Rainer Kerber - F.C. Nuedling Natursteine GmbH & Co KG, Germany
Hossein Tudeshki - Chair for surface mining and international mining, Clausthal University of Technology, Germany
Thorsten Rebehn - Clausthal University of Technology, Germany

Natural stones are the most significant raw material worldwide on a quantity basis. In extraction operations, drilling and blasting technology is mainly employed to break the rock free from the hard rock mass. When the appropriate blastholes are being pierced in a quarry, lineal deviations in these boreholes often occur. One of the main reasons for this is that the drill passes through rock layers of differing hardness as well as difficult, incidental geological circumstances like seams, fractures and shear faces. These lineal deviations generate problems with the subsequent blasting such as flying rock and excessive vibrations which again pose a threat for employees and company equipment. Based on a practical survey, drilling technology will be investigated and described with regard to blasthole directional stability in this report to hand.