The Effects of Detonation Wave Collisions on Rock Throw


Cast blasting is the primary means of overburden displacement in a surface coal mine. It serves two purposes; fragmenting the rock and throwing it directly to its spoil pile using explosive energy. Increased throw minimizes costs by reducing the amount of material that needs to be re-handled. Prior studies have shown that by only changing blast hole timing with the same blast design, fragmentation and throw alters. It is necessary in cast blasting to optimize both fragmentation and throw, since larger fragments will require more wasted energy to throw the same distance. In an operating mine in Georgia, an optimum interhole delay for fragmentation has been found by studying timings from 0ms to 45ms. Instantaneous timing between holes increased the throw by over 100 ft, but fragmentation was poor. Shock and detonation wave collision is a potential reason for this increased throw. This paper investigates this optimized inter-hole timing while altering top and bottom column primer time to potentially improve throw while maintaining optimum fragmentation. Timings studied are top initiation, bottom initiation, and top and bottom simultaneously.

Meeting Name

SME Annual Conference & Expo 2017: Creating Value in a Cyclical Environment (2017: Feb. 19-22, Denver, CO)


Mining Engineering

Keywords and Phrases

Blasting; Coal mines; Detonation; Photosensitivity; Piles; Shock waves; Blast design; Blast holes; Cast blasting; Detonation waves; Explosive energy; Georgia; Surface coal mines; Explosives

International Standard Book Number (ISBN)


Document Type

Article - Conference proceedings

Document Version


File Type





© 2017 Society for Mining, Metallurgy and Exploration, All rights reserved.

Publication Date

01 Feb 2017