Sleeving blastholes is the practice of creating a liner around drilled blast holes-something typically done in the mining & quarrying industry-before they are charged with explosives. The reasons for doing this often include:
- Stemming water ingress (where water in the blast hole can reduce the effectiveness of water-sensitive explosives like ANFO).
- Preventing the explosives from being ejected from the blast hole into the air or onto the ground by wet, fractured or “hot” ground.
- Ensuring a more efficient release of energy (or “explosion”) from the explosives by maintaining the explosive column’s confinement in the drill hole.
They are usually made from materials that are flexible and strong such as plastic lay flat liners or woven polypropylene. The blast hole is drilled, and the sleeve is usually lowered into the blast hole by hand and sometimes using a sleeving stand to aid the easy and safe deployment.
Once in position, the explosives are loaded into the sleeve, providing some protection against water or other potential negative ground conditions, thereby providing a safer workplace and better blasting results.
In summary, sleeving blastholes is a technique commensurate with the nature of the hazard. Serviceable explosives are maintained, and challenging drilling conditions are better addressed with the use of this technique.
