Leaching tests move Thor a step closer to ISR copper solution at Kapunda

Thor Mining has made a metallurgical test work breakthrough at the Kapunda copper project in South Australia, indicating in-situ recovery (ISR) may be a viable extraction solution at the historic mine.

The results show two days of bottle roll leach testing using a biodegradable amino acid as a lixiviant can recover up to 78% of copper, Thor said.

The company has a right to earn up to 60% of Kapunda by funding test work and feasibility study activities on the project over the next two years and, in February, Thor announced an initial inferred resource of 119,000 t of copper, grading 0.25% Cu, as part of this.

Kapunda is a town built up around Australia’s copper mining history and lays claim to not only being the first established profitably operating copper mine but also being the saviour of South Australia’s financial woes in the 1840s.

The ISR resource estimate was built on the back of historic drilling data taken from 1965 through to 2008 at Kapunda.

A series of bottle roll tests over seven days was conducted on four drill core samples by the company’s cooperative research centre partner, CSIRO. This work is part of a A$2.85 million ($2.10 million) grant from the Australian Commonwealth Government for the Kapunda In-Situ copper and gold recovery trial.

The Deep core sample (0.27% Cu) produced the best results, coming back with recovery of 78.48% after just one day, while the Top sample, which graded 0.103% Cu, had a 60% recovery after seven days.

Interestingly, the lixiviant used was glycine, an amino acid typically used in food and pharmaceutical industries.

Mick Billing, Executive Chairman of Thor, said while laboratory conditions were not a full simulation of field processing, these were still positive results.

“The success with glycine, a very benign substance, is an important step forward. Other lixiviants are also being trialled, and we look forward to these results when available,” he said.

If Thor is successful in proving Kapunda ore can be extracted by such means, it is likely to lead to other existing deposits becoming potential ISR candidates.