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By Christopher Mark

The first International Conference on Ground Control in Mining opened with the topic of pillar design. Two classic papers were presented, one by Bieniwski and the other by Wilson. Unfortunately, the two methods were so radically different from each other that it was nearly impossible to reconcile them. Adding to the confusion were the many other pillar strength formulas (such as the Salamon-Munro, the Holland-Gaddy, and the Obert-Duvall, just to name a few) that were also available. Little wonder that discussions of pillar design in those days often ended with anguished cries of ?but which formula is the right one?? The past 25 years have seen substantial progress in the science of coal pillar design. Indeed, one testament to the improvement is the relative scarcity of papers on the topic at recent Conferences. Two factors have been largely responsible for the progress that has been made. The first has been the collection of large data bases of actual case histories of pillar performance in a variety of settings, from shallow room-and-pillar mines through deep cover longwalls. These have made possible the development of empirical design procedures that are closely linked to real world experience. The second important factor is the development of sophisticated computer models that can accurately simulate pillar behavior and roof/pillar/floor interactions. Together, these two lines of research have led to a new understanding of pillar mechanics that identifies three modes of pillar failure: ? Sudden, massive collapse, accompanied by airblast, for slender pillars (width/height<4) ? Squeezing, or slow, non-violent failure, for most room and pillar applications (4<w/h<10) ? Entry failure or bumps for deep cover and longwall applications (w/h>10) It is particularly satisfying that the insights gained from numerical models broadly support those obtained from the empirical studies. While far less controversial than in the past, pillar design problems continue to arise. One recent example is pillar design for highwall mining. NIOSH has just released a software package, called ARMPS-HWM, which employs a number of modern pillar design concepts. Since highwall mining web pillars are long and slender, the greatest danger is that of a sudden collapse. ARMPS-HWM suggests two possible prevention strategies, one which concentrates on the SF of the webs, and the other which creates a ?pressure arch? using properly sized barrier pillars. The paper will close with a discussion of some current needs in coal pillar design, including: ? Updating older empirical methods, such as ALPS, where changes in technology (new types of roof support, more demanding ventilation requirements, faster retreat rates) may have made some of the original case histories obsolete. ? Methods for determining site-specific coal strengths, focusing on bedding plane strength and other factors that may effect confinement, as input for both empirical and numerical design. ? Improved methods for evaluating coal pillar performance for environmental issues, such as surface subsidence and hydrologic impacts, which consider such factors as depth, w/h ratio, water immersion/drainage, and time dependent seam strength.

Jan 1, 2006

By Campbell Brown GA

IN 1904-5 diamond drilling operations in the Mount Morgan mine proved the presence of some inillioils of tons of rich, copper-gold ore, averaging about 45% to 50% silica and 22%Fe as sulphide. To smelt this ore in blast furnaces, without previous concentration, large quantities of basic flux.were required. Unlimited quantities of cheap, limestone, were available at Marmor, on the GladstoneRockhampton railway, 50 miles from Mount Morgan, but the supply of iron flux was a more difficult problem. Smelting operations started, with one&apos; furnace in January, 1906, using as flux low-grade sulphide ore fro:m. the mine, containing very little silica. When the second, furnace was blown in this was supplemented by ironstone from, small aeposits in the immediate district. It was recognized that these sources of supply would be insufficient to keep the full plant going after the third furnace had been blown in. Accordingly, the deposits at Eabra and Mount Etna were opened, neither of which proved capable of supplying the quantity required viz, 1000 tons per week. Negotiations were meanwhile being conducted with the Marble Island Iron and Limestone Co. to obtain the right to mine at Iron Island, where a sufficiently large deposit was known to exist. Shipments from this source commenced in January, 1907, and ceased at the end of July of this year, when the metallic flux from...

Jan 1, 1912

By Gaspard Devos

1. A NEW CONTEXT FOR METAL INDUSTRY Producers and owners of industrial extractive sites are living hard times due to Environmental pressure and liabilities. This is valid whatever the region in the world, it is just a question of time. On one hand, the normative environmental pressure is increasing through more severe regulations and controls on all pollution sources and production materials. [ ] Furthermore, more impurities are extracted and captured, more the volume of the related wastes is increasing. But disposal costs are increasing, disposal areas for wastes are restricted, markets for wastes are limited and technologies for waste treatment are, most of the time, not available. On the other hand, for most of the extractive industries, the costs required to get access to refine primary raw material are killing the profitability of the industry. Definitively, a technological and economical breakthrough is ongoing: extractive industries have to increase their feed from secondary material and to be involved more and more with the recycling business.

Jan 1, 2005

By L. C. Stone, J. C. Parr, T. N. Anderson, D. Metcalf

An increase in the importance of low-grade materials as sources of gold and silver has led to the need for improved analytical methods on leach solutions, ores and various effluents, residues, and in-process streams. These are required by plant operators as guides to process control and for accounting pldrposes. Atomic absorption spectrophotometry (AAS) and AAS preceded by pre- concentration have been applied successfully to resolve many such problems. However, AAS is no panacea and imprecision or loss of accuracy can result if adequate precautions are not taken to prevent losses and eliminate interferences. The recent methods are discussed together with methods for overcoming difficulties. Comparisons with more classical analytical techniques are also given.

Jan 1, 1981

By Donald Leroux, Martin Suichies, Andy Trusiak, Chris Dechert

"In modem concentrators, the operation of flotation machines is often stabilized by simple control loops. Froth level, slurry density and aeration rate are all physical parameters typically controlled through classical PID loops. Few concentrators, however make use of advanced computing technologies for controlling the grade of flotation product streams. Technical challenges such as long process delay and the long and uneven sampling interval of on-stream XRF analyzers often restrain their implementation. Model Predictive Control (MPC) is known to have better performance than PID for controlling processes with long delays (such as flotation circuits). This paper describes the implementation of a multi-input/single-output (MISO) MPC algorithm and an FIR model identification routine using an object-oriented graphical computing environment.The MPC module (controller and identification) was implemented on an industrial control system and applied to many sulfide flotation circuits in the Brunswick Mining concentrator (New Brunswick, Canada). In most cases, the manipulated variable was the collector addition. As long as it is provided with decent process models, the performance of the MPC controller is good on all the flotation circuits on which it was applied. Significant reductions of grade variance are reported and the controller responds well to set-point changes. The user-friendly, graphical nature of the computing environment led to a high degree of acceptance by both the process engineers and the flotation operators.1. INTRODUCTIONOver the past three decades, much instrumentation has been developed for flotation machines. The introduction of instruments such as pulp density gauges and cell level probes was particularly well received by the plants where pneumatic and electronic controllers were available for implementing PID control loops. In a way, these simple loops revolutionized the mineral industry. The operation of flotation circuits could then be stabilized through the use of automatic controllers."

Jan 1, 1999

By P. J. Rua

The Piedras Verdes copper mine is a new run-of-mine (ROM), heap leach, solvent-extraction/electrowinning (SX-EW) operation located 21 km (13 miles) north-northwest of the town of Alamos in the state of Sonora, Mexico. The Piedras Verdes copper mine is wholly owned by Frontera Copper Corp. (FCC), a Canadian corporation, through its 100 percent beneficial interest in Cobre del Mayo S.A. de C.V. (CDM), a Mexican registered company. The January 2008, minable reserves were estimated to be 193.6 Mt (213 million st) at a grade of 0.36 percent copper. The overall recovery of total copper was estimated to be 61.9 percent. The property has an additional 17-year life and is designed to produce 31.7 kt/a (70 million lbs/year) of cathode copper. Construction commenced in early October 2005. The first copper cathode was produced 12 months later at a total capital cost of $100 million. Elevations at the site range from 150 to 300 m (490 to 985 ft) above sea level. The area has excellent infra-structure in the form of towns, power, water, roads, rail, airfield and access to the deepwater port of Guaymas (Fig. 1). The surrounding area is also famous for its numerous polymetallic (lead, zinc, copper, silver and gold) epithermal veins. Some of these were mined for more than 200 years and provided the wealth on which the town of Alamos was built. The original village of Piedras Verdes was located in the area of the proposed openpit mine and, consequently, it was necessary to construct a new townsite 6 km (3.7 miles) to the south before project development could commence. The new town site (Fig. 2), complete with power and water supplies, roads, sewer system, schools, clinic and recreational facilities, was completed and occupied by 49 families in September 2005. CDM received its remaining permits from the Mexican environmental authorities on Sept. 20, 2005. This enabled the company to proceed with full-scale development. CDM owns or controls 27 mining concessions covering the resource. Surface rights to the Piedras Verdes project were controlled by four Ejidos (communal agrarian and/or ranching societies) and five individual landowners. CDM has acquired all surface rights necessary for its mining operations and associated facilities either through outright purchase or long term lease agreements.

Jan 1, 2008

By Staff

The mineral sector is a fundamental part of the U.S. economy. It contributes to the real gross domestic product (GDP) at several stages—basic (mining), intermediate processing, manufacturing of finished goods and construction. The estimated growth rate for the real GDP of the United States for 2006 was 3.2 percent. The nominal GDP was about $13.2 trillion. The value of minerals mined in the United States in 2006 rose significantly because of increased unit price for some metals—particularly copper, zinc and other base metals. There was also a significant reduction in metals stocks. Infrastructure expansion and manufacturing in China and India have been absorbing a significant portion of world output. Domestic production increased for some industrial mineral materials, mainly cement and construction sand and gravel. Production of crushed stone declined less than 1 percent in 2006 compared

Jan 1, 2007

By R. D. Short

Environmental regulations for noise and air pollution are directly affecting the type of equipment and construction techniques being utilized for pile driving construction using diesel hammers in California and elsewhere. Consequently, the cost of construction is increasing and in some cases, the use of diesel pile hammers has been prohibited. Based on the trend in California and elsewhere in the world, environmental constraints are spreading and becoming more restrictive. The City of Tokyo, Japan, for example has banned the use of diesel hammers. Environmental restrictions on diesel hammers can be satisfied by using modern hammers, clean burning fuels, synthetic lubricants and pre-excavation techniques.

Jan 1, 1989

By D. Washington

The US economy and the demand for nonfuel minerals grew at lower rates in 1995 than in 1994. Demand for major metals, such as aluminum, copper and steel, was mixed but relatively stable. The building industry, including highway construction, helped to support modest overall growth in demand for industrial minerals. The value of processed materials of nonfuel mineral origin produced in the United States during 1995 was estimated to be $395 billion, an increase of almost 10%compared with 1994 (Fig. 1). The estimated value of US raw nonfuel minerals production during 1995 was $38billion, about 7% more than in 1994. The value of US minerals production has increased in 30 of the last 35years.

Jan 1, 1996

By R. V. Mrazek, F. E. Block, S. B. Knapp

The mixed homogeneous and heterogeneous kinetics of the thermal decomposition of tungsten hexacarbonyl were studied by employing a batch reactor. The system was such that a sample of tungsten hexacarbonyl could be injected into the preheated reactor, and the progress of the reaction followed by a simple pressure measurement. Both the homogeneous and heterogeneous reactions were found to be first order, and approximate activation energies were determined for each reaction. It is shown that the dis-proportionation of carbon monoxide to give carbon and carbon dioxide cannot be the source of carbon in tungsten deposits prepared by this reaction. The kinetics of the thermal decomposition of tungsten hexacarbonyl have been investigated as part of a continuing study by the U.S. Bureau of Mines on the decomposition of organometallic compounds. Reactions involving the thermal decomposition of metal carbonyls have a potential application in the preparation of pure metals and fine metal powders. Indeed, it was these applications which provided the impetus for much of the early work involving the carbonyls of nickel1 and iron.&apos; The relative lack of study of other metal carbonyls can be traced to the comparative difficulty in synthesizing these compounds. The most common use for tungsten hexacarbonyl has been as an intermediate in vapor-phase plating.7&apos;8 However, attempts to obtain a carbon-free deposit of tungsten by this method have not been successful, and some investigators have taken advantage of the carbon contamination and used this process to form tungsten carbide deposits.lo Other investigators have studied the thermodynamic properties11"14 and molecular structure of tungsten hexacarbonyl. However, very little is known about the kinetics of this thermal decomposition, the mechanisms involved," or the source of carbon in the resulting plate. In contrast, studies have been made of the kinetics of the thermal decomposition of nickel tetracarbonyl, iron pentacarbonyl, and molybdenum hexacarbonyl.&apos;l It has been found that these thermal decompositions occur by a mechanism which is partially heterogeneous in nature. Information available on the equilibrium constants for the decomposition of tungsten hexacarbonyl was used to determine a temperature range, 500" to 560°K, in which the reaction could be expected to be essentially complete. APPARATUS The apparatus used allowed the injection of a sample of tungsten hexacarbonyl into a preheated batch reactor and the use of a simple pressure measurement to follow the progress of the reaction in the sealed reactor. The pressure was sensed by means of a pressure transducer (Consolidated Electrodynamics Corp., 0.3 pct)* capable of operating at the *Reference to specific products is made to facilitate understanding and does not imply endorsement of such brands by the Bureau of Mines._______ reaction temperature. This type of sensing element was chosen to avoid the problem of condensation of the sublimed carbonyl in the capillary tubing leading to any type of remote pressure-sensing device. stirring was provided by rotating the entire apparatus. Glass beads placed in the reactor provided a pulsating agitation. To minimize thermal gradients in the reactor walls, the reactor was constructed of aluminum. The support tube which held the reactor in the furnace was thin-walled stainless steel to minimize heat conduction out of the reactor. As a result of these measures, a nearly uniform temperature (°C) was maintained throughout the reactor. Fig. 1 is a schematic diagram of the apparatus. The small gear motor rotated the entire apparatus at about 200 rpm. The bearings shown at the ends of the air cylinder were perforated to allow air to be fed to the charging piston and to allow inert gas to be fed to the reactor during the preheating period. The sample was simultaneously injected and sealed inside the reactor by operation of the air piston. Fig. 2 shows a cross section of the air cylinder and the adjoining portion of the support tube leading to the reactor. The sample carrier is shown in place at the right-hand end of the injection rod extending from the air piston. The piston is shown in the retracted position, as it would be prior to the start of an experiment. The small Teflon gasket which encircled the sample carrier at the end of the injection rod sealed the reactor when the sample was injected. This seal was maintained throughout the test by maintaining air pressure on the piston. The sample carrier was a 2-in. section of thin-walled, -in.-diam nickel tubing with an internal blank about 1 in. from the base and with the base end sealed.

Jan 1, 1969

By G. H. Wilson

INTRODUCED in 1946 to serve a need in power-plant operation, closed-circuit TV has been used by well over 200 organizations in approximately 25 different industries. Known as industrial television, or simply ITV, it can be described as a private system wherein the television signal is restricted in distribution, usually by confinement within coaxial cable that directly connects the TV camera to one or several monitors, Figs. 1, 2. The picture is continuous and transmission is instantaneous, permitting an observer to see an operation that may be too distant, too inaccessible, or too dangerous to be viewed directly. Destructive testing or the machining of high explosives can now be conducted hundreds of feet away by personnel who still have close control through the eyes of the TV camera. It is also possible for one man to control operations formerly requiring the co-ordinated efforts of several workers. For example, at a large midwestern cement plant conveyance of limestone from primary crusher to raw mill and loading into five storage bins once necessitated the work of two men, one having little to do but prevent spilling of material by manually moving the tripper on the belt conveyor as occasion required. TV cameras mounted on the tripper now provide bin level indication to the conveyor operator at the crusher position so he is able to control the entire loading operation remotely, Fig. 3. By means of a switch, the picture from either camera is alternately available on a single viewer, or monitor, Fig. 4. Each camera is mounted on the tripper by means of a simple adjustable support and looks down into the bin, which is identified by the number of cross members on the vertical rod. Each associated power unit is located on a platform above the camera, Fig. 5. This centralized control by means of TV often has produced superior results, and in many instances saving in operating costs has been sufficient to write off equipment costs within six months to a year. Where a key portion of a process may be enclosed or otherwise inaccessible, TV again reduces the likelihood of mistakes and permits closer control by making available to the operator valuable information he might otherwise never possess. An example of this can be found at a strip mine where the coal seam lies 50 ft or more below the overburden, which is removed by a large wheel shovel. From his centrally located position the shove1 operator was unable to judge accurately to what extent the wheel buckets engaged the earth. His chief indication of efficiency was the amount of overburden on the belt conveyor as it passed his control point 75 ft from the wheel. Now, two television cameras mounted on the tip of the boom permit the operator to view the wheel from each side and provide him with a close-up view of the buckets so that he can take immediate and continuous advantage of their capacity, quickly compensating for ground irregularities and avoiding obstructions, Fig. 6. While the word television conjures up visions of highly complex and intricate apparatus such as that employed in modern TV studios and transmitting stations, the term industrial television should indicate compact, straightforward equipment. Most present-day ITV systems contain fewer than 25 tubes including camera and picture tubes. The average home television receiver alone requires at least that many tubes. Equipment like that illustrated in Fig. 1 contains only 17 tubes, of which 3 are in the camera. It can operate continuously and dependably, without protection, in any temperature from 0" to 150°F. It consumes less current than a toaster and weighs under 140 lb. Camera and monitor may be separated by 1500 to 2000 ft and by greater distance with additional amplification. This equipment is designed to withstand vibrations up to 21/16 in. and will operate successfully under more severe conditions of vibration and heat when suitable enclosures are provided. Any number of cameras may be switched to a single monitor, and any number of monitors, within reason, used simultaneously. Two types of applications in the mining industry have already been described. A third under serious consideration by several organizations will make use of ITV for remote observation of conveyor transfer points at copper concentrating plants so that evidence of belt breakdown and plugging of transfer chutes can be spotted immediately and costly overflow of material avoided. A television camera will soon be installed to view a trough conveyor near the exit of an iron-ore crusher to indicate clogging of the crusher as evidenced by reduction or absence of material on the

Jan 1, 1955

By C. E. Richards, C. N. Reid

The influence of preferred orientation on the incidence of defbrtnation tuinning has been studied. High-purity iron with almost vandonz grain orientation was cotnpared uitll iron of the sa)ne grain size and composilion lza,ing a strong (110) fiber texture. As expected from published work on single crgslfls, /he ))lean stress for the onset of luitzning-, and the l,olu)nt. fraclion of twinned nzaterial obserlled in lension differed fron the 1-a1ue.s it2 co?nPression for tnolerial with a slrong texlure. The llinning stress of "rctndorrl " )zalerial did not 17ary with the sense of the aPPlied unin.via1 stress, but sirprisinglg the incidence of 1c)i)zning- was about three 1i))zes greater ill conzp?&apos;ession Illon in lension. These results (Ire attributed entirely to ovienbation and may be nderslood in ler?ns of the shear slresses acting on the allowed twinning syster)is. J. HE twins most commonly formed in bcc metals may be described as regions of the crystal in which a particular set of (112) planes is homogeneously sheared by 0.707 in the appropriate ( 111) direction. A similar twin-related crystal could be produced by a shear of 1.414 in the reverse (111) direction but twinning by this large displacement has never been reported. Thus, twinning is unidirectional and a shear stress which produces twinning does not do so when its sense is reversed. The sense of a shear Stress is reversed when the loading is changed from tension to compression, or vice versa. Consequently, for a given orientation of a crystal relative to a uniaxial stress, only a fraction of the twelve (112) twinning systems are geometrically capable of operating in tension, and the remaining systems may operate only in compression. Therefore, when twinning is involved, there are expected to be differences in behavior between crystals tested in uniaxial tension and those tested in compression. This has been verified experimentally by Reid et 01.&apos; and Sherwood el al.,&apos; although a critical stress criterion was not encountered. Furthermore, twinning stresses in colmbium," tungten, tantalum,&apos; irn,&apos; i-Fe,\ nd molybdenum7 single crystals have been shown to depend critically on orientation, although again twinning did not occur at a critical value of the macroscopic shear stress. However, when twinning occurs, it generally does so on the most highly stressed systems, 1--4&apos;6&apos;8&apos;9 implying that the stress level does have some relevance to twin formation. In view of the large orientation dependence of twinning in bee single crystals, it might be expected that such an effect would be present in poly crystalline material which possesses a recrystallisation texture. Indeed, riestner" showed that the twinning stress in tension is very orientation-sensitive it1 <&apos;grain-oriented, silicon-iron;" this material possessed a very strong t c m^ii a nnr x_____k . i-_ii__ ri_______j. _x r»i_._:__i preferred orientation obtained by secondary recrystallisation. Reid et a/.&apos; observed a marked difference in the tensile and compressive yield stresses of polycrys-talline columbium which was rationalised in terms of the effect of a preferred orientation on twinning. No other such illformation is known to the authors. Several investigations of twinning in polycrystalline bcc metals have been reported in which the possible existence of a preferred orientation was not even mentioned. It is the purpose of this paper to show that there is a strong effect of texture on twinning in polycrystalline iron, and to poilt out the difficulty in eliminating preferred orientation in recrystallised metals. 1. EXPERIMENTAL METHOD Material and Specimen Preparation. Low-carbon, high-purity iron was obtained from the National Physical Laboratory in the form of $-in. diam rod which had been cold-swaged from a diam of 1 in. The composition of the material is given in Table I. The as-received bar was cold-swaged directly to 0.185 in. diam from which cylindrical tensile and compression specimens were machined. Specimen geometry is illustrated in Fig. 1. The gage length was 0.30 in. long and 0.10 in. diam; it should be noted that, apart from the extra heads which are necessary for tensile loading, the geometry and dimensions of the two types of specimen are identical. The specimens were heat treated either by sequence A or B outlined in Table 11. The essential difference between these two treatments is that in one case the material was repeatedly cycled through the y- to a-phase change in order to produce grains of almost random orientation ("random" iron)

Jan 1, 1969

A mining engineer from South Africa, whose research has taken him to some of the world?s deepest gold mines, is the winner of the St Andrews Prize. Daniel Limpitlaw, 27, picked up a cheque for $25,000 for his dissertation on reversing the damage done by early mining technology, which he claims is partly responsible for blighting the urban environment in many South African cities. Launched in October 1998 by the University of St Andrews and international energy company Conoco, the St Andrews Prize sought practical solutions to environmental problems. It attracted interest from 450 individuals and groups from countries as diverse as China, Pakistan, Canada, New Zealand, Germany, the UK and the United States.

Jan 1, 1999

GENERAL CONTRACTOR: ALEXANDER CONSTRUCTORS, INC. STRUCTURAL ENGINEER: CAGLEY & ASSOCIATES, INC. GEOTECHNICAL ENGINEER: F.T. KITLINSKI & ASSOCIATES, INC. PILE FOUNDATION CONTRACTOR: L.G. BARCUS AND SONS, INC. PROJECT PROFILE: 108-10 in. diameter AugerPiles installed to an approximate depth of 32 ft. Piles were installed through Stiff Clayey Fill and Medium-Dense Sands to Decomposed Shale. Piles were drilled to a refusal criteria of 1 ft. / 3 min. Piles were installed using a Barcus Mantis AugerPile rig which is large enough to install piles 25 to 50 ft. long outdoors. The Mantis is also ideal for indoor and low overhead installations. On top of being extremely versatile, the Mantis is also very economical to mobilize. The existing structure is supported on H-Piles. The AugerPiles were furnished and installed for less than the material price of the H-Piles. Design loads were under 40 tons which eliminated the need for a load test. AugerPiles were selected for minimal vibration, limited noise, and economy.

Jan 1, 2001

By Eder Villarreal

Existen concesiones mineras en estado de prospección o exploración básica para las cuales, debido a que no cuentan con recursos o reserva mineral definidos, es muy difícil establecer un valor. La metodología que aquí se presenta muestra la forma de valorizar dichas concesiones mineras desde el punto de vista de costos y una serie de variables geológicas y económicas. El proceso consiste en calcular un costo base, realizar una evaluación cualitativa sobre la base de 10 variables, asignarle un peso a cada una de ellas y realizar una operación matemática utilizando dos ecuaciones.

Sep 20, 2019

Provide optimum visibility of mining operations while maintaining protection and comfort for ma-chine operators. Approach Cabs and canopies with hydraulically powered variable-height control were developed for several machines and tested in underground mining operations. How It Works From his position in the cab, the operator can raise or lower the cab, selecting a height that offers either more visibility of the working place or greater clearance for tramming. The entire cab enclosure moves up and down on guide rollers that ride on a pair of rails, and is actuated by a hydraulic cylinder controlled from within the cab. Normal working heights, for each of the four different cabs developed, are with the cab bottom from 6 to 8 inches above the mine bottom. A typical range of elevation (excursion) afforded by this design is shown in Figure 1.

Jan 1, 1978

By M. F. Bucek

This report summarizes the activities performed and the results achieved during a two-phased investigation of the technical and economic feasibility of disposing of coal mine refuse underground in active mines, Three coal regions in the United States that are most severely affected by coal refuse disposal problems are identified: southwestern Pennsylvania, southern West Virginia, southwestern West Virginia and eastern Kentucky. For each region, a conceptual mine model is presented that describes the geologic conditions, mining methods, and environmental circumstances typical of that region. The model mine that was prepared for the Kanawha Region in Southwestern West Virginia and eastern Kentucky was selected as the basis for developing alternative conceptual designs of underground disposal systems in the second phase of this investigation. Procedures used in selecting the regions and in modeling typical mines are described in Part I of the report. Part II of the report describes existing methods for stowing refuse underground, presents three alternative conceptual designs of stowing system that would be appropriate for the model mine postulated in the first phase of the study, discusses technical characteristics and environmental effects relative to the various systems, and evaluates the technical and economic feasibility of the three alternative disposal system designs. Comparisons costs among systems and with costs or surface disposal are presented.

Jan 1, 1980

By Marco Larghi, Jurg Knobel, Braden Schmidt

Remote Avalanche Control Systems (RACS) which uses solid explosives has been used in Europe since 1996 and North America since 1999. With large destructive avalanches in transportation corridors, various States and Provinces have started implementing RACS into their summer construction projects to minimize traffic shutdowns. Since 2014 in North America, many of the projects are requiring the RACS deployment boxes to be removable by light duty helicopter for loading and summer storage. This is to further remove workers from the mountain tops, where inclement weather and Occupational Health and Safety concerns are widespread. We did not believe the method of flying primed charges under a helicopter was safe, so we developed a new charge container to deal with the issue.

Feb 1, 2020

By W. G. Pariseau

This contribution describes rock mechanics features of the Davis Cavern at the former Homestake Mine in Lead, South Dakota, U.S.A. The mine is located in the northern Black Hills of South Dakota. In 2003 and again in 2008, the mine site was recommended for development as a national Deep Underground Science and Engineering Laboratory (DUSEL) in cooperation with the Sanford Underground Science and Engineering Laboratory under the South Dakota Science and Technology Authority (SDSTA). The original Davis Cavern was excavated about 9.1x16.8x9.7 m high (30x55x32 ft high) in 1965 (Mitchell 2009) at a depth of 1,478 m (4850 ft). The purpose of the cavern was to house apparatus for detecting solar neutrinos. The experiment ultimately proved successful and earned R. Davis a share of the 2002 Nobel Prize in physics. Recently, a new experiment (LUX=Large Underground Xenon detector for dark matter particles and WIMP&apos;s=weakly interacting massive particles) was proposed for the Davis Cavern that required an increase in height of 2.4 m (8 ft). For many years, the Homestake gold mine was the deepest operating mine in North America. Development extended to the 8000 Level (2,438 m). The mine closed in 2003. Pumps were shut off and the water level rose to the 4350 Level, about 150 m (500 ft) above the Davis Cavern. Some six years later after selection for DUSEL proposal development by the National Science Foundation (NSF), access to the 4850 Level and the Davis Cavern was regained. Pumping has lowered the water level to well below the cavern floor. Figure 1 shows the layout and location of the Davis Cavern (Cavity). Detector tank, supporting steel, and so forth were subsequently removed. The cavern was re-supported and new access was developed. By August, 2010, 13,000 ft3 had been removed during enlargement and renovation of the Davis Cavern. Figure 2 shows the detector tank under construction in 1965.

Jan 1, 2012

By Klaus Hasselwander

Fluctuating SO2 gas streams represent a difficult task for designers of SO2 removal systems (with respect to designing the plant), but in spite of the designers great efforts to solve the problems, the operation of such plants requires much care and attention. A fluctuating gas flow usually results from metallurgical smelting processes. Both gas composition and gas flow rate may vary. The first part of this paper outlines some existing technical solutions and presents the Pros and Cons of the different solutions. These solutions outline are: - Sulphuric acid plants operated with a preheater permanent in operation - Sulphuric acid plants with concentration increase of SO2 gas either using regenerative SO2 removal or cryogenic partial condensation of the SO2 - Sulphuric acid plants with additional burning of sulfur to increase SO2 content - Single-stage sulphuric acid plants followed by a tail gas system (which is) designed for periods of low SO2 input In the second part, this paper describes some existing technical solutions for removal of SO2 at low concentrations (i. e. less than 0.1 - 2 %-by volume), which could be used as tail gas treatment system for acid plants. While selecting an appropriate solution, special attention should be given to operating costs, which usually to a large extend depends on the type of absorption agent and the costs for disposal of the sulfur compound produced.

Jan 1, 2009