METHOD OF SEALING IMPERVIOUS SCREEN UNDER WATER RESERVOIRS AFTER OPEN PIT MINING Russian patent published in 2015 - IPC E21B33/138 

FIELD: mining.

SUBSTANCE: into the lower part of the impervious man-made screen containing dolerite rocks, the cement grouting is pumped, based on sulphate resistant or calcium aluminate cement with hardener (2% CaCl₂) under pressure greater than hydrostatic, through the wells drilled from underground excavations. In the cement grouting the filler is used as mill tailings with a fraction of 0.1-0.25 mm, corresponding to fine sand. It is kept till hardening. After hardening the resulting rock-cement layer of the impervious screen is tamped with local injections of synthetic resins under pressure, less than the pressure of fracture of rock mass of mining protective pillar left under the screen. And the cement grouting is pumped under pressure of 0.7-0.8 MPa, and local injections of synthetic resin is carried out at a pressure of 0.5-0.6 MPa. The synthetic resin is used as hydro-active compositions based on LT-70 with the addition of a solvent - dimethylformamide in an amount of 20-25%.

EFFECT: increased strength and increased of impervious properties of the screen when filling the open pit.

6 cl, 2 dwg