Coda Minerals Hits 94% Copper Recovery Across Elizabeth Creek as PFS Advances
Key Takeaways
- Four representative Emmie Bluff composites averaged 94.4% copper and 95.9% silver extraction at 24 hours, matching the Scoping Study targets of 94.8% Cu and 98.2% Ag and validating the preferred whole-ore chloride leach process ahead of the PFS.
- Peak extractions of 97.2% copper and 99.7% silver were recorded, with the process also performing effectively on a low-grade proof-of-concept sample at 0.40% Cu, returning 90.0% Cu and 86.8% Ag extraction.
- Cobalt extraction averaged 39.7% and exceeded 50% in two samples — yet cobalt revenue is assumed at zero in the published base-case NPV7 of $2.25 billion and IRR of 56%, meaning any cobalt recovery is pure financial upside.
- Site water from Elizabeth Creek produced a 0.7% improvement in copper and silver extraction and a 6.6% improvement in cobalt extraction versus tap water, reducing a key operational risk and potentially improving project economics.
- Flowsheet selection between the whole-ore chloride leach base case and a flotation-based alternative is expected within weeks, with Ausenco engaged as principal process engineering consultant and comminution test work nearing completion.
Chloride leach process delivers near-scoping study extraction rates across Elizabeth Creek
Coda Minerals (ASX: COD) has completed preliminary variability test work on its whole-ore chloride leach process at the 100%-owned Elizabeth Creek Copper-Silver Project in South Australia, with results reinforcing confidence in the preferred processing pathway ahead of the Pre-Feasibility Study (PFS). Four representative Emmie Bluff composites averaged 94.4% copper extraction and 95.9% silver extraction at 24 hours (post-wash), with peak extractions reaching 97.2% copper and 99.7% silver. These figures are consistent with Scoping Study estimates of 94.8% Cu and 98.2% Ag.
Cobalt extraction averaged 39.7% across the four representative composites, with peak extraction exceeding 50% in two samples. Notably, cobalt is excluded from the published base-case economics, meaning any cobalt recovery represents pure upside to the project’s financial case.
Testing also included a direct comparison using Elizabeth Creek site water versus fresh tap water. Site water showed no detrimental impact on the chloride leaching process and, due to its natural salinity and higher chloride content, may actually improve metal extraction. Over the full leach duration including the wash step, site water produced a 0.7% improvement in copper and silver extraction and a 6.6% improvement in cobalt extraction relative to tap water.
It is important to note that all results described here are derived from laboratory-scale batch tests and remain preliminary. They should be considered indicative under the stated laboratory conditions, not a definitive measure of final metallurgical recovery.
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Variability test results at a glance
| Composite Sample | Cu Grade (%) | Cu Extraction 24hr | Ag Extraction 24hr | Co Extraction 24hr |
|---|---|---|---|---|
| DD26EB0050_Upper | 1.28% | 87.0% | 90.8% | 34.2% |
| DD26EB0051_Upper | 0.63% | 97.2% | 99.7% | 51.4% |
| DD25EB0046_Merged | 1.36% | 96.9% | 97.7% | 51.7% |
| DD26EB0050_Lower | 2.27% | 96.4% | 95.3% | 21.5% |
| DD25WIND0004_Upper (Windabout) | 1.11% | 93.4% | 96.8% | N/A* |
*Cobalt data unavailable for Windabout sample due to mass imbalance between fluid and solid assays. The company is repeating the test to confirm cobalt recovery. Note: DD26EB0051_Lower (Cu grade 0.40%) was deliberately selected as a very low-grade proof-of-concept sample and is excluded from the representative average. It returned 90.0% Cu and 86.8% Ag extraction, confirming the process extracts metal effectively even from low-grade feed.
Key extraction summary across the four representative Emmie Bluff composites:
- Average Cu extraction: 94.4%
- Average Ag extraction: 95.9%
- Peak Cu extraction: 97.2% (DD26EB0051_Upper)
- Peak Ag extraction: 99.7% (DD26EB0051_Upper)
- Windabout Cu extraction: 93.4%
- Cobalt average across four representative composites: 39.7%; peak 51.7%
What is whole-ore chloride leaching and why does it matter?
Whole-ore chloride leaching is a processing method that uses a saltwater-based (chloride-rich) solution combined with injected air (air sparging) to promote the oxidation of copper-bearing sulphide minerals, dissolving copper, silver, and cobalt into solution. The process operates at near-neutral pH and elevated temperature (around 90°C).
The key distinction from conventional flotation is the end product. Traditional flotation produces a copper concentrate that still requires smelting and refining elsewhere, whereas whole-ore chloride leaching can produce refined metal products, such as copper cathode and silver doré, more directly from the ore. That simplification has significant implications for project economics and operating flexibility.
The term “variability” testing refers to the practice of running leach tests across samples with different mineral compositions and head grades, rather than just the best-case ore. Ore deposits are never uniform, so testing across the full range of mineralogy builds confidence that the flowsheet will perform consistently across the full mine life, not just under ideal conditions. That consistency is what reduces technical risk ahead of a PFS.
One particular challenge at Elizabeth Creek is carrollite, the primary cobalt-hosting mineral. Carrollite has a tight crystal lattice structure that resists oxidative leaching, and it hosts cobalt in the 3+ oxidation state, which is harder to keep in solution once dissolved. This explains why cobalt extraction remains lower and more variable than copper and silver, and why Coda is actively pursuing further test work to improve cobalt recovery.
A validated flowsheet that holds up consistently across mineralogy variations is a meaningful de-risking milestone. For investors following the PFS, these results provide growing technical support for the preferred processing route.
For readers wanting foundational context on the asset before diving into metallurgical detail, our dedicated guide to the Elizabeth Creek project overview covers the resource scale, historical development milestones, and the strategic rationale behind Coda’s processing approach.
Cobalt upside adds a free option to the base case
A 50% extraction rate from an excluded revenue stream
Coda’s published base-case economics, which include a pre-tax NPV7 of $2.25 billion and an IRR of 56%, assume zero cobalt revenue. Every gram of cobalt the process can extract and sell is incremental to those figures.
Two samples from the variability programme already exceeded 50% cobalt extraction. The average across the four representative Emmie Bluff composites was 39.7%, and Coda is actively working to improve that figure through adjustments to leach chemistry and physical feed properties. The company is also testing concentration technologies that may be applied to the leach residue, including magnetic separation and traditional flotation, to generate a cobalt concentrate suitable for further processing. Downstream cobalt product identification work is also underway.
CEO Chris Stevens
“Cobalt provides a further opportunity. Our published whole-ore chloride leach base-case economics exclude cobalt revenue, yet these tests achieved more than 50% cobalt extraction in two samples. That gives us a strong reason to pursue the additional value cobalt could bring. Our focus is now on establishing a practical, economic route to capture that potential.”
What the base case already looks like
For context, here are the key Scoping Study economics that form the foundation for the ongoing PFS:
- Pre-tax NPV7: $2.25 billion
- IRR: 56%
- Average annual production: 31.4kt copper and 1.4Moz silver
- Mine life: 15.5 years
- Cobalt revenue assumption: $0 (zero)
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PFS advancing across multiple technical fronts
What comes next
Coda is progressing the Elizabeth Creek PFS across multiple technical workstreams simultaneously, with metallurgical work advancing alongside resource assessment, geotechnical, groundwater, tailings, environmental, and mine planning studies. Near-term milestones include:
The Elizabeth Creek PFS workstreams span resource assessment, geotechnical investigation, groundwater drilling, tailings design, and mine planning, with Ausenco engaged as principal process engineering consultant to advance chemical modelling in parallel with the metallurgical programme.
- Comminution test work (crushing and grinding) — expected to be completed in the near term, informing design of crushing and grinding circuits
- Waste-rock characterisation and flood modelling — near-term completion expected, informing waste-rock management and flood condition assessment
- Groundwater drilling at Emmie Bluff — work is well advanced on Coda’s deepest production bore at the deposit
- Process engineering modelling — Ausenco has been engaged as principal process engineering consultant, with chemical modelling of reagent recyclability underway to confirm key inputs and process operating costs
- Flowsheet selection between the whole-ore chloride leach base case and a flotation-based alternative with an Albion hydrometallurgical circuit — this decision is expected in the coming weeks
- Downstream test work — finalising solvent extraction efficiency assessment and identifying optimal products for zinc and cobalt
Once a final flowsheet selection is made, more formal variability test work utilising larger samples will commence. The flotation backstop option is under concurrent testing in Adelaide and could, if successful, allow development of the project with a potentially significantly reduced capital cost through a smaller downstream processing circuit.
Project scale context
To anchor the scale of what is being studied, the Elizabeth Creek project’s total mineral resources as reported in Table 5 of the announcement are:
- Total mineral resources: 65.5Mt, hosting 705,800t contained copper, 33,000t contained cobalt, 28Moz contained silver
- Emmie Bluff (primary underground deposit): 40.2Mt @ 1.27% Cu, 569ppm Co, 16.8g/t Ag, 0.17% Zn — with 95% of contained Emmie Bluff metal classified as Indicated Resource
- Located in the Olympic Copper Province, approximately 100km south of BHP’s Olympic Dam copper-gold-uranium mine
CEO Chris Stevens
“These results add momentum to Elizabeth Creek. High copper and silver extraction across a broader range of samples strengthens our confidence in the preferred chloride leach process, while the encouraging site-water results bring the testing closer to the conditions relevant to the project.
“For shareholders, the significance is the growing body of evidence supporting the next stage of development studies. We are bringing test work and process modelling together to establish plant requirements, assess costs and select the final PFS flowsheet. This is tangible progress towards defining how Elizabeth Creek could be developed…”
Ready to Explore the Elizabeth Creek Copper-Silver Investment Case?
Coda Minerals’ whole-ore chloride leach process has now demonstrated near-scoping study extraction rates across multiple ore types, with average copper and silver recoveries of 94.4% and 95.9% respectively — and cobalt upside that is entirely excluded from a base-case NPV of $2.25 billion.
With the Pre-Feasibility Study advancing across multiple technical workstreams simultaneously, explore the full Elizabeth Creek project overview at Discovery Alert to understand the resource scale, processing strategy, and the development milestones shaping this emerging South Australian copper project.