What is the difference between line drilling and presplitting drilling?

Answer 1

1. Pre-splitting holes are charged, whereas line-drilling holes are not.
   • Pre-splitting holes contain less explosive than the rest of the holes in the blast area.
   • The blast holes directly adjacent to the line-drilling holes are charged to about 50% of that of the rest of the blast area.
2. The diameter of the holes in pre-splitting tend to be much larger than those in line-drilling.
   • Pre-splitting holes diameter ranges from 50mm - 100mm for civil engineering purposes while larger holes are used (some larger than 300 mm) for mining.
   • Line-drilling holes usually have a diameter less than 75mm.
   • Pre-splitting spacing is about 10-20 times the hole diameter.
   • Line-drilling holes are spaced about 2-4 times the diameter of the hole.
3. The holes in line-drilling are spaced much closer together than those of pre-splitting.