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By William A. Macaitis, Frank E. Dalton, Leo R. DiVita

The Metropolitan Water Reclamation District of Greater Chicago's Tunnel and Reservoir Plan (TARP) is a multi-purpose urban public works project with a total cost of $3.7 billion. Currently 51 miles of TARP tunnels are completed and operational and 34 miles are under construction. The excavated TARP tunnels have been constructed in rock utilizing 29 tunnel boring machines, ranging in size from 6.5 to 35.3 feet in diameter.

Jan 1, 1993

By M. I. Dobrynina

At the beginning of the 80-s the first diamond pipe in the East-European platform was discovered in the North of the Russian Federation on the White Sea Winter coast. During several years while studying this unique area data on kimberlites and country rocks petrophysical characteristics have been collected. Considerable experience in geophysical methods when searching and exploring diamonds was accumulated, and various methods of geophysical data interpretation were used. It has been established from the analysis of geophysical data that diamond-bearing kimberlites are located in the most ancient and the most stable block of the East-European craton.

Jan 1, 1995

By Diane Moody

I have been asked to give you the National Coal Association's (NCA) view of the future of the coal industry. However, before discussing the outlook for the future I would like to set the stage by taking a brief look at how the industry has changed over the last decade. In 1977 the coal industry was in the midst of a period of steady growth. Although most of the gains in the early and mid 1970's occurred in the west, the industry was still predominately eastern, with eastern production accounting for 76 percent of the 697 million total tons produced in 1977. The labor force was nearing a high - at over 220,000 workers, and the number of active mines was also at a decade high of over 6,000. Productivity on the other hand was at a low. The average miner produced 1.80 tons per hour, and labor relations were also at a low point. Projections for coal's future were very optimistic, mainly because of the unprecedented growth in coal use by the utility industry. In 1977 the 477 million tons of utility coal accounted for 68 percent of U.S. coal production, and the utility industry planned on 129,000 MW of new coal-fired capacity over the next decade. Consumption of metallurgical coal at coke plants was the second largest market at 78 million tons; the industrial and residential market consumed 70 million tons and exports were at 54 million tons. But in retrospect, a lot was happening in 1977 that signalled many changes in the coal industry: - Amendments to the Clean Air Act were passed, which required that utilities take an entirely different approach to meeting New Source Performance Standards at new plants, and required that standards be set for industrial boilers as well; - the Surface Mining and Reclamation Act became law; -electrical generation, despite the optimistic forecasts, was nearing the end of a period of close to five percent annual growth; -1977 ended and 1978 began with the longest coal strike in U.S. history. -crude oil imports in the U.S. reached an all time high as did both total consumption of petroleum products in the U.S. and oil consumption at utilities. The high level of oil imports set the stage for the oil price increases of 1979 and 1980 which resulted in an immediate increase in demand for coal, not only in the United States, but world wide. Labor strikes in Australia and Poland sent foreign buyers to the U.S. literally in droves, and quickly made the U.S. a force in the world steam coal market. The U.S. coal and transportation industries responded to this overwhelming potential demand for coal. In a very short time, the capability had been developed to mine and transport the 1.2 billion tons of coal that forecasters said would be needed by the mid 1980's. What was not anticipated was that the economic effects of sharply higher oil prices would dampen demand for energy, especially for electricity, as quickly as we have seen; that coal industries in other countries would respond as rapidly as the U.S. coal industry, and at a rate

Jan 1, 1988

By D. J. Turk

Faced with decreasing production from the gold heap leach operation, Robinson implemented a drilling and blasting program on the leach pads in 1993. This program offset some of the negative effects of low ore permeability and short circuiting of leach solution that resulted in lower than optimum recoveries. The drilling and blasting program created new solution flow paths and increased gold recovery. Production and pulp assays at depth intervals, prior to and following drilling and blasting, reveal the degree of short circuiting and benefits of the program.

Jan 1, 1995

By J. W. Davis

In the last few years major industrial companies have begun to realize the importance of Reliability as an enterprise strategy that, properly implemented, will improve financial performance. Typical results of an effective Enterprise Reliability Strategy include a 20% -50% reduction in maintenance cost accompanied by a 5% - 10%increase in real production capacity, with no capital investment in production equipment. One factor fueling the race to acquire and implement enterprise reliability is the pressure for companies to be increasingly cost-effective and competitive in global markets. In a recent study, Asset Productivity: The Next Wave, the Boston Consulting Group (BCG)stated that, “In order to compete for funds, companies must offer investor returns that are competitive with other opportunities. Alternative investments such as dot-com and others with non-traditional business models have raised the bar.” (APDF version of the study can be downloaded at www.bcg.com). BCG views asset productivity as the most powerful mechanism for increasing shareholder return. The author believes that the most effective way to increase Fixed Asset Productivity is to maximize asset utilization by increasing the Reliability of the Assets and the associated processes. Developing and implementing an ERS requires significant effort and knowledge. Most companies have difficulty finding a sufficient supply of these valuable commodities to implement an ERS Program internally. Many companies also struggle with figuring out how to get started and what direction to proceed.

Jan 1, 2003

By T. Hudaverdi

Airblast, the focus of the paper, is defined as blast induced atmospheric pressure waves. High overpressure levels may cause breaks of windowpanes, and plaster cracks. Additionally many mines come across psychological responses of residential areas. In this paper the monitoring of air blast is explained and evaluation procedures are defined. The allowable limits of the air blast are presented. The scaled distance approach developed for the prediction of airblast is explained. For the very rapidly growing cities, like Istanbul, the required raw materials for the construction industry are supplied from quarries in the vicinity or from inside of the city. With further growth of the population density, many quarries approach suburban areas and it will be more important to minimize the adverse effect of the blasting operations in the near future. In this paper the airblast levels that monitored in Cendere Region Quarries near Istanbul are presented. The suggestions put forward to control airblast levels.

Jan 1, 2006

By P. Cienfuegos, J. Loredo, J. J. Fernández, F. Pendás

This coal basin is a fore-deep basin with a lot of similarities with the Appalachian basin in the U.S.A., where throughout the 1990s, the research in coalbed methane grew rapidly due to a combination of factors, including the high prices for gas and electricity. In the Asturian Central Coal Basin 129 coal beds with thickness ranging from 0.8 to 1.5 m have been recognised in the productive carboniferous in an area bigger than 1500 km2. The maturation grade of these coals varies from the external zones of the basin where the volatile content ranges from 35%-40% to 20%-30%, to the internal zones of the basin where the volatile content ranges from 20% to 10%. In this context a sustainable exploration for fossil fuel is currently being undertaken in the most favourable areas of the basin in order to evaluate the real possibilities for coalbed methane (CBM) resources.

Jan 1, 2005

By M. Superfesky, P. Michael

Introduction The US Office of Surface Mining (OSM) is proposing changes to the Code of Federal Regulations in the interest of minimizing the adverse effects of excess-spoil-fill construction on the “prevailing hydrologic balance, fish, wildlife and other environmental values” (70 FR 35112). The proposed changes will require: (1) minimization the amount of excess spoil generated at a mine site; (2) minimization of the size of the fills constructed; (3) consideration of alternative configurations for disposal; and (4) development of a disposal plan that would minimize adverse impacts to the environment.1 To achieve those objectives, mining companies operating in steep-sloped Appalachia will likely build excess spoil fills (also called valley fills) that toe out at higher elevations in the hollows (i.e. to prevent or limit burial of streams). Consequently, the slopes of fill foundations will generally be steeper. Whereas the authors of this paper support these measures to protect the hydrologic balance and general environment, we wish to point out that placement of fills on steeper foundations can negatively impact the stability of the fills if proper care is not taken during their construction. It is important to note that in addition to impairing human safety, valley fill instability can negatively impact streams, the riparian habitat etc., and thus defeat the very purpose of the spoil minimization measures proposed. We do not, however, propose additional regulatory requirements pertaining to valley fill stability. Rather, we intend to emphasize the importance of engineering requirements already on the books, especially as they apply to the predominant type of valley fill constructed: the durable rock fill. We believe that the practice of restricting valley fills, to higher elevations in the watershed leaves less room for error in the design and construction of stable structures. This paper gives a quick review of the nature of excess spoil generation; methods and requirements of excess spoil fill construction, and the to-date stability record of the fills. The interest in excess spoil minimization and how it affects valley fill construction is also discussed. Most importantly, we will review long-standing issues pertaining to proper design and construction measures with respect to durable rock fills and discuss how they will become more critical as spoil minimization is practiced.

Jan 1, 2007

By Dale K. Nash

The authors have developed a com¬puter-assisted critical path planning and scheduling model to help reduce time required to move longwall mining units. The model includes time constraints and limited resource constraints, such as manpower, machinery, supplies, work space, and transportation routes. Outstanding results were achieved on the first move to which the computer-model pas applied; e.g., downtime due to the move was cut by 50%. The model and the schedules developed using it provide an excellent blueprint for future moves and have led to significant savings in time and costs for Emery Mining Corporation, Huntington, Utah.

Jan 1, 1983

By Edwin H. McKee

Eruption of rhyolitic ash-flow tuffs in the area of the McDermitt (Cordero) caldera began about 17.4 m.y. ago and continued for about 1.5 m.y. During this period of silicic eruptions, a circular area about 30 km in diameter collapsed to form a caldera that subsequently filled with sedimentary and volcanic rocks. 3 A total of more than 200 km of silicic rocks was erupted from the volcano. The final phase of igneous activity, about 15.5 m.y. ago, included resurgent doming and intrusion in the central part of the caldera. Three to 4 m.y. later +I2 m.y. ago), hydrothermal solutions using the northern part of the caldera ring fractures as conduits deposited cinnabar, pyrite, alunite, and other minerals in tuffaceous lake beds and volcanic rocks accumulated within the caldera. The ore-forming solutions may have been a residuum from the silicic magma or connate water or ground water heated by the still-hot resurgent magma in the central part of the caldera. The source of the mercury has not been identified. Later oxidation of the sulfide minerals and redistribution of the supergene minerals corderoite, several mercury nitro-oxychlorides, marcasite, iron, and titanium oxides in the sedimentary rocks account for most of the newly discovered ore body at Cordero.

Jan 1, 1976

By Chris McKee

Quartz has been of interest in occupational health for years because it can cause silicosis after prolonged exposure. New OSHA regulations (Air Contaminant; Final Rule) list perlite as a nuisance dust. They conclude that perlite is nontoxic when air-borne total particulate concentrations are 15 mg/m3 or below and when quartz content is less than 1% crystalline silica. OSHA has established an 8-hour PEL of 15 mg/m TWA for total perlite dust containing less than 1% quartz. OSHA has established a 5 mg/m3 TWA PEL for respirable perlite. These limits will protect workers from significant risk of eye, skin, or other physical irritation. This regulation is based on a Group 2A classification as a probable carcinogen in humans, at the 0.1% crystalline silica level, by the International Agency for Research on Cancer (IARC 1987a, b). IARC found sufficient evidence for carcinogenicity of crystalline silica in animals and limited evidence in humans. Perlite is not listed as a carcinogen by OSHA or the National Toxicology Program.

Jan 1, 1990

By P. M. Soupios

There is an increasing requirement for geophysical surveys carried out during geotechnical investigations to provide direct information about rock quality or other geotechnical parameters. With the paucity of information to correlate geophysical results with actual rock properties, this is still difficult to achieve and additional research effort needs to be performed to address this issue. Nowadays, several researchers have been described detailed studies which designed specifically to investigate this matter. Generally, geophysical techniques which are used to estimate seismic velocities in the subsurface focus on the low strain levels that are not large enough to induce significant nonlinear, nonelastic stress-strain behavior (Luna and Jadi, 2000), which is normally evaluated when addressing liquefaction potential of soils in the shallow subsurface. Soil parameters relevant to seismic ground response (Rechtien, 1996) are density, relative density and void ratio, permeability, shear modulus, water saturation, soil fabric and stress history. Detailed characterization of elastic properties near a major construction site (e.g. a bridge) is useful for near field dynamic analysis of soil-structure interaction (SSI) effects. The coupled effect of the bridge foundation (piles, piers or abutments) and the soil immediately surrounding these substructure elements is essential for dynamic SSI analysis of these critical bridge structures. This paper presents a geophysical investigation performed along the under construction highway of Egnatia Odos, approximately 13 km west from the town of Xanthi in N. Greece. Twelve geotechnical boreholes, drilled at the maximum depth of 75 m, approximately located 20 m from the Nestos River. The objective of the survey was to obtain the high-resolution compressional and shear wave velocities of the shallow subsurface for computation of elastic engineering properties of the unconsolidated material interposed between the investigated boreholes. Joint interpretation of borehole logs and velocity images obtained by P- and S-wave traveltime inversions outlined shallow geological anomalies.

Jan 1, 2005

By B. Hines

Grinding efficiency in a vertical stirred mill is affected by a wide range of process and mill configuration variables. Of these, the media fill, size, and intrinsic density have a significant effect on power draw and grinding performance. Media-related factors that influence grinding performance include, e.g.,a higher media filling providing additional particle breakage sites, or a lower bead density decreasing the running torque at a given media filling. It has been estimated that the grinding media can cause up to a 30% change in the specific energy required to grind. FLSmidth has generally recommended that the intrinsic density (specific gravity) of the grinding media be more than triple the slurry density. This density difference helps to ensure that sufficient stress intensity is generated in the mill to provide particle breakage. It also reduces the chance of media ?float? if there is a spike in either slurry density or slurry flow rate. The VXPmills have historically operated at slurry density values between 1.2 and 1.5 kg/L, which translates to nominal bead intrinsic density range between 3.6 and 4.5 kg/L. The current trend towards regrinding bulk flotation concentrates to even finer sizes, to improve recoveries of fine grained minerals, has provided motivation to consider closed-circuit operation of stirred media mills. The slurry density in this application is typically higher than in open-circuit operation due to the higher percent solids in cyclone underflows. An additional effect is that closed-circuit operation increases the potential for media float due to higher flow rates as slurry is recycled to the mill. The normal progression in extending the operating range of existing equipment is to carry out laboratory testing before pilot-scale and plant-scale trials. The results presented in this paper examine the media density to slurry density ratio and its effect on grinding performance.

Feb 23, 2014

By R. Bishop, J. Baggett, J. Monsalve, J. Hole, N. Ripepi, A. Abassi

This work focuses on the operational and safety issues associated with karst voids in large opening underground mines. Issues include water inrush, structural instability, and engineering uncertainty in these environments. Coupled with the fracturing prevalent in folded sedimentary rocks, karsts are complex and challenging ground control risks. Traditional methods of predicting karst locations, such as probe drilling, are impeded by the inconsistent spatial distribution and variable sizes of the features. Ground penetrating radar (GPR) is a geophysical technique that transmits radio waves into a medium and subsequently detects reflected waves via a receiver. The travel time and energy of received signals are then processed and interpreted. The difference in material properties between limestone and open karsts causes strong reflections. GPR is frequently used as a geophysical surveying technique in several industries, however there is a lack of published research on underground mining GPR applications. The purpose of this work is to prove the viability of GPR in underground stone mines for karst detection, and to discuss the importance of karst detection ahead of mining. INTRODUCTION The Mine Safety and Health Administration (MSHA) currently lists 116 active underground stone mines in the United States, the vast majority of which extract limestone for crushed stone products. These limestone mines have the potential to encounter karst voids at some point in their operation, as most karstic regions of the United States develop in limestone rock masses (Kuniansky, Weary, & Kaufmann, 2016). Karsts, the cavities formed by the dissolution of carbonate rock, have long plagued the mining and tunneling industries, as well as been a hindrance on the Earth’s surface, producing sinkholes and ruining otherwise valuable land for construction and public use. The impact of karsts on the Gavarres tunnel in Spain is well documented by Alija et al; constant instability conditions, material spills into the tunnel, and unexpected cavities seriously delayed the project deadlines and “were not foreseen in the design” (Alija, Torrijo, & Qunita-Ferreira, 2013). At the water supply project in Sohngua River, China, Bin et al detail the presence of both water and sediment filled karsts which are sources of disastrous conditions at this tunnel (Bin, et al., 2017). A hydrological tunnel in Lebanon encountered numerous massive karsts in the tunneling path which required remediation via friction anchors, rockbolts, welded wire fabric, channel steel arch segments, invert steel beams, and shotcrete (Leech, Jaoude, & Ghanem, 2008). From a design standpoint, rock mass classification schemes, such as the RMR from Bieniawski and the Q-system from Barton, are not able to represent the true nature of a karstified carbonate rock mass, and therefore complex case-by-case analyses of underground conditions are necessary (Andriani & Parise, 2017).

Jan 1, 2019

By Sylvain J. Pirson

A fluid mining process has been developed by the writer whereby phosphate deposits are leached in place through the injection of a weak and recoverable acid solution much in the same manner as in the recovery of oil by water-flooding. The phosphate mineralization is dissolved In place, selectively treated in a surface plant and a high grade diacalcium phosphate substatially free of fluorine (hence of feed grade quality) is recovered. Because of its finely divided and powdery state, the plant product is highly desirable as stock material for the manufacture of triple-superphosphate and of high grade phosphatic chemicals. Details of well completion, fluid injection, areal sweep and solution efficiency, plant design and economics are presented The rate of return on investment is particularly attractive under conditions of shallow occurrence of the phosphate mineralization such as in the Bone Valley formation of Florida. The process may also be applied economically to the Phosphoria formation of wide- spread occurrence in the Northwest United States through the application of selective formation fracturing (or Hydrofrac) previous to fluid mining operations.

Jan 1, 1959

By George K. Mitteer

The Cowles Mountain Tunnel was driven 2,073 m (6,800 ft) with a 3.43 m (11 ft 3 in) shuffle shoe TBM, for the San Diego County Water Authority, through extremely high strength granitic rock in the City of San Diego, Ca. The initial contract was $10.9 million. Tunneling began in March 1992 and all work was completed in May 1993. After the tunnel drive was completed in September 1992, a 2.44 m (96 in) Welded Steel Pipe was installed, welded and encased with cellular backfill to complete a small portion of the County's $970 million Capital Improvement Project. This paper will discuss the successful completion of a tunnel through some of the hardest most abrasive rock ever excavated with a TBM in North America.

Jan 1, 1995

By M. J. Laurila

Simulation of coal preparation circuits is becoming a widely practiced technique used for the design of coal preparation plants. On a much more limited basis, simulators are finding application in off-line process control. A typical application in the latter category involves inputting projected coal washability data for a shift into the simulator and using the software to optimize product quality and recovery within a range of predefined specifications. The plant is then operated at SG?s of separation determined from the simulation exercise for the one shift time period. This procedure is useful in that it incorporates some form of advanced planning into preparation plant operations. There is an attempt made to reflect changes in feed coal quality on a shift by shift basis rather than continually running the plant near design specifications with changes in SG?s of separation being made in response to an inadequate sampling program which only provides a spot measurement of material that has already passed through the plant. Instead of instituting changes on a shift by shift basis, NHI has proposed a method whereby monitoring three major operating parameters, * Feedrate to jig * Flowrate from hydrocyclone overflow * Density from cyclone overflow the ongoing plant operating performance can be accurately predicted on a continual basis, i.e., updated hourly. Using a distribution curve to predict the split between the clean coal and refuse from a given separator does not account for variations in efficiency that occur as a result of variations in operating parameters. NHI and Arch have studied the effect of both jig loading and solids content in the recirculating load to the jig on product quality. As a result, relatively simple measurements can be made on-line in a preparation plant which will provide input data to the simulation program that enables the prediction of jig/hydrocyclone circuit performance on a real time basis.

Jan 1, 1985

By R. A. Williams

Surface and electrochemical techniques have been used to describe the surface chemistry of ferrosilicon powders, as a function of pH and electrochemical potential, for conditions typical of operating DHS plants. The practical consequences on the likely corrosion behaviour and associated electro- kinetic particle-particle interactions (which affect stability to sedimentation) in the suspension, are discussed.

Jan 1, 1987

By A. Pomianowski

A spectrophotometric study of xanthate solutions alone and their mixtures with equimolar amounts of alkyl trimethyl ammonium bromide (CnTAB) has established the additivity of ultraviolet spectra (190 - 400 my) for potassium ethyl xanthate (KEtX) and C12TAB. No obvious effect of C12TAB addition on the decomposition rate of KEtX was observed. The kinetics of collector abstraction by copper, nickel and sphalerite powders were studied in 10-5 - 10-3M solutions of KEtX alone and in equimolar mixtures of KEtX and C12TAB. Presence of C12TAB caused a 2 - 3 fold increase in the amounts of xanthate (equivalent to many monolayers) abstracted by copper and, nickel powders but had no effect on the abstraction of xanthate by unactivated sphalerite. The adsorption of C12TAB itself from the mixed solutions was very low, at most ore monolayer only, and was not influenced by the nature of the solid powder used. The results are interpreted in terms of molecular associations and synergistic action of xanthates and quaternary amines.

Jan 1, 1963

By Bruno Bussière, Michael Aubertin, Robert P. Chapuis

Covers with capillary barrier effects (CCBE) have been used in recent years as gas barriers for the isolation of wastes, including reactive mine tailings. Capillary barrier effects help to maintain a high degree of saturation in the moisture retaining layer, which then reduces gas flux. Various factors affect the degree of saturation of the moisture retaining layer in a CCBE, such as the material water retention characteristics and layer thickness. Slope geometry can also influence the hydrogeological behaviour of a CCBE, but this factor has frequently been ignored in the past. In this paper, the authors show some results of a numerical study that illustrates the influence of slope on the behavior of capillary barriers made of different types of material. The numerical model calculations are based on an actual case of a CCBE constructed in northern Quebec. This investigation shows that the water content profile is greatly affected by the position along the slope. Thus, it is necessary to evaluate the influence of the geometry to properly establish the performance of a cover system.

Jan 1, 2000