VARIABLE-DIAMETER BOREHOLE CHARGE FOR LOOSENING OF ROCKS Russian patent published in 2016 - IPC F42D1/08 

FIELD: mining.

SUBSTANCE: blast borehole structure comprises air chamber and variable-diameter charge arranged there above. Said charge comprises two various-length elastic sleeves sealed from the bottom ends and fitted one into another to cover the explosive charge preset height. Outer sleeve features the sizes larger the borehole diameter while inner sleeve features the size smaller than the borehole diameter. Inner sleeve bottom part with the charge is located at the bottom charge upper part. Air shell is formed between said outer and inner sleeves. The fuse is arranged at bottom charge upper part of at top charge lower part.

EFFECT: reduced rock mass wreckage height, lower costs of medium hardness rocks.

4 dwg