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By Otto Sandovel Zea

El compromiso de minería perfecta se limita no solo a la preservación del medio ambiente, sino a la prevención de riesgos por desprendimiento de rocas y aplastamiento en el interior de la mina. En ese sentido, el presente texto señala la factibilidad de minar a sección plena todos los tajeos a través de la simulación de las condiciones más favorables y desfavorables de la mina, determinando como la alternativa más viable la bóveda en arco. Dicha estructura otorga estabilidad a las labores de minado -en tanto da sostenimiento activo a través del (Shotcrete SFR y Pernos Hydrabolt), así como desarrolla mayor productividad y menores niveles de riesgo por desprendimiento de rocas, menores grados de sobre excavación y genera de vibraciones al haber implementado la voladura de Pre-corte en sus labores.

Sep 12, 2011

By Verya Nasri

The use of a single tunnel boring machine (TBM) tunnel of approximately 12 to 13 m (40 ft to 43 ft) diameter for transit systems to house both light rail or subway tracks in a stacked configuration is an advanced concept that allows significant savings in construction cost and time while reducing, to a large extent, the negative effects on the environment. This solution, similar to the recently completed Barcelona Metro Line 9, integrates station platforms, train storages, crossovers, bypass tracks, ancillary areas and utility corridors inside a single tunnel. Each of the underground stations consist of a cut-and-cover entrance structure and ventilation shafts, that also serve as emergency exits. The excavations for the station structures and shafts can be done on one side of the street with nominal impact on traffic and utilities.

Jan 1, 2010

By John R. Wolosick

MACROPILES are defined as ultra-high-capacity micropiles, with working loads in excess of 250 tons. The piles are typically 9-5/8 to 24 inch (244 to 610 mm) outside diameter. They are drilled and grouted in place, with either large diameter steel bars and/or steel pipe reinforcement. The piles are typically tested to twice the working load. Piles with working capacities of up to 500 tons and tested to 1000 tons have been installed. The paper discusses MACROPILE design philosophy, construction techniques, and two case histories where this innovative foundation system has been installed. Macropiles are descended from micropile technology pioneered in the early 1950s by Fernando Lizzi of Italy.

Jan 1, 2006

By John Vynne

Too often, a mine’s operations, including drilling, blasting, loading, hauling, crushing, processing, etc., are considered independent steps, rather then a continuous process. In fact, these are interdependent operations with each step in the process having an impact on subsequent operations. If the effectiveness of the drilling and blasting operations can be improved, they will impact the entire mining process. Some of the resulting improvements include: level benches on grade; fragmentation and diggability with the result being reduced loading times; haul cycles improvements; and the crushing and milling operations will be more efficient and less energy consumed. Thunderbird refers to this as “Drill to Mill” information cycle or process. This paper focuses on two of the technological enhancements Thunderbird has added to its drill monitors that allow the mines to impact the “Drill to Mill” concept. These enhancements are: incorporating global positioning satellites into drill monitors; and radio off-loading of data.

Jan 1, 2001

By William O. Vanderburg

This report 3/gives the results of a reconnaissance of the mining districts in Lander County, Nev., made from March 29 to April 20 and from May 9 to May 21, 1938, during which virtually all of the mining districts n the county were visited. No attempt has been made to include in this report all the mines and prospects in the various mining districts, and it should be stated that whether or not a property is mentioned herein has no. bearing on its merits. The report rovers the situation of the various districts, types of ore deposits, ownership and description of mines and prospects, information on past and current activity, and other information of economic interest likely to be useful to those interested in the development of our mineral resources. The names of the various districts mentioned are those generally used when they were organized for purposes of record and regulation. When originally organized, the districts embraced large areas with no well-defined boundaries, so that the names have little geographical significance.

Jan 1, 1939

By Raymond J. Castelli

The paper provides a general overview of the numerous types of earth retaining systems currently available, and organizes these various systems by several classification methods. These classifications can be used as a guide in identifying the appropriate type wall or walls for any specific project application. As a further aid in sorting through the numerous wall alternatives for a specific design or construction project application, the paper suggests a systematic approach for wall selection, and presents helpful charts summarizing the general advantages and disadvantages, and typical limitations for the currently available wall systems.

Jan 1, 2003

By Olli Aulio, Outokumpu Oy

"GENERALThe Outokumpu Company is today an important European producer of metals from its own mines: copper nickel cobalt, ferro chrome and zinc being the main products. In 1972 about 4 million tons of ore was hoisted from eleven mines.Outokumpu Oy has gained experiences on the various aspects of on line computer control since 1968. This knowledge has been combined to develop a standard computer control package for concentrator control. Before the development of computer control package was started Outokumpu Oy had three large computer control systems. The first system was at the Pyhasalmi Concentrator, thee second at the LokkolaPlant, and the installation of the third system at the Vuonos Concentrator was just started.The characteristics of general computer software packages - both control and executive ones - were thus well-known as well as the practical usage of control theory. Furthermore Outokumpu had developed the Courier analyzer which included a so-called minicomputer. This project had given experience both 1n totally self made real tire executives and in computer hardware and peripheral d=vices. The instrumentation of the Outokumpu concentrators was designed and installed traditionally by the engineers of Outokumpu themselves."

Jan 1, 1973

By Milner A, Brockway D, Hodges S

The combustion of brown coals in Latrobe Valley power stations produces approximately 500 000 tonnes of solid wastes each year. This material, which includes precipitator ash, char and furnace ash, is hydraulically sluiced to large ashing ponds and the supernatant solution is ultimately discharged to the sea. There are significant operational and capital costs associated with the current ashing system. The ash produced from the Latrobe Valley coals is unique and has a wide variety of potential applications including soil conditioning, concrete and cement extenders, fillers in non-metallic materials, components of building products. In addition, with the application of appropriate technology, it is possible to extract char, sodium sulphate, calcium carbonate and magnesium metal (as the chloride) in substantial quantities from the ash. Research has been carried out to explore the prospects of these various options for ash utilisation. The research has focused on detailed characterisation of the ash material and the potential extraction efficiency for various species under various conditions. From this work a conceptual process has been developed and subsequent studies have been directed towards understanding variables and optimising operating regimes for product extraction. Currently, the work is concentrating on the separation of char, the development of high-grade carbon products and the extraction of sodium sulphate.

Jan 1, 1992

By R. F. Rolsten

VAN Arkel 1 prepared ductile tantalum by the thermal decompoiition of tantalum pentachloride on a resistively heated wire (2000° C) in an evacuated bulb maintained at 100°C. Burgers and Basart2'3 observed the formation of a mixture of tantalum carbide and free metal when a carbon deposition base was used. campbel14 suggested the thermal decomposition of the iodide if a lower decomposition tem- perature was desired. To date, the details for preparing high-purity iodide tantalum have not been disclosed. EXPERIMENTAL The tantalum to be purified was symmetrically placed around the clear quartz deposition surface centrally located within a 64 mm cylindrical Vycor bulb. The deposition vessel usually employed5 was modified6 by incorporating a reentrant fin,mer in place of the customary metal filament in the head

Jan 1, 1960

By Jamal Rostami, Ebrahim Farrokh

Selection of tunneling method, specially the use of shielded machines for application in deep rock tunnels can be heavily impacted by presence of ground convergence and squeezing conditions. Tunnel convergence is a function of ground conditions (i.e., rock mass behavior, groundwater, in-situ stresses), size of the opening, and TBM operational parameters. The case study of Ghomroud water conveyance tunnel project in Central Iran, which is under construction using a double shield TBM, is used to examine the effect of rock parameters on tunnel convergence and hence on the need for over excavation and shield lubrication to avoid problems with the shield getting stuck. Although it is impractical to perform a continuous assessment of rock mass conditions within the shield or in the lined tunnel, results of field observations and subsequent studies show that the amount of the tunnel convergence has direct correlation with the percentage of fines and large rock fragments in the muck and TBM thrust/torque/ROP. These relationships have been examined and will be presented in this paper.

Jan 1, 2007

By Sumner M. Anderson

Any discussion of outside support to Latin American mineral industries must concede at once the pre-eminent role of U. S. industry and business. American capital has developed the great copper resources of Chile and Peru, the lead-zinc of Peru and Mexico, the bauxite of Surinam and Jamaica, the petroleum and iron ore of Venezuela. American consumers have provided the market for their products. U. S. companies operating south of the border have trained Latin American geologists, engineers, chemists, and skilled labor—including metal, mineral, and fuel technicians—to new and greater competence. The industrial demands of World War II drastically altered world economics and concepts of U. S. foreign mineral requirements. In this country discovery of vital mineral resources fell far behind the alarming depletion rates, and there was new appreciation of the actual and potential importance of the world's less extensively explored areas. During the war and afterward, the task of supplying the nation's mineral requirements became greater than private industry could carry alone, and the Government assumed a position of continuing support. In Latin America, as elsewhere, this support applies in three categories: banking, procurement, and technical assistance. The first two are now generally accepted as necessary Government functions; the third has often been misunderstood and misinterpreted, although it has given rise to legitimate controversy. There have been major accomplishments in all three categories, as well as some errors of judgment. Since the beginning of World War 11, U. S. Government financing, procurement, and technical assistance have been applied on a large scale to a wide range of commodities and services throughout the free world. The present discussion—under the separate headings mentioned—will concern only the support related to a single industrial group in a single geographic area. During the War Federal banking was conducted on an emergency scale by temporary agencies created to meet the abnormal circumstances. Unfortunately, there are no readily available data on these activities that would permit evaluating loans and credits extended for mineral projects in Latin America. The only agency operating in this field since World War II is the Export-Import Bank, under its own authority and to some extent from credits authorized by the Office of Defense Mobilization. The Bank can offer more capital—on more favorable terms—than is available from most Latin American banks, and its staff of engineers evidently can appraise loan applications more favorably than commercial banks in this country are willing to do. The risks seem to be justified, as defaults have been well under 1 pct of total loans. From V-J day 1945 to the end of 1957, mineral loans to Latin America have been authorized for projects totaling $541.63 million in eight countries. In order of magnitude of credits, they have been made to Brazil, Peru, Chile, Mexico, Argentina, Venezuela, Guatemala, and Bolivia. In order of magnitude by industries. they are for development and expansion of steel mills, copper, manganese, nitrate plants, iron ore, zinc plants, sulfur plants, cement plants, tungsten, coal, and lead. Loan Distribution: By far the largest loans have been $307.9 million for iron and steel projects in Brazil, Chile, Mexico, Argentina, and Peru: $100.4 for developing the great low-grade copper deposits of southern Peru; and $55.3 million for developing manganese deposits in the Territory of Amapa, Brazil. Others range from $20.8 million for a zinc smelter in central Peru to $19 thousand for iron-mine trucking equipment in Chile. It has been noted that 59 pct of the loans have been to foreign companies, 14 pct to companies of mixed foreign and American capital, and 27 pct to American mining companies. About 40 pct of the total authorizations has been disbursed so far. In addition to these amounts, the Strategic Materials Division of the Economic Cooperation Admin-

Jan 1, 1959

By T. P. Williams, M. B. Rydzewski, B. Corner

Konkola Copper Mines (KCM) plc is an integrated copper producer operating on the Copperbelt in Zambia. KCM has numerous mining operations located in the towns of Chililabombwe (Konkola Mine), Chingola (Nchanga Open Pit and Underground operations), Lusaka (Nampundwe Mine), with a smelter located in Kitwe (Nkana Smelter) and an SX-EW plant in Chingola (Nchanga Tailings Leach Plant). [ ]

Jan 1, 2005

Flat jack stress determinations in selected colliery roadways have revealed a range of measured stress from 330 lb/sq. in. tension to 3,750 lb/sq. in. compression. Photoelastic examination of loaded plastic and actual rock model mine openings has shown that the primary horizontal stress required to attain these measured stresses would be from one to three times the superincumbent vertical load.Examination of roof movement with a borehole extensometer and a series of anchors at various horizons to 30 feet in a vertical roof borehole showed that when a standing face was advanced the roof movement was practically confined to the lower two feet. The majority of this movement occurred during the 36 hours after mining at this face commenced.The use of a radioactive isotope and a scintillation counter in a pair of parallel boreholes is a sensitive and accurate method of roof bedding plane crack detection.INTRODUCTIONA knowledge of strata stresses is required to understand the deformation of an underground opening and, in particular, the roof behaviour. It is the aim of investigations currently being conducted by Australian Coal Association (Research) Ltd. to determine the stress existing around mine openings and the location and magnitude of roof movement.STRATA PRESSURE MEASUREMENTMost measurements of strata stress are performed at the surface of underground openings and the majority measure the change of strain resulting from stress relief. The accuracy of the measured value of stress depends upon knowledge of the rock modulus of elasticity. The flat jack method has the advantage that strain relief is restored by a measured stress applied directly by the jack. The rock modulus of elasticity can also be determined.

Jan 1, 1963

By F. M. McEvoy, E. J. Steadman, R. Murfin

In England, the provision of aggregate is determined by the historical relationship between construction and aggregate consumption. This approach does not necessarily lead to sustainable decision-making and can be seen as being driven by political expediency, rather than reasonable environmental consideration. The introduction of the statutory requirement for Strategic Environmental Assessment (SEA) in the UK has provided the opportunity to examine this issue on a more rational basis. This paper provides a practical application of a SEA based approach, to the provision of aggregates at a regional level. The process, underpinned by relevant information on resources and environmental assets, suggests that alternative supply scenarios for aggregate provision are tested in a transparent, consistent manner with increased genuine stakeholder consultation. It supports a move away from "predict and provide" approaches to one where aggregates are sourced with the best balance of environmental costs and benefits.

Jan 1, 2005

By L. Lacerda

Spray-on ground support membranes (GSM) or thin support liners hold today perhaps as much potential to impact underground (u/g) ground support operations as dry and later wet-mix shotcrete when introduced to mining in the latter part of the 20th century. This emerging technology has come a long way from the time the first single component experimental coatings were tested in the mid-1980s. Due to a number of factors, including occupational health risk and mine safety regulations, it has taken quite some time for the development of non-hazardous membrane products. However, at this junction most existing u/g mines that employ more conventional forms of ground support could benefit from evaluating GSM technology as a means of improving safety and the bottom line. The same is especially true for future mine developments. This paper describes Master Builders Inc.’s CS1251 GSM product and its implementation. It discusses the situations in which GSM may replace other forms of ground support. Furthermore, it evaluates GSM costs & safety issues and looks at present applications and the potentially bright future of this technology.

Jan 1, 2002

By Valérie Tremblay

Plan de la presentation ?Laboratoire d?analyse des fluids ?Gestion des contaminants ?Condition Monitoring Avantages reliés aux analyses ?En savoir plus!! ?pour minimiser les coûts d?opération; ?pour prévenir les défaillances catastrophiques; ?pour maximiser le rendement des équipements; ?pour maximiser la longévitédes équipements; ?pour permettre des périodes d?entretien planifié.

Feb 1, 2008

By William R. Yernberg

SME’s Arizona Conference was held at the Doubletree Hotel at Reid Park in Tucson on Dec. 5and 6, 2004. The annual conference is organized by the Arizona Conference Board of Directors, which represents SME sections in Arizona and adjacent areas. The conference provides an opportunity for individuals and corporations associated with mining in the region to get together each year to discuss the status of the industry. The meeting featured a keynote address and more than30 technical papers. Two years ago, the U.S. copper industry was facing on a run for two years now,” and “both precious metal and base metal prices are going up.” The increases in metal prices were attributed to development in China and other Asian countries. “With a population of 1.6 billion, China has recently created 80 million jobs,” said Silver.

Jan 1, 2005

By Mark K. Larson

Researchers at the National Institute for Occupational Safety and Health?s (NIOSH) Spokane Research Laboratory are developing a borehole profilometer to dynamically measure the roughness pro-file of boreholes used to install roof bolts fully encapsulated with resin. Numerical measures of roughness were calculated from profiles of borehole surface roughness to determine potential roof bolt anchorage capacity. The concept of dynamically profiling was proven through the following series of laboratory tests: a sensitiv-ity test using various grits of sandpaper, a known-profile test along a section of a concrete hole, and a simulated borehole test in a pipe with machined grooves. Two profilometer prototypes were devel-oped that measure slight changes in the radius of a borehole using either strain-gauged, spring-steel arms or rigid, steel arms attached to a spring-loaded cone and a linear potentiometer. Both instruments performed reasonably well in the laboratory and were subsequently tested in boreholes drilled in two concrete blocks using different drilling techniques to obtain three different borehole surface roughnesses. A Z2 roughness parameter was calculated with data from the first profilometer, and an average radial increment was calculated from the test results of the second profilometer. Although both instruments were able to readily distinguish the difference between smooth and rough boreholes, the correlation coefficient (r2) for a linear relationship between Z2 and average radial increment was 0.577. Pull tests were conducted with resin bolts installed in the concrete blocks, but maximum pull-out strength could not be correlated to borehole roughness because in each of these tests, failure occurred at the resin-bolt interface. A more sophisticated prototype has been designed to measure surface roughness and also accurately determine the location and tilt of the instrument in the borehole. However, this instrument has not yet been fabricated or tested.

Jan 1, 2007

By Paul S. Goodman

This report examines the feasibility of Employee Assistance Plans for the coal industry. Three issues are examined in detail. First, the prevalence of off-the-job factors such as alcoholism, drug abuse, and marital problems are examined in a sample of miners from the eastern, midwestern, and western underground coal fields. Then data were presented that examined the link between these off-the-job factors and behaviors critical to the mines such as absenteeism and turnover. Lastly, we examined the effectiveness of the major Employee Assistance Program in underground coal mining--the HELP Program. The report contains recommendations on whether coal mining companies should implement these programs and how these programs should be designed.

Jan 1, 1986

By Thomas Leonard Watson

Jan 1, 1906