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In September 2003, a test was conducted to see if a115-mm- (4.5-in.-) diam Mocap Vari-Stem blasthole plug could improve the pattern of explosives using different top stemming material. The test took place at the J.S. Faulkroad and Sonsstone quarry in McCalisterville, PA. The test consisted of a production stone blast. Half of the holes were stemmed with standard crushed stone. Two-thirds of the remaining half were stemmed with Vari-Stem plugs and crushed stone. And the remaining one-third of the second 50 percent was stemmed with Vari-Stem plugs and only drill cuttings.

Jan 1, 2004

By J. Drelich

The highly-efficient and economically-feasible technology for bitumen recovery from US oil sands using a water extraction approach was developed at the end of the last century. This water-based bitumen extraction process has been optimized based on observations and analysis of microscopic mechanisms of bitumen release from oil sands and the bitumen transfer to a froth product as well as measurements of interfacial properties of bitumen. The wetting mechanisms that occur in the diluent-assisted water-based processing of US oil sands include bitumen film rupture and recession on sand grains and bitumen transfer to nucleated and injected gas bubbles. These mechanisms are reviewed in this contribution.

Jan 1, 2007

By D. R. Wilburn

This summary of international mineral exploration activities for the year 2005 draws upon available information from literature, industry and U.S. Geological Survey (USGS) specialists. It provides data on exploration budgets by global region and mineral commodity and identifies significant mineral discoveries and exploration target areas. It also discusses government programs affecting the mineral exploration industry and presents analysis of the mineral industry based on these data. Two types of information are reported and analyzed in this annual review of international exploration for the year 2005. They include budgetary statistics provided by Metals Economics Group (MEG) and information on regional and site-specific exploration activities in 2005 compiled by the USGS.

Jan 1, 2006

By Brendan Reilly, Jon Isaacson, Paul McDermott

Kenny/Shea JV is constructing the water intake tunnel for the new Elm Road Generating Station, a supercritical coal-fired power plant in Oak Creek, Wisconsin, being built by Bechtel Power Corporation. The intake tunnel system consists of a temporary mining shaft, pump house and intake channel riser shafts, and four lakebed intake shafts. An 8.33 m diameter, 2,800 m long TBM mined rock tunnel is being constructed to connect the shafts. The intakes are located 2.4 kilometers offshore in Lake Michigan. The shafts and tunnel are being constructed in glacial tills and Silurian Dolomite. The estimated tunnel completion is December 2007.

Jan 1, 2007

By Ray Hutton, Darrell Liebno, Taro Nonaka

Background Population growth and increasingly stringent regulatory controls on water quality across North America have resulted in municipal governments investing heavily in infrastructure to control what are known as Combined Sewer Overflows (CSOs).These are events which occur when combined sewers exceed their conveyance capacity during periods of heavy rainfall or snowmelt. The city of Atlanta, Georgia is one such municipality; with a population of over450,000 within city limits and a sewer system servicing 1.2 million including adjacent jurisdictions, the City of Atlanta has a Combined Sewer System (CSS) encompassing approximately 15% of its total 3,540 km (2,200 miles) of sewers. Atlanta’s CSO discharges to local watercourses began to draw fire from environmental groups in the1980s. As a result, in the early 1990s, the City constructed a series of CSO control facilities which provided screening and chlorination at seven CSO discharge points across the CSS watershed. Unfortunately, these facilities were not capable of handling all of the overflows generated due to heavy storm events; frequently, untreated water was bypassed around the treatment facilities. The federal Environmental Protection Agency (EPA) deemed that water quality standards were being violated by these discharges, and a suit was brought against the City to force a higher standard of compliance. As a result, the City entered into a federal Consent Decree which would bring CSOs into compliance with federal standards by 2007. A critical component of this plan was the design and construction of the West Area CSO Tunnels and Pumping Station. In February 2003 the City’s Department of Watershed Management retained the services of Jordan Jones & Goulding/Hatch Mott MacDonald/Delon Hampton Associates (JDH Joint Venture) to design and provide construction management ser-vices for the project, which was designed to capture combined sewage from three of the City’s existing CSO facilities on the northern end of the CSS watershed. The design consisted of two connected tunnels which would convey the wastewater originating from the North Avenue, Clear Creek, and Tanyard Creek CSO facilities to a submersible wet well pumping station located at the R.M. Clayton Water Reclamation Center (WRC). Since the majority of the effluent stream consisted of storm water, the City elected to design and construct a separate treatment plant. This plant was designed under a separate contract, and is currently under construction.

Jan 1, 2007

By Thomas Kuhn, Carsten Ruehlemann, Christina Heller, Anna Wegorzewski

The commercial extraction of metals from manganese nodules on an industrial scale requires more than 50% of the investment necessary to realize manganese nodule mining. This is mainly due to the fact that a completely new metallurgical processing scheme for the extraction of both base metals (Ni, Cu, Co) and high-tech metals (Mo, Li, Ga) has to be developed and upgraded to industrial scale. There are a number of conventional processing technologies that combine hydro- and pyro-metallurgical approaches such as the INCO and CUPRION processes which have been developed in the 1970s and 1980s. Today, new approaches based on selective leaching with chelating agents and bioleaching try to minimize energy consumption and waste production. All of these extraction methods require knowledge how the metals are structurally bound in the manganese oxides. In this contribution we will review the current knowledge about the mineralogy of iron and manganese minerals in the different marine oxide deposits, present our results, and discuss the possible consequences for metal extraction.

Sep 1, 2014

S.L. Barua and Y.C. Kim M. Armstrong's paper is very interesting and can be regarded as a pioneering work of applying geostatistics on washed coal. The density levels used in her study are uniformly spaced, which facilitated curve fitting through a proper experimental design. Most of the existing coal washing plants in the US, however, gather washability data at non-uniform intervals which, in turn, affects the goodness of curve fitting. We would like to emphasize the importance of having a proper experimental design, if a similar geostatistical application is to be conducted on washed coal. We, at the University of Arizona, tried the variogram on recovery (Kim, Barua, and Baafi, 1982, SME preprint 82-143) which showed a similar pattern as Fig. 4 of Armstrong's paper. In both cases, the first experimental variogram value is invariably and inexplicably higher than the second variogram value. Although Armstrong ignores the first point because of "small number of sample points," we did not do so because there were 17 sample pairs. As a consequence, we concluded that the obtained experimental variogram was unsatisfactory and that further research is warranted. In other words, this disagreement in variogram interpretation between M. Armstrong and the University of Arizona begs the question whether the experimental variogram of Fig. 4 truly reflects the spatial correlation in washed coal, assuming there is such a correlation. Finally, we wish that Armstrong could have done a similar study on clean sulfur, which is a vital interest to the coal mines in the US. Her implied remark on sulfur in the concluding section of the paper may turn out to be incorrect because our experimental variograms on clean sulfur at different density levels were even less satisfactory than those on recovery.

Jan 1, 1985

Simulator technology has advanced to the point where the cost of mining equipment simulators is beginning to make commercial sense. Simulator-based evaluation allows operators or potential employees to be assessed in a pseudo-real environment under surface and underground mining conditions. Simulator training also allows operators to be exposed to emergency and advanced situations such as brake or steering failure or a tireblowout. ThoroughTec, of South Africa, provides simulator equipment to the mining industry. The company’s various packages of simulator products provide an unbiased evaluation score that removes human error from the assessment process. This same evaluation score is also presented at the end of normal training or refresher training sessions. In this way, the simulator helps eliminate bad habits and improve efficiencies.

Jan 1, 2003

By M. P. Valoski

Mine fires and/or explosions continue to occur. While these are unusual events, they comprise emergency situations. Whenever one of these events occurs, the Mine Safety and Health Administration (MSHA) responds with specially trained teams, mine fire experts, sophisticated scientific instrumentation, and trained instrument operators. In order to analyze mine air samples on-site, because time is of the essence, MSHA has a Mobile Gas Laboratory. The laboratory, which is stored near Pittsburgh, is totally self-contained. Sending air samples to a laboratory would take too long. Mine fire experts need the results of the latest analyses as soon as they are finished. The mobile laboratory is housed in the box of a diesel truck. Benches line both sides of the laboratory. Gas chromatographs are mounted on the benches. There is sufficient bench space for multiple bench top gas chromatographs. These instruments and their controllers are shock and vibration isolated to protect them during transit. The mobile laboratory can operate using on board diesel generators or line power. An uninterrupted power supply (UPS) supplies power to the instruments while switching from generator to line power or visa versa. Therefore, analysis of samples can proceed without interruption if a power failure would occur. In the rear of the mobile laboratory are racks that hold compressed gas cylinders. These cylinders contain carrier gas and compressed air. An air compressor is housed under the laboratory to operate the gas chromatograph actuators. Within several hours after arriving at a mine the instruments have stabilized and have been calibrated. The mobile laboratory is ready to begin analyzing air samples. The mobile laboratory has proved itself at many mine fires and explosions since its purchase.

Jan 1, 2009

By B. Slaker

The ability to detect and quantify ground movements in underground mine workings is of the utmost importance to the safety of miners and continuity of operations. Rib sloughage is one of the most common forms of underground deformations. Remote sensing techniques, such as laser scanning, can be used to quantify this rib sloughage, by recording precise, time-lapse point clouds of mine workings. In order to determine sloughage volumes and locations, a total of 11 laser scans were performed 41 days apart at a working section of an underground limestone mine. During this period, significant sloughing and scaling occurred, allowing for differentiation between the initial and final point clouds.

Feb 27, 2013

By Steve Kral

For an industry that provides more than half of the nation’s energy needs, the U.S. coal industry still attracts negative publicity. However, the nation’s energy appetite continues to increase. And political leaders and the public are beginning to understand that alternative fuels will not be enough to keep up with that appetite. Does that mean the nation will now embrace the coal industry? No, according to speakers at the Rocky Mountain Coal Mining Institute (RMCMI) meeting. The industry still needs to sell the public on coal’s advantages over other fuels. And the industry must continue to develop technology that will allow coal to meet and exceed strict clean air and clean water regulations.

Jan 1, 2002

By Adriaan de Villiers

Many conventional structural analysis and design methods in current use are not appropriate for the mining industry. Two major reasons for this are that: • The economic life of a particular mine is limited, and • Much of the equipment and machinery used by the mining industry operates at relatively low speeds. Both of these factors can have significant cost implications if they are not properly accounted for during plant design. In particular, the often used practice of mitigating excessive vibration by adding mass to machinery supports is not only expensive but may worsen the vibration effects. Some of these problems, such as increased wear and tear, are not always easy to trace back to inappropriate design. This article focuses on vibration related issues and demonstrates that the mining sector has unique problems requiring unique solutions. Vibration: the basics Historic developments leading to current vibration design practices provide the key to why such practices are often inappropriate for the mining industry. To understand this, it is necessary to introduce some basic vibration theory. Consider a simply supported beam or foundation on which a vibrating machine is mounted. For analysis of the system's dynamic response, it may be viewed as a mass attached to a spring and a damper, such as the shock absorber of a car.

Jan 1, 1992

By W. L. Jacobsen, T. L. Dyer

Cortez Gold Mines is completing a Feasibility Study for a new open pit gold mine in north central NV. The production schedule calls for a peak in material movement. This schedule is based on current operational efficiencies and equipment parameters observed at the company’s existing open pit operation. To mitigate risks of over/under predicting production, simulation modeling was used to validate the loading and haulage requirements during the peak production period. The advantage of simulation is the ability to provide a realistic model of a mining operation based on scheduled, and unscheduled random events during the period under analysis.

Jan 1, 2006

By David Burgess

The paper describes experiments at the Somerset Mine, Colorado, under a cooperative agreement between U.S. Steel and the U.S. Bureau of Mines. A test was made of the tube bundle method of mine air sampling which was developed for European longwall mines; some 300,000 running feet of tubing provided continuous monitoring at 39 locations. Carbon monoxide concentrations were obtained with standard deviations of less than 1 ppm and oxygen concentrations with standard deviations of less than 0.20 percent. A base level of CO index (ppm CO evolved/pct 02 removed)) was determined to be 0-20 through most of the passageways of the mine. However, in one working section where the coal was initially hot (about 180°F within a pillar) the CO index was demonstrably higher, >20 trending upward to about 60 when smoke appeared and the section was sealed. The data are discussed in terms of laboratory experiments on CO evolution from coals.

Jan 1, 1975

By Ulf G. Gwildis

The Bright water Conveyance System includes 21 km of tunnels mined by two earth pressure balance Tunnel Boring Machines (TBMs) and two slurry TBMs. The probabilistic baseline approach defined in the Geotechnical Baseline Report (GBR) can representatively be verified by use of a comprehensive tracking system to identify face conditions that allows comparison with the baselines. The glacial geology includes a high lateral variation in soil types that, when combined with the pressurized face tunneling methods, creates challenges for documenting face conditions. Baseline tracking using spoil samples and TBM operational parameters provides information to document actual conditions and support resolution of differing site condition claims.

By M. Karmis, S. K. Weisiger

The traditional method for training personnel in the mining and other heavy industries has been face-to-face, either via a lecturer in a classroom or through an apprenticeship. With the advent of applications tools such as video, computers, and the Internet, however, a much broader range of training delivery methods is available. Especially exciting are the broad capabilities of multimedia packages that combine the best features of numerous delivery methods. Applying multimedia environments in training holds great potential, especially when there is considerable difficulty in reconstructing real training environments. The authors discuss various delivery methods currently used in training employees, including perceived advantages and disadvantages of those methods. The authors then discuss and evaluate current computer-based training efforts of the mining industry and present an example of a multimedia training tool.

Jan 1, 2001

By T. E. Bernard

Occupying a refuge alternative (RA) is an accepted practice in mine fires and explosions when escape is not feasible. MSHA has promulgated a final rule on refuge alternatives that includes a recognition that thermal environment is an important consideration. To this end, an environmental index was specified. The question remains about how to test a refuge shelter to demonstrate that it meets the final rule. The analysis followed five activities: A. Provide an estimate of heat generated by an individual refuge alternative occupant; B. Evaluate the Steadman Apparent Temperature criterion of 95°F; C. Discuss simulations based on body temperature or skin temperature limits; D. Suggest method of simulating human heat generation during refuge occupancy; and E. Suggest alternative methodologies/criteria for evaluating heat and humidity survivability inside a refuge alternative.

Feb 27, 2013

By S. Sunkavalli

Acid rock drainage (ARD) is produced when sulfides are exposed to oxygen and water. Oxidation reactions typically result in a depression of pH and leaching of solutes and metals. Many oxidation models have been developed based on oxygen diffusion, but in environments with high permeability, other transport processes (i.e., convection and advection) can play an important role. Multiple sulfide mineral phases with differing oxidation rates should also be incorporated. WROC, a finite-difference model, was developed to account for these factors in predicting ARD. The program includes sulfide mineral oxidation using a shrinking core mechanism, heat transfer by conduction, heat of reaction, and oxygen transport by diffusion and advection. The model was validated using data from the literature. After validation, the WROC model was used to simulate several different waste rock scenarios including different forms of sulfide mineralization and the effect of implementing a waste rock cover. The results demonstrate that including specific sulfide mineral phases can have a significant effect on oxidation and that implementation of a cover can also aid in reducing waste rock oxidation. Key words: Arsenic sulfides, oxidation, shrinking core, waste rock, oxygen transport

Feb 27, 2013

By David Chapman, Glen Frank

Due to the transport mechanics of the depositional environment, glacial soils display a very wide range of grain sizes and behavior. Several nonstandard drilling, sampling, and analytical techniques are therefore required to characterize the subsurface. The paper summarizes the geotechnical investigation for the design of a large project in glacial geology, which will include both large and small diameter pressure balance tunneling. The paper focuses on the challenges presented by the glacial environment and the techniques required to identify and characterize it for design and contract document preparation.

Jan 1, 2001

By K. Fleck

Energy West Mining Company (EWMC) has implemented a geologic program for improving stability and support requirements along deep two-entry longwall gateroads at its Deer Creek Mine operations located near Huntington, Utah. Together with geotechnical monitoring and concurrent review of mine seismicity in cooperation with MTI staff, it has become possible to improve longwall layout designs for two seam extraction of the Hiawatha and Blind Canyon seams. The geologic program consists of surface and in-mine exploration drilling, surface and in-mine geologic mapping, rock mechanics testing and detailed measurements of changes in depositional and structural conditions during development of every longwall gateroad. The geotechnical program consists of underground measurements at seven locations in two neighboring mining districts located in the Hiawatha and Blind Canyon coal seams under moderate to deep cover. Within the last five years, additional measurements, including data on seismicity and face conditions, have been incorporated into the data collection program for verifying the insitu coal strength and load transfer mechanisms for improving two-seam designs and support systems. Geologic mapping results are also used to predict local stability of headgate and tailgate entries, combining mine roof mapping, stratigraphic profiles of the coal and roof, and depth-of-cover information and dual-seam mine overlays, for use by operations personnel in planning roof and rib support for the retreating longwall sections.

Jan 1, 2012