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By Raquel Costa, Aldino Campos, Frederico Carvalho Dias, Pedro Madureira, Patrícia Conceição, Ana Filipa Marques, Andreia Afonso, Maria Ana Martins, António Calado, Luísa Pinto Ribeiro

Since its formation in 2004, the Task Group for the Extension of the Continental Shelf (EMEPC) has been collecting hydrographic, geological and geophysical data to support the extension of the continental shelf beyond 200 NM. In 2008, the EMEPC acquired a 6,000 m rated ROV named "Luso" and has been cooperating with several national and international institutions to increase and improve its operational capabilities to conduct research on deep-sea minerals. The Portuguese continental shelf corresponds to a broad area of the seafloor encompassing different physiographic domains: the mid-Atlantic ridge system, abyssal plains and numerous seamounts. From 2008 to the present, the mid- Atlantic ridge and seamounts have been the most visited sites with the ROV "Luso". Several hydrothermal vent sites are known to occur along the mid-Atlantic ridge to the south of the Azores archipelago and mostly within the Portuguese EEZ. Vent fields were also discovered in the extended continental shelf, namely the Rainbow and the Moytirra sites located to south and to the north of the Azores archipelago, respectively. The most studied seamounts correspond to those forming the Great Meteor chain and the Madeira- Tore rise. All these visited sites are related either with the occurrence of polymetallic sulphides or cobalt rich Fe-Mn crusts and the opportunities to further pursue their exploration will be discussed.

Sep 1, 2014

By Donald W. Foss

The Shiloh Church deposit is a very significant molybdenum occurrence in an ususual, perhaps unique, geologic environment. Work done to date indicate that several million tons of "ore" may be present, occurring as a matrix in limestone and dolomite breccias. Mineralized rocks cored to date are at or near the surface and the deeper resource potential has not been tested. The prospect is located in Polk County, north- western Georgia (Fig. 1). The "ore zone" was outlined by North American Exploration, Inc. (NAE) using geochemical prospecting techniques. Extensive geological work, including core drilling, has been conducted on the properties, together with geochemical and geophysical surveys. The geology, geochemistry and geophysics of the prospect are discussed. It is hoped that these data can be used to formulate exploration programs in similar terranes located elsewhere in the eastern U.S.A.

Jan 1, 1983

By Steve Kral

The dramatic rescue of nine Pennsylvania coal miners trapped nearly 90 m (300 ft) underground for77 hours probably would not have happened without the high technology equipment and improved mine rescue training techniques available today. By now, most everyone has heard the story of the accident that occurred at the Quecreek Mine near Somerset, PA. At about 9 pm on Wednesday, July 24, the miners were drilling coal in the room-and-pillar mine. Their drilling accidentally punched through to the adjacent, abandoned Saxman Mine. Old mine maps of the Saxman Mine led Black Wolf Coal, Quecreek’s owners, to believe they were between 60 to 90 m (200 to 300 m) away from the abandoned mine. Those maps proved to be inaccurate.

Jan 1, 2002

By Ting Ren, Lihai Tan, Alex Remennikov, Xiaohan Yang, Xueqiu He

"Due to recent coal bursts in Australian coalmines, research of coal bursts has attracted intensive interest from mining researchers and engineers worldwide. Previous research has shown that the sudden drop of fractal dimension may be a precursor of catastrophic failure of rock. This paper examines the fractal characteristics of temporal-spatial distribution of acoustic emission signals released during the compression loading process of coal. This research suggests the possibility of coal burst forecasting based on acoustic emission data. The concept and calculation equation of fractal dimension is introduced in this paper. Additionally, uniaxial compression experiments of Australian coal samples are conducted, and the acoustic emission waveform and 3D location are recorded simultaneously by eight sensors Express-8 AE monitoring equipment in the loading process. The experimental results indicate that the continued slowdown of fractal dimension in time sequence can be used as a precursory signal of coal sample brittle failure. The fractal dimension of the spatial distribution of acoustic emission events decreases with the evolution of coal fracturing.INTRODUCTIONCoal bursts refer to the catastrophic failure of overstressed coal subject to the dynamic and static loads. In recent years, coal bursts have occurred in major coal mining countries and this phenomenon has attracted the research interests of international mining and geotechnical scholars. A total of five coal burst accidents happened in Australian coalmines since 2014. On October 20, 2018, a coal burst occurred at Longyun Coalmine in China’s Shandong province, which led to 21 fatalities. Unfortunately, even after decades of research, it seems neither more accurate forecasting methods nor comprehensive controlling measures put forward by researchers have solved the problems posed by coal bursts.As an instantons energy releasing process, coal bursts are always associated with energy dissipation in the forms of acoustic emission, micro seismicity, and electromagnetic radiation (Yamada, Masuda, and Mizutani, 1989). It is believed by many researchers that the frequency–magnitude relationship of micro seismicity induced by rock failure satisfies Gutenberg-Richer relationship as well (Feng et al., 2017). Hence, based on the principal and theory of earthquake source locating, micro-seismicity monitoring equipment has been adopted in many coalmines to locate seismic event origins associated with coal and rock failure in an attempt to better forecast coal and rock bursts. Although many parameters such as b value (parameter of Gutenberg and Richter’s law) (Lu et al., 2015) have been adopted as indicators of risk, the forecasting of coal bursts is still of low accuracy. The same is true with earthquake prediction, as it remains as a worldwide problem even after decades of research and practice. Acoustic emission (AE) methods are now widely adopted to detect rock failure processes under an applied stress for application predicting the abrupt failure of rock in the laboratory (Li et al., 2017). Previous studies have found that significant overlap exists between research regarding AE and micro seismicity with respect to generation process (both are concerned with the generation and propagation of elastic wave) and event origin location, as geophysical signals of both are same (Lockner, 1993). That is, the frequency–magnitude relationship and early-warning indicators found by AE research in the laboratory have a potential applicability to in-field micro seismic monitoring of coal bursts. Through experimental study, Feng and Seto found that the temporal distribution of acoustic emission counts of rock have distinct fractal structures during load-increase processes (Feng and Seto, 1999). Landis and Lucie found good correlation between fracture energy and AE energy during testing of mortar specimens as well (Landis and Lucie, 2002). Based on preliminary experimental study, many schol"

Jan 1, 2019

By Jean-Michel Rendu

That you are giving the Daniel C. Jackling award to me is a great personal honor. But more significantly, it is a recognition that geostatistics has come of age. And since I am considered by many as belonging to an older generation of geostatisticians, I thought that it would be fitting that I reflect on where geostatistics came from and where it might be going. First, though, let me propose a definition of geostatistics. Etymologically, paraphrasing Webster's definitions of "geo" and "statistics," it is "a branch of mathematics dealing with the collection, analysis, interpretation and presentation of masses of numerical data taken from the earth." This definition is most appropriate in the context of mining geostatistics. It includes both classical and spatial statistics. It emphasizes the earth aspect, or the analysis of geologic features. And it should remind the practitioner that geologic input is a critical part of all geostatistical applications. In the 1910s, statistical methods were already used to analyze geological data. However, the origin of geostatistics, as we know it today, is best set in the late 1940s, when H.S. Sichel recognized the lognormal distribution of sample values in the South African gold mines. In 1951, Daniel Krige observed that "it can be expected that the gold values in a whole mine will be subject to a larger relative variation than those in a portion of the mine." In other words, samples taken close to each other are more likely to have similar values than if taken farther apart. This observation is the foundation on which spatial statistics, which characterizes values defined in a multidimensional space, is built. However, the 1950s were marked by studies based on classical, as opposed to spatial, statistics. It was only in the 1960s that the need was recognized to model the similarity between sample values as a function of the distance between samples and that the semivariogram was defined. A theoretical framework was developed by Matheron that supplied an elegant mathematical explanation to the empirical observations made by Krige. Matheron coined the term "kriging" in recognition of Krige's pioneering work on the geostatistical evaluation of mineral deposits. As soon as this theoretical framework was developed, it was possible to bring geostatistics to the academic world. The "Centre de Geostatistiques" was founded in Fontainebleau. Numerous students were trained there, disciples eager not only to improve the theory and develop more sophisticated mathematical tools, but also to spread the new faith throughout the world. Expansion of geostatistics exploded in the 1970s, arguably the most fertile decade if it is judged by the frequency of theoretical breakthroughs, the number of original publica-

Jan 1, 1995

By Jon Y. Kaneshiro, Eric Dawson, Pooyan Asadollahi, Steven Hunt

This paper provides updates to the paper published by the lead author at RETC 2011 with a summary of developments in technologies, products, and approaches to corrosion analyses of gravity sewer tunnels and microtunnels. This paper presents approaches in evaluating degradation of reinforced concrete liners. Also, the carbon footprint of conventional concrete liners and alternative “green” liners are compared and their life cycle costs are considered. A few case histories from the past decade are provided indicating the latest and emerging trends in liner protection.

Jun 13, 2023

By R. Adsero

"A high altitude review of the state of the mining industry provided by a study of multifactor productivity shows a continuation of lower output year on year for the capital and labor inputs applied. The story is sadly similar for both U.S. mining and the Australian mining sector. In fact, according to PwC analysts, the world’s mining equipment productivity has declined 20 percent during the past seven years (Lumley, 2014). Although the reasons for the continuing decline in mining productivity are varied, the need for improvement is clear.The world’s mining industry fleet of more than 400 large draglines moves billions of tons of overburden and ore (phosphate, limestone, etc.) annually. This discussion will review a few of the tools available for improved productivity in dragline operations.Benchmarking equipment performance exposes the possibilitiesIn the September 2013 Mining Engineering cover story Graham Lumley and R. Adsero suggested that analyzing best practice equipment performance from an industrywide database for specific equipment performance improvement goals would be beneficial (Adsero, 2013). Benchmarking equipment performance by normalizing differences and then comparing specific measures of performance will provide a road map to improvement for those following the leaders. For those already performing at best practice levels, a benchmark confirms and bolsters what has already been achieved. As described in the SME February 2014 paper by this author, best practice is the average of the top 10 percent in annual output. Filling performance gaps identified by a comparison to best practice by investigating the details of the why and taking action to change, makes all the difference. This is true for all major mining equipment. Given the large gap between average performance and best practice performance most mining operations can benefit. Best practice performance provides a view of what is possible to the 90 percent majority of mining operations that are performing below the top 10 percent.For dragline mining operations, identifying specific characteristics and practices of leading dragline performance will provide a reference for comparison."

Nov 1, 2016

Despite limited discussion, Chemistry of Flotation is a good text and reference 1985 by M. C. Fuerstenau, J. D. Miller, and M. C. Kuhn Society of Mining Engineers Caller No. D Littleton, CO 80127 Softcover, $23.50 (member), $18.50 (student member), $28.50 (list) Review by Richard R. Klimpel Chemistry in Flotation, as stated by the authors, is intended as a textbook for students as well as a reference book for practicing flotation engineers. It covers subject matter related to surface phenomena; collectors and collector salts; natural floatability; the flotation of sulfide minerals, insoluble oxide and silicate minerals, semisoluble salts, and soluble salts; and slime coatings. There are no discussions in the book on practical plant implications of flotation chemistry, such as the influence of rate, particle size effects, dosage, flotation equipment, and methods of chemical addition. The book itself is small (only 177 pages), and, as published, is in an easy-to-handle soft cover. Once one accepts the intent of the authors, this book really does represent a very concise and convenient summary of the chemistry of flotation. It is, however, far from complete in its discussion of concepts and implications of data. Very often in the presentation, key prior knowledge (or at least subject matter awareness) not given in the book, is assumed. Thus, depending on one's familiarity with the specific subject matter, some sections can be easily followed while others could be tough going. Some of the discussion is so brief and terse on important subjects that unless the reader already realizes the meaning of the presentation, the conclusions to be drawn are not always clear. Therefore, if one is not expecting a self-contained primer on flotation chemistry, this book is very useful. To this end, the book is recommended to practitioners of flotation chemistry. The presentation of data in figures and tables is good. It helps considerably in the book achieving its conciseness. The authors certainly are qualified and knowledgeable in the subject matter - apparent in the style of presentation. In summary, this reviewer thoroughly enjoyed this book and will use it as a concise review of flotation chemistry. Richard R. Klimpel, member SME, is a scientist with Dow Chemical Co., Discovery Development, 1776 Building, M. E. Pruitt Research Center, Midland, MI 48640. International Symposium on Blast Furnace Ironmaking, 1985, The Indian Institute of Metals, The Tata Iron and Steel Co., Ltd., Jamshedpur 831007, India, 282 pp., papercover, no price given - Papers from this symposium held in Jamshedpur, India, include the following: determination of coal and coke quality; feed to blast furnaces; burden quality and blast furnace performance; operation of blast furnaces on charcoal; review of cast house slag granulation systems; developments in blast furnace engineering and control; process improvements in blast furnace ironmaking; coal injection into the blast furnace; and coke from stamp charged coal. Advances in Materials Technology for the Process Industries, 1985, edited by H.A. Huskins, National Association of Corrosion Engineers, P.O. Box 218340, Houston, TX 77218, 273 pp., softcover, $20-This book is the proceedings of a meeting held in Atlanta, GA in October 1984. It describes innovations in metallurgy, ceramics, glass, composites, and polymeric materials that impact the integrity and economics of operating systems. It covers biotechnical developments, improvements in membrane systems, or beneficiation processes, as well as developments in electrochemical controls, testing procedures, and surveillance techniques. A Reference Guide to Mining Legislation in Canada, 1985, by B. Barton, B. Roulston, and N. Strantz, The Canadian Institute of Resources Law, Room 430, Bio Sciences Building, The University of Calgary, Calgary, Alberta, Canada T2N 1N4, 120 pp., bound, $US28- This guide provides a ready means of finding how the different jurisdictions in Canada regulate mineral activity. It covers the rights required for exploration, development, and production of mineral metallics and industrial minerals. It does not cover placer mining, petroleum and natural gas, bituminuous sands, coal, or structural materials. Dictionary of Geological Terms, 1985, edited by Robert L. Bates and Julia A. Jackson, The American Geological Institute, 4220 King St., Alexandria, VA 22302, papercover, $7.95 plus $1 for postage - This third edition is for geoscience students, teachers, and rockhounds. It defines the core vocabulary of earth sciences, contains 8000 revised definitions, and includes 1000 new terms. It adds recent terms in plate tectonics, hydrology, and permafrost studies. Accurate definitions are given without technical jargon, cross-references are included, and commonly used abbreviations are provided. Processing and Utilization of High Sulfur Coals, 1985, edited by Yosry A. Attia, Elsevier Science Publishing Co. Inc., 52 Vanderbilt Ave., New York, NY 10017, 787 pp., bound, $142.50-These proceedings comprise the majority of the papers presented at the First International conference. Investigators there reported the latest discoveries, developments in commercial practice, and state-of-the-art reviews of scientific principles and applications of various technologies for handling, processing, and use of high sulfur coals. Sessions were held on: characterization of sulfur in coals; environmental problems and impact of high sulfur on coal use; selective mining and blending; coal desulfurization by physical and chemical cleaning techniques; handling of coal fines; sulfur capture during coal combustion; biological desulfurization of coal; and new applications for high sulfur coal. The Economics of Magnesium Metal, 1985, Roskill Information Services Ltd., 2 Clapham Road, London SW9 OJA England, 129 pp., 71 tables, appendices, bound, $750-Despite setbacks in some major magnesium markets in 1985, Roskill's latest forecast for the last half of this decade is for a 4% to 6% annual growth rate in demand. Growth for magnesium metal is expected in the motor industry for use as a possible substitute for aluminum. Some magnesium producers are altering their marketing strategies to cultivate this market. This study also includes a review of the worldwide magnesium industry, its end uses and consumption, and international trade and price trends.

Jan 7, 1986

By Sean Masse

New Gold?s New Afton Mine, located 8 km (5 miles) west of Kamloops, British Columbia, is a 4.5-Mt/a (5-million stpy) block cave mine, making it the highest tonnage underground hard rock mine in Canada. The reserve is estimated at 52.5 Mt (55.9 million st) with grades of 0.65 g/t (0.02 oz/st) gold and 0.93 percent copper (2012). Commercial production was achieved in July 2012 and nameplate production was achieved ahead of schedule in September 2012, with the cave breaching to surface in 2013. The mill has a SAG and a ball mill with a froth flotation circuit.

Jan 1, 2014

"Use of the Bond Work Index to size industrial grinding equipment was widely known. Bond also described its application for measuring grinding circuit efficiency. Bond Work Index efficiency has been widely used by industry, but until now without concise standard methods, or a formal guideline, for doing so. The Bond Efficiency Sub-Committee of the Industrial Comminution Efficiency work group of GMSG has produced such a guideline, which follows. It covers the methods and provides examples of how to calculate the Bond Work Index Efficiency of most industrial grinding circuits. Bond Work Index testing equipment and methods are also provided. The next steps are: (1) to establish standard reference testing materials and one or more laboratories to serve as bases for reference testing; (2) to establish the accuracy of relative circuit Work Index Efficiency determinations; and (3), to develop and provide a public data base of industrial comminution circuit Bond Work Index Efficiencies. OUTLINE Introduction and Background Part 1. Determining the Bond Efficiency of a Grinding Circuit Method Demonstration/Example Calculations Bond Work Index Testing Equipment and Procedures Accuracy of Comparative Circuit WI Efficiency Determinations (under development) List of Symbols Part 2. Data Base of Bond Grinding Circuit Efficiencies (under development) References Annexes: A1. The Bond Crushing WI Test Equipment and Procedure for Bond Efficiency Determinations (Revised March 26, 2015) B1. The Bond Rod Mill WI Test Equipment and Procedure (Revised March 26, 2015) C1. The Bond Ball Mill WI Test Equipment and Procedure (Revised March 26, 2015) Introduction and Background Please see the references and slide presentation “Bond Efficiency SLC (rev3)-print.pdf.” This efficiency determination applies to most brittle materials in their naturally occurring (un-scalped) size distributions being treated in size reduction circuits down to a product sizing of approximately eighty percent passing 70 µm (see below). Unusually shaped materials (e.g. mica) should be regarded with caution. Part 1. Determining the Bond Efficiency of a Grinding Circuit Method In the plant: • Define the circuit for which the WI efficiency is to be determined • Procure samples of the circuit feed and product • Obtain the power draw of the size reduction equipment at the drive pinion(s) • Obtain the circuit throughput rate (dry tonnage) In the laboratory:"

Jan 1, 2016

By Eduardo M. Sacris

The performance of the grinding circuit, from the initial stages of operation to the present, is discussed. The mill efficiency as measured by the Bond grindability data and the operating work index is presented. The objective has been to produce a sand cyclone overflow containing not more than 6% +65 mesh. However, this has never been attained even at low milling rates. On the other hand, significant improvements in throughput were achieved by instituting some equipment changes and process modifications within the grinding circuit. The latest approach to solving the coarse grind problem is also discussed.

Jan 1, 1983

By A. E. Ketler

Conventional Atmospheric Monitoring System (AMS) installations for monitoring CO, CH4, O2 and air-velocity throughout underground mines are usually relegated to a modest 3-5 mile extent and with data communication speeds confined to a ponderous 1-5K baud range. New US-MSHA and state regulations require fast reporting of unsafe conditions, and the old 20-30 minute updates are no longer acceptable. To communicate farther and faster has always been a problem, because data reliability degenerates with excessive distances and high speeds. Because of this, very large mines often resort to costly optical-fiber media, using expensive OF cables and repeaters to obtain the necessary coverage. This entails high initial cost, as well as high maintenance and downtime costs to repair or replace broken optical fibers. Rel-Tek has pioneered with its DX-Bus communication data highway, which uses inexpensive twisted-pair telemetry cables, which can now communicate well into the 20-mile extent of the largest mines -- normally a brick wall for low-tech AMS systems. This extended range, enables the use of twisted-pair cables and provides a low cost alternative to OF systems. This paper discusses the DX-Bus, and its latest accomplishment, the ?B-LINK,? a unique high-speed communication repeater that maintains the 19.2K-Baud data rate. On-going innovations to our workhorse Millennia-DX computer software have kept pace with this extra speed/distance phenomenon, resulting in a dually-optimized AMS package: both hardware and software. Cost savings are substantial, and at no sacrifice of reliability ? nearly always at 100%. Sensor updates are measured in seconds, not minutes and hours. Twisted pair copper cable is cheap to purchase and install and a breeze to maintain. Rel-Tek uses the B-LINK's wide branching capabilities to enable the AMS to extend 20-miles both far and wide. Actual experience in large US coal mines -- both longwall and continuous mining operations -- confirms the large mine performance. The ventilation and safety benefits to the mining industry are immeasurable.

Jan 1, 2009

By A. Halim, A. Martikainen, S. GYAMFI

This paper outlines a unique case of the development of strategies to reduce ventilation and heating costs in Konsuln iron ore mine in northern Sweden. The mine, located just south of Luossavaara-Kiirunavaara Aktiebolag’s Kiruna iron ore mine, was developed as a test mine from 2018-2020 for the Sustainable Underground Mining (SUM) project. Besides functioning as a test mine, Konsuln also contributes to ore production. The existing mine ventilation system was designed for the current production rate of 0.8 million tons per annum (Mtpa). There is a plan to increase this rate to between 1.8 and 2.0 Mtpa.

Sep 30, 2021

By Steve Kral

The domestic mining industry may be in the doldrums but there appears to be hope, at least from a regulatory standpoint. At least one US senator believes that the events of Sept. 11, 2001 made many citizens see the need for the country to become more self-reliant on its growing energy needs. Even before that tragic day, however, the Bush administration was making a strong push to open up more public land for energy and natural resource development.

Jan 1, 2002

By Joseph J. Feiler

Fires in underground coal mines are persistent problems anywhere in the world that coal is mined. Coal fires pose safety and health hazards in the form of mine subsidence, loss of energy reserves, destruction of property and surface improvements, and air pollution. In 1995, the US Bureau of Mines (US-BM), in cooperation with the Colorado Division of Minerals and Geology (CDMG),entered into a contract with Goodson & Associates Inc. (GAI) to design and field test the effectiveness of a new foamed grout technology called ThermoCell. GAI is a Lakewood, CO geotechnical and mining reclamation engineering firm. The company developed ThermoCell to control and extinguish underground coal fires. The viability of the special grout and the technology of application were established during a full-scale field demonstration at the abandoned IHI Coal Mine fire, near Rifle, CO. Following acquisition of additional funding by CDMG in 1999, Goodson returned to the site in April to continue the grouting to fully extinguish the IHI fire.

Jan 1, 2000

By W. R. Dengler, R. S. Brown

In 1974, Brunswick Mining and Smelting Corporation Limited started a 48 million dollar expansion programme at their property in Bathurst, New Brunswick. A portion of the expansion plans includes a 26 foot diameter 4,525 foot deep shaft, underground crusher and conveyor excavations and lower level access development. J. S. Redpath Limited was awarded the contract for the new shaft and associated rock work in May 1974. Brunswick Mining and Smelting Corporation Limited, a member of the Noranda Group, operate this 10,000 ton per day lead, zinc, copper plant with proven reserves in excess of 90 million tons. While most of the ore is provided by the underground operation at the Number 12 ore body, some tonnage is produced from the open pit at the Number 6 ore body. Long range plans indicate a phasing out of the open pit and an increase in production from the underground operation. Existing facilities at the underground mine could not provide additional tonnage, thus the requirement for a new shaft. (Figure 1) The new shaft will also provide access to ore below the 2,800 level which is currently the bottom level of the existing facility. The contract called for sinking a 26 foot inside diameter, nine compartment concrete shaft 4,525 feet deep (Figure 2). Station access and ramp development from existing workings would be required to the bottom of the new shaft. In addition, development work for new crushing and conveying facilities was needed simultaneous with the shaft sinking.

Jan 1, 1976

By J. B. Platt

Many utility fuel choices 1990-95 defied expectations, with utility decisions and coal market developments ever more closely linked. The Central Appalachian coal boom never occurred; clean-enough coal was developed in the hard-hit Midwest; Colorado-Utah coal surged; Pittsburgh seam production strengthened; utilities embraced Powder River Basin coal; and emission allowance prices collapsed. Competition drove productivity gains, but the future is not a simple repeat. Phase 2 brings fewer viable compliance options. Mega-railroad pricing has become a key risk factor -- will this be countermanded by merging utilities and power market competition? Revenue losses from vintage contracts are problematic. Uncertainty also plagues natural gas, in spite of unanimity across major forecasts, since recent experience has been so heavily influenced by the gas bubble.

Feb 24, 1997

By B. Seegmiller, W. A. Hustrulid, O. Stephansson

Introduction The concept of in-the-wall haulage was formally introduced to the mining community in the early 1970s. The basic concept is simple. Rather than the traditional in-the-pit haulage/access ramp, single or twin ramps driven in the pit wall are used with crosscut connections on the working levels. The in-the-wall pit haulage system could be considered as part of the opening of a new mine, a way of completing to final depth an existing pit, or part of the transition from open-pit to underground mining with the ramp remaining as part of the access. This paper is intended to acquaint the reader, particularly mine planning engineers, with some of the possibilities presented by the concept. Nordstrom (1983) said, "In many countries, mining engineers are either open-pit or underground specialists and, hence, often don't consider the possibilities for combining the best aspects of each into a hybrid mining system." This is believed to be true. There are few "hybrid mines" employing, for example, open-pit methods with underground haulage systems. One reason is the variance with the experience of the mining company and the engineers involved. However, with today's low metal prices, innovative and unconventional thinking may be just what a property requires to remain in production. All the possible situations where an in-the-wall ramp might be considered cannot be presented here. Rather, a few examples will be discussed for illustration purposes. Potential savings in stripping costs A major cost in open-pit mining is associated with the removal of overburden and waste rock. Although much of this stripping cannot be avoided, the volume (V) associated with the presence of an in-pit haul road can be quite large, V 100 (pit depth) a (road width) 2 x road grade (%) As an example, consider a vertical ore body 400 m (1312 ft) long, 60 m (197 ft) thick, extending to a depth of 160 m (525 ft). Cross sections are shown in Fig. 1. Other data are: ore tonnage = 11 Mt (12 million st), ore density = 2.9 t/m3 (0.09 st per cu ft), waste rock density = 2.7 t/m3 (0.08 st per cu ft), road width = 20 m (66 ft), road gradient = 10%, and level interval = 10 m (33 ft). The evaluation has been made assuming that the pit slope (0) is constant around the pit except on the side with the haul road. On this side, the slope is decreased to allow for the road. Slope angles of 30° to 60° have been selected to indicate the dependence of stripping volume (V) on slope angle. The stripping at the ends have been calculated assuming representation by cones. The volume associated with the haul road is 2.6 Mm3 (92.8 million cu ft). A comparison of the strip volumes involved is shown in Table 1. As can be seen, the percent savings in strip volume varies from about 4% to 17% and depends greatly on the slope angle. It is perhaps more interesting to examine the savings in stripping costs that could then be used to cover the cost of the access ramp and the crosscuts for stripping costs of $3/m3 ($0.08 per cu ft). The cost with the road volume is 2.6 million x 3 = $7.8 million.

Jan 1, 1988

By Wern-ping Chen, Jean Habimana, Jinyuan Liu, Mirza M. Rabbaig, Robert Barbour

To mitigate and control the combined sewer overflows from 17 outfalls in the City of Detroit, three outfalls in Dearborn Heights and eight outfalls in Redford Township, the Detroit Water and Sewerage Department has completed the preliminary design of a storage tunnel in 2005. In 2006, a final design has revised the alignments and the inside diameter (ID) of the tunnel. The revised tunnel system includes an 11.28-km(7-miles) 9.14-m (30-ft) ID tunnel, a 24.4-m (80-ft) ID pump station, two work shafts about 15.2-m (50-ft) ID each, and 14 drop shafts with various IDs. This paper discusses the latest development of this tunnel system.

Jan 1, 2007

By Wern-Ping Nick Chen

Durability risks for underground facilities can be underestimated during design phase as compared to well-known geological risks. However, unclear durability requirements can result in construction schedule delay and change orders. Unlike bridges or buildings, a unified underground durability code or standard does not exist. This paper will provide a durability approach for underground facilities, including degradation modes, mitigations, and compliance measures during construction. In addition, this paper will address how to clearly specify durability requirements in a contract document to reduce disputes during construction and discuss key durability tests that are time consuming and will impact construction schedule if not timely planned.

Jun 23, 2024