Blastability of rocks under permafrost conditions

Abstract

1. For normal working of the bottom the linear dimensions of the borehole grid in frozen rocks should be reduced 13% and the explosive ratio increased 28% compared to the same rocks in a normal (thawed) state. 2. When reissuing the standards the tables of explosive consumption should be supple-mented by the explosive ratios for frozen rocks according to Table 1 of this article. 3. The adverse effect of permafrost on the blastability of rocks is observed not only with respect to working the bottom but also to crushing of the rock mass. Therefore, in frozen large-block rocks producing an increased yield of oversize, the required explosive ratio can substantially exceed the value needed for working the bottom. The value of the explosive ratio for the required crushing of the rock should be established by experimental explosions for the specific mining conditions.