What are the four stages of blast design process?

To design a simple blast, a few rules may be sufficient to understand the same. The process will include the following:

• Assessing the rock mass blastability preferably in terms of its density and p-wave velocity that define its impedance. There have been attempts to classify rock mass for blasting in terms of rock factor or rock constant “c” by umpteen number of authors.
• Fixing of the drill diameter which is generally dictated by the bench height and production requirements. However, if a drill with prefixed diameter is already in place, it will constraint the design process.
• Selection of explosive by knowing its characteristics like its density (ρ_e) and velocity of detonation (c_d). This will be determined by the rock type. A broad criterion is to match the explosive impedance (c_d × ρ_e) with the impedance of the rock, i.e. the product of density of rock and p-wave velocity (ρ_r × c_p).
• Predicting the initial fragment size through established equations of mean fragment size (k₅₀) and uniformity index (n) of the fragment size distribution.

Source: «Flyrock in Surface Mines» by K. Raina