Underground development at diamond producer Lucara Diamond’s Botswana-based Karowe mine is expected to extend its operational life beyond 2040, with significant progress achieved in 2024, particularly in shaft sinking and lateral development, connecting the production and ventilation shafts.

A total of 702 m was sunk in 2024, comprising 375 m in the production shaft and 327 m in the ventilation shaft.

In addition, a total of 464 m of lateral development was completed last year, successfully connecting the two shafts at the 670-level and 470-level station development, with each level equivalent to a metre above sea level.

By the end of the fourth quarter of 2024, the production shaft had reached a depth of 731 m out of a planned final depth of 770 m; while the ventilation shaft had reached 671 m, approaching its planned final depth of 722 m.

The Karowe Underground Project (UGP), which saw expenditure of $64.7-million in 2024, is designed to access the highest value portion of the Karowe orebody, with initial underground carat production predominantly from the eastern magmatic/pyroclastic kimberlite south unit.

The project is expected to increase Karowe’s mine life to beyond 2040.

“[Lucara’s] strategic focus on the underground mining project showed significant advancement, with shaft depths reaching new records,” says Lucara president and CEO William Lamb.

Notably, the critical path ventilation shaft is ahead of Lucara’s July 2023 rebase schedule.

Key infrastructure developments were also completed in 2024, including the construction and pre-commissioning of the permanent bulk air coolers at the production shaft, which were completed in July 2024.

Fabrication and construction of the permanent personnel and materials winder continued in 2024, representing the last major component of the permanent winders.

Further, in 2024, the adjudication and review of underground lateral development tender documents started, while advanced mining engineering efforts focused on supporting shaft sinking, underground infrastructure and finalising drilling level plans.

In addition, orders for shaft steelwork were placed in October 2024.

Planned Activities for 2025
Looking ahead to this year, capital costs for the Karowe UGP are projected to reach up to $115-million, and will focus primarily on shaft sinking activities to their final depths, equipping the production shaft and station development.

The tendering of the underground lateral development contract and underground equipment purchases are set to be completed this year.

The ventilation shaft is expected to sink to the 355-level, at which point station mining excavation will start, including the top of fine ore bins, before continuing sinking activities to the 310-level.

The production shaft will target a depth to the 285-level, with the completion of the 285-level skip loading station.

Construction will continue on the winder building structure and the winder driver’s cabin, while work on evaporation pond earthworks, civils and an updated water model are also planned.

Procurement of underground equipment will proceed this year, including for an additional load, haul and dump vehicle for production shaft station 285-level development.

Further, major components of the underground crusher and dewatering pumps are expected to be delivered to the site.

While openpit mining is expected to continue until the end of this year, providing mill feed throughout this period, production from the underground operation is anticipated to start in the first half of 2028.

Stocked with material from openpit mining from the North, Centre and South Lobes – sourced from both working and life-of-mine stockpiles – will ensure uninterrupted mill feed until 2027 while underground development continues.

The revised total project cost at completion is forecasted at $683.4-million, including contingency.

Following this, ore from the underground project is scheduled to start offsetting stockpiled material with high-grade ore from the underground development.

“Steady progress in shaft sinking marks significant advancement in our underground project. This strategic investment will extend Karowe’s productive life, ensuring we continue to unearth extraordinary diamonds from this exceptional deposit for years to come,” Lamb concludes.