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By A. Iordanidis

Mining activities have recently been taken place in Vourinos mountain, northern Greece, exploiting the so-called ?olivinite?. A representative sample was collected from this mining area. Mineralogical analysis was conducted using X-Ray powder Diffraction (XRD). A thin section was prepared and analyzed under optical microscope. X-Ray Fluorescence (XRF) was employed for the chemical analyses of major, mi-nor and trace elements. Environmental Scanning Electron Microscopy coupled with energy dispersive x-ray analysis system (ESEM-EDX) was also applied for the characterization of the sample. Forsterite (Mg-rich olivine) and enstatite (Mg-rich orthopyroxene) were the main mineral phases determined by XRD, with a 56% and 44% content respectively. Trace amounts of chromite spinels were also determined. Based on this characterization, the industrial rock proved to be a hartzburgite (a type of peridotite in petrological terms). Optical microscopy and ESEM-EDX provided similar observations and confirmed the above-mentioned results. XRF revealed a composition of 43.31 MgO, 44.25 SiO2, 9.98 Fe2O3, 1.40 CaO, 0.67 Al2O3, 0.22 MnO, 0.01 TiO2 and negligible amount of LOI (<0.1%). Trace elements with high concentrations were Cr (2678 ppm) and Ni (2044 ppm). The comprehensive characterization of this mining product suggested the suitability for various uses, such as refractories, foundry and slag conditioner. Additional experiments are being carried out for environmental applications, e.g. wastewater treatment.

Jan 1, 2006

By Charles A. Edwards, Kenneth D. Merrill

The Construction of the Northeast Extension of the Baltimore Metro involved soft ground, compressed air tunneling. During the tunneling, gasoline and dry cleaning fluid contamination were encountered. Innovative approaches and solutions were developed to address these problems. Special emphasis was on the problem of compressed air pushing gasoline vapors into surrounding communities, resulting in an extremely dangerous situation and a public relations nightmare. Guidelines and standards were established for working in this contaminated environment. Also, through a proactive approach by all parties, all claims and disputes have been resolved.

Jan 1, 1995

By Dave Rogstad

The DART NC-1B Tunnel Project consists of two 5,100 m TBM excavated tunnels, a principal underground station, a partially completed future station, a surface station, and eight associated ventilation shafts and exit tunnels. This paper presents a case history of the project&apos;s construction, and will focus on six topics that give this project a unique and unusual history; the TBM excavation, two major differing site conditions, roadheader excavation, polyfiber reinforced shotcrete lining, the NATM design geometry, and a design/build type of contract.

Jan 1, 1995

By Kurt Egger, Emily A. Baker

Rehabilitation work at the Cameron Run Tunnels entailed the restoration of seven heavily deformed, approximately 69 m long, steel liner plate supported culverts through a CSX Railroad embankment near Alexandria, Virginia. A custom fabricated expander, equipped with four 200-ton hydraulic jacks on two expansion arms was used to push back the liner plates encroaching into the proposed tunnel profile and install the steel set support. In a second phase the tunnels were then lined with 16 cm of fiber reinforced shotcrete. Geotechnical instruments both in the tunnels and on the railroad embankment were used to monitor the effects of the rehabilitation work on the two CSX Railroad tracks above the tunnels. Freight and passenger trains were required to run uninterrupted and at maximum speeds throughout construction.

Jan 1, 2003

By Thomas R. Yanske, Jonathan E. Carmack, Lyndon M. Clark

In order to maximize the extraction of high grade pillars at The Doe Run Company, artificial pillars are created using cemented rock fill (CRF). CRF pillars aid extraction of pillars in two ways. One is to offer back support for the immediate area where pillars are being extracted. The second is to increase the post failure residual strength of pillars surrounded by backfill. The CRF is produced using a combination of minus 1.0 m run of mine (ROM) rock and minus 5 cm crushed rock. Depending on the operation the CRF slurry is either produced in an underground or a surface batch plant. The slurry and rock are transported to the fill area by truck where they are mixed and placed in 1 m lifts. To reduce the amount of CRF needed, fill fences are constructed around the perimeter of the CRF pillar. Within these fences ROM CRF is placed in lifts until within 0.6 m of the back after which minus five centimeter CRF is slung tight to the back utilizing slinger trucks. In constructing these artificial pillars a number of set procedures have been established to ensure that the work is done both properly and safely.

Jan 1, 2001

By R. A. Pond

Two 6.17 m (20 ft 3 in.) diameter raises, concrete-lined to 5.49 m (18 ft) inside diameter, were completed in 1978 at the Monterey Coal Company Number One Mine near Carlinville, Illinois, by Frontier-Kemper Constructors. These two raises are the largest in cross-section yet completed by full-face upreaming, and the success of this project is expected to increase the application of raise-boring to coal mine shaft construction. WHY 6.17 M (20 FT) DIAMETER ? Raise boring is well accepted in the metal mining industry for a variety of applications, and is gaining in acceptance in the civil works construction industry. The use of raise boring to construct vertical openings for coal mines has not been as widely accepted, even though coal mining requires, per mine, the greatest number of openings to the surface of any underground activity. Several factors have influenced the low utilization of raise boring in coal mining: 1. Coal mine shafts must often be of large diameter to pass the required high volumes of ventilation air at acceptably low water gage pressures. Cross-sectional areas of finished shafts exceeding 23.23 sq m (250 sq ft) are common. 2. The life of ventilation shafts is comparatively long, and the typical sedimentary strata overlying coal seams normally require that the shafts be lined. Shafts on the intake ventilation circuit must have permanent water-tight linings. 3. Unconsolidated overburden at the surface is often thick, and as reaming cannot be safely utilized in unconsolidated material,

Jan 1, 1979

By Brian S. Prosser, Ian J. Duckworth

With the trend in the coal mining industry pushing towards improved productivity and greater production, the number and size of longwall panels is increasing rapidly. The development and mining of large longwall panels causes unique problems in the provision of adequate ventilation at the working faces. Because of the transient nature of the longwall panel, and the difficult field conditions for ventilation measurements, detailed pressure and volume surveys are often not conducted around the longwall circuit. This is unforlunate because the highest resistance airway in longwall mines is typically the longwall tailgate, which frequently represents the only unregulated split in the ventilation network. This paper examines data collected from ventilation studies of longwall panels at nine mines. The variation in airway resistance, ventilating pressure and airflow is examined and compared with specific factors such as airway dimensions, ground conditions and support type used.

Jan 1, 1997

By Robert B. Gordon

The Reverse Curve Tunnel Project was located in Glenwood Canyon, Colorado approximately twelve (12) miles east of Glenwood Springs. The Project was one of many being constructed over a period of time by the State of Colorado, Department of Highways to improve Interstate 70 to four lanes as it travels thru the environmentally sensitive Glenwood Canyon. The Project consisted of excavating and concreting a tunnel approximately five hundred fifty (550) feet long, forty two (42) feet wide, and thirty two (32) feet high. The designer was Parsons, Brinkerhoff, Quade and Douglas, with geotechnical consultation provided by Woodward Clyde. CONSTRUCTION CHALLENGES There were several significant construction challenges presented primarily by the physical location of the Project. In this study each problem will be discussed, as well as how it was overcome by construction methods and/or design requirements. Portal Excavation - One of the most difficult areas of work on the Project consisted of excavation and stabilizing the East and West Portal rock prior to tunnel excavation. The Reverse Curve Tunnel passes through a sheer walled cliff face which is approximately two hundred fifty (250) feet high. Geologically the cliff consists of primarily sedimentary deposits with open, weathered joints and vertical faulting. Before the tunnel excavation could begin, a narrow sliver cut had to be excavated and rock

Jan 1, 1989

By Mathew B. Revell, Martyn L. Bloss

The paste fill system at BHP Cannington&apos;s underground silver-lead-zinc mine is described. The paste fill system has been operational since December 1997 and is the first of its type in Australia. Technical and operational learnings since stope filling commenced are presented. Topics described include plant performance, reticulation system design and construction, pipe wear and failure, rheology, in situ performance and laboratory testing.

Jan 1, 2001

By Kerry Burns

Contrary to active subsidence, which occurs concurrently with mining operations, or is completed within a few days following coal extraction, delayed subsidence may take many years to appear at the surface after coal mines are abandoned. There are two principal morphological types of delayed subsidence: troughs, which are shallow depressions, and sinks, which are steep-sided crown pits. Both types are damaging to surface structures, and a variety of methods have been introduced to deal with the problem, ranging from subsidence insurance to site restitution. In planning insurance or restitution measures, a predictive model is of value in estimating the magnitude of the problem and the size of long-term budgetary commitments. Only one model is known, which was developed for the Bureau of Mines by GAI Consultants of Monroeville (l,2,3). The GAI model is presented in qualitative terms. This report develops a formal basis for the model and tests a numerical implementation on one of the best-described study areas, Allleqheny County in Pennsylvania.

Jan 1, 1982

By D. G. Foot, J. D. McKay, R. A. Ynchausti

The increasing popularity of column flotation as an efficient and profitable mineral beneficiation technique has resulted in the need to perform a study of basic column operating parameters in order to understand mineral behavior in a column. Variation of column rougher flotation parameters on the Nevada Fish Creek fluorite and Utah Collins manganese ores enabled characterization of four beneficiation zones within a column flotation cell. Although specific mineral behavior in each zone was peculiar to the mineral system involved, particle retention time predominantly affected both manganese and fluorite recoveries in the collection zones of the column while enhancing mineral grades in the cleaning zones. Column parameters such as column length, feed injection location, and tailings recirculation velocity were inherently linked to particle retention time and retention time distribution, both of which affected mineral recovery. Froth depth had a discernible effect on fluorite concentrate grades; as froth depth increased, fluorite grades increased. Wash water additions affected both fluorite and manganese recoveries and fluorite grade. Axial mixing drastically reduced fluorite and manganese recoveries due to short circuiting of some of the feed slurry in the column.

Jan 1, 1988

By R. V. Ramani, R. Bhaskar

Control of respirable dust in mines has been given paramount importance due to the health and safety implications associated with fine dust. Understanding the temporal and spatial behavior of dust has been recognized as essential for increasing the efficiencies of existing control techniques and for developing new control strategies. Mining-related studies in this area are, in general, limited. They are also mostly experimental. Some mathematical and computer analyses have been at-tempted. In this paper, first, a review of the mathematical studies performed in the last three decades in this area is presented. Second, a mathematical model for analyzing dust flow in mines is proposed. The model takes into account a number of factors affecting dust transport. It in¬corporates varying dust generation source strengths and dispersion, deposition, and coagulation of dust in mine airways. Finally, application areas for the model are discussed. A computer program based on the mathematical model has been developed. The program will output the dust concentration in the mine atmosphere as a function of time and distance from the source. The amount of dust deposited on the sides, roof, and floor of the airway is also determined.

Jan 1, 1987

By W. M. Pytel

A simplified two-dimensional model to analyze time-dependent load distribution and surface subsidence associated with longwall mining geometries is described. The model is based on the theory of beams resting on inelastic foundations and includes visco-elastic behavior of immediate floor strata, non-linear behavior of coal pillars, elastic behavior of face supports, and visco-elastic behavior of the overburden strata. The relative importance of the different variables affecting the performance of longwall mining geometries from ground control point of view is also analyzed. The model has been validated for field observations from one Illinois longwall mine.

Jan 1, 1986

By George E. Williamson, Mikiya Higuchi, Michael T. Traylor

Extensive soil conditioning was required to allow Earth Pressure Balance(EPB) tunneling on the South Bay Ocean Outfall tunnel project in San Diego, California, near the Mexican border. This tunnel extends 19,000 feet out under the Pacific Ocean and was mined through soil formations including silts, sands, gravels, cobbles, and boulders. EPB pressures ranged from 3.0 to 7.0 bar, with the maximum pressures required when mining through the highly permeable granular formations.

Jan 1, 1999

Along with kyanite and sillimanite, andalusite forms part of the sillimanite industrial minerals trimorphous alumina-silicate group. Theoretically, andalusite contains about 60% A1203 and 40% Si02, with a Mohs hardness of 7 to 7.5 and a specific gravity of 3.0-3.2. Andalusite generally occurs in the contact metamorphic zones of schists and shales, constituting about 10% of the ground mass ore body. The 5- to 20mm- (0.2- to 0.8-in.-) long crystals are usually liberated through crushing and magnetic/heavy-media separation. Relatively minor occurrences of andalusite are found in Andalusia, Spain (where it was first identified), Portugal, the former Soviet Union, Ghana, South Korea, California and North Carolina. It also occurs in China, France and South Africa. The latter two represent nearly all the andalusite that is exported. Andalusite is an inert refractory raw material that does not require calcining before use. It involves an internal conversion to mullite after heating to 1400° to 1600° C (2552° to 2912° F). At higher temperatures of about 1800° C (3272° F), the mullite converts to corundum and liquid silica.

Jan 1, 1995

By A. Bumanis, K. S. Bawa

INTRODUCTION A rail rapid transit system called the "Metro" system is presently under construction in the Nation&apos;s Capital area. The agency responsible for the design and construction of the Metro system is the Washington Metropolitan Area Transit Authority, an independent tristate organization set up under an Act of Congress and financed by federal, state, and local public funds supplemented by revenue bonds. When completed, the Metro system will comprise nearly 100 route miles. About fifteen percent of this mileage is now under construction, while designs for the-remainder are in progress. The system is scheduled for completion in about eight years at a cost of approximately 3 billion dollars. The Metro system will involve nearly all types of construction generally used for rapid rail transit projects. About half of the mileage will be underground, comprising approximately 16 miles of rock tunnels, 10 miles of earth tunnels, and nearly 21 miles of cut-and-cover construction in earth (see Figure 1.). The remaining 51 miles of the system is planned to be constructed on the surface as at-grade or elevated structures. The system includes 86 passenger stations, 53 of which will be underground structures. Twelve of the underground stations will be large size chambers in rock while other underground stations will be constructed in earth as cut-and-cover structures. Thus, about one-fifth of the system will be designed as underground structures, namely tunnels and stations, in rock. Such designs in rock resulted from the existence of bedrock (schistose gneiss) at reasonable depths generally in the north and northwest

Jan 1, 1997

By Daniel McConvey

Who is the Investor? -Mainly institutional, including resource funds, other mutual funds and pension funds. -Some hedge funds. -Retail investors. -How important is the reserve disclosure to these investors? -Do these investors know the difference between a reserve and a resource?

Jan 1, 2003

By Martin G. Taube, Dwayne A. Lewis

Drainage improvements at O’Hare International Airport, Chicago, IL included the installation of a drainage and storm water system to control the over?ow from nearby Willow Higgins Creek. This involved construction of a weir structure at the creek and the channeling of water from the weir to a newly constructed reservoir via three, 3.7-m(12-ft) diameter, underground storm sewer lines. The sewer lines passed beneath an existing, 2.3-m (90-inch) diameter high-pressure water main, which was to remain in service throughout sewer line installation. The soil composition around the water main ranged from medium stiff clays to silty sands and sandy silts. Triple-fluid jet grouting was used to stabilize the variable soil profile beneath the water main in preparation for tunneling and installation of the sewer lines. The varying soil strata presented a challenge to the project team to establish a constant set of jet grouting parameters throughout the stabilized zone while keeping within the specified unconfined compressive strength range for the stabilized zone of 690 to 1,380 kPa (100 to 200 psi)at 28 days.

Jan 1, 2003

By Mark R. Rybak, James Delmonte, Travis Hartman

The City of Phoenix, Arizona designed a 7.2 km (4.5 mi) long water transmission main from the South Mountain Reservoir to the Ahwatukee Foothills Reservoir to address the growing demand for drinking water in the southeast valley. The pipeline design called for a bored tunnel in a very environmentally sensitive area. The Reach3B contract included an 2.44 m (8 ft) diameter TBM excavated tunnel, 1,847 m(6,060 ft) in length. The geotechnical investigation revealed that the tunnel would likely pass through zones of loose to moderately cemented soils (caliche). The primary tunnel support would consist of rock bolts, circular steel ribs, hard wood lagging, and mine straps. A TBM that could handle the ground conditions and allow for efficient ground support installation was required. This paper describes the construction of a small diameter rock tunnel in challenging ground conditions.

Jan 1, 2003

By T. Chandler, R. Buchan, J. H. Blowes, E. G. Haldeman

The regional geological setting and nature of the serpentinized ultramafic rocks are described. It is postulated that lateritization started in Miocene time. Repeated uplifts led to at least four physiographic cycles and to the development of a mature lateritic soil profile. Complete profiles are subdivided from top to bottom as follows: Zone A - chocolate-brown limonite; Zone B - ochre-brown limonite; Zone C - soft serpentine; Zone D - hard serpentine; Zone E - serpentinized peridotite; Zone F - ultramafic rock. Zones A and F rarely attain ore grade. Canga is conspicuously absent. Rocky ore of Zones D and E amounts to 40%, limonite ore of Zone B to 25% of total ore reserves. Nickeliferous serpentine is the major crystalline phase in Zone C. In this zone and deeper, crystalline quartz occurs, particularly in fracture zones where nickeliferous cryptocrystalline quartz is of ten accompanied by garnierite.

Jan 1, 1979