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By H. Bogart

The Golden Sunlight Underground Mine located near Whitehall, Montana was portalled from the bottom of the existing Golden Sunlight Pit in July 2002. Gold was mined by sublevel stoping in the larger ore zones and longhole back stoping in the narrower ore zones. The stopes varied from 30 feet to 100 feet in width, extended up to 200 feet in height, and were completely unsupported. Underground production averaged 1,500 tons per day with a staff of35 people. The mine operated with a break-even cut-off grade of0.080 ounces per ton.

Jan 1, 2004

By R. D. Archibald

Currently, around 100 million tons of construction materials and aggregates are shipped annually by rail. And recently, producers are looking much more carefully at rail not only to reduce fixed costs through increased volume, but also to eliminate operating headaches, such as increasing community pressures about trucks on the road, noise and dust. Many producers are uncertain as to how to enter the rail shipping business since railroads have historically been reluctant to ship small quantities short distances. This article provides strategies to help producers examine and pursue moving their rock by rail.

Jan 1, 1995

By Ricardo Presnell, Erich U. Petersen, William J. Tafuri, Donald M. Hausen, Douglas N. Halbe

Large (> 100,000 oz.) sediment hosted disseminated gold (SHDG) deposits are often spatially associated with anticlines. Many SHDG deposits are within or closely associated with windows. Windows are erosional manifestations of fold culminations (4-way closed anticlines). Hydrocarbons are often trapped in fold culminations in the Canadian Rockies, and may account for degraded hydrocarbons in many SHDG deposits. In the Eastern Basin and Range Province, Mesozoic anticlines may have been large scale conduits fm gold bearing Mesozoic and Cenozoic hydrothermal fluids which became trapped and/or concentrated at the fold culminations.

Jan 1, 1990

By R. Pazhianur

Many investigators conducted surface force measurements between hydrophobic surfaces in water, and observed attractive force that was substantially stronger than the van der Waals attractive force. The excess force was appropriately referred to as “hydrophobic force”, for which many different theories have been put forth by numerous investigators. In an earlier publication (Yoon and Ravishankar, 1996), it was suggested that the hydrophobic force maybe due to the interaction between the large dipoles created by the surfactants adsorbing on solid surfaces in patches (or domains). In the present work, a mathematical model has been developed to further elaborate the theory.

Jan 1, 2003

The main goal of this paper is to present readers with recommendations for choosing coaxial cables appropriate for mining applications of Time Domain Ref 1 ectometry (TDR) to monitor rock mass movements. Prior to discussing the recommendations, mining applications are illustrated with examples and the operating principle of TDR is discussed briefly. Items that affect the result of the monitoring system performance include the coaxial cable selected, the grouting material used, and the installation procedure.

Jan 1, 1986

By David V. Fitterman, David L. Campbell

We've used direct current resistivity (DC), electromagnetic (EM), induced polarization (IP), and ground-penetrating radar (GPR) geoelectrical methods to study mine dumps. The results reflect lithology, pore water saturation, and dissolved solids in the pore water. If the pore water has a pH less than 5, conductivity maps can indicate acid generating potential. IP measurements can help distinguish mineralogy in mine dumps, especially concentrations of sulfide minerals. EM and DC can help locate acidic/high TDS groundwater associated with mine dumps. GPR methods failed at the sites we studied in the West. Our own conclusions are augmented by those from the recent literature.

Jan 1, 2000

By F. Vallianatos

The main objective of the present investigation is to demonstrate the potential of ERT (Electrical Resistivity Tomography) and HVSR (Horizontal to Vertical Spectral Ratio) methods as geophysical tools for the monitoring of subsurface cavities. The survey sites are located in Akrotirion Peninsula, almost 7 km east of Hania town in Crete Island, Greece. At this site, the surface expression of a known cavity with a diameter of about 25 m is visible. The true geometrical characteristics of the cavity were unknown since there are no boreholes in the area. The focus of this survey was primarily of a qualitative nature and the objective was to determine if ERT and HVSR could be used to identify and map near surface cavities (less than 30 meter in depth) in a limestones kartsic area such as Akrotirion Peninsula. A 2D/3D model of the resistivity distribution is given for the area under investigation. Furthermore, analysis of microtremors data provides a profile of the seismic response of the tectono-karstic voids.

Jan 1, 2006

By William A. Vogely, Robert T. Deacon, Walter J. Mead

Oil and gas together are the most important energy sources consumed in the United States. In 1983, 67% of total energy consumption was represented by these two resources (43% was oil and 25% natural gas), while coal accounted for only 23% of U.S. energy use. All other sources (hydroelectric, nuclear, geothermal, wood and other waste products) accounted for only 10% (U.S. Department of Energy, 1983, p. 1). In this chapter we address the issue of regulation in the oil and natural gas sectors of the U.S. energy industry. In addition, we analyze the cartel characteristics of the Organization of Petroleum Exporting Countries (OPEC). If OPEC is an effective cartel, then U.S. oil as well as substitute energy prices, production, and consumption will be affected by cartel action. Further, as the nation learned in the 1970s, major changes in oil prices produced major disturbances in other sectors of the U.S. and world economies. Consequently, it is important to determine whether the roughly ten-fold increase in nominal prices that occurred in the 1970s was the result of cartel action, the result of normal economic forces adjusting to the fact that the world was running out of cheap oil, or some combination of the two. Furthermore, the presence of OPEC- associated oil price increases is related to regulations that were imposed on the energy sector during the decade of the 70s. THE RATIONALE FOR GOVERNMENT INTERVENTION Economists have traditionally judged the state of an economy to be efficient if it is impossible to improve the welfare of any one member of society without harming someone else. Any economy that satisfies this condition is said to be Pareto efficient, after the Italian economist Vilfredo Pareto who first gave rigorous attention to such questions (see Chapter 4.10). It is easy to see why an economy that fails to satisfy this condition could not be efficient; by definition, it would be possible to alter the allocation of resources in a way that improves everyone's welfare.' Much of the appeal of this weak efficiency criterion is that it avoids comparisons of levels of well being among different individuals. The cost of such generality, however, is that in any given economic system a wide array of different Pareto efficient states will typically be attainable. In the simple Robinson Cursoe economy of the undergraduate textbook, for example, efficiency could just as easily be attained in the case where most of the island's resources are owned by Friday as in the case where they are under Crusoe's control. However, the distribution of welfare among the two inhabitants would obviously be quite different in the two situations. Such equity issues cannot be settled on objective or scientific grounds. To decide which distribution of welfare is socially "best" an explicit value judgment is needed. It is useful to keep in mind the preceding distinction between efficiency and equity issues when analyzing the role of government in a market economy. Decentralized market processes will not necessarily result in a distribution of welfare that society considers just. For this reason a potential role for government lies in the redistribution of income among individuals. In some circumstances, however, market pro-

Jan 1, 1985

By Mohamed Gamal, Bill Zietlow

"In oil fields that have been depleted with conventional surface oil wells but still contain significant reserves, an extraction alternative that has been constructed recently consists of a drilling gallery below the oil-bearing formation at the bottom of a 1,200-ft deep shaft where upward sloping wells are being drilled to allow oil collection by gravity. The gallery is 92-ft diameter with a flat ceiling supported by rock bolts and shotcrete structurally connected to the shaft liner, which doubles as a large tension support element. A special excavation sequence was implemented for the gallery to maximize arching in the stress above the large diameter gallery. The gallery was located in competent sandstone, constructed with sequential excavation methods, and designed with a 3D finite element model. Special consideration was given to optimizing the gallery location to take advantage of the geology for construction and support while giving good positioning to the well drilling equipment. BACKGROUND Brierley Associates was contracted to provide both design and construction management services for an approximately 1,165-ft deep, 18-ft excavated diameter vertical shaft that opens to a 92-ft diameter flat roof gallery. The geotechnical data for the site was based on information available from literature and from data obtained during core drilling and from in-situ testing in a 1250-ft deep borehole. Wire line coring was conducted using a HQ, 10-ft long core barrel with a mud-rotary drilling method through sedimentary bedrock. The geometry of the shaft and the bottom gallery is shown in Figure 1(a). GEOLOGIC SETTING AND STRUCTURAL GEOLOGY The stratigraphy at the site includes a series of interbedded marine limestone, shale, claystone, siltstone, sandstone, and chert units. Limestone and shale are the predominant lithologies in the upper approximately 675 ft, while the lower portion contains five distinct sandstone units and more abundant shale, claystone, siltstone, and coal than the upper zone. A cherty sandstone at a depth of 1,130 below ground surface (bgs) was encountered. At a depth of about 1,000 ft to 1,116 ft bgs, a non-marine sandstone unit was encountered. This sandstone is the hydrocarbon bearing layer. Joints and fractures observed in the limestone had dips ranging from 0 to 90 deg. from horizontal with joint and fracture surfaces that ranged from planar to irregular and smooth to rough. Several, near vertical shear planes with slickensides were observed with surfaces that were generally smooth and planar. RQD values for the limestone ranged from 0 to 100 percent but in general were good to excellent."

Jan 1, 2016

By H. C. Verakis

Permanent ventilation controls such as stoppings, overcasts, and undercasts for use in coal mines are required to meet MSHA’s safety standards for fire endurance and flexural strength. Due to technological advances in materials and their design for use as ventilation controls, an engineering program was established to evaluate newer or “nontraditional” ventilation controls. The program is intended to assist manufacturers, enforcement personnel and mine operators in determining if “nontraditional” ventilation controls, for example plastic membrane construction and lightweight block, meet the prescribed safety standards. The program is presented with a description of required tests and examples of products evaluated.

Jan 1, 2003

By N. Finkelstein, D. A. Hinckfuss

The large and compact but simple Bougainville Copper Limited flotation circuit has been in operation for 3-1/2 years. Discussion of problem areas encountered since start-up and remedies that have been implemented or proposed, form the main basis of this paper. Full cur- rent operational data is also provided.

Jan 1, 1976

By T. R. von Ow

The method of powering mills such as AG, SAG and Ball has a long and technically interesting history. It can be said that almost every decade in the last half century had its own trend. The trends were dominated by the market demand, the advanced process development and requirement of the mechanical and the electrical technology but mostly by the price of the applied technology. The increasing size of the ring geared mills in the last years requires more awareness on the drive train solution. Special attention must be paid to the mechanics and the requirements of the power grid. Operational challenges such as soft starting and controlled operation as well as the protection of the equipment have gained importance. Frequency converter drive solutions dedicated to single or dual pinion ring-geared mills offer significant advantages over conventional drives due to their application specific features and controls. Solutions with low speed motors as well as high speed motors cover all possible configurations available for ring geared mills.

Jan 1, 2010

By Petr Salak, Adrian St. John, Angelos Gakis

"INTRODUCTIONCrossrail will provide London and the South East of England with a world class, high-capacity railway to ease congestion on London’s public transport system and enable better access between business, residential and entertainment districts. At the heart of this £14.8bn scheme lies Farringdon Station, which will form a major interchange between Crossrail, Thameslink and London Underground. The £400m Farringdon Crossrail station was awarded to a joint venture of BAM Ferrovial Kier (BFK) in 2011, and comprises two ticket halls, two platform tunnels and a multitude of connecting tunnels all constructed using open face sprayed concrete linings (SCL). BFK appointed Dr. Sauer & Partners (DSP) as their specialist SCL designer. As the main contractor for both C300/C410, the Western Running Tunnels and Station Caverns, and also for C435 Farringdon Station, BFK were in a unique position to develop strategies to reduce cost, time and risk for the Client. One such innovation involved the continuation of the TBM drives for the running tunnels right through the length of the new Farringdon platform caverns. This created large diameter precast concrete pilot tunnels for the subsequent platform enlargement using SCL. The benefits of such an approach are described in detail by St.John et al 2015. BFK also introduced another alternative strategy to reduce cost, time and risk, by proposing to abandon the TBMs in the ground (“Turn & Bury”) permanently rather than recovering them through the ticket hall shafts. This de-risked the programme, enabling critical ticket hall construction to proceed unhindered. However, one consequence of this revised strategy was an area of increased underground congestion, with two SCL tunnels (RTE2 and ES2) and a bored tunnel (complete with abandoned TBM) in close proximity to a ticket hall excavation (see Figure 1) and a sensitive, listed railway structure. Faced with this complex geometry, and combined with challenging geotechnical conditions (Gakis et al 2015), the team chose to install enhanced monitoring to study the behavior of tunnel RTE2 and provide additional assurance that the tunnels were performing as predicted. Applying advanced 3D numerical modelling and taking into account the residual tensile strength of the SCL helped avoid unnecessary reinforcement installation in primary lining and/or early installation of a secondary lining in RTE2 prior to ES2 construction."

Jan 1, 2016

By John W. White

Anthracite mine refuse, or culm dump material as it is sometimes called, is the waste material resulting from the sizing and cleaning of run-of-mine deep and strip-mined anthracite coal. It may also contain mine rock, carbonaceous shale, pyrite, and other debris from mining operations. This material is generally stored in piles or banks, some of which are over 100 years old. Many of the older banks contain a considerable amount of good coal, particularly in the finer size ranges, since these sizes did not have any particular economic value in the early days of anthracite mining. Today, the refuse material from a cleaning operation must be piled in an orderly fashion and in such a way as to minimize the tendency to ignite. There are well over 400 of these banks in the anthracite region containing over 1100 million tons of refuse located in the north-eastern part of Pennsylvania. The banks range in size from a few thousand tons of material up to as much as 13 million tons. Most of

Jan 1, 1972

By Fred N. Kissell

INTRODUCTION During the last few years, several new ventilation developments have attracted the interest of mining engi¬neers. Some of these developments are applicable pri¬marily to hard-rock mining, while others are more applicable to coal mining. STOPPINGS Parachute Stopping The parachute stopping is a new type of quick-erect stopping that is intended for temporary use in hard-rock mines (Kissell, Thimons, and Vinson, 1975). As shown in Fig. 1, the stopping is shaped very much like an ordinary parachute, with a canopy of impermeable fabric that is sewn to regularly spaced straps running to a common point. To erect the stopping, the straps are attached to a fixed anchor point such as a roof bolt, and the edge of the canopy is lifted into the moving air¬stream. The airstream pops the parachute canopy into place, and the differential air pressure across the stop¬ping holds it in place, forcing the fabric against the walls, roof, and floor of the mine opening. The principal advantage of the parachute stopping is that it requires only a few minutes to install, making it a great time-saver for emergency use or for day-to¬day changes in ventilation during the production cycle. However, the parachute stopping does require some minimum air velocity to lift it and some minimum differential pressure to hold it in place. For a fabric weighing 0.27 kg/ m2 (8.0 oz per sq yd), the minimum air velocity is about 0.5 m/s (100 fpm), and the mini¬mum differential pressure is about 0.05 kPa [0.2 in. water gage (WG) ]. There is always some air leakage around the stop¬ping, mainly depending upon the extent to which pipes or other obstructions encumber the airway and prevent good sealing. Leakage of a few cubic meters per second (a few thousand cubic feet per minute) can be expected, unless foam is used to improve the seal at the edges of the canopy. Quick-Fix Blowout Stopping The quick-fix blowout stopping is a variation of the parachute stopping (Thimons and Kissell, 1976), and it is used in the proximity of blasting operations. This type of stopping is designed to be blown out easily by the blast forces, and it may be reinstalled quickly and easily. The long high-strength straps of the parachute stopping are replaced by groups of short straps that tear easily. These straps are attached at six equally spaced locations around the perimeter of the canopy. To erect the stopping, one strap of each of the six groups is fastened to the mine wall, roof, and floor by using spads, by setting pins with a powder-actuated gun, or by tying the straps to some firm anchor point. Once the straps have been attached, the differential air pressure across the stopping, which must be at least 0.025 kPa (0.1 in. WG), forces the stopping perimeter against the mine walls, thus creating the air seal. It is the self-sealing feature of this stopping that makes it a significant time-saver. Only a few attachment points are needed; in many cases, four attachment points are sufficient, since the stopping naturally tends to form a seal with the airway surfaces. When nearby produc¬tion blasting exerts excessive forces on the stopping, one or more of the straps tears away from its attachment point, protecting the stronger canopy from damage. Damage-Resistant Brattice The damage-resistant brattice is a stopping that is designed for use in mines such as salt and limestone mines where the differential pressures are low and the roof is relatively flat. As shown in Fig. 2, the damage-resistant brattice consists of a series of brattice panels that are hung vertically and joined by Velcro® connections. When the brattice is subjected to strong blast forces, the Velcro® connection peels apart and allows the panels to open without incurring damage. The Velcro® connections can be resealed by hand within a matter of minutes. Such damage-resistant brattices have withstood the blast effects of 318 kg (700 lb) of ammonium nitrate-fuel oil (ANFO) explosive detonated as close as 91 m (300 ft) from the brattice. Ordinary brattice cloth is used for the panels, with a 51-mm (2-in.) wide strip of Velcro® hooks sewn along one edge of the length, and a 51-mm (2-in.) wide strip of Velcro® pile sewn along the other edge. Both the hooks and the pile are sewn onto the same side of the brattice cloth. The resulting Velcro® seal formed be¬tween adjacent panels is perpendicular to the brattice itself, and the leading edge of the seal can be directed either toward or away from the blast forces; the brattice works equally well in either case. To hang the brattice, panels of brattice cloth about 0.9 m (3 ft) longer than the height of the airway are cut from a 1.8-m (6-ft) wide roll. The additional 0.9 m (3 ft) of brattice cloth allows 0.3 m (1 ft) for attachment to the roof by means of a board, with 0.6 m (2 ft) for forming a good air seal at the floor. Each brattice panel is wrapped once or twice around a 51 X 102 mm (2 X 4 in.) or 25 X 76 mm (1 X 3 in.) mounting board that is 254 to 305 mm (10 to 12 in.) shorter than the width of the panel. For convenience in

Jan 1, 1982

By Charles H. Jacoby

In 1960 the management of International Salt Company made the decision that all waste material from the Watkins Glen plant would be stored in underground salt cavities. The cavities which they contemplated using had been depleted of salt to a point where continued operation would have impaired their structural stability. Originally, the waste to be disposed of included vacuum pan bleeds, cinders, contaminated salt and sewage. It was proposed that this material, in a slurry form, was to be injected into the salt cavity through one of the abandoned wells. Brine, displaced from the cavity, was to be recovered from an adjacent well and subsequently injected into the Cherry Valley limestone, This Cherry Valley limestone which underlies a large portion of north central New York contains a connate water with high concentrations of ammonia, hydrogen sulphide and the chlorides of calcium, magnesium and sodium. A number of questions were immediately raised on various aspects of the technical feasibility of the project. Of major concern was the buildup of insolubles adjacent to the bore of the injection well. Another pertinent question was the carryover in the displaced liquor of finely-divided, mechanically-suspended particles. Criticism was leveled at the inclusion of sewage. Engineering studies were started by the company's Mineral & Mines Development Department and on April 3, 1961 a preliminary feasibility report was issued.

Jan 1, 1973

By Richard L. Bullock

At the beginning of the previous chapter, variation in the types of room-and-pillar stopes were briefly identified so that the reader could begin to understand the extensive application of this mining system. These same variations will be reviewed and elaborated upon in this chapter while discussing the methods by which the material is extracted. FULL-FACE SLICING BY DRILLING AND BLASTING When the entire mineralized thickness is taken in one pass of mining, it is known as full-face slicing. There is no mineral of economic value intentionally left either in the floor or the back. Theoretically, there is no limit as to how high the face could be in a single pass. But there are practical limitations to equipment size, pillar stability, and control of local loose slabs on the face, roof, and pillars that dictate current practices. The range of face height of the 15 typical room- and-pillar mines covered in Table 8 (Sec. 1, Subsec. 7) from the Dravo report, 1974 was 1.7 m (5.5 ft) to 9.8 m (32.1 ft), the average being 5.2 m (17.1 ft). In the Gaspe copper mine, Murduchville, Que., the drill jumbos were constructed with an extendable tower for full-face mining up to 15.2 m (49.9 ft) if necessary. However, a more common practice at that mine is to take the ore in multiple slices (Hall, 1959). In many metal mines the normal practice when starting stoping is to drive a single development drift into the ore zone a distance that will allow at least four or five rooms to be opened on each side of the initial drift. Since this opening will probably serve as the main haulage drift, it should be kept as straight and as level as possible. As to the other criteria for the stope developments, it might be well at this point for the mine planner to review the remarks presented earlier (Sec. 1, Subsec. 7) on drifts, entries, and crosscuts for production. After the initial drift is driven, it should be slabbed to the full room width if it is not that wide already. Next, the future pillars should be marked on the ribs and the rooms driven between them. If the ore extends beyond the length of the initial drift and is to be mined in the normal sequence of mining, care should be taken in a random room-and-pillar system to see that the extension of the initial roadway remains straight. If pillar "spotting" is left to the shift foreman or to the miners, they probably will not realize the importance of maintaining a uniform pillar line next to the roadway, and of keeping the line straight. Invariably, a pillar will end up in the middle of the future drift extension resulting in a "dogleg" in a possible main haul- age road. While this error is not catastrophic, too much weaving in and out of pillars will certainly slow down future production haulage and needlessly increase costs. Face or Breast Drilling and Blasting Practices To drill and blast the initial advances into the rock, usually some form of cut pattern must be used. In room-and-pillar mining, when a pattern is drilled in a face and that face is the only exposed surface to which all of the rock must be broken, the pattern is known as a "face round" or "swing." The face to which the rock must be broken is referred to as a "free face." Thus the most common way to advance a room into virgin rock with only one free face is by drilling swings. If, after breaking around a pillar, taking down back, or taking up bottom, there is a second (or third) face exposed, a group of holes drilled nearly parallel to a free face and breaking to it is known as a "slab round" or "slabbing." In some mining districts it is also known as "slashing." Obviously, because two faces exposed offer less resistance to fragmentation than a single face, slabbing requires less drilling and fewer explosives than required to break the same tonnage with the same degree of fragmentation with swings. Therefore, it behooves the driller (or supervisor) to plan the combination of

Jan 1, 1982

By Abdullah Arik

The resource classification methodologies have always been a topic of research and debate. There are both traditional and Geostatistical methods used in practice. Because of the uniqueness of each ore deposit, it seems almost impossible to have a single industry-accepted norm for resource classification. Therefore, some practitioners have adapted the methodologies to suit the deposits they are working on, but many simply use the methods they are comfortable with. Another reason for the existence of varying classification methodologies is the lack of an easy and established way to measure the confidence in the estimates. Therefore, their classification becomes a subject of debate. In this paper, a new approach is offered to classify the resources using a "Resource Classification Index." The approach using this index takes into account the local variation, the spatial data configuration around the block being estimated, as well as the traditional distance measures. A case study for a gold deposit is presented to demonstrate how this new index can be used to classify the resources. The results from this approach are compared to those from two popular classification methodologies.

Jan 1, 2002

By F. M. Doyle, P. E. Richardson, E. Peters

A number of studies have attempted to correlate the semiconducting properties of mineral sulfides with their chemical reactivity. Frequently such studies are conducted on polished or abraded electrodes. Defects produced by abrasion may mask the influence of the semiconducting properties of electrodes, e.g., by pinning the Fermi level at the surface or by reducing the lifetimes of photogenerated charge carriers. It is shown that pyrite and galena electrodes have photocurrents that are extremely sensitive to abrasion of the electrodes. On freshly fractured galena surfaces, the space charge layer is readily polarized. Wet-abrasion is shown to produce a relatively thick ptype layer on galena electrodes and this p-type layer has a pronounced effect on the photoresponse. On freshly fractured pyrite surfaces, the Fermi level at the surface is pinned by a surface state. Wet-polishing reduces the magnitude of the photocurrent by over an order of magnitude.

Jan 1, 1993

By H. F. Ghezzi

The indirect method of drying coal fines is applied to filter cakes which ordinarily contain 22 to 30% moisture and are not readily transportable. The "Thermal Dryer", which operates on the mass transfer principle, has found wide use in coal preparation plants. The thermal dryer is penalized in operation by the necessity of adding coarse coal to the wet fines before entering the dryer body in order to produce a permeable bed, and thus enable hot gases to uniformly contact the wet mass. The ratio of coarse coal to fines varies from 2:1 to as much as 4:1, depending on the average particle size, moisture, and ash content of the fines.

Jan 1, 1985