Principles of using microdiamonds for resource estimation: 1—The impact of mantle and kimberlite processes

CIM Journal , Vol. 7, No. 4, 2016

J. Stiefenhofer and M. L. Thurston
Technical and Sustainability, De Beers Group Services (Pty) Limited, Southdale, South Africa

D. M. Rose
School of Statistics and Actuarial Science, University of the Witwatersrand, Johannesburg, South Africa

I. L. Chinn
De Beers Exploration, De Beers Group Services (Pty) Limited, Southdale, South Africa

J. J. Ferreira
Johan Ferreira & Associates Ltd, Wokingham, Berkshire, United Kingdom

http://dx.doi.org/10.15834/cimj.2016.26
Abstract Concerns about using microdiamonds for resource estimation have been raised by workers because multiple diamond populations exist in many parts of the mantle source region, small diamonds in kimberlite could be exposed to proportionately greater levels of resorption and modification, and euhedral microdiamonds could crystallize immediately prior to kimberlite eruption. This paper addresses these concerns; discusses the geology of the mantle, the principal diamond host rocks, and the impact of mantle processes; compares micro- and macrodiamond properties and features; and outlines steps to identify and mitigate the risk of diamond resorption and its impact on the diamond grade-size relationship.
Keywords: Burr, Diamond, Distribution, Eclogite, Kimberlite, LogLaplace, Lognormal, Mantle, Morphology, Paragenesis, Pearson V, Peridotite, Populations, Resorption, Resource evaluation
Résumé Des travailleurs se sont interrogés sur l’utilisation de microdiamants pour estimer la ressource; en effet, de multiples populations de diamants existent dans plusieurs secteurs de la région source dans le manteau. Des petits diamants dans la kimberlite pourraient être exposés à des niveaux proportionnellement supérieurs de résorption et de modification; de plus, des diamants idiomorphes pourraient cristalliser immédiatement avant l’éruption de la kimberlite. Le présent article traite de ces questions, discute de la géologie du manteau, des principales roches-mères des diamants et de l’impact des processus dans le manteau, compare les propriétés et les caractéristiques des micro- et des macrodiamants et définit les étapes pour identifier et mitiger le risque de résorption des diamants et son impact sur la relation entre la taille et la qualité des diamants.
Mots-Clé Barbure, diamant, distribution, distribution de Pearson de type V, éclogite, évaluation des ressources, kimberlite, log-Laplace, log-normal, manteau, morphologie, paragenèse, péridotite, populations, résorption
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Publication: CIM Journal
Issue: 4
Volume: 7
Year: 2016
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Summary: The otherwise waste heat in many water streams in the mining industry can be used to provide space heating of adjacent infrastructure including laboratories, workshops, and offices. This can be achieved by using heat pump systems, which can work as a replacement or in conjunction with existing space heating. In the example investigated—process cooling streams at an ore smelter—the analysis provided illustrates that annual heating costs can be 19% lower and a simultaneous 62% reduction in CO2...
Publication: CIM Journal
Author(s): I. M. Ross, G. M. Ross, J. A. Scott
Keywords: Heat pump, Heat recovery, Mineral processing, Pyrometallurgy, Smelting, Space heating, Waste heat
Issue: 4
Volume: 7
Year: 2016
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Summary: This paper presents regional radiometric gamma-ray spectrometry maps of Syria for total radioactivity (Ur) and surficial concentrations of equivalent uranium (eU). The maps were created by merging airborne and ground-based gamma-ray spectrometric survey datasets. On the regional radiometric eU map, eU anomalies are closely related to either phosphate and/or glauconite deposits. The Ur and eU maps delineate the boundaries of three phosphate deposits, close to the Palmyrides ridge, in the...
Publication: CIM Journal
Author(s): J. Asfahani, M. Aissa, and R. Al-Hent
Keywords: Airborne gamma-ray spectrometric survey, Equivalent uranium (eU), Ground-based gammaray spectrometric survey, Total radioactivity (Ur)
Issue: 4
Volume: 7
Year: 2016
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Summary: Copper electrodeposition from synthetic and authentic acid mine drainage (AMD) is inhibited by ferric iron (Fe(III)), through re-oxidation of copper. Polarization to –2.5 V versus standard hydrogen electrode prevents the dissolution of predeposited copper from the cathode. Above pH 1, copper deposition is independent of Fe(III) concentration to approximately 25 g/L. Fe(III) is reduced to ferrous iron (Fe(II)), with a high combined current efficiency for iron and copper reduction. In a divided...
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Author(s): B. Vollick, A. F. Souza, C. Shamshoom, P. Maharaj, D. Bejan, and N. J. Bunce
Keywords: Cathodic deposition, Oxidation of copper by ferric iron, Remediation of acid mine drainage
Issue: 4
Volume: 7
Year: 2016
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Summary: Resin-anchored rebar is commonly used for rock support in mining. The rock properties and environment determine the average bond strength, allowing mine engineers to select the appropriate length and installation pattern for the support. In weak material such as potash, the average bond strength tends to be lower than for a typical hard-rock installation. Determining the failure mechanism by which the support fails in soft-rock applications could lead to improved bond strength and better...
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Author(s): D. Neely, D. Milne and L. R. Feldman, C. Smith
Keywords: Bond strength, Potash, Reinforcing bar (rebar), Support capacity
Issue: 4
Volume: 7
Year: 2016
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Publication: CIM Journal
Author(s): B. Galy and L. Giraud
Keywords: Hoist safety, Independent protective layer (IPL), Layer of protection analysis (LOPA), Life cycle, Probability of failure on demand (PFD), Regulation, Risk, Risk mitigation strategy, Safety instrumented system (SIS), Safety-integrated level (SIL), Safety related control function (SRCF), Software safety
Issue: 4
Volume: 7
Year: 2016
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