Elsevier

Results in Engineering

Volume 7, September 2020, 100154
Results in Engineering

Size reduction of CCZ polymetallic nodules under repeated impact fragmentation

https://doi.org/10.1016/j.rineng.2020.100154Get rights and content
Under a Creative Commons license
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Highlights

  • CCZ polymetallic nodule tensile strength measurements.

  • Nodule tensile strength is a strong function of nodule size.

  • Impact fragmentation experiments on polymetallic nodules.

  • Impact fragmentation modelling with sparse breakage matrix.

  • Lower limit in nodule size for susceptibility to impact fragmentation under hydraulic transport conditions.

Abstract

Polymetallic nodules provide an alternative source of valuable metals. Nodules from the seabed of the Clarion Clipperton Zone (CCZ), a prospective mining area, are typically abundant at depths of around 5 ​km. Mining these nodules comprises excavation or pick-up of nodules and hydraulic transport of nodules from the seafloor to the surface. The particle size distribution of the nodules, an important design parameter, will change during transport under influence of different processes. One of these processes is impact fragmentation, especially occurring in centrifugal pumps. Recent research has led to improved understanding of impact fragmentation of polymetallic nodules, but quantification of the degradation process still is an open question due to scarcity of breakage data. In this paper we present a detailed analysis of nodule strengths and stresses occurring during impact and we propose an impact fragmentation model based on limited breakage data. The model is compared with the experiments and we comment on application of this model in engineering practice.

Keywords

Particle breakage
Impact fragmentation
Polymetallic nodules
Deep ocean mining

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