METHOD FOR DOWNHOLE LEACHING OF GOLD FROM COMPLEX-STRUCTURE DEEP-LYING PLACERS Russian patent published in 2020 - IPC E21B43/28 

FIELD: mining.

SUBSTANCE: invention relates to mining industry and can be used in combined development of complex structure deep-lying placers by means of mechanical extraction and underground leaching of sands. Method of downhole leaching of gold from complex structure deep-lying placers includes drilling of wells, supply through them to productive formation of activated leaching solutions, collection of productive solutions, subsequent sorption extraction of gold from productive solutions, preliminary formation of drainage openings, local extraction of gold-bearing mineral mass from rich zones. At detection of rich zone of productive formation during testing of drilling material of wells containing coarse gold, wells are expanded by auger mining of rich zone with auger with subsequent extraction of sands for gravity concentration. A drain tube with a perforated bottom part is installed in the center of the well, resting on the raft through the heel with guides for flexible perforated pipes, which are penetrated by conical end head pieces into the zone with average gold content of the productive stratum. To reinforce the walls of the well, a mesh frame is installed – with annular perforated pipes and with stiffening ribs – on productive formation thickness. Gravel is located in mesh carcass at level of perforated lower part of drain tube. Concentrated solution of leaching reagents is fed through annular perforated pipes into zones with average content of gold of hard-to-remove forms. In zones with low content of gold, preparative carbonate-peroxide solution is supplied through wells. Technological pause is maintained for diffusion leaching of gold in zones with average gold content and oxidation of productive formation in zones with low content of gold, then, a solution with complexing agents of weak concentration and pumping of generated productive solutions through flexible perforated pipes and drain pipes of wells is pumped into productive formation through wells.

EFFECT: increased extraction degree of gold of gravity-enriched forms and chemically bound forms.

1 cl, 3 dwg