What is Involved in ISR Mining?

Leaching is the process of extracting a substance from a solid that has come into contact with a liquid -  making a cup of tea is an example of the leaching process.

Leaching of minerals from rocks happens naturally in the environment. Groundwater that is either slightly acidic or alkaline will dissolve minerals into solution which are then transported through rock pore spaces and the result is often visible as stains on the outside of a rock. There is much evidence of this in many abandoned copper mines across South Australia and Australia, where there is visible green and blue staining on the rocks and pit walls.

ISR chemistry is the same process; water that has been treated by a lixiviant dissolves a mineral into solution and this mineral is then extracted from the solution by a recovery process at the surface. ISR is below surface extraction not to be confused with existing processes like above surface heap leaching.

Traditionally, ISR mining for copper, gold and uranium have all used a weak acid solution (sulphuric acid). However they have often been ineffective in extracting copper and gold. Recent research by CSIRO and Curtin University has uncovered new developments in benign lixiviant technology, now enabling the effective application of environmentally friendly ISR to a much broader array of metals.

These new lixiviant systems (including glycine, MSA and thiosulphate), are used in a range of existing medical, dentistry and farming industries. Glycine is also commonly used as a food additive.

They are both biodegradable and can effectively recover copper and gold under the right geochemical conditions.

The ISR process more recently is being used in environmental remediation where it is more

commonly called “Pump and Treat”.

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