Optimal Blast Design
Blasting is a common operation in mines (OP/UG). It consists of reducing a massive intact rock to small pieces to facilitate transport.
Blast design has always been a crucial question mark for mining engineers and blasters. Note that the degree of fragmentation depends on the following parameters:
- The rock’s characteristics.
- The properties and quantities of explosives.
- Blast geometry.
- Blast size
- The priming method.
- The initiation sequence.
In the lines below, we are going to deal with the blast design based on type of explosive used.
The following ratios can be used as first approximations in designing blasts. Bear in mind that the ratios will usually have to be adjusted as one learns more about how the particular rock reacts when blasted:
Using ANFO at a specific gravity of 0.82 g/cc
- light rock (2.2 g/cc density) = 28 x diameter
- medium rock (2.7 g/cc density) = 25 x diameter
- dense rock (3.2 g/cc density) = 23 x diameter
Using Slurries, Emulsions, etc at a specific gravity of 1.20 g/cc
- light rock (2.2 g/cc density) = 33 x diameter
- medium rock (2.7 g/cc density) = 30 x diameter
- dense rock (3.2 g/cc density) = 27 x diameter
