Ore Sorting Success at Heemskirk Signals Potential Cost and Environmental Risks Mitigated

Ore Sorting Breakthrough at Heemskirk

Stellar Resources Limited (ASX, SRZ) has announced compelling results from large-scale ore sorting trials at its flagship Heemskirk Tin Project in Tasmania. Using advanced X-Ray Transmission (XRT) technology, the trials demonstrated a significant uplift in tin grade and recovery, alongside promising reductions in processing costs. This development marks a critical step forward in de-risking the project’s processing flowsheet and enhancing its economic outlook.

The trials focused on samples from the Queen Hill deposit, a key early mining target within Heemskirk. By rejecting approximately half the mass as waste, the ore sorting process upgraded the tin grade from 0.91% to 1.50% Sn; a 1.6 times increase; while recovering 82.4% of the tin. An alternative approach that included both high- and medium-grade product streams pushed tin recovery to 97.2%, with a 1.2 times grade uplift and 21.1% mass rejection. These results provide flexibility to optimize the processing strategy based on recovery versus throughput trade-offs.

Technology and Cost Implications

The XRT ore sorting technology is well established and already in commercial use at the nearby Renison Tin Mine, which contributes nearly 4% of global tin supply. Stellar’s successful scale-up of this technology to Heemskirk’s orebody reinforces confidence in its commercial viability. Importantly, comminution testwork revealed that removing waste material prior to grinding reduces power consumption by 10% for the high-grade option and about 5% for the higher recovery option. This translates into meaningful operating cost savings.

Beyond operational efficiencies, the ore sorting results support a streamlined plant design with lower throughput requirements. This has the potential to reduce capital expenditure significantly, while also decreasing tailings volumes and enabling the use of coarse backfill material in underground mining. The ability to blend grades more effectively throughout the mine life further enhances project flexibility and value.

Ongoing Studies and Next Steps

These findings are being integrated into Stellar’s Prefeasibility Study (PFS), which is progressing alongside ongoing drilling and metallurgical testwork. The company expects to update its mineral resource estimates in the fourth quarter of 2025, incorporating new data from the Queen Hill and Severn deposits. Further metallurgical testing will assess downstream processing performance on sorted material, aiming to maximize tin recovery.

Stellar’s Managing Director Simon Taylor described the trials as a "significant step forward" that de-risks the project and confirms the scalability of ore sorting at Heemskirk. The company’s vision of a low-impact, high-grade tin operation in Tasmania is increasingly supported by these technical advances, which could position Heemskirk as a competitive player in the global tin market.