Name of the Project
Karowe underground project (UGP).

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 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 UGP 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.

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
Lucara announced in July 2023 that the cost of the project had increased by 25% to $683-million.

Planned Start/End Date
The project will be completed by the first half of 2028, instead of the previously anticipated date of the second half of 2026.

Latest Development
Lucara has reported in its results for year ended December 31, 2023, that the UGP remains a priority, with president and CEO William Lamb saying it represents an exciting and valuable future for the company.

Lucara invested $101.3-million in the UGP during 2023. By the end of the year, the production and ventilation shafts were both at 348 m below collar, or 666 m above sea level, and the process of establishing the first shaft stations and lateral connection between the two shafts (670 level) had started.

The miner will invest up to a further $100-million in the UGP this year.

Activities for the first quarter of this year include:

• the completion of mining and construction activities on the 670 Level station, including the connection of the two shafts and establishment of an electrical substation, sump and dewatering pumps, and ventilation doors;
• the procurement of underground equipment, including dewatering pumps, underground crush and conveyor systems, and the permanent stage winder;
• the commissioning of the permanent bulk air cooler system;
• the preparation of tender documents for the underground lateral development work; and
• a continuation of detailed design and engineering of the underground mine infrastructure and layout.

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.