Canada headquartered diamond mining company Lucara Diamond Corp. on 4 September held a ceremony to commemorate the momentous occasion of a production shaft last blast celebration at its Karowe diamond mine in Botswana. The occasion celebrated both the last blast as well as the achievement of 2000 lost time injury (LTI) free days.

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“What a milestone we are celebrating today. A critical phase in the development of this mine is now complete, delivered ahead of contractual schedule and, most impressively, without a single lost time injury.

“That is an extraordinary achievement. Congratulations to each and every one of you,” said Digby Glover, CEO of United Mining Services (UMS) Group, in his speech.

UMS provides engineering design, shaft sinking and construction services to Karowe. The company is responsible for completing the shaft sinking process at the mine.

Making history

William Lamb, president and CEO of Lucara, said this significant development ensures that Karowe is well positioned to continue reaching milestones and making history.

“Karowe is one of the world’s foremost producers of large, high quality, Type IIA diamonds in excess of 10.8 carats, including the historic 1,758 carat Sewelô, the 1,109 carat Lesedi La Rona and the 813 carat Constellation which sold for a record US$63.1 million.

Most recently, the 2,488 carat Motswedi was also recovered, one of the largest rough diamonds ever unearthed. This achievement of the last blast puts us in a position to continue this legacy.”

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The mine, which started commercial operations in 2012 as an open pit mine, has mined and processed approximately 30 Mt of ore, with the open pit reserve expected to be fully depleted early next year.

Lucara had evaluated extending the mine life through mining underground, with processing of stockpiles taking place opportunistically through the mine life.

Access to the underground mine will be from a 770m deep production shaft, 8.5 m in diameter, driven from surface to 245 amsl.

The shaft will be equipped with two 21 t skips for production hoisting and a service cage for personnel and material movement through the mine. It will also serve as the main fresh air intake to the mine.

The second shaft is 6.0 m in diameter, 722 m deep, and driven from surface to 267 amsl. It serves as the main exhaust route and secondary egress for the mine.

The two shafts are offset from the kimberlite pipe approximately 375 m northwest of the south lobe, well outside of the potential subsidence zone, and 100 m from each other.

“The significance of reaching the shaft bottom is the completion of all the blasting activities in the shaft. It’s a critical milestone for us because it starts the next phase of any shaft work that needs to be done, the shaft equipping.

“This is critical for Lucara Botswana to complete and commission the shaft and put it into production,” said Simon Wolmarans, senior project manager at Lucara.

He added that achieving the shaft bottom allows  the project to commence the shaft equipping phase, which will allow the mine to hoist more tonnages through the material handling system during the lateral development phase.

“This event today is a traditional celebration. The shaft sinking process is one of the riskiest activities you can carry out in mining. And the fact that it has been competed without causing any serious injuries is cause for celebration,” added Glover.

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He said the teams were able to achieve 2000 LTI free days because they worked together. “There has been a massive effort from all stakeholders and teams to make sure work was done safely.

“This includes the authorities in terms of legislation, the mine itself in terms of its supervision and oversight including the engineering team that was involved in setting up and designing what’s been done here, as well as the onsite team that physically excavated the ground out of the earth.”

Success through collective effort

UMS’s involvement with the Karowe project started in 2019, during the final stages of the feasibility study. Its initial role was to review the shaft component, prepare designs for early works and initiate long-lead procurement.

Since then, the journey has been transformative, says Glover. “This success is the result of a collective effort. It is only fitting that we take this moment to acknowledge all those who contributed.

“Developing an underground mine is no small feat. It demands time, significant investment and the ability to navigate risks both known and unforeseen. It requires the dedication, expertise and resilience of a diverse team working toward a shared goal.

“I remember the early days, the excitement and commitment of the small project team working on initial designs. That energy set the tone for everything that followed.

“I recall the tough engineering and contractual negotiations that laid the foundation for success. Those hard conversations made the road ahead a little smoother.”

“I can recall the sinking team, gathered from across the globe, sharing stories and their passion for the craft as they stood at the edge of the new boxcut. The presink was completed ahead of schedule, a rare and remarkable achievement.”

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Nigel Townshend, UMS nonexecutive chairperson, added that the shaft is important to the future of the Karowe mine as it holds significance for many stakeholders.

“The mine has created employment for people across Botswana. It has also fostered high-performing teams with rare and valuable shaft sinking skills.

“These skills can serve ongoing operations or can contribute to the broader growth of Botswana’s mining economy by being deployed on future underground projects.”

Glover said the equipping of the shaft was already underway, with the steelwork already being delivered to site. “This phase will require the same level of focus, collaboration and excellence. I am looking forward to the continued success we will achieve as a team.”