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
Lucara has updated the estimated capital cost, reporting an increase from $534-million to $547-million to reflect expected pricing changes following the execution of the main sink contract. The underground expansion is expected to extend Karowe’s mine life by 13 years.

Planned Start/End Date
The company will complete shaft sinking in 2024 and the ramp-up is scheduled for the first quarter of 2026, with full production from the underground mine expected in the second half of that year.

Latest Developments
Work on the Karowe underground project has made significant strides in the past year, achieving several important milestones.

All presinking activities have been completed on schedule and budget, a main shaft sinking contract has been executed and main shaft sinking activities are continuing to ramp up.

However, equipment and operational challenges are negatively impacting on planned cycle times. Cycle time is the period it takes to complete a series of activities within the sinking process to achieve the next planned vertical advance.

Lucara states that it has made equipment and personnel changes, as well as shift and rotation schedule optimisations along with the roll-out of a behavioural-based safety training programme to resolve these issues.

“The impact of delays and a slower-than-anticipated ramp-up in shaft sinking cycle times, together with experience gained from our first grouting programme will be incorporated into a refreshed schedule and budget which is expected to be completed in the second quarter of 2023,” president and CEO Eira Thomas has said.

Lucara completed the first phase of grouting in the production shaft between December and February, confirming the planned approach and methodology to keep water inflows from the stand stones at bay.

During 2022, Lucara invested $106-million in the Karowe project, with a total investment to date of $226.1-million. The company is working on a capital cost estimate of $547-million for the project.

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.