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By M. J. Shulman

The exploration geologist is frequently confronted with the problem of allocating his resources, i.e., exploration effort, among various areas. Although geologic, financial, and logistic considerations influence the allocations, no objective criterion is usually given that determines the optimal allocation. Maximizing the expected gain in information, subject to the constraint of a limited exploration budget, is used as the objective criterion to allocate airborne reconnaissance effort. The information function, I(x), quantifies the expected gain in information, where x is the scale of exploration. To calculate the information function, the following probabilities are required: the probability that an area contains a deposit; the probability that an anomaly is produced by the target; and the probability that an anomaly is produced by a barren area (false signal). Alternatively, the barren areas can be replaced by other targets. To illustrate the allocation method, the optimal number of line kilometers, i.e., the optimal line spacing per area, is determined for an aeromagnetic survey for iron in Egypt.

Jan 1, 1987

By J. Craig Green

Companies mining for coal, oil shale, and minerals in the western US must often complete extensive geotechnical studies to satisfy federal and state regulations. The modern mining process is further complicated by the legal problems and liabilities associated with mineral rights and land leasing. Yet the study of water rights-unique to the West is often incomplete or ignored until the latter stages of mine planning. Water rights in the West are not adequately understood by many mining companies and their geotechnical consultants. Some firms, headquartered outside the western US, have not had to contend with the water supply problems of a semi-arid region. Water problems encountered by eastern mining companies, for example, are primarily water quality, drainage, and flood control. Even when water quantity is a problem in these areas, ownership and/or use of it is governed by entirely different legal and administrative concepts than in the West. Both legal and engineering issues have to be considered when studying western water rights. Legal issues, such as existence and title, must be addressed to insure that a particular water right is properly established and maintained. The exercise of a water right, however, often requires engineering analyses that focus on preventing injury to the properly established water rights of others.

Jan 8, 1981

By William Cass, Ellen Caftel Turcotte

The Elliot Lake Centre was established in 1965 as an independent Centre for Continuing Education offering a variety of adult education services. In 1976 all retraining and community college type activities were transferred to the Sault College of Applied Arts and Technology which had opened a branch campus in Elliot Lake. Upon the completion of this transfer, the Elliot Lake Centre was then contracted in 1977 by the Canada Centre for Mineral and Energy Technology to study the feasibility of establishing a research and information institute dealing with various health and safety concerns of the uranium worker. By late 1980, a federal charter was granted for the establishment of the Canadian Institute for Radiation Safety, made possible through the cooperative efforts of the Governments of Canada and Ontario, the Ontario uranium mining and refining companies, and the Elliot Lake Centre. On 1 April 1981 the Institute officially began operations. PROGRAM DEVELOPMENT AND COORDINATION In May 1978 the Elliot Lake Centre initiated a voluntary sputum cytology program for uranium workers. This program was financed by the Ontario uranium mining companies: Agnew Lake Mines Limited near Sudbury; Madawaska Mines Limited in Bancroft, and Denison Mines Limited and Rio Algom Limited in Elliot Lake. In 1981 additional funding was granted by Eldorado Nuclear Limited for a small group of employees at the company's uranium refinery in Port Hope, Ontario. Initially in 1978, program participants were accepted according to length of employment, radiation exposure levels (calculated in working level months) and/or smoking history. These restrictions were abolished within a few months and all uranium workers were encouraged to participate. From 1978 to 1979 the sputum cytology program was medically directed by personnel from the Montreal Cancer Institute. Until 1979 all data maintenance for the program was performed manually, however the effort required to sustain the system increased significantly as the number of participants grew. In September 1979 the Division of Thoracic Surgery at the Toronto General Hospital, under the direction of Dr. F.G. Pearson, submitted a proposal to the Elliot Lake Centre to develop a data processing system to help coordinate the surveillance program. In October 1979, Dr. Pearson became the new Project Director. Director of the Cytology Program is Dr. D.W. Thompson of the University of Toronto who is responsible for all cytologic analyses. Developmental work to establish the new surveillance system was initiated in January 1980 and became fully operational at the beginning of March 1981. The following sections describe the Elliot Lake operations of the sputum cytology program now conducted by the Canadian Institute for Radiation Safety. PROGRAM PARTICIPATION As of 1 September 1981 the sputum cytology program has 518 participants enrolled. Eligibility is restricted only to a willingness to participate and the ability of an individual to produce adequate sputum samples. Each participant registers for the program at the Institute and is given personal instruction on methods of sputum collection. The majority of the participants in this program are employed by the uranium mining industry; some work for firms which are contracted by the larger companies. Many participants are either retired from the work force or receive disability pensions or workmen's compensation benefits. Other participants have been employed in the uranium mining industry and have since gone on to other employment; some work for various federal and provincial governmental agencies concerned with the mining industry. Some participants are referred to the program by their family physicians because of smoking histories and/or various respiratory conditions. A small number of these individuals have never been involved in the mining industry at all. A chart describing program participation by employment is found in Appendix 1. PROGRAM REGISTRATION In the Elliot Lake area, persons interested in registering in the program are required to go directly to the Sputum Cytology office located at the Canadian Institute for Radiation Safety. Each individual is interviewed personally by the Program Officer. For the employees of Agnew Lake Mines, Madawaska Mines and the Port Hope refinery of Eldorado Nuclear Limited, registration is possible during the Program Officer's semi-annual on-sitevisits. Participants are assigned, in chronological order, "program numbers" for easier identification. File labels are color-coded according to place of residence or, in some instances, place of employment. Each file is stamped with the date each sample bottle is distributed. A file contains: all original test results, a completed registration

Jan 1, 1981

By Harry H. Posey, John Woodling, Miriam L. Renkin

Natural acid drainage is generated from pyritic rock underlying 17 percent of the upper Alamosa River basin. About one-third of these acid producing rocks have nil carbonate buffering capacity; there the streams carry significant acid plus dissolved Al, Cu, Fe, and Zn. In part of the basin, aquatic life is limited by the natural acid drainage. In the four miles where the Alamosa flows through pyritic rock the river grows toxic to trout. Inhospitable conditions continue downstream for at least another four miles. The waters become refreshed, naturally, through metal dilution, metal oxide and hydroxide precipitation, and acid neutralization. Water quality fluctuates in seasonal cycles. Dissolved metals and acid, which are generated year-round by weathering, are stored over winter in the unsaturated zone in the retained water and in soluble metal- sulfate minerals that form by evaporation of acid-metal waters. Seasonal discharge variations cause metal concentrations and pH to shift in the trunk stream; the acid drainage source streams, however, shift only slightly by season. In early spring, metal concentrations and metal loads increase as metals and acid are flushed from the unsaturated zones by melting snow. Peak metal loads occur at this time, and precede peak flow by up to two months. Other metal load peaks occur during peak flow and monsoon flow, even though metal concentrations are diluted at that time by precipitation. In late spring and thereafter, discharge of neutral pH water wanes, so trunk stream pH falls and metal concentrations return to previous high levels. Metal concentrations appear to be low from November through January when dilution from precipitation is lowest, but rise in February to near peak yearly concentrations. In years with high monsoonal flows, metal-laden waters apparently flush from the unsaturated zone and metal concentrations remain low from about October through January. In years with low monsoonal flows, however, metal concentrations in October and November at least are higher.

Jan 1, 2000

By S. K. Kawatra, A. K. Bakshi

Mineral suspensions in water show Newtonian flow properties at low percent solids. However, this changes to a non-Newtonian regime as the pet-cent solids increases. For Newtonian fluids, viscosity is independent of shear rate, hut, for non-Newtonian fluids, viscosity varies with shear rate. Therefore, if the slurry is non-Newtonian, attempting to measure the viscosity at a shear rate different from the shear rate experienced by the fluid within the process is futile. This is especially true for a hydrocyclone, where the rate of shear is different at different points within the hydrocyclone. In this case, it is very important to determine the flow type of the suspension before attempting to establish any correlation between the viscosity and the process efficiency. A new technique to distinguish such changes inflow type was developed. This involves two viscometers: a coaxial cylinder-type viscometer that measures apparent viscosity at low shear rates and a vibrating sphere-type viscometer that measures the apparent viscosity at high shear rates. For each of these instruments, special precautions were taken to allow, for the measurement of the viscosity of rapidly settling mineral suspensions. Because the vibrating sphere viscometer is operated at a much higher shear rate than the rotating viscometer, the two instruments together could determine the shear-rate dependency of the viscosity. Ground silica (80% passing 65 µm) in water was used to prepare slurries at concentrations ranging from 10% to 70% (by weight) solids. The viscosity of each slurry sample was measured simultaneously by both viscometers, and the results were compared. With this technique, it was found that all of the silica-slurry samples tested were in the Newtonian flow regime for up to 70% (by weight) solids. Methocel and Cellosize polymer solutions showed clear non-Newtonian behavior using this technique. This confirmed that non-Newtonian behavior of the silica slurries, if present, would have been detected by this arrangement.

Jan 1, 1997

By Patrick Corser, Mitch Usibelli

Introduction Coal mining in Alaska's interior, specifically in the Healy area, began as early as 1918 with the construction of the Alaska Railroad. Mining was originally limited to underground operations but has expanded to entirely surface operations. In 1943, the Usibelli Coal Mine was formed and started developing Alaska's first surface mine east of Suntrana (Usibelli Coal Miner, 1984). Production from the local coal deposits has steadily increased and, in 1978, surface mining of Poker Flats was initiated (Fig. 1). Currently, a 25-m3 (33-cu yd) walking dragline strips two coal seams, using an extended bench on the second pass. In addition, a fleet of trucks and shovels are used for coal removal and some limited overburden stripping. In 1984, a contract was signed between Usibelli Coal Mine and Sun Eel Shipping Co. in 1984. Since then, production has nearly doubled to more than 1.3 Mt/a (1.5 million stpy). This article will discuss geotechnical constraints on mining within the steeply dipping coal deposits that exist within the Poker Flats mining area. Specifically, the article will describe how the mining operation retriggered an historic landslide on the No. 5 coal seam (Fig. 2). And the article tells how a mine plan was developed that allowed the coal to be safely removed without inducing additional movement. Regional geology The coal-bearing group in the Nenana coal field is of Tertiary Age. It is overlain in some areas by several thousand feet of Tertiary gravels - the Nenana Gravels. In areas mined by surface methods, the Nenana Gravels have been eroded off, and up to 30 m (100 ft) of quaternary outwash gravels overlay the coal-bearing formations. The coal-bearing group is divided into five formations: Healy Creek, Sanctuary, Suntrana, Lignite, and Grubstake (Wahrhaftig, 1969). Lignite Creek lies on the north limb of a west plunging anticline. This has brought the Suntrana coal-hearing formations near enough to the surface to allow surface mining. Mining is presently in progress on the south side of Lignite Creek in the Poker Flats area. The coal-bearing formation is cut off to the south by a fault having perhaps several thousand feet of vertical displacement, with the upthrust side to the north. South of this fault, Nenana Gravels are exposed on the surface. The Suntrana Formation contain the minable reserves at Poker Flats. This formation is a repeated sequence of poorly consolidated pebbly sandstone near the bottom, grading through a silty fine sandstone to a footwall clay unit immediately below a coal seam cap. The footwall clays are high plasticity clays to silty clays. It has been reported that they contain 30% to 50% montmorillonite (Usibelli Coal Mine Inc., 1982). There are six coal seams in the Suntrana Formation, No. I (the lower seam) through No. 6. Only the top four seams are currently exposed. No. 3, No. 4, and No. 6 seams are the only mined seams. The No. 5 seam is very thin or not present. Portions of the undisturbed Suntrana Formation are overlain by up to 15 m (50 ft) of Quaternary outwash gravels or recent landslide rubble. The surface is overlain by a very thin layer of muskeg and isolated areas of permafrost. In many areas, the outwash gravels are found immediately below the surface muskeg. Numerous landslides have been documented along the north facing slopes of Lignite Creek (US Geological Survey, 1970, and Wahrhaftig, 1958). These appear to be surficial solifluction or skin flow types of landslides. In addition, deep-seated structurally controlled slides are also evident on both the north and south sides of Lignite Creek. Structural features Premining aerial photographs (Fig. 3) of the Lignite Creek slopes in the Poker Flats area indicate substantial evidence of deep-seated landsliding. The landslides noted in Fig. 3 are both inside and outside of the current mining area. Surface mapping and geologic exploration indicate that the coal seams are dipping out of the slopes within the noted slide areas. It is suspected that, historically, these landslides were triggered by undercutting of the toe of the slopes by Lignite Creek. And sliding it thought to have taken place on one or more of the clay beds underlying the coal seams (Golder, 1985). The slide areas are characterized by semicircular head scarps and slumped topography. Based on the premining photographs, these slides do not appear to have been recently active. However, they are expected to be in a state of only marginal stability. Extensive coal exploration indicates that the primary structural feature within the

Jan 1, 1989

By L. O. Bond

High costs--and high risks--are normal in coal exploration and mine development. But risks and ultimate costs are minimized by foreknowledge of prospective coal seams and adjacent formations. Extensive drill hole programs are often used to obtain needed information. Cores and cuttings from these holes are used to determine coal location, thickness, and quality; they are also used to study physical and geological characteristics of surrounding beds. Valuable as these core and cuttings studies are, their effectiveness is often diminished by loss of recovery or by incomplete analysis. Needed is an effective and economical method for augmenting these studies. Well logs provide information of the type needed for efficient cool prospecting. Furthermore, obtaining these logs in drill holes, and evaluating the data they provide, is both fast and economical. To investigate the usefulness of well logging methods in coal explorations, the authors worked with Mr. Jon Jenkins of Truax Truer Coal Company. Logs were run in a number of drill holes in various areas of the Illinois Basin; these areas provided variety both in coal quality and geologic conditions. The data were studied extensively using computer methods similar to those now used in the evaluation of oil and gas wells. (2, 3) This study was used to produce a computer-generated analysis designed especially for mining problems.

Jan 1, 1969

By Peter A. Gillett, Ian S. Clelland, J. G. S. Hynd

Today mine shaft and slope contracts include a greater amount of ancillary work such as level and pump stations, loading pockets, rotary and side dumps and connecting raises. This ancillary work requires the application of a number of construction methods often for short periods and often at short notice if the contractor is to maintain a profitable operation. In the next decade, the number of shafts that will be sunk by a boring method will outnumber those sunk by traditional methods. This will be particularly true of the deeper shafts where water problems are minimal. The increase of bored shaft work will not decrease the work completed by the shaft sinking contractor but it will change it. A greater emphasis will be placed on the speed of construction of station and other ancillary work. To meet this challenge the contractor requires full information on the ancillary work as well as the shaft work at an early date, preferably pre-bid. The two examples discussed in this paper illustrate the importance of early information. The two main factors of shaft ancillary work construction are sequence and ground support. This paper describes two examples completed recently by The Cementation Company of America Incorporated in Arizona. The first described is a Rotary Dump-Ore Pocket-Ore Pass complex and the second described is the excavation of the Main Station Level in a 2 Station-Loading Pocket-Ore Pass complex. CONSTRUCTION OF ROTARY DUMP, ORE POCKET AND PASS Introductory

Jan 1, 1976

By Gerald J. J. Aleva

Lateritization is a surface and near-surface process enhanced by a humid and warm climate and by good drainage. It closely follows the development of the regional landscape. The cyclic landscape development on the Guiana Shield is accompanied by a progressively thicker and more evolved laterite mantle the older, and hence in most instances the higher the planation level. The known, economically interesting bauxite and aluminous laterite eposits of the Shield are restricted to the remnants of the oldest of the Cainozoic planation levels (level I1 and 111).

Jan 1, 1984

By J. W. Hawkins

Understanding aquifer properties in surface mine backfill is essential for managing the groundwater flow system as well as controlling the formation and discharge of acid urine drainage. Slug tests (injection and withdrawal) performed on wells in mine spoil may yield two distinctly different response characteristics. One type of response is indicative of a porous media system. The second type of response indicates the presence of a pseudokarst system. The presence of voids or conduits in the backfill is indicated by an almost instantaneous partial recovery of the water level displacement. This rapid recovery is turbulent flow and cannot be analyzed by conventional (Darcian) methods. The turbulent flow may cause the calculated hydraulic conductivity to be less than the actual values. The slug dissipation surface area created by the voids contiguous to the test well add to the known dissipation surface area of the screened interval. This can cause the calculated hydraulic conductivity to be greater than the actual hydraulic conductivity or the aquifer to appear more permeable. Whenever analyzing data from aquifer tests in mine spoil, these potential problems must be kept in mind. In spite of the problems encountered during slug testing of spoil, the aquifer hydraulic parameters derived and the slug responses observed remain useful in the hydrologic characterization of a mine site.

Jan 1, 1994

By John K. Adams

Phosphorus may be incorporated into sedimentary rocks in at least four different ways: (1) by the accumulation of detrital mineral fragments, (2) by the accumulation of phosphatic organic debris, (3) by diagenesis and (4) perhaps by the primary precipitation of calcium phosphate. Based-on the petrographic examination of Cretaceous and Tertiary sediments from the northern and central parts of the Atlantic Coastal Plain, Diagenesis is the most important of these mechanisms. Both syndiagenesis and epidiagenesis are required to explain the origin of all the diagenetic phosphate mineral species which occur in the northern and central parts of the coastal plain. Syndiagenesis produced much of the coastal plain's apatite. It was operative below the sediment-water interface while the substrate was being compacted. Compaction forced pore waters, which were enriched in phosphate by the decomposition of organic matter, upward through calcareous sediments. The PO43- radicle replaced the CO23- and calcareous nodules, pellets and shell fragments were converted to apatite. Epidiagenetic reactions occurred in the subaerial environment where downward percolating meteoric waters carried phosphate in solution to cites where cation activity was sufficiently high to form new minerals. Vivianite may form where ferrous iron is available and wavellite and variscite may form in the presence of aluminum rich minerals. Textural evidence suggests that many of the reactions were repeated. The present day appearance of apatite, vivianite, wavellite and variscite in the coastal plain may represent several generations of diagenesis.

Jan 1, 1972

By B. R. T. Simoneit

The conversion of organic matter to petroleum by hydrothermal activity is an easy process, occurring in nature in many types of environments. Geologically immature organic matter of marine sediments is being altered by this process in Guaymas Basin (Gulf of California), Escanaba Trough and Middle Valley (northeast Pacific), Bransfield Strait (Antarctica), and Atlantis 11 and Kebrit Deeps (Red Sea). Contemporary organic detritus and viable microorganisms are also converted in part to petroleum-like products by the same process when present to become entrained, as for example on the East Pacific Rise at 13o N and 21o N and on the mid-Atlantic Ridge at 26oN. The hydrocarbon products (methane to asphalt) generated in all these areas have been elucidated in terms of composition, organic matter sources, and analogy to reservoir petroleum. This petroleum represents a major input of carbon to the primary chemosynthetic productivity of hydrothermal vent systems and may be important to interactions with metals in hydrothermal ore formation.

Jan 1, 1991

By Al. Valero, A. Domínguez

This paper appraises the energy requirements for mineral production through an exergy approach taking into account the long-term decline in ore grades. In this context, the exergy required for restoring resources from the dispersed state of the so called Crepuscular Earth into the physical and chemical conditions in which it was delivered by the ecosystems in light of the available technology, is known as exergy cost. The exergy cost is the point of reference in order to evaluate in a single variable, characteristics such as composition, concentration (ore grade) and the state of technology. The ratio between the exergy cost and the minimum thermodynamic cost required to accomplish the same process is called unit exergy cost and provides a measure of the irreversibility of the analyzed processes. Otherwise, the ore grade is one of the main issues which affects directly the costs associated with mining the ore. Hence, the unit exergy costs to produce minerals from progressively lower ores grades by the current technology is analyzed. The unit exergy cost curves are presented for some important minerals such as aluminium, chromium, cobalt, copper, gold, lead, manganese, nickel and zinc, in order to know the trend when the ore grade decreases.

Jan 1, 2011

By P. R. ZETTWOOG

HISTORICAL BACKGROUND A program in France to develop personal [a] dosimeters has been initiated 1974. The patent on which is based the present device was obtained in 1972 * . From 1972 to 1974, the possibilities of applying certain ionograph track detectors to the spectrodosimetry of radon daughters was explored. The first prototype were produced in 1974. It took four years (from 1974 to 1978) to produce an autonomous dosimeter whose components has a sufficient life span, especially for the turbine motor unit. Qualification in the laboratory was obtained in 1977. In 1978 it was obtained in the mine for technology (autonomy of 12 hours and a life span of more than one year) and in 1980 for monitoring. 300 dosimeters have been tested in underground mines all together. Indispensable peripheral equipment were also developed from 1976 to 1980 : calibration devices, equipment to prepare and develop the films, read out systems. The concept of an "Integrated System of Individual Dosimetry" (ISID) based on a personal [a] dosimeter measuring exposure to radon daughters, thoron daughters, ore dust and external irradiation doses was proposed at the end of 1980. Since January 1st 1981, ISID is used on a routine basis in some french mines, situated in remote area, and appears to be very competitive with the ambiant dosimetry. The latest version of the dosimeter is produced in mass series since June 1981 and should equip all french mines in 1982. DESCRIPTION OF THE INSTRUMENTATION DEVELOPMENT OF THE DOSIMETER MEASURING HEAD The measuring head is based on the use of ionographic film to detect a tracks. In fact, the measuring head is a spectrodosimeter which measures separately over the period of exposure: - the potential [a] energy inhaled due to the decay of Po 218, Po 214, and Po 212 ; - the number of Rn 222 atoms inhaled ; - the inhaled total [a] activity of the five long-lived emitters present in the ore dust. The contribution to the total inhalable potential [a] energy of these various radionuclidesin a typical underground mine is studied in Appendix I. The measuring head described in detail in Appendix II, is able to satisfy all the implications made in the ICRP recommendations. Appendix III deals with the use of this measuring head in the cases where the equilibrium factor is lower than 0.1. This situation occur in open-pit mines where account must be taken of the Rn 222 contribution, which is no longer negligible in relation to that of its daughters. CURRENT DOSIMETER PERFORMANCES Table I shows the characteristics of the latest dosimeter. Appendix IV should be consulted concerning qualification of the dosimeter in the laboratory and in mines, technological development which finally produced the [a] dosimeter and its peripheral equipment, and technical presentation of the ISID (Integrated System of Individual Dosimetry) based on the concept of a multirisk personal dosimeter. Data on the installation and operating costs of such a dosimeter, which would seem to be competitive, are also given in this Appendix. ADVANTAGES OF PERSONAL DOSIMETRY AS COMPARED TO AREA MONITORING The results of the first eight months of experiments carried out under real conditions in an underground mine site are given in detail in reference 8. Area monitoring : The monthly exposure per worker to inhaled Rn 222 was determined from the knowledge of time spent in various areas of the mine and for the different mining operations, as well as from numerous and systematic sampling of the Rn 222 concentration in all work places. Personal dosimetry : The exposure to potential energy from radon daughters was measured by an [a] dosimeter developed by the CEA and worn by each of the 160 miners during eight months. In this way 160 x 8 pairs of monthly individual exposure values have been obtained which can be statistically studied. This test was decisive for us because it proved that the [a] dosimeter was technically sound (very few defects over one year for 160 dosimeters) and especially that personal monitoring devices were superior to area monitoring devices. The following conclusions can be drawn 1. The exposure distribution obtained by personal dosimetry is log-normal. This is true for the results on the whole as well as for groups of results relating to certain explanatory variables. See fig. la, 1b, 1c. 2. The exposure distribution obtained by area monitoring does not correspond to any type of distribution. If the results of personal monitoring are taken as a reference, area monitoring tends to underestimate the high exposures and overestimate the low exposures.See fig. 2. 3. [a]-energy exposures are underestimated when calculated from radon exposures and the equilibrium factor found in the considered mines. This is due to episodes or to zones of high radon concentrations not registered

Jan 1, 1981

By R. W. Bartlett

Computer deterministic models for predicting the time dependent extraction of copper by leaching fragmented rock (both in situ and heaped or piled) have been presented in the last two years by Bartlett1, Braun, Lewis and Wadsworth2 and Roman and Co-Workers.3 All of these models involve aqueous diffusion within the pores of the rocks from which the metal is being extracted. The rate of chemical dissolution of the ore mineral within the rock will also affect the kinetics in the case of sulfide copper ores and some of the more refractory oxide copper ores. Simulation is also needed for fine grain disseminated gold ores and low grade uranium ores that may be heap leached. The development of such leaching models has two major purposes: First, extraction estimates must be made for tong time periods particularly for situations where laboratory and field tests either cannot be made or where there is insufficient time for field testing. Second, the results of simulated leaching should indicate the relative importance of the extraction controlling parameters and, thereby, provide a better understanding of the complex leaching phenomena on heaped material being leached, and guide further experimental work.

Jan 1, 1974

By Raymond A. Povirk, David L. Bartsch, James V. Hamel

The Ohio Valley Coal Company is expand- ing its Powhatan Mine No. 6 near Alledonia, Ohio. This expansion includes a 20 rn (65 ft) height in crease for an existing 44 rn (145 ft) coal refuse - slurry impoundment dam. The dam is being raised by upstream construction which will involve placement of more than 15 m (50 ft) of new fill over an existing reinforced concrete decant structure. This structure is 0.76 rn (30 in.) square inside and its deepest portion was under 24 m (80 ft) of coal slurry and water. The top of the decant structure was not strong enough to safely support the new fill and, because of the slurry and water, there was no way to reinforce the structure from the outside. The structure was reinforced frorn the inside by sliplining 73 m (240 ft) of 0.66 rn (26 in.) OD, 0.53 rn (21 in.) ID polyethylene pipe, grouting around this pipe with cellular concrete. and constructing a steel-fiber reinforced micro-silica concrete transition at the upslope end of the pipe. Rehabilition of the decant structure was completed in August 1989. The rehabilitated decant structure is now performing satisfactorily as fill is being placed over it for raising the dam.

Jan 1, 1991

By B. Grosso

The National Italian Regulation concerning environment protection imposes that industrial areas are provided with systems aimed at preventing the circulation of contaminated groundwater. These systems can be static or dynamic and operate basically by intercepting the contaminated flow. Their effectiveness, realization time and costs depend on the intervention type and on the features of the specific site. The selection of the best solution is complex and the results obtained by this selection may be affected by residual risks related to the uncertainty of the hydrogeological and geotechnical characterization of the site. With regard to the industrial area of Portovesme, located in the south of Sardinia, the paper presents the analysis of alternative interventions aimed at the protection of the groundwater. The attention is focused on the evaluation of their effectiveness, impact on environment and, finally, time and costs of construction.

Jan 1, 2008

By C. L. Schaidle

Computers and communications technology have revolutionized many industries. In earthmoving, this revolution has just begun. The major changes are still to come, but they are just around the corner. This paper presents a vision of this up-coming revolution in our industry. This vision is comprehensive. It includes basic communication, machine monitoring and diagnostics, job and business management, planning and operations, and machine control. For our industry to realize maximum benefits from the information age, we must have a vision of the future that is shared by technologists, machinery producers, and miners.

Jan 1, 1994

By R. J. Weege

Conventional underground mapping methods and diamond drilling are being applied in a study to determine the nature of the copper ore occurrences near the footwall of the Osceola lava flow top, commonly referred to as the Osceola Amygdaloid. Our work to date suggests that structures formed by relatively impermeable barriers, created by flowage and injection of still-molten lava from the interior of the flow into the solidified, brecciated crust, acted as the ore receptacles. Ascending hydrothermal fluids traveling near the footwall contact were trapped and confined in these barriers which retarded the direct upward movement of the ore fluids and caused deposition of copper. Oreshoots located near the footwall appear to have been formed spatially' independently from the hanging-wall oreshoots by fluids traveling simultaneously, but along different channelways. The barrier concept as advanced by earlier writers to explain the concentration of the ore-bearing, fluids into broad shoots con¬stituting entire ore bodies is found to be equally as applicable for the localization of smaller oreshoots within the Osceola ore body.

Jan 1, 1962

By Florian Festge

It has been said that good things come in threes. In the case of screening for mining and quarry operations, profit comes in three distinct phases: layered, basic and sharp screening. But how good they are ? whether they maximize efficiency and improve the potential for success ? depends on having the right screen media on the deck for each of the three phases. A relatively new method for achieving that goal is a blended screen media approach that incorporates the ideal screen media for each phase and the ideal mix of media for the process overall. The goal in implementing a blended solution is to find the optimal combination of open area and durability. If this combination is found, maximum product quality and profits will be realized by increasing efficiency of classification while minimizing downtime and maintenance costs.

Jan 1, 2012