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By O. MacIntosh

The Round Mountain gold mine, located 90 km (55 miles) north of Tonopah, Nevada began large-scale production in 1977. During 2008 Round Mountain Gold Corporation (RMGC) relocated the primary crusher facility approximately 300 meters (1,000 feet) to make room for the next phase of open pit mining activities. This facility was installed in 1988 and used a log-crib retaining wall and dump pocket RMGC selected Hilfiker Retaining Walls and Collins Engineers, Inc. to provide design and materials for a new 17 meter (56 feet) high Mechanically Stabilized Embankment (MSE) wall to support the haul trucks at the new location. The construction contractor was EarthTech West Ltd. of Norwood, Colorado. An MSE wall with a cast-in-place concrete face was chosen as a durable, yet less expensive alternative to the reinforced concrete dump pocket that was originally designed for the project. The arrangement of the MSE wall is of an unusual configuration to meet a variety of operational and maintenance requirements. This paper outlines the selection process, design, and construction of the MSE wall.

Jan 1, 2009

By Nilabjendu Ghosh, Satyendra Kumar Singh, Gautam Banerjee, Harshit Agrawal

High-production methods like longwall mining with hydraulic powered supports are necessary to increase underground coal production in India. Longwall mining had a mixed success record for Indian geo-mining conditions. In this paper, an analysis is presented to optimally design an array of chain pillars in multi-seam longwall mining panels in the deepest coal mine in India. The study found that a chain pillar of 80-m width and 195-m length is necessary for long-term stability without any reinforcement. It was also observed that an optimum chain pillar can be designed by providing suitable side reinforcement (side bolting) which will reduce the chain pillar dimensions to 55-m width and 160-m length. Optimum design of chain pillars will reduce the coal locked up in these chain pillars by ~ 77%. This will also reduce the gestation period of longwall mining panel development. This paper also evaluates the maximum tensile subsidence strain induced at the surface and finds that the values are within the safe working limit of 3 mm/m. Thus, this paper finds direct application in the design of future multi-seam retreating longwall mining panels in Indian geo-mining conditions.

By Joseph Clare, Elizabeth Anderson, Mike McGinley, Ron Hines, Judy Cochran

The South Lake Union Pipelines contract for King County Wastewater Treatment Division and Seattle Public Utilities in Seattle, Washington included three 1.8 m (72-in)inside diameter microtunneled pipeline segments totaling about 793 m (2,600 lf).Tunnel alignments were within street right-of-way of heavily traveled urban roadways. Project challenges recognized in the design included: high groundwater levels; contaminated soil and groundwater; variable soil conditions, including fill; and timber piles and other obstructions remaining from historic land uses. The tunnels were built using a Lovat MTS Microtunneling machine, beginning in spring 2003. Conditions encountered during construction presented additional challenges beyond those anticipated in the design process, and were successfully addressed by the owners, designer, and construction management consultant all working with the contractor. Problems included highly variable soil conditions, cracking of reinforced concrete pipe joints during pipe jacking, a timber pile trestle uncovered during shaft construction, and obstructions encountered in the second and third microtunnel runs.

Jan 1, 2005

By William R. Bond, Jim V. Rouse

Introduction The pressure/vacuum (p/v) lysimeter or soil water sampler has become useful for monitoring vadose zone or unsaturated zone water conditions. The soil water sampler was first introduced around 1961. It was used as a monitoring and research device for studies in agriculture and soil contamination around landfills. Since then, it has been used for many purposes. The use of p/v lysimeters at mining facilities to monitor for solution loss is a relatively new idea. The primary purpose of the lysimeter here is to function as an early warning system. It detects leakage through liners of tailings ponds, heap leach pads, and leachate holding ponds. Their use has proven valuable for collecting baseline data and detecting loss of precious leachate fluid. Different lysimeter designs are capable of vadose moisture sampling from near the surface and down to 90 m (300 ft). They are also capable of sampling soil moisture or saturation plume contaminants from areas not accessible by conventional water well installations. The most common installations are usually simple and cost-effective. In many cases, they can be installed without the use of heavy drilling equipment. A properly placed and installed lysimeter can detect solution leaks in several days or weeks. A conventional perimeter monitor well may take months or years to detect a leak of the same magnitude. A discussion on the general design and installation of p/v lysimeters will give an understanding of its versatility. Three case studies of lysimeter installations at mining sites will be examined in detail. Design, Installation, and Sampling Design The basic design of a p/v lysimeter chamber consists of a porous material through which the soil is drawn into a collection chamber. Access tubes run from the unit to the sample station at the ground surface. Most units currently available range from 25 to 76 mm-diam (1 to 3 in.-diam). The sample collection chamber, or body, can vary from 0.6 to 1.8 m (2 to 6 ft) in length. The body can be constructed of PVC casing or Teflon, depending on the installation desired. The collection chamber functions as a holding reservoir for the collected soil moisture. The intake, or porous material, on the lysimeter is the most complex and vulnerable portion of the unit. The pore size selection varies based on the needs of the installation, type of fluid to be sampled, and type of soil material surrounding the unit. Teflon (PTFE) and porous ceramic are used in fabrication of the porous inlet portion. When using a Teflon material, which is hydrophobic, a larger pore size of 70 µm is needed to overcome surface tension and draw water into the collection chamber. It is typically used at sites involving organic contamination, because of its inert properties. Ceramic material is generally hydrophilic, having less surface tension. Therefore, it has a smaller porosity range to conduct the moisture through the porous medium while under vacuum. Pore sizes may be selected from 0.16 to 6 µm, and can be manufactured for the specific needs of the installation. The final major design component of the p/v lysimeter is the access or sampling tubes. The tubes are usually of 6.3-mm-outside-diam. (0.25-in.-outside-diam). They are made of rigid polyethylene or flexible Tygon with a wall thickness of 1.5 mm (0.06 in.). The con-

Jan 4, 1985

By F. J. Brenner

The Slippery Rock Watershed Coalition was organized to restore a 70 km2 portion of the headwaters of the Slippery Rock Watershed in northwest Pennsylvania. Thirteen passive treatment systems have been installed with engineering and funding provided by private industries, county government and the Commonwealth of Pennsylvania. In addition, experimental systems have been installed at the Jennings Environmental Education Center which, in addition to monitoring the systems installed within the watershed, provide an array of educational and research opportunities for secondary, college and university students. The coalition sponsors an annual seminar for students to present the results of their research and field trips for public officials and private citizens to learn how public and private partnerships work together to restore the Slippery Rock Creek watershed.

Jan 1, 2002

By Steven K. Duke, Jay Arabshahi

An economic, real-time probe drill monitoring system was developed for Metropolitan Water District’s Arrowhead Tunnels project to quantitatively evaluate ground conditions ahead of a TBM. This system digitally records hydraulic feed, rotation, and percussion pressures and calculates drill advance rates during drilling. These data are computer synthesized to develop a digital representation of the ground ahead, and the resulting “picture” of the ground is distributed to the project team to assist with tunnel construction decisions (i.e., targeting grout holes, optimizing mine-cycle lengths, and avoiding becoming stuck). The analysis and interpretation procedure has now been calibrated and refined using over 5,000 m (3 miles) of geologic face mapping data.

Jan 1, 2007

By Allan E. Koski

Ceveland-Cliffs uses a specialized software package in mine planning at the Empire Mine, an iron ore mine it manages on Michigan’s Marquette Iron Range. The application puts together years of mining experience that began in the early 1960s on the eastern end of the Marquette Range. The Empire Mine is in its 38th year of production. It uses the software to model a complex and highly variable low-grade magnetite ore body, capturing the economics of mining and processing to the final product. With special attention given to geostatistical methods, the software is used for all geologic modeling, ore reserve estimation, ore control, pit design and short- and long-range planning.

Jan 1, 2000

By D. Mohapatra

Extraction of Al(III) from aqueous sulfuric acid solutions into organic Cyanex 272®-carbon tetrachloride systems was investigated from a multi-component mixture containing aluminum, cobalt and nickel. Al(III) extraction efficiency was quantitative with 1.0 M Cyanex 272® in two stages at an aqueous: organic (A:O) phase ratio of 1:1 and an equilibrium pH of 3.2. The stripping of Al(III) from the loaded organic (LO) with different acids indicated sulfuric acid to be the best stripping agent. More than 99% stripping of Al(III) from the LO was achieved using 2 M H2SO4 at an A:O phase ratio of 1:1 in a single stage. The stoichiometry of the extracted species of Al(III) was determined by the slope analysis method. The extraction reaction proceeded via the cation exchange mechanism and the extracted species was assumed to be AlA3?3HA, where HA refers to the dimeric and A the anionic form of the extractant, Cyanex 272®. The extraction of Al(III) was studied in the presence of various ions to ascertain the tolerance limit of individual ions.

Jan 1, 2008

To simplify programming, image analyzers commonly measure either linear intercepts or the areas of particles and grains to determine liberation based on polished section mounts. However, the concentration of minerals by flotation is based on reagents that interact with the exposed surfaces of the minerals. Thus, it is often perceived that image analyzers should measure the perimeter of the mineral of interest in the ore particles. A comparative liberation study of thirteen samples collected from a flotation plant processing a complex base metal sulfide ore showed that the liberation of the ore minerals determined by area measurements is very similar to the liberation determined by the exposed perimeters. The liberation determined by exposed perimeters is more appropriate only for those cases where the mineral texture is so complex that it is retained in the small particles generated in conventional grinding operations.

Jan 1, 2002

By Darrell Gillis

Recent accidents in the United States underground Coal Mines and the on-going carnage in Underground Chinese Coal Mines has shown the danger associated with the lack of communication infrastructures in an underground environment. The US Mine Safety and Health Administration (MSHA) have introduced legislation that states all Underground Coal Mines must have two-way voice and personnel tracking capabilities by 2009. If Coal Mining companies are being forced to deal with this problem Tunneling Companies will not be far behind. This paper will examine current practices and best case technology to deal with these issues.

Jan 1, 2007

By Edward Thomas

Yucca Mountain Overview The U.S. Department of Energy?s Yucca Mountain Project is a geologic repository project designed to receive, handle, package, transport, and emplace spent nuclear fuel and high level radioactive waste. The planned repository would be located in Yucca Mountain on the western edge of the Nevada Test Site, about 90 miles northwest of Las Vegas, Nevada, and would include both surface and subsurface areas. Yucca Mountain rock formations consist of successive layers of volcanic rocks (called tuffs) approximately 14 to 11.5 million years old, formed by eruptions of volcanic calderas to the north. With the volcanic rock the potential for methane emission is not an issue and the subsurface repository is a non-gassy (methane) classification. This paper will provide a summary of the development ventilation system design that provides fresh air for subsurface construction activities, and the emplacement ventilation system design that removes heat generated by the waste packages. The subsurface layout, illustrated in Figure 1, contains 108 emplacement drifts, one Performance Confirmation(PC) observation drift, nine intake/exhaust shafts, and three access ramps. The existing Yucca Mountain facilities, shown in bold lines in Figure 1, include a 7.8 km long, 7.62 m (25 ft) diameter U shaped tunnel that is formed by the North and South Ramps at both ends of the Exploratory Studies Facility (ESF) drift and a 1.5 km long, 5.0 m (16.4 ft) diameter Enhanced Characterization of the Repository Block drift (ECRB) that were constructed from 1994 through 1998. These drifts were used for site characterization activities and have been incorporated into the subsurface repository configuration. The unexcavated perimeter access main and exhaust main drifts are typically 7.62 m (25 ft) diameter TBM excavations and the emplacement drifts are 5.5 m (18 ft) diameter TBM excavations. The turnouts leading into the emplacement drifts are to be excavated by either mechanical, or drill and blast methods and serve as the launch chambers for the emplacement drift TBM excavations.

By Ronald E. Heuer, Debra L. Virgens

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

Jan 1, 1987

The Barrick Zaldivar mine is an openpit, heap-leach copper mine in Region II of northern Chile at an elevation of 3,300 m (10,826 ft), approximately 1,400 km (870 miles) north of Santiago and 175 km (109 miles) southeast of the port city of Antofagasta. In 2006, Zaldívar produced 307 million lbs of copper, with reserves estimated at 5.7 billion lbs. The mine uses conventional methods of openpit mining: Pure cathode copper is produced by three stages of crushing and stacking the ore, followed by heap leaching and bacterial activity to extract copper from the ore into solution. A solvent extraction and electrowinning process then removes the copper from solution and produces the cathode copper. A flotation plant also recovers copper contained in the fine fraction of the crushed ore. In 2006, an existing A-frame structure that covered copper ore from the mine?s secondary crushing operation was damaged beyond repair. The material delivery configuration of this original structure had the conveyor carrying incoming ore directly over the low roof to drop ore into the building at its peak, and ore trickling from the sides of the conveyor had accumulated on the roof, overloading it. A better solution had to be found, and fast: First, the Chilean Commission does not permit uncovered piles of this type since the extremely fine material leads to serious pollution problems. Second, Barrick Zaldivar is very concerned about worker safety, and the amount of dust created by the uncovered pile was not acceptable. Finally, some amount of copper was lost in the dust generated by the winds of the Andes. The major issues faced by Barrick Zaldivar in designing a new structure included:

Jan 1, 2009

Lime production is the largest single chemical use for limestone and dolomite. The term “lime” in this review refers to high-calcium and dolomitic quicklime, their hydroxide forms and dead-burned dolomite. This review is restricted to a discussion of the U.S. lime industry. Production and consumption In 2004, according to preliminary data, U.S. lime production was about 20.1 Mt (22.1 million st), an increase of 900 kt (990,000 st) compared with 2003. Production in2004 was valued at about $1.4 billion. Commercial sales of lime totaled 18.6 Mt (20.5 million st) and captive production was 1.5 Mt (1.65 million st). Total U.S. consumption was about 20.2 Mt (22.2 million st). The majority of U.S. lime trade was with Canada.

Jan 1, 2005

By R. K. McLimans, C. Knudsen, S. Bernstein, D. Frei

Computer Controlled Scanning Electron Microscopy (CCSEM) is used to analyze indivdual mineral fractions in heavy mineral sands. CCSEM is a fully automated particle analysis technique for the determination of physical and chemical properties of a large number of individual particles. CCSEM enables the precise and accurate determination of the modal abundances of individual mineral fractions (e.g. ilmenite, rutile, zircon, or garnet), their average chemical composition (and compositional variation), as well as their physical properties such as size (e.g. diameter and perimeter length) and shape (aspect ratio and circularity). A unique sample preparation procedure is used to produce representative polished sections from cylinders of raw sand samples such that thousands of grains are present in a polished cross section, but grains are not touching. The combination of this sample preparation technique with CCSEM enables the fully automated analysis of individual grains without the application of de-agglomeration or erosion steps to separate touching particles. Hence, CCSEM yields information representative of the entire area of analyzed grains without systematic bias due to neglect of rim areas by de-agglomeration or erosion steps. Therefore, the resulting data are determined with high accuracy, precision and statistical validity. Because the sample preparation is relatively straightforward, using raw sand samples, and all chemical and physical properties are determined in one analytical session per sample, CCSEM is a powerful cost and time efficient tool for characterizing chemical and physical properties of minerals in heavy mineral sand deposits.

Jan 1, 2005

By A. Martikainen

Field tests concerning a fog mesh method for fog removal are discussed. The first tests were performed at the Pyhäsalmi Mine, Finland. As this study gave promising results, further studies were completed at the Orivesi Mine. The results of these most recent field tests are presented and the two studies are compared. The Orivesi test set consisted of four materials. These included air filter fabric, fibrous filter fabric, a plastic greenhouse mesh, and an aluminium mosquito net. The variation of the Orivesi results was more noticeable than what was found previously. The best fog removal effect of all tests was achieved with the aluminium mosquito net, while the plastic green-house mesh performed worst. The humidity reduction by aluminium net was more profound than any of its precedents. More mesh materials will be tested in the near future.

Jan 1, 2007

By S. Ersayin

In 1998, the Concentrator Modeling Center was established within the Coleraine Minerals Research Lab to develop models for simulation of iron ore processing plants, and to assist plant operators in improving performance of their aging plants. The short-term objective was to develop necessary models for reliable simulation using conventional techniques, while the long-term objective was set as liberation-based modeling and simulation of these plants. The short-term objective was achieved in 2002, after the development of models for magnetic separators, hydroseparators and fine screens. A project funded the US Department of Energy was carried out to demonstrate the capability in improving iron ore processing at the Mittal plant. As a result of this study, a 10% improvement in throughput at the plant was obtained, and simulation became a desired tool for plant operators. A significant step in the long-term objective was reached in 2005 with the development of a liberation model. This was followed by incorporation of models capable of processing liberation data into the software. By early 2007, the Center had the capability of performing liberation-based simulation of entire plants.

Jan 1, 2008

By L. F. Ruppert, W. D. Watson, S. J. Tewalt, L. J. Bragg

The U.S. Geological Survey recently completed a digital coal resource assessment model of the Upper Pennsylvanian Pittsburgh coal bed which indicates that of the original 34 billion short tons [31 billion tonnes] of coal, 16 billion short tons [14 billion tonnes] remain after subtracting mined-out coal. When technical, environmental, and social restrictions are applied to the remaining Pittsburgh coal model, only12 billion short tons [11 billion tonnes] are available for mining. Our assessment models estimate that up to 0.61 billion short tons [0.55 billion tonnes], 2.7billion short tons [2.4 billion tonnes], and 8.5 billion short tons [7.7 billion tonnes] could be available for surface mining, continuous mining, and longwall mining, respectively. This analysis is an example of a second-generation regional coal availability study designed to model recoverability characteristics for all the major coal beds in the U.S.

Jan 1, 2000

By Mikko Ruonala, Pertti Lamberg, Olli Hyvärinen

The smelting of copper sulphide concentrate is the dominant route in copper production (Figure 1). Heap leaching of oxidized copper ores with weak sulphuric acid together with copper solvent extraction and electrowinning has gained popularity during recent decades, and it accounts for close to 20 % of primary copper production. Heap leaching offers advantages such as lower costs and consequently the construction of a production plant at a mine site is made possible. Limited resources of oxidized copper ores, the long leaching time of chalcopyrite and inability to recover gold inhibit this growth. The HydroCopperTM process developed by Outokumpu Technology at the laboratories of Outokumpu Research, Pori, Finland, is a new chloride leaching technology /1,2/, which offers an alternative to smelting and heap leaching (Figure 1). In the HydroCopperTM process sulphidic concentrates with various mineralogy and grade can be treated at the mine site to produce high-quality copper. Instead of copper cathodes the HydroCopperTM end products are copper wire rod, copper bars or copper billets. One of the advantages of HydroCopperTM technology is that gold can also be recovered in the process simultaneously /3/. To confirm the functioning of the new process and to dimension equipment Outokumpu Technology built the HydroCopperTM demonstration plant in Pori, Finland /4/. It has a capacity of 1 metric ton of copper per day. After testing with Pyhäsalmi copper concentrate in 2003, the first commercial demonstration run with Erdenet copper concentrate took place in 2004.

Jan 1, 2005

By S. Chander, S. W. Musselman

The molecular structure of hydrophobic and hydrophilic groups in nonionic surfactants has been related to the wetting and dispersion of selected pigments. The nonionic surfactants included in this study are acetylenic diol based surfactants and ethoxylated alkyl phenols. The Langmuir model could be used to fit adsorption data. Further analysis of the data showed that the free energy of adsorption was a function of adsorption density of the surfactants at the interface. The change in free energy with adsorption density could be interpreted by considering a change in the orientation of the adsorbed molecules. Acetylenic diol based surfatants were found to have an area per molecule of 2-3 times that of similarly ethoxylated alkyl phenols. The wetting and dispersion properties of lamp black, a model hydrophobic surface, by these surfactants were investigated by contact angle measurements and particle size analysis. Acetylenic diol based surfactants with ethylene oxide contents between3.5 and 10 moles per molecule and alkyl phenol based surfactants with approximately 9 moles of ethylene oxide per molecule were found to provide superior wetting abilities. Longer ethylene oxide chains were required for superior dispersion capabilities within each family of surfactants. Complete wetting and dispersion was found to occur above the critical micelle concentration of the surfactants.

Jan 1, 2000