Coda Minerals has recovered up to 83.3% of the cobalt remaining after leaching into a concentrate representing just 4% of the residue mass. The result adds a potentially valuable recovery step to Elizabeth Creek, but it remains preliminary laboratory work and is absent from current project economics.
- 83.3% of residual cobalt recovered in best flotation test
- Cobalt concentrate represented 4.0% of residue mass
- Current Elizabeth Creek economics assume no cobalt revenue
- Further re-leach, variability and economic testing required
- PFS modelling and environmental work continue
Flotation captures most cobalt left after leaching
Coda Minerals Limited (ASX:COD) has found a way to collect much of the cobalt currently left behind by Elizabeth Creek’s primary leach, with the strongest laboratory test recovering 83.3% of the cobalt in the leach residue into a concentrate containing just 4.0% of the residue mass.
That is the attractive part of the result. A smaller, cobalt-rich stream could be easier to treat than the full volume of material otherwise destined for tailings. The test used conventional flotation after the whole-ore chloride leach, targeting carrollite, the principal cobalt-bearing mineral at the South Australian copper-silver project.
The result builds on the September leach results, which reported strong copper and silver extraction but average cobalt extraction of 39.7% across representative Emmie Bluff composites. On the current testwork, most cobalt in that material remains in the residue after the primary leach.
Best test improved recovery and concentrate quality
Coda compared two flotation tests. JR009 recovered 73% of residue cobalt into a concentrate grading 1.28% cobalt, with a 5.5% mass pull. JR012, using a different and what the company considers more representative lower-grade residue sample, added a recleaner and polishing grind, lifting recovery to 83.3%, concentrate grade to 1.48% and reducing mass pull to 4.0%.
The test also collected some copper and silver. In JR012, copper recovery was 34.8% into a 1.27% copper concentrate, while silver recovery was 47.1% into a 10.6 grams-per-tonne concentrate. Those metals could provide another opportunity if the concentrate can be successfully returned to the proposed leach circuit, although Coda has not demonstrated that integrated pathway yet.
Cobalt upside remains outside the economic base case
Elizabeth Creek’s published whole-ore chloride leach economics currently assume no cobalt revenue. The Emmie Bluff Mineral Resource contains approximately 23,000 tonnes of contained cobalt, with a further roughly 9,300 tonnes across the Windabout and MG14 resources. Coda’s preferred next step is to re-leach the flotation concentrate through the proposed chloride circuit, potentially avoiding a separate hydrometallurgical plant.
That possibility should not yet be treated as project recovery. The flotation and primary leach results came from different samples and tests, and have not been combined in an integrated demonstration. The company also says any future flotation circuit would require additional capital expenditure not included in Elizabeth Creek’s released economic analyses.
PFS work moves alongside metallurgical testing
Coda is now testing whether regrinding the residue and applying a second 24-hour chloride leach can extract cobalt from the concentrate. Locked-cycle work will assess repeated recycling and refloating, while variability testing will examine performance across additional samples from the deposit. Those results, followed by engineering and economic assessment, will determine whether residue flotation enters future project studies.
Elsewhere in the PFS, Metsim process modelling is materially advanced, flood and comminution studies are materially complete, and the final bore in a six-hole groundwater programme is expected shortly. A greenhouse gas assessment has also begun to support a future Mining Lease Application. The technical work is moving forward, but the cobalt opportunity still has to clear the less glamorous tests of repeatability, cost and process integration.
Bottom Line?
The 83.3% result creates genuine cobalt upside, but its investment significance depends on whether the concentrate can be re-leached economically across representative Elizabeth Creek material.
Questions in the middle?
- Can cobalt be extracted from the flotation concentrate through the proposed chloride leach without requiring a separate recovery circuit?
- Will locked-cycle and variability testing reproduce the 83.3% recovery and 4.0% mass pull beyond the small laboratory batches?
- What capital and operating costs will the additional flotation and concentrate-treatment steps add to the Elizabeth Creek PFS?