Tomra sorter boosts Lucara’s exceptional finds

Lucara Diamonds – Karowe Mine

Lucara Diamond Corp. owns the Karowe diamond mine in Botswana, 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.

Initial work on the mine was carried out by previous owners in the 1970s with the technology available at the time, which had its limitations.

“What we realized in looking at the diamonds that resulted from that work is that many of them were actually broken,” says Eira Thomas, CEO of Lucara. “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 optimize flow sheet focused on diamond value preservation. That was our real focus and goal in starting the conversation with Tomra.”

The AK6 kimberlite found in the Karowe presents a difficult challenge, as John Armstrong, VP technical services for Lucara explains. “It has a very high DMS yield, in that up to 10% to 15% of the material that would go into the plant would report as a heavy metal concentrate, making it a very difficult orebody to process in a traditional diamond processing scenario. We undertook a series of testing campaigns and investigations to explore alternative technologies. We elected to go with Tomra.”

Tomra’s solution delivered very quickly, exceeding all expectations, said Thomas. “When we put in the large diamond recovery circuit in 2015, it was within two weeks of making this investment, which was somewhere around $30 million to $35 million, that we recovered those two exceptionally large diamonds, so in this case it was under two weeks we’d already had two times our return on that investment.”

The Lucara project clearly shows that Tomra stands out not only for its industry leading technology but, very importantly, for its extensive knowhow and approach to working with customers, which it views as a true business partnership.

Thomas explained the reasons for their choice of working with Tomra. “We felt, certainly, that the technology that Tomra offered was the best. But, more importantly, I think it was really around the approach, the attitude of collaboration and willingness to actually work with Lucara … We just felt that by working with a team of experts that understood the problem and had technology that could help us, we could together come up with a solution that made sense.”

Armstrong agrees. “As part of the process that made working with Tomra unique and special was their willingness to view the relationship between Lucara and Tomra as a partnership, and we were both investing in this, and we were both going to learn a lot from it, and we relied on each other to ensure that we were going to be successful.”

As the world market leader in sensor-based ore sorting, Tomra is responsible for developing and engineering cutting edge technology made to withstand harsh mining environments. Tomra maintains its rigorous focus on quality and future-oriented thinking with technology tailor-made for mining.

(This article first appeared in the Canadian Mining Journal)

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