Weir ENDURON Optimil vertical stirred mills: circuit retrofit gains for process engineers
Reviewed by Tom Sullivan
First reported on International Mining – News
30 Second Briefing
Weir has launched the ENDURON Optimil vertical stirred mill to cut energy use and operating costs in fine and ultra-fine grinding circuits as ore grades fall and power prices rise. The mill uses a vertical, high-intensity stirred design with a small footprint, targeting regrind and tertiary duties where conventional ball mills struggle with efficiency. For process engineers, the key play is retrofitting into existing circuits to reduce specific energy consumption per tonne and improve grind size control without major layout changes.
Technical Brief
- ENDURON Optimil uses a vertical, high-intensity stirred mechanism with a compact, tower-style shell.
- Mill design targets fine and ultra-fine particle size distributions typical of modern complex ores.
- Stirred configuration is engineered to maximise media–slurry contact, improving breakage rates at lower residence times.
- Layout is intended to retrofit into existing grinding circuits with minimal civils or structural steel changes.
- Weir is positioning Optimil specifically for regrind and tertiary duties rather than primary grinding stages.
- Machine is configured to operate with smaller grinding media sizes than conventional ball mills in similar duties.
- OEM support offering includes process circuit optimisation around the new mill rather than standalone equipment supply.
- For flowsheets with multiple regrind stages, Optimil is pitched as a drop-in replacement to rationalise mill count.
Our Take
Across our recent Mining coverage, Weir repeatedly links comminution upgrades (HPGRs, liners, screens) to brownfield optimisation rather than greenfield builds, suggesting these ENDURON Optimil mills are likely being pitched as retrofit options to sweat existing grinding assets harder.
The 2026-09-07 piece on ENDURON HPGRs for Zijin’s Golden Ridge operation in Ghana shows Weir already using high‑pressure and stirred‑media technologies in tandem, which signals a strategic push to own the full energy‑efficient grinding flow sheet rather than selling stand‑alone machines.
Comments from Weir’s capital and process leaders in the 2026-10-14 and 2026-09-09 articles emphasise water and process control as design variables, so Optimil vertical stirred mills will likely be marketed not just on power efficiency but on tighter circuit controllability and water‑use integration.
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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