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By A. Taghavi, I. Hassan, A. Solecki

"The Eglinton Crosstown Light Rail (LRT) Project is part of an $8.4 billion investment to expand transit in the Toronto, Canada area and is the largest transit project initiated in Province’s history. Settlement control and impact to over 1400 adjacent structures due to tunnelling was identified early as a critical project risk. The ground conditions along the 10km tunnel alignment consist of water bearing soft ground deposits (clays, sands, silts) which required careful analysis and control during design and construction. This paper will describe the process used to analyze settlements along the numerous of adjacent structures and evaluate achieved settlement results to those used during design. The paper will demonstrate that with the appropriate design specifications, selection of modernized EPB machines, and contractor performance, settlement can be maintained well below typical industry (volume loss) standards, expanding the application and suitability of soft ground tunnelling in sensitive settlement areas. INTRODUCTION The Eglinton Crosstown Light Rail Transit (LRT) Project is part of an $8.4 billion (2010$ CND) investment from the Ontario provincial government to expand transit in the Toronto, Canada area. The project is being developed by Metrolinx, an agency of the Government of Ontario to provide 19 kilometers of dedicated LRT service connecting the City of Toronto from the west to east along Eglinton Avenue. Upon completion in the year 2020, the Crosstown will be the first LRT constructed in Toronto. It will link regional and local transit, cut travel time along the route by half and provide over a thousand jobs during construction."

Jan 1, 2016

By S. Nowosad, O. Langefeld, A. Godge

Pumped storage power plants are one of the options to store the fluctuating production of electric energy from renewable sources in a sustainable manner and is able to provide Europe with the opportunity to overcome the effects of climate change. However, due to the extensive land use required when planning the water reservoirs, several projects have been declined after social conflicts raised, even in Germany. Nonetheless, after the flooding and drought periods in northern Germany, the catastrophic floods of July 2021 in south west Germany, the country’s need to decrease its dependency on import of gas and energy supply, and the energy transition goals set for 2030 and 2050, it has become clear that the implementation for water reservoirs must increase in the coming years, whether above ground or underground. Furthermore, not only Germany is interested in the use of underground cavities for water and energy storage, other European countries as Sweden are currently developing studies and solutions to bring this concept soon to reality in Europe. This article introduces the systematic approach for planning and designing large underground cavities for water reservoirs as a sustainable energy transition approach and a climate change response by showcasing the process of selection and results of the “Energy and Water Storage Harz” (EWAZ) research project. Additionally, the results of the evaluation of the effect of implementing the selected underground and surface infrastructure into the current water management system in the region is presented. Finally, the different possibilities evaluated for the underground cavities within the project and the technical challenges involved are be discussed.

Feb 1, 2023

If the communication/tracking system of an underground mine is severely damaged in a large mine accident or explosion, a surface based seismic system could be the only available tool for locating any trapped miners. This paper documents a field test of a seismic system at a room-and-pillar coal mine in Eastern Kentucky. Testing was performed at 6 different depths (450, 575, 750, 1175, 1525 and 1700 ft) above the mine. For each location underground, the miners pounded a ?set? of 5 ?repetitions? on the roof with each repetition being about one second apart. Over the 3 day field test, 63 sets of underground miners? pounding were detected by the seismic system at depths up to 1175 ft and at horizontal offsets up to 890 ft. Also during the testing, the observed signal strength generated by pounding with a crib blocks was seen to average 180% stronger than the observed signal strength generated by pounding with a sledgehammer. Ultimately, this field test was very successful and definitively demonstrated the ability of the seismic system to detect potential trapped miners? pounding up to a depth of 1175 ft.

Feb 23, 2014

By Francis G. Stehli

Though sedimentary rocks comprise only about five percent of the volume of the continental crust, they cover about 80% of its surface, serve as important reservoirs for fluids, contain reserves of non-metallic minerals, and have in general been extensively drilled. However, most drilling has been shallow in comparison to the thickness of the crust and such deep drilling as has taken place is very strongly localized in sedimentary basins. This may be seen by reference to Figures 1 and 2 which show the location of wells that drilled deeper than 15,000' [=] 4.6 km. (Figure 1) and those that drilled below 20,000' [=] 6.15 km. (Figure 2). It is apparent that, even in regions of sedimentary cover, direct exploration below six kilometers has been very restricted. In the case of the metamorphic and igneous rocks which make up 95% of the volume of the crust, direct exploration has been much less extensive in terms of both area and depth. The present state of our knowledge of the crust below a' thin surface layer stands in marked contrast to our growing present need for raw materials and the needs of future generations. It also stands in contrast to our need for enhanced, scientific knowledge of the deeper crust, its configuration, its present state, its hydrothermal systems,-its evolution, and its materials. Lessons learned in exploring the third dimension of the sea floor, the vigorous prosecution of seismic profiling, the development of testable models for hydrothermal systems and mineral deposits, the need for better understanding of heat flow, state of stress, earthquake mechanisms, and a host of other phenomena all suggest that it is time to launch a national program for scientific exploration of the crust which uses drilling to test important hypotheses developed on the basis of indirect evidence.

Jan 1, 1985

By Joseph W. Siefke

The Kramer borate deposit is located in the western Mojave Desert at Boron, California, about 100 miles northeast of Los Angeles (Figure 1). The deposit derives its name from the district in which it lies. Borax (Na2 B407.10H2O) is being mined from the Boron open pit to serve a major portion of the United States and world borate markets. This paper deals primarily with those geologic factors which affect slope stability in the overburden at the Boron open pit. Discussion includes slope failure history, slope monitoring techniques and the results of a dipmeter survey of overburden structure. Open pit mining was begun at Boron in 1957. The initial pit was successfully excavated at the recommended 1.5:1 (horizontal to vertical) slope in the overburden. During pit expansion in 1962, excavation of the overburden exposed beds dipping into the pit at +15 degrees and numerous high angle fractures associated with two intersecting fracture systems, the West Jenifer and Portal fault zones. Ensuing south and east wall failures indicated the need for more structural information in the arkose to establish better wall design criteria. Barnard and Kistler (1963) recognized that the many facies changes, faults and other variables in the Boron overburden make it extremely difficult to reduce prediction of slides to a simple arithmetical formula. Despite the difficulties and uncertain¬ties, special programs such as surface resistivity, refraction seismic and core drilling were conducted in an attempt to predict slope stability conditions and to gather geologic information. These early efforts while helpful, did not provide the necessary details of bedding orientations and fault locations which are of paramount importance in our slope stability program. A dipmeter survey in 1974 successfully measured these variables and data from that survey are instrumental in the design of slopes currently being excavated.

Jan 1, 1976

By Kevin Andrews, Zach Agioutantis

Analysis of Coal Pillar Stability (ACPS) software, released in 2018, integrates numerous empirical pillar design techniques. The ACPS program incorporates methodologies originally available as design tools from the National Institute for Occupational Safety & Health (NIOSH), including Analysis of Longwall Pillar Stability (ALPS), Analysis of Retreat Mining Pillar Stability (ARMPS), Analysis of Multiple Seam Stability (AMSS), and concepts including Coal Mine Roof Rating (CMRR), the Mark-Bieniawski pillar formula, and pressure arch loading. The design methodologies that are the basis of ACPS were developed via analysis of significant amounts of real-world data and have been standards of the United States coal industry for decades. While there are empirical factors built into ACPS, making it ideal for use in U.S. coalfields, the concepts in the program have proven to be applicable in variable mine settings, and the software was developed to allow for user-based, site-specific modifications of key design inputs. Application of ACPS to cases outside the regions for which it was developed must be approached carefully, and continuous development of site-specific data is mandatory. A case study is presented involving the application of ACPS to assess pillar stability and assist future design for an underground lignite mine in Eastern Europe. Assessment of in-mine observations, review of the geology of the lignite mine, and evaluation of specific conditions associated with a failure event resulted in “calibration” of key input factors to ACPS. Scenarios evaluated with ACPS suggest that pillar strength and overburden depth are key factors for the determination of pillar stability and design in future areas.

Jun 25, 2024

By C. E. Roessler

Uranium and its decay series are associated with phosphate deposits of marine origin. Uranium concentrations are on the order of 100 to 200 ppm in matrix from the Bone Valley formation of Central Florida and about 25% this value in matrix mined from the Hawthorne formation in North Florida. Occupational radiation exposure due to this source has been under study in Florida since the mid 1970's (Windham, Partridge, Horton 1976; Roessler and Prince 1978). This report is based on findings of an industry-wide scoping survey conducted by the University of Florida during March 1976 through May 1977 and subsequent studies in selected individual facilities. PHOSPHATE MINING OPERATIONS Mining and beneficiation operations are diagramed in Figure 1. At the excavation site, electric powered draglines remove the overburden and expose the phosphate matrix (ore) which is then slurried and pumped to the beneficiation site. At the washer stage of the beneficiation plant, the matrix is subjected to washing and screening. A coarse product, "pebble" is produced and sent to storage piles while the fine fraction is passed through a series of cyclones to remove the clays. The generated clay suspension is sent to settling ponds while the remaining sand-sized fraction is sent to the flotation plant. At the flotation plant, phosphate particles are recovered from the fine sand particles of similar size through several stages of treatment with reagents, agitation and separation of floating and sinking fractions. The high grade concentrate produced is transferred to storage while the sand tailings are discarded. [ ]

Jan 1, 1981

By Norm Steenson

Rapid excavation includes rapid support and is the central theme of this paper. Over the last few years, enormous strides forward have been made in the excavation and material handling aspects of underground excavation. However, the technology necessary to support these rapidly created openings has lagged behind the other aspects. This paper would attempt to bring you up-to-date on the progress made in bringing ground support using shotcrete into the same productivity rates as the other cyclic operations. Shotcrete has become an acceptable material for temporary and permanent support for undergound openings. However, coarse aggregate shotcrete has been an expensive construction material. It has been confined in the main to difficult ground conditions where conventional methods of support have proved to be even slower and more expensive than shotcrete. There are two main factors influencing the productivity of shotcrete equipment. (1) Structural shotcrete as opposed to gunite requires 40% to 45% rock minus 3/4" in the mix design. The equipment to handle such aggregate content has been difficult to develop on a volume basis owing to the attritional nature of the material which causes intense wear problems on

Jan 1, 1974

By J. D. Miller

The sedimentary western phosphate deposits of Idaho, Montana, Utah, and Wyoming tend to be calcareous and generally carry a significant amount of dolomite along with collophanite. In some cases, such as the Smokey Canyon Mine, Afton, Wyoming, the ore will also contain mudstone, and in this case the aluminosilicate minerals (clay, feldspar, etc.) together with some dolomite are floated from the collophanite in column flotation cells with an amine in order to meet product specifications (31 % P205) (Service et al.). In other cases, such as the SF Phosphates Limited Mine, Vernal, Utah, the ore is treated by traditional fatty acid flotation of the collophanite with mechanical flotation cells (Weber, 1986). Preliminary tests have now been conducted to evaluate air-sparged hydrocyclone (ASH) technology for the flotation of western phosphate ore. For this preliminary study, samples were taken from the hydrosizer overflow stream (18-21 % P205) at the SF Phosphates Limited Plant in Vernal, Utah for scavenger flotation testing with the 2-inch ASH system in laboratories at the University of Utah. Selected design and operating variables are being studied, and the initial results show that satisfactory separations can be achieved by high-capacity ASH flotation at appropriate operating conditions. For example, with single-stage ASH flotation 80% recovery can be obtained with a scavenger concentrate grade of about 26% P2O5. These results are comparable to, or better than, those obtained at SF plant operations with conventional flotation cells and suggest that ASH flotation technology can be used to good advantage in the phosphate industry. Of course, research should be continued to consider other process streams, optimize the separation efficiency, and evaluate larger diameter ASH units.

Jan 1, 1993

By David Rolley

The extended weakness of dollar-denominated commodity prices during the past four years has often been attributed to, among other factors, the strong rise in the value of the dollar, and many U. S. producers have hoped for a recovery in metals and minerals prices once the dollar weakened in foreign exchange markets. The recent turnaround in dollar strength may put this view to the test quite soon. Hence a review of the role of exchange rate changes in the determination of the prices of world-traded metals and minerals may be timely. This paper has three parts. Part I reviews the recent summary record of price movements in commodity and foreign exchange markets. Part 11 reviews the distinct ways in which exchange rate changes influence the supply and demand sides of a representative commodity market. Part III then more closely examines copper and aluminum prices to highlight the potential differences in the effects of exchange rate changes for commodities whose production is dominated by geology and commodities which are processing-dominated. The paper also contemplates the likely implications of these differences for commodity prices in the case of a decline in the trade-weighted dollar. The evidence suggests that the degree of recovery for dollar- measured commodity prices may be very different for differing goods. And it may be the case that some commodities whose prices appear to have been most affected by exchange rate influences may show the least recovery in response to a fall in the trade- weighted dollar.

Jan 1, 1986

By Duluth Engineers' Club, Engineers' Club of Northern Minnesota

"There are three distinct producing iron ranges in Minnesota, the Vermilion, Mesabi and Cuyuna. In trend the Vermilion and Mesabi are approximately parallel (E.N.E. and W.S.W.) and about fifteen to twenty miles apart. The Vermilion lies farthest north, near the. Canadian boundary. It is from seventy-five to eighty miles due north of Duluth. The length of its productive part is about twenty miles.The Mesabi Range is from fifty to seventy-five miles north and northwest of Duluth. Its length along the strike is about 110 miles, and the length of its present productive area about eighty miles. The Cuyuna range lies southwest of Duluth nearly ninety miles, and is the last of the Lake Superior iron ranges to be developed. The relative positions of the ranges are shown on an accompanying map. The Mesabi Range is by far the largest producer and contains the largest ore reserves of the three. The Cuyuna is next in quantity of proven ore, and in production since 1916, while the Vermilion is first in average quality of ore.On the west, both Vermilion and Mesabi ranges disappear beneath heavy glacial drift; and on the east, extend into Canada, the so-called Gunflint range near the international boundary being an eastward continuation of the Mesabi formation. This latter range is of no economic importance, however, at present. The exploration and development of the Cuyuna range has proved up a considerable tonnage of manganiferous iron ore, besides ordinary merchantable iron ore."

Jan 1, 1920

By S. Y. B. Subbarao, K. Ravindranath

Lead and Zinc concentrates are being recovered at Rajpura- Dariba (Distt. Rajsamand, Rajasthan, India) from a complex multi metal sulphide deposit since 1984 by selective flotation employing a large number of reagents. The cost of concentrates' production has been high. Due to the increased availability of concentrates world over and to be competitive, it is necessary to reduce cost of production. An effort has been made by the R.D. Department of Hindustan Zinc Limited to bring down the cost by resorting to production of Bulk Pb + Zn concentrate with enough Ag to make it attractive to the smelters. This paper gives an account of open cycle testing and locked cycle testing in the Dowa Continous Mini Flotation unit. The metallurgical data generated in the mini flotation unit indicate the possibility of obtaining smelter-acceptable bulk concentrates containing Pb+Zn 45%, Ag 400 ppm and graphite carbon about 3%. An in-plant trial in the 3000 TPD concentrator indicated that there would be savings through dispensing with and reduction in some reagents, lower power requirement, etc. Also, a substantial increase in revenue is expected due to higher recoveries by resorting to bulk concentrate production as against individual concentrates.

Jan 1, 1995

By R. L. McNearny, K. A. Barker

Four numerical models written with the "PFC2D " program were compared against four similar physical models. The numerical models were constrained numerically to closely follow the caving behavior of the physical models. Results from the numerical analyses closely simulated both the granular and blocky behaviors of the physical models, including bridging and interlocking of the simulated orebody during draw. The drawdown patterns and the rate of draw developed during numerical modeling also closely simulated the physical models. The same assumptions and governing parameters used in analyzing the first four models were applied to an additional model. The fifth model employed a completely different, uneven, draw sequence than the other four models, allowing the material to flow in a more granular manner with a demonstrated instability of the undercut sections between each drawpoint opening. Drawdown patterns and behavior of the numerical material of the first four models progressed at uneven and inconsistent rates, similar to those seen in the physical models. By inspection, the overall shape and flow lines of both the numerical and physical models were close in the area removed and in the flow characteristics. The fifth model proved to be the most unstable of all the models tested, with poor correlation to the physical models. The uneven draw sequence, coupled with an additional frictionless wall condition and an added drawpoint, caused the material to flow in a very granular manner. Information generated by this study can be used as a first approach in determining the proper draw rate, drawpoint spacing and undercut thickness for a block-caving operation. Numerical models are often difficult to predict and interpret. However, this study should increase the confidence level for use of the PFC2D program in the future.

Jan 1, 2000

By M. Wason

An Ore bed magnetic liner element is made of permanent ceramic magnets embedded in a rubber molding. (See figure 1) They are difficult and expensive to manufacture correctly. Therefore, the lining for a complete mill is expensive, as high as 400% more than conventional rubber liners. The magnets are not very resistant to impact as they are very brittle. Mills of 12 feet or more can use only I inch balls; mills under 12 feet can use balls of 1-1/2 inches. These liners are therefore used in regrind applications with small balls or in secondary pebble mills. Rubber liners for these applications last a long time, so if life was the only consideration, the pay back for these liners would be longer than the life of the mine. The Ore bed liner and its bed of ball chips or magnetic ore is relatively thin and the surface of this bed has a high coefficient of friction. The liners are made so that opposing poles are situated next to each other and that the mill shell and the bed of ore or ball chips completes the magnetic circuit. (See figure 2) The combinations of these properties results in a very efficient liner. Due to the low profile of this bed, there is no material that is lifted too high, so we have a very compact charge with very high attrition, good for fine grinding. These liners have shown a 10% ball consumption reduction and a 10% lower power draw for the same capacity. Due to the magnetic orientation, the bed is formed in a wave shape along the lines of magnetic force. Tests conducted at a copper mine in the southwest United States have confirmed these findings. The mills where the liners were tested are 10.5 feet by 16 feet Hardinge regrind mills operating as overflow ball mills.

Jan 1, 1999

By Neil J. Duncan, Edward R. Langfield

A hydraulic rock breaker was developed in Germany by Helmut Darda and uses a wedge-plug and feathers mechanism powered by a 10,000 p.s.i. power pack. During the past four years these tools have been increasingly used all over North America for secondary breaking of boulders and rock. More recently, techniques have been developed to break rock off the solid in trenches and rock emplacements where blasting is pro¬hibited or very limited. Underground operations are commencing to adopt the splitter for scaling plus including systems which can be efficiently applied to chambers and mines. Mr. Neil Duncan, who was originally scheduled to give the main part of this presentation has, during this past month accepted a position with the Alberta Energy Resources Conservation Board in Calgary. The board encourages its members to take part in seminars such as this but, unfortunately, due to the heavy pressure of work, it was impossible for him to attend this conference. Mr. Duncan has, however, forwarded me his notes and suggest¬ions, and using these, combined with a slide presentation, we feel that we can quickly and clearly define the operations and application of the hydraulic splitting technique as it applies to your profession and tunnelling work. The first question that most of you are asking is, "Why use a hydraulic splitter if you can blast?" Our answer to this is that we are not advocating the use of hydraulic splitting where blasting is feasible - but, during the past decade many applica¬tions have arisen where blasting is not allowed, or restricted

Jan 1, 1997

By H. Verakis

A fire in a coal mine conveyor belt entry represent a major safety and health risk to miners. Fighting belt entry fires can be a commanding effort. If there is a failure of one aspect in the fire fighting needs such as a dissimilar hose-valve connection, then it can result in the inability to extinguish a fire. Fire incident data compiled over nearly 30 years for underground coal mines shows that fires in belt entries account for 15-20 percent of the total number of fires. Fires in the belt entries of coal mines have resulted in injuries and fatalities. New regulations have been promulgated that require an unplanned fire not extinguished within 10 minutes of discovery to be reported to the Mine Safety and Health Administration (MSHA). A fire that is not extinguished within several minutes may take hours or days to extinguish or may require sealing a section or the mine in some cases. The current fire protection regulations in the U.S. Code of Federal Regulations (CFR), Title 30, Part 75 are designed to prevent or control the fire hazards present in a belt entry. These requirements and other factors affecting belt entry fires are discussed, including fire detection and warning, fire suppression devices, type and location of fire fighting equipment, waterlines, and cleanup and removal of combustible materials. The fire suppression systems used to extinguish/control a belt fire and the effect of ventilation on the propagation of conveyor belt fires are also discussed.

Jan 1, 2009

By Vighnesh Chandurkar, Peter Moser, Michael Hitch, Michael Tost, Susanne Feiel

"From 1998-2002 the world's leading mining and metals companies developed the Global Mining Initiative (GMI) to understand their industry's role in the transition to sustainable development and to ensure its long-term contribution to sustainable development (SD). Since then, the industry has come a long way: For example, operational safety and health have improved significantly, environmental management systems and impact assessments have become the norm, community relations have been established, many mining companies report annually on their contributions to SD and the International Council on Mining and Metals (ICMM) has taken on the recommendations of the GMI as an industry association. However, since the GMI the concept of sustainable development has been evolving from a rather generic and loose definition (“weak sustainability”), to an absolute and strict definition of sustainability, based on the boundaries of our planet (“strong sustainability”). Similarly, other concepts such as corporate social responsibility (CSR) have evolved and even deviated from their initial intentions. This paper presents results from a literature review looking at how far this transition has moved from a scientific debate towards becoming mainstream. Furthermore, it explores, by using qualitative comparison analysis, if the current efforts of the large mining companies are still sufficient or if the industry is again at risk of falling behind societal expectations and hence should once again come together - for a GMI 2.0 - in order to update its approach. We conclude that the mining industry, whilst in a “weak sustainability” position and behind the peer group on climate change and natural capital considerations, is aligned with current societal expectations, expressed through the Sustainable Development Goals, and therefore there is no need for a GMI 2.0 at present."

Jan 1, 2017

By Robert W. Bartlett

Heap biooxidation of sulfidic refractory gold ore requires large amounts of oxygen, as shown in Figure 1. Bacteria, Thiobaci/lus ferrooxidans, are donnant at oxygen concentrations below about 3% in air (1 ppm in aqueous solution) because ofmonod kinet­ics. Hence, the maximum possible utilization is only about 75%, and it may be much less than that due to poor air sweep effi­ciency. At the maximum oxygen utilization, an ore containing two percent pyrite requires nearly 100 cubic meters of air per tonne (4,000 cubic feet per ton). The stoichiometric air require­ment to oxidize arsenopyrite is similar to that of pyrite. While the leaching solution percolating through the heap introduces some dissolved oxygen, the amount is insignificant because of the low solubility of oxygen in water, 7 to 8 ppm at atmospheric saturation. There are only three ways to provide oxygen to the heap: either air flow by natural convection, diffusion of oxygen from the surface (through stagnant air in the air-filled void space in the heap), or forced air ventilation of the heap. Each of these processes will be reviewed.

Jan 1, 1996

By G. E. McCormack

The Development of Water Gel Explosives Water gels are the most recent development in the evolution of commercial explosives. They are replacing dynamite, having proven themselves to be excellent alternatives to this standard explosive. Water gels have steadily displaced dynamite over the past two decades. In 1959, they accounted for only 1 percent of the market they share with dynamite. By 1965, the share taken by water gels had grown to 21 percent. In 1970, it was more than 40 percent, and today it is nearly 70 percent. Black powder, the first widely used explosive, revolutionized mining and quarrying in its day. However, when nitroglycerin dynamite became available about a century ago, it rapidly displaced black powder because it provided greater energy for a given weight, much higher velocity for better rock shattering performance, and water resistance for easy use in wet conditions. During the past 50 years, ammonium nitrate has played a dramatically increasing role in explosives. First, it was used as an ingredient in dynamite, and then as the main component in nitrocarbonitrate blasting agents. About a quarter of a century ago, it began to find use in a simple and inexpensive mixture with fuel oil that has revolutionized the explosives industry and today fills about 80 percent of the requirements for explosives in the U.S., and certainly the bulk of blasting requirements worldwide. Water gels and dynamites share the remaining 20 percent. Water gel explosives based on ammonium nitrate have also been developed during the past quarter century. These explosives contain

Jan 1, 1979

By Julian Brown, Steve Hicks, Zach Agioutantis, Zachary Wedding

Analysis of Coal Pillar Stability (ACPS) software, released in 2018, integrates numerous empirical pillar design techniques. The ACPS program incorporates methodologies originally available as design tools from the National Institute for Occupational Safety & Health (NIOSH), including Analysis of Longwall Pillar Stability (ALPS), Analysis of Retreat Mining Pillar Stability (ARMPS), Analysis of Multiple Seam Stability (AMSS), and concepts including Coal Mine Roof Rating (CMRR), the Mark-Bieniawski pillar formula, and pressure arch loading. The design methodologies that are the basis of ACPS were developed via analysis of significant amounts of real-world data and have been standards of the United States coal industry for decades. While there are empirical factors built into ACPS, making it ideal for use in U.S. coalfields, the concepts in the program have proven to be applicable in variable mine settings, and the software was developed to allow for user-based, site-specific modifications of key design inputs. Application of ACPS to cases outside the regions for which it was developed must be approached carefully, and continuous development of site-specific data is mandatory. A case study is presented involving the application of ACPS to assess pillar stability and assist future design for an underground lignite mine in Eastern Europe. Assessment of in-mine observations, review of the geology of the lignite mine, and evaluation of specific conditions associated with a failure event resulted in “calibration” of key input factors to ACPS. Scenarios evaluated with ACPS suggest that pillar strength and overburden depth are key factors for the determination of pillar stability and design in future areas.

Jun 25, 2024