Name of the Project
Karowe underground project.
Location
Botswana.
Project Owner/s
Lucara Diamond Corp.
Project Description
The Karowe mine is an existing conventional drill-and-blast openpit operation, with diesel excavators and trucks providing an average of 2.6-million tonnes a year of kimberlite feed for the mill. The openpit mine operation is expected to terminate in mid-2026, ending at an elevation of about 700 m above sea level.
The project is expected to extend the mine life to at least 2040, with underground carat production coming predominately from the highest-value EM/PK(S) unit.
Longhole shrinkage underground bulk mining has been selected to provide early access to higher-value ore and allow for a short payback period.
The underground project is designed to access the South Lobe kimberlite resource below the current planned bottom of the openpit, which is expected to be at about 700 m above sea level, to a depth of 310 m above sea level.
Access to the South Lobe underground will be through two vertical shafts.
A 767-m-deep production shaft, 8.5 m in diameter, driven from surface, will be equipped with two 21 t skips for production hoisting and a service cage for man-and-material movement through the mine. This shaft will also serve as the main fresh-air intake to the mine.
A second shaft, 6 m in diameter, driven 733 m deep from surface, will form the main ventilation exhaust pathway.
All underground mined kimberlite will be processed at the existing Karowe processing plant over a 13- to 15-year period following the cessation of the current openpit operations, which is expected to occur in 2026.
Life-of-mine production (remaining openpit and underground) is estimated at 7.4-million carats.
The underground expansion is expected to extend Karowe’s mine life by 13 years.
Potential Job Creation
Not stated.
Net Present Value/Internal Rate of Return
The project has an after-tax net present value, at a 5% discount rate, of $750-million, with a payback of about three years, for the combined openpit and underground mine.
Capital Expenditure
$534-million. In the year ended December 31, 2021, $86.3-million was spent primarily on the engineering and procurement of long-lead items and the start of construction activities.
Planned Start/End Date
The Karowe underground expansion project was formally approved in September 2021. Mine ramp-up is expected in the first quarter of 2026, with full production from the project expected in the second half of 2026.
Latest Developments
Shaft presinking at the Karowe mine was completed at the end of February.
“Each shaft is about 52 m below collar. The final depth for the ventilation shaft is 730 m below surface, and 767 m below surface for the production shaft,” Lucara VP technical services Dr John Armstrong has said.
Shaft sinking for Karowe is scheduled for completion in 2024 and the ramp-up to production from the underground operation is scheduled for the second half of 2026.
The EM/PK(S) geological unit of the South Lobe is the source of the biggest diamond recoveries from the Karowe mine and is expected to provide more than 90% of the mill feed during the first three years of underground production. The EM/PK(S) unit currently provides about 35% of the mill feed from the openpit’s production.
Meanwhile, Lucara’s shaft sinking projects at the Karowe mine have been delayed, owing to the Covid-19 pandemic.
During the lockdown period, Lucara secured project financing and focused on detailed engineering and design works, as well as the procurement of long-lead time items required for shaft sinking activities, Armstrong has noted.
“The project had a one-year delay from the original feasibility schedule. However, during the presink, and as the project is transitioning to the main sink, no significant challenges have been encountered thus far.”
Long-term shaft maintenance requirements at the Karowe mine are still in the planning phase.
Key Contracts, Suppliers and Consultants
UMS Botswana (presink construction contract); UMS South Africa (shaft sinking equipment procurement); UMS subsidiary METS International (shaft engineering contract); and JDS Energy & Mining (engineering, procurement and construction management) for the execution of the Karowe underground project.
Contact Details for Project Information
Lucara Diamond Corp investor and public relations, tel +1 604 674 0272 or email info@lucaradiamond.com.