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By G. R. Dasari

New Austrian Tunnelling Method (NATM) has been analysed by Finite Element method in two and three dimensions by Strain Dependant Modified Cam Clay (SDMCC) Model. The effects of construction sequence, stiffness of shotcrete and time dependency of shotcrete on surface settlement magnitude due to the NATM have been studied. Settlements obtained in 2D analysis, as expected, found to be more than the observations. The surface settlements obtained in 3D analysis found to be about 3 times less than equivalent plane strain analysis. This is due to mobilisation of soil strength around the tunnel face and soil-tunnel lining interaction. About 40% settlements occurred due to excavation of face at the monitor section and 60% after the excavation crossed monitor the section.

Jan 1, 1996

By J. S. Stachulak, K. A. Mackinnon

This paper deals with specifying and evaluating fans for mine ventilation projects. Topics such as fan and equipment design life, operating points, and operating conditions are discussed. Common operating problems, such as vibration, parallel operation, mechanical failure, erosion, corrosion, and deficient fan performance are covered. Apart from identifying the potential operating problems, likely causes and suggested remedies are given. Fan type, fan accessories, and likely system effects and fan testing are discussed. Suggestions on what should be covered when evaluating different fan options and proposals and suggestions on the verification of supplier claims and guarantees, including cost of operation, the evaluation of initial capital cost, estimate on maintenance costs, and likely replacement expenditure over the life of the fans. In addition, fan reliability, operational flexibility, suggested construction details and fan vendor past history and experience are reviewed.

Jan 1, 2004

By Ghassan Skybey

Australian coal mines uses state of the art technology in coal rib reinforcement. This paper highlights the development over the past 15 years in coal rib support technology, along with the advantages and disadvantages of each system. It also outlines the current trend in using coal rib reinforcement in speeding up the dowels installation to improve the current low drivage rate. An innovative cuttable dowel is discussed which improves the drivage rate. This new dowel is self anchoring it uses no resin anchor it has a 5 tonnes (5.51 tons) anchor capacity and can be fully installed in approximately 10 seconds.

Jan 1, 1995

By J. R. Goode

ABSTRACT Aurora Energy Ltd. is considering a 10,000 t/d process plant to produce 97 million lb (43,998,460 kg) of U3O8 over a 17-year project from uranium deposits in coastal Labrador. This paper summarizes the test work, mostly done by SGS Mineral Services in Lakefield, Ontario, and the economic studies supporting flowsheet selection. The proposed flowsheet includes semi-autogenous grinding (SAG) and ball milling, acid leaching using air/SO2 as an oxidant, and resin-in-pulp (RIP) extraction of uranium from the leached slurry. Other unit operations examined include ore sorting, heap leaching, liquid- solid separation, solvent extraction, and nanofiltration for eluate upgrading. We also review the extensive environmental test work and studies that were completed.

Jan 1, 2012

By John E. Feddock

Retreat mining plays an important role in the coal production within Kentucky and the Appalachian Coal Basin. In Kentucky, the majority of retreat mining is performed in the Eastern coal field. However, since September 2004, Kentucky has suffered four mining fatalities during retreat mining operations, and the coal industry has focused attention on the safety concerns associated with retreat mining practices. The Kentucky Department of Natural Resources (KYDNR) engaged Marshall Miller & Associates, Inc. (MM&A) to conduct a study to ensure that retreat mining is utilizing the best technology currently available and that the current available employee training programs afford maximum safety to miners. MM&A studied 34 coal mines that were conducting active retreat mining operations and represent about one third of all the mines with approved retreat mining plans in Kentucky. This paper summarizes the major research work conducted (Feddock and Ma, 2006) and recommends the practical methods for improving safety during retreat mining operations.

Jan 1, 2006

By Elaine T. Cullen

Underground mining, like many high-risk industries, is facing a crisis in the near future. This industry has traditionally relied on a master-apprentice relationship to train new workers, but experienced miners are retiring in large numbers, leaving few "masters" to properly train their replacements. With a recent resurgence in mining, many new miners are entering the workforce each day. The rise in the number of inexperienced workers has implications for worker safety in an industry in which one mistake can blow up the entire workplace. The explosion in the Darby Mine in May 2006 that killed five miners illustrates what can happen in hazardous environments such as underground mines. The Health Communications Team at the National Institute for Occupational Safety and Health Spokane Research Laboratory was asked to address this problem by developing new training and safety awareness materials to promote safe flame cutting and welding practices. This article describes how occupational ethnographic techniques provided insights needed for "new product development." The result of this work was a national initiative to raise awareness and to protect underground coal miners from the dangers of flame cutting and welding in an environment filled with solid fuel and methane (natural gas). Although this project was initially designed for the mining industry, the approach and lessons learned are applicable to any high-risk industry and should be of interest to other social marketing or occupational safety and health professionals.

Jan 1, 2009

By Gordon M. Miner

When I was originally invited to speak to this audience on the subject of the future supply of precious metals I was somewhat apprehensive and suggested that the Program Chairman select someone with more credentials. He declined and the results of our conversation gave me cause to reflect and recall the opportunities I have had over the years and how fortunate I have been to be associated with so many successful companies and knowledgeable people affiliated with the precious metals field. I discovered that since 1935, 1 have worked in or visited most of the gold and silver camps in the United States; have been a leaser of a gold mine in Mohave, California; have both lost and made money in the silver futures market; have worked for two of the greatest precious metals companies in the United States - Homestake Mining Company and Hecla Mining Company, have spent a considerable amount of time in precious metal related discussions with men like Don MacLaughlin, Paul Henshaw, Dick Stoehr, Abe Shoemaker, Bill Love, Phil Lindstrom, Simon Strauss, Herbert and Bunker Hunt and many others. It is those exposures and experiences that I draw onto discuss the subject at hand.

Jan 1, 1980

By L. J. Gardner

Ore pass systems play a critical role in moving broken rock from the workplace to surface, and the integrity of the ore pass excavations is crucial. Over the life of the mine, ore pass integrity deteriorates, which may eventually result in the ore pass no longer being fit for purpose. This paper presents several case studies of successful ore pass rehabilitation exercises.

Jan 1, 2006

By A. Thatcher, C. Day, C. Meyer

The purpose of this paper is to provide general information about the bioaccessibility of metals and specific information about the use of bioaccessibility in risk assessments (human health risk assessments [HHRA] or ecological risk assessments [ERA]) and a list of sites where regulatory agencies have approved the use of bioaccessibility data in risk assessment. The memorandum also cites current U.S. Environmental Protection Agency (USEPA) guidance as well as state specific guidance where applicable. BRIEF HISTORY OF METAL BIOACCESSIBILITY TESTING AND METHODS The bioaccessible fraction of a constituent is that fraction that dissolves or desorbs from its matrix (e.g., soil) in the gastrointestinal tract and is available for absorption (USEPA 2007a; ITRC 2011; ITRC 2017). This is different from the bioavailable fraction, which is the percentage of the amount of an element that an organism is exposed to that is absorbed by that organism during a given time under defined conditions (USEPA 2007a). The bioaccessibility factor is the percentage of a metal that is potentially available for absorption and, therefore, is a conservative estimate of the bioavailable fraction since all that is available for absorption may not ultimately be absorbed into the organism’s system. Currently, there are two main techniques for estimating bioavailability of metals within a medium: in vivo animal studies (time-consuming and often cost-prohibitive), and in vitro tests that simulate human, or animal digestion in a laboratory setting. In vitro and in vivo test methods and protocols have been extensively evaluated by numerous researchers (Ruby et al. 1996; Rodriguez and Basta 1999; Sips et al. 1998; Sips et al. 2001; Molly et al 1993; Oomen et al 2002; Kelley et al. 2002; Oomen et al. 2003; Furman et al. 2006; Drexler and Brattin 2007; Basta et al. 2007; Wragg et al. 2009; Wragg et al. 2011; Chaney et al. 2011; Bradham et al. 2015; Bradham et al. 2018). The most recent scientific literature demonstrates that protocols used to estimate the bioavailability of metals to mammals also predict bioavailability of metals to birds as well (Beyer et al., 2016).

Jan 1, 2019

By David C. Oyler, Hakan Gurgenli, Gregory M. Molinda

Historically, miners have known that roof rocks originally composed largely of mud were prone to slaking and deterioration when exposed to water and humidity. Mine Safety and Health Administration (MSHA) records show that roof falls are more prevalent in summer and late fall. Field data shows higher bolt loads and increased room convergence in summer months. Laboratory data shows that very high internal pressures can be generated by significant strain in clay-rich rocks. In summer months humidities ranging from 70-100% can cause rock strains up to 7%, and rock pressures of 14,000 psi, more than enough to break apart weak shales and fireclays. The National Institute for Occupational Safety and Health (NIOSH) conducted wet/dry immersion cycling of clay-rich rocks. Results show that the rocks most prone to moisture deterioration are fireclays, claystones, and sandy shales, all of which have disrupted bedding. Of the 7 mudrocks with a weatherability index above 40%, none showed consistent fissile bedding. Black shales were surprisingly resistant to wet/dry water immersion cycling. Generally, mixed rocks (stackrock), typically susceptible to horizontal stress, are more resistant to moisture-deterioration. Mine roof rocks tested with moisture sensitivity ratings above 50% (moisture sensitivity index ranges from 0-100 with 100 being the most sensitive) all came from mines which had roof skin problems and used supplemental support to prevent rock fall injuries. Some roof rocks showed lateral variability of moisture sensitivity values, suggesting the need for more samples in highly varying roof rocks. Swelling strains of mudrocks showed that almost all of the swelling occurred in the first 24 hours after immersion. The wet/dry immersion cycling test used provides an accurate, quick and inexpensive method for estimating the moisture sensitivity of mudrocks. With this information mine operators can begin to anticipate hazardous ground and prepare appropriate roof support.

This publication contains eight papers presented at a Bureau of Mines Technology Transfer Symposium in Charleston, W, on June 22, 1983, Five of the papers describe the results of Bureau-sponsored research on cabs and canopies for low-coal underground mining equipment. The other papers describe the efforts of three underground coal mining equipment manufacturers (FMC, Joy, and Lee-Norse) in the area of cab and canopy design.

Jan 1, 1985

By P. A. Rossouw, G. A. Fourie

Several attempts have been made over the latter half of the twentieth century to devise a system for the classification of underground mining methods. None of these are found to be totally successful. A revised classification is suggested with three main categories being identified by reference to fill requirements, steep stopes and stratified geological environments. Methods always needing lasting mass or structure fill include methods with timber-structured stopes and those with mass-filled (or cut-and-fill) stopes. Methods associated with steep stopes are subdivided into steep-stope-specific caving and steep-stope-specific non-caving (or self-supporting) methods. Methods not in the first two categories, often used in stratified geological situations, are not necessarily restricted to stratified environments and include caving as well as non-caving varieties. This category is further divided into room-and-pillar mining, longwall and shortwall coal mining and the type of open stoping found in gold or platinum reefs comprising overhand, underhand and breast-stoping variations

Dec 1, 1996

By Petrus Christiaan Pistorius, Makunga Daudet Seke

The flotation response of a Pb-Zn sulphide ore from the Rosh Pinah Mine (Namibia) was studied in the presence of inorganic depressants such as sodium cyanide and zinc sulphate. Poor flotation selective was observed in the rougher concentrate of the galena circuit despite the use of excessive amount of sodium cyanide. Batch flotation tests have shown that the use of cyanide alone is not efficient for the depression of sphalerite from the Rosh Pinah ore when milling is carried out according to the current plant particle size distribution. The use of both cyanide and zinc sulphate improved the selectivity between galena and sphalerite much better than cyanide alone. Flotation selectivity is limited by the mineralogical texture of the Rosh Pinah ore sample. Microscopic analysis has shown that the presence of sphalerite in the galena concentrate is also due to poor liberation between galena and sphalerite, especially in the middlings. Hence selectivity could be improved by regrinding the rougher concentrate prior to the cleaning stage. Keywords- Sulphide ores, Flotation, Flotation depressant, Mineralogy.

Jan 1, 2005

By Igor Zh. Bunin

A model for developing electric discharges between sulfide mineral (pyrite) particles under high-voltage nanosecond pulses in a liquid medium (water) is considered. A possibility of electrical breakdowns of liquid gaps between particles under nanosecond pulses is shown. This probability and the energy released in discharge channels depend strongly on the sulfide conductivity.

Jan 1, 2010

By G. Hoffman

Sustainable development has brought social, environmental and energy efficiency concerns together with management and governance of natural resources. Cement manufacturing, an energy- and natural resource-intensive industry, is adapting to meet sustainable development goals. Emission standards for cement plants and increasing energy costs have lead to changes in the use of natural resources and recycled materials. Utilizing pozzolans or supplementary cementitious materials (SCMs) as mineral admixtures in blended cement or as a substitute for cement in concrete lowers energy costs and CO2 emissions. Although the western U.S. is rich in natural pozzolans, artificial products, particularly fly ash, have greater use as mineral admixtures. Pozzolans and SCMs have many beneficial properties, such as preventing alkali-silica reactivity, a common problem in the western U.S. Barriers exist for mineral admixtures in the cement and concrete industries because of past inconsistencies in quality or availability. New environmental regulations on the primary industries producing artificial mineral admixtures could adversely affect the quality and quantity of these materials in the future.

Jan 1, 2009

Certain information contained herein regarding Champion Minerals Inc., including management?s assessment of future plans and operations, may constitute forward-looking statements under applicable securities law and necessarily involve risks, including but not limited to risks associated with mining exploration, operating costs, production costs, volatility of share prices, currency fluctuations, imprecision of resource and reserve estimates, environmental risks and ability to access sufficient capital from internal and external sources. As a consequence, actual results may differ materially from those anticipated in any forward looking statements. Plans, intentions or expectations disclosed in any forward-looking statements or information should not be read as guarantees of future results or events, and will not necessarily be accurate indications of whether or when or by which such results or events will be achieved. Except as required by law, Champion Minerals Inc., expressly disclaims any intention and undertakes no obligation to update any forward looking statements or information as conditions change. The historical mineral resources mentioned are strictly historical in nature and are non-compliant to National Instrument 43-101 mineral resources and mineral reserves standards, and should therefore not be relied upon. A qualified person has not done sufficient work to upgrade or classify the historical mineral resources as current National Instrument NI-43-101 compliant.

May 1, 2011

By George Markon

The importance of United States coal exports as a component of the national economy, the potential for growth of these exports, and the inter-national character of this sector of the coal industry are described in this report. The report summarizes some of the many background elements in the rise of United States coals to preeminence in highly competitive world markets. It presents some insight into this important sector of United States industry and the positive contribution of this sector to the Nation's balance of payments. It contains pertinent basic statistics on production, trade, and consumption of coal in most major markets for 1960-66. The report examines the movement of United States coals from mines to export markets, tracing and describing origins, exit ports, prices, and trends as well as inland and ocean freight rates and other data vital to an under-standing of some of the practices and complexities of the United States coal markets abroad. A brief sketch of coal production and consumption in principal importing countries is also presented with a short review of some of the more current practices and problems of these countries. Coal produced in inland areas of the. United States can be moved to and distributed economically within coal-producing countries overseas and in Canada. Quality coals from the United States can successfully compete with foreign coals in nearly any area of the world on a truly economic basis because of their high grade and their low cost which derives from the high productivity of the miner and from reasonable ocean freight rates. Because of tariffs, trade embargoes, quotas, and other restrictions, how-I ever, foreign coal markets are relatively limited. Further limitations are imposed in some countries by economic conditions which restrict all imports as a matter of financial and economic necessity. Despite these obstacles, United States coals have brought lower cost quality coals to a large segment of the foreign energy market.

Jan 1, 1968

Thermal method of diagnostic as a nondestructive monitoring is based on data logging of infrared radiation from heated surface or from the associated thermal field. Monitoring of gearcases and motors hidden faults, such as, bearing degradation (deep-seated wears and tears, fretting wear, spalling and jamming solids of revolution) is closely related to high variations in temperature. The use of portable thermal imaging devices provides considerable advantages due to: easy remote access to the unit under test even when it is operating; minimum time required to obtain information and an opportunity for a real-time diagnosis of the tested subject's condition.

Dec 6, 2010

By Z. Mullard

The introduction of social media platforms has ushered in a new era of interaction and information exchange, which impact business-to-society relationships. Mining companies are closely watching these platforms, as the industry takes a cautious approach to control flows of information. This paper explores the risks, challenges and opportunities of using social media, based on a qualitative mixed methods investigation with stakeholders from the Canadian mining industry. Generational and language barriers, misunderstanding and limited motivation from regulators make implementing social media platforms challenging and risky at an organizational level. The benefits of social media include being able to mobilize communities and share information in real time. Despite the challenges, the study found that 62% of mining stakeholders are incorporating social media tools, mostly in an ad hoc manner. Flexible strategies for transparent communication and public engagement are creating new opportunities for information exchange.

Jan 1, 2011

By Morgan L. Race, Matthew R. Glisson

"Most driven pile projects have plumbness limits from 0.25 in/ft (21 mm/m) to 0.5 in/ft (42 mm/m) to control bending stresses. For two projects, the project teams performed static load testing to evaluate performance of piles with sweep. One project, located in Grand Forks, North Dakota, used 9.625-inch (244-mm) diameter piles with a wall thickness of 0.395 inch (10 mm) and lengths ranging from about 130 to 160 feet (40 to 49 m). Measured pile sweep (lateral offset distance of the pile toe from the pile top) was between 12 and 17 inches (305 to 432 mm). Static load testing indicated that the piles could support the design load with axial deflection of less than 1 inch (25 mm) but only provided about 80 to 90 percent of the ultimate resistance at axial deflections of about 1.9 to 1.7 inches (49 to 43 mm), respectively. The other project, located in Shakopee, Minnesota, used 9.625-inch (244-mm) diameter pile but with a wall thickness of 0.352 inch (9 mm) and lengths around 50 to 90 feet (15 to 27 m). The measured sweep varied between about 20 and 63 inches (508 and 1,600 mm) for 9 of 214 piles driven at the site. Load testing indicated that these piles could provide the required design resistance with less than 0.3 inch (8 mm) of axial deflection and support the required ultimate resistance with about 0.5 to 0.6 inch (13 to 15 mm) to of axial deflection.INTRODUCTIONAnyone who has observed a significant number of piles has seen that, inevitably, the pile is not perfectly straight after driving. In spite of the best efforts of contractors, there are a whole host of reasons for piles to end up out-of-plumb or to have a curve, sometimes referred to as pile sweep. Most project specifications set limits for plumbness typically between 0.25 in/ft (21mm/m) and 0.5 in/ft (42mm/m) (USACE, 1991; PDCA, 2007; MnDOT, 2016; MoDOT, 2016). Closed-end pipe piles, including monotube or tapertube, are the only pile type that allow actual measurement of the final alignment of the pile.As Nadeem, et al. (2015) note, buckling failure of long, slender piles is the predominant mode of pile failure in soft soils. Pile sweep is just one source of buckling failure in long, slender piles. The nonlinear buckling analysis showed that increasing slenderness ratio and/or increasing degree of curvature decreases the loadcarrying capacity of a driven pile. Nadeem, et al. (2015) considered solid, steel pile with lengths from 24 to 66 feet (7.5 to 20 m), diameters from 9.75 to 26 inches (244 to 660 mm), initial bends from 2 to 6 inches (50 to 150 mm), and half- and quarter-sine shapes."

Jan 1, 2017