Group 6’s Dolphin underground phase: design and processing notes for mine teams
Reviewed by Tom Sullivan
First reported on Australian Mining
30 Second Briefing
Group 6 Metals has entered the underground mining phase at its Dolphin tungsten mine on King Island, Tasmania, after processing a record 77,953 tonnes of ore in the June quarter, up from 72,351 tonnes in the previous quarter. Higher-grade underground ore is scheduled to feed the processing plant later this year, following initial open-pit operations. For mine planners and metallurgists, the shift underground signals an impending change in grade control, stope design and plant tuning as the orebody transitions to deeper, likely more complex geometries.
Technical Brief
- Underground access development at Dolphin has commenced, marking transition from surface to subsurface stoping layouts.
- Record June-quarter plant throughput of 77,953 t confirms current comminution and classification circuit stability.
- Incremental throughput lift from 72,351 t suggests debottlenecking of materials handling or mill availability improvements.
- Grade control will shift from bench-based open-pit sampling to underground face mapping and channel sampling.
- Underground phase introduces new geotechnical demands: ground support design, ventilation, and water inflow management.
- Processing more competent underground ore may change crusher liner wear patterns and mill power draw behaviour.
Our Take
Group 6 Metals appears only sporadically in our database compared with larger Australian base‑metal names, so moving the Dolphin tungsten mine on King Island into an underground phase positions it as one of the few advanced tungsten plays in the 1237 Mining stories tracked.
Tungsten shows up in just 37 keyword‑matched pieces across our coverage, far fewer than iron ore or copper, which suggests that a producing underground operation in Tasmania could gain outsized attention from offtakers looking to diversify away from traditional supply regions.
Group 6 Metals was previously mentioned alongside Hillgrove Resources and Caspin Resources in an April 2026 item on underground copper production and exploration, indicating it is increasingly grouped with operators capable of managing complex underground developments rather than as a niche re‑starter of historic assets.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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