Trade-off studies and additional technical assessments

The results of the metallurgical tests are used to continue process trade-off studies:

• Simulation of pre-concentration flowsheets including bulk rock sorting in the crushing circuit. Further work is required to optimise the ore sorting and CGR pre-concentration steps ahead of conventional copper flotation.
• Coarse particle flotation tests confirmed that a CGR step in the primary milling circuit should enable about 15-20% of mill feed to be rejected as a coarse tailings stream without reducing overall copper recovery. This step was incorporated in the base case flowsheet for the PEA Technical Report, resulting in a low-cost increase in processing capacity.
• Concentrator and hydrometallurgical plant capacity determination based on revenue versus cost trade-offs. A 28 Mtpa concentrator plant and 7 Mtpa hydrometallurgical plant were selected for the PEA Technical Report.
• Technical comparisons of alternative pre-concentration and leach processes to recover copper from low grade chalcopyrite mineralisation containing less than about 0.225% Cu. For the lower-grade parts of the ore body, only a few processing methods have shown they can recover copper effectively and remain commercially viable. These include sorting the ore before processing, followed by heap leaching using bacteria, or heap leaching supported by chloride or nitrate.

Several additional trade-off studies will be included in later phases of project development, including:

• Cost and transportability comparison of flotation concentrate and copper cathode by road or rail to Walvis Bay as an alternative to transporting all product by road to Lüderitz.
• Consideration of different materials handling equipment to transport low-grade mineralisation to the heap leach pad. A rail-run conveyor will be considered as well as the base case of a belt conveyor following tertiary crushing.
• Generation of electrical power using renewable and battery storage technology, supplemented by diesel generation, versus sourcing of power solely from the national and regional grid in Namibia. For the technical report, 37% of power sourced from a planned Photo Voltaic (PV) Plant was included in the cost estimates.
• Consideration of alternative water supply sources with conceptual design and costing studies.

These studies were used for the preliminary design and cost estimates for the concentrator process flowsheet outlined in the 2025 PEA technical report, as well as infrastructure designs and cost estimates by Knight Piésold and other consultants. Additionally, a separate hydrometallurgical plant design and cost estimate was developed, building on earlier work from 2020 and 2021 and supplemented with data from DRA’s cost database.