Search Documents

By Sang Bum Chi

In order to better predict and manage benthic disturbance by deep seabed manganese nodules mining, we needed to conduct a benthic disturbance experiment at the selected area, which has a similar environmental condition as the preservation reference area. Therefore, we have performed environmental baseline studies from 2003--not only to select the benthic environmental impact testing site but, also to detect any environmental changes before and after mining activity. Since then, a large dataset of various parameters ranging from physical (e.g. temperature, salinity, current, weather), chemical (e.g. dissolved oxygen, nutrients, dissolved and particulate organic carbon), biological (e.g. bacteria, plankton, benthos), geological (e.g. Mn-nodule abundance, sediment shear strength) and others (e.g. bathymetric profile and slope, mass flux) have been accumulated. Using this dataset, descriptive statistics and cross-correlations were performed to select the benthic environmental impact testing site. Outcome of this analysis suggests that the potential benthic impact testing site would be a rectangular-shape area (10 km × 10 km) and located at 10°27'~10°33'N, 131°53'~131°58'W, which is latitudinally the same as the preservation reference area.

Jan 1, 2011

By R. R. Sayers

VENTILATION may be defined as the process by which vitiated air of an inclosed or partly inclosed space is continuously replaced by fresh air. Fresh air has been defined as invigorating pure air. Pure dry air at sea level contains the following gases:1 Analysis of Air at Sea Level PER CENT. Oxygen 20.94 Nitrogen 78.09 Carbon dioxide 0.03 Argon 0.94 Helium, krypton, neon, xenon, hydrogen, hydrogen peroxid, ammonia, ozone traces CARBON DIOXIDE LIMIT For many years carbon dioxide was used as an index of the purity of the air vitiated by the metabolism of people. It was, however, well known that the untoward effects produced on those exposed to such air was not due to the concentration of the carbon dioxide. It has been found that the untoward effects on the comfort and efficiency of those so exposed are due to the increased temperature and humidity. It has been found that men can breathe air containing many times the amount of carbon dioxide found in our worst ventilated theaters and assembly halls, which, according to Rosenau, do not contain above 0.5 per cent. carbon dioxide.

Jan 7, 1926

By Vijia K. Karra, John J. Sammarco, Robert Paddock, Edward F. Fries

Workers in hazardous environments such as mining are constantly exposed to the health and safety hazards of dynamic and unpredictable conditions. One approach to enable them to manage these hazards is to provide them with situational awareness: real-time data (environ-mental, physiological, and physical location data) obtained from wireless, wearable, smart sensor technologies deployed at the work area. The scope of this approach is limited to managing the hazards of the immediate work area for prevention purposes; it does not include technologies needed after a disaster. Three critical technologies emerge and converge to support this technical approach: smart-wearable sensors, wireless sensor networks, and low-power embedded computing. The major focus of this report is on smart sensors and wireless sensor networks. Wireless networks form the infrastructure to support the realization of situational awareness; therefore, there is a significant focus on wireless networks. Lastly, the “Future Research” section pulls together the three critical technologies by proposing applications that are relevant to mining. The applications are injured miner (person-down) detection; a wireless, wearable remote viewer; and an ultrawide band smart environment that enables localization and tracking of humans and resources. The smart environment could provide location data, physiological data, and communications (video, photos, graphical images, audio, and text messages).

Jan 4, 2007

"This paper deals with the reconciliation of open stope performance at Olympic Dam, South Australia, with a focus on stope stability, recovery, and operational aspects of stope reconciliation in relation to the expected or planned stope design. The observed stope performance is inconsistent with the equivalent linear overbreak sloughing criteria for assessing the performance of large open stopes. The aim is to investigate new stope performance criteria using quantitative (overbreak, underbreak, maximum depth of wall failure) and qualitative (stope productivity, observed fragmentation) information that correlates with the observed stope behaviour, providing a process for improving future stope designs.RÉSUMÉ Le présent article traite de la réconciliation de la performance des chambres ouvertes à Olympic Dam, Australie du Sud, en ciblant la stabilité des chambres, la récupération et les aspects opérationnels de la réconciliation des chambres par rapport à la conception attendue ou planifiée des chambres. La performance observée des chambres ne concorde pas avec les critères d’épaisseur équivalente du bris hors profil pour évaluer la performance de grandes chambres ouvertes. L’objectif est d’étudier de nouveaux critères de performance des chambres au moyen de données quantitatives (rupture hors profil, rupture à l’intérieur du profil planifié, profondeur maximale d’effondrement du mur) et qualitatives (productivité de la chambre, fragmentation observée) qui concordent avec le comportement observé des chambres, fournissant ainsi un processus pour améliorer les futures conceptions des chambres."

Jan 1, 2015

By Robert L. Greyer, John I. Myung

The Birdwell 3-D Velocity Log displays photographically the amplitude of elastic waves as a function of time and of the depth of the logging tool in a borehole. The elastic waves are generated by a magneto-strictive source transducer and detected by a receiving transducer, which is at a fixed distance from the source. The output of the receiver, which is proportional to the amplitude of the received elastic waves, modulates the light that exposes the film record. The duration of the receiving time can be selected to record the entire wavetrain of late events or to record only early events at a finer time scale. When a full complement of elastic waves (i.e., the refracted compressional wave, composite shear wave, direct fluid wave, and boundary wave) is recorded, their velocities and the density of the borehole fluid provide the information necessary to compute the elastic moduli and density of the rock surrounding the bore-hole. The differences between the values of the moduli determined from measurements of 3-D Velocity Logs and by other better known techniques are small, well within the limits of experimental error, when the velocity log is interpreted by an experienced seismic analyst. INTRODUCTION Quantitative descriptions of the mechanical properties of the rock environment have long been basic requirements of planning, design, and quality control of engineering projects. Because of this need, many techniques for determining the elastic moduli from static and

Jan 1, 1971

A well known rock mass classification system has been altered slightly to address the issues found under remnant mining conditions. By detail study of the expected fracture patterns and local geology, the rock mass is classified to indicate the condition of the hanging wall prior to mining. The risk level of each mining step is evaluated by calculating input parameters for computer simulations from the actual rock mass condition. Seismic activity is catered for by the understanding that large event rates and large magnitude events reduce the quality of the local rock mass and that the rock mass stiffness should be adapted accordingly. A case study is presented to test parts of the protocol. Un système connu de classification des masses rocheuses a été légèrement modifié pour faire face aux questions posées par les conditions d’extraction de débris. Une étude détaillée des diagrammes de fragmentation et de la géologie locale permet de classer la masse rocheuse pour indiquer la condition du toit avant l’extraction. Le niveau de risque de chaque étape minière est évalué en calculant les paramètres d’entrée pour simulation par ordinateur à partir de la condition réelle de la masse rocheuse. L’activité sismique est prise en compte avec la réalisation que les taux de larges évènements et les évènements de large magnitude réduisent la qualité de la masse rocheuse locale et que la raideur de la masse rocheuse doit donc être adaptée. Une étude de cas est présentée pour tester des sections du protocole. Ein sehr bekanntes Gesteinsmassenklassifikationssystem wurde abgeändert um die Probleme zu behandeln die unter Restabbaukonditionen angetroffen werden. Durch detaillierstes Studium der der zu erwartenden Bruchmuster und der lokalen geologischen Verhältnisse wird die Gesteinsmasse in Hinblick auf die Konditionen der Flözoberseite klassifiziert. Das Risikoniveau für jeden Abbauschritt wird durch die Eingabeparameter aktuellen Gesteinsmassenkondition für die Computersimulation evaluiert. Für die Seismische Aktivitäten wird Sorge getragen durch das Verständnis, daß große Ereignisraten und Ereignisse hoher Größenklassen die Qualität der lokalen Gesteinsmasse reduzieren und daß die Gesteinsmassensteifheit entsprechend adaptiert werden sollte. Eine Fallstudie um Teile des Protokolls zu testen wird präsentiert.

Jan 1, 2003

By D Porta, E Grigolato, K Behrens

################

Aug 12, 2013

By J. J. Demeter

As part of its work on converting coal to fluid fuels, the Federal Bureau of Mines has been studying the synthesis of liquid fuels from carbon monoxide and hydrogen by Fischer-Tropsch synthesis. A fluidized bed of nitrided, fused-iron catalyst has been operated successfully to produce high yields of oxygenated compounds. Trouble-free operation continued for over 800 hours, and the test was terminated voluntarily. About 85 percent of the fresh feed was converted when the unit was operated at a space velocity of 500 hr.-1, a 12:1 recycle-to-fresh-feed-gas ratio, a 300-p. s. i. g. pressure, and a temperature of 252° C. When operating at a fresh-feed-gas space velocity of 1,000 hr.-l and a 9:1 ratio of recycle to fresh gas, conversion of fresh feed was 68 percent, and the product yield was 235.9 grams per cubic meter of synthesis gas converted. The oxygenate and C5 and heavier hydrocarbon yield was 110.6 grams per cubic meter of gas converted, 83 percent of this was oxygenates. The atom ratio of N:Fe of the catalyst, initially 0.455, decreased to 0.288 by the end of the 800-hour experiment. Nevertheless, the yield of oxygenated compounds per cubic meter of H2 + CO converted at the end of the run was approximately the same as that obtained 500 hours earlier with identical operating conditions. X-ray analysis of the discharged catalyst indicated that only ?-iron carbonitride was present. Sieve analysis of the discharged catalyst indicated that only 2 percent of fines was produced during the reduction, nitriding, and synthesis.

Jan 1, 1959

By T. M. Yegulalp

A numerical model is being developed to assess the enhancement of permeability by improved fracture connectivity by micro-hydrofracturing. A generic two-dimensional percolation model has been developed to test the impact of various field conditions on permeability. Field data from Cyprus Minerals' Mineral Park Mine has been used to establish statistical properties of the observed fracture systems. Results of statistical anlyses of the field data and examples of the use of percolation model are presented.

Jan 1, 1995

By D. Newman

Ground control is critical to the success of a safe and productive underground stone mining operation. The primary focus of the ground control engineer is the stability of the roof or back; development and benched pillar stability; stability of the sill pillar between vertically adjacent mining levels; and floor stability. Roof stability begins with the selection of a stable back horizon based on the presence of a thin shale parting, stylolite or other discontinuity from which the production shot can easily peel away, leaving a stable back stratum. Bed thickness, fracture spacing, jointing and the material properties of the roof strata control the room width; the decision whether to bolt the roof; the bolt length, type and diameter; and the spacing of the roof support. Horizontal stress controls the header and crosscut azimuth. The mine operator should avoid driving perpendicular to the maximum horizontal stress direction. Where this is unavoidable, narrowing the opening width, narrowing pillar centers, increasing the support density and using three-way intersections are alternatives to remediate shearing along the roof-rib interface. Stable pillar dimensions depend upon the interaction of the vertical stress resulting from overburden thickness and multiple-level interaction of overlying level or levels; the mining height during development and the final mining height after floor shots are taken during benching; the presence of faults, folds or joints passing through the pillar; and limestone lithology, recognizing that the presence of oolitic bands, shale partings, joints and bentonite beds creates zones of weakness that can destabilize an otherwise competent pillar. Floor stability is typically not a significant issue for underground stone mines because the bearing capacity of the stone typically exceeds the vertical pressure transferred through the pillar. However, floor heave can be a ground control issue where shale partings, moisture-sensitive strata, weak stone bands or horizontal stress is present. Roof stability and pillar stability problems can be initiated as the floor heave enables the pillar and roof to settle. To illustrate these ground control issues, this paper presents four case histories that are a mix of ground failures and successful mining. The focus is on the geotechnical data required for roof, pillar and floor design and stability analysis.

Jan 8, 2017

By M. G. Hester

The ore reserve modeling of stratiform uranium deposits to be mined by selective underground mining methods must be done with consideration of the erratic nature of the ore forming processes that produced the mineralization. Estimation methods that model the uranium grade as a smooth transition between high grade and low grade drillhole intercepts tend to greatly overestimate the ore tonnage. Care must be taken to first establish realistic ore pod geometries and then estimate the grade of the reserve units within the pods.

Jan 1, 1985

By W. R. Hopkins

Over 95 percent of the world's refined copper is now produced by electrolytic processes. The bulk of this electrolytic copper comes via the conventional route for sulfide ores of concentration, smelting and electro-refining. A rapidly increasing percentage of world production is now achieved using hydrometallurgical routes involving dissolution of the copper values from minerals, purification of the resultant leach solution by solvent extraction and finally deposition as cathodes by electrowinning. The technology can now be considered mature and this paper endeavors to summarize recent developments which, from the authors' perspectives, are important.

Jan 1, 1989

By Dominique Francois-Bongarcon

The world mining industry is facing a severe recession. Thus, it is time to recall the value of geostatistical methods which were formerly developed as a money-saving and productivity-increasing tool. The situation has worsened, but the techniques of geostatistics have dramatically changed. Up to millions of dollars can be saved during exploration with simple use of variograms; then, during reserves estimation with kriging methods; and finally, with the parameterization of reserves, when evaluating a project and optimizing its global mining parameters.

Jan 1, 1983

By Robert S. Penczak

Red Lake Gold Deposits ? Descriptive Classification (modified from Pirie, 1982) VHR Au -- Volcanic-hosted (vein & wall-rock) replacement Au deposits ~93% of camp production Q-(T) Au -- Quartz-(tourmaline) vein Au deposits ~7% of camp production Quartz-sulphide Au deposits Porphyry-hosted sulphide Au deposits Current & Significant Past Producers Camp Production 21.6 M oz / 672 tonnes Au Other Deposits / Occurrences (Intermittent Exploration

Apr 1, 2005

[ ]

Jan 1, 1942

By Antonio S. Aldana Selders

With special designed explosive and a system to lower down a heavy load of Explosives through 8" pipe results are achieved, the stimulation of sulphur production takes place. Well # 18-1063 at 515 meters below ground is loaded with 802 units of explosives with total weight of 1820 kilos to fill up the column of 93 meters of limestone & sulphur strata.

Jan 1, 1995

By Walter G. Perkins

As this particular product holds a place by itself, it seems desirable to give a paper dealing especially with it as a corollary to my paper entitled " The Litharge Process of Assaying Copper-Bearing Ores and Products, and the Method of Calculating Charges."* The process is first to convert the metallic copper into matte by the addition of sulphur, allowing the two elements to combine at the bottom of the crucible when heat is applied. The

Jan 1, 1903

By Charles A. Schffer

Several months ago, some specimens of the minerals occurring at the Etta tin mine, Dakota, were received at the laboratory of the Cornell University. On examining the heavy brownish-black portion, which I presumed was the tin-stone, I was surprised to find only a faint indication of tin. Further investigation showed the mineral to be tantalite. On searching carefully all the fragments received, a considerable quantity of that mineral was found, and only a single streak of cassiterite, which was attached to a mass of spodumene. Another lot of specimens, from the same locality, consisted of

Jan 1, 1885

By G. Récoché

For the African continent promoting a sustainable utilization of its mineral resources could be considered as a key determinant to fight against poverty. Sustainable development performance indicators for measuring the economic, environmental and social impacts of mining activity are necessary for drawing up policies and sectoral actions, identifying and controlling risks, identifying and implementing sustainable development actions, negotiating between stake-holders, improving mine production, etc. To respond to this need, the SIGAfrique Network proposed to develop a joint decision support tool entitled the African Mining Observatory (AMO) and, to this end, develops a system of indicators to be integrated within the SIGAfrique database. The development of both the OMA and the indicators is based on a participatory method within the working groups, which comprise experts/participants from the 13 SIGAfrique partner and observer countries (Guinea, Burkina Faso, Mali, Tanzania, Niger, Mozambique, Kenya, Uganda, Senegal, Angola, Madagascar, Ethiopia, and Mauritania).

Jan 1, 2007

By P. Michalcik, V. Petros, M. N. Bagde, K. Holub

The objective of this paper is to present some results of laboratory experiments during the investigation of stress-strain characteristics of Carboniferous sandstones at dynamic loading. During these experiments increasing frequency and the constant amplitude of dynamic loading and/or constant frequency at different amplitude of dynamic loading were applied. Der Gegenstand dieses Artikels ist, irgendeine von Ergebnissen von Laborexperimenten bei Messung der Spannungs- und Deformationscharakteristik der Karbonsandsteine bei ihrer dynamischen Belastung vorzustellen. Im Laufe diesen Experimenten wurden entweder anwachsende Frequenzen bei konstanter Amplitude der dynamischen Belastung, oder gleiche Frequenzen bei variabler Amplitude der dynamischen Belastung verwendet. L'objectif de ce papier est présenter quelques résultats d'expériences de laboratoire pendant l'enquête de caractéristiques de la tension – deformation de grès Carbonifère à sollicitation dynamique. Pendant ces expériences fréquence croissante et l'amplitude constante de sollicitation dynamique et/ou fréquence de la constante à amplitude différente de sollicitation dynamique ont été appliquées.

Jan 1, 2003