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Sampling and Estimation of Diamond Content in Kimberlite Based on Microdiamonds Johannes Ferreira

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Sampling and Estimation of Diamond Content in Kimberlite Based on Microdiamonds Johannes Ferreira Sampling and estimation of diamond content in kimberlite based on microdiamonds Johannes Ferreira To cite this version: Johannes Ferreira. Sampling and estimation of diamond content in kimberlite based on micro- diamonds. Other. Ecole Nationale Supérieure des Mines de Paris, 2013. English. NNT : 2013ENMP0078. pastel-00982337 HAL Id: pastel-00982337 https://pastel.archives-ouvertes.fr/pastel-00982337 Submitted on 23 Apr 2014 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. N°: 2009 ENAM XXXX École doctorale n° 398: Géosciences et Ressources Naturelles Doctorat ParisTech T H È S E pour obtenir le grade de docteur délivré par l’École nationale supérieure des mines de Paris Spécialité “ Géostatistique ” présentée et soutenue publiquement par Johannes FERREIRA le 12 décembre 2013 Sampling and Estimation of Diamond Content in Kimberlite based on Microdiamonds Echantillonnage des gisements kimberlitiques à partir de microdiamants. Application à l’estimation des ressources récupérables Directeur de thèse : Christian LANTUÉJOUL Jury T M. Xavier EMERY, Professeur, Université du Chili, Santiago (Chili) Président Mme Christina DOHM, Professeur, Université du Witwatersrand, Johannesburg (Afrique du Sud) Rapporteur H M. Jean-Jacques ROYER, Ingénieur, HDR, E.N.S. Géologie de Nancy Rapporteur M. Wynand KLEINGELD, Consultant Willow View, Wells (Royaume Uni) Examinateur È M. Christian LANTUÉJOUL, Directeur de Recherche, MINES ParisTech, Fontainebleau Examinateur M. Matthew FIELD, Géologue principal, AMEC, Wells (Royaume Uni) Examinateur S M. Malcolm THURSTON, de Beers Group Services Ltd, Southdale (Afrique duSud) Invité E MINES ParisTech Centre de Géosciences 35 rue Saint-Honoré – 77305 Fontainebleau cedex Declaration I declare that this thesis is my own work, except where otherwise acknowledged or referenced in the text. It is being submitted for the Degree of Doctor of Philosophy at the Ecole des Mines des Paris. It has not been submitted before for any other degree or examination at any other university. __________ J.J. Ferreira August 2013 3 Dedicated to my family 5 Acknowledgements During the years with De Beers and Anglo American, I could not have had more opportunities to grow into and experience the science and art of mineral resource evaluation, than under the leadership of Dr. Wynand Kleingeld. I received invaluable exposure to size distributions and other aspects of diamonds under the management of Tinus Oosterveld. He shared with me all he knew about diamonds including the ‘secrets’ of microdiamonds. This thesis is an acknowledgement of the many years of his dedication in this field. I acknowledge: Christian Lantuéjoul for his support with the theoretical aspects of this methodology and helping me to finally write down this research; Chris Prins for his assistance with the documentation and for the computer system he assembled from SAS and Excel sources developed during our years at De Beers; Anglo American and the De Beers for opportunities created for me while employed; Niall Young, Malcolm Thurston and Matthew Field for support when this topic was still controversial; Special thanks to the friends at the Ecole des Mines in Fontainebleau. 7 Contents Declaration .............................................................................................................................................. 3 Acknowledgements ................................................................................................................................ 7 Contents .................................................................................................................................................. 9 Préambule ............................................................................................................................................. 13 Preamble ............................................................................................................................................... 15 Glossary ................................................................................................................................................. 17 Introduction française .......................................................................................................................... 21 1 Introduction .................................................................................................................................. 27 1.1 Background ........................................................................................................................... 27 1.2 This research ......................................................................................................................... 29 1.3 Diamond Size ........................................................................................................................ 31 1.4 Diamond concentration ........................................................................................................ 32 1.5 Diamond Content .................................................................................................................. 33 1.6 Sampling................................................................................................................................ 34 1.7 Application ............................................................................................................................ 35 1.8 Further research ................................................................................................................... 35 PART I METHODOLOGY ....................................................................................................................... 37 2 Diamonds in Kimberlite ................................................................................................................ 39 2.1 Kimberlite Deposits ............................................................................................................... 41 2.2 Diamonds in Situ ................................................................................................................... 43 2.3 Microdiamonds ..................................................................................................................... 44 2.3.1 Definition ...................................................................................................................... 44 2.3.2 The Beginning ............................................................................................................... 45 9 2.3.3 Application ..................................................................................................................... 46 2.3.4 Benefits .......................................................................................................................... 47 2.4 Sample stones and sample carats ......................................................................................... 48 2.5 Diamond size (frequency and log probability) ...................................................................... 49 2.6 Diamond liberation (maximum lockup) ................................................................................. 55 2.7 Diamond Value ...................................................................................................................... 58 2.8 Kimberlite Evaluation ............................................................................................................ 59 2.8.1 Evaluation Purpose ........................................................................................................ 60 2.8.2 Evaluation Sequence ..................................................................................................... 60 2.9 Kimberlite sampling ............................................................................................................... 61 2.9.1 Sampling phases ............................................................................................................ 62 2.9.2 Microdiamond sampling ................................................................................................ 63 2.9.3 Sampling Methods ......................................................................................................... 71 3 Modelling kimberlite diamond content ........................................................................................ 73 3.1 Diamond occurrence ............................................................................................................. 75 3.1.1 Spatial aspects ............................................................................................................... 75 3.1.2 Poisson Process ............................................................................................................. 75 3.1.3 Cox Process .................................................................................................................... 76 3.1.4 Towards diamond content ............................................................................................ 78 3.2 Graphic modelling of diamond
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