ASX-listed Sovereign Metals has started an infill drilling programme at its Kasiya rutile/graphite project, in Malawi, to support ongoing technical studies.

Aircore drilling, supported by push tube/diamond core and hand auger drilling, will upgrade part of the current mineral resource estimate (MRE) planned for Stage 1 production from the indicated to the measured category under the Joint Ore Reserves Committee (2012) code.

The drilling is planned to infill the southern part of Kasiya, specifically around previously designated pits proposed to provide ore feed in the first eight years of the project's planned production schedule. Ore reserves in these areas are expected to convert from the probable to proven category.

"Our infill drilling programme will target areas of Kasiya where we expect the first seven to eight years of production to come from. The programme design was overseen by the Rio Tinto-Sovereign technical committee, which again illustrates the benefits of the Rio Tinto partnership since their initial investment in July 2023,” Sovereign MD Frank Eagar said on August 12.

An offset 200 m x 200 m programme has been designed, which will result in an average drill spacing of 142 m. The offset spacing has the advantage of allowing analysis of geology and grade continuity in both orthogonal and diagonal directions.

The drilling programme will consist of more than 250 aircore holes for more than 5 000 m, with an average depth of 20 m, as well as more than 250 hand auger holes for more than 750 m, with an average depth of 3 m.

Thirty push tube or diamond core holes will also be drilled, providing samples for geotechnical analysis and verification sampling with an average depth of 20 m.

Further, several 3-m-deep pits will be drilled to obtain detailed rutile grade information from the upper profile and provide additional geotechnical information.

All samples will have both rutile and graphite assayed by offsite laboratories in South Africa. Results of the drilling programme and subsequent resource upgrade are expected in early 2025.

Sovereign believes Kasiya is already the world's largest rutile deposit and second-largest flake graphite deposit, with more than 66% of the current MRE in the indicated category.

The current MRE defines broad and contiguous zones of high-grade rutile and graphite, which occur across a large area of more than 201 km². Rutile mineralisation is concentrated in laterally extensive, near-surface, flat "blanket" style bodies in areas where the weathering profile is preserved and not significantly eroded.

Graphite is depleted near the surface, with grades improving at depths generally more than 4 m to the base of the saprolite zone, which averages about 22 m.

Sovereign's 2022 drill programme at Kasiya used push tube core holes to infill and convert inferred mineralisation into the indicated category. The consistency and robustness of the geology allowed for an efficient conversion of this previously inferred material on a near-identical one-for-one basis to the indicated category.