Search Documents

By Rodrigo Estay Huidobro, Andrés Martinoli, Claudia Pavez-Orrego

The effects of induced seismicity caused by mining activities are one of the main problems that the mining industry faces. Although it has been documented by countries with a great mining tradition (United States, Canada, Australia and Chile) for over a century, the problem has been intensified throughout the years due to the greater depths that mineral extraction reaches, where the stress levels and environmental conditions increase the possibility of a rockburst occurrence. Seismic events inside the mine cause important losses of human lives and infrastructure damage. To deal with this problem it is necessary to implement several kinds of safety protocols. For example, seismic indicators allow to identify, through the analysis of a set of seismic parameters -magnitude, energy, time, decay rate, among others-, periods of time when a seismic event of considerable magnitude is most likely to occur. The objective of this work is to use the frictional energy generated by a microearthquake inside the mine as a seismic indicator, linking it with the occurrence of large magnitude seismic events which are outer the background activity. Thus, we seek to determine the set of seismic parameters which allow the best performance of the frictional energy/heat indicator. In the present study, we considered magnitude, frictional energy, and time as seismic parameters to study the efficiency of the proposed indicator. The optimal set of parameters was determined using two different methodologies: accumulated thermal energy and alert bands. The Piece Skill Score and the Accuracy indexes were used to evaluate each set of parameters. Both approaches show a high rate of true positive and true negative hits. Furthermore, it was concluded that both methods show complementary results in terms of the detection of critical events (Mw > 3.0).

Apr 26, 2022

By Yassine Lahmadi, Edoardo Trivellato, Christian Chereau, Bénédicte Robert

Within the framework of the adaptation of the South-East European Technicentre (Technicentre Sud-Est Européen TSEE), SNCF Voyageurs appointed Pini with the project management mission (MOE) for the design and construction monitoring of a road tunnel. This investment has a dual function: during the site transformation phase, it facilitates the work logistics (and shorten traffic flows); and in the operating phase, it is intended to ease all movements on the site over the long term. This is a limited-length gallery (50 meters) to be performed in conventional excavation below Poniatowski Avenue (Paris 12e). The excavation, crossing the entire width of the boulevard, constitutes a major challenge, given the very low coverage (less than 5.5 m), and the surrounding main infrastructures. The same project mis- sion includes the design of the tunnel accesses, via reinforced-concrete frame structures. The targeted design questions several aspects of its execution framework, and particularly, continuous operation must be guaranteed to the neighboring networks during the works. The installation of an umbrella- pipe all along the excavation profile, the progression in divided sub-sections, and the implementation of a complex monitoring system are hence key elements for limiting and controlling any deformation. An exhaustive 3D finite element modelling was performed, taking into account the detailed phasing of construction (pre-support, excavation in divided section, preliminary support and definitive lining), to dimen- sion the structures, and, overall, to analyze the impacts on the neighboring structures and facilities. During the execution phase (planned for mid-2024), monitoring activities with back-analyses as close as possible to the works are planned.

Jun 23, 2024

By CEM SENSOGUT, OZER OREN, YASAR KASAP

The mining sector, which is important in terms of raw-material and energy supply, is seen as a sector with high number of fatal accidents compared to other sectors. In this century of heightened occupational health and safety awareness, it is important to review past accident statistics and analyze current deficiencies using the information in inventory. Although there are many studies assessing occupational accidents occurring in the mining sector, there are few studies using the nonparametric linear programming method. There are many input and output parameters related to occupational health and safety. Nonparametric linear programming method has been found to be useful because it provides simultaneous evaluation of these input-output parameters, does not require functional form in the analyses and provides guidance on the improvement needed by the related parameter. However, this method analyzes data using a single period of time and does not take into account any changes in efficiency over time. In the literature, there is no study in which the change of occupational accidents occurring in mining and even other sectors over time is examined and the Malmquist total factor productivity index (MPI) is used. Within the scope of the present study, the aim was to examine the change of occupational accidents occurring in Western Lignite Corp. in Turkey, where underground and surface production methods are applied, between 2005 and 2018. It is the first time MPI is used to examine the change of occupational accidents over time. The DEAP 2.1 computer program written by Coelli [1] was used in the solution of the models [2].

By A. A. Sonntag, I. Szanto, D. A. Goodman

This paper presents the most recent developments in mixer-settler technology directed towards treating higher throughputs, increasing efficiencies and providing further improvement in SX technology with a new concept: the submerged launder. Industrial plants built in the last past few years and using these improvements are described.

Jan 1, 1993

By C. J. Gilbert

The mining method at the Cannon Mine uses heading and bench stopes, which are subsequently backfilled with cemented high-strength fill prior to pillar removal. The dimensions of the pillars, 24 feet wide by G5 to 95 feet high, re-quire careful blasting in order to not damage the rock, compromising pillar strength and complicating later removal. Additionally, the proximity of dwellings makes vibration control a must for good-neighbor relations. A blast monitoring study was conducted in order to optimize bench blasting practices to maximize fragmentation, reduce costs, minimize well damage, and minimize ground vibration.

Jan 1, 1989

By Anthony Harding

In a world of technology and electronic communication, it is easy to forget what engineers do best with a problem: sitting around a table, exchanging views and ideas with sketches and respecting everyone?s view. This was the approach adopted in the project to arrive at a solution for the cross passage opening sup-port for the Seattle University Link Extension. Schedule and space constraints usually impede concurrent cross passage excavation and tunnel boring machine (TBM) operation. And where the space is constrained, opening support solutions that maximize available cross sections are of great benefit. While there are a number of solutions that minimize space, some of these solutions can require expensive steelwork and extensive drilling and fixing. However, following a detailed round-the-table discussion of the options and constraints, it was identified that a shotcrete shell would not only limit obstruction of the space during installation, but also permit easy installation, particularly around services, and avoid costly steelwork and drilling and fixing.

By Joseph A. Zupanick

Methane drainage is a mature technology, now commonly practiced in many highly productive underground coal mines throughout the world. Universally, the practice of pre-draining methane will continue to grow as near-surface coal seams become depleted and mining operations are forced to exploit deeper reserves. These deeper coal reserves inherently have higher gas contents. In addition, increases in productivity and extraction rates have caused higher methane liberations per unit of time. As the cost of providing ventilation air increases, the economic justification for implementing a methane drainage program becomes apparent.

Jan 1, 2005

By Jeffrey Peterson, John Beesley, Martino Scialpi, John Cassidy

The DC Clean Rivers Project is DC Water's ongoing program to capture and treat combined sewer overflows (CSOs) during rainfall before they reach the District waterways. The Anacostia River system was designed to reduce CSOs into the Anacostia River and includes the Blue Plains Tunnel, Anacostia River Tunnel, First Street Tunnel, and Northeast Boundary Tunnel. A portion of the Anacostia River system was commissioned in March 2018 and the final component, the Northeast Boundary Tunnel, was placed in operation on September 15, 2023. This paper provides a summary of the experience gained during construction of this +$2.9 billion project, an overview of the system performance since its activation in 2018, and a look-ahead to the next phase of the DC Clean Rivers program: the Potomac River Tunnel.

Jun 23, 2024

By W. E. Horst

Raw materials and mineral products are crushed, ground, or pulverized for a variety of reasons. Some of the most important reasons for size reduction are: to liberate marketable mineral species from a matrix of commercial minerals and gangue, to promote rapid chemical reaction through exposure of large surface area, and to produce a material with desirable size characteristics for handling, utilization, and storage. Comminution processes are currently used on vast tonnages of raw material annually. In the mineral industries where mineral products and other solids are processed, the various size-reduction unit operations represent a major portion of the manufacturing costs. The comminution process is an expensive unit operation from the stand- point of both capital and operating costs. Power consumption is large, and the energy conversion to useful work is very small regardless of the size-reduction system. In energy terms, about 1% of the all electricity generated throughout the world is expended in crushing and grinding operations by the cement industry alone. Comminution is a general term for size reduction that may be applied without regard to the actual breakage mechanism involved. General type of size-reduction equipment include crushers, tumbling mills of various type, impact mills, fixed-path mills such as a roller mill, and fluid-energy mills. Some comminution machines accomplish

Jan 1, 1985

By G. Almgren

With the exception of sublevel caving, the most common method of underground mining in Sweden is the "cut-and-fill" method. It is normally used for mining non-ferrous metals , and' is used extensively in the complex sulfide ore mines of the Boliden Company in north and central Sweden as well as the mines of the STORA and Vieille Montagne Companies in central Sweden. All in all, the cut-and-fill method is used in 13 of Sweden's 45 mines. As the mines are relatively small, the volume of ore mined by this method represents only about 5 % of the total ore production in Sweden. The commercial value, however, is much large than this percentage would imply. The production volumes and grades of some typical mines are shown in Table I. As seen, when rated internationally, the grades are comparatively low. The prices are set according to ?international metal prices? as dictated by the London stock exchange, and in lieu of governmental support, rational management methods are critical in order to achieve satisfactory profit.

Jan 1, 1975

By Eugene E. Hively

The Tower Kill is a vertical "stirred" ball/pebble mill recently introduced in the Western Hemisphere. This device offers a significant power savings on wet fine grinding applications when compared to conventional tumbling mills. This paper describes the laboratory application of this mill wet grinding hydrated alumina to products of 50 percent passing 2 to 6 microns.

Jan 1, 1983

By D. Belin

Treatment of dilute acid mine drainage and similarly polluted water is becoming increasingly complicated. The pressure of economics is now exacerbated by legislation which classifies as hazardous waste the precipitates from conventional lime treatment plants. Since acid mine drainage invariably contains sulfate ions, one solution is to use anaerobic Desulfovibrio type bacteria to reduce the sulfate into sulphide ions which could then be used to precipitate out the heavy metals. Results are presented for both batch flask cultures and continuous column tests. Compost was used as the bacterial substrate in the column test which simulated heaps. Conditions changed from aerobic to the required anaerobic deep in the columns. Polluted feeds (up to 700 mg/l zinc) gave effluent containing well below I mg/l zinc over extended periods. Direct transfer of sulphide ions through a stream from an isolated container of bacteria is a good alternative.

Jan 1, 1991

By Emily Wortman-Wunder

While the mood at the 2013 annual joint meeting between the Pittsburgh Coal Mining Institute of America (127th Annual Meeting) and SME Pittsburgh Section (68th Annual Off-the-Record Meeting) in Canonsburg, PA was subdued following a rocky year in the coal industry, attendance was down only slightly, to 300, and overall, the meeting?s focus was optimistic about the future of coal. The conference began by addressing one of the central challenges of coal mining head-on with a keynote address on the status of safety in the mining industry. Noting that two more U.S. miners had died in 2013 than by the same date in 2012, the National Mining Association?s (NMA) Senior Vice President of Regulatory Affairs Bruce Watzman made a plea for a new approach to safety. He described the NMA CORESafety initiative, a program that promotes proactive safety measures versus a compliance-driven model. CORESafety, described in more detail on pp. 29 of this issue, focuses on developing successful ways to change company cultures of safety and behavior. Other industries that have adopted this approach have seen dramatic drops in fatalities, including the Australian mining industry, which has seen its annual fatality rate drop to nearly zero even while the number of people employed in the industry has soared. The rest of the morning?s sessions explored what is arguably the industry?s biggest challenge right now ? maintaining the social license to operate.

Jan 1, 2014

By Joseph M. Tarantino, Eric F. Perry, Keith B. C. Brady, Michael W. Smith

The Pennsylvania Department of Environmental Protection in 1998 reviewed its permitting process to determine how effective its program has been in preventing pollution and to identify here it could be improved. Of the 1,699 bituminous mine permits issued from 1987 to 1 996, 50 were identified to have current or past postmining discharges with water quality problems. The remaining 1,649 sites had no known current or past postmining discharges problems. The 50 sites were selected for further review. On closer examination, 33 of these permits no longer had water quality problems or the problem had not actually resulted from the permitted mining activity. Only 17 permits, or one percent of the total permits issued, were found to have caused long-term postmining discharges serious enough to require treatment and prevent bond release. Analysis of these 17 sites using current knowledge of mine drainage prediction, revealed that the most common cause of error was inadequate information in the permit application. Errors in interpretation of the application data and in implementing the permit were less common. A very small percentage of all permits issued resulted in postmining discharges for no clearly identifiable reason. Trends over the 10-year study period indicated a decreasing incidence of permits resulting in postmining discharges. Further, with the exception of the first few years of data, most of the postmining discharges were of mildly acidic or alkaline quality and amenable to passive treatment.

Jan 1, 2000

By Bernard A. Kilgore

Kaolin is a hydrated aluminum silicate mined primarily in middle Georgia along the "fall line", the location of the coast line in prehistoric times. It is used extensively as a filler for paper, insecticides, tires, plastics, a pigment for paints, as a coating for fine gloss paper, and for high grade ceramic products, such as catalytic converters. During its journey from the open pit mine to its final use, kaolin takes many forms, and must be handled in many different ways. The purpose of this presentation is to follow kaolin through its process and briefly describe some of the methods Georgia Kaolin Company, one of the world's largest kaolin producers, uses to handle and convey its product and some of the peculiarities involved.

Jan 1, 1983

By Michael Traylor, Michael Jatczak, Brett Robinson

The Detroit River Outfall No. 2. is an effluent water conveyance system linking the Detroit Metropolitan Wastewater Treatment Plant to the Detroit River. The 6.4m (21ft) finished diameter tunnel extends 1,890m (6,200ft) east from the bottom of a 91m(300ft) deep, 9.2m (30ft) diameter drop shaft. At the eastern terminus of the tunnel, six Riser Shafts connect the tunnel to diffuser heads on the riverbed. The tunnel runs through a highly fractured Limestone formation capable of producing high levels of groundwater in?ows and Hydrogen Sul?de gas. Control of this water and gas was a theme which ran through the entire Project’s design and construction. This paper will provide an overview of each portion of the Project’s construction, including the Entrance Shaft, Precast Concrete Segments, TBM Tunnel, Pre-Excavation Grouting Methods, and the Riser Shafts.

Jan 1, 2003

By Gregory R. Wagner

As you know, NIOSH is the part of the United States Public Health Service with responsibility for conducting and supporting research leading to prevention and control of occupational diseases and injuries. Some years ago, NIOSH went through a process of identifying and leading occupational health and safety problems in the United States. Candidate problems were evaluated in terms of the number of people affected, the importance of the effects, and how amenable the conditions are to preventive interventions. Lung diseases were ranked first on the resulting list. Diseases from mining continue to contribute substantially to this unfortunate position of prominence. The work of the Generic Center is one of many answers to this critical problem. Although the research is often expressed in terms of dust characterization or dust control, the reality is that high dust levels are much like high blood pressure. No one cares about hypertension per se. We are concerned about the consequences of exposure to untreated high blood pressure--heart disease, kidney disease, and stroke. Similarly, if dusts were truly only a nuisance, there would be little justification for the diverse research program supported by the Bureau of Mines or by NIOSH. But mineral dusts do cause a range of significant health problems: pneumoconiosis, bronchitis, and emphysema. The research supported by the Center is aimed at doing something about them. Within a public health approach to occupational health, we have a hierarchy of interventions. Primary prevention of problems is prevention at the source: solving a problem before it affects a worker. What we call secondary prevention is an attempt to identify health problems at a sufficiently early stage that some intervention will interrupt the disease process or the development of significant impairment. Tertiary prevention refers to rehabilitation of the worker who has already suffered significant loss of function. At NIOSH, and in the Generic Center research programs, the focus is on primary prevention. Basic investigations into those things about specific dusts that promote or reduce toxicity is critical for our understanding of how to prevent disease. Also, the search for engineering solutions to reduce or control dust generation is essential to solving problems of dust over-exposure. But until the engineers create the foolproof safe environment, it will also be necessary to discover better ways to identify the earliest markers of disease. To do this, we must explore and explicate the basic mechanisms of disease through laboratory investigations as well as human observation and physiologic testing. The unique opportunity provided by the Generic Center program and highlighted in this diverse program over the next few days is that these efforts are being carried out in multiple disciplines concurrently. Also, there are periodic small and large gatherings such as this one where investigators have the chance to get together, formally present papers, and informally stimulate each other's progress towards disease prevention. To ignore the potential for this cross-cutting interaction would be a significant loss. To take full advantage of it is potentially revolutionary. I recently pulled out a book I hadn't read since I was an undergraduate. It specifically concerns the nature of intellectual ferment surrounding the development of the concept of a sun-centered rather than an earth-centered universe in the sixteenth century. The book is about more than developments in astronomy: it is a discussion of the nature of scientific revolutions. Scientific revolutions result from the brilliance, insight, and good fortune of the few superimposed on the evolutionary work of the many. They both cause and reflect significant itellectural and social ferment. For example, the revolutionary work of Copernicus in recognizing the limitations of the concept of an earth-centered universe reflected contemporaneous developments in optics, mathematics, physics, economics, and philosophy.

Jan 1, 1991

By Ugo Preti, Gianfranco Ferrara, Mark C. Williams, Thomas P. Meloy

Theoretical and experimental lockedness profile curves are the same when the model assumptions are met. They appear different because of the way the data is presented. Continuous theoretical lockedness profile curves present all the data, including the wings of the curves giving them the deep U-shaped configuration. Experimental lockedness profile curves, because of the measurement methods, are discretized, obscuring the wings. If the continuous theoretical curves are discretized, they are similar to the experimental curves. When a float sink test is used to measure an interval of locked particles, the integrated averaging of the separation process obscures the wings of the continuous theoretical curve. To disclose the wings with experimental data, narrow density or measurement intervals must be used.

Jan 1, 1992

By S. B. Bhagwat

The United States has abundant coal resources that could last at least another century. and probably longer at present consumption rates. Geographically, the coal resources are distributed over the entire nation including Alaska, although there are no coal deposits in the highly populated areas on the two coasts. This allows free access to the coal, but makes transportation more expensive. Not all coals can be utilized equally because they differ vastly in quality. The sulfur content of coals, considered as the most detrimental acid rain-causing element, varies from as low as 0.3 percent in some areas of the western U.S. to 5 percent or more in parts of the Midwest. The chlorine content, which causes corrosion of plant hardware, also varies regionally. The 1990 amendments of the Clean Air Act of 1963 (CAA) require that emissions of sulfur be restricted and rolled back in two stages by the year 2000. There have been a number of reports expressing concern about the future of the industry in the states where high sulfur coal is produced. The remedies devised by the federal government and many coal-producing states in the past to "se-cure" the future of the regional coal industries have focused on the physical task of removing sulfur rather than the economic challenge of doing so at a cost that will enable high-sulfur coals to survive and compete. The past remedies, generally, were not specific enough to account for the characteristics of regional coal deposits and did not look at the coal market as an integrated national and international entity. The State of Illinois has, in recent years, taken a more comprehensive approach to the solution of the problem.

Jan 1, 1992

By Jan Wolski, Jack Barry

Ventilation ductlines with a single fan or with a series of fans are analyzed. The duct friction loss factors are discussed. Numerical solutions, presented in the paper, applies to any fan number and locations along a duct line. The findings are compared with formulas available in the technical literature. Values of the air leakage factors are presented in the SI, technical metric, and US unit systems. A method is shown of how to determine the leak- age factor for a given ductline. Optimum solutions for the sample duct lines with two and five fans in series are discussed and presented in a graphical form. Performance of fans in series is discussed in conjunction with both friction pressure loss and leak- age.

Jan 1, 1997