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By H. -S. Yoon, C. -J. Kim, K. W. Chung

"With the final goal of ultrasonic application to ion exchange in a resin-in-pulp (RIP) system, the feasibility of an indirect ultrasonic application with a submersed ultrasonic probe was investigated first for the enhancement of ion exchange in the following resin-in-solution (RIS) system: Lewatit MonoPlus MP 600XL in an artificial solution with 106 ppm uranium. Ultrasonic radiation enhanced the ion exchange efficiency without mechanical degradation of resin. For 3.6 g/L of resin, the enhancement was 79 percent after 10 min of ion exchange and it gradually decreased to 11 percent at 60 min. In addition, a preliminary test of the mechanical stability of the resin in the RIP system showed little mechanical fracture of the resin due to ultrasound, which indicates that indirect ultrasonic application by a submersed ultrasonic probe is applicable for RIP systems. IntroductionIn uranium ore processing, the ion exchange process has been used on a commercial scale for preconcentration and purification (Gonzalez-Luque and Streat, 1984). The ion exchange process is divided into two processes: (1) a resin-in-column process with the uranium-bearing solutions passed through columns containing resins and (2) a resin-in-pulp (RIP) process with the leached ore pulp exposed to resins. The latter does not require the separation process of leach liquor and ore solids, which reduces process costs. This process, which has been developed commercially since 1955, has a certain drawback. The adsorption rate and efficiency in the RIP process are relatively low, so numerous contacts between resins and leached ore pulp are needed, which adds to the cost (Merritt, 1971). It is necessary to study methods to reduce process costs.Ultrasound can intensify mass transfer, increase the rate of chemical reactions, and change reaction pathways (Thompson and Doraiswamy, 1999; Luque de Castro and Priego-Capotem, 2007; Adewuyi, 2001; Luque-Garcia and Luque de Castro, 2003). It has great potential in chemistry and is especially considered to be a promising method for enhancing mass-transfer-limited processes, such as ion exchange. Enterzari and Tahmasbi (2009) reported the effect of ultrasound on water softening by ion exchange. Band et al. (1997) proposed a modulated ultrasound application to water desalination with ion-exchange hollow fibers. These reports revealed that ion exchange kinetics could be enhanced by the application of ultrasound. As for hydrometallurgy, Feng and Aldrich (2000) reported that the elution of an ion exchange resin was enhanced by the use of ultrasonication."

Jan 1, 2015

By H. Zhao, R. Liao, W. Qin

Theoretically, controlling redox potential to a relatively low value and inhibiting jarosite formation on the chalcopyrite surface would be an effective strategy to accelerate the bioleaching of chalcopyrite. In this work, using limonite as seed crystals, the effects of the goethite precipitation process on the bioleaching of chalcopyrite were studied for the first time. The bioleaching results showed that the addition of limonite controlled the redox potential in an appropriate range and promoted chalcopyrite dissolution through the removal of ferric (Fe3+) ions. X-ray diffraction and scanning electron microscope analyses indicate that limonite significantly induced the goethite precipitation process and inhibited the production of jarosite. We conclude that promoting the goethite precipitation process with limonite is an effective strategy in accelerating the bioleaching process of chalcopyrite.

By Jerry M. Riggsbee, John H. Weber

INTRODUCTION The Washington Metro is a 98 mile rapid transit system that will serve the District of Columbia, southern Maryland, and northern Virginia. The construction work herein described relates to Section B-1 of this system. The contract for this work was awarded by the Owner, The Washington Metropolitan Area Transit Authority, to a joint venture doing business under the name of Ball-Shea-Norair. The partners in this venture were Gordon H. Ball, Inc., Danville, California; J. F. Shea Company, Inc., Walnut Creek, California; and Norair Engineering Corporation, Washington, D. C. The bid price for the project was $33,741,524 with a contract duration of 910 calendar days. Notice to proceed was issued January 5, 1970. The present modified price for the work is $36,866,000 with completion anticipated in July 1974. (About 1,638 days elapsed time.) The work to be done consisted essentially of construction of 3,490 linear feet of cut-and-cover track with side platform, and 600 ft cut-and-cover arch shaped subway stations. Stations are located in Judiciary Square and Eighth & G Street, N. W., areas. Decking of excavation in street areas, maintenance of traffic and utilities, vent and fan shafts, underpinning of court buildings in Judiciary Square and the Smithsonian National Portrait Building, and an electrical substation were included in the contract. Stations were constructed of cast-in-place concrete.

Jan 1, 1974

By G. E. Karantzavelos

Introduction Pure alunite (KAl3 (SO4 )3 (OH)6 ) contains 37% A1203. In the alunite ore found on Milos Island, Greece, opal is the principal gangue while some aluminum, iron, and titanium oxides are also present. Processing of alunite ore leads to the recovery of potassium sulfate, alusil (alumina-silica mixture), and sulfur dioxide. An interesting process has been developed in Greece (Svoronos, 1977) consisting mainly of roasting the alunite ore mixed with KCl to disrupt the mineral lattice in preparation for separating its components. The thermal decomposition of alunite at approximately 600°C occurs by the reaction: KAl3 (SO4)3 (OH)6 + nSiO2 + 6KC1 - 4 K2SO4 + 3 A1203 . nSiO2 + 6 HCl + 3H20 According to the process pure alunite mixed with 543 kg KCl, 840 kg K2SO4, 370 kg alusil, 264 kg HCl, and 65 kg H2O are produced. The roasted calcine is leached in hot water. The potassium sulfate leach slurry is then thickened and washed to obtain a solid residue (alusil) plus a solution rich in potassium sulfate. Assuming the alunite ore feed consists of 50% to 60% alunite, the solid residue might consist of approximately 22% to 27% A1203, silica, iron, and titanium oxides. This leach residue could be digested in a hot sodium hydroxide solution to dissolve alumina. An amount of the alumina (approximately 10%) would not dissolve. In addition, part of the silica would dissolve requiring removal from the solution in a subsequent desilication operation. The same leach residue could be attacked by mineral acids such as a diluted hydrochloric acid to extract aluminum chloride (Sawyer et al., 1983). Alumina and aluminum are presently produced from bauxite of which Greece has important reserves. If this aluminous material (alusil) could be beneficiated by any physical process, then it would be considered as a raw material for the production of fire-clay refractories instead of an alternate source of alumina. Experimental procedure Extensive laboratory work (mineralogical and chemical analyses) indicates that alusil is a mixture of liberated (mostly) alumina and silica particles, not a natural silicate mineral. Table 1 shows the chemical assays of two alusil samples that were obtained from a roasted alunite ore leaching pilot plant. The samples used for the experiments were a very fine alusil powder (K80 = 400 mesh, 38 µm). These were pulped in tap water. Desliming of the pulp before each flotation test was ineffective. Flotation tests were performed in a 2000 ml Denver cell. A standard 500-g sample was first conditioned at a pulp density 50% solids for 5 min with hydrofluoric (HF) acid solution (40%). The temperature of the conditioned pulp was measured and kept nearly constant at 50°C. The pH of the conditioned pulp was also regulated to 2.5-3 with HF solution. Then ARMAC C solution (2%) as well as two drops of fuel oil and one drop of AEROFROTH 65 were added and the pulp was reconditioned for 2 min. After conditioning, the viscous pulp was transfered to the flotation cell. It was then diluted with warm water to about 15% solids and floated to separate silica from alumina particles. A rougher froth product that was cleaned and recleaned was obtained from the flotation tests.

Jan 1, 1987

By William Gleason

"Speakers and attendees of the 2016 Cutting Edge Conference could not be faulted for keeping one eye on the presentations taking place at the Hyatt Regency at LAX in Los Angeles, CA on Nov. 7 and 8 and another on the results of the historic election in the United States that took place on Nov 8. While there was certainly interest in the presidential campaign, there was also a great deal of interest in Measure M on the California ballot. Measure M, which passed easily, is a half-cent sales tax increase that will fund the most ambitious transit expansion in Los Angeles County history.In the coming years, the ballot measure will transform a traffic-choked region by funding the construction of nearly a dozen new rail lines with an estimated $120 billion raised in four decades. Among the projects that could come to fruition are a twin-rail tunnels project through the Sepulveda Pass and new connections in the city.During the update on West Coast projects, Bill Hansmire summed things up with a slide asking “How much work is there on the West Coast,” and his answer was “Billions.”From Seattle, WA south to Los Angeles, there is already a lot of work for tunneling and underground construction experts, and Measure M ensures that there will be plenty of work for decades to come.Currently, The Los Angeles County Metropolitan Transportation Authority (Metro) has three rail projects underway that were funded by Measure R in 2008 — the Regional Connector, the Purple Line subway extension and the Crenshaw/LAX Line that are designed to alleviate the traffic pressure with an eye to more solutions.Measure M is the fourth sales tax increase to fund transportation in L.A. County, bringing the base sales tax rate to 9.25 percent. In some cities, which already levy their own sales tax, the rate would be higher, The Los Angeles Times reported.About 35 percent of the revenue will fund major new transit projects, such as the subway under the Sepulveda Pass, extension of the Gold Line to Claremont, extension of the Crenshaw Line to West Hollywood and acceleration of the Purple Line Subway construction along Wilshire Boulevard to finish in 2024, 10 years earlier than scheduled.About 17 percent would fund a dozen highway improvement projects, such as widening parts of I-5 in the Antelope Valley and southeastern county, adding bus lanes to the Sepulveda Pass section of the 405 freeway and adding truck-only lanes to a section of the 710 freeway."

Dec 1, 2016

By Jack G. Pippenger

The Coteau Properties Co.'s Freedom mine is a surface operation near Beulah, ND that produces more than 13.6 Mt/a (15 million stpy) of lignite. Coteau, a subsidiary of North American Coal Corp., ranks among the largest mines in North America. In 1994, Coteau ranked eighth in annual coal sales, becoming the largest mine outside the Powder River Basin of northeastern Wyoming. However, for the Freedom mine to stand alongside the Powder River Basin heavyweights, Coteau had to overcome several obstacles. These included a coal seam with three-quarters the heating value and overburden-to-coal ratios three times higher than Powder River Basin mines. Coteau's ability to compete has been built around a program of continuous improvements in productivity, cost efficiency and innovation.

Jan 1, 1995

By Donna L. Boreck

Introduction Coal has been mined in the western United States since the mid-1800s. The resource is abundant in the West. Despite recent economic conditions, it remains an important part of the nation's energy warehouse. Many of the seams that comprise the western resource base are thick, some exceeding 61 m (200 ft). Multiple, closely-spaced seams or thick coals that split into two or more minable seams are also common. Historically, subsurface development recovered from less than 15% to 50% of these deposits (Matson and White, 1975). This resulted in a substantial loss of inplace reserve due to the limited height that could be mined using the available technology. In an effort to increase future recovery from such deposits, the US Bureau of Mines analyzed the potential for incorporating three thick-seam mining methods into western coal mines. These methods are high-face longwall, multislice longwall, and longwall caving. They were developed in Europe and are being used to mine thick coal seams in Europe and Asia. One aspect that will determine their success in the US is the geology of the individual deposit; namely, are the methods adaptable to the geologic conditions characteristic of western coal? This paper analyzes some of the geologic factors that would affect development of thick or closely-spaced seams using these mining methods. Occurrence of thick and closely-spaced seams Since mining conditions and methods differ around the world, a thick seam is often defined as a seam whose total thickness cannot be extracted using the available equipment. In the western US, the maximum extractable mining height is about 4.3 m (14 ft). For this research, a thick seam was defined as a minable seam 4.6 m (15 ft) thick or more. Since one of the seams is usually lost using standard mining methods, closely-spaced or split seams were also addressed. These were defined as two minable seams 1.5 m (5 ft) thick or more separated by 9 m (30 ft) of interburden. Thick or closely-spaced coal seams are common in the West. Their importance has not been documented due, in part, to the methods used to measure resources. In the past, all reserves greater than 1.1 m (42 in.) thick for bituminous seams and greater than 3 m (10 ft) thick for subbituminous seams were grouped together and were differentiated only by rank. Further differentiation by seam thickness or minability was not done. For this reason, reserve figures for thick or split seams are difficult to determine. By analyzing available published resource data, Ferm and Muthig (1982) addressed thick seam resources. They estimated a resource of 90 Gt (99 billion st) of coal (16% of the Western resource base) in seams 4.6 (15 ft) or greater at less than 610 m (2000 ft) overburden. Yet, a later study of Pierce and others (1982) on one thick seam deposit in the Powder River Basin estimated a resource of 103 Gt (113 billion st). Pierce (1986) reported that the overburden reached a maximum of 731 m (2400 ft). The resources in this single deposit exceeded the 90 Gt (99 billion st) total projected for the entire western US by 12.7 Gt (14 billion st). Due to such differences, this author chose to look at reported occurrences of thick or closely-spaced minable seams in place of resource figures, to verify the need to research thick seam mining in the West. An occurrence was defined as an isolated site where a thick seam or two or more closely-spaced seams were reported. The occurrences were derived from published material - mostly mine descriptions, measured sections, coal exploration logs, and oil and gas logs. Due to time constraints, the reserves associated with each occurrence were not determined. All data points were random. The analysis was limited to occurrences in Colorado, Wyoming, and Utah. Although source material available to the author was limited to general coal summa-

Jan 3, 1988

By Robert W. Leonardson

The Questa Molybdenite Mine provides a unique opportunity to study the geochemical dispersion of various hydrothermal events, utilizing drill hole analyses. Numerous post-ore factors have altered the primary ore-related geochemical dispersions to the present day configuration, e. g. dikes, faults, hydrothermal convection cells, and weathering. Due to the interaction of an andesitic volcanic pile with the silicic-alkalic generated volatiles, the geochemical haloes of the Goat Hill deposit demonstrate a marked divergence from the classic Climax-type molybdenite ore body. Certainly, however, the similarities to the Climax-type ore body are apparent as potassically-rich fluids have invaded the highly reactive country rock.

Jan 1, 1984

By Vincent R. Bovino

Introduction Only a person fresh from an information vacuum could not know the status of this nation's economy. The inability of the US to compete in the world marketplace is manifested in many industries, from shoes to computer chips, from cars to copper. What industry will next fall prey to world competition? Perhaps the question should be, what insustry will next fall prey to declining productivity? American industry is being forced into an era where the focus must be on productivity, quality, cost control, and competition in the world marketplace. It is approaching a change that could rival the American Industrial Revolution. The future of the US is bright only if it can increase productivity by trying different and new ways to manage its businesses and people. Unlike the easy successes during the 60s and 70s, success in the decades ahead will depend on an ability to compete in the world market. Any operation can achieve unlimited productivity by developing the resources within its employees. As an industry, mining has harvested the earth's resources. As an industry in trouble, it now has to learn to tap human resources to release the energy and creativity in each person. Recently, I worked with a mining operation to reopen a mine and implement a different management approach. The extensive changes resulted in a 50% reduction in cash cost of producing silver (from $0.40 to $0.19/g or from $12.50 to $6 per oz). Thus, an unprofitable mine became an attractive business venture without technological changes or significant capital infusion. The operation is union-free, in spite of being in a highly unionized area. The mine implemented a real productivity improvement process called "gain-sharing." Employees now recognize their individual success is tied to the success of the business. They recognize the day of the free lunch is over for mining employees. This paper will explore three areas related to productivity: • some of the unspoken "whys" of the mining industry's paralysis and how management has caused unproductiveness in mining operations; • major components of a productivity improvement process; and • characteristics common to companies with successful productivity plans. Unspoken whys When things go wrong, everyone tends to point a finger at someone, anyone. This industry has blamed every conceivable person, corporate group, government agency, foreign government, and private group for its failures. The fault finger will not work anymore. Nobody is listening. It is a characteristic of winners in management to assume responsibility for less than acceptable performance. Excellent people tend to blame others less for problems. Everyone involved in mining should shoulder part of the blame for the industry's illness. Is the problem low prices or our high operating costs? To regain our status in the world marketplace and increase our productivity, we need to painfully and honestly talk about our mistakes.

Jan 3, 1986

By John F. Clarkson

White Pine Copper Company built and operated, from August, 1962 through May, 1963, a pilot plant to recover copper using a cyanide percolation leach of the sand fraction (+400 mesh) of the mill tailings (1, 2, 3). The pilot plant runs were metallurgically successful and preliminary engineering studies for a full scale operation were completed under contract by an outside engineering firm. Unfortunately, the net return projected at that time did not justify the proposed capital' investment. In the summer of 1973 the project was revived. The rise in selling price of copper over the previous ten years, compared to the projected operating cost of the leach plant, increased the calculated net return on investment with the most recent figures showing a 30% DCF. Basically, the reason for this favorable shift in profitability was that the cost for many of the reagents did not go up as fast in the previous ten years as did the selling price of copper. Using the Chemical Marketing Reporter costs, NaCN sold for 18.3¢/lb in 1963 and 20.75¢/lb in August, 1973. During this same period H2S04 went from $23.50 per ton to $35.90 per ton. In comparison, producer's prices for electrolytic copper were 31¢/lb in 1963 and 619 in 1973. Thus the price of copper went up 97% while the two reagents only increased 13% and 53%, respectively. The capital investment also escalated but, again, not to the same extent as the selling price of copper. These price differences no longer are valid' but they did provide justification for reexamining the project.

Jan 1, 1975

By John L. Stafford

The ROEMMC combustion system was originally conceived as a means of utilizing solid fuels that would otherwise have been wastes requiring disposal and convert these fuels into useful energy sources. This concept follows as an extension of the application of residual waste incineration with energy recovery practiced in the lumber, manufactured board, sugar cane, and other industries. The incineration of these wastes in the furnaces of steam generating equipment is thoroughly described (1, 2, 3, 4, 5, 6, 7). The fundamental principle of the ROEMMC system is temperature control which makes possible the maintenance of the non-combustible fraction of these solid fuels in a dry solid state and their separation from the gaseous products of combustion. This philosophy of ash removal and the "slagging" philosophy are compared. The ROEMMC equipment function and applications are described.

Jan 1, 1978

By B. Li

"Sepiolite is a magnesium-rich, porous, and fibrous clay mineral with broad applications. These applications take advantage of sepiolite’s high specific surface area and unique nano-sized channel structure. Over the past years, numerous materials and techniques based on the structure and property of sepiolite have been developed. This article reviewed the recent achievements in developments and applications of sepiolite in environmental protection, catalysis area, and nanocomposites. The prospectives of sepiolite applications is also discussed. INTRODUCTION Sepiolite is a magnesium-rich, porous, and fibrous clay mineral. The typical chemical formula of sepiolite is Si12Mg8O30[OH]4[OH2]4·8H2O [1]. Sepiolite has a high specific surface area and nano-sized channels because of its special structure [2]. This unusual crystal structure projected onto the [001] plane is shown in Fig.1 [3]. As it can be seen, silicon and oxygen atoms make up for the tetrahedral structure and magnesium and oxygen atoms form octahedral structure, respectively. Those tetrahedral-octahedral-tetrahedral ribbons expand boundlessly in one direction, leading to the special fibrous structure of the sepiolite. Every tetrahedral-octahedral-tetrahedral ribbon is combined to the next by an inverted Si–O–Si bond, which causes an interlaced layer with a continuous tetrahedral sheet and a discontinuous octahedral sheet. Terminal MgO at the edges of the ribbons is coordinated with two structural water molecules, which can form hydrogen bonds with zeolitic water molecules that are located in the channels running parallel to the fiber axis [3,4]. The Mg2+ ions inside the channels can be exchanged with other cations in solution. Therefore, sepiolite can be used to remove metal cations from aqueous solutions [5,6].It can be seen from Figure. 1 and Table 1 [7], the unique structure endows sepiolite with a substantial surface area and nanoscale channels. Its specific surface area reaches 320 m2/g and channel dimensions up to 3.7×10.6 Å. There are three active adsorption sites on the surface of sepiolite: one is oxygen atoms of the Si-O tetrahedron. The second is the structural water molecules paired with magnesium ions at the edges of the ribbons, which can form hydrogen bond with adsorbent. The last one is the Si-OH groups due to the breaks of the Si-O-Si bonds on the surface of Si-O tetrahedron. Thus, sepiolite has strong adsorption ability which has been widely used in environmental protection. Moreover, sepiolite has many significant features such as good mechanical and thermal stability, rheological property, porous, and easily modification, making it be a hotspot in chemical and biological researches. However, with the development of technology, broader and more advanced applications of sepiolite have been carried out in recent years. In this study, the recent achievement in sepiolite applications is summarized, the further tendency is also discussed."

Jan 1, 2018

By William L. Carter

Through your presence here this morning and your membership in the Society of Mining Engineers, you have shown that you are interested in keeping abreast of the latest technology and mining procedures, want to be part of the continuing progress made by those in your profession, and are looking for ways to participate in expanding your professional and personal experiences and skills. All of these factors are part of your continuing education, the need for peer identification or recognition, and the desire to make a specific contribution to strengthening your profession. However, you may be here with or without your company support and financial backing, unless you are self-employed. Whether you are here for the above reasons, or for many others, your presence reflects a recognition of the importance of participating in the organizational structure of your profession.

Jan 1, 1981

By L. W. Teal

The Paupers Dream Property is located in the northern Boulder Mountains, southwestern Montana, 30 km southwest of Helena. The property is situated in the central portion of the Butte-Helena gold belt, a NE trending lineament marking a zone of recurrent, late-Cretaceous to mid-Tertiary volcanic activity. Geology consists of a plutonic basement of late-Cretaceous quartz monzonite overlain by a pre-volcanic basal conglomerate and a complex sequence of Oligocene rhyolitic volcanics. Gold mineralization occurs in fracture-controlled quartz veins, silicified stockwork, and brecciated shear zones as auriferous pyrite, arsenopyrite, and disseminated free gold. An estimated 60,000 tonnes averaging 2.5 g/t was produced from the Porphyry Dike, Venus, and Paupers Dream Mines on the property. Current drill indicated reserves (May, 19861 are placed at 6,946,000 tonnes averaging 1.45 g/t gold.

Jan 1, 1987

By U. Schoepf

Economic and at the same time environmentally acceptable mining of small vertical ore bodies and veins to great depths has always been a challenge for miners. The Bauer cutter system, widely used in civil engineering, has been further developed for applications in exploration and mining, to a sustainable system for selective mining with a focus on small vertical ore bodies and veins, as well as residual ore in open pit operations. Current situation of conventional mining of small ore bodies and vertical veins Small ore bodies and vertical or near-vertical ore veins often pose a challenge to the mining industry. The relatively small size of the ore deposit over great depths or lengths, with only limited exposure to the surface makes economical mining difficult. Open pit mining of such ore bodies must either be terminated early because of the high stripping ratio and the enormous environmental impact or is unprofitable from the very beginning. The required massive stripping of waste rock leads to high material hauling times and costs, intensive roadway and bench construction and maintenance, possible safety hazards due to heavy vehicle movement, pit wall stability risks, intensive surface water management and massive waste dump requirements. In addition, it can be assumed that increasingly extensive rehabilitation measures will be required in the future after mine closure. Particularly in vertically oriented magmatic and hydrothermal deposits the technical, economic and environmental limits for further pushbacks, to extend the open pit depth, can lead to an early end of mine life even if a significant quantity of residual ore is left behind. Going underground is only a viable option in a limited number of mines with very high ore values and volumes. The high development cost of an underground mine, as well as the higher underground mining costs, often prevent further mining to greater depths.

Feb 1, 2023

By B. R. Waples

The first reaction in organizing a project of magnitude is that it's the same as smaller projects -- just bigger. This is not totally correct. The industry's record of completing big-money jobs on time and within budget is not outstanding. From a personal point of view, my question is: What is the project size at which controls are lost? Is it controls? Is it the number of pieces of equipment? Is it the number of decisions to be made? The slowness of communications? Or is it a combination of all of these? In working on multimillion-dollar jobs, the percentage of overrun seems to be lower or show an underrun when the following basics are followed: 1) Preplanning is intensified 2) Data gathering is complete 3) Approach is optimized 4) Planning is realistically scheduled 5) Changes are minimized 6) Decisions are expedited

Jan 1, 1982

By R. D. Rein

The Henderson mine is a large continuous panel caving operation in central Colorado. The orebody is roughly 760 m by 910 m and will be extracted from two production levels. Each level is divided into three north - south panels 244 m to 317 m wide. The general arrangement of a production level and its associated undercut drifts is shown in Figure 1. The production drifts (3.6 m by 3.7 m) are spaced 24 m apart center to center and have undercut drifts (3.4 m by 3.8 m) 17 m directly above them. The production drifts are interconnected with drawpoint crosscuts (4 m by 4.3 m) driven on 12 m centers. Drawpoint crosscuts receive substantial brow steel and concrete support prior to undercutting. The brow steel is a 15 cm by 46 cm wide flange beam with a 2.5 cm wear plate to box in the 'cave' side of the beam. The concrete is a minimum of 0.3 m thick and the batch design results in 27 500 kPa strength. The finished drawpoint opening is 3.7 m by 3.2 m with a choke area of 3.7 m by 2.4 m. (Figure la) Undercutting and bell formation is accomplished by blasting rings of 7.6 cm holes drilled from the undercut drifts. The rings have a burden of 2.0 m and six rings develop one complete bell.

Jan 1, 1985

By Donna Wallace

Past EPA groundwater monitoring programs required that contamination not leave the boundaries of a disposal facility. New regulations under the Resource Conservation and Recovery Act (RCRA) require that once hazardous waste constituents are detected beyond the limits of the disposal area, a program to define the rate and extent of contaminant migration must be instituted. Future regulations are likely to include even more stringent groundwater protection criteria. The implications of both the existing and probable future groundwater protection and monitoring requirements in terms of using geologic containment as a means of disposing of hazardous waste are explored in this paper.

Jan 1, 1981

By H. Sevim

Placement of coal combustion byproducts into abandoned sections of underground coal mines for the purpose of subsidence mitigation has been investigated in Illinois. Several handling and transportation systems have been examined. Prototype pneumatic and hydraulic placement systems have been developed and demonstrated. The demonstration site, Peabody No. 10 mine in Pawnee Illinois, is selected as a case study. It is found that, for a project of 5 years, transporting 150,000 tons of byproduct annually from a power plant located 32 km (20 miles) to the mine would cost $1.80 per ton and placement into underground would cost $3.07 per ton.

Jan 1, 1998

By Clay Haynes, Tim Pearia, Robert Robinson, Judy Cochran

A 1.89 km-long, 4.5 m-I.D. tunnel was successfully constructed through saturated hard clay, and highly abrasive dense sand and gravel, with groundwater heads ranging from 10 to 20 m. In order to address these conditions, a Lovat earth pressure balance TBM was used, with soil conditioning by foam, water and various polymers. Support was provided by a single-pass segmented concrete lining. Groundwater inflows of 400to 1,600 lpm at times created challenges for changing cutting tools. Surface settlements were generally less than measurement thresholds, except under very low cover at startup. This project provides a pivotal case study of the successful application of EPBM technology in saturated, abrasive glacial soils and the successful application of soil conditioners.

Jan 1, 2003