a wireless sensor network based on inexpensive MEMS accelerometers for blast monitoring and rock and soil structural health monitoring. The wireless sensors are placed at various locations in and around an open pit mine or quarry, and transmit data to a central source after ground vibration events occur. As described in the paper, a variety of wireless and non-wireless accelerometers were tested in actual field conditions. This includes the monitoring of over 30 blasts at an open pit mine in Arizona with as many as nine simultaneous accelerometers. Matlab was used to process all the data and develop innovative methods to view and interpret the data. This includes the use of the wavelet transform to determine resonance frequencies, and the use of both ground resonance frequencies and scaled-distance peak particle velocity (ppv) relationships to assess slope stability. As part of this research, a three-dimensional point cloud environment for viewing and analyzing the vibration data from the sensors has also been developed.

Jan 1, 2014

By Hemingway P, Boag J

Major operating aspects of the Mary Kathleen Uranium Ltd. treatment plant are discussed with partkular reference to those which are peculiar to this operation.Problems associated with the production of a penalty free uranium oxide product are examined and the methods developed to overcome them are described in detail.INTRODUCTIONMary K,athleen Uranium Ltd. is the largest of the Australian uranium producers. The flow-sheet is based on fine grinding, standard sulphuric acid leach, ion exchange concentration, and magnesia precipitation of the final product, with certain modifications introduced as the result of pilot plant investigations at the South Australian Department of Mines Research Laboratories in Adelaide.The plant commenced operations in June, 1958, attained design tonnlige of 1,120 tons per day in September of that year and has since operated continuously with a throughput in excess of 1,000 tons per day. Pilot plant recommendations generally have been followed, and predicted results have been attained. The only exception has been the silica and rare earth content of the product produced during the early months of operation. Considerable modification of the early resin regeneration techniques resulted in the reduction of the silica content of the product to within specification limits. Research work in the ion exchange section has also resulted in the reduction of the rare earth content of the product to below specification levels. All product now being produced is completely within the agreed specification limits of impurities.

Jan 1, 1961

By Y. Q. Zhang, Y. Luo, S. S. Peng, C. T. Holland

Barrier pillars in underground coal mines could eventually be subjected to a hydraulic pressure head due to the build-up of mine water in the old workings. The pressure head could not only act as a force to destabilize the pillar but also cause seepage flow through the pillar and its surrounding strata. Excessive seepage flow could induce piping failure that in turn could accelerate the mechanical failure process of the barrier pillars. In this paper, finite element simulation approach has been employed in the evaluation of the barrier pillars. Both the stress distribution and the seepage flow pattern in and around a barrier pillar have been simulated numerically. The effects of ground stress on rock permeability to water seepage has been taken into consideration in these simulations.

Jan 1, 2001