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By Dermot Winters

The Surface Mining Control and Reclamation Act (SMCRA, or the Act) was enacted on August 3, 1977. The Act was written, in part, to put an end to uneven environmental standards and to establish minimum national standards. Certainly, one of the motivating factors for passage of the Act was the success of the Federal Coal Mining Health and Safety Act of 1969 in reducing deaths and injuries in the coal industry nationwide. Section 516 (b) (1) of the Act requires *that subsidence be prevented from causing material damage to the extent technologically and economically feasible except in those instances where the mining technology requires planned subsidence in a predictable and controlled manner. Section 516 (c) of the Act authorizes the regulatory authority to suspend underground mining if there is imminent danger to inhabitants of urbanized areas, cities, towns, and communities. On December 13, 1977, the interim program, which applies a portion of the performance standards of the Act, was promulgated. Then on September 18, 1978, the proposed permanent program was published for public comment. Finally, on March 13, 1979, the final permanent program was promulgated and the States were given a period of time to submit their programs for approval.

Jan 1, 1986

By John Sleavin

As part of the Link Light Rail project in Seattle, WA, work was completed at the Pine Street Stub Tunnel (PSST) in early 2007 for the Central Link project. This tunnel was excavated using cut-and-cover construction within the limits of Pine Street. The stub tunnel provides a turn back via double crossover for light rail trains running in the Downtown Transit Tunnel (DTT), as well as a connection point for the next phase of the project, the University Link (Fig. 1). Designing the new University Link tunnel connection to the existing PSST was a tricky task. The on-site geotechnical conditions, buried obstructions, geometry, requirements for construction and balancing operational considerations and neighborhood stakeholder concerns associated with the recently completed PSST combined to create a uniquely challenging assignment.

Jan 1, 2010

By Chris Tattersall, Tomyuki Kudo, Peter Raleigh, Nestor Garavelli, Steve Redmond, Michael J. Lehnen

Twin bore running tunnels driven approximately 4,500 route feet by a Mitsubishi Heavy Industries (MHI) EPB Tunnel Boring Machine link the West Portal and East Portal on this complex Light Rail Project. One third along the way, the TBM arrives at the Beacon Hill Station which is the deepest underground “binocular” station of its kind in North America and then “walks-across” the station to be re-launched on the other side to complete the drive. This paper discusses briefly the layout and design considerations but then focuses more deeply on the approach by the Contractor to drive and supply the tunnel. The paper addresses the approach used to launch, re-launch and recover the TBM and touches briefly on muck volume control and monitoring plus settlement monitoring and the performance achieved. Also of interest is a unique solution to a difficult launch situation involving a secant pile tieback wall designed with several rows of double I-beam steel walers spanning the eye at the West Portal under the I-5 freeway.

Jan 1, 2007

By C. D. Anderson

A variety of processing technologies exist for recovery from both primary and secondary sources of rhenium. Currently, there are no known primary rhenium deposits, thus, the method in which primary rhenium is produced is dependent on the commodity of which it is a byproduct, e.g., copper, molybdenum, uranium, etc. In addition, focus on the recovery of rhenium from secondary sources, such as alloy scraps and catalysts, is continually growing. This paper presents a review of both primary and secondary processing technologies for the recovery of rhenium. Key Words: Rhenium, Ammonium Perrhenate, Extractive Metallurgy

Feb 27, 2013

By R. Chen

Most tunnels built in Sydney encounter similar ground situations; they penetrate either the Hawkesbury Sandstone or the shales that lie beneath the city. Tunnels in these materials are generally sup-ported by rock bolts in combination with a shotcrete lining. A method of analysis is presented to improve our understanding of the long term behaviour of fiber reinforced shotcrete (FRS) materials and the tunnel support systems. A finite element method SAFEA (Semi-analytical FE Analysis) is developed to model the combined creep behaviour of a shotcrete lining and the Hawkesbury Sandstone. To model the time-dependent creep behaviour, the bulk modulus and shear modulus of the materials are represented by logarithmic functions in time. A Laplace transform is then applied to these functions of time and the solution of the problem found from a finite element analysis. Tablot?s method is then used to invert the transformed values and find the solution in real time. The time dependent creep deflection of the numerical tunnel models reflects the interaction of the shotcrete lining and rock which have different creep parameters.

Jan 1, 2008

By Klaus Rieker

Over the last 30 years Wayss & Freytag Ingenieurbau AG has gained a lot of experience in mechanized tunnelling on various major projects. During this period most important developments concerning the machine technology for EPB- and Slurry-Shields have taken place. Since the first application of a hydro shield for the Wilhelmsburg Collector project in Hamburg in the early seventies, several stages of development have led to the current state-of-the-art in mechanized tunnelling. The continuous improvement of TBM techniques allows the execution of high quality tunnelling, particularly with regard to maximum safety and efficiency. The practical experience of the construction companies is of essential importance in order to continue further development and improvement.

Jan 1, 2005

By Verya Nasri

This paper presents analysis of damages and rehabilitation design for three major French rail-way tunnels built in mid-19th century. The La Nerthe tunnel underwent ovalization deformation with excessive displacement at the springline, and pinching and bursting of the liner bricks at the crown due to tectonic residual stresses with very high lateral earth pressure. The Saint-Louis les Aygalades tunnel invert was subjected to undulatory deformation resulting in tracks misalignment, which was caused by non-homogeneity of mechanical and hydraulic properties of the ground. The Roches de Condrieu tunnel required widening to comply with the increase in dynamic envelope of trains due to their larger cross section and higher speed. The applied rehabilitation methods and constraints of work in these busy mainline railway tunnels have been discussed in detail.

Jan 1, 2008

By S. Dessureault, Z. Gavelan

As globalization continues, sustainability and social responsibility has become essential in foreign mining investment. However this global trend and the increasing acceptability toward the globalization process, viability and sustainability are not always achieved. Viability and sustainability of mineral projects is dependant on the social and political environment of the region where the mining venture is located and is based on the interaction between the mining entrepreneurs, national-local government representatives, communities, grass-roots groups and independent civil organizations. These are the organizations, which play the acting roles on the viability of mining projects and are the main source of socio-political risks for the project. Throughout the decision-making process to invest in a mineral project, socio-political risks are quantified using a set of measurable variables. Nevertheless, these risk measures should be dependent on specific industries. Two mineral projects, even in the same mining district, may have significantly different political risk profiles based on their own socio-political variables. This paper describes a methodology that takes into account local social and political variables in defining a project-specific’s political risk profile. This contrasts with more typical political risk measures that focus on the country’s overall risk profile. Mining operations must operate on a local scale necessitating the development measure that considers more local variables.

Jan 1, 2004

By C. L. Kosmoski

The mining industry faces many workplace hazards that are a threat to human health and safety. The Bureau of Labor Statistics has found that employees in coal mining are more likely to be killed or sustain an injury or illness than workers in private industry. These injuries are also likely to be more severe (Bureau of Labor Statistics, 2007). In recent years, coal mining injuries have attained national attention due to highly publicized disasters. Despite these threats to worker safety and health, the U.S. relies on the mining of coal to meet its need for electrical power, with42% of electricity in the U.S. generated through the burning of coal (U.S. Energy Information Administration, 2012b; United Mine Workers of America, n.d.). Furthermore, the production of coal continues to increase and reach record levels every year(National Mining Association, 2012; U.S. Energy Information Administration, 2012a). For this reason, the coal mining industry must continue to find ways to protect its workers while maintaining productivity. One potential approach to protecting workers while maintaining productivity is through improving the safety culture at coal mines. In order to achieve this culture, operators, employees, the inspectorate, etc. must share a fundamental commitment to safety as a value. This type of culture is known in other industries as a ?safety culture? and can be defined as the characteristics of the work environment, such as the norms, rules, and common understandings that influence facility personnel?s perceptions of the importance that the organization places on safety. Fundamental to improving safety culture within an organization is understanding the existing safety culture; improvements cannot be made without first elucidating areas that require improvement. This manuscript details the process undertaken by researchers at the National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) to assess the safety culture at five underground coal mines across the United States. The purpose of this manuscript is to introduce the mining industry to a multi-methodological approach to safety culture assessments. Further, it is the goal of this manuscript to highlight the value of including both quantitative and qualitative methods into safety culture assessments in order to obtain the most comprehensive view of an organization?s safety culture. Because this manuscript focuses solely on the methodology implemented, data and results obtained during the five safety culture assessments will not be presented in this manuscript, but will appear in a future publication.

Feb 27, 2013

Construction of the Boddington Mine 130 km (81 miles) southeast of Perth, is about 89 percent complete. When the $2.9-billion development is finished, it will be the largest gold mine in Australia, producing 31 t/a (1 million oz/year), according to project majority owner Newmont Mining. Newmont?s acting regional group executive for Asia Pacific, Philip Stephenson, told a gold conference in Australia that the project would be ?the biggest thing for Newmont this year.? The project has been in the works for more than 10 years, but because of a three-sided ownership and fluctuating gold prices, it struggled to get started. However, Newmont is set to become the full owner of the project and is moving ahead on the low-grade project. ?We are targeting annual production of 31 t/a (1 million oz/year) for each of Boddington?s first five years. When it is in full production, Boddington will be the largest gold mine in Australia,? Stephenson said. ?The mine?s costs applicable to sales will be around US$9.64/g (US$300/oz) and that puts Boddington into the bottom quartile of the global cost curve. ?Strategically for Newmont, Boddington coming on-line will improve Newmont?s overall global geopolitical risk profile as it delivers greater exposure to an AAA-rated country.? Boddington has a projected mine life of 20 plus years. It has current total reserves of 622 t (20 million oz) and rising. Stephenson said Boddington has the largest reserve base of all gold projects in production or those that are about to go into production in A-rated countries or better. And it will be an important asset for many years to come. Newmont will acquire the remaining 33 percent share held by AngloGold Ashanti in a deal that should be concluded in the next two months. Australian miner Newcrest Mining Ltd. had exited the joint venture several years ago. Newmont had come into the project through the take-over of then Australia?s leading gold miner Normandy Mining, while AngloGold Ashanti gained entry through

Jan 1, 2009

By A. M. Whiting

Competition for coal producers and their primary customers has constantly increased during recent years. The effects of the Clean Air Act Amendments of 1990 on the electric utility industry, coupled with the normal complexities of coal production, quality control, transportation and contracting techniques have spurred both buyers and sellers to increase their level of sophistication. This paper will review the basic aspects of the U.S. coal business and explore the commercial approaches which have proven to be most successful.

Jan 1, 1994

By P. Venkatraman

Laboratory and pilot-scale test data have shown that the innovative feed presentation of the CrossFlow separator provides improved metallurgy when compared to traditional hindered-bed or teeter-bed classifiers. This design feature prevents excess water from entering the separation chamber and disrupting the overall fluidization flow rate within the teeter zone. Recent side-by-side industrial-scale evaluations have verified that this technology can improve overall efficiency, reduce the cut point of separation, and increase throughput capacity. This paper describes the important features that make this novel separator ideally suited for size classification and density concentration. Test data from heavy mineral, phosphate, and industrial mineral applications are also discussed.

Jan 1, 2005

By V. K. Paruchuri, J. D. Miller, J. Nalaskowski

The phenomenon of surfactant adsorption at mineral surfaces is of significant importance in many particulate processes ranging from mineral flotation and enhanced oil recovery to pharmaceutics, paint technology and the casting of high quality ceramics. Stability of the dispersions is related not only to the amount of adsorbed surfactant but also to the structure of the adsorbed surfactant molecules at the interface. This structure greatly depends on the type of surfactant and the hydrophobicity or hydrophilicity of the surface. On hydrophobic surfaces surfactants adsorb regardless of surface charge by van der Waals/hydrophobic inter-actions with hydrocarbon chains accommodated at the surface. On the other hand, on hydrophilic surfaces the surfactants adsorb through electrostatic interactions with their polar moiety fixed at the surface. In the latter case, the electric charge of the surface and surfactant plays a crucial role in the surfactant adsorption process. The recently developed soft-contact Atomic Force Microscopy technique has revealed images of adsorbed surfactant structures at various interfaces. The adsorbed structures of a cationic surfactant (CTAB) and an anionic surfactant (SDS) are presented in this work for different concentrations at hydrophobic graphite and hydrophilic mica surfaces. Different types of micellar arrangements have been observed at these surfaces for surfactant concentrations around the critical micelle concentration. The structures are more ordered and well defined at the graphite surface than at the mica surface. These results have been correlated with the hydrophobicity of the surfaces as revealed by contact angle measurements.

Jan 1, 2001

By C. Meyer, J. J. Eidel

C. W. Hunt I wish to register strong disagreement with the choices of drilling sites chosen by the Continental Scientific Drilling Committee, while endorsing the stated objectives. Of special significance is the lack of any site involving the metals most needed today in the US, while 9 to 13 km of drilling are allocated to gold and silver districts and 11 to 17 km to base metal (mainly copper) districts. Why is nothing proposed for platinum group or chromite? Is this because the committee did not know of such a site? If so, I offer such a site in California (see Fig. 1). The mineralization shown in Table 1 occurs in a large peridotite body in western Tehama County, CA. Petrography has demonstrated unequivocal evidence of migrated PGE deposited in peridotite and chromite of hypabyssal nature. Active diapirism (due probably to serpentine buoyancy) above a reactivated mantle to surface conduit marks the position of the conduit. Young explosion breccia cemented loosely by volcanic glass and tuff demonstrates the significance of the conduit as the prime source of the various emissions. Deep drilling could result in major metals discoveries as well as shedding light on the grand questions of platinum group mineralization. What role water has played in this occurrence is not yet certain; but chlorine and asphaltite have been detected in and adjacent to native PGM, suggesting a major role for water. The explosion breccia suggests that this excellent site could overlie entrapped geothermal steam.

Jan 6, 1987

By Qinbo Cao, Qianshan Peng, Heng Zou, Xingcai Yu

In this work, a new flotation strategy was proposed for the flotation of rutile. In this strategy, rutile was activated by Pb(NO3)2 and then floated with amyl xanthate (AX) as a collector at pH 8. Pb(OH)+ was the dominant lead species in the solution at pH 8 and is believed to be the major species reacting with the rutile surface. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) study revealed that the lead activation products were well distributed on the rutile surface, and AX− could further bind with the Pb atom on the Pb-activated rutile surface. In this regard, the Pb-activated rutile could be floated by AX. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis indicated that Pb(OH)2 was generated on the Pb-activated rutile surface. The electron transfer during the adsorption of the AX− on the Pb-activated rutile surface was also investigated by XPS analysis.

By Qinbo Cao, Qianshan Peng, Heng Zou, Xingcai Yu

In this work, a new flotation strategy was proposed for the flotation of rutile. In this strategy, rutile was activated by Pb(NO3)2 and then floated with amyl xanthate (AX) as a collector at pH 8. Pb(OH)+ was the dominant lead species in the solution at pH 8 and is believed to be the major species reacting with the rutile surface. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) study revealed that the lead activation products were well distributed on the rutile surface, and AX− could further bind with the Pb atom on the Pb-activated rutile surface. In this regard, the Pb-activated rutile could be floated by AX. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis indicated that Pb(OH)2 was generated on the Pb-activated rutile surface. The electron transfer during the adsorption of the AX− on the Pb-activated rutile surface was also investigated by XPS analysis.

By A. Ayoubian, V. Nasri

This Tunnel Connection project will include construction of two short tunnels to connect the existing subway tunnels (Red and Blue lines) in the northern loop area of downtown Chicago through a new station. The Southeast Tunnel will connect the Red Line to the new station below the intersection of State and Washington Streets and the Northwest Tunnel will connect the Blue Line to the new station below the intersection of Dearborn and Randolph Streets. The connection tunnels are located in a very dense urban area of downtown Chicago and under several important historical buildings. Both tunnels are curved at the intersections and located at a depth of about 7.5 m below ground surface in saturated soft clay with an average undrained shear strength of approximately 25 kPa. The design calls for minimizing surface disruption and ground displacement while maintaining normal operation of the existing subways during the construction of the connections tunnels. This paper presents mining and cut and cover tunneling alternatives for the project.

Jan 1, 2007

In order to ensure safe mining and reduce surface damage in shallow multiple-seam mining, the failure characteristics of interburden strata with different coal pillar offset distances between pillars in the upper and lower seams, the distribution characteristics of stress concentration in coal pillars, and the development characteristics of stratum cracks and subsidence were physically investigated and also using UDEC2D software. Meanwhile, the effect of different coal pillar offset distances on the stress concentration of coal pillars and development of stratum cracks were studied. Based on those results, a formula for safe mining and reducing surface damage was established, which provided a theoretical basis for safe and environmentally friendly mining in shallow multi-seams. According to the results of the study, the optimal coal pillar offset distance (the side-to-side horizontal distance of the upper and lower coal pillars) between the upper and lower coal seams was developed to reduce the stress concentration of coal pillars and surface damage. The results of this study have been applied in Ningtiaota coal mine and have achieved good results in safe and environmentally friendly mining.

Jul 28, 2020

By Mark Rybak

On Aug. 31, 2006, Tropical Storm Ernesto hit the city of Richmond, VA. The Battery Park area was hit particularly hard, as flooding forced an evacuation of the area. A large sinkhole collapsed a sewer line in the Battery Park area, blocking the pipe and causing more serious flooding. This article describes the fast track design, bidding and construction of an emergency tunnel to bypass the collapsed sewer. Innovative value engineering, tunneling and shaft-sinking methods and final lining design all contributed to the success of this project. The storm inundated Richmond, VA with up to 305 mm (12 in.) of rain that, in some areas, caused widespread flooding and damage. One of the hardest hit areas of Richmond was Battery Park. A major trunk sewer in the Battery Park area collapsed and caused local combined sewer and stormwater flooding. The collapsed sewer was a 2.4-m x 76-mm (8-ft- x 3-in.-) wide by 2.7-m- x 152-mm- (9-ft- x 6 in.-) high arch sewer that was constructed in the 1920s and later filled over with municipal solid waste and a soil fill cap to cur-rent elevations. A sinkhole was created in the area of collapse approximately 18 m (60 ft ) deep and 31 m (100 ft) in diameter. This caused the existing arch sewer to become blocked. As a result of this blockage, contaminated floodwaters reached depths in low-lying areas in excess of 8 m (25 ft).

Jan 1, 2008

By Timothy P. Smirnoff

Sustaining the region?s mobility needs, achieving projected economic growth, and maintain Midtown Manhattan as a center of regional, national and global importance has led to continued investment in commuter rail and transit infrastructure in New York City and resulted in design and construction of large underground caverns. The current plans for stations in Manhattan include New York Penn Station Expansion (NYPSE) caverns for Trans Hudson Express (THE) Tunnel Project for New Jersey Transit (NJ Transit) and the Port Authority of New York and New Jersey (PANYNJ), Metropolitan Transportation Authority Capital Construction Long Island Railroad (MTACC/LIRR) twin caverns for East Side Access (ESA) Project, and station caverns of the No. 7 Line Subway Extension Project and Second Avenue Subway Project for Metropolitan Transportation Authority Capital Construction/New York City Transit (MTACC/NYCT). This paper provides a general overview of these large caverns now in design or construction in Manhattan, the area?s geologic setting, the geotechnical factors considered and approaches commonly applied for cavern design.