Heemskirk Ore Sorting Lifts Tin Grade 2.4x, Recovers Up to 95% Metal

Ore Sorting Breakthrough at Heemskirk

Stellar Resources Limited (ASX: SRZ) has unveiled compelling ore sorting test results from its flagship Heemskirk Tin Project in Western Tasmania. The recent trials, conducted on samples from the Severn Deposit, demonstrated a remarkable increase in tin head grade from an average of 0.70% to 1.65% Sn, a 2.4 times uplift, while rejecting over 64% of the mass. This was achieved using X-ray transmission (XRT) technology, which separates ore based on density, effectively removing waste material before processing.

Such a significant grade uplift, coupled with an 84.7% tin recovery rate, suggests that ore sorting could dramatically improve the project's economics by reducing the volume of material fed into the processing plant. This not only lowers operating costs but also has the potential to reduce capital expenditure by enabling a smaller plant footprint.

Optimizing Recovery and Cost Efficiency

Further refinement of the sorting process, by blending high and medium grade product streams, pushed tin recovery to an impressive 95.3%, while still achieving a 33.1% mass rejection and a 1.4 times grade uplift to 0.99% Sn. These results indicate flexibility in balancing recovery rates and mass rejection to optimize both output and cost efficiency.

Importantly, variability testing across six samples from different parts of the Severn orebody confirmed the broad applicability of ore sorting technology throughout the deposit. This consistency is critical for scaling up the process in future mining operations.

Strategic Implications for Heemskirk Development

Stellar’s Managing Director Simon Taylor highlighted the transformative potential of these findings, noting that ore sorting could reduce capital outlay and operational costs while increasing metal production. The company’s ongoing Prefeasibility Study (PFS) is focused on integrating ore sorting to enable higher mining rates, reduce tailings storage requirements, and implement grade streaming strategies over the life of mine.

The PFS is progressing alongside drilling and metallurgical programs, with three rigs currently operating around Severn and Queen Hill deposits. These efforts aim to refine the flowsheet and validate the economic benefits of ore sorting at scale.

Environmental and Operational Benefits

Beyond cost savings, ore sorting offers environmental advantages by reducing the volume of waste material processed and stored as tailings. This aligns with Stellar’s commitment to developing Heemskirk in an environmentally responsible manner. Additionally, the potential to use crushed waste as backfill material in underground mining could further enhance operational efficiency and sustainability.

Looking Ahead

Stellar’s ore sorting results build on earlier positive testwork from 2017 and 2018, now validated across a broader sample set. The company plans a larger-scale program to optimize sorting parameters and evaluate trade-offs between mass rejection and tin recovery. These efforts will feed directly into the PFS, expected in the second half of 2025, which will provide a clearer picture of the project's commercial viability and development pathway.

With Heemskirk already ranked as Australia’s highest-grade undeveloped tin resource and third globally, these technological advancements could position Stellar Resources as a key player in the global tin market, particularly as demand for tin in electronics and green technologies grows.