When using NONEL the explosive in the hole can be initiated from the bottom in an efficient way. Detonating cord initiates the explosive from the top of the hole and may, when using relatively insensitive explosives as ANFO and certain emulsion explosives it can cause dead pressing.
Top initiation with detonating cord often causes flyrock as the stemming is destroyed when the detonation wave goes through it.
When initiating with NONEL the surface activation is well ahead of the initiation of the explosive in the blasthole. A combination of U 500 in the blasthole and Îľclip 42 on the surface most often gives the result that the whole round is activated before any rock movement starts.
Published on Oct 26, 2008