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By James E. Monsees

Extensive underground excavation will be required for construction of a mined geologic repository for nuclear waste. Hundreds of thousands of feet of drift will be required based on the conceptual layout design for each candidate nuclear waste repository. Comparison of boring and blasting excavation methods are discussed, as are special design and construction requirements (e.g., quality assurance procedures and performance assessment) for the nuclear waste repository. Comparisons are made between boring and blasting construction methods for the repository designs proposed for salt, volcanic tuff, and basalt. Differences in the geologic media and settings of the prospective sites influence the excavation method in terms of drift length, size of opening, drift slope, rock quality, and boreability. Support requirements, ventilation, and the ability of the geologic system to retard radionuclide migration are also directly impacted by the geology and excavation method.

Jan 1, 1987

By R. R. Oder

Reported are weight, particle size, gross chemistry and magnetism measurements for lithic, mineral and fused soil components separated from five lunar soils using dry, open-gradient, magnetic separation. Pure diamagnetic anorthite, a feedstock for the electrochemical separation of oxygen and metals, has been separated from anorthistic highland soils. In addition, paramagnetic ilmenite has been separated from high-titanium, basaltic mare soils. Ilmenite, a feedstock for oxygen preparation by hydrogen reduction, may also serve as a source of He3 for use in fusion power generation. Agglutinates (vesicular, glassy components containing metallic iron) have been separated from all of the soils. Iron and refractories can be used for space construction. Metallic iron is easily detected in lunar soils by magnetic susceptibility measurements. Based on the exploratory laboratory results, conceptualizations of innovative magnets for processing lunar soils are presented.

Jan 1, 1993

By Harold Stocker

INTRODUCTION This presentation is concerned with the administrative and technical capability of the Atomic Energy Control Board (AECB) to assure compliance with the individual exposure limit for radon daughters (currently 4 WLM per year). It is not concerned with the epidemiological bases for setting the exposure limit. Moreover, the intent is to show how sophisticated methodologies and advanced technologies, applied to radon daughter concentration measurements in uranium mines, convey the spirit of compliance by providing better estimates than do the historical methods. These better estimates mean that more accurate and more precise estimates of each worker's exposure are determined using these more modern methods and devices. The estimates so derived should provide more convincing evidence to an individual worker that his assigned exposure is a valid indicator of his true exposure. In addition, a perspective on the exposure estimate in relation to the exposure limit is given as further evidence that an exposure limit is not the dividing line between "safe" and "unsafe" exposures. A brief description is given of the compliance aspects of the Atomic Energy Control Regulations and of the limitations of purely statistical non-compliance procedures. Most of the emphasis of the paper will be placed on the uncertainties associated with conventional radon daughter exposure determination and the means being employed (and anticipated) to reduce these uncertainties. NON-COMPLIANCE Under current Atomic Energy Control Regulations (1978), the annual individual exposure limit for radon daughters is given without reference to the possible methods of sampling and calculation of radon daughter exposure and without any reference to possible uncertainties or their magnitudes. This is common in such statutes, the details of sampling, calculation, error analysis, and so on, being left for licence conditions or provided as a specific guideline to the licensee on the matter of compliance with the Regulation. Since the exposure limit is contained in the Regulations, compliance with it is absolute, as with any other law. In Canada, a state of non-compliance with the radon daughter exposure limit exists when an exposure (attributed to an employee) is reported by the licensee to exceed the limit. No uncertainty in the measurements or in the overall determination of exposure is reported nor is any requested. Removal of the worker and the loss of his services are the immediate and direct penalty suffered by the licensee for failure to maintain the exposure at, or below, the limit. A worker may be re-instated to employment for the balance of the reporting period only if the licensee can assure the AECB that further significant exposure to the worker will not ensue. In other jurisdictions, such as the United States, non-compliance is defined on a statistical basis. For example, NIOSH, the National Institute for Occupational Safety and Health presents procedures for calculating the 95% Lower Confidence Limit (LCL) in order to "compare the results of occupational environmental sampling to an occupational health standard and make a decision with a known chance of making an incorrect decision that a state of non-compliance exists" (Leidel and Busch, 1975). (In the nomenclature of this presentation, exposure limit would be used in place of "standard", in the NIOSH sense). Furthermore, it is emphasized in the NIOSH document that such numerical comparisons "are necessary only if the sample mean is greater than the standard". The NIOSH document points out, quite correctly, that the "statistical procedures presented below will not detect and do not allow for analysis of highly inaccurate results, i.e., systematic (non-random) errors or mistakes ... If a systematic error is known to exist in an instrument or analytical procedure then correct the sample mean of the data before analyzing for non-compliance". It is certainly not the purpose of this paper to criticize the sophisticated statistical approach to non-compliance as given in the NIOSH document or in similar approaches used in other jurisdictions. Rather, the purpose is to approach, with some introspection, the question of the determination of exposure by the employer for his employee and especially the employee's understanding of, and confidence in, the accuracy of the exposure determination and its relation to the exposure limit. DETERMINATION OF EXPOSURE Historically, in uranium mines, exposure to radon daughters for an individual miner

Jan 1, 1981

By E. O. Mixon, Joseph P. Sehulster

This paper describes the driving of a 1421 m long by 2.74 m diameter sewer tunnel in postglacial soils of the Menomonee River Valley in Milwaukee, Wisconsin. An earth pressure balance machine was used for excavation and to install a "one pass" pre-cast concrete gasketed segmental liner. Also discussed is the use of ground freezing to stabilize the ground for the start of tunneling operations and modifications made to two structures to accommodate final tie-ins for the sewer tunnel.

Jan 1, 1989

By Clement K. Chase, George M. Potter

Copper dump and heap leaching operations are conducted worldwide for production of substantial amounts of copper Such dumps and heaps contain appreciable amounts of other potentially valuable elements such as gold, Iron, magnesium, manganese, molybdenum, silver, titanium, and uranium. Except for uranium, recovery of these elements has not been attempted to any significant extent However, such recovery merits attention based upon availability of existing chemical techniques. This paper presents some thoughts on possible techniques together with opportunities for commercial applications.

Jan 1, 1983

By W. G. Pariseau, S. C. Schmelter

The destabilizing effect of water pressure on rock-mass stability is examined quantitatively by the finite element method. A coupled code that accounts for the simultaneous effects of rock-mass deformation and transient fluid flow is used for this purpose. The traditional soil-mechanics assumption of an incompressible fluid is shown to be untenable for the analysis of porous, fractured rock slopes. A Mandel-Cryer effect, whish is a transitory but elevated and potentially destabilizing water pressure following a cut, was not observed.

Jan 1, 1999

By L. Berwick, A. Karunanayake, D. Skutt, H. Heath, J. Wang

Thallium (Tl) is a highly toxic heavy metal, soluble over a wide pH range. Tl levels may exceed discharge limits in mining-influenced water associated with processing gold, lead, cadmium, zinc, and copper ores. In this work, the effect of sodium permanganate (CARUSOL® C liquid permanganate) on Tl removal from mining wastewater was studied. Factors influencing Tl removal, namely permanganate dosage/demand, coagulant and flocculant use, order of chemical addition, and co-existing metal ions were examined. The results show that permanganate addition is very effective at removing Tl to below target limits and can provide a unique solution for improving wastewater quality and optimizing overall treatment costs. In addition, several on-line monitoring techniques were evaluated for process optimization. The Hach DPD Free Chlorine method was optimal, allowing plant operators to rapidly and easily spot check effluent samples for excess permanganate dose.

Mar 2, 2022

By E. G. Williams

Underclays and shales are two natural resources associated with the coal measures. Underclays are widely used as the raw material for refractory, semi-refractory, and face bricks. Shales are useful for sewer pipe and lightweight aggregate. This study concentrates on the geologic controls over the properties of shales for use in the manufacture of lightweight aggregate, and the geologic controls over the properties of underclays for use in the manufacture of bloating ladle refractories. The industrial processes are similar in that both involve the trapping of a gas phase to cause bloating. They differ in that the bloating of lightweight aggregate occurs at lower temperatures (1000-1200°C) than ladle bricks (1350°-1470°C). Lightweight aggregate bloats during an initial rapid firing. Ladle bricks are manufactured by slow firing at 1100°C for up to 80 hours. Bloating occurs when these bricks are reheated to 1350°C . Bloating shales are those which expand twice or more times their original volume during fairly rapid firing. Commercial bloating is usually done by rotary kiln processing or sintering; in both cases the firing rate is much faster than the experimental rate (5/8°C/minute). Bloating results from the entrapment of gasses which are evolved during firing. The material must have adequate viscosity to trap gas bubbles throughout the temperature range of bloating. The finished product contains a high percentage of closed pores with a bulk density between 35-75 pounds per cubic foot. Expanded shale finds its most important use as a substitute for heavy concrete aggregate (crushed stone, sand and gravel) where low bulk density is desired property. The extent of bloating in lightweight aggregate is a function of the mineralogy and chemistry of the shale. Figure 1 shows a corner of the three phase diagram, kaolinite-quartz-(illite and chlorite). Several areas on the diagram are outlined which contain predominantly marine shales, fresh and brackish water shales, and underclays. Each sample was rapid fired and the resulting expansion was plotted on the phase diagram.

Jan 1, 1973

By A. Wahab Khair

There are a number of factors, including mine geometry, local geology, geotechnical properties of overburden materials, surface topography, sequence of overburden strata, and extraction rate, affecting characteristics of surface subsidence imposed by large underground excavation. Among the factors, the first three have the major impact on magnitude and area of influence of final subsidence. Hence, a model has been developed, considering mine geometry and geologic and geotechnical properties of the associated area, to predict maximum possible subsidence and subsidence profile at any cross-section within the subsidence influence zone. Based on extensive field measurements and mechanics of strata behavior, under the action of overburden pressure in the vicinity of the large underground excavation, the vertical plane of influence zone has been divided into five areas: 1) excavated, 2) caved, 3) fractured, 4) highly deformed but continuous, and 5) subsided zones. In the final state of subsidence each area maintains a certain volume expansion/contraction, i.e. a factor which depends on geologic, geotechnical properties of overburden strata and state of stress within the subsidence trough. The cumulative volume expansion and contraction partially compensates for the extracted volume and the difference between the two is reflected as the subsided area in the form of the area within a curve defined by a probability function. The input parameters for the model are mine geometry (i.e. length and width of the panel), depth of cover, and geologic and geotechnical properties of overburden strata (i.e. percentage of hardrock, sandstone and limestone, and soft rock, shale within the overburden strata and Rock Quality Designation). The model calculates angle of draw for the site, expansion factor for each zone utilizing empirical relationships, maximum possible subsidence and plots the subsidence profile curve. The model is developed for a longwall excavation with unique characteristics of prediction of angle of draw and maximum possible subsidence for a given geologic and mining condition at any cross-section within the influence zone of subsidence.

Jan 1, 1986

By George L. Baloo, Dave Kwiatkowski, Jose G. Cañlzales

Capital project funding for a medium to large materials handling project often includes a budget for procurement of supplier-recommended spare parts, and it is the Project Team's responsibility to select these parts. With today's economic climate, limited budget, and other factors, the spare parts selection process is a difficult and arduous effort. This decision carries with it a risk to plant operations and in some cases the commodities producers. Too often the decision-making process is not documented, and the reasons for eliminating and reducing quantities are based on "best guess " Recently on the Solids Handling Phase 2 Project in Jose, Venezuela, the Project Team took a unique approach to this problem. This paper discusses the analytical approach taken by the Project Team, the database system that was developed to manage this problem, lessons learned, and their applicability to pre- project planning and preliminary design.

Jan 1, 2004

By D. C. Torre

The coal mining industry has long recognized the need for a system capable of hauling mined coal from the face in a continuous flow. More than 30 years ago, successfully operating continuous haulage systems were first placed in the field. There were a few individually successful applications. However, the truly successful use of such systems really only began in the early seventies. Today, a variety of systems are available from a number of manufacturers. Even so, continuous haulage has not achieved the acceptance and application it would seem to have earned. There is a need for more productive, cost-effective, and safer methods of hauling coal from the face. There is also a need to speed up development for longwall operations. And continuous mining is not really "continuous" unless it is supported by a reliable continuous haulage system. Despite all this, most of the coal producers have failed to exploit the successful continuous haulage systems offered by several manufacturers. In the 1970s, many of the top coal producers tried a continuous haulage system but gave up on it and on the concept. In some cases, major coal companies had systems operating successfully in one mine, or even one division. But their use did not spread to others of their mines or divisions. Frequently, their use was eventually abandoned, even in mines where it had been successful.

Jan 1, 1990

By D. S. Young

The random variable transformation technique was introduced to make probabilistic structural analysis simple for such structures as slopes, dams, foundations, or retaining walls, where two shear strength parameters are required to analyze their stability by deterministic engineering methods. The Gaussian transformation was performed by using the Hermite orthogonal polynomial function. This transforms the experimental histogram into the standard normal distribution, whose mean is zero with a variance of one. Then, the transformed standard Gaussian variable was used for the bivariate normal probability analysis on the structure. The Gaussian transformation technique and the Hermite polynomial functions were chosen because the bivariate joint normal distribution is well-known and easily available for engineers. The binormal probability analysis was made on the probability region of a certain confidence level by superposing the critical line on the same probability region that divides the region into two zones: stable and unstable zones. The critical line was determined from the back calculation of the deterministic engineering method of the structural design. Finally, the probability of structural failure at a desired confidence level was calculated by simply integrating the volume of the binormal density surface above the unstable zone in the probability region. A simple case of slope analysis is introduced to illustrate this probabilistic approach, and its effectiveness and simplicity is demonstrated.

Jan 1, 1987

By Davidtz. John C.

INTRODUCTION The effectiveness of collector type on sulfide mineral flotation is generally determined by the amount and type of functional groups of collector molecules that interact with surface and water at the mineral/collector/water/gas interface. The final interfacial state when bubble contact takes place is preceded by chemical and physical reactions that involve these gas/liquid/solid interactions. These interactions differ not only for different minerals, solution and gas composition, but also for different collector molecules. The purpose of this paper is primarily to summarize the developments and status of short (C2-C6) and long (C12) chain, aliphatic collectors that contain three sulfur atoms in their polar function. These are trithiocarbonates (TT'Cs). For purposes of comparison, similarities in molecules containing 0, N and S are compared. Mostly short chain ionic collectors molecules of dithiocarbonates (DTCs) and TT'Cs were compared. The studies, largely bench scale flotation and plant testing, were carried out on ores containing Cu, Ni, Au, and PGM's. Studies of long chain 'ITC collectors are reported on Ni, PGM and auriferous pyrite ores containing uranium. Under starvation dosage conditions, surface activity coefficients of short chain collector molecules and interacting water were calculated. Based on the UNIFAC group contribution method of activity coefficient calculations, the Gibbs Excess Free Energy

Jan 1, 2005

By Nora M. Hutt, Kevin A. Morin

The Sobek humidity cell has been in use with minor modification for more than 30 years to determine bulk primary-mineral reaction rates. As a result, it has become a key tool for predicting the bulk rate of sulphide oxidation, the Carbonate Mole Ratio (CMR) of neutralization-potential (NP) consumption to sulphide oxidation, and the rates of metal leaching. Most humidity cells are operated for less than a year, with the resulting rates extrapolated into the future for years or decades. The validity of these extrapolations was tested by examining longer trends from cells that have operated for three to seven years, as found in the International Kinetic Database (IKD). Additionally, large batches of cells for two minesites in the IKD (45 and 46 cells each) were examined to determine if regular, predictable trends were obtained across ranges of geochemistry at a minesite. The long-term cells show that the rates of sulphide oxidation and acid generation, based on sulphate production, have a 50% chance of stabilizing within one year, with the remainder fluctuating significantly throughout their test periods. Despite the fluctuations, the CMR, which is critical for defining site-specific or rock-unit-specific ABA criteria, remains relatively steady in many cases between 1.0 and 2.0 as expected from principles of aqueous geochemistry. However, if the sulphate-production rate falls below 10-30 mg/kg/wk, the CMR value can increase significantly. At and below these low rates, physical factors like flow rates of surface waters and groundwaters will determine the rate of NP consumption, rather than geochemical factors. Also, if weekly rinse pH falls to acidic values, the CMR will decrease below 1 .O, reflecting the exhaustion of fast- neutralizing minerals. The two batches of multiple cells also confirm these trends across arange of geochemistry. The long-term cells show that copper leaching often stabilizes within a narrow range as long as rinse pH remains relatively constant. Also, there is no strong dependence of leaching on the sulphate rate. However, the rate of copper production often increases sharply if rinse pH falls to acidic values. This suggests the measured copper-production rate in some cases is not a true primary rate, but a lower secondary rate after secondary- mineral precipitation within Sobek cells. As with the long-term cells, the batches of multiple cells show that copper production often increases gradually with decreasing rinse pH, with no clear dependence on sulphate production. However, high rates can also occur at near-neutral pH, so secondary-mineral precipitation of copper is not necessarily common.

Jan 1, 2000

By B Scheiner, D. A. Stanley

Introduction Treatment of ores to recover metal and mineral values results in waste materials usually in the form of dilute slurries. The US Bureau of Mines (USBM) investigated a technique for dewatering phosphatic clay waste by flocculating with polyethylene oxide (PEO) and dewatering the resulting floes on a static screen and/or trommel screen (Schemer et al., 1985). In the investigation, it was determined that PEO was far superior to polyacrylamide polymers for this type of dewatering. This paper discusses reasons for this superior performance. Comparison of PEO with polyacrylamides Dewatering experiments were conducted by adding PEO solution from a burette to a stirred clay slurry. The dewatering endpoint was characterized by rotation of the floc mass as a unit, a clear supernate, a maximum floc size, and a minimum floc volume. Additional water was removed from the floes by hand squeezing (Schemer et al., 1985). The clays investigated were sodium, potassium, magnesium, calcium, and aluminum exchanged montmorillonite and attapulgite. Nine commercially available (Superfloc) polyacrylamides were compared with PEO at two polymer concentrations. Results are summarized in Table 1. The solids content of the dewatered clays ranged between 24% and 33% and was highest for PEO-treated material. These results and the data in Table 1 indicate that PEO is superior to polyacrylamide in terms of polymer dosage required. Superflocs 16 through 128, like PEO, are nonionic and should give similar results to those for PEO if the flocculation mechanism is the same for both type polymers. Superflocs 204 through 214 are anionic with increasing anionic character from 204 to 214. Generally, the anionic polymers gave the best results for the polyacrylamides tested, but in terms of dosage they were not as good as PEO. Correlation between flocculation and dewaterability of waste slurries The overall mechanism for mechanically induced clay dewatering is not completely known, but certain observations can be made. For instance, when a polymer is adsorbed on a clay such as montmorillonite, the polymer desorbs interlayer water. Polymer adsorption is driven by favorable entropy changes associated with this water desorption. It is also known that the -CH2-CH2- links of the PEO chain are sufficiently hydrophobic to lead to physical adsorption of the polymer (Theng, 1979). For montmorillonite slurries, the sheet-like fundamental particles, called tactoids, consist of a small, variable number of aluminosilicate layers together with interlayer water and exchange ions. The flocculation process consists of adsorption of polymer on the tactoid. Loops and tails of polymer that extend into solution then adsorb on another tactoid, forming a bridge. Mechanical action, induced by hand squeezing or in a trammel, joins the bridged tactoids face-to-face and edge-to-edge to form regions of high density. Similar orientation effects are observed for the needle-like attapulgite crystals (Schemer et al., 1985). Proposed flocculation model Generally, statements concerning flocculation and dewaterability apply to both PEO and the polyacrylamides. However, PEO has additional interaction with the clay material when compared with polyacrylamides. PEO is a polymer with repeating -CH2-CH2-O- groups and interacts with montmorillonite through a water bridge whose strength is greatly influenced by the exchange ion. To obtain insight into this interaction, a series of experiments were conducted in which different ion exchange forms of montmorillonite and attapulgite clays

Jan 1, 1987

By G. C. Van Bever, J. J. Zaluski

Introduction The Surface Mining Control and Reclamation Act (Public Law 9587) (hereinafter the "Act" or "SMCRA") passed by Congress in August 1977 represents a comprehensive federal scheme for controlling surface coal mining and the surface effects of underground mining through permitting requirements, performance guidelines and reclamation planning. While the provisions of the Act have been the subject of numerous legal challenges and court battles over the years, it is difficult to identify a more controversial program within the Act than the provisions for designating lands as unsuitable for surface coal mining operations. The lands unsuitable designation process provides for the acceptance and review of petitions submitted by citizens or organizations seeking to have specified land areas designated unsuitable for all or certain types of surface coal mining activities. In filing these petitions, the interested parties or petitioners are required to make allegations about potential adverse impacts on people or the environment and submit evidence supporting their allegations. In 30 U.S.C. § 1272, Congress provided that "[a]ny person having an interest which is or may be adversely affected shall have the right to petition ... to have an area designated as unsuitable for surface coal mining operations." Under the Act, an area can be designated as unsuitable where the mining operation will (1) be incompatible with existing state or local land use plans, (2) affect fragile or historic lands, (3) affect renewable resource lands where mining operations could result in substantial loss or reduction of long-range productivity, or (4) affect natural hazard lands where such operations could substantially endanger life and property. In enacting SMCRA, Congress mandated that each state establish a process to determine which, if any, lands within the state are unsuitable for all or certain types of surface mining operations. In response to this federal legislation, the Kentucky General Assembly adopted a state regulatory program for surface mining that included provisions direct¬ing the Secretary of the Natural Resources and Environmental Protection Cabinet to establish a program for designating lands as unsuitable for surface mining as required by the Act. In recent litigation in Kentucky, several environmental groups filed a lands unsuitable petition, later joined by the University of Kentucky, challenging a proposal by Arch Mineral Corporation to surface mine over 3 million tons of recoverable coal. The petition sought to designate over 10,000 acres of land adjacent to Arch's proposed operations as unsuitable for surface mining operations, basically alleging that the mining would disturb an outdoor laboratory. The filing of the petition activated Kentucky's regulatory scheme for reviewing lands unsuitable petitions that can result in an absolute prohibition against surface mining on the petitioned land for historical, environmental and other related reasons. The designation process involves vague petition requirements creating a situation that Arch argued is devoid of constitutional due process and subject to abuse by the petitioner on many fronts. Arch maintained that the lands unsuitable regulations do not grant adequate protection to Arch's legitimate property rights under the due process clauses of the United States and Kentucky Constitutions and are thus void and unenforceable. The entire process resulting in a decision on the petition took just under 12 months in the Arch case, and although Arch was ultimately successful in preserving its right to mine, Arch's surface mining permit was held up for this period of time. This delay led to the cessation of mining operations by Arch and the idling of over 250 workers. This paper will review the lands unsuitable designation process and the significant implications the process has for existing surface mining operations, currently proposed operations and even those long-range operations not yet contemplated. Special emphasis will be given to Kentucky's lands unsuitable program. Finally, the recent litigation involving Arch Mineral Corporation and its effort to surface mine 81.5 acres of Arch controlled property will be utilized to illustrate this very unusual regulatory scheme. Regulatory background Chapter 30, Subchapter F of the Code of Federal Regulations (C.F.R.) promulgated to implement the provisions of SMCRA, requires that each state establish procedures under the state's surface mining program for designating non-federal and non-Indian state lands as unsuitable for all or certain types of surface coal mining operations. 30 C.F.R. § 764.1. The C.F.R. establishes minimum standards for state lands unsuitable programs and sets out requirements for filing a Lands Unsuitable Petition (hereinafter "LUP"), processing LUPs, decision-making guidelines and hearing requirements. Kentucky has adopted regulations providing for the implementation of the lands unsuitable process as part of the state's regulatory program under SMCRA. The following discussion summarizes the principle components of the Kentucky lands unsuitable program.

Jan 1, 1993

By G. Pierson

Explanations for commodity price levels (or movements) commonly focus on the fundamentals of supply and demand otherwise they are simply assigned to speculative activity. Comparisons of metal-price histories to monetary and other economic data support the argument that the supply of and demand for money are no less important in the determination of price than are the supply and demand of the commodity itself. That these relationships should exist is evident in the price identity and they are consistent with monetary theory. The patterns developed have limited usefulness as predictors, but their recognition is essential for the construction of price scenarios for planning purposes.

Jan 1, 1998

By G. Pierson

Explanations for commodity price levels (or movements) commonly focus on the fundamentals of supply and demand, otherwise they are simply assigned to speculative activity. Comparisons of metal-price histories to monetary and other economic data support the argument that the supply of and demand for money are no less important in the determination of price than are the supply and demand of the commodity itself. That these relationships should exist is evident in the price identity and they are consistent with monetary theory. The patterns developed have limited usefulness as predictors, but their recognition is essential for the construction of price scenarios for planning purposes.

Jan 1, 1997

By K. W. Harris, K. A. Perry

Underground coal mines beneath Black Mountain in the Harlan County district of the Central Appalachian coalfields have an extensive history of bump events, which yields an elevated probability for significant injury or fatality to underground miners. According to Mark (2009), Harlan County has had the greatest concentration of deep-cover retreat mining in the United States. Combined with the extensive multiple seam mining history, room-and-pillar coal bumps have had a disproportionate impact on coal operations in this region. The Harlan seam, one of the principal, economically recoverable coalbeds exploited beneath Black Mountain, has a significant burst history that extends into modern times. A numerical investigation using the LaModel software of 17 bumps that occurred at the same mine in the Harlan seam was conducted and used to create a calibration methodology which serves as the quantitative basis for current and future numerical efforts in an adjacent mine exploiting the same reserve. In addition to this numerical study, a qualitative assessment of the geologic factors that are believed to contribute to the bump potential was completed. Combined with stability prediction using the numerical basis, these geologic factors will be used for recognition of high bump potential areas with the goal of reducing the potential for future bumps, helping to ensure the highest level of safety and productivity for underground personnel.

Jan 1, 2016

By Siegfried Zell

Preface Pipe heading is a customary and proven technology for the underground installation of all types of piping. In over 90 % of all cases, straight pipe sections are used between shaft constructions since, e.g. this follows roadways or it is necessary from the operational aspect due to pipe control methods, e.g. to use a remote control pipe sensor or comparable control devices within sight from shaft to shaft. Frequently, a straight pipeline is impossible, and is replaced by a more or less spatial alignment due to surface conditions, structures in the ground or foundations. This situation applied for the construction of the Nebensammler Neuland (intercepting sewer) in Hamburg-Neuland for sections IV and V. The following paper is not intended as a description of the complete project. It deals mainly with the special features of this pipe heading, with what I believe to be its somewhat unusual route. The task The building authority design issued by the Main Department for Urban Sewerage of the Free and Hanseatic City of Hamburg consisted of the construction of the collector by a pipe heading using NW 1300 pipes in 2 heading sections. One short straight and one long

Jan 1, 1989