Deep Yellow Limited has submitted the full 2025 Definitive Feasibility Study (DFS) for the Tumas Project to the Independent Technical Expert appointed by Nedbank, the Mandated Lead Arranger for project financing. The company is seeking approximately US$350 million (about N$6.7 billion in debt financing to fund construction of its flagship uranium mine. The submission includes all works and results carried out up to the end of March 2025 and is considered sufficient to complete due diligence.
The Final Investment Decision (FID), initially scheduled for earlier in 2025, was postponed by the company in April due to uranium prices at the time. Despite the delay, development activities have continued.
Detailed engineering, led by Ausenco Services, is progressing well with 3D model progress for the plant reaching total weighted progress of 44%. Model development is advancing at about 1.5% per week and will accelerate as more certified vendor data and resources are committed.
The process flowsheet was frozen in March 2025, and the key project definition documents being the Process Flow Diagrams (PFD), Mass and Energy Balance (MEB), Process Design Criteria (PDC), Mechanical Equipment List (MEL), General Arrangement (GA) and plant layout, are all now at an “issued for design” status. Detailed engineering is now underway on an informed environment, with little rework likely to be required.
Eight “awarded” packages comprise the early works for the Project such as construction access road, site offices and Engineering, Procurement and Construction Management (EPCM) services. Four packages “approved for award” are awaiting FID prior to placement of final orders.
Eleven packages where a “preferred vendor has been selected and vendor data ordered” include many of the long lead time major mechanical items such as mills, thickeners, crushers and large agitators. Nine packages “under evaluation” have been competitively bid and the tenders are being evaluated. Eleven packages “approved for tender” include the major fabrication packages, electrical and instrumentation installation and structural, mechanical, piping and platework (SMPP).
The early works program aimed at preparing the site for commencement of major works has largely been completed. The construction access road is now complete and ready for the commencement of major activities at the site.
The new borefield that will supply dust suppression and some process water has also recently been completed. The bores will be equipped and delivery pipelines installed in the current half-year in readiness for the commencement of major site works and particularly the bulk earthworks at the process plant site, which is also planned to be completed in the current half-year. The initial site construction offices and communications (phone and radio) systems are now complete.
The final mine scheduling, incorporating the data obtained in the recently reported grade control drilling campaign and associated tailings storage facility (TSF) scheduling is now underway, with inhouse specialists and consultants that have been used during the study phases of the Tumas Project. This work and the re-costing of reagents and consumables as part of the operational readiness program will be used to further optimise the Project outcomes in preparation for FID.
The major utilities for the Project, being power and water supply, are both subject to draft offers of supply by the relevant Namibian state authorities: NamPower and NamWater respectively. The power supply for Tumas will also incorporate a Build, Own, Operate and Transfer (BOOT) solar array that will be contracted to provide at least 30% of the Project’s power needs and materially reduce the average power cost and carbon dioxide footprint for Tumas.
The NamPower and NamWater supply contracts are well-advanced and expected to be settled within the current quarter. Contracts for the supply of the associated infrastructure, which will be supplied by the Project and then transferred to either NamWater or NamPower to operate and maintain (consistent with Namibian legal requirements), are also well-advanced with suitably experienced, locally-based engineering contracting companies.
The operational readiness plan (ORP) is being taken from the conceptual plan incorporated and costed into the DFS to a detailed ORP that will prepare the Company, in terms of policies and procedures, as well as human resources for the commissioning and operations phases of Tumas.
The key areas being addressed include administration, financial control, human resources and procurement, as well as safety, health, environment and radiation (SHER) teams. Some of these people have already been identified and engaged. The mining owner’s team establishment for the pre-production mining phase includes mining engineering, mine planning, survey, geology and grade control.
The onboarding of the process operations and maintenance teams will also be scheduled and key people engaged as need increases and numbers ramp-up. These teams will play a crucial role in all phases of commissioning and the operational ramp-up to full production.
These teams will also develop the detailed operating procedures and standards necessary for the Project to successfully commission and ramp-up to full production. The establishment of logistics and supply plans for the operational, as apart from the Project execution, needs of Tumas and preparation of supply contracts for all its operating needs is ongoing. This builds on the already established working relationship with local and national authorities in Namibia.
The pre-mining, 12.5 m x 12.5 m spaced detailed grade control drilling program commenced in mid-August 2024 and was completed in late April 2025. A total of 3,127 Reverse Circulation (RC) holes were drilled for 42,848 metres, with 325 holes for 3,510 metres completed in the June 2025 quarter.
All drill holes were logged with downhole gamma tools for uranium grade estimations along with geological logging. Preliminary indications are that the drilling has confirmed the tenor of the current Mineral Resource Estimate within the area of the planned initial open pits. The current Ore Reserves Estimate (ORE) for this portion of the orebody selected for initiation of first mining is being refined and this assessment is currently underway.
Drilling and pump testing of four additional water production holes were recently completed. A groundwater monitoring drilling program and sampling campaign was carried out at the eastern end of Tumas 3 to isolate an environmentally sensitive area, located south of the plant site.
Thirty-three deeper monitoring bores were drilled to understand the elevation of the groundwater table. Fourteen shallower monitoring bores were drilled adjacent to selected deeper monitoring bores to determine potential head and chemistry variations.
Approximately 36 short-term pumping tests were completed to evaluate hydrogeological parameters of the aquifer. Five trenches were excavated in the area for soil sampling and to isolate the root distribution of the Salsola plant species that exists within the sensitive area.
Twenty-one soil samples were submitted for soil moisture, particle size analysis and standard chemistry analysis. Forty groundwater samples were submitted for general chemistry and metals analysis. In early July 2025, eight RC holes for 360 metres were completed to better define the geology and hydrogeology underlying a planned raw water storage facility yet to be built. The results from all this work are expected in the current quarter.
The Company continues to work closely with Nedbank as the Mandated Lead Arranger to coordinate and arrange the project financing. Deep Yellow has now provided the full Tumas 2025 DFS to the Independent Technical Expert covering all works and results carried out up to end March 2025. This information is regarded sufficient to allow them to conclude their due diligence work for Nedbank.
