On July 9, 2024, Millennial Potash Corp. ("MLP", "Millennial" or the "Company") earned a total 70% interest in the shares of Equatorial Potash Pty. Ltd. which, through its Gabon subsidiary Mayumba Potasse SARL, holds 100% of the Banio Potash Project.
Summary:
Deposit Type
The deposits of the Banio Project are classified as evaporites within the Congo Basin, part of the larger Aptian salt basin that stretches across equatorial West Africa. They can be considered as primary sedimentary rocks.
The Congo Basin is part of the passive continental margin of West Africa that formed during the Late Jurassic to Early Cretaceous breakup of Gondwana (North America, South America, and Africa), (Brownfield and Charpentier, 2006; Chen et al., 2013). Evaporitic salt deposition occurred during the late Aptian (113 Ma to 125 Ma ± 1 Ma) throughout the basin in a large steadily and relatively evenly subsiding sub-sea-level basin. The basin was fed by seepage inflow from the proto-Atlantic (Pedley et al., 2016). The Walvis Ridge, formed by the migrating Tristan da Cunha hot spot, restricted circulation from the open marine ocean to the south, and the Cameroon Fracture Zone limited the northern extent of the Aptian salt basin (Brownfield and Charpentier, 2006).
Within the Rock Salt Formation of the Congo Basin, ten sedimentary evaporite cycles (I to X) have been identified whose mineralogy are consistent with typical brine evolution models (Pedley et al., 2016). These cycles are consistent with rapid periods of sea water inflow and protracted evaporation resulting in the precipitation of salts. A cycle, from bottom to top, generally consists of a basal shale or clay layer, a layer of rock salt (halite), a mixture of halite and carnallitite, and sometimes an end member of bischofite or tachyhydrite (de Ruiter, 1979), Figure 7.6). The potash seams are predominantly primary carnallitite except in certain areas where it has been transformed into secondary sylvinite (Pedley et al., 2016).
Potash Mineralisation in the Banio Project
To evaluate the extent of potash mineralisation within the Banio Project area, the three potash exploration drill holes (Ba-001, Ba-002 and Ba-003) and the six historical hydrocarbon exploration drill holes (Banio-1, Banio 2, Banio 3, Banio 4, Banio-5 and BATC-1) were used.
The down hole geophysical logs allowed the identification of overburden, clay, and anhydrite dominated rocks. Within the evaporite sequence it was used to distinguish between rock salt layers, carnallitite seams, interlayered rock salt and carnallitite, tachyhydrite layers, and interlayered carnallitite and tachyhydrite. The geophysical logging data of the historic Banio drill holes was insufficient to obtain a robust estimate of the carnallite content of the seams, even for drill holes where natural gamma ray, density, and calliper logs were available. This is likely due to the use of an inadequate drilling mud when intercepting the evaporite sequence.
Potential Potash Deposit
The available exploration drill hole results and the seismic interpretations enable definition of a potash deposit consisting mainly of carnallite over most of the southern part of the licence area.
The good correlation of potash seams and horizons between the Ba-holes in the NW and the Banio holes in the SE for Cycles VII to V, combined with observations from elsewhere in the Congo Basin, suggest that wherever the seismic interpretation shows a salt bearing section (>300 m), there is a reasonable prospect of finding similar potash seams or horizons when drilling within this area.
Mineable Potash Seams in the Banio Project
Although numerous potash seams and horizons have been identified it is only possible to provide accurate information about thickness and grade of the seams and horizons that are present in drill holes Ba-002 and Ba-003. These drill holes have assay data from cores and high-resolution natural gamma ray logs that have been used to verify depth and thicknesses of the identified seams and horizons.
For the other drill holes only an approximation of the seam and horizon thicknesses from the geophysical logs can be made. Information on grades is limited to extrapolation of assay data from Ba-002 and Ba-003, or published data from other projects in the Congo Basin.
Considering that the seams and horizons defined may be used for Mineral Resource estimation, only potentially mineable seams that can be processed to a Muriate of Potash (MOP) product are discussed. To be considered as potentially mineable via solution mining the following cut-off parameters were applied to the carnallitite and sylvinite seams or horizons from Ba-002 and Ba-003:
• Carnallitite: seam thickness had to be >2.5 m when single, and >1.25 m when other seams are present within a 5 m vertical distance, and carnallite content >47%; and,
• Sylvinite: seam thickness had to be >2 m and the sylvite content >16%. Combined sylvite/carnallite seams (e.g. Cycle VIII Seam 4 in Ba-003, Cycle VII Seam 14 in Ba-002) have been considered as separate seams.
For the Banio drill holes without assay data, the minimum thickness of a seam or horizon to be considered as mineable is =2 m, with an average natural gamma reading over the section of 65 API to 90 API, depending on the measured maximum intensity from the drill hole. The potential mineable potash seams and horizons will be discussed from top to bottom.