Search Documents

By Jamie Bonner, Ray Hutton, Taro Nonaka

The Nancy Creek Tunnel is a deep tunnel, designed to store and convey wastewater by diverting flows from trunk sewers currently at or near capacity in the northwest of the City of Atlanta. The tunnel, constructed in hard rock, has an overall length of 13,300 m (43,700 ft), and a finished diameter of 4.9 m (16 ft). The project is currently under construction by a joint venture of Obayashi/CJB for the City’s Department of Watershed Management. This paper describes the contractor’s techniques and equipment, as well as discussing challenges which were overcome. The project is scheduled to be complete in October 2005.

Jan 1, 2005

Coal preparation plant simulators are used to study flowsheet alternatives and determine product quality and quantity that can be produced under various operating conditions for individual circuits. Some simulators also provide an estimate of the cost per ton of clean coal by determining the number and size of different processing units required for a specific raw coal tonnage and by computing both capital and operating costs for individual units. However, to the authors? knowledge, none of these simulators have the ability to optimize plant performance while satisfying multiple product quality constraints and selecting the most profitable flowsheet from many alternatives. A novel coal preparation plant simulator (SIU-Sim) that maximizes the overall plant yield using a robust optimization tool and selects the best plant cleaning circuit configuration based on maximum plant profitability is presented. The simulator also identifies the best operating conditions for individual circuits of a plant to satisfy multiple quality constraints for the overall clean coal product. It uses a genetic algorithms- (GA) based technique to maximize the overall plant yield for each cleaning flowsheet alternative and uses a net present value (NPV) analysis technique to maximize plant profitability for the entire life of a new plant or the remaining life of an existing plant. The step-by-step development of the simulator along with a case study demonstrating its specific features is presented.

Jan 1, 2008

By Shemek Oginski, MARK C. JOHNSON

All Rights Reserved. Printed in the United States of America. Information contained in this work has been obtained by SME, Inc. from sources believed to be reliable. However, neither SME nor its authors guarantee the accuracy or completeness of any information published herein, and neither SME nor its authors shall be responsible for any errors, omissions, or damages arising out of use of this information. This work is published with the understanding that SME and its authors are supplying information but are not attempting to render engineering or other professional services. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Any statement or views presented here are those of individual authors and are not necessarily those of the SME. The mention of trade names for commercial products does not imply the approval or endorsement of SME.

Dec 1, 2015

By T. W. Beck

Overexposure to respirable dust remains a widespread health hazard to roof bolter occupations in underground coal mines. Recently implemented mist drilling technology was evaluated for its effectiveness in controlling respirable dust exposures for roof bolting personnel. This work presents the findings from NIOSH field and laboratory studies comparing respirable dust levels on mist drilling roof bolter machines to dust levels measured on machines using a conventional vacuum drilling system. Gravimetric and instantaneous respirable dust samples were collected for multiple drilling cycles. These dust measurements were used to assess the potential dust control capabilities relative to conventional drilling. Controlled laboratory tests found 0.3 mg/m3 more respirable dust with mist drilling than with the conventional vacuum method. A separate field investigation of the two techniques observed higher dust levels around the mist bolting machine.

Jan 1, 2008

By D. R. Wilburn

This summary of international mineral exploration activities for 2008 draws upon available information from industry sources, published literature and U.S. Geological Survey (USGS) specialists. The summary provides data on exploration budgets by region and mineral commodity, identifies significant mineral discoveries and areas of mineral exploration, discusses government programs affecting the mineral exploration industry, and presents analyses of exploration activities by the mineral industry based upon these data. Two types of information are reported and analyzed in this annual review of international exploration for 2008: 1) budgetary statistics expressed in U.S. nominal dollars provided by Metals Economics Group (MEG) of Halifax, Nova Scotia (Metals Economics Group, 2008a, b), and 2) information on regional and site-specific exploration activities that took place in 2008 and compiled by the USGS. The MEG information summarizes planned company budgets for worldwide exploration activities in 2008, primarily for precious metals (gold, platinum-group metals and silver) and base metals (copper, lead, nickel and zinc). MEG includes information on additional mineral commodities only where it is available. Information on uranium exploration was included in the MEG overview for the first time in 2007, although this information was not included in the USGS analysis. The MEG survey methodology was changed in 1999 to include companies with exploration budgets between $100,000 and $2.9 million, as well as those companies included in prior studies whose anticipated budgets were above $2.9 million. MEG estimates that its post-1999 surveys cover at least 90 percent of world nonferrous nonfuel mineral exploration budgets. The 2008 survey is reported by MEG to cover an estimated 95 percent. Companies that chose not to participate in the MEG study, private companies that do not publish data, and government-funded exploration activities make up the majority of the remaining 5 percent. MEG included 91 more companies in its 2008 survey than it did in 2007 USGS compilations of site data described here primarily include nonfuel minerals, with an emphasis on base metals, diamond and precious metals. Analyses are based on information provided by USGS mineral commodity and country specialists and by other USGS scientists, as well as industry contacts and trade journals.

Jan 1, 2009

By Grant P. Cordon

Our subject, "Safety, Legal, and Contracting," is a range of topics which covers a broad spectrum, but is obviously Intended to focus our attention upon certain particular aspects of tunnel problems. These are all fascinating and complex subjects, and others are much more qualified to discuss to discuss the fine points involved. Put after some 45 years' involvement as an inspector, engineer, contracting officer, and especially for the last 22 years as a contractor's estimator and manager, I have developed some strong and definite convictions to share with you. I hope it will serve to get you started thinking. My first tunnel experience was in a soft ground tunnel which was dug by hand, literally. The crown or arch back was taken out, a pebble at a time, by bare hand. The face was constantly breast-boarded, and the mucking was all done by hand shovel. My first rock tunnel was drilled by hand held drifters from the muck pile. Since then, most tunneling techniques have improved greatly. The jumbos, booms, muckers, and moles have taken over many of the back-breaking chores, and reduced the manpower requirements.

Jan 1, 1974

By J. G. Davis

The St. Peter Sandstone is typically a well-sorted, friable, ultra-pure, fine- to medium-grained, quartzose sandstone with silica content higher than 99 weight percent in places. The sand grains are well-rounded, highly spherical and characteristically frosted. Their size typically varies from 2 millimeters diameter (No. 10 U.S. Standard Sieve Series size) to less than 0.08 millimeters diameter (No. 200 U.S. Standard Sieve Series size). A freshly exposed surface of the formation is commonly white with shades of pink and green. Weathered surfaces are a dirty gray or brown and are case-hardened at many localities. Bedding is characteristically indistinct, and the formation usually appears massive throughout. The rock is cross-bedded and ripple-marked locally. The formation is generally porous, permeable and rarely fossiliferous in Missouri. The St. Peter is continuously present in the subsurface in the northern half of the state and along the southeastern edge of the state. The St. Peter crops out in a narrow band that starts in western Montgomery County and runs southeastward, along the Missouri River, to just west of St. Louis and continues south, just west of the Mississippi River, through Scott County. The outcrop belt varies from less than one mile wide to over ten miles wide, and it is over 150 miles in length. The formation dips into the subsurface radially away from the outcrop band. A notable isolated outcrop occurs in Lincoln County to the north of the main outcrop band. The St. Peter is discontinuously present in the subsurface along a band in the west-central portion of the state. It is not present at the surface or in subsurface in the remainder of the state. The formation averages 80?100 feet thick. There is an estimated 3.8 trillion short tons of St. Peter in Missouri. Sieve analyses on drill cuttings indicate three subsurface locations in northeastern Missouri where the St. Peter is greater than 10 percent by weight of sand falling in the 20?40 U.S. Standard Sieve Series size range. The St. Peter was first produced in Missouri in the 1870s for the manufacture of glass. Since that time it has been used as a paint additive, filler material, polishing compound, filtering media, and recently it is commonly used as a fracture proppant in oil and gas wells. The St. Peter is currently quarried and produced in Missouri from four sites located in St. Louis, Jefferson and Perry counties. In the same area there are at least nine abandoned historic mine sites.

Feb 27, 2013

By Ronald E. Heuer, Debra L. Virgens

INTRODUCTION Behavior of clay soils in response to tunneling is reasonably well understood by reference to the tunnel stability factor NT = Pz/su (Peck, 1969; Heuer, 1974). With this analysis tool, care must be taken to use a value of clay shear strength which represents the actual mass strength, considering such factors as slickensided fissures often found in stiff and hard clays. Behavior of clean sand and gravel soils is also reasonably well understood. Above the water table these soils must be assumed to act as running ground unless they are known to have significant cementation or have a very dense and angular interlocked grain structure. Below the water table they must be tunneled using some form of groundwater control such as dewatering, grouting, freezing, or internal fluid pressure in the tunnel such as compressed air or a slurry tunneling machine. The internal fluid pressure must approximately balance the external water head. Without such precautions these soils behave as flowing ground and may yield large volumes of water flow into the tunnel. A wide range of very fine sand, silty sand, cohesionless silt, and clayey sand soils exist in nature in a variety of geologic environments. The behavior of these soils in response to tunneling, and guidelines for anticipating their behavior, are not well described in the literature. Because of their content of fine particles, these materials may behave as if they initially have appreciable cohesion and moderate to low permeability. They may exhibit significant standup time, and require tunnel internal fluid pressure (compressed air or slurry pressure) less than the full external water head. It is important to be able to estimate the behavior of these soils when planning construction methods. For example, if the external water pressure is 140 kPa (20 psi), but soil stability at the tunnel face can be achieved as a compressed air pressure of 80 kPa (12 psi), a large cost savings may result.

Jan 1, 1987

By Robert S. Hendricks

LOCATION AND HISTORY The Lakeshore Copper property is located on the Papago Indian Reservation approximately 30 miles South of Casa Grande, Arizona. This major porphyry type deposit was discovered by El Paso Natural Gas Company in 1966. Following an extensive diamond drilling program, El Paso invited several mining companies, including Hecla, to examine the property with a view towards participation. Hecla's examination, and the attendant feasibility studies, led to agreements, which were finalized in September 1969, whereby Hecla would acquire a 50% interest in the property, and would act as operator. The Lakeshore deposit covers an area approximately 3,000 feet in width by 6,000 feet in length. It consists of an upper zone of disseminated copper oxides, averaging approximately 100' in thickness overlying a zone of disseminated copper sulfides up to 1,000 feet thick. Near the base of the disseminated ore is a blanket like zone of high grade copper sulfides, referred to as the tactite ore body. The mine is being developed to produce approximately 6,500 tons per day of oxide ore and 9,000 tons per day of sulfide ore. This represents a total daily production rate of 15,500 tons per day, which will be achieved by underground mining methods using rubbertired dieselpowered mining equipment. DEVELOPMENT LAYOUT The mine is being developed by two parallel 15° decline tunnels. The declines were collared 5,000 feet southeast of the ore body, and are being driven in a northwestery direction, to pass beneath the tactite ore zone. The declines will constitute the primary means of access to the underground workings. One decline (north

Jan 1, 1997

By D. R. Wilburn

This summary of international mineral exploration activities for 2006 draws upon avail-able information from literature, industry and U.S. Geological Survey (USGS) specialists. The summary provides data on exploration budgets by region and mineral commodity, identifies significant mineral discoveries and areas of mineral exploration, discusses government programs affecting the mineral exploration industry and presents analysis of the mineral industry based upon these data. Two types of information are reported and analyzed in this annual review. They include budgetary statistics provided by Metals Economics Group (MEG) of Halifax, Nova Scotia, and information on regional and site-specific exploration activities that took place in 2006 compiled by the USGS.

Jan 1, 2007

By N. Loganathan, Tan Boon Tee, Joe O’Carroll, Richard Flanagan

In recent years, tunnelling activities in Singapore have increased considerably with the construction of extensions to the existing sub-surface transport system, a deep tunnel sewerage disposal system, and tunnels for the laying power cables and other utilities. These tunnels are excavated through urban areas, adjacent to high-rise buildings, depressed road structures, beneath other tunnels, and buried services. Earth pressure balance (EPB) tunnel boring machines (TBM) have been used extensively in Singapore with great success. The risk associated with soft ground tunnelling, including tunnelling through Old Alluvium, can be minimized with an understanding of the geology, geotechnical parameters, and the tunnelling-induced behaviour of Old Alluvium (OA The purpose of this paper is to present some design and construction aspects of EPB TBM tunnelling through Old Alluvium.

Jan 1, 2005

By W. H. Schiffbauer

The protection of miners, equipment, and infrastructure is discussed. While the primary focus of the described technology is to prevent miners from being injured, struck-by, or crushed by heavy equipment; another major benefit realized is also the protection of equipment and infrastructure. An attempt is made to define and classify the systems used to provide proximity detection and warnings as well as collision detection and avoidance. Information about the speed of vehicles and human operator response time can be a factor in the choice of what type of system and what features are needed to properly address the needs. How the technology adjusts to compensate for various vehicle speeds, while maintaining the same level of protection is noted. The statistics which justify the need of miner protection are provided. The primary system components required, what attributes they feature, and how they respond in the environment, is briefly highlighted. The physics behind the danger zone marker technology and what makes it so robust and reliable is established. Examples of a few mining applications and specific operational modes are provided for both surface and underground.

Jan 1, 2011

By S. A. G. Poppen, M. B. Mirza, A. I. Cooley

The U.S. Department of Energy (DOE) is responsible for siting and constructing a licensed geologic repository for commercially generated high-level nuclear waste. Within DOE, the Office of Civilian Radioactive Waste Management (OCRWM) Program has this responsibility. To accomplish this mission, the OCRWM Program is engaged in a multidisciplined effort to identify, qualify, and develop repository sites. The current strategy of the OCRWM Program is to identify candidate repository sites in basalt, tuff, and salt and to develop exploratory shafts at those sites. Within OCRWM, the Salt Repository Project Office (SRPO) identified the salt site for the development of exploratory shafts. The proposed Exploratory Shaft Facility (ESF) in salt will have several primary purposes. The shafts will provide access to the reference repository horizon to permit in situ testing of the salt horizons in order to satisfy the following data acquisition needs: • Verification of the salt repository design parameters and validation of performance assessment models • Demonstration of the constructibility • Capability to adequately seal penetrations into the salt An exploratory shaft is required by 10 CFR Part 60 for the conduct of in situ testing at depth prior to submittal of a license application for construction authorization of a repository. Therefore, construction of an ESF will also facilitate the licensing process.

Jan 1, 1987

By Ivan Weber

Asking the question, “What do the world’s leading corporations and cutting-edge practitioners of sustainability put forth to guide a given mine site for planning and action toward ‘sustainability’?”, this paper explores the spectrum of methodologies and mindsets in available literature, then constructs an example for the large near-closure facility at Kennecott Utah Copper. Values, opportunities and constraints spring from physical, unutilized byproducts, from critical ecosystems and wildlife populations, from location relative to those ecosystems and proximate communities, and from the political will to perform adequate feasibility investigations. Patience, determination and thoroughness are imperative. Identifying most productive and, simultaneously, most protective and restorative, practical methods to approach ‘sustainability’ has become a central mission of industry and business, worldwide. A survey of recent international initiatives finds no single approach that establishes either a readily adaptable methodology or an appropriate set of ‘attention’ points, or agenda, to guide individual mining operations at specific locations toward the elusive but essential goal of ‘sustainable’ mining. Untying this convoluted knot of contending factors requires willingness to recognize and work within ecological constraints for community long-term needs. Occasionally, the task requires the sword of Alexander the Great. Through integration that is unflinchingly honest ethically, culturally, economically, ecologically and scientifically, fully cognizant of place and community at whatever scales are of greatest significance, and integrative of both problem-response and opportunity, we may envision a mineral extraction and beneficiation future that achieves the best, most nearly sustainable, results possible. Industrial ecology (IE), with its clear emphasis on community, ecosystems, and sustainable economic stimulation, presents a sufficiently broad and adaptable discipline to facilitate planning and management toward sustainable mining. The creation of sustainable jobs encapsulates IE’s analogy to the niche survival strategies of organisms in nature. Open to common-sense recognition of faults and opportunities at appropriate scales, IE is less a discipline or prescribed methodology than a mindset, willing to be rigorously scientific when science is imperative, but also willing to exercise “art” when creativity or community engagement are needed. IE is also capable of future-looking compassion for peoples and nature. Looking beyond what has occurred to date, the case of Kennecott Utah Copper provides ample illustration of possibilities for community economic development, environmental management, and significant initiatives beneficial at regional and planetary scales, to become recognizable as deserving of the label, ‘sustainable.’ Through what this researcher terms “whole mine, whole region, whole planet” thinking, strategies become visible and subject to serious consideration, presenting a path to best possible accomplishment in mining. Constituting a maximal broadening of mining’s “traditional” scope, the integrative approach proposed here is the ‘paradigm shift’ being made by many other industries around the world. In aggregate, these steps are the only hope for avoidance of environmental, social and economic risks that threaten to curtail resource development and impair mining companies’ ‘social license to operate.’

Jan 1, 2005

Multilevel-multiseam hardcoal mines on the European continent usually consist of a huge network of underground openings, sometimes more than 200 km long in total, with some longwalls operating down to a depth of 1,500 m. While operating several longwalls simultaneously, these mines are making use of a number of stationary and mobile measurement- and analysis units in their main ventilation passes combined with atmospheric measurements on the surface. This paper provides an overview over the systems and technology used and describes the typical set-up of a measuring net. To detect and monitor underground fires through fire gases measurement and -analysis, a mobile underground testing laboratory collects data locally in the area of the fire. These laboratories have proven to be extremely useful not only during the actual fire fighting but also for the long-term gas measurements in critical mine areas. They have repeatedly detected starting fires and have thus given the mine the opportunity to react early and to avoid larger damage. Therefore several mobile laboratory units have now been installed for long-term testing in a number of German mines and similar units are being used in the Czech Republic and Poland.

Jan 1, 2012

By S. J. Schatzel

In order to better understand the effects of longwall mining on the methane reservoir overlying the panel, the National Institute for Occupational Safety and Health/Pittsburgh Research Laboratory (NIOSH/PRL) designed and implemented a vertical borehole monitoring experiment (BME) on an active longwall panel. The mine operates in the Pittsburgh Coalbed in Greene County, Pennsylvania. The BME site was located away from either end of the panel to avoid mechanical influences caused by the draping of overburden in this region and was positioned at the same distance from the tailgate gateroad as the mine?s gob gas venthole sites. The borehole drilling depths and monitoring intervals were chosen to address a different stratigraphic zone in each of the three planned holes. The monitoring boreholes were positioned perpendicular to face advance using a close spacing pattern of about 15 m (50 ft) between collars. Boreholes were instrumented downhole and on the surface for various measurements. It was observed from the field data that the gob gas venthole fracture network formed 24-46 m (80-150 ft) ahead of the mining face. Overburden permeability?s within the same test zones increased 100 to 500 times following undermining. The borehole test interval within the fractured rock responded to overburden gas pressure while the test interval in the caved zone responded to mine ventilation conditions. Eight months after the boreholes were undermined, slug testing indicated permeabilities had increased further in the fractured rock zone. Measurements of surface movement indicate that the permeability development observed in the boreholes is a product of vertical subsidence without lateral movement within the tensional rock mechanics zone on a supercritical longwall panel. Results from this study suggest that maximum permeability in the longwall panel overburden is achieved 58 to 190 m (190 to 620 ft) behind the longwall following maximum compaction of the overburden.

Jan 1, 2009

By G. S. Takenaka

When Bridger Coal Company transformed their operations from surface mining to an underground longwall operation their plans included not only the addition of new mining equipment but also surface fans for a blowing (supply) air ventilation system. The original system concept included a propane gas fired air heater to preheat the intake air during cold weather and a dual parallel fan and duct system. One fan operated to ventilate the mine while the other fan was for stand-by emergency operation. Equipment proposals were submitted in March, 2005 based on the dual parallel fan system. Discussions conducted during the equipment selection process revealed that several alternative system design concepts were available. The alternative concepts included innovation features that not only saved space and cost but also reduced operating expense as well. Many of the features were incorporated into the final design of the system. A comparison of the original system concept and final installation design are presented in the paper in addition to details of the features and the derived benefits.

Jan 1, 2009

By Y. P. Chugh

Additional field evaluations of a modified continuous miner using a new spray system and modified scrubbers have been conducted by the authors. In this demonstration, a comprehensive package for dust control on a continuous miner which included previously developed modifications to the scrubber, scrubber intakes and the innovative chassis spray system was demonstrated. Side-by-side comparisons of the modified miner and regular miner indicated that the miner operator with the modified miner was exposed to 62% less respirable dust. Ram car operators with the modified miner had 38% less respirable dust exposure and the return air on the modified miner had 19% less respirable dust. The mining conditions during side-by-side testing were very comparable. These results support the findings of the modified spray system studies conducted earlier at different mines in Illinois on four occasions and the modified scrubber system field evaluation studies.

Jan 1, 2009

By Helmut Hass, Michael B. Gilbert

The extension of the commuter railway system (S-Bahn) in Leipzig, Germany willrequire the construction of an underground line crossing the downtown area of thecity to tie the Bavarian Station in the South to the Main-Station in the North. The City-Tunnel-Leipzig is currently one of the largest infrastructure projects in Europe. This system extension will have a length of approximately five kilometers. 3.9 kilometers of that length are currently being constructed using either cut & cover construction or tunnelingmethods. The design and construction of this project currently is and will continue facing very significant challenging urban and demanding geotechnical conditions.

Jan 1, 2007

By J. Kretschmann

Around the world, mining has been done for thousands of years for the benefit of humankind. The winning process in mining operations ends with the depletion of the deposit or its closure if the operation becomes economically unprofitable. After that, a period of post-mining follows which may last for a very long time and which is generally regarded as a period of hazards, risk and high cost. In the USA alone, approximately 500,000 abandoned mines do exist; worldwide, there are millions. In Germany, too, we have had to deal with abandoned mines for a considerable period of time now.

Jan 1, 2012