EXPLOSION CUT MAKING METHOD Russian patent published in 1995 - IPC

FIELD: mining industry. SUBSTANCE: explosion cut making method involves drilling blastholes varying in depth. The blastholes are drilled perpendicular with the stope plane in several parallel horizontal rows. The blastholes in the first (lower) row are drilled closer to one another, and they vary in depth. Shorter blastholes are positioned so that the end- face parts of their charges are on a plane passing through end-faces of charges in the upper rows including end-faces of charges of the last row of blastholes. The longer blastholes are drilled to the depth of blastholes in the last row. In the plane of location of the third row of blastholes counting from the first (lowest) row, both sides of this row, auxiliary blastholes are drilled spaced from the last blastholes in the row a distance equal to 0.9-1.1 the spacing between the main cut blastholes in the row. An additional row of blastholes is drilled above the last row of blastholes. The depth of blastholes in this additional; row is 0.85-0.95 of depth of blastholes in the last row. Blowing up starts with exploding charges in the shorter blastholes in the first row. Charges in the auxiliary blastholes are exploded just before blowing up those in deeper blastholes in the first row. These latter charges are exploded simultaneously with charges of blastholes in the additional row. EFFECT: higher efficiency. 3 dwg