Stellar Resources Advances Tin Recovery at Queen Hill, Boosting Heemskirk Prospects

Significant Metallurgical Gains at Queen Hill

Stellar Resources (ASX:SRZ) has reported a meaningful leap in tin recovery at its Queen Hill deposit within the Heemskirk Tin Project, Western Tasmania. Metallurgical testwork by ALS Metallurgy Burnie shows a pathway to exceed 70% tin recovery, up from around 62.7% in prior studies. This improvement is driven by targeted process enhancements including ore sorting, gravity regrind, and magnetic separation, which together boost both recovery rates and concentrate quality.

The upgraded flowsheet has been designed with input from Geoff Beros, ex-Chief Metallurgist at the nearby Renison Tin Mine, which itself boasts recoveries near 80%. The Queen Hill concentrate grades between 42% and 49% tin, aligning well with smelter requirements, and the process modifications reduce reliance on fine recovery circuits by improving coarse cassiterite liberation.

Flowsheet Innovations and Cost Efficiencies

Key to the recovery boost is the integration of ore sorting that rejects up to 50% mass at low tin loss, enhancing feed grade and reducing grinding energy demand. The addition of a gravity regrind step to 53 microns improves liberation of tin minerals locked in gangue and sulphides, lifting coarse gravity circuit recovery to 55-65% of total tin. Magnetic separation selectively removes siderite and other gangue minerals, improving flotation performance and cutting reagent consumption, notably Styrene Phosphonic Acid, a major cost driver.

These technical gains also promise environmental benefits through lower tailings volume and potential reuse of sorted rejects as backfill. The company notes that further optimisation, including adjustments to sulphide flotation and additional magnetic separation steps, will be explored in the upcoming Definitive Feasibility Study.

Commercial and Project Development Implications

Stellar's Managing Director Simon Taylor emphasised the significance of the results, stating they materially de-risk the project and enhance early-stage economics. The Queen Hill deposit is scheduled early in the mine plan, so improved recoveries could have an outsized impact on initial cash flow and project valuation.

Reflecting market interest, the company has begun preliminary, non-binding discussions with potential offtake partners focused on concentrate specifications. This commercial engagement complements ongoing technical work, including resource drilling at Severn and mine planning at Queen Hill.

The updated Severn Mineral Resource Estimate is expected in the June quarter, with the Prefeasibility Study release rescheduled to early Q3 2026. These milestones follow a recent 41% increase in Queen Hill resource, underscoring the project’s growing scale and quality.

Technical Rigor and Future Workstreams

The metallurgical testwork program is comprehensive and JORC-compliant, with samples derived from ore-sorted composites reflecting realistic mill feed grades. Analytical methods include XRF and ICP techniques with stringent QA/QC protocols overseen by industry experts. The program represents the first time ore-sorted Heemskirk material has been processed through an enhanced flowsheet, delivering robust data to underpin project development.

Beyond metallurgy, Stellar is advancing mining design, process plant engineering, and environmental baseline studies, including a mining lease application for tailings storage. The company signals ongoing efforts to refine recovery pathways and reduce operating costs ahead of the Definitive Feasibility Study.