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By Terry McMahon

This Bureau of Mines report describes the rock burst problem and measures being taken for its alleviation in the deep underground mines of the Coeur d?Alene Mining District in northern Idaho. The geologic features that contribute to rock bursting in that area are discussed and briefly compared with similar features in other burst-prone mining districts throughout the world. Early investigations to understand and control rock bursting are reviewed, and the mechanics of bursting are discussed in terms of the seismic events that produce them. Sources of strain energy, rock failure mechanisms, and the conditions necessary for the release of seismic energy are covered in detail. Rock burst research in the Coeur d'Alene District is described. Included are discussions of the microseismic method as both a research tool and as a rock burst monitoring system, rock destress blasting and preconditioning methods for rock burst control, and stoping methods currently being developed to reduce rock burst hazards.

Jan 1, 1988

A paper presenting an overview of legislative and best practice approaches to the management of OHS&E and business risk for Australian tunnelling operations. Best practice can be achieved in Australian tunnelling through ærisk awarenessÆ by decision-makers and line personnel. This will identify problems before they occur and lead to implementing controls appropriate to avoiding loss throughout the life cycle of the underground opening. The author draws on legislative approaches from all Australian states together with practical experience from risk management and risk engineering work from six recent tunnelling projects. This describes a process that:commences with concept risk assessment,involves quantification of major hazards,conducts assessments of operating risks, andleads to implementation of an integrated management system that keeps construction activities connected with the controls identified in the design and planning phases and minimises the losses sustained as a result. Key points addressed include:where the industry is going with respect to risk û methods and considerations,how tunnelling risks are perceived by the industry and legislation,how tunnel constructors and owners can minimise exposure by using proper risk engineering ætoolsÆ, andreflections on best practice methods for transferring knowledge from designers to contractors/operators.

Jan 1, 2008

By Thomas H. Wilson

Common offset and refraction seismic data have been collected over four longwall panels at two different locations within West Virginia. Surveys prior, during and after mining were made in both areas. The velocity of seismic wave propagation in the overburden rocks is observed to decrease in response to panel emplacement. Variations in the magnitude of this reduction, apparent as an additional first arrival time delay in the after mining common offset surveys, do not appear to correlate directly to the amount of subsidence that has occurred. Velocity reduction and signal absorption zones are also produced in the cover beyond the panel face over the adjacent unmined areas. Signal absorption and velocity reduction zones have also been observed over room and pillar entry areas between mined panels. Velocity reduction zones have been- observed beyond the panel face in both shallow and deep mines, but the signal absorption zone has not been observed over the deeper mine. Changes in the compressional wave velocities of the cover rocks are associated with changes in their elastic moduli. Differences between borehole derived and surface seismic derived interval velocities, are related to differences in the properties of the bulk volume sampled by each method.

Jan 1, 1988

By Leon Lorenzen, Charlene Gokhale

"In excess of 24 x 106 tons (Eskom, 1997) of coal-derived fly ash is produced annually in South Africa for the production of electric power. A large quantity of this ash is disposed of as a solid waste in landfills, thus posing a serious environmental problem. Due to the shortage of landfill sites, new ways of utilising fly ash are needed. Recently several authors have shown that various combustion fly ashes can be converted into zeolites to obtain industrial products with applicability in environmental management. Geopolymerisation has emerged during the last few years as a possible solution to some waste stabilisation and solidification problems. henolic compounds have been shown to be toxic to soil microorganisms at the parts-per-million level. Indeed several of the organic compounds classified by the U.S. Environmental Protection Agency as priority pollutants, are phenols. Immobilisation of phenols by adsorption on zeolites and encapsulation in a geopolymer appears to be a promising solution to this problem.This paper reports a technique for the production of a low-silica sodium zeolitic material from fly ash (zeolite NaP1), and its application for the stabilisation of phenols by adsorption and subsequent encapsulation in a geopolymer matrix. A commercial zeolite, clinoptilolite was also utilised as an adsorbent. Due to their uniform pore sizes and large surface areas, zeolitic materials are suitable for ion exchange and adsorption of certain organic substances. Adsorption data show that the commercial zeolite, clinoptilolite was an effective adsorbent for organics. Adsorption data showed that between 51.2 ppm and 74.3 ppm of chlorophenol or between 15.4 ppm and 32.5 ppm of phenol could be adsorbed. Physical encapsulation of the coated zeolite loaded with organic within a geopolymeric matrix increased the compressive strength of the matrix from 28.80 kN to 40.79 kN. Leaching data for the various geopolymer matrices with encapsulated and loaded zeolites show no organics being leached from the system at a detection level of 2ppm. According to the SABS these would have been acceptable organic concentrations within a waste water stream."

Jan 1, 2003

By S. Jiansheng, H. Nakayama, D. Lu, A. Wang

ABSTRACT: New techniques and methods for 3D geo-mechanical model test are presented in this paper. The new model material NIOS with high density and low cost; the so-called DPSS (Discrete Principal Stress Surface) loading concept, the loading and monitoring system for the generation of the 3D initial stress field of the model test, also the special techniques and apparatuses for modelling the excavation of caverns located deep inside the model material, are developed and introduced. By adopting those new techniques, a very large 3D geo-mechanical model test with high comparability for a newly designed underground powerhouse has been successfully fulfilled. Key Words: 3D model test, underground group caverns, excavation process modeling. ZUSAMMENFASSUNG: Neue Techniken und Methoden für 3D geomechanischen Modellversuch wurden in diesem Artikel vorgestellt. Ein neues Modellmaterial mit hocher Dichte und niedrigem Preis, ein sogenanntes DPSS (Discrete principal stress surface) Ladenkonzept, ein Laden- und Überwachungssystem für die Erzeugung des 3D primären Spannungsfelds und überdies spezielle Techniken und Maschinen für das Ausbruch der tief in dem Versuchsmodell liegenden Kaverne wurden entwickelt. Bei Anwendungen dieser neuen entwickelten Techniken wurde ein sehr großer 3D Modellversuch mit großem Maßstab für ein geplantes unterirdisches Kraftwerk erfolgreich durchgeführt. Stichworte: 3D Modellversuch, unterirdischen Gruppekaverne, Ausbruchsmodellierung Résumé: le test de modèl de Nouvelles techniques et méthodes pour la géo-mécanique 3D est figuré dans ce papier. Le nouveau modèle de matériels NIOS avec la haute densité et le coût bas; la conception proposée de chargement DPSS (Discrete Principal Stress Surface), le système de chargement et de moniteur pour la génération de champs de stress initial du test de modèle, ainsi que les techniques et appareils spéciaux pour modeler les excavations de cavernes profondément localisées dans l’intérieur du matériel de modèle, sont développés et introduits. A travers l’adoptation de ces nouveaux techniques, le test de modèle de la géo-mécanique très large 3D avec la haute comparabilité pour actualiser une nouvelle étude de la centrale électrique sous-terraine a déjà accompli avec succès. Mots de clé: test de modèle 3D, groupes de cavernes sous-terraines, processus de modèle d’excavation

Jan 1, 2003

By E. Barsky

"The aim of separation is to obtain two products that are as distinct as possible from each other. It is currently believed that the most objective criteria for the quality of a separation are the Hancock criterion and the entropy criterion.1. Hancock criterion:- for yield of fine product"

Jan 1, 2003

By G. Krogman, C. Walla, B. Wood

The Gebo Mining District (District) is located in the Bighorn Basin of Wyoming. Commercial underground coal mining began in 1906 with the arrival of the railroad in Thermopolis, which is located approximately 11 miles to the south. Mining in the District ceased by the early 1970’s. In Fall of 1999, Lidstone and Associates, Inc. (LA) and their subcontractors were retained by the Wyoming Abandoned Mine Land Division (WyAML) to perform an inventory of over 500 abandoned mine sites across Wyoming. During the summer of 2000 field inventory, a 30-foot deep headcut (Figure 1) and sink-hole were noted in the West Fork of Sand Draw (WFSD), immediately west of the Town of Gebo. The headcut and sink-hole were located at the culvert outfall associated with a stream crossing of a relatively well traveled county road. Upon further investigation, it appeared that underground mine workings had been exposed at this location. This resulted in a condition whereby water would be conveyed directly into the mine workings during a runoff event. The exposed mine workings as well as stream capture created a very hazardous condition. The WyAML implemented mitigation measures in the summer of 2000 by constructing a temporary stream crossing upstream of the existing failed crossing. To address this hazardous situation as well as a number of other hazards identified in the District during the field inventory, the WyAML retained PHC Reclamation, Inc. (PHC). PHC was directed to perform a field investigation and develop a Reclamation Plan to address all existing abandoned mine hazards in the District. Federal, state, and private parties own lands within the District. Hazards identified during the investigation included an underground mine fire, open adits, open shafts, subsidence, drainage problems, and coal slack. A Report of Investigation (ROI) was submitted to various regulatory agencies that documented the existing conditions and conceptual reclamation plans to remediate the hazardous conditions. After review of the ROI by the US Department of Interior - Bureau of Land Management (BLM) an on-site meeting was conducted. BLM Cultural Resource personnel declined to approve a District reclamation project until a historical overview of the entire District was prepared. Due to the hazardous situation associated with the WFSD stream crossing, Hot Springs County Road and Bridge Department convinced various state and federal regulatory agencies to allow reclamation of the stream crossing to occur. A decision was made to allow reclamation on privately owned lands within the WFSD drainage. This decision limited the amount of channel that could be subjected to reclamation upstream of the crossing to privately owned lands. PHC contracted LA to perform a geologic, geomorphic, hydrologic, and hydraulic investigation of the drainage to assist in the development of a WFSD reclamation plan. LA’s investigation consisted of four parts: Delineate the extent of mine workings in the area; Identify all drainage structures that required mitigation; Survey a series of channel cross-sections and a longitudinal profile of the impacted channel; and, Develop basin hydrology to assist in the design of a stable reclaimed stream channel.

Jan 1, 2006

By J. Hines

Traditionally, fuel oil or diesel was the collector of choice in coal flotation, but in recent years these materials have come under increased scrutiny because of concerns about the toxicity of some components. In response to these concerns, Georgia-Pacific Chemicals LLC has commercialized a patent pending coal collector (Talon® 9400 reagent) that is 100% derived from the pulping of trees. This study presents a comparison of yields and recoveries for different coal collectors, including the one derived from the pulping of trees.

Jan 1, 2011

Assessment of the Consistency Between Different Laboratory Froth Stability Measurements

Sep 13, 2010

Pilot-Plant Testing of Ammoniacal-Cyanidation for Gold Recovery from Copper Gold-Bearing Ore The results of pilot-plant tested ammoniacal-cyanidation of gold recovery from copper gold-bearing ore are presented in this paper. This ore is from a deposit of Russian Federation with gold and copper grade 9.5 g/t and 0.4 per cent, respectively. Copper is largely present as malachite and azurite. The presence of chalcopyrite and bornite is also observed. In order to recover gold, gravity is recommended. Two options of ammoniacal-cyanidation using leaching of gravity tails, CIP and filtration, were tested. It was found that ammoniacal-cyanidation using filtration of leaching tailings and recycled solutions is the most optimal option. The proposed flow sheet provides for 89.7 per cent gold recovery from gravity tailings at the consumption of NaCN 0.9 kg/t and (NH4)2CO3 7.5 - 9 kg/t. Compared to conventional cyanidation, this technology decreases the consumption of sodium cyanide from 4 up to 0.9 kg/t at the same gold recovery. It can be recommended for the treatment of copper gold-bearing ores with the similar composition.

Sep 13, 2010

By F. B. Samani, B. Stabel

The 1,000 MW Hydro Power Station Masjed-e-Soleiman (formerly called Godar-e-Landar) in Iran is under construction since 1992. The rock engineering aspects of the major underground structure, i.e. the powerhouse cavern shall be reported on in detail. The geotechnical investigations are described and results given. The results of several geotechnical analyses are presented. The designed and executed rock support is given. A description of the monitoring systems and typical measurement results obtained during and after excavation are presented. The lessons learnt during construction of the Stage-I powerhouse cavern were applied on the extension of the powerhouse cavern, which is to house an additional 1000 MW. Details regarding the unexpected behaviour of the Mudstones are given. Die 1000 MW Wasserkraftanlage Masjed-e-Soleiman (vormals Godar-e-Landar genannt) befindet sich seit 1992 in Bau. Dieser Artikel berichtet im Detail über die felsbaulichen Aspekte der Untertagebauwerke, insb. der Maschinenkaverne. Die geotechnischen Untersuchungen werden beschrieben und deren Ergebnisse wie die Ergebnisse verschiedener Berechnungen werden präsentiert. Die geplante und die ausgeführte Felssicherung wird angegeben. Die eingebauten Überwachungseinrichtungen werden beschrieben und typische Ergebnisse während des Aushubs und danach werden dargestellt. Die Erfahrungen beim Aushub der Kaverne der Stufe I wurden beim Entwurf der Kaverne der Erweiterungsstufe II, die weitere 1000 MW beherbergen wird, berücksichtigt. Details zum unerwarteten Verhalten des Schluff-/Tonsteins werden angegeben. La centrale hydroélectrique de Masjed-e-Soleiman (dénommée anciennement Godar-e-Landar), d’une puissance de 1.000 MW, est en construction depuis 1992. Un rapport détaillé sera présenté sur les aspects relatifs à la construction en enrochements de l’aménagement souterrain principal, à savoir la caverne abritant la salle des machines. Une description des investigations géotechniques réalisées y est fournie ainsi que les résultats correspondants. En outre sont présentés les résultats de plusieurs analyses géotechniques. L’ancrage dans la roche tel que projeté et réalisé est présenté. Une description des systèmes de contrôle ainsi que les résultats de mesures typiques obtenus au cours des travaux d’excavation sont donnés. Les leçons tirées lors de la construction de la Phase 1 de la caverne de la salle des machines furent appliquées à l’extension de la caverne de la salle des machines, qui doit abriter une unité supplémentaire d’une puissance de 1.000 MW. Par ailleurs, des détails sont donnés sur le comportement inattendu des argilites.

Jan 1, 2003

By Joel Moskowitz

A new office complex is being constructed within 25m of the Hudson River in New Jersey. The project, about 140 m by 100 m, will include 4 basements under the entire footprint. The perimeter was to be secured by a 0.8 m thick diaphragm wall, laterally supported by high capacity tieback anchors to rock. Columns were to be supported on footings or piers to rock at a nominal bearing pressure of 3.8 MPa at depths up to 17m. Although some variation in rock quality was observed in borings, a substantial vertical seam of weathered and/or decomposed rock, 1 to 2 meters wide by as much as 8 meters deep, was encountered during construction necessitating field redesign. In some locations the seam dipped below more competent rock. Footings were redesigned for support on drilled caissons, or soft rock was excavated and replaced with concrete necessitating a reduction in bearing pressure of the footings by one half.

Jan 1, 2002

By Sam S. Taylor

Subsurface disposal of oil-field brines was practiced in Oklahoma on a limited scale as early as 1925. The technique of subsurface injection has been improved immensely and has been applied with varying success in many oil-producing areas in Oklahoma, and elsewhere. This method of disposal, however, is only one of several methods available to operators of oil-producing properties, but, in contrast with usual methods of handling brines on the surface it eliminates the damaging effect of mineralized water on fresh-water supplies, vegetation, and aquatic and other animal life. Other methods of brine disposal approved by regulatory agencies in some States include (1) impounding in impervious ponds and solar evaporation, (2) controlled diversion into surface waters, and (3) recovery of the mineral salts of the brine. In most, States where oil is produced regulatory bodies authorize the use of one or more of these methods of brine disposal. In Oklahoma, for example, the Oklahoma Planning and Resources Board of the Conservation Commission has been authorized to adopt whatever methods or means may be necessary to prevent contamination by mineralization of all potable waters within the State.

Jan 1, 1942

By Seong- Rin Lim

Light-emitting diodes (LEDs) are regarded as environmentally friendly light sources due to their high energy efficiency and lack of mercury content. LEDs are used for a variety of domestic and commercial lighting systems, where they are replacing incandescent and fluorescent lamps at a rapid rate. Incandescent lamps inefficiently consume energy because electricity is mostly converted to heat rather than light. This causes unnecessary environmental impacts and energy consumption associated with power generation and transmission from a life cycle perspective. Although fluorescent lamps are more energy-efficient than incandescent lamps, their disposal at end-of-life presents special challenges because of the presence of toxic mercury. Despite the seemingly apparent advantages of LED, very few studies have rigorously addressed potential environmental consequences of their disposal. Specifically, LEDs are designed with III-V semiconductors that presumably consist of toxic and rare materials, including arsenic, gallium, and indium. We hypothesize that, depending on their concentrations and leachability, these constituents may also contribute to render LEDs as hazardous waste at the end of their useful life.

Jan 1, 2010

By Doris M. Hyde

Mineral output and trade in the Central American countries were directly or indirectly affected by the sometimes violent civil unrest and recessionary economic developments that have pervaded the region for several years. Central American countries found their foreign exchange export earnings and traditional market areas shrinking while essential import costs were rising. Restricted spending measures were adopted by governments and private industries. Domestic investment funds for mineral development and exploration projects were among the first casualties of these austere budgetary measures, especially since weak demand and depressed mineral prices diminished the probability of a favorable cost-benefit ratio. The lack of physical security and political stability also discouraged private foreign investment. The United States Congress enacted the Caribbean Basin Economic Recovery Act of 1983 (19 U.S.C. 2702), more popularly known as the Caribbean Basin Initiative (CBI). This legislation was designed to stimulate economic recovery and promote economic development by increasing private investment and trade in the Caribbean Basin countries. The act provided for the elimination of U.S. duties on most trade items imported directly from eligible Caribbean countries, provided at least 35% of the product value originated in the region. The financial assistance components of the CBI were to be supportive of the basin's private sector as well as assist general economic stabilization programs.

Jan 1, 1985

By Charles Fried

The Coal Mine Health and Safety Act passed by Congress in 1969, called for research to alleviate the occupational stresses and hazards of coal miners. Spurred by a series of recent mine disasters the Congress directed the Bureau of Mines to increase its attention to the welfare of miners and to develop better working conditions and personal equipment for use in the mines. As one of the early steps in carrying out the provisions of the Act, the Bureau of Mines commissioned the Behavioral Sciences Group at the National Bureau of Standards to conduct a survey of the state of the art in ergonomics (human factors) as it has been applied to mining.

Jan 1, 1972

By S. Underwood

The tracer gas method of conducting ventilation surveys is a means of determining air quantity in underground mines with knowledge of the concentration of the tracer in the atmosphere and the flow rate at which the tracer is being released. The technique is useful in inaccessible areas of underground mines and areas where traditional point measurement of velocity is not practical. Sulfur hexafluoride (SF6) is the industry standard tracer(Kennedy 1987) used in underground mines because it is safe, stable, and not naturally occurring in the mine environment. The implementation of a second tracer will increase the versatility of the tracer gas technique allowing for simultaneous releases for the study of interrelated ventilation circuits, and for conducting multiple experiments in less time. This paper will detail the selection of perfluoromethylcyclohexane (PMCH) as a novel tracer with sensitivity, physical properties, and analysis characteristics similar to SF6. Methods for the release of liquid PMCH into underground mines will be recommended, and the vulnerabilities of sample loss due to condensation of vapor PMCH will be explored. Finally, the benefits and implications of using PMCH as a second tracer will be discussed.

Jan 1, 2012

By Joseph Grumer

Theory pertaining to the exchangeability of fuel gases on appliances has been extended to exchanges of propane or butane with mixtures of these. In particular, new considerations were developed bearing on the hazard of an occasional emission of carbon monoxide and flashback and blowoff possibilities. The new considerations involve using current requirements for approval of liquefied petroleum gas appliances. These requirements were used to predict allowable tolerances in chemical composition of liquefied petroleum gases for existing appliances. In addition, changes in gasline pressure were computed which may be substituted in place of fuel exchanges during testing of appliances,

Jan 1, 1962

Research by the National Institute for Occupational Safety and Health (NIOSH) on multiple-seam mining has resulted in two new ground control products. Information Circular (IC) 9495 In some U.S. coalfields, particularly in central Appalachia and the West, most mines are operating above and/or beneath previously mined seams. The effects of multiple-seam interactions can include roof falls, rib spalling, and floor heave. These can seriously threaten the safety of miners and disrupt mining operations. Information Circular (IC) 9495 is a proceedings document containing a variety of papers that summarize recent knowledge about multiple-seam mining. A NIOSH study that analyzed case histories collected from 44 U.S. coal mines is described in detail. The study confirmed that overmining is much more difficult than undermining, and isolated remnant pillars cause more problems than gob-solid boundaries. The study's results were the basis for the Analysis of Multiple-Seam Stability (AMSS) software package. The proceedings also contain two papers describing the LaModel family of software. The original three-dimensional version of LaModel is essential for detailed analyses of complex multiple-seam scenarios. LaM2D implements a simplified, two-dimensional model suitable for quick approximations of the multiple-seam stresses and strains. Three papers in the proceedings focus on case histories. One describes the extensive multiple-seam experience at the Harris No. 1 Mine in West Virginia, a second contains examples of "extreme" multiple-seam mining from the central Appalachian coalfields, and a third describes interactions with regard to longwall mine experiences in Pennsylvania, West Virginia, and Utah. The final paper reports on a numerical modeling study that provided some insight into the mechanics of multiple-seam mining. [ ] AMSS Software Package NIOSH has developed a simple, user-friendly computer program called Analysis of Multiple-Seam Stability (AMSS). AMSS can help mine planners to evaluate each potential multiple-seam interaction and take steps to reduce the risk of ground control failure. AMSS begins by evaluating the pillar design. It first calculates the single-seam pillar stability factor (SF)

Jan 11, 2007

?General Facts:Barrick?sFirst Mine in Peru Production started in November 1998 ?The Facilities:Open Pit, Primary and Secondary Crusher Valley Fill Heap Leach PadMerrill Crowe PlantRefinery Environmental Facts: High Rainfall - Average Annual Precipitation of 1,200 mm (47 inches) Rainfall Events: Common 20mm daily events High Altitude Site - Elevations range from 3900 to 4250m. Steep topography - Terrain ranges from 3:1 slopes up to cliffs. Water Issues: Sediment Control - Open Pit PAG Encapsulation - Waste Dump Stormwater control - Leach Pad Erosion Control Techniques ? Offsite impacts mitigation Social Issues: 11 communities surrounding the property Town of Huaraz

May 1, 2003