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By Ali Ebrahimi, Jeremy M. Gasser, Cuneyt Gokmen, Paul J. Sabatini, Roneet Das, William Tanner, Amir Ahmadipur

There are safety concerns related to operation of heavy equipment over coal combustion residual (CCR) impoundments during construction of the impoundment closure programs. As part of a pilot study prior to a full-scale closure construction, an access pathway and working platform were designed and constructed to facilitate equipment access for construction of deep soil mixing (DSM) zones on the ash delta of a CCR impoundment. The access pathway and working platform was constructed using shallow mass mixing with cement at the CCR surface to address safety concerns related to the geotechnical behavior of CCR. This paper describes the data from the instrumentation system which was implemented to monitor the geotechnical performance of the CCR during the pilot study. The instrumentation system included monitoring of the ground movement, vibration, and porewater pressure within the ash delta of the CCR impoundment during a pre-construction load testing, equipment mobilization over the access pathway, and DSM column installation over the working platform. INTRODUCTION A deep soil mixing (DSM) pilot study was conducted at a coal combustion residual (CCR) surface impoundment to evaluate mix designs and construction techniques for the regulatory closure. The DSM columns will create a wall which will separate and retain the CCR in a consolidated footprint separate from the closure by removal portion of the footprint and provide a barrier between the two areas of the surface impoundment. Historically, the surface impoundment received CCRs including fly ash, bottom ash, boiler slag, and gypsum, along with other byproducts produced from flue gas desulfurization (FGD). The predominant CCR in this impoundment were fly ash and bottom ash. The primary goals of the DSM pilot study were to assess the mix design strengths and to evaluate DSM construction techniques that could reach the design mixing depths of up to 90 ft. The DSM test columns were installed on the CCR delta approximately 500 ft from the nearest impoundment dikes. Another objective of the pilot study was to develop, construct, and monitor an access pathway for safe passage and movement of construction equipment on the CCR delta.

Jan 1, 2019

By J. A. Hudson, D. L. Millar

Paper presented at a meeting on: Artificial intelligence in the minerals sector, held in Nottingham, UK, 20 April 1993 (original title: Rock engineering system performance monitoring using neural networks.) Synthetic and analytical approaches to objective-based design of rock engineering projects are discussed. Rock masses are considered as complex dynamic systems with components that concurrently interact with each other and their environment. The existence of a rock engineering system canon (i.e. a set of systems governing rules) is proposed. Its possible components are highlighted and an application is demonstrated using a "rock mass automaton" designed to simulate dynamic heat distribution in rock. In the example given, the canon implements the basic result from probability theory applied to the thermodynamics of solids. Rock engineering system performance is reduced to the mapping of the output of a rockmass to varying input (design) options, within the state space of the systems model. The Kohonen Self-Organising Map provides an extremely useful analytical tool to reduce the hyper-dimensionality of rock engineering system behaviour. Further, the hyper-dimensional state vector is mapped "quasiconformally" such that the neural map tends to spatially organise similar input state vectors, facilitating interpretation of rock engineering system behaviour (performance monitoring). Work is reported on the development and validation of the automation as a basis for an internal representation of the rock mass bahaviour. The results are reported of simulations compensating for the uncertainty of the exact mechanisms operating within the rock mass, using additive noise with the input state vector in the training stages of the self-organising map implementation. Initial work on adopting Grossberg's Adaptive Resonance Theory neural network architecture for classification of rock engineering systems behaviour is also presented

Apr 1, 1994

By Wen Lan Chen

In the plant where the 800m diameter cyclone was tested, 500 STPH of 50m x 0 raw coal was pulped in a heavy medium tank and pumped originally to four 700mm heavy medium cyclones. For the test one of these units was replaced by an 800mm diameter cyclone with the subsequent feed pressure for both units sets at approximately 15.0 psi. Since this was a feed to zero plant, an appropriate bleed of heavy medium to the dilute medium circuit was established to en- sure that the cleaning of the 500m x 0.5mm raw coal would not be adversely affected by high levels of 0.5mm x 0 fine coal present in the heavy medium. The medium gravity measured varied between 1.41 and 1.43. During a three-hour test on June 10, 1983, the raw coal sample was collected from the feed belt while the clean coal and refuse samples were collected separately at proper locations along the product streams of the two different diameter cyclones. All of these samples were shipped to the laboratory for screen and sink- float analyses. The raw coal screen and ash analyses are shown in Table 1.

Jan 1, 1984

By Walter E. Jaworski, William R. Beloff, John Dunnicliff

As a step in the endeavor to reduce future tunneling costs in New York City, the Environmental Protection Administration, Dept. of Water Resources, instituted a program in 1972 to monitor the performance of the lining of one of its tunnels. A monitoring program was included as part of the contract specifications for the East Branch Interceptor Sewer tunnel for the Port Richmond Water Pollution Control Project in the hope that measured data would indicate possible future cost effective design or construction improvements. The monitoring program involved measuring ground deformations, circumferential liner stresses, longitudinal liner stresses, and jacking pressures. This paper presents some of the findings from these measurements, with emphasis on liner stresses. PROJECT DESCRIPTION The 3.05m (10 ft) diameter steel lined tunnel was constructed under two separate contracts. The easterly portion, Contract 3A, was approximately 3109m (10,200 ft) in length and constructed by Peter Kiewit Sons Co.1 The westerly portion, Contract 3B, was approximately 2160m (7100 ft) in length, and constructed by Richmond Constructors, a joint venture of Grow Tunneling Corp., MacLean Grove & Company, Inc., Grove, Shepherd. Wilson & Kruge, Inc., Morrison-Knudsen Company, Inc., and Andrew Catapano Co., Inc. Each contract included three test stations, hence a total of six along the tunnel route. Excavated material along the tunnel route consisted primarily of dense fine to coarse sand with varying percentages of gravel and silt with occasional boulders. Pockets of organic silt were encountered on Contract 3B and a large portion of Contract 3A ran through slightly weathered serpentine and schist. Overlying material and the groundwater level varied considerably along the route as did the height of overburden. Figures 1 and 2 show the generalized soil profiles for Contracts 3A (PK stations) and 3B (RC stations) respectively.

Jan 1, 1979

By C. Allen

A series of zinc chloride electrowinning tests was carried out in a laboratory scale cell to evaluate the effect of temperature, current density, electrolyte composition, gas sparging and additives on the performance of the cell with respect to current efficiency, voltage, specific energy consumption and deposit morphology. The anode material was DSA for chlorine evolution and the cathode was made of aluminum. At 400 A/m2 current density, a current efficiency of 90.9%, a voltage of 3.4 V and an energy consumption of 2.78 kWh/kg were observed. Air sparging was found beneficial but was not pursued for health and safety reasons. Various additives in the same chemical family as tetrabutyl ammonium chloride (TBAC1) were tested. Both TBAC1 and tetrabutyl ammonium bromide were found to be equally effective. Attempts to carry out the electrolysis at 1200 A/m2 were not as successful.

Jan 1, 2000

By J Y. C Lo

The construction of two drainage tunnels and the associated subvertical drain system at the Po Shan area in Hong Kong was completed in December 2009. This project is the first of its kind to utilise drainage tunnels and a network of subvertical drains to regulate the groundwater table to enhance the long-term stability of the hillside of Po Shan area.The groundwater levels, monitored by preinstalled piezometers, once exhibited dramatic drops during drilling of the subvertical drains; however, have recovered from natural replenishment after effectively plugging of the drains. The level of groundwater drawdown is in line with the design function of the subvertical drains. In order to understand the groundwater flow pattern in the Po Shan area during and after construction and to set out operation schemes for the subvertical drain system so as to control the groundwater table in the Po Shan area, a post-construction review has been carried out to examine the behaviour of the drainage system and its impact on the surrounding subsurface groundwater flow.This paper presents a review of the groundwater monitoring data during and after the construction of the drainage tunnel system covering a period of over 3.5 years. A simplified conceptual hydrological model is developed, which has been verified by the monitoring data, to capture the key elements with regard to groundwater variations in different stages of the construction. The performance of the tunnel and subvertical drain system as revealed from these field measurements is discussed.

Mar 8, 2011

By Luzheng Chen

The study aimed to evaluate the separation performance of a full-scale continuous centrifugal concentrator in the reconcentration of fine hematite from high-gradient magnetic separation (HGMS) concentrate in a tailings recovery plant, and to investigate the usefulness of the technology in industrial applications. The effect of changing the operating variables on concentrate grade and recovery was studied. The results indicate that among the variables considered in the study (water spray pressure, centrifugal acceleration, feed volume flow rate, feed percent solids and the reciprocation and spacing of water sprays), the change in centrifugal acceleration affects the recovery the most and continuous concentration can be achieved only when the water spray has a sufficient pressure. In addition, the reciprocation and spacing of the water sprays have a significant influence on the concentrate grade. Although performance of the full-scale concentrator is slightly inferior to pilot-scale trials, due to limitations in the scale-up design and the fluctuations of feed material characteristics, this concentrator provides a potential way to achieve continuous concentration and obtain a high-grade concentrate from tailings.

Jan 1, 2010

By J. Schoenbacher

Park City Municipal Corporation (PCMC), long before being recognized as an Olympic venue was known as one of the great American silver mining towns. During a century of active mining, the Park City mining district produced millions of ounces of silver in addition to a substantial amount of mine tailing waste. Since 1985 the City has been remediating these impacts with state and federal oversight. One particular challenging CERCLIS site, that was previously a historic mine tailings pond is known as Prospector Square Development (CERCLIS Listing Silver Creek Tailings UTD98051404). This site has been very challenging due to the metals that impact the shallow ground water that eventually drain into the Silver Creek Watershed. To address the water quality impairment the City and Missouri University of Science and Technology teamed up to investigate the feasibility of constructing a horizontal-flow wetland to treat this pollutant source. This effort began with the building of a pilot cell in June of 2004 and lead to the construction of a full scale horizontal-flow wetland in the fall of 2008. The design of the pilot and full scale biocell was based upon lab-scale research conducted by the Missouri University of Science and Technology. In October of 2008, the Prospector Drain effluent was introduced to the system and to date analytical results reveal that the biocell is treating the Prospector Drain outfall below the Silver Creek Total Maximum Daily Load (TMDL) endpoint goals for zinc .39 mg/L and cadmium .00075 mg/L. The water chemistry of the influent, that originates from the historic silver mine tailings pond, is impaired with zinc and cadmium and has low iron with a pH of roughly 6.5. The construction of this unit encountered many challenges related to constituent relations, regulatory scrutiny, constructability and start-up. Nonetheless, since implementation this unit is considered a success for improving water quality within the Silver Creek Watershed.

Jan 1, 2011

By Gabriella Vaschetti, Pascual Perazzo

A paper presented at Perumin 35 in 2022 described the concepts and a state-of-the-art system with extruded curbs and PVC anchor wings, adopted among others at the first four stages of Las Bambas tailings dam in Peru, discussing how upstream geomembrane water barriers can mitigate the numerous issues, including environmental aspects, of tailings dams’ design and operation. This paper, beside presenting a summary of what has been carried out so far at Las Bambas, amplifies the subject, presenting the results by means of the data of the leakage monitoring system, showing that the flow monitoring data at the downstream toe are seasonally consistent, and in alignment with design predictions.

Sep 29, 2023

By A. J. Partos

One Liberty Place, at 315 m is the tallest building in Philadelphia, PA USA. It is supported on drilled piers socketed in heterogeneous rock. 3832 kN/m2 end bearing and 383 to 766 kN/m2 shaft resistances were selected. Design load distribution was 40% on the base and 60% by shaft resistance. The maximum compression on the corner core columns is supported by clusters of 3 drilled piers. In order to confirm load distributions along shaft and at the base, Drilled Pier G-10 supporting T13-A type outrigger column was instrumented. This column supports 53,849 kN compressive load which includes 13,440 kN windload. This paper reveals details about the process to select the final design for One Liberty Place together with pertinent Information about site geology, foundation construction, quality control, and methods of steel erection. It also presents detailed Information on the type of Instruments, their calibrations, field fabrication, and installation in the shaft of Pier G-10. Readings of concrete temperatures, computed loads, and load distributions are presented for a period from October 1985 through May 1988. The building was completed in 1987.

Jan 1, 1989

By A. J. Partos

The figures and tables referred to herein are presented in the Proceedings; Volume I, Pages 309 through 316. The 61-story One Liberty Place, at 315 m., is the tallest building 1n Philadelphia and was in 1987 the ninth tallest building in the world. One Liberty Place is supported on drilled piers socketed in heterogeneous metamorphic rock. Design load distribution was 40% on the base and 60% by shaft resistance. Drilled Pier G-10 supporting a T13-A type outrigger column was instrumented. There 1s no uplift load on the exterior outrigger columns. This column supports a 53,850 kN compressive load which includes a 13,440 kN windload. Table 4 presents experimental parameters from straight line interpolation of Mohr failure envelopes for the Wissahickon schist. Lowest values of cohesion (12,200 kN/m2) and angle of internal friction (19°) are at a 50° - 59° angle of foliation. Figure 3 presents a typical pier supported by shaft resistance 1n decomposed (D) and coreable (C) rock and by end bearing (B).

Jan 1, 1991

By Jeffrey M. Listak

The Respiratory Hazards Control Branch of NIOSH routinely conducts laboratory and mine-site evaluations of dust control technologies. Gravimetric and instantaneous dust sampling instruments are used in these evaluations to measure and document dust levels to determine worker exposure. The Thermo personal DataRam (pDR) is an instantaneous sampler that uses light-scattering technology to provide relative measures of airborne respirable dust. The pDR can be used in active and passive modes to measure respirable dust levels. Tests were conducted to evaluate the sampling performance of active and passive pDR operation relative to each other and. against a gravimetric sampler (the accepted standard for respirable dust measurement). The purpose of the test was to determine if the pDR can be used effectively in the passive mode in higher velocity airflows (up to 5.1 m/s (1000 fpm)). Studies of the pDRs in both modes of operation were conducted in a controlled laboratory environment and in field situations. Dust measurements using pDR units in both modes of operation were recorded in ve¬locities ranging from 1.0 to 5.1 m/s (200 to 1000 fpm). Tests were conducted in ambi¬ent air and in air with the addition of moisture. Results show that, although the units measure different concentrations in their respective modes of operation as compared to a gravimetric sample, the relative readings can be corrected to yield accurate dust measurements.

Jan 1, 2007

The Thermo-MIE personal DataRAM dust monitor (pDR) is a light-scattering instrument approved for use in gassy underground mines by the U.S. Mine Safety and Health Administration (MSHA). However, the use of light-scattering monitors has been inhibited by concerns about inaccurate readings resulting from changes in dust size distribution and composition, as well as concerns about the impact of moisture in the mine air. Because of this concern, the National Institute for Occupational Safety and Health (NIOSH) evaluated the pDR using available data from laboratory tests and mine surveys. The data show that accuracy can vary widely from test to test and mine to mine. In most cases, the results can be improved by using a companion gravimetric measurement to adjust the pDR data.

Jan 1, 2006

By James P. Rider, Robert P. Vinson, Fred N. Kissell, Jon C. Volkwein, Gregory J. Chekan, Jay F. Colinet

The Thermo-MIE personal DataRAM dust monitor (pDR) is a light-scattering instrument approved for use in gassy underground mines by the U.S. Mine Safety and Health Administration (MSHA). However, the use of lightscattering monitors has been inhibited by concerns about inaccurate readings resulting from changes in dust size distribution and composition, as well as concerns about the impact of moisture in the mine air. Because of this concern, the National Institute for Occupational Safety and Health (NIOSH) has evaluated the pDR using available data from laboratory tests and mine surveys. The data show that accuracy can vary widely from test to test and mine to mine. In most cases, the results can be improved by using a companion gravimetric measurement to adjust the pDR data.

Jan 1, 2005

By Felipe Calizaya, Sekhar Bhattacharyya

Noise-induced hearing loss (NIHL) is prevalent in mechanized underground mines. Federal regulations are often not complied with effectively. Miners are also prone to ignoring administrative guidelines and/or personal protective equipment for hearing conservation. As a result, quality of life among experienced miners plummets while occupational risks increase at workplaces. This research focused on auxiliary fans used in underground mines. These fans work at high rotational speed and generate extremely high levels of noise in close proximity to miners. Silencers used are often of little effect due to poor maintenance. A new silencer is tried in the laboratory with the objective of easy maintenance and resulting reduction of noise exposure for miners.

By Felipe Calizaya, Sekhar Bhattacharyya

Mechanized underground mines suffer from noise overexposure. Noise levels are often above the Permissible Exposure Limit (PEL) where underground fans are used. Sound levels in active workings can reach up to 121 A-weighted decibels (dB(A)), especially when fans are not equipped with silencers. Use of silencers seldom ensures PEL. Overexposure of noise induces permanent hearing loss among mine workers. A NIOSH-funded research project and field studies at six coal and non-coal mines revalidated the findings. The University of Utah undertook laboratory studies to reduce fan noise at the source. A new silencer prototype with varying noise dampening material was designed and tested. The silencer and associated extension can be repacked with different dampening materials. The silencer and the extension were used in various configurations. Attempts were also made to simulate field conditions. The tests demonstrated a maximum sound level attenuation of about 14 dB(A) at the fan discharge. A properly designed silencer offers lesser resistance and thereby better fan performance and lower energy cost. The re-packable silencer is more likely to be maintained properly. Lowering of noise level happens in audible frequencies (4000 to 8000 Hz) which are important in A-weighting.

By M. Dondi, M. Surracco, G. Alfano, P. Saba

Recent investigations on fine grinding with jet mill miprototypes of original design, constructed at the DIMM and Centro Studi of the National Research Council at Cagliari University, have led to the realization of a third generation micronizer characterized by large capacity and high efficiency. The new model and its distinctive features are described here and the results are presented of grinding tests on typical, high grade Sardinian minerals used for quality products. The operating principles of the jet mill are described in relation to the mechanico-elastic properties of the minerals treated. In particular the efficacy of the comminution process is demonstrated in terms of both solid treated and of impact, attrition and shearing forces generated in the micronizer. Particle size distribution of the finished products are reported, that satisfy the most stringent market specifications for the different minerals, as well as energy consumptions. The alternative operating options for solving particular grinding problems and minimizing energy consumption are discussed. Lastly, the main developments of the jet mill for a possible application at industrial scale are suggested.

Jan 1, 1995

By Patzen Wu

The Hai-Shan No. 1 Coal Mine, located in northern Taiwan, is one of the typical coal mines on the island which, limited by natural condition, are mostly small in scale. With the advancing longwall method, the mine is now winning a seam, 80 cm thick, at a 32° dip, with a working depth of 824 m below surface. The annual output is about 50,000 mt of clean coal. At the working gallery, the virgin rock temperature may go up to 46°C, difficult to be brought dam to n acceptable level: because .of the tropical climate with high intake temperature and high humidity. Besides, at this depth, the intake air that goes down the long inclined shaft generates considerable heat due to autocompression. The mine is ventilated by a set of axial-flow fan with 38 m3/S of intake air at 2.2 KPA WG. With this volume of air, the temperature at the working-face is usually above 30°C WB. Appreciable lowering of the temperature is not expected even with an increased volume of ventilated air. For this reason, decision has. been made to try the installation of a pilot underground refrigeration unit near. the lowest gate road to cool the intake. air. from 32°C WB to 28°C WB which seems acceptable to on-the-spot workers exerting heavy physical labor. The experimental unit is designed for carrying away a total heat load of 90 Kw. The capacity of the unit is 200 Kw. The unit consists of a compressor, an evaporator, a condensor and a motor. The heat rejection is done in a cooling tower. Chilled water is circulated from the evaporator to the cooler by insulated pipes. The cooler consists of 90 Kw-coils with two fans and forces air by flexible ducting onto the working face. This paper examines mainly the effect of this additional reduction of working temperature, on working efficiency of the workers. Another aspect of this experiment is to evaluate the overall economy of underground refrigeration in small-sized coal mines under tropical condition. The success of such an experiment may lead to wider application of refrigeration to render many of the deeper mines economically workable.

Jan 1, 1980

By R. P. Vinson, D. P. Tuchman

The personal dust monitor (PDM) is a sampling device developed for measuring the personal exposure to coal mine dust of mine workers. The device is based on proprietary technology known as the tapered element oscillating microbalance (TEOM) originally developed as a fixed- site environmental particulate mass monitor by Rupprecht and Patashnick Co., Inc., Albany, NY. Currently, the monitoring of exposure to coal mine dust relies on periodic samples taken by traditional coal mine dust sampling units that use a cyclone, filter, pump, and laboratory measurement of the filter mass. Better measurement of mine dust levels has been the goal of industry and labor for nearly two decades. PDM technology offers accurate, end-of-shift and near real time assessment of worker dust exposure. Laboratory and underground tests compared measurements taken by a prototype PDM-2 (a two-piece TEOM) to the average of multiple personal dust samplers monitoring the same space. In the range of mass loadings P between 0.5 and 4.0 mg/m the PDM met a 25% accuracy criterion 95% of the time with 95% confidence. However, some questions still exist about potential bias between types of coal. The prototype two-piece device is in the process of being combined into a single unit that also contains the miners' cap lamp creating a more ergonomic dust sampling system.

By Edward J. Cording, William H. Hansmire

INTRODUCTION The Washington Metro, a rapid transit system that will serve the District of Columbia, Virginia, and Maryland, has been under construction for about two years. Construction of the Metro by the Washington Metropolitan Area Transit Authority involves a large amount of cut and cover, soil tunnel, and rock tunnel construction. To aid initial construction and improve future designs, performance observations were undertaken on tunnels in the initial construction phase. The University of Illinois Department of Civil Engineering was engaged to carry out a comprehensive program of field observations and measurements for this purpose. One part of the program was on the first soft ground tunnel constructed in the system. The tunnel is a 2200-ft (670 m) twin-bore section, designated Contract A-2, in downtown Washington. Two objectives of this program were to determine the relationship of construction procedure to settlements and to observe the pattern of soil movement around the tunnel as an aid in evaluating underpinning criteria for nearby structures. A test section, consisting t three instrument lines located across the tunnel path, was established prior to mining in Lafayette Park to measure in detail both vertical and lateral soil displacements as the tunnel was mined through the section. The site was selected because it is free from surface structures and access for installation and reading of the instruments was convenient. Load and distortion measurements on the lining were also made within the test section; observations of construction procedure were maintained throughout construction.

Jan 1, 1997