Green Manganese critical metals flowsheet: process and energy notes for mine planners
Reviewed by Tom Sullivan

First reported on MINING.com
30 Second Briefing
Green Manganese Technologies has completed initial metallurgical test work showing its proprietary hydrometallurgical circuit can recover manganese, nickel, cobalt, and copper from polymetallic nodules in a single integrated process, avoiding Submerged Arc Furnaces, electrolysis, and multi-phase converting. The flowsheet selectively dissolves manganese minerals to release associated critical metals into one solution while converting iron to hematite, creating an additional value stream for iron, titanium, and rare earth elements. Reported recoveries exceed 90% for all four principal metals with energy consumption up to five times lower than conventional pyrometallurgical routes, positioning the process for pilot-scale nodule projects.
Technical Brief
- Hydrometallurgical platform is tailored specifically for manganese-bearing, multi-metal feeds rather than single-ore streams.
- Process chemistry is based on “specialised manganese chemistry” to attack manganese phases while controlling iron behaviour.
- Iron in nodules is deliberately converted to hematite, easing solid–liquid separation and residue handling.
- Hematite-rich residue is positioned as a secondary value stream for iron, titanium and rare earth recovery.
- Flowsheet is explicitly designed to avoid legacy nodule routes that first smelt to a Ni-Cu-Co alloy.
- Green Manganese positions the work as initial metallurgical testwork, forming the basis for pilot-scale trials.
- CEO frames nodules as a “next-generation multi-metal feedstock” incompatible with conventional single-ore smelting technologies.
- As deep-sea collection projects advance toward commercialisation, the company is targeting collaboration on integrated processing solutions.
Our Take
With nickel, cobalt, copper and manganese all in play, Green Manganese’s single-stream recovery concept sits at the intersection of multiple supply-chain pinch points highlighted in our coverage, from Canada Nickel’s Crawford project build-out to EU scrutiny of MMG’s ferronickel acquisition.
An energy consumption reduction factor of up to 5x, if scalable, would materially change the cost curve for polymetallic nodule processing and could undercut some land-based nickel and cobalt projects that currently dominate the 64 keyword-matched pieces in our database.
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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