METHOD OF UNDERGROUND METAL HEAP LEACHING FROM PERMAFROST ROCK Russian patent published in 2006 - IPC E21B43/28 

FIELD: mining industry, particularly for dissolving minerals other than hydrocarbons by an alkaline or acid leaching agent.

SUBSTANCE: method involves drilling injection wells in alluvial deposit block and boring extraction well in center thereof to extract the production solutions; injecting working reagent solutions via the wells and extracting the production solutions; performing fracturing of central part of productive horizon by blasting thereof from extraction well in parallel to horizon borders; forming crushed zone and cracked zones in bottom rock in lower part of extraction well for production solution accumulation; supplying liquid explosive through extraction well into cavities and cracks formed by fracturing operation; initiating camouflet blasting in the cavities to break productive horizon rock; injecting hot working reagent solution through injection well into the productive horizon. The working reagent solution includes additives, namely easy solving alkali or other metal salts having low eutectic temperature not reacting with the working reagents and with possible intermediate products of reaction. The additives are mixed in amounts providing concentration near saturation.

EFFECT: possibility to create thawed working zone for following metal heap leaching before operation termination along with work performing in any season.