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Illustration how sub-laving stoping looks like
1.Drilling an undercut with top hammer 2.Drilling the full length of the stope with Wassara 3.Extra sub-level with top hammer drilling method

When mining adjacent to the ore boundary, the straightness of Wassara guarantees both improved ore recovery and minimal dilution.

Improved blast results

In sub-level stoping, the holes are generally just a few meters apart and some of the holes are adjacent to both the foot wall and the hanging wall. If deviation occurs, it causes a decrease in ore recovery, an increased amount of dilution, and less homogenous fragmentation. In the worst case this could result in a freezed blast.

In other words, the accuracy of the blast holes is the most important aspect in a successful blast. Wassara creates straighter blast holes than any other production drilling method. It is therefore the best method to turn a carefully planned drill and blast design into reality.

No need for undercuts

When conventional drilling methods are used for sub-level stoping, with long distances between the levels, it is common to drill an undercut to avoid the risk of high blast hole deviation. However, an undercut is both costly and time consuming since it literally turns one stope into two. With Wassara there is no need for undercuts since this technology guarantees the necessary accuracy for all sub-level stoping distances. In other words, Wassara improves the productivity as well as the profitability from increased ore recovery and decreased dilution.


1. Drill design
2. Hole deviation with top hammer drilling
3. Deviation results in dilution and ore loss