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By Syd S. Peng

Mountaintop removal (MTR) mining started in West Virginia nearly 30 years ago. This surface mining method can extract multiple coal seams as thin as a few inches in whole and minimum rock dilution in very steep mountainous terrain. MTR is highly efficient, even if coal seams are in close proximity and small in a real extent. Consequently, MTR has been widely used in the Central Appalachian coalfield (mainly Kentucky, Tennessee, Virginia and West Virginia) with great success. In that respect, there has been no demand for research and little scientific research has been performed to investigate its impact on the surrounding area. During the past two years, however, the debate over MTR mining has grown quickly and has become very intense. This article describes chronologically issues raised by various parties, legal actions, impacts on mining permit applications and research projects developed to address the issues.

Jan 1, 2000

The purpose of this study was to investigate the immobilization as a host for metallic pollutants (Cr, Cu, Pb, and Zn) by ettringite phase. Ettringite phase is produced through hydration reaction of calcium aluminate with gypsum. From the XRD patterns, it is known that the distance between spaces in 010 planes in ettringite crystal increase with an increase of ionic radius of heavy metal except Pb; no big difference is shown. For this reason, the d-value of 010 planes in ettringite crystal increased with the substitution of Cr, Cu and Zn having a big Al ironic radius. But in case of Pb, because the substitution occurred at calcium site, it does not influence to increase d-value of 010 planes.

Jan 1, 2006

By George H. Johnson

This report describes the procedures and summarizes the results of an investigation of surface subsidence above caving blocks at the San Manuel mine, San Manuel, Ariz., in order to obtain quantitative information on subsidence and ground movement caused by mining large volumes of ore. This investigation is one part of an overall study of rock mechanics being undertaken by the Bureau of Mines. Attention was given to the improvement of a rapid and precise method of surveying a large number of subsidence pins and cracks in the surface terrain. Photogrammetric methods were used as an adjunct to the triangulation subsidence surveying as well as in ordinary topographic work Maps of various kinds were prepared to show the results obtained. The computation of the survey notes was programed for an electronic digital computer at a saving of time and expense over the use of a desk calculator and trigonometric tables.

Jan 1, 1963

By Gary L. Stecklein

This final report delineates the findings of the test programs, simulations, and analyses performed to determine the requirements for the effective application of berms and guardrails as truck restraint systems for elevated mine roadways. Included arts criterion for effective vehicle restraint for guardrail applications and recommendations for berm applications based on scale model tests and computer simulations. Full scale haulage vehicle-berm interaction field tests were performed to correlate the results of these model tests and computer simulations. Recommendations for the construction of berms were made on the basis of tests of berm bearing strength, response of the vehicle to different berms, and predictions based on the obtained correlation

Jan 1, 1981

By Za-Chieh Moh

This paper presents a summary of the current pile foundation practice in Taiwan. Constructions of driven piles, drilled shafts, and barrette foundations are reviewed. This paper also briefly summarizes the pile works of four major construction projects in Taiwan, namely, Hsin-Ta Power Plant, Taichung Power Plant, Taipei Transit Systems, and Taiwan High Speed Rail.

Jan 1, 1996

By José Cuadros

"El presente trabajo describe la aplicación del ""método gráfico de estabilidad"" como herramienta de diseño en el dimensionamiento de tajeos a través de técnicas geomecánicas que pueden ser aplicadas en otros yacimientos con similares condiciones que la mina Chupa a fin de mejorar la productividad y y mantener adecuadas condiciones de estabilidad de las excavaciones. En consecuencia, el dimensionamiento de los tajeos de Chupa fue uno de los varios trabajos que la Empresa Minera Iscaycruz S.A. realizó para el inicio de la explotación de este yacimiento a través del método de minado “tajeos por subniveles” con la utilización de taladros largos, sostenimiento con cables y relleno cementado. "

Sep 13, 2001

By Thomas M. Barczak, David P. Conover

Longwall shields provide essential ground control in longwall mining, yet a high percentage of shields are operating at less than peak capacity and many at well below the rated support capacity due to defective hydraulic cylinders or malfunctions in other hydraulic components. Leg pressure data are currently collected on state-of-the-art longwall shields, but typically are not analyzed to evaluate shield performance. The National Institute for Occupational Safety and Health (NIOSH) Shield Hydraulics Inspection and Evaluation of Leg Data (SHIELD) program is a Visual Basic software system that is designed to analyze leg pressure data and identify shields that are not performing to rated specifications. The program analysis is configured to detect the following conditions: (1) loss of leg pressure, (2) imbalance in leg pressure, (3) low set pressure, (4) low yield pressure, and (5) full extension of the bottom stage. Other performance assessment measures include the percentage of the support capacity utilized (ratio of peak load to yield load), the percent of time that a shield operates at yield load, the ratio of the set load to the yield load, and the amount of support capacity that is lost due to leaking cylinders. Historical record keeping will allow the user to select a particular shield and review the performance record as developed by the program for that shield. In addition to these performance assessment measures, the software will include an animated description of shield hydraulic systems that will describe the operation and significance of each hydraulic component and the impact of component failures on the shield’s capability to provide the required roof support. A general overview of the SHIELD program is provided in the paper together with an example analysis of a 2.5-year-old Australian longwall face.

By D. N. Bigby

This paper concentrates on ground control innovation in Europe since the first Morgantown conference, mainly from a UK perspective. In particular, it describes the rock engineering and ground control tools developed to address the mine support and design problems associated with coal mining at great depth in areas influenced by previous workings. The differences in approach across the Western European industries are also examined. Perhaps the most significant change in the period has been in the science of coal mine rock mechanics itself, with support design now based firmly on measurement, analysis and understanding. The ground control innovations described here have played their part in increasing the efficiency with which coal is mined and in increasing safety to the extent that fall of ground accidents are now rare.

Jan 1, 2006

By T Smith, J Hatley

With the increased focus on the need for more uranium mines, this paper presents the design process currently underway for the development of the Millennium deposit in northern Saskatchewan, Canada. This deposit, located 630 - 750 m below surface, will be accessed by two shafts and will be mined by blasthole stoping methods at less than 500 t/d. Mining grade will approximate two per cent U3O8 and mine life is expected to be six to seven years. The project is a joint venture between Cameco, AREVA and JCU. This paper discusses in detail methods used to predict worker radiation exposures, the methods used to monitor the work environment and procedures unique to the uranium industry necessary to minimise worker radiation exposures.

Jan 1, 2008

Grade control is a real challenge, and better sampling and modelling practices are among the tools that have proven efficient in improving it. Although based on rather trivial examples, this paper addresses the following important issues: How much of a challenge is it? How and to which degree can it be improved? And what kind of economic benefits should be expected in return for the corresponding efforts?

Jan 1, 1999

Mechanism of Modified Sodium Silicate on Fluorite Ore Flotation

Sep 13, 2010

By Rolland R. Mates

This paper describes the use of post- tensioned rock anchors to reduce the risk of future damage to a residential structure as a result of coal mine subsidence. The project described in this paper was performed by the Office of Surface Mining Reclamation and Enforcement (OSMRE) of the U. S. Department of the Interior. The OSMRE was created to administer Public Law 95-87, the Surface Mining Control and Reclamation Act of 1977. The responsibilities of OSMRE include "reclamation and restoration of land and water resources, adversely affected by past coal mining including prevention, abatement, control of coal mine subsidence. ?('l) Consequently, OSMRE has been addressing mine subsidence problems since its initial subsidence stabilization project in 1979. Stabilization activities have primarily consisted of supporting the overburden material by injecting materials through drilled bore holes into the underground mine voids. Injection of various materials into mine voids, including fly ash mixtures, coal refuse, cement grout, and gravel has proven to be a successful method of reducing mine subsidence-related surface movements, and has been extensively utilized in mitigating mine subsidence problems. However, the cost of drilling for injection can be extremely high in areas where the depth to the coal seam is great.

Jan 1, 1986

By E Hollinger, J L. Mauk

Gold-silver mineralised veins at Favona, represent a new low-sulfidation epithermal vein discovery that occurs less than 1 km southeast of the world-class Waihi deposit. The Favona vein is hosted in Late Miocene andesitic lava flows and local dacitic tuffs that are intensely altered to quartz, adularia, chlorite, illite or interstratified illite-smectite (with ten to 70 per cent smectite) and pyrite. Adularia is widespread and envelops the veins, whereas chlorite and illite are mostly restricted to the footwall, and illite-smectite is confined to the hanging wall of the Favona vein. At shallow levels, kaolinite, cristobalite and rare alunite overprint the above minerals. A polymict hydrothermal breccia also occurs above and in the hanging wall of the Favona vein and contains clasts of altered andesite and various quartz vein fragments. Fluid inclusions in quartz veins sampled over a 300 m vertical interval have a homogenisation temperature range of 175¦ to 266¦C and dilute apparent salinities of 220¦C and grading into illite-smectite and local smectite which formed at 2. In contrast, late kaolinite, cristobalite and alunite formed from descending steam-heated acid-sulfate waters. Overall, the Favona and Waihi deposits are interpreted to have formed at similar levels in a single low relief hydrothermal system, with each deposit representing a distinct zone of fluid upflow.

Jan 1, 2002

By Edward A. Barrett

The ability to recognize visual cues commonly associated with roof and rib hazards is fundamental to the prevention of groundfall accidents. The perceptual skills that miners possess to visually search and assess hazardous ground conditions differ considerably. This U.S. Bureau of Mines report summarizes recent investigations on the use of stereoscopic (3-D) slides as a training aid for improving the ability of miners to recognize the various geologic and mining-induced irregularities that cause ground-falls. The feasibility of using 3-D slides for training and their effectiveness for representing roof and rib hazard conditions are discussed. Information is presented on equipment and procedures for creating a 3-D slide program that can be updated by mine trainers. Recommendations are made on selection of 3-D equipment and on the use of 3-D slides for training miners to recognize roof and rib hazards.

Jan 1, 1988

By Pierre Gratton, Gordon Peeling

The Mining Association of Canada launched the Towards Sustainable Mining initiative in 2004. TSM’s goal is to improve the mining industry’s performance by aligning its actions with the priorities and values of Canadians. The initiative currently includes performance indicators for four areas: tailings management, energy use and greenhouse gas management, external outreach and corporate crisis management planning. Over the past year, the association has been designing a performance assessment and verification system for these performance areas, as its members prepare to move to external verification of their performance in 2006. The presentation will describe the initiative and its evolution, as well as the challenges faced in developing a verification system applicable to an entire sector.

Jan 1, 2006

By M. Roy

Safety and stability of underground coal mine workings are always in danger when opencast mines are operating in close proximity. A study was conducted to investigate the level of vibration generated from opencast blasting at similar distances on the surface as well as in the nearby operating underground coal mine openings. Eight blasts were performed and nineteen vibration data were recorded on the surface behind the opencast blasting face and also in underground openings at similar distances. It was observed that magnitude of vibration recorded on the surface were more than those recorded in underground.

Jan 1, 2007

By Y Zhang, X Yi, J Deng, J Zhao, J Song

To obtain the combustion process of a coal fire, a high-temperature programmed system is used to simulate the spontaneous combustion process of fresh and weathered coals. Both fresh coal and weathered coals from Liulingou, Inner Mongolia, China, were used to examine the gas releases from constant temperature to 650°C. Moreover, gas release rate was used to calculate the characteristic temperatures. The results showed the coal samples lasted to oxidise under high temperatures, and released plenty of heat to assist self-heating. The humic acid contained inside the weathered coal went through thermal decomposition as temperature rising and generated gases. This resulted in increasing concentrations of CO, CO2, CH4, C2H4, and C2H6. Changes of CH4, C2H4, and C2H6 gases were also similar. For weathered coal, concentrations of three gases were kept in balance under low temperatures, increased rapidly with the temperature rising. After the ignition temperature, the concentration of hydrocarbon was reduced. In addition, particle size affected coal spontaneous combustion. Coal samples with less than 0.9 mm in size produced much more CO than others. This study has examined coal spontaneous combustion caused by coal weathering during mining and its impacts on self-heating and pyrolysis in the process.CITATION:Deng, J, Song, J, Zhao, J, Zhang, Y, Yi, X and Zhang, Y, 2017. Gaseous products of weathered coal during the process of spontaneous combustion, in Proceedings Australian Mine Vent Conference 2017, pp 79–84 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By Luis-Fernando Contreras, Juliano Maran, Richard LeSueur

A risk study was carried out at the Cerrejon coal mine in order to assess the impacts of pit slope failure in terms of safety of personnel and destruction of equipment with economic consequences. Results of the assessment enabled the definition of risk treatment requirements and the identification of key aspects to consider in a risk treatment plan. The approach included the following tasks: (1) Assessment of the total probability of failure (POF) representative of the stability conditions of typical footwall and highwall slopes. For this purpose, stability analyses were carried out to define the Design POF, which accounts for the variability of strength parameters and represents the normal conditions considered for slope design. Strength parameters for highwall slope analysis were derived from borehole data obtained with a geotechnical drilling campaign. The Total POF was estimated through the use of Source Response Diagrams (SRD) in order to incorporate other sources of uncertainty not accounted for, like changes in geometry, variability of rock conditions due to geological or operational factors, changes in groundwater conditions and occurrence of seismic events. (2) Assessment of the consequences of footwall and highwall slope failure on safety of personnel. The assessment was performed through the use of event tree analysis to establish the probability of fatality caused by slope failures, from the Total POF defined in the previous task. This analysis required the evaluation of personal exposure to slope failures. Also, the assessment included benchmarking of acceptability criteria in terms of probability of fatality and the evaluation of options of risk mitigation to comply with these criteria. (3) Assessment of the consequences of footwall and highwall slope failure in terms of economic losses associated with impact on equipment. The analysis included the evaluation of equipment exposure to slope failures, and it was performed through event tree analysis to establish the probability of an economic loss associated to total or partial lost of equipment, from the total POF value defined in the first task. The magnitude of the economic losses was estimated from the costs of damaged equipment, lost production and site restoration. Options of risk mitigation were also examined in terms of economic losses. The risk assessment process applied to the Cerrejón mine showed how the system can be applied to evaluate the consequences of failure in terms of personnel safety and economics and to identify the more adequate risk mitigation options. The system can be an extremely powerful tool in the mine design process and provides the opportunity to rationalize the geotechnical information requirements, once the risk criteria have been defined by management. The main purpose of this paper is to present the process; therefore, the emphasis has been put on the methodology followed rather than on the actual results obtained.

Jan 1, 2006

By G. R. Moulder

A device was developed that measures dynamic stress (ultrasonic energy) transfer through installed rock bolts, a measure that is directly proportional to the degree of grout bonding of the bolt to the mine roof structure and thus the ability of the bolt to bear static stress. The rock bolt bond tester (RBBT) is a hand-held portable device that shows three ranges of bolt bond condition; i.e., one-third (Bad bond), two-thirds (marginal), or fully bonded. These are shown respectively by a red, yellow, or green light that displays for 4 s. RBBT performance was verified with 2 1/2-to 8-ft bolts installed in various types 0f mine roof structures (sands tone, shale, and boney coal-mud), and 15 now being tested by the Bureau of Mines in mines across the United States. The unit is about the size of a five-battery flashlight and contains the transducer electronics, and battery pack. The RBBT is designed for extreme ease of operation, requiring only manual contact with the bolt and signal read-out. The batteries are rechargeable and the package is designed for durability in a mine environment.

Jan 1, 1983

Column flotation has been successfully implemented on a production scale in the Athabasca oil sands. In this application, bitumen is recovered and mineral matter is simultaneously rejected from a middling stream originating from a primary separation vessel. Exploiting the natural hydrophobicity of bitumen, the middlings streams have traditionally been processed utilizing conventional, mechanical flotation cells. Although these cells offer adequate bitumen recovery and mineral rejection rates, operating costs are high due to the required maintenance of the wetted mechanical components. In comparison, column flotation provides superior metallurgical performance while offering a lower maintenance demand. Both metallurgical and mechanical characteristics of column flotation are discussed to demonstrate the benefits of this technology for the recovery of bitumen from oil sands.

Jan 1, 2012