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By Paul F. Gnirk, Ralph A. Wagner, Joe L. Ratigan

This thermomechanical analysis used the finite element method to investigate the behavior of crushed salt backfill in a waste disposal room situated in a salt dome repository. The first of two objectives was to determine the transient temperature rise and degree of thermomechanical consolidation that occur in the backfill as a function of drillhole depths. The second objective involved the evaluation of closure due to salt creep of unlined emplacement drillholes and the determination of pressure on steel sleeve liners in the drillholes should liners become necessary for canister retrieval. The retrievability period was considered to extend for 25 years after waste emplacement. The canisters were assumed to contain ten-year old high level waste with a thermal output of 4.3 kW at the time of emplacement.

Jan 1, 1981

By Hemendra N. Kalia

To plan a safe and efficient coal mining operation, the design engineer should use all the available information regarding the property to be exploited. The reliability of the mining operation must be as high as possible so that the plants relying on the coal can operate at the maximum design capacity. A good design should incorporate all of the known geological characteristics of the deposit, the structural and physical properties of the coal, as well as the rock which will form the roof and floor of the mine openings. A systematic method is proposed as a guide to insure a mine design that will be safe, efficient and will minimize surface disturbances resulting from mining operations. It is anticipated that the method proposed will result in maximum extraction at perhaps minimum cost to the operator. In general, to develop a mining area, several factors are systematically reviewed: (1) determination of the economic minability of the deposit, (2) the computation of the coal reserves, (3) the marketability of the coal, and (4) the life of the property. In general, boreholes are drilled in a predetermined pattern and geophysical or geological methods are used to log the boreholes. The information so obtained is primarily used to determine the quality and the extent of the deposit and to determine to some extent such geological features as faults, barren areas, washouts, and channels.

Jan 1, 1973

By Charles D. Litton

This Bureau of Mines paper describes a novel fire detector that can be used to discriminate between smoke produced by a fire and smoke produced by a diesel engine. The detector uses a pyrolysis technique whereby a sample of smoke- laden gas passes through a short, heated tube within which fire smoke particles pyrolyze and increase their number concentration and decrease their average size, while diesel smoke particles are unaffected. The detector is designed for use in mines that use diesel-powered equipment where the detection of fires is complicated because of the diesel emissions background levels of smoke and other products of combustion.

Jan 1, 1989

Controlled blasting experiments in small development drifts were conducted at CANMET's Experimental Mine, from August 1992 to November 1993. The objective of these experiments was to develop suitable controlled blasting techniques for small development headings drilled by jackleg with 32 mm diameter holes. The experimentation also aimed to provide insight into blast damage mechanisms. Particular attention was given to the physical-mechanical properties of the rock and the rockmass structural data in order to make the results applicable to other geological environments. The drift faces were approximately 2.4 m by 2.4 m with 36 to 43 holes drilled to a depth of 2.4 m. Cartridged water gels, emulsions and semigelatin dynamite were used in the cuts and as primers, ANFO as the main explosive and decoupled 19 mm diameter semigelatin dynamite charges were used in the perimeter holes. Smooth blasting techniques and pre-splitting were tested in the underground mine. All the blasts were monitored with a multi-channel blast vibration monitor to which was attached sets of high frequency geophones and accelerometers. This first set of experiments has illustrated the efficiency of con-trolled blasting techniques to reduce blast damage and demonstrated the need for further research to improve the safe and efficient use of explosives.

Jan 1, 1995

By Ivano Andreis, Georgios Kalamaras, Mario Liti, Sebastiano Pelizza, Filippo Avesani

"THE SS640 AGRIGENTO-CALTANISSETTA PROJECT The Caltanissetta tunnel is part of the works for the construction of the second 28km-long maxi section of the SS 640 motorway of Porto Empedocle, from km 44 to the junction of Imera in Sicilian hinterland. Amongst other major infrastructure works, the €740 million ANAS (Italian national roads and highway administration agency) project consists of four twin tube tunnels three of which are being excavated by conventional means. The longest tunnel, underpasses the Caltanissetta city and has a length of 3.9km under a maximum overburden of 120m. The JV consisting of CMC of Ravenna and TECNIS SpA won the design & built tender in 2010. Construction started in early spring 2012 following the approval of detailed design and later on the approval of design for construction. THE CALTANISSETTA TUNNEL The Design Phase Tender design and detailed design foresaw the construction of 13.4m excavation diameter tunnels that were to be enlarged in a second phase to create, every 600m, 50m-long tunnel sections for emergency parking. During the design for construction project phase the JV proposed to replace the 13.4m tunnel with a 15.08 excavation diameter that incorporated apart from the two 3.75m wide lanes a 3.25m wide continuous emergency lane. This significant tunnel section modification was associated with better road safety conditions, simpler and safer construction procedures, better statics for the tunnel section while in terms of overall cost the solutions were equivalent.Geologic context The tunnel is located in the middle of the geologically known Caltanissetta basin that is intersected by various tectonic structures. The geologic context for the tunnel scale, was defined in collaboration with the University of Catania in early project phases. For almost its entire length the tunnel is excavated in the Terravecchia formation that represents the lower part of the stratigraphic sequence that was formed in the Tortoniano period of Miocene. The quite complex geological model is also characterized by the presence of the so-called Trubi formation that consists of clay and marl clay. Almost 90% of the tunnel traverses formations that are quite similar in terms of excavation behavior. Exception to this are thrust zones and a calcareous stretch of the alignment. This last segment has a length of 200m and was identified since the very beginning as a tunneling challenge due to the combination of very poor geotechnical properties and an important water load."

Jan 1, 2016

By Keith Jones, Michael Francis

Contract 240 of the Channel Tunnel Rail Link comprises construction of twin4.7 km long running tunnels through a densely populated area of East London. The tunnels were constructed by EPBM in Sands and Sandy Clays, passing 4.4 m below the existing London Underground tunnels, and at depths of 20–30m below ground level beneath the Great Eastern railway lines into London Liverpool Street and a series of railway bridges and hundreds of buildings. This paper describes how the project team managed the challenges relating to the issue of settlement: mitigating settlement effects, prioritising the structures to be assessed, controlling resource expenditure by incentives and flexible response to urgent work relating to unforeseen events such as ground collapse and discovery of unusual structures.

Jan 1, 2005

By Richard D. Harvey

Relative quantitative analyses of certain mineralogical and textural properties of carbonate rocks were made with an image analysis computer. The instrument, referred to by its manufacturer as a Quantimet; consists of a petrographic microscope, a television camera and monitor, a detector, an electronic computer, and a read-out meter. Measurements were made on polished and etched specimens, standard thin sections, and on scanning electron micrographs of carbonate rocks. Critical to the success of the analysis is the preparation of the specimen in such a way that good optical contrast is obtained between the various petrographic components. The dolomite content, the pore volume, pore boundary projection, and pore size distribution of high-purity carbonate rocks were measured by image analysis methods. The frequency and size distribution of void inclusions in dolomites were determined by image analysis of scanning electron micrographs of cleaved surfaces. Image analysis methods permit rapid and quantitative assessment of various microscopic properties. The results are of reasonable accuracy and certainly are relative quantities that may be used to characterize carbonate rock materials.

Jan 1, 1972

By R. N. Rothan, V. Khunova, C. M. Liauw, G. C. Lees

The interphase modification activity of 1,3-phenylene dimaleimide (also known as m-phenylene bismaleimide (BMI)) has been studied in composites based on magnesium hydroxide (60% w/w) and a polypropylene block copolymer (PPBC) that featured an ethylene-rich elastomeric impact modifier phase. BMI was found to be a unique product that led to significant simultaneous improvements in composite strength and toughness, even at the high filler levels. BMI modification was found to promote encapsulation of filler particles with the elastomeric phase of the PPBC together with formation of a PP boundary layer of increased crystalline content.

Jan 1, 2003

By E. A. Barrett, L. L. Rethi

Throughout all segments of the United States mining industry, 163 independent contractor employees were fatally injured between 1990 and 1997. Factors that contributed to these injuries were identified after reviewing descriptive information contained in Mine Safety and Health Administration fatality reports for each of the incidents. Thirty-three unique contributing factors were identified and multiple factors were noted for each fatality. Those most frequently discerned were "failure to follow `standard operating procedures"', (35% of the fatalities), "poor positioning of employee" (26% of the fatalities) and "failure to maintain equipment" (23% of the fatalities). Contributing factors were then associated with the accident and job classifications of the victims. Factors having the highest frequencies in the top five accident classifications where most fatalities occurred were as follows: powered haulage - "failure to maintain equipment"; machinery - "poor positioning of employee"; slip/fall of person - "inadequate fall protection" and "failure to wear safety line"; electrical - "equipment contact with power line"; and falling/rolling/sliding rock - "poor positioning of employee. " Among the job classifications in which most fatalities occurred, leading contributing factors were as follows: truck driver - "failure to follow standard operating procedures" and "poor positioning of employee"; laborer/utility man/pumper - "poor positioning of employee"; mechanic/ repairman and welder - "failure to follow standard operating procedures." Recommendations for utilizing contributing factor information as a basis for safety training are proposed. Training programs may be developed that inform independent contractor employees of factors which, in the past, have contributed to fatal injuries in their job classifications. Then, by combining this information with contributing factors identified in "related" accident classifications, a truly focused training intervention that addresses very specific workplace hazards may he developed.

Jan 1, 2002

By M. W. Smith

Pennsylvania has 2500 miles of streams that do not meet water quality standards due to acid mine discharge (AMD), making AMD the greatest cause of water pollution in the state. The problem is mainly caused by abandoned coal mines. Pennsylvania is using a watershed-based approach to abating AMD which includes remining as a key component of a comprehensive restoration strategy. The Tangascootack Creek Watershed was targeted for AMD restoration through remining. Geologic mapping and overburden data were analyzed using Earth Vision software to identify areas of coal reserves which could be remined to improve water quality. Incentives are offered to encourage mining in these designated areas.

Jan 1, 1999

By William R. Yernberg

A conference on coalbed and coal mine methane was held March 27 and 28, 2000, in Denver, CO. The conference, organized by the Strategic Resource Institute, was attended by leaders in the coal mining and gas energy industry. The conference focused on the recovery of methane from coal beds as an energy resource and the removal and utilization of coal-mine methane (CMM) related to underground coal mining. The two-day conference discussed methane resources around the world, methods of recovery, methane markets, underground coal mining, health and safety issues and environmental issues related to methane. The consensus among the presenters is that the future looks promising for coal bed methane (CBM) and CMM.

Jan 1, 2000

By Morgan M. Sears, Mark Morris, Joseph Bright

In an effort to advance the science underlying modern coal pillar stability analysis, researchers at the National Institute for Occupational Safety and Health are currently involved in research aimed at better understanding the impact of an in-seam rock parting on the strength of coal pillars. The purpose of this study is to determine a suitable virtual mining height that could be applied using current pillar stability analysis tools. To accomplish this, the boundary element model LaModel was used to back analyze data collected on pillar performance in a room-and-pillar panel at the Maple Eagle Mine located in Southern West Virginia. In a previous work, data collected from borehole pressure cells (BPCs) and extensometers were taken from three instrumentation sites. Data collected from the back bleeders were used to measure the rear abutment stresses, and data collected from two instrumentation sites in the wraparound bleeder were used to measure the front and side abutment stresses as well as the peak strength and performance of the slabbed leave pillar. The utilization of two nearly identical instrumentation sites in the wrap-around bleeder provided much needed repeatability of the obtained measurements. In this study, the data collected from BPCs at the three instrumentation sites was calibrated to match the Bieniawski pillar stress gradient. To model the measured pillar behavior, the LaModel program was selected due to its capability of being directly comparable to the Analysis of Retreat Mining Pillar Stability (ARMPS) and Analysis of Coal Pillar Stability (ACPS) programs. The model was then calibrated to match the measured abutment extent and abutment stress. Finally, the model was validated by reducing the modeled mining height until the yielding of the slabbed leave pillars in the model matched what was measured in the field. The final calibrated mining heights show that a reduction of the shale parting thickness, not including any clay layers, of 52% is applicable. This research study provides the first known measurement of the ARMPS/ACPS “50% Rule” and its applicability to this panel of the Maple Eagle Mine. This finding provides a proof of concept and could have significant implications for future research.

Feb 1, 2024

By Shawn McWilliams, Aini Sun, Mike Lichte, Greg Colzani

The Allegheny County Sanitary Authority (ALCOSAN) adopted its Clean Water Plan (CWP) in May 2020, as part of a federal consent decree to comply with the USEPA’s Combined Sewer Overflow (CSO) Control Policy. Planned improvements include constructing a new regional storage/conveyance tunnel system, promoting green infrastructure/ source control, and expanding the treatment plant. Preliminary planning for the tunnel system was completed in October 2020. The Ohio River Tunnel (ORT) project is the first of three tunnel projects that make up the regional tunnel system. The ORT project began final design in 2021. This paper discusses the advancements made to the ORT preliminary planning concepts considering property availability, alignment optimization, tunnel boring machine evaluation, contract packaging and delivery schedules.

Jun 13, 2023

By William P. Barnett

In 1988, the US Department of Energy's (DOE) Pittsburgh Energy Technology Center identified three coal cleaning options for achieving flexible environmental control strategies aimed at reducing energy-related SO2 emissions. These are selective agglomeration, advanced froth flotation and advanced cycloning. Each relies on maximum liberation of pyrite and other mineral matter through feed coal comminution to fine and ultrafine sizes. The National Energy Strategy (NES) and the Clean Air Act Amendments (CAA) of 1990 are examples of the nation's commitment to a clean environment. The need to use the nation's energy resources in an environmentally sound manner presents critical challenges and opportunities for coal preparation during the next decade, particularly regarding the control of SO2 emissions. The principal challenge is the development of cost-effective coal preparation approaches for sulfur removal beyond currently achievable levels. Opportunities are provided in the form of incentives associated with a novel system of SO, allowances and a policy environment based on the proper functioning of familiar market forces. An allowance, as defined in Section 402(3) of the Amendments, is "an authorization ... to emit ... one ton of sulfur dioxide." To achieve the objective of the Clean Air Act Amendments, SO, emissions will be eventually capped at 8.12 Mt (8.95 million st) annually by controlling the number of allowances issued nationally. By permitting allowances to be bought and sold once issued, the law encourages "overcompliance" as a source of profit for owners of excess allowances. Many details concerning the administration of allowance trading are not yet written.

Jan 1, 1992

By S. Stebbins

In 1994 Western Mine Engineering, Inc., (WME), which is now InfoMine USA, Inc., set out to build a suite of stand-alone software programs that would provide their clients the means to estimate the costs of developing and operating mineral exploitation projects. After the first program (Sherpa for Surface Mines) was completed and launched, the developer (me) left WME to form Aventurine Engineering, Inc., in order to complete the series of applications. In the years since, four programs have either been developed or upgraded and enhanced. Applications were produced that estimate the costs of underground mining, placer mining, and project site reclamation. In addition, an application specifically designed to evaluate the economics of these projects, which was based upon a program previously developed for WME by Bill Willoughby of Willoughby & Associates, was redesigned and the code updated to a MicroSoft compatible platform. All these programs follow an engineering-based approach to cost estimating. Instead of relying on rules-of-thumb and statistical averages, they calculate all of the engineering and operational parameters needed to estimate costs. The premise is that the uncertainty associated with cost estimates should lie with the data available for the resource, not the approaches used to design and estimate the associated design parameters. In other words, it is acceptable that items such as the resource grades, deposit dimensions, ore and wall rock characteristics, and mill recovery rates carry with them some uncertainty, but parameters such as loader bucket capacities, truck speeds, pump horsepowers, hoist velocities, and grinding mill diameters can be calculated (although uncertain data might be used in those calculations). No additional uncertainties should be introduced because the cost-estimating procedure relied upon statistical manipulation or anecdotal inaccuracies. To that end, the programs rely upon calculation-based approaches to selecting and sizing machinery, assigning the required workforce, and determining the extent of the consumables needed to recover mineralized material at a rate defined by the client. And while calculation-based software is not unusual, more modern approaches work toward the development, accumulation, and manipulation of data. INITIAL CONDITIONS AND PROJECT GOALS In 2016 we had five separate programs completely disconnected from one another. Each was written in VisualBasic, a language that was falling from favor. In essence, the status in 2016 was a series of stand-alone programs (Figure 1) in which results from one needed to be manually entered as input into another.

Jan 1, 2019

By Y. A. Attia, M. Elzeky

Thiobacillus ferrooxidans bacteria were used in this work to study the effect of bacterial adaptation on the bioleaching of three iron-bearing sulfide minerals, namely, pyrite, chalcopyrite and arsenopyrite. The change in the pH during the bioleaching process was observed and the mechanism of the bacterial action were discussed. It was found that bacterial adaptation prior to bioleaching, enhanced the degree of sulfide leaching by 2-4 folds over that of non-adapted bacteria. A1 so the bacterial activity was enhanced by 2-4.8 folds. The pH of leaching solutions was decreased by the increase in both adaptation period and bioleaching time. It was also concluded that the mechanisms of bioleaching of iron-bearing sulfide minerals involved both the direct and indirect bacterial action simultaneously.

Jan 1, 1989

By R. Q. Honaker

Dense medium processes are used to clean over 50% of the coal that is fed into preparation plant facilities worldwide. The dense medium is formed using ultrafine magnetite which is recovered after the cleaning step using drain-and-rinse screens and magnetic separators. Despite the high efficiency of the recovery system, magnetite losses of around 0.5 to 1.0 kg/ton are common. Considering the recent escalation of magnetite to around $300/ton, an alternative source of magnetic material from coal combustion bottom ash has been investigated. A relatively low cost recovery system has been developed. Dense-medium tests using the bottom ash magnetics revealed a high level of efficiency as indicated by probable error values around 0.03 over the range of medium densities investigated. The results from both the recovery and coal cleaning efforts will be discussed in detail.

Jan 1, 2009

By R. W. Chappell, M. W. Hills, R. L. Olsen

A stochastic approach was developed and applied to the Butte, Montana Hillside abandoned mining site for modeling stormwater runoff and subsequent receiving stream loadings. This approach enabled capture and quantification of the uncertainty associated with stormwater quality data and allowed the prediction of copper and zinc concentrations in the receiving stream caused by runoff from the Butte Hillside during storm events. Runoff flows and stormwater concentrations were input to the model as probability distribution functions. Monte Carlo simulation allowed prediction of expected instream concentrations in the form of cumulative distributions functions. The modeling results allowed evaluation of current best management practices (BMPs), targeting of future BMPs, and identification of key data gaps to fill during future sampling activities. This modeling approach is considered extendable to other active and inactive mining sites. Output from a model of this type is easily understood and can be used to communicate effective stormwater management to site regulators. Furthermore, application of this modeling approach will facilitate the development and implementation of a site-specific stormwater management plan and will optimize efforts to achieve standards for compliance with stormwater discharge permits.

Jan 1, 2002

By Dongxu Jia, Chen Cao, Shuangwen Ma, Jun Han, Huibin Ma

Coal bump, or coal burst, is one of the catastrophic disasters in underground coalmine. Among them, approximate 80% of recorded destructive burst events were occurred in mining roadway. The bump panel is often formed by hard coal seam and hard main roof; however, the cause and course of the bump events are not understood yet. This study provides a fundamental theory for the causality and progress of a coal bump event occurred in longwall roadway. Considering hard roof condition commonly existed in bump panels, we think that the abutment pressure induced by suspended roof behind the working face is the trigger of a coal bump event occurred in the roadway. Once high abutment pressure is concentrated on the hard coal seam around the working face, the roof and the coal around the working face form a seesaw-like structure, which leads the roof in front of the working face moving upwards. The movement of roof uplifting in front of the working face is a well evidenced phenomenon in practice, namely, roof rebounding, which causes unloading of the normal stress on the roof-coal interface around the roadway. A rib coal block bump mechanical model has been developed to establish the critical equilibrium equation of the coal block. Result shows that, the force source of coal bump is the horizontal ground stress perpendicular to the rib surface; and the slippage of the coal block is caused by the unloading of the normal stress acting on the roof-coal interface. Based on the causality and consequence theory of coal bump developed in the paper, several new prediction and prevention measures have been developed, including roadway design and in-tunnel reinforcing methods. The commonly used prevention measures in present have also been discussed. This paper presents a comprehensive explanation of coal bumps occurred in longwall roadways, from abutment pressure at working face forming seesaw structure to roof rebounding leading slippage of the rib coal mass into roadway, which provides a fundamental theory for coal bump causality mechanism and prediction and prevention technology.

Apr 26, 2022

By M. K. Gangal, E. D. Dainty

The CANMET diesel-related work, carried out in cooperation with the Canadian mining industry, resulted in the identification of several useful R/D studies. One such study was the development of a dash-mounted alarm signal system to indicate overexposure of production LHD diesel vehicle operators to toxic contaminants in a mine environment. The resulting instrument has been called the [CO2 Exposure Meter]. This meter is particularly applicable to LHD machines because previous investigations have indicated that operators of LHDs and some haulage truck drivers are exposed to up to 200% of the contaminant concentrations measured in the general mine return air. This paper describes the development of the system which continuously monitors and displays the operator's exposure to diesel pollutants, and indicates an overexposure by an alarm light. The overexposure limits are preset by mine personnel based on carbon dioxide (CO2) measurements, which in turn are related to simultaneous spot respirable combustible dust (RCD) measurements (or to Air Quality Indices - AQI, if available). The CO2 settings are, in general, related to the engine/exhaust treatment selections, vehicle duty cycle and local ventilation rates and efficiency. The system continuously displays one of three lights: green for underexposure, yellow for caution, and red for overexposure. Overexposure can occur for several reasons, such as: reduced ventilation, malfunction of the diesel vehicle, and excessive airborne contaminants. The paper confirms satisfactory operation of the system in a laboratory-simulated mine environment, as well as in field trials.

Jan 1, 1993