M. A. Meretukov, Research Adviser, e-mail: mamer@inbox.ru

Hydrometallurgical extraction of copper by in situ leaching needs to refer to disciplines such as solution chemistry, hydrology, geology, geochemistry, and rock mechanics. Both physical and chemical parameters must be integrated to successfully predict in situ leaching performance. In this review, data from past copper in situ leaching projects are assembled, with a focus on recovery with and without prior permeability enhancement of the ore body. To give a historical example, in the United States a small portion of copper was produced through in situ leaching of low-grade ores that were left behind from earlier mining activities. The present-day projects on realisation of in situ leaching at US deposits are presented. These projects take into account permeability, hydrogeological conditions and selective leachability as the most critical parameters as regards ISR, and must be defined at the stage of evaluation and exploration. Morphology and depth of mineralisation, thickness, grades, and distribution of mineralisation are also important factors when it comes to ISR projects. In the case of copper, the solution used is weak sulphuric acid, similar to the one used for typical heap leaching of copper oxides. The pregnant leach solution is then processed at a solvent extraction-electrowinning plant.

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