TOMRA delivers potentials for diamond recoveries at Karowe mine

Lucara Diamond CorporationTOMRA’s technology has unlocked the huge potential of the Karowe diamond mine in Botswana

Lucara Diamond Corporation owns the Karowe diamond mine in Botswana, which has been in production since 2012. The mine is recognised as one the foremost producers of very large, high-quality Type IIA diamonds in excess of 10.8 carats. Historic recoveries include the 1,109-carat Lesedi La Rona – the second-largest gem-quality diamond ever found – and the 813-carat Constellation diamond. Lucara’s success at the Karowe mine continues, most recently with rare gem-quality blue and pink diamonds recovered in September 2019.

Eira Thomas, CEO of Lucara, said, “When production started, it became apparent that the diamond population was quite coarse, and that necessitated a re-think on how we could adjust or optimise flow sheet focused on diamond value preservation.”

“That was our real focus and goal in starting the conversation with TOMRA, about how can we do this better, how can we actually get diamonds out of our mineralised ore in a more efficient way and in a way that actually maximises the value of those diamonds and minimises the damage of those goods,” Thomas noted.

The AK6 Kimberlite found in the Karowe presents a difficult challenge, as John Armstrong, vice-president, technical services for Lucara Diamond Corporation, explained, “It has a very high DMS yield, in that up to 10 to 15 per cent of the material that would go into the plant would report as a heavy-metal concentrate, making it a very difficult ore body to process in a traditional diamond processing scenario.”

Armstrong further added, “We undertook a series of testing campaigns and investigations to explore alternative technologies. We elected to go with TOMRA as our partner in moving forward in getting this technology to the mine into part of the circuit that hadn’t been envisioned previously.”

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