Tuesday saw Thor Mining (LSE:THR) rise after revealing positive drilling results at its part-owned Kapunda in-situ recovery (ISR) copper project in South Australia.
Three holes were drilled, and two screened wells installed, to complete initial hydrogeological investigations at the asset – in which EnviroCopper has entered a two-stage agreement to earn a 75pc stake. Thor, in turn, holds a 25pc interest in EnviroCopper with rights to increase that stake to 30pc.
Not only did this work reveal that the project’s water table is quite shallow, but it also confirmed connectivity between screened intervals along its predominant fracture directions. These are both critical requirements for the ISR process, which centres around a chemical process called ‘leaching’. In layman’s terms, this involves dissolving minerals underground in a solution before extracting them at the surface. As ISR is much cheaper and quicker than actually building a copper mine, EnviroCopper believes that the technique can bring lower-grade projects into economic territory.
Elsewhere on Tuesday, Thor said the first round of drilling at Kapunda had revealed that the fracture zone contains significant copper mineralisation thought to be amenable to the ISR process. Indeed, the pilot hole encountered 66m at 0.27pc copper including 5m at 0.72pc copper and 11m at 0.54pc copper. Meanwhile, the two additional holes intersected 8m, 23m at 0.49pc copper to end of hole and 22m, 6m at 0.47pc copper to end of hole respectively.
EnviroCopper’s next stage of work includes large-scale column leach recovery tests leading on to a full-scale field trial.
Thor’s executive chairman Mick Billing said: ‘It is very exciting to have confirmation of both consistency of mineralisation and possible hydrogeological connectivity along strike in the facture zone. This adds considerable weight to the potential for a successful ISR operation in due course. ‘It is also pleasing to note that the preliminary copper grades are above the average for the resource. We are very keen to have laboratory assays to confirm these, and also to provide any gold values, as gold is most unlikely to be picked up in portable XRF readings.
‘These holes were drilled on the very southern tip of the main resource area, and previously conducted IP surveys further south show additional chargeable anomalies which should be investigated to see if they contain additional mineralisation, which could significantly extend the resource.’
As we have written before, by achieving production at Kapunda, EnviroCopper hopes to demonstrate ISR’s operational viability in the copper market and take the technology to other projects.
Aided by historical mining data and environmental and hydrogeological work, EnviroCopper has estimated Kapunda contains an ISR-amenable inferred copper resource of 119,000ts. As announced in April, the company has also been able to recover gold from samples taken from the project and work to ascertain whether it can establish a resource for the precious metal is ongoing.
Before commercialisation, EnviroCopper must complete a pre-feasibility study and a definitive feasibility study at Kapunda. It will also have to meet any necessary environmental, social, and regulatory requirements and secure financing. Handily, its $2.8m government-issued research grant will support it in these efforts- indeed, the firm expects these funds to take the project through to demonstration of feasibility.
Once progress has been made at Kapunda, EnviroCopper will move on to Moonta - its second 75pc-held project. Moonta is located around 160km north-east of Adelaide within the historical copper triangle of South Australia, where around 300,000ts of copper were mined and processed between the 1860s and 1920s.
Although it is an earlier-stage project than Kapunda, Moonta is also thought to be a much larger opportunity. In August 2019, EnviroCopper announced an initial inferred resource estimate for the asset of 66.1MMts grading 0.17pc copper. This translates to 114,000ts of contained copper considered amenable to ISR, taking EnviroCopper’s business-wide managed resource inventory 233,000ts. However, this initial figure was formed from the analysis of just 164 drill holes at Moonta. This lead to the identification of three copper deposits, called Wombat, Bruce, and Larwood. A further 308 holes already drilled over these deposits will feature in future resource modelling once quality assurance has been completed, providing an obvious opportunity for upside. What’s more, all three deposits remain open along strike or at depth – providing EnviroCopper with a chance to identify mineralisation beyond that already discovered.
Author: Daniel Flynn
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