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, which 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 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
In the year to December 31, 2021, several activities were undertaken, including:

• the presinking of the ventilation and production shafts to -36 m and 41 m respectively below the shaft collar, with shaft liner toe-in construction completed in the ventilation shaft, and shaft lining continuing back to the subcollar. Toe-in construction also started in the production shaft by year end.
• the clearing for and construction of 40 out of 88 tower foundations for the
• 29 km, 132 kV transmission line bulk power upgrade.
• the mobilisation of headframe materials and surface infrastructure, including a 200-person camp and a water treatment facility.
• the commissioning of the temporary generator farm, which will be used to power the shaft hoists during sinking until line power is commissioned, was completed.

Activities for the Karowe underground project in 2022 include:

• the commissioning of the four main sinking winders.
• the completion of the steel headframe structure for the production and ventilation shafts.
• the transition and sustained main sinking for the production and ventilation shafts. 
• the continuation of detailed design and engineering of the underground mine infrastructure and layout.
• The commissioning of the 29 km, 132 kV bulk power supply powerline by December 2022.

Key Contracts, Suppliers and Consultants
UMS Botswana (presink construction contract); UMS South Africa (shaft sinking equipment procurement); METS International, a subsidiary of UMS (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.