Abstract

MUSENWA, L. et al. The new Cullinan AG milling circuit - a narrative of progress. J. S. Afr. Inst. Min. Metall. [online]. 2019, vol.119, n.2, pp.113-122. ISSN 2411-9717.  http://dx.doi.org/10.17159/2411-9717/2019/v119n2a3.

In 2017, Petra Diamonds completed the construction and commissioning of a modern, fit-for-purpose diamond processing plant at Cullinan Diamond Mine (CDM). The design of CDM's milling circuit is unconventional in that it comprises an autogenous (AG) mill with a grate discharge with large ports, low-revolution jaw crushers, and high-pressure grinding roll crushers with large operating gaps. In this paper we review the design to provide guidance on what is expected from the milling circuit and to demonstrate how the design aims to address challenges experienced in the old plant, which was based on staged crushing technology. We assessed the performance of the CDM AG milling circuit from commissioning and early production stages to examine its impact along multiple dimensions. In the assessment we sought to understand the lessons from our milling circuit regarding diamond liberation, energy consumption, and the future of diamond processing as a whole.

Keywords : kimberlite processing; autogenous milling; high-pressure grinding roll; diamond liberation; diamond damage.

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