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By L. Li

The performance of microemulsified diesel and conventional diesel collectors in coal flotation was compared by flotation indicators, including combustible recovery, ash content of the clean coal, and the flotation index. An efficient separation with lower dosage was obtained using the microemulsified diesel collector. Under optimum separation conditions, the microemulsion consumption was 100 g/t less compared with diesel. The saving in diesel consumption using the microemulsion reached about 70%, disregarding the consumption of the surfactant and cosurfactant. Frothing tests showed that the frother dosage was decreased by using the microemulsion collector, because of the surfactant and cosurfactant added during preparation. The microemulsified diesel collector is superior to the conventional diesel collector in terms of diesel consumption and separation efficiency, but the selectivity requires further improvement. Keywords froth flotation, microemulsified collector, coal.

Nov 1, 2013

By M. K. Elmouttie, G. V. Poropat

The analysis of structure using joint set statistics is well known. Other data such as the position of discontinuities and the contacts between rock mass units cannot be easily incorporated in simple statistical analysis based on orientation alone. Algorithms to model the structure of rock slopes using measurements of the orientation and position of discontinuities are being developed by CSIRO Exploration and Mining. These algorithms provide a capability to model the structure of a rock slope and estimate the likelihood of the formation of hazardous blocks in existing or proposed rock slopes and identification of the location and size of these blocks. The algorithms provide the basis of structural modelling to identify potential failure mechanisms in rock slopes.

Jan 1, 2006

Instability in rockpasses at deep levels often initiates as a result of stress induced fracturing of the rock on the walls of the pass. This may then progress to a stage at which the geological structure of the rock mass becomes dominant and permits large joint-defined blocks and slabs to become unstable. In this paper, a technique is described in which jointing parameters and their variabilities?orientations, spacings and lengths?are taken into account in estimating the extent of failure that may develop around a typical unsupported deep level gold mine rockpass. The results of this prediction are compared with the results obtained from a review of pass performance in the gold mining industry.

Jan 1, 2005

By F. H. Cornet, D. Ask, O. Stephansson

We have conducted a stress analysis of overcoring stress measurements undertaken at the Zedex Test Site (ZTS) in the Äspö HRL, Sweden. Two different types of overcoring cells have been used at the site: the 9-gauge Borre Probe (CSIR-type) and the 12-gauge CSIRO HI cell. Inversion programs based on the least-squares criterion were developed and calibrated. The primary and secondary stress field in the ZTS were back-calculated using strain data from individual cells as well as from combining data from both cells. We propose that the combination of strain data from the two cells significantly improves the determination of the stress field. A striking result is the good agreement between the re-analysed overcoring data and the existing hydraulic fracturing data. The deviations for the horizontal stresses between the re-analyzed overcoring data and the existing hydraulic fracturing data are approximately 3 MPa. The deviation in the orientation of maximum horizontal stress is approximately 10-20°. Nous avons analysé les résultats de mesures de contrainte par surcarottage réalisées sur le site Zedex, du laboratoire souterrain HRL d’Aspö, en suède. Deux types de cellule de mesure ont été utilisés sur ce site : la cellule à 9 jauges (du type CSIR) et la cellule à 12 jauges (du type CSIRO HI). Un programme d’inversion mettant en œuvre une norme par moindres carrés a été développé et validé. Les champs de contrainte primaires et secondaires du site Zedex ont été évalués d’une part en considérant chaque mesure isolément, d’autre part en intégrant l’ensemble des données de déformation dans une inversion unique. Nos résultats suggèrent que l‘association des diverses mesures dans une intégration unique améliore nettement la détermination du champ de contrainte. Un résultat intéressant est le bon accord entre ces nouveaux résultats et les résultats des mesures par fracturation hydraulique. Les écarts sur l’amplitude des contraintes horizontales est de l’ordre de 3 Mpa, les écarts sur les orientations de l’ordre de 10-20°. Auf dem Zedex Test Gelände im Äspö Festgesteinslabor (HRL) wurde eine Spannungsanalyse mittels Overcoring Spannungsmessungen durchgeführt. Hierzu wurden zwei verschiedene Methoden verwendet: das 9-kanal Borre Gerät (CSIR- Ausführung) und die 12-Kanal CSIRO HI Zelle. Inversionsprogramme, die auf dem “least-squares”- Kriterium basieren, wurden entwickelt und kalibriert. Das primäre und sekundäre Spannungsfeld des Zedex Test Geländes wurde sowohl aus Verformungsdaten individueller Zellen als auch aus Kombination beider Zellen ermittelt. Wir nehmen an, daß die Kombination der Messergebnisse beider Geräte die Bestimmung des Spannungsfeldes signifikant verbessert. Überzeugender Beweis hierfür ist die gute Übereinstimmung der überprüften Overcoring Daten und Ergebnisse aus existierenden Hydraulic Fracturing Versuchen. Die Abweichungen der horizontalen Spannungen aus beiden Datensätzen ist etwa 3 MPa und Abweichungen der Orientierung der größten Horizontalspannung liegen bei etwa 10-20°.

Jan 1, 2003

1. A statistical approach to some mine valuation and allied problems on the Witwatersrand. Unpublished Master?s Thesis, University of the Witwatersrand ? 1951. (Separate) 2. A statistical approach to some basic mine valuation problems on the Witwatersrand - J. of the Chem. Metall. and Min. Soc. of S.A., December, 1951 - discussions and replies March, May, July and August 1952. (Vol. 1?.1). Also: J. of the Institute of Mine Surveyors of S.A. December 1952, March 1953. (Vol. 1?2) 3. A statistical analysis of some of the borehole values of the Orange Free State goldfield - J. of the Chem. Metall. and Min. Soc. of S.A., September, 1952 - discussions and reply November 1952, and February 1953. (Vol. 1?3). 4. A study of the relationship between development values and recovery grades on the South African goldfields - J.S.A.I.M.M, January 1959, - discussion and reply April and October 1959. (Vol. 1?6) 5. On the departure of ore value distributions from the lognormal model in South African gold mines. J.S.A.I.M.M., November 1960, January and August 1961. (Vol. 1?8) 6. Developments in the valuation of gold mining properties from borehole results - Seventh Commonwealth Mining and Metallurgical Congress, 1961. (Vol. 1?9) 7. Effective pay limits for selective mining. J.S.A.I.M.M., January and August 1962. (Vol. 1?10)

Jan 1, 2014

By Ch. Schroeder, F. Collin, R. Charlier, Y. J. Cui

The paper proposes two numerical models ot the mechanical behaviour of chalk. First, an elasto-plastic constitutive law reproduces the different plastic mechanisms of the chalk and the influence of pore fluids by introducing the concept of suction. Secondly, a model able to reproduce time dependence behaviour. Eventually, the paper gives a simulation of an academic reservoir during depletion and waterflooding phase. Der Artikel stellt zwei numerische Modelle des mechanischen Verhaltens der Kreide vor. Das erste ist ein elasto-plastisches Modell, das verschiedene plastische Mechanismen der Kreide und den Einfluss von Porenflüssigkeit, unter dem Begriff der Suktion, reproduziert. Das zweite Modell berücksichtigt darüberhinaus das zeitabhängige Verhalten. Schliesslich zeigt die Veröffentlichung eine Simulation einer theoretischen Lagerstätte während der Entleerung und der Wasserinjektion. L'article propose deux modèles numériques du comportement mécanique de la craie. Le premier est une loi élasto-plastique qui reproduit les différents mécanismes plastiques de la craie et l'influence du fluide interstitiel par l'introduction de la notion de succion. Le second est un modèle prenant en compte les effets différés. Enfin, l'article présente une simulation d'un réservoir académique durant les phases de déplétion et d'injection d'eau.

Jan 1, 2003

By M. F. Handley

Sequential grid mining has been employed as the primary mining strategy at the AngloGold West Wits Elandsrand Mine since the inception of stoping operations from the sub-vertical shaft system in 1988. Little has been published on sequential grid mining as a mining strategy since, and the purpose of this paper is to describe sequential grid mining, its history, its implementation at Elandsrand, and the outcome to date. The results obtained using sequential grid mining have been evaluated from seismic data, productivity statistics, and rock related accident statistics. Comparisons with neighbouring mines namely Western Deep Levels and Deelkraal, have been made to substantiate the improved conditions observed at Elandsrand, and to compare sequential grid mining directly with longwall mining in similar conditions and at similar depths. Sequential grid mMining is shown to be cost-effective, more flexible, and safer than long wall mining in similar conditions, at least on the Ventersdorp Contact Reef in the western part of the Carletonville Goldfield. More work is necessary to establish it as the favoured mining strategy at depths exceeding 3000 metres, and for reefs other than the Ventersdorp Contact Reef.

Jan 1, 2000

By Marco Barla, Mariacristina Bonini, Giovanni Barla

ABSTRACT: The paper describes the characterisation studies of Tectonised Clay Shales at laboratory and in situ scale. The interest relates to tunnelling under squeezing and swelling conditions, in Italy, along the Apennines. The results of monitoring during full face excavation are presented in conjunction with numerical modelling. RESUME: Cet article présente la caractérisation, à l'échelle du laboratoire et in situ, des Argiles Chaotiques. L'attention est portée sur le creusement, dans ces milieux gonflants, des tunnels, dans les zones montagneuses des Appennini, en Italie. Enfin, on présentera les résultats de la modélisation numérique et la comparaison de ces derniers avec les mesures effectuées in situ. KURZFASSUNG: Die Arbeit beschreibt die Charakterisierungsstudien von tektonisierten Schiefertonen, sowohl im Labor als auch vor Ort. Das Interesse gilt dem Tunnelbau unter Quetsch- und Schwellbedingungen in Italien entlang der Apenninen. Die Überwachungsergebnisse des ganzflächigen Ausbruchs werden mit numerischen Modellen präsentiert.

Jan 1, 2003

By C. Erichsen, J. Werfling

ABSTRACT: A three-dimensional elastic constitutive model for rock salt is proposed. This stress strain law takes into account the three phases of creep (transient, steady state and accelerated creep), dilatancy, as well as the failure and post failure behaviour. The model was implemented into a finite element program and validated on the results of laboratory tests and in situ measurements. A good qualitative and quantitative agreement with the test and measurement results is achieved. A stability analysis for an underground repository in rock salt is presented. ZUSAMMENFASSUNG: Es wird ein dreidimensionales elastisch-viskoplastisches Stoffgesetz für Steinsalz vorgestellt. Mit diesem Stoffgesetz können die drei Kriechphasen (primäres, sekundäres und tertiäres Kriechen), Dilatanz sowie das Bruch- und Nachbruchverhalten erfaßt werden. Dieses Modell wurde in ein Rechenprogramm, das auf der Methode der finiten Elemente basiert, implementiert und an Ergebnissen von Laborversuchen und in-situ-Messungen validiert. Die Versuchs- und Meßergebnisse lassen sich mit diesem Stoffgesetz qualitativ und quantitativ gut nachvollziehen. Als Anwendungsbeispiel wird der Standsicherheitsnachweis für eine Untertagedeponie im Steinsalz erläutert. RÉSUMÉ: Cet article présente un modéle constitutive élastique/viscoplastique à trois dimensions pour sel gemme. Ce modéle comprend les trois stade de fluage (fluage primaire, secondaire et tertiaire), la dilatation, le comportement de défaillance et d'après défaillance. Il est implanté dans un programme de calcul aux éléments finis. À l'aide des essais laboratoire et des mésures in situ, le modéle a été validé. Les résultats des essais et des mesures concordent qualitatifs et quantitatifs aux résultats des calculations.

Jan 1, 2003

By Jeffrey C. Hillman

The need to recruit locally produced engineers by the South African Mining Industry led to the Engineering Faculty at the University of the Witwatersrand developing a number of academic bridging initiatives for educationally disadvantaged students. The graduation rate achieved during the initial five years of operation by the most successful of these programmes has been on a par with that of al other students but the performance of subsequent intakes has declined to such an extent that the continuance of this scheme could now be at risk. One reason for this reduction in throughput is that many of the applicants for the increasing number of mining bursaries have been more interested in the bursary than the profession and have either failed or dropped out due to a lack of application and motivation. This will have serious consequences for both Wits and the Industry if it continues and some method of identifying unsuitable or suspect applicants needs to be introduced as a mater of urgency. It is recommended that an introductory course be set up at a working mine that would be run under the auspices of Wits, as a joint venture with industry, and include a level of academic input that would provide both bridging needs and certain first year credits. The final form of this course will require extensive consultation with al parties but needs to be completed before the end of 1996. It is further recommended that the advertising and promotion of mining careers be expanded and much improved.

Jan 1, 1996

By D. E. Ng?andu

The experience of Mufulira concentrator, of the Zambia Consolidated Copper Mines Limited, with underground mine drainage water, which is used in milling operations is discussed. It is shown that the underground mine water has a deleterious effect on flotation performance. The adverse effect of the underground water was successfully negated by adding lime into the primary ball mills and increasing the pH of the slurry, from a ?natural? pH of 8 to the flotation pH of 10.5. Traditionally, the pH modifier, quicklime, had been added downstream of the milling. Changing the lime addition point further reduced lime consumption by 50%,?a key issue as lime accounted for over 60% of the Mufulira flotation reagent costs. The nature of the effect of the underground water at Mufulira, particularly the sensitivity of the flotation to the pH at which the milling was conducted, characterized galvanic interaction. A large-scale plant situation is presented in which the desired electro-chemical response in the flotation was achieved, by a deliberate manipulation of the milling environment. The experience provides practical testimony of a more fundamental role for the milling process, other than the mere physical preparation, i.e. size reduction and liberation, of mineral particles prior to flotation.

Jan 1, 2001

By A. A. Smithen

There is an increasing awareness of the importance of including an assessment of environmental liabilities in the preparation of bankable feasibility documents. This means that environmental assessments of proposed, existing and decommissioned mine sites have to be undertaken for the purposes of quantifying environmental liabilities and assessing potential risks. This paper examines the need for considering environmental liabilities before describing the approach adopted in undertaking due diligence studies for the preparation of bankable feasibility documents and some of the difficulties experienced. Finally, some concluding remarks are made and the implications for the mining industry are discussed.

Jan 1, 1999

The aim of this research was to study the absorption characteristics of thermally dried fine coal from South African collieries. After milling to ?150 µm and pressure filtration, the samples were subjected to either air drying or thermal drying at 150°C. The samples were then put into a climate box at 28°C and at three different relative humidity levels, namely 30, 60 and 94 per cent. It was found that the equilibrium moisture content of thermally dried coal at a specific relative humidity was lower than that of air dried coal. The relationship between the equilibrium moisture content and relative humidity is described by 1 ? RH = exp (-KTMen). There was no relationship between the volatile matter content and equilibrium moisture content, but there was an increase in the equilibrium moisture content of the coal with an increase in mineral content. The moisture uptake rate increased with an increase in temperature and a decrease in particle size. A model is discussed that fitted the experimental data and gave a good prediction for changes in the conditions. There was no evidence of greater moisture absorption by thermally dried coal. Keywords: Fine coal, thermal drying, drainage, South Africa, drying

Jan 1, 2002

By J. P. Harrison

ABSTRACT: The significant effect of fracture surface morphology on the mechanical behaviour of rock masses is well known and has been studied by many people. For linear profiles taken from fracture surfaces, short- and long-period variation has traditionally been described using the descriptors ‘roughness’ and ‘waviness’, with Fourier series analysis being perhaps the most commonly used technique to distinguish between the two attributes. However, the mathematical procedure is involved and the assumptions that have to be made may not be appropriate for rock fracture surfaces. In this paper, an alternative method is presented that enables us to distinguish between roughness and waviness of a linear profile by performing only one straightforward analysis. In our technique, surface morphology is studied in terms of the distribution of unit normal vectors to the profile. The statistical analysis of the distribution is performed using Riemannian, rather than the customary Euclidean, geometry, and from this the 1D Riemannian dispersion parameter (DR1) is obtained, which quantifies the geometry of the profile. The method is applied at different scales to both synthetic sinusoidal profiles and real rock profiles. The results show how periodic behaviour of the profile is revealed at scales where DR1 is substantially equal to zero. RESUME: L’influence significative de la morphologie des épontes sur le comportement mécanique des massifs rocheux est bien connue et a fait l’objet de nombreuses études. Pour les profils lineraires, les variations de courtes et longues périodes sont traditionnellement décrites par les indicateurs “rugosité” et “ondulation” qui sont le plus couramment distingués à l’aide d’une analyse en series de Fourrier. Cependant, la méthode de calcul utilisée et les hypothèses faites ne sont pas appropriées dans le cas des épontes rocheuses. Cet article présente une méthode alternative qui permet de distinguer la rugosité de l’ondulation d’un profil en réalisant une seule analyse directe. Avec notre technique, la morphologie de l’éponte est étudiée comme une distribution spatiale de vecteurs normaux au profil. L’analyse de cette distribution est réalisée à l’aide de la géométrie Riemannienne plutôt que la géométrie classique Euclidienne et permet d’identifier la dispersion Riemanienne en 1D (DR1) qui quantifie la géométrie du profil. Cette méthode est appliquée à différentes échelles sur des profils artificiels sinusoïdaux et des épontes naturelles. Les résultats montrent que le comportement périodique du profil est révélé à des échelles où DR1 est essentiellement égal à zéro. ZUSAMMENFASSUNG: Der signifikante Effekt von Bruchoberflaechen Morphologien auf das mechanische Verhalten von Gesteinsmassen ist gut bekannt und von vielen Bearbeitern untersucht worden. Traditionel lineare Profile von Bruchflaechen sind mit kurz und lang periodischen Variationen, die auch als “Rauhigkeit” und “Welligkeit” bezeichnet worden sind, beschrieben worden. Hierbei ist wohl die Fourier Serien Analyse das wichtigste Hilfsmittel zur Unterscheidung der beiden Attribute gewesen. Hierfuer wird jedoch ein mathematisches Prozedere verlangt und Vorraussetzungen gemacht, die vielleicht nicht fuer Gesteinsbruchflaechen zutreffend sind. In dieser Publikation wird eine andere Methode vorgestellt, die uns mit Hilfe nur einer einfachen Analyse erlaubt zwischen “Rauigkeit” und “Welligkeit” bei einem linearen Profil zu unterscheiden. In unserer Methode wird die Gesteinsoberflaeche unter zu Hilfenahme der Verteilung von Einheitsnormalvektoren beschrieben. Die statistische Analyse der raeumlichenVerteilung dieser Vektoren wird mit Hilfe der Riemannschen, anstatt der ueblicherweise benutzten Euklidischen, Geometrie durchgefuehrt. Von ihr wird der Riemannsche Dispersions Parameter (DR1) abgeleitet, der die Geometrie des Profils quantifiziert. Diese Methode ist bei verschiedenen Masstaeben sowohl auf rein harmonische (sinusoidale), syntetische Profile als auch auf Gesteinsprofile angewendet worden. Die Ergebnisse zeigen, dass bei Masstaeben bei denen DR1 nahe Null ist periodische Characteristika der Profile hervortreten.

Jan 1, 2003

By W. Kint

More than 10 years ago, one of MECS?s current partners KVT developed the so called SULFOX process for cleaning waste gases containing sulfuric compounds. In this Wet Acid Process (WAP) compounds such as SO2 and H2S, CS2, COS are oxidized over catalyst bed(s) to SO3 and finally sulfuric acid is formed. The individual plants are designed according the feed gas concentrations and customers requirements to keep the investment and operating costs as low as possible. MECS strongly believes the technology we propose will meet all your expectations. Thanks to our vast experience in the construction of sulfuric acid plants (MECS built over 800 sulfuric acid plants worldwide) we were able to design you a very reliable installation. MECS is offering the metallurgical industry, besides our conventional acid plant technology (for strong SO2) and our DynaWave? scrubbing technology (for very low SO2), a SULFOX wet acid plant (for the mid range SO2 concentrations) including an optional upstream DynaWave gas cleaning plant if required. See the figure below. Besides providing advanced technology, MECS is the only company who designs and manufactures its own key critical equipment. We manufacture our own catalyst, mist eliminators, acid distributors and coolers. Because of our in-depth technology knowledge, we understand the critical aspects necessary for making optimum equipment designs. With this combined supply of technology and key critical equipment, we can make a single overall guarantee second to none other in the world.

Jan 1, 2009

Open cast mining has been practiced in South Africa since the late1970s under near ideal geotechnical conditions. In the past decade, with the exhaustion of the traditional South African coal fields, geotechnical conditions have deteriorated. In addition, the nature of the open cast coal mining industry is changing from the conventional strip mining of virgin coal seams to the extraction of underground coal pillars by buffer blasted highwalls. These industry changes have resulted in the need to re-examine the manner in which geotechnical engineering is applied to highwall design. This paper proposes a geotechnical design rationale for open cast highwalls. Furthermore, the rationale takes cognizance of the various geotechnical hazards associated with conventional strip mining and pillar extraction by buffer blasted highwalls. The need to use geotechnical domain models and blasting geotechnics, as proactive tools for rock fall reduction, are also discussed.

Jan 1, 2001

By A. Burger Pintér

To be meaningful the sharing of ideas about the National Environmental Management Act (NEMA) and social issues within the context of Mining and Metallurgy (M&M) requires an honest scrutiny of the M&M/social environment relationship, both past and present. It is not a secret that this relationship has been and is fraught with difficulties. Thus from all perspectives (M&M, society and environmental and social consultants) such a dissection, that highlights the realities, both good and bad, is uncomfortable. For this section of the colloquium to have any value, the honest but difficult approach needs to be taken.

Jan 1, 2000

By H. G. Denkhaus

Please allow me the temerity to reply to your reply to my contribution as follows: A fracture is brittle if plastic deformation is absent or, conversely a fracture is ductile if plastic deformation is present. Consequently, brittleness is specified by the degree of plastic deformation at fracture. This is the generally accepted definition. If other material properties (e.g. the quorient or the product of the uniaxial compressive and tensile strengths) under certain conditions are influenced by brittleness, or brittleness by them, these should not be called brittleness. If the one or the other author does that, he simply uses imprecise language. Even your remark, that ?Inyang and Pitt (1990) stated that the ratio of the compressive strength (sc/st) is directly proportional to brittleness?, confirms that the two quantities are not considered the same. For example:? The well known definition that a material is linear?elastic if the strain is directly proportional to the stress?does not mean that stress (measured in MPa) and strain (measured in %) are the same thing.

Jan 1, 2003

1. Book reviews Geophysical and geochemical techniques for exploration of hydrocarbons and minerals, edited by M. Sittig. (Reviewer: J. Keenan) Separation procedures in inorganic analysis. A practical handbook, by Roland S. Young. Charles Griffin, 1980. £23.00. (Reviewer: R. Murray-Smith) 2. Historical reprints Theinin~rs dictionary, by William Hooson. £14. Discovery of subterraneal treasure, by Gabriel Plattes. £12. Fodinae Regales (The Mines Royal), by Sir John Pettus. 3. De Beers' booklets Amborite - a remarkable new cutting material, by De Beers Industrial Diamond Division (P.O. Box 916, Johannesburg 2000). Booklet, 14 pp., free of charge. Natural and synthetic micron powders, by De Becrs Industrial Diamond Division (P.O. Box 916, Johannesburg 2000). Leaflet, 5 pp., free of charge. 4. New books Nickel in the environment, edited by J. O. Nriagu. New York, Wiley, 1980.928 pp. $65. Underwater minerals, by D. S. Cronan. London, Academic Press, 1980. 364 pp. $57.50. Data conversion integrated circuits, edited by D. Dooley. New York, Wiley, 1980.298 pp. $26.95 (cloth), $17.50 (paper). 5. NIM reports Report 2057 A mineralogical study of the Rooibokkop- Boschhoek copper deposit in the Marble Hall area. Report 2069 A utomatic setting of the distance between sample and detector in gamma-ray spectroscopy. Report 2070 The prereduction of chromites from the UG-2 Reef. Report 2075 The optimization of some of the conditions for analysis by spark-source mass spectrometry. Report 2082 A survey of the literature on gravity separation.

Jan 1, 1981

By S. K. Murphy, S. M. Spottiswoode, A. M. Milev, D. Geyser

A portable, stand-alone instrument especially designed for recording strong ground motion was used in this study to create a large database of peak particle velocities measured underground. A total number of 39 sites located in stopes mining Carbon Leader and Ventersdorp Contact Reefs were investigated. Peak particle velocities whith values up to 3 m/s were recorded at some sites. The data recorded on the skin of the excavations were compared to the data recorded by the mine seismic networks to determine the site response. The maximum site response was obtained for source radii of between 5 m and 30 m and events locating within 200 m of the site. The extreme values of peak particle velocities were obtained in cases were the face-area lay within the source radius. Un instrument portable unique spécifiquement conçu pour enregistrer les mouvements dynamiques des terrains, a été utilisé dans cette étude pour créer une base de données importante sur la vélocité maximum des particules, mesurée en souterrain. Un nombre total de 39 sites situés dans les excavations exploitant les récifs appelés ‘Carbon Leader et Ventersdorp Contact Reefs’, a été investigué. Une vélocité maximale avec des valeurs allant jusqu’ à 3 m/s a été enregistrée sur certains sites. Les données enregistrées sur le bord de l’excavation ont été comparées aux données enregistrées par les réseaux séismiques de la mine pour déterminer la réponse du site. La réponse maximum du site a été obtenue pour des sources de rayons entre 5 m et 30 m et des évènements situés dans les 200 m du site. Les valeurs extrêmes de vélocités maximales ont été obtenues pour les cas où la zone de face se trouve à l’intérieur du rayon de la source. Ein mobiles, alleinstehendes Instrument, speziell entworfen um starke Formationsbewegungen aufzuzeichnen, wurde in dieser Studie verwendet um eine große Datenbank von Partikelspitzengeschwindigkeiten, die Untertage gemessen wurden, aufzuzeichnen. Eine Gesamtanzahl von 39 Aufstellungsorten in den Schichtabbauorten vom Carbon Leader und Ventersdorp Contact Reef wurden untersucht. Partikelspitzengeschwindigkeiten mit Werten bis zu 3 m/s wurden an einigen Standorten aufgezeichnet Die an der Oberfläche des Grubenraumes aufgezeichneten Daten wurden mit jenen Daten verglichen, die vom seismischen Netzwerk der Grube notiert wurden, um die örtliche Reaktion des Standortes zu bestimmen. Die maximale Standortreaktion wurde für Ursprungsradien von zwischen 5 m und 30 m erhalten und Ereignissen die sich innerhalb von 200 m vom Standort befanden. Die extremen Werte der Partikelhöchstgeschwindigkeiten wurdenin jenen Fällen erreicht wo sich der Abbaubereich innerhalb des Ursprungsradiuses befand.

Jan 1, 2003