Addressing the elephant in the room: Integrating diamond breakage into kimberlite geometallurgy
DOI:
https://doi.org/10.17159/Keywords:
diamond breakage, geometallurgy, impact energy, kimberlite processing, natural diamond properties, simulant testingAbstract
Global natural diamond production is in decline, with several major mines nearing depletion and few new Tier 1 kimberlite deposits being identified. As supply tightens, every recovered carat becomes more economically significant, particularly larger high‑value stones. In this context, reducing diamond breakage during processing has become essential for sustaining value in modern kimberlite operations. Diamond breakage remains a significant source of value loss in kimberlite processing, yet most kimberlite geometallurgical approaches still overlook diamond‑specific characteristics. Natural diamonds possess a suite of intrinsic properties that strongly influence their mechanical response to applied stress, including size distribution, morphology, crystallographic orientation, cleavage, inclusions, and internal strain, to name a few. These characteristics govern how the stress is distributed through the crystal and how fractures initiate and propagate. Despite their importance, many traits are difficult to quantify at scale, and destructive testing restricts direct measurement, leaving a critical knowledge gap at the heart of value recovery. For geometallurgical modelling, the central challenge is identifying which diamond traits truly control breakage under operational conditions and developing practical, scalable proxies for them. Research at the University of Cape Town addresses this by combining controlled impact testing of synthetic diamond simulants in kimberlite analogues with detailed characterisation of natural diamonds. Simulant based tests yield breakage probabilities, energy thresholds, and fragmentation patterns through models such as the T10 model, Fmat, and progeny distributions, defining a ‘safe operating window’ where kimberlite breaks efficiently while diamonds remain intact. Complementary investigations of natural stones reveal readily identifiable features, such as morphology, cleavage expression, and inclusion distribution, that most strongly correlate with breakage behaviour. Integrating these proxies into a geometallurgical framework will allow more accurate prediction of diamond breakage across ore domains, leading to improved comminution strategies, reduced value loss, and more reliable recovery forecasting for kimberlite processing plants.
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Copyright (c) 2026 Sara Burness, Sherry Bremner, Megan Becker, Geoffrey Howarth, Aubrey Mainza
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