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By Martin Herrenknecht

The world?s growing population and rapidly proceeding urbanization are boosting an enormous demand for new and high-capacity infrastructures to secure the mobility of goods and people. Densely populated areas face the challenge to provide efficient traffic infrastructure, such as a modern public transportation system. At the same time, the maintenance and modernization of supply and disposal structures for water, sewage, energy and communication are also essential. Additionally, supra-regional transportation routes such as long distance water diversion schemes are the challenges for the future. All these projects are as demanding as they are characterized by a tight time schedule.

Jan 1, 2010

By Beverly Cramp

In 1995, mining engineer Alain Gachet thought about using Earth-observation satellite imagery to search for precious minerals. The latest radar Earth-observation satellite, Canada’s RADARSAT-1, had just been successfully launched at the time, creating new opportunities for commercial applications. Gachet was working in Congo Brazzaville as an oil executive and general secretary of Elf Congo for the French national oil company Elf Aquitaine. He understood that the RADARSAT-1 launch promised new and cost-effective sources of data for mineral and oil exploration. “It was early 1996 before I ordered my firstRADARSAT-1 satellite images,” said Gachet. “I was first struck by the quantity of information delivered by the radar images. Linear structures and faults were clearly defined and subtle topographic features were tremendously enhanced,” he said. “It was ‘tree top geology,’ but this kind of information appeared to be key for finding new gold seams.”

Jan 1, 2003

By Shaoxian Song, Ling Xia, Hongqiang Li, Yubiao Li, Yunliang Zhao, Shaobing Xie

Since human daily demands for fresh water have been increased significantly, the supply of fresh water for the mining industry, especially froth flotation, should be considerably reduced. In addition, stricter environmental standards have been implemented in many countries to reduce the risks due to the disposal of wastewater, many flotation operators have to seek more efficient ways to utilize the limited fresh water sources. Recycling water with high concentrations of impurities is a normal strategy for most of the mineral processing plants; however, water quality should be carefully considered to guarantee a smooth flotation process. Recently, the application of seawater in flotation has attracted much attention due to its availability and abundance rather than fresh water. However, the influencing mechanisms due to the application of seawater in flotation have not been fully understood especially the reactions between mineral particles and bubbles in the presence of high concentrations of cations and anions. This would impede the application of alternatives to fresh water in the flotation. Therefore, this paper reviews the current water sources and the technologies for water recycling in the flotation process. Specifically, the life cycle of water in flotation was proposed. In addition, the strategies including high pulp density flotation as well as the most promising alternatives to fresh water have been discussed in details, with the related mechanisms being demonstrated.

By A. Jarosz

The surface manifestation of underground mining usually entails five distinct types of surface movements, which can affect or damage surface structures, facilities and renewable resources. These movements developing at the surface can be described by (Bell, 1975; Bhattacharya and Singh, 1984): - vertical displacement, i.e. subsidence, - horizontal displacements, - slope or tilt, i.e. the derivative of the vertical displacement with respect to the horizontal distance, - curvature, i.e. the second derivative of the vertical displacement with respect to the horizontal distance, and, - horizontal strain, i.e. the derivative of the horizontal displacement with respect to the horizontal distance.

Jan 1, 1986

By Wayne E. Kilker, Michael J. McBride, William P. Levy, Thomas J. Lamb

Between 1989 and 2004 the Massachusetts Water Resources Authority (MWRA)constructed several major wastewater and water tunnels associated with three major projects in the Boston area of eastern Massachusetts. There were many similarities and differences in the bedrock conditions encountered and among the contractual approaches for these independent projects. Through a clarification of the approach similarities and analysis of the contract differences, this paper addresses and presents what are considered to be valuable lessons learned. In doing so, the paper follows the evolution of such disparate issues as contract conditions, baseline reports and dispute review boards. The authors believe that the lessons learned even represent what, in certain cases, could be referred to as “universal truths” that are intended to have application to the next generation of tunneling contracts.

Jan 1, 2005

By Ying Lu, Jeffrey C. Johnson, Chen-Luh Lin, Jan D. Miller, Sindhoora Puvvada

Energy dissipation and fragmentation of rock is of interest for mine-to-mill operations in order to understand breakage and to minimize energy consumption during blasting at the mine site, and comminution at the processing plant. In this regard, high velocity impact breakage of long granite cores, called bars, has been studied with instrumented strain gages to follow the energy dissipation gradient along the bar length resulting from the strain waves generated by impact. As a result of high velocity impact, three zones have been identified (fragmentation, fracture, and elastic) and these three zones have been characterized in 3D using X-ray tomography. The fragmentation zones of the granite bars were studied in detail to describe the particle size distribution and the particle shape characteristics. Finally, the experimental energy dissipation for the fragmentation zone was found to be in close agreement with the expected energy calculated from the Bond work equation, if the anisotropic granite particles are defined by length rather than by sieve size.

By Ying Lu, Jeffrey C. Johnson, Chen-Luh Lin, Jan D. Miller, Sindhoora Puvvada

Energy dissipation and fragmentation of rock is of interest for mine-to-mill operations in order to understand breakage and to minimize energy consumption during blasting at the mine site, and comminution at the processing plant. In this regard, high velocity impact breakage of long granite cores, called bars, has been studied with instrumented strain gages to follow the energy dissipation gradient along the bar length resulting from the strain waves generated by impact. As a result of high velocity impact, three zones have been identified (fragmentation, fracture, and elastic) and these three zones have been characterized in 3D using X-ray tomography. The fragmentation zones of the granite bars were studied in detail to describe the particle size distribution and the particle shape characteristics. Finally, the experimental energy dissipation for the fragmentation zone was found to be in close agreement with the expected energy calculated from the Bond work equation, if the anisotropic granite particles are defined by length rather than by sieve size.

By A. L. Martikainen

In fluctuating airflow, continuous air velocity recording is the most reliable method of air velocity measurement. It allows for fast recognition of changes and the calculation of long-term averages. Also, it enables the mine operator to identify when the airflow has decreased to a point requiring action. Using ultrasonic anemometers provides an accurate option for continuous air velocity monitoring. This paper provides information about the effect of common obstructions in underground mining on air velocity readings. Stationary and moving obstructions are used to represent workers and equipment that would cause discrepancies in measured airflow. Also, it is important to know how large of a sample size is required to ensure reasonable accuracy of results. Statistical analysis is used to evaluate the required sample size. The sampling procedure is further studied by comparing two different sample rates. The results show that obstructions provide noticeable differences in air velocity measurements. Also, movement of obstructions can be recognized from changes in results. Surprisingly small sample sizes provide reliable air velocity information. Standard sample rates are found to be suitable for the underground environment.

Jan 1, 2011

By Helmut Westermayr, Michael Tergl

DESCRIPTION OF PROJECT Geographic Setting The Kops II plant is a pumped storage scheme of the hydroelectric power producer ‘Vorarlberger Illwerke AG’ which is currently under construction in the Austrian Province of Vorarlberg. The plant is located at the end of the Montafon valley and will be fed with water coming from the Silvretta mountain range (Figure 1) Description of Plant The Kops II plant shall be operated as a pumped storage plant with three highly flexible and quickly controllable power generating units. Each unit shall have a capacity of 150 MW and shall be equipped for both turbine operation and pump operation. The Kops II plant uses the existing Kops Lake as upper storage reservoir and the existing Rifa balancing reservoir as lower storage reservoir. All major plant components of the Kops II scheme are located below ground. Total investment costs areapprox. 360 million Euro. Construction Lots The construction works for the Kops II plant, which were subdivided into three lots, were launched in September 2004. It is planned that the first power generating unit shall go on line in the year 2007. The completion of the overall project and the operation start-up of the second and third unit are envisaged for the year 2008. Lot 1—Pressure Tunnel. The 5.5-km-long pressure tunnel forms the connection between the Kops Lake and the beginning of the pressure shaft. The tunnel was excavated by the use of a double-shield TBM. Lot 2—Pressure Shaft and Surge Chamber. The approx. 1.1-km-long pressure shaft was excavated by TBM, advancing from bottom to top. Featuring an inclination of80%, the pressure shaft overcomes a difference in height of approx. 700 m. Lot 3—Power House Cavern and Tailrace Structure. The power house cavern, which is being built approx. 150 m inside the mountain, forms the core of this plant. The power house is designed to accommodate three power generating units, and the transformer cavern is forseen to accommodate three transformer units. The tailrace structure serves the purpose of conveying the water to the lower storage reservoir during turbine operation and as water intake during pump operation (Figure 2).

Jan 1, 2007

By M. K. Mohanty, H. Akbari, L. A. Ackah

Dry separation was the predominant method of coal cleaning in the United States from the 1930s to 1980s. The application peak of dry separators for cleaning raw coal was in 1965, when about 23.1 Mt of cleaned bituminous coal was produced. The main advantage of dry coal cleaning is the elimination RIWKH GHZDWHULQJ VWDJHV DQG VLJQL¿FDQWO\ UHGXFHG moisture in comparison to wet processing. In addition, developed dust control systems have made dry cleaning method an environmentally friendly process. The largest air-based coal cleaning plant was built in Pennsylvania in 1968 and could clean 1,272 t/h of raw coal sized smaller than 19 mm. This was followed by a decline in dry coal cleaning to less than 3.6 Mt in 1988. Some of the main reasons that shifted coal operations IURPGU\WRZHWSURFHVVLQJZHUHWKHQHHGIRUPRUHHI¿FLHQW separations with lower density cuts, increase in raw coal surIDFHPRLVWXUHVSHFL¿FDOO\LQXQGHUJURXQGPLQLQJWRFRQWURO GXVW ¿QHUSDUWLFOHVL]HUHTXLUHPHQWV LQFUHDVHLQ¿QHVLQUDZ coal from underground mines, and health and safety concerns related to dust and noise (Arnold, Hervol and Leonard III, 1991; Miller, 2011).

By Lawrence M. Gochioco

One of the best kept technology secrets in U.S coalmining history involved a robust coal geophysics program used by a local coal company to detect and map various geologic anomalies and man-made structures ahead of mining for nearly 15 years. Several original mine plans were changed as a result of findings from two-dimensional (2D) and three-dimensional (3D) seismic data. They indicated the presence of geologic anomalies in reserve areas that could adversely impact future mine development and longwall production. By combining the surface seismic and exploratory drilling methods, the coal company learned how to properly leverage its risk by gathering a lot of useful subsurface information before making major commitments.

Jan 1, 2005

By Taehong Kim, Carl Pannuti, Nikolas Sokol, Walter Herrick

BACKGROUND This paper discusses work performed as part the rehabilitation of the gravity flow section of the New Croton Aqueduct (NCA) during an approximately two year period between 2004 and 2006. The goal of the project was to restore the gravity flow section of the NCA to optimal operating condition, extending the lifespan of this significant water supply for the New York City metropolitan area. Rehabilitation of the NCA was purposely scheduled before the completion of the new NCA Water Treatment Plant now under construction (Figure 1). The NCA is a 3.73 to 4.34 m (12.25 to 14.25 ft) diameter brick-lined circular andhorseshoe shaped water tunnel constructed between 1885 and 1891. The NCA conveys water for approximately 50 km (31 miles) by gravity and pressurized flow from the New Croton Reservoir in Westchester County, NY to distribution and reservoir points along its alignment, terminating at a distribution station at 135th Street and Convent Avenue in Manhattan, NY. Prominent features of the NCA include a large intake facility at New Croton Reservoir, 38.6 km (24 miles) of gravity flow horseshoe shaped aqueduct, 11.3 km (7 miles) of pressurized flow circular aqueduct, 2 siphons, and 36 open shafts and headhouse chambers which are used as sampling, access and blow-off locations. Until a partial inspection in 1982, the NCA had flowed continuously since its completion nearly 100 years prior. Flow tests have confirmed that the NCA can convey up to 12.7 m3/s (290 mgd) (Figure 2). Cover depths of NCA vary considerably, ranging from a few to hundreds of meters, typically of hard rock. Primarily mined using means conventional for the late1800s, construction of the NCA also employed cut and cover methods in several low-lying sections of the alignment, totaling approximately 1.6 km (1 mile). The NCA crosses through numerous lithologic changes, fault/shear zones and under several significant water bodies including the Pocantico, Saw Mill and Harlem Rivers and the Tarrytown Reservoir. The NCA passes under the Harlem River as a siphon at a depth of approximately 122 m (400 ft) below grade (Figure 3). Soon after construction the Aqueduct Commission Reports on the New Croton Aqueduct documented prominent defects such as large voids behind the lining. More recently, large-scale inspections of the gravity flow section performed during the 1990sand a 2004 inspection of portions of the pressurized sections of the NCA have revealed additional defects such as open and/or deteriorated masonry joints/cracks, leaks ranging from trickles to several liters per minute into and out of the NCA, missing bricks, formed openings, and in one place, a rupture through the liner with discernable

Jan 1, 2007

By Carmel Bofinger, Maureen E. Hassall, David Cliff, Eric Stemn

e Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

By M. L. Free, L. Anthian

Electrochemical, chemical, and image analysis techniques were utilized together with statistical analysis methods to determine the effect of various anode impurities on copper electrorefining performance. Results indicate that arsenic is a beneficial anode impurity. Anode lead and sulfur are shown to decrease electrorefining performance. Specific emphasis is given to the influence of individual elements on current efficiency, slime particle generation, and cell voltage parameters.

Jan 1, 2000

By T. Bajpayee, J. Ellenberger

Microseismic monitoring and evaluation is one aspect of the National Institute for Occupational Safety and Health (NIOSH) research program. Roof falls are often preceded by a period of elevated microseismic activity, but not all periods of elevated activity result in a roof fall, nor do all roof falls occur after some amount of elevated activity. The objective of this study is to review periods of elevated microseismic activity and determine whether fracture activity rate can be used to anticipate the initiation of roof falls. The study was carried out at an underground limestone mine where major roof falls are associated with excessive horizontal stress. The progression of roof falls was detected by the microseismic signature produced by the rock falling from the mine roof onto the mine floor, which is termed a roof fall impact event. A total of nine elevated fracture activity periods that resulted in seven major roof falls were examined. It was observed that elevated fracture activity preceded the initial roof fall impact event in three out of four major roof falls. The initial impact event was not identified for the remaining three roof falls. Fracture event rates were analyzed and a roof fall alarm trigger of five fracture events in a ten minute time period was established for this test case. The fall alarm trigger was tested against six of the elevated activity periods. Four roof falls occurred in the six periods of elevated activity, and two would have triggered the alarm before the roof fall occurred, while two false alarms were generated. The results show that limited success would have been achieved by the microseismic system as a roof fall alarm trigger. However, the trigger would have been successful at warning of the onset of elevated activity, allowing mine employees to respond appropriately. The study highlighted some issues with implementing such a system in an operating mine, including the need for real time identification of fracture related microseismic signals among mining induced signals, and accurate location and identification of fracture clustering.

Jan 1, 2007

By Carmel Bofinger, Maureen E. Hassall, David Cliff, Eric Stemn

e Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

By Kirsten Corin, Belinda McFadzean, Cyril O’Connor, Jenny Wiese

The Bushveld Complex of South Africa contains almost 90% of the world’s reserves of platinum group minerals (PGMs). In the flotation of PGMs, there are significant challenges arising from the need to treat ever-decreasing grades of the relevant ore deposits. The major challenge in the flotation of these ore bodies is the control and management of the gangue minerals, particularly silicates such as orthopyroxene, plagioclase feldspar, and pyroxene which are often rimmed with talc which makes them naturally floatable. It has been shown that various polysaccharide depressants such as CMC and guar have different properties in terms of depressing the gangue minerals. Since the PGMs are often associated with sulphides, copper sulphate is widely used as an activator in PGM flotation but can inadvertently activate the gangue minerals as well as reduce the recovery of PtTe2 which accounts for up to 40% of the Pt in the Platreef ore body. Depressants also reduce the mass of solids reporting to the froth and can thus destabilise the froth. This effect on the froth can be mitigated by using higher frother dosages or water of higher ionic strength. Reducing chromite recovery is of critical importance since high levels may negatively affect the downstream smelting process. Chromite recoveries can however be reduced through the application of gravity separation or reducing entrainment through reduced water recovery. In summary, due care needs to be taken to carry out site test work to develop an optimum ratio of collector, frother, activator, and depressant to ensure that the highest grades and recoveries of the PGEs are obtained while reducing depressant dosage as much as possible.

By Wayne Trudel, Eric Saderhold, Lloyd McEvers, Lori Clarke, Charles Lynn Bolin, Leroy Schutz

Editor’s note: This is the second part of a two-part series on how mine geologists added about 141t (4.53 million oz) at Newmont Mining’s gold operations in Nevada during 2003. Part one (ME, July2004, pp. 19-26) showed how cross-functional teamwork among mine geologists, engineers, metallurgists and operators added $65 million in revenues at Newmont’s Gold Quarry Mine. Part two deals with how this same cross-functional team added about 25.8 t (830,000 oz) of gold reserves and two years of life at the company’s LoneTree Mine. This was done through improved reconciliation methods, pit optimization designs and updated geotechnical parameters. Part two also discusses how Newmont’s Nevada mine personnel added about 62.2 t (2 million oz) of gold reserves at its Twin Creeks Mine, extending the mine’s life by several years. The Lone Tree Mine is a sediment-hosted, micron gold deposit. It is dominantly situated in the Golconda thrust footwall. The north-south trending Wayne Zone fault controls the highest-grade ores and

Jan 1, 2004

By M. Dobbins

The advent of the more efficient and effective rare-earth roll (RER) separator in the early 1980?s began a new era of dry magnetic separation. The RER units quickly became the separator of choice within the materials processing industry. Though RER separators are now commonplace throughout the world, only modest advancements have been made to the original design. This paper details recent, more significant, rare-earth magnetic separation developments. These developments maintain the best features of existing technology while minimizing shortcomings. The discussion includes discerning features that aid in better metallurgical performance. Also discussed are improved mechanical aspects that allow for both easier operation and maintenance. Performance details from various test programs are included.

Jan 1, 2009

By D. Newman

Multiple seam mining is prevalent in Southern Appalachia because economically mineable coal seams are numerous and frequently occur in close vertical proximity. West Virginia, Kentucky, and Virginia have 117, 55, and 40 mineable coal seams respectively. It is extremely rare to have an underground mine that has not been undermined, overmined, or has mining adjacent to it. In many cases the multiple seam mining is concurrent with extraction sequenced in superjacent seams. Because underground mining is focused on recovering the most valuable reserves, mining is rarely practiced from the top seam down, which is the practice most conducive to stability. The combination of room-and-pillar mining methods that include development only, small block, partial retreat, full retreat, and longwall mining produce a wide range of mining geometries and complexity in underlying and overlying seams. In the future, the number of multiple seam operations will increase as reserves are depleted and future mines are, by default, located closer to abandoned mine workings. The improved coal market has transformed many formerally uneconomically mineable seams into attractive reserves. The approaches and methodologies used for multiple seam stability analysis are dictated by the site conditions, including overburden/interburden thickness and lithology, mining geometry, and the mining methods in both the active and abandoned mines. Multiple seam stability analysis using analytical and numerical methods is illustrated by two case histories that reflect close proximity room-and-pillar mining and mining in bump prone situations.

Jan 1, 2007