The velocity of detonation (VOD) is a key parameter that influences blast fragmentation and potential dilution during rock blasting in mining operations.
Excessive burden (distance from blasthole to free face) can lead to delayed rock displacement, causing higher borehole pressures and gas penetration. This increases ground vibration and damage, potentially leading to unplanned dilution.
Larger blasthole diameters with fully coupled explosives transmit more energy to the rock, causing greater damage and dilution. However, decoupling (air/water gap) can reduce damage by damping the energy transmission.
Stress waves and explosive gases both contribute to rock fracturing and fragmentation. Optimizing energy distribution through factors like VOD helps minimize unplanned dilution.
To sum up, excessive burden, large boreholes, and unstable detonation can increase unplanned dilution by causing excessive rock damage. Carefully controlling blast design parameters like VOD is important for managing fragmentation and dilution in mining blasts.
