Drilling of straight holes has had a long term focus. Still a lot can be done to improve the drilling results.
In all quarries and mines drillhole quality should be of interest, not only because of the safety, but also due
to an unrevealed economic aspect. The paper describes less specific drilling and charging, reduced drill steel
costs and higher drilling efficiency, along with better fragmentation, less secondary breaking and better loading
conditions.
The paper is mainly based on the author’s PhD thesis. The paper includes a general description of the deviation
phenomenon and efforts to reduce it. The paper reveals the results from practical tests in the field with varying
bit design, rod design and changed drilling settings, along with other experiences achieved during the work. At
the end a cost estimation example is presented. Boring av Rette Hull Sikkerhet o Ekonomi