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

The recovery of copper by leaching techniques has been practiced for centuries. In-situ leaching offers a potentially attractive way to extract copper from the subsurface without costly fragmentation and processing. Applicability of in-situ leaching is limited to deposits where sufficient permeability exists and where the copper and gangue mineralogy is amenable to leaching. This part involves a review of physical and chemical processes that are expected to affect the leaching rate of copper. A fracture network in porphyry rocks can occur naturally or can be induced by fracture stimulation by hydraulic or blasting stress. A key challenge from past projects is establishing uniform contact between the fluid and the formation in fractured environments, particularly if fractures become blocked by gases, gypsum, jarosite and mechanical precipitation during leaching. Hydraulic fracturing can be used for deposits below the water table, whilst blasting or caving can be used for deposits above the water table. The leaching of a copper oxide deposit depends on the strength and volume of sulfuric acid that reaches the ore. The leaching of a copper sulfide deposit depends on an oxidant as well as sulfuric acid reaching the ore.

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