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By August E. Vandale

I speak to you today on the subject assigned to me, "Subsidence - a Real or Imaginary Problem", as a representative of Consolidation Coal Company (a wholly owned subsidiary of Continental Oil Company). The information I relate to you is our experience in the Pittsburgh Coal Company Division of Consol and covers the Pennsylvania properties and mines with particular emphasis on the mines in the south- western portion of the State or in the immediate vicinity of Pittsburgh, Pa. Mining of Freeport and Pittsburgh seams of coal in the Pittsburgh vicinity dates back over one hundred years. Consol, or its predecessor, Pittsburgh Coal Company, has been actively engaged in mining in the area since Pittsburgh Coal Company was organized in 1900. Pittsburgh, Pennsylvania came into prominence as the Steel City largely because of the vast reserves of high grade metallurgical coal readily available in the immediate vicinity and also because of its favorable river transportation. Early in the 1900's we operated over 100 small coal mines, with operations located in the Counties of Allegheny, Fayette, Washington, Westmoreland. We have also operated mines in Somerset and Greene Counties. Titles in Pennsylvania can be in three estates: (1) title in fee, (2) title to the mineral, (3) mining rights permitting the removal and extraction of the mineral with or without waiver of surface damage. Consol has over the years acquired good legal title to the coal lands purchased from individual farm owners, with good broad mining rights, and in 98% or more of its title has a complete waiver of surface damage or the right to subside the surface land. In the early days of our Company, individual coal farms were purchased from land owners. Many of these titles severed the coal estate from the in fee title and good mining rights with waiver of surface were conveyed in the original severance deed. Thus, minable coal reserves were put together by the purchase of the coal under many individual farms in an area. In the early years, the mines practiced hand dug mining - later going to mechanical cutting with hand loading of the coal. Systems used were entry driving with room and rib panels. We have practiced full recovery mining as far as practical during the years of hand loading, as well as in the later years when the mines were mechanized. Mining system layouts, methods and procedures have changed from time to time to keep pace with improved mining machinery and new inovations, such as roof bolting and rubber tired haulage.

Jan 1, 1967

By Thomas A. Gray

The Dolph Mine fire site is located in Lackawanna County, PA, approximately three miles northeast of the city of Scranton. The fire was burning in both coal refuse (culm) and underground anthracite mine workings. It was reportedly begun by rubbish burning on top of a culm bank. A site investigation was completed in 2006 to define the extent of the fire and to recommend fire control measures. A cut off trench was selected as the principal control method. Plans and specifications were prepared in late 2006. The project was bid and a contractor selected in early 2007. The trench construction was completed in 2007. This paper describes the investigation and selection of the fire control method and discusses the trench construction.

Jan 1, 2009

By E. J. Sullivan

This study seeks to define the mechanism of oxyanion sorption onto surfactant-modified zeolites. Zeolites which have been treated with hexadecyltrimethylammonium bromide (HDTMA) surfactant to produce a hydrophobic surface are capable of sorbing both organic compounds as well as oxyanions such as chromate, selenate, and sulfate. Simple ion exchange and charge-balancing mechanisms do not fully explain this unusual phenomenon. The sorption of HDTMA surfactant appears to be partly ion exchange and partly sorption to non-ion-exchangeable sites. Sorption of chromate is a simple exchange mechanism with bromide, which co-adsorbs with HDTMA to form a surface precipitate. Information from this study will be used to design on-site and in situ treatment systems for contaminated water, such as filter beds and permeable barriers.

Jan 1, 1995

By L. C. Bartel

Geologic features such as structure (faults, folds, fractures, etc.), water bearing zones, aquifers, pemeability variations, and porosity variations are important for mine planning and in situ energy recovery processes. Features important for planning a mine will be important for planning the recovery of energy by in situ processes. Various geophysical techniques might be used to obtain the necessary geologic information. In this paper, case histories will be discussed of the use of electromagnetic geophysical surveys at a potential underground coal gasification site and a potential tar sand oil recovery site to obtain pertinent geologic information. Results show that the controlled source audio- frequency magnetotelluric technique shows promise for mapping faults and natural fracture systems when there is a sufficient resistivity contrast.

Jan 1, 1982

By L. Landryova

The Department of Control Systems and Instrumentation, VSB - the Technical University Ostrava, has been involved in a project dealing with utilization of landfill gases, when the methane gas utilization and minimization of its release into the atmosphere was the main concern. The landfill site is generally a place, where technology for energy production can be built. The conditions for this technology implementation vary and depend on various factors. This paper is presenting findings and experience gained regarding a method of methane gas utilization for energy production. This method is concerning building bioreactors at the landfill sites, which are already operated. Every bioreactor can be thought of as a process, which is controlled in order to maximize energy production and minimize the methane gas escape into the atmosphere. The bioreactor landfill can represent a number of environmental and cost savings and, at the same time, is able to comply with all legislative issues.

Jan 1, 2005

By Mark E. Gershon

Conventional methods of drillhole site selection are reviewed briefly. Two approaches using geostatistics are then discussed, both of which have been shown to yield improved results. Finally, a branch and bound algorithm is described which will select the best locations for drilling from a user specified number of possible drill sites. Two options are discussed. First, the user can specify a maximum drilling investment or a maximum number of drillholes and the program will select the locations yielding the minimum estimation variance. This amounts to getting the most for a given investment. Alternatively, a maximum tolerable estimation variance can be specified and the program will select the number and location of the drillholes to obtain the desired information at a minimum cost. Another benefit of the approach is the quantification of the tradeoffs between investment and information obtained.

Jan 1, 1983

By B. Grosso

The National Italian Regulation concerning environment protection imposes that industrial areas are provided with systems aimed at preventing the circulation of contaminated groundwater. These systems can be static or dynamic and operate basically by intercepting the contaminated flow. Their effectiveness, realization time and costs depend on the intervention type and on the features of the specific site. The selection of the best solution is complex and the results obtained by this selection may be affected by residual risks related to the uncertainty of the hydrogeological and geotechnical characterization of the site. With regard to the industrial area of Portovesme, located in the south of Sardinia, the paper presents the analysis of alternative interventions aimed at the protection of the groundwater. The attention is focused on the evaluation of their effectiveness, impact on environment and, finally, time and costs of construction.

Jan 1, 2008

By C. Strachan

This paper presents an evaluation of the tailings dam incidents included in the 1994 US Committee on Large Dams (USCOLD) Committee on Tailings Dams report. Also, comparisons are made to water storage dam incidents from USCOLD reports, as well as to more recent tailings dam incidents. The evaluation results show that tailings dam incidents result from a number of factors, including overtopping, static and seismic instability, seepage and internal erosion, and foundation conditions. The results also show that no particular type of tailings dam or operational condition is more susceptible to incidents. In addition, the results confirm that tailings dams should be located, designed, operated and reclaimed with a thorough knowledge of site conditions, mill operation, site monitoring and tailings characteristics.

Jan 1, 2002

By J. C. Yingling, R. J. Sweigard, S. T. Mickleborough

The geostatistical technique of conditional simulation is applied to measure the uncertainty inherent in the factor-of-safety (FS) predictions for soil slopes in which there is an incomplete knowledge of the spatial distribution of soil properties. A case study that considers a natural clay slope in Canada is presented. The sequential-indicator simulation technique was used as a means of generating a series of spatial maps of the soil properties at the site. These maps approximate random draws from the conditional probability density function that characterizes existing uncertainty in the spatial distribution. FS determinations were made for each simulated map using the simplified-Janbu approach. In using this approach, computations are performed using a new computer program that can operate on irregular spatial profiles of soil properties specified on a discrete grid. A unique capability of this approach is the ability to generate the FS distribution conditional to the type, position and value of existing site-characterization measurements. This capability should reduce uncertainty in FS predictions.

Jan 1, 1996

By A. G. Sciulli, G. P. Ballock, K. K. Wu

This paper discusses common environmental problems associated with coal refuse disposal. It suggests design concepts to minimize potential hazards. Discussion focuses on site selection, embankment design and construction, site preparation, facility operation, abandonment, and reclamation. It emphasizes measures that should be adopted in the design phases and during construction of the facility. Recommendations are also made concerning special problems, including seepage, ground water contamination, and mine sealing.

Jan 1, 1987

By Joseph M. Zigich

The Anaconda Minerals Company operates a molybdenite and copper producing mine and mill facility near Tonopah, Nevada. Included with the milling facility is a ferric chloride leach plant for removal of copper mineralization from the molybdenite concentrates. Discussed are the engineering and construction schedules associated with the leach plant. The chemistry associated with the process along with a description of the process flow, equipment, and operating parameters are contained in the paper.

Jan 1, 1983

By Andrew P. Gize

The analytical approaches used to solve a specific problem are dependent upon the information required, coupled with limitations imposed by available facilities, costs, and time. The organic matter associated with ore deposits has the potential to yield information for two problems. Information can be obtained to provide guidelines for prospecting, and, secondly, to solve genetic problems. A major potential of organic matter in providing prospecting guides lies in the high thermal sensitivity of organic matter in sediments which are metamorphosed at grades lower than greenschist facies. The organic matter can then be used to map thermal anomalies potentially associated with mineralization. The analytical approach is to determine the thermal maturity of the total organic matter, or of specific fractions, using techniques which are relatively quick and inexpensive. Consideration of genetic models (for example, reduction, complexing, involvement of oil field brines) generally requires more specific information than the overall thermal maturity of the organic matter, necessitating infor¬mation on molecular composition and structure. The facilities, time, and cost of this information are greater than for mapping thermal anomalies. The analytical techniques discussed include elemental analyses, spectroscopy (infra-red, visible and ultra-violet), Fourier Transform infra-red, nuclear magnetic resonance, extraction, pyrolysis techniques, chromatography and mass spectrometry.

Jan 1, 2013

By Patrick Oriez, Chris Norris, Alain Mercusot

"Temporary mechanical ventilation is one of the fundamental requirements in guaranteeing a healthy atmosphere in underground construction works in order to protect the health of persons working on the site. It is therefore essential to conceive a system which meets the requirements of the whole of the worksite and for all phases of work which takes into account all aspects pertaining to its design, dimensioning, justification, installation, maintenance and validation. In doing so, the ventilation design and the selected apparatus to be installed shall meet with the degree of health protection and the quality of air of the worksite as defined by the legislation in force in France, through limiting the concentration of the different pollutants associated with the site activities. Consequently, when presenting a mechanical ventilation project, all of the participating parties and especially the contractor make a commitment to guarantee sufficient volumes (or airflow rates) of fresh (non-polluted and oxygenated) air and extracted (polluted) air in order to meet these limitations and maintain them in all conceivable site configurations. This article sets out the most important aspects of the implementation of a ventilation project from the initial design stage through to its application, discussing French legislation, ventilation principles, calculations and techniques with regards to underground construction sites. BASICS OF VENTILATION Mechanical ventilation studies are concerned with all of the site workstations and work phases which are sources of pollution and apply to all zones of the underground worksite with the goal of maintaining the concentration or composition of this pollution below the permitted levels and comply with the following three basic principles which are complementary to one another without being in contradiction. •,The first principle consists in eliminating or limiting as much as possible the emission of any polluting, irritant, or dangerous substances, by specifying appropriate construction techniques and equipment (use of electric motors, combustion engine equipment: filters, tanks, catalyzers, use of less polluting explosives, damping down dust with water or wetting products, damping down and diluting certain gases using water mists). •,The second principle is designed to capture residual polluting substances emitted close to the source in order to prevent them from spreading into the worksite atmosphere (extraction ventilation with ducting up to the source – upstream of the extractor fan – and use of downstream filters before expelling the polluted air to the exterior). •,The third principle involves accompanying the capture of the pollutants with additional blowing ventilation specific treatment of substances dissipated by and distant from the source of pollution (acceleration of the drift air flow in order to confine dust and better capture it, supply ventilation with ducting in order to dilute the gases emitted and discharge them to the exterior)."

Jan 1, 2016

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 C. Don Sullivan

Paraphrasing the poetic repetition of Gertrude Stein - "Research is research, is research, is research --- ad infinitum." But research takes many forms and involves many facets. Perhaps the most simple of definitions is that attributed to the late "Boss" Kettering of General Motors who in advising a young trainee said, "Research is an intelligent effort to satisfy the curiosity of the human mind." Reclamation research is complex and requires a diversity of scientific knowledge. The overall aim of land reclamation research is directed to finding practical ways to develop efficient methods to restore mined lands to productive use, compatible with use of adjacent lands, as soon after mining as possible; and, finding practical ways to reduce or prevent damage to surrounding resource areas, which may be affected by the mining process. Research in the field of mined land reclamation is not entirely new, although in some respects we are exploring new areas each day.

Jan 1, 1967

By Francois J. E. Scholtz, Raymond J. Davidson, Peter Greenhalgh, R. Paul Riley

A 1 t/d continuous elution pilot plan is being operated by General Mining at their Grootvlei Gold Mine using the technology developed at the Anglo American Research Laboratories. Flowsheet design and plant erection was carried out by Van Eck & Lurie and completed in December 1989. Following the conclusion of six test runs designed to optimise reagent additions, it was shown that elution efficiencies of 98-99% could be achieved using reagent additions as· low as 16 kg/ton of carbon NaCN and 28 kg/ton NaOH while consistently producing eluted carbon containing less than 50 g/t gold. Significant savings were indicated when compared and power were indicated when com­pared with the traditional batch AARL, Zadra and Micron alcohol elution procedures.

Jan 1, 1990

By Sepp A. Kutschera

are gaining increased interest for over­burden removal and ore production at large open cast mines. The application of bucket wheel excavators is still tied to soft un­consolidated rocks and soils, while belt conveyors can cope with all kind of matri­als restricted only by the top grain _ size. Therefore, mode of transport and the re­quirement of down stream ore processing de­fine the materials size distribution. These requirements are usually met by primary crushing or scalping. The paper discusses general applica­ tion criteria of bucket wheel excavator with systems primary for in-pit overburden crusher removal. and It _indeapits scalper units and discusses their technical and operational features. It further com­pares the capital and operating cost struc­ture relative to the syste

Jan 1, 1992

By S. S. Peng

An expert team consisting of geology, civil, and mining engineer professors was organized to investigate several problems of longwall mining in three mine sites including: site investigation, panel layout and support selection, overburden strata movement, surface subsidence and structural damages, slope, stability, well and stream dewatering, etc. The results include the development of a PC software package such as powered support selection, Surface subsidence prediction, optimum panel dimension, and pillar design.

Jan 1, 1989

By Dale R. Ralston, Roy E. Williams, Gerry V. Winter, George L. Bloomsburg

Ground water inflow into a mine and the re¬sultant impact on district hydrology can be pre¬dicted on a site specific basis once the ground water flow systems at the site are sufficiently well under¬stood so that a valid conceptual model can be de¬veloped. Ground water flow systems are controlled by the hydrogeologic properties of the materials at the, site, including hydraulic continuity along flow paths, and boundary conditions. Preliminary delin¬eation of hydrostratigraphic units for conceptual models frequently can be based on surface water data; specifically, spring locations and the gain-loss reaches of streams. Quantitative predictions of mine water inflow and its impact on regional hydrology require col¬lection and analysis of numerous types of data. Hydraulic conductivity must be defined quantita¬tively both parallel and perpendicular to bedding as well as areally for each hydrostratigraphic unit. The characteristics of the Davis shale in case his¬tory number 2 illustrate this concept very well. The storage characteristics also must be determined for each hydrostratigraphic unit and the potential or hydrostatic head should be quantified vertically and areally for each unit. The potentiometric measure¬ments in the Bonneterre Formation as discussed in case history number 2 illustrate this point. The data collection and data analysis techniques constitute the weak link in the analysis of mine inflow and district impact. The technology for char¬acterizing a mine site in the field has lagged behind the technology for mathematical simulation; we at¬tribute this development to the fact that computer modeling is relatively inexpensive compared to field data collection and analysis. On-site tests provide the best means of quan¬tifying hydraulic conductivity parallel to bedding and the storage characteristics of the unit. Pump tests with multiple observation wells provide the best information from on site tests. Hydrogeologie boundaries can be located from such multiple well tests. Multiport piezometers provide a means for determining the vertical potential in a single borehole. Borehole geophysics can facilitate the def¬inition of hydrostratigraphic units. Vertical hy¬draulic conductivity is difficult but not impossible to quantify with existing field test methods; labo¬ratory tests of cores fail to give a value represent¬ative of the field situation. The storage characteristics of a confined (artesian) hydro¬stratigraphic unit can be difficult to quantify when pumping changes the confined unit to an uncon¬fined (water table) case after depressurization and dewatering. Transmissivity and storage coefficient can be approximated to some extent for given field con¬ditions by computer modeling if enough is known about hydrogeologic boundaries. Modeling can be used in a trial-and-error approach to match transmissivity and storage coefficients to existing water level data corresponding to estimated discharge rates. A solution can also be obtained using a tech¬nique referred to as the inverse method. Unfortu¬nately, such a solution is seldom unique. Fracture flow models exist but practicality usu¬ally necessitates reversion to a basic Darcy flow model. Data requirements for fracture flow models could be difficult to fulfill where fracture aperture, spacing, orientation, and length are required. Ob¬taining such data at depth prior to mining would be impossible for any mine simulation in fractured media. We are of the opinion that most fractured media simulations can be accomplished using con¬ventional Darcy flow models by viewing the field problem on a macroscopic scale. The real challenge is to delineate hydrostratigraphic units properly in the field. The question of whether a broken-up fault zone is an aquifer or a barrier boundary is seldom simple. The fractures usually can be treated as an equivalent porous medium in either case. Only a few techniques exist for predicting un¬derground mine water inflow. These techniques fre¬quently are designed to evaluate shaft or tunnel inflow under steady-state head conditions in a sin¬gle layer rather than in multiple hydrostratigraphic units. Few computer programs exist that have the

Jan 1, 1986

By Roland Heersink, Charles H. Wells

This paper discusses how a mill uses off-site data hosting approach to effectively utilize an entire suite of advanced applications to optimize daily operations, without incurring the overhead of on-site systems, staff and support. Details of the solution are provided, together with a live view of actual plant operations. Security and authentication mechanisms are also outlined so that users may gain an appreciation of the actual security of the remotely hosted data. A number of Web-hosted software applications provide direct connectivity to the database offering rapid and deterministic response times to clients. A 24x7 help-desk is available to authorized users from any Internet connected device. The paper shows how mill management advantageously use wireless PDA's to view what is going on at anytime and from anywhere. It concludes with a summary of how the approach is being used to speed decision-making and capture spot market opportunities.

Jan 1, 2002