METHOD OF UNDERGROUND LEACHING OF PRECIOUS METALS OUT OF ORES Russian patent published in 2009 - IPC E21B43/28 

FIELD: mining.

SUBSTANCE: invention refers to mining of minerals by means of chemical-technological methods. The method of underground leaching of precious metals from ores of water-permeable gravel deposits and auriferous gravel, and also from residual soils consists in boring a system of injection and evacuation boreholes, in pumping oxidant and leaching solution into an ore bearing bed, in withdrawing production solution, in processing it with known methods of cementing and sorption. Processing of ore is performed in two stages. During the first stage ore bearing bed is oxidised with oxygen by means of watering it with softened circulating solution saturated with oxygen containing gas. The injection solution is preliminary cleared from suspension of salts of hardness and impurities. During the second stage copper ammine and thiosulfate are added to evacuation solution, pH and contents of sulphite is corrected with sulphuric acid and ammonia. Precious metals are oxidised and leached with this mixture.

EFFECT: implementation of ecologically clean thiosulfate leaching of precious metals under bed conditions.

5 cl, 5 ex