Mt Marion lithium expansion and flotation: design and scheduling notes for engineers
Reviewed by Tom Sullivan
First reported on International Mining – News
30 Second Briefing
Mineral Resources has taken Final Investment Decision to expand the Mt Marion lithium operation at Karramindie, Western Australia, with joint venture partner Jiangxi Ganfeng Lithium, adding a new flotation plant and transitioning to include underground mining. The project will shift the site from a solely open-pit, DMS-focused operation towards higher-recovery concentrator flowsheets more typical of hard-rock spodumene plants. For geotechnical and mining teams, underground development will require new ground control regimes, revised dewatering strategies and re-optimised ore scheduling around the expanded processing capacity.
Technical Brief
- Final Investment Decision covers both process plant construction and underground mine capital in a single package.
- Expansion is framed as “significant”, implying multi-year capex and staged construction rather than a debottlenecking tweak.
- New flotation plant will require additional tailings handling capacity and potentially modified TSF deposition strategies.
- Underground transition will necessitate new mine access development, likely declines from current open-pit perimeter.
- Ventilation, secondary egress and underground power reticulation will be new infrastructure classes for the Mt Marion site.
- Integration of underground ore will drive rework of stockpile management, ROM blending and crusher feed strategies.
- Similar DMS-to-flotation upgrades at WA spodumene mines have typically triggered revised water balance and reagent logistics planning.
Our Take
In our database, Mineral Resources’ restart of the Bald Hill lithium mine in WA (coverage dated 18–19 May 2026) alongside this Mt Marion expansion signals a deliberate build‑out of a multi‑asset hard‑rock lithium portfolio in the state, which can give MinRes more optionality in how it feeds downstream converters such as Ganfeng.
Lithium is one of the more densely covered commodities in our Mining corpus (136 keyword‑matched pieces), and Western Australia features heavily in that set, indicating that Mt Marion’s upgrade keeps WA at the centre of hard‑rock supply narratives even as new jurisdictions like the Northern Territory (e.g. Finniss) try to attract capital.
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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