Analysis of the Excavation Techniques to Optimize the productivity in an Italian Dimension Stone Basin

The Ossola basin is an important dimension stone producing district in the North-Western Italian Alps, from which different kinds of stones are extracted, mainly pertaining to the granite and gneiss families. After a general information on the geological features of the basin, the exploitation methods and the current blasting practices, comprising also cases of mixed methods (explosive plus mechanical cutting), are described and typical examples are provided. Then, a historical quarry is examined. The main objective of the research aims to assess the excavation technique adopted and, in light of the input data and results obtained from on-site experiments, to verify the possibility of introducing any changes in order to increase the productivity. The main exploitation techniques used for the extraction of hard and abrasive stones are investigated, with particular regard to those currently employed, which are the dynamic splitting and diamond wire cutting, and is qualitatively compared the applicability of alternative techniques. Many data were collected on site, related to the drilling time and to the implement of the dynamic splitting; specific consumption of explosives was evaluated and other parameters that led to the formulation of new proposals for optimizing the production cycle. The most appropriate seems to be the combined use of explosive and diamond-wire cutting, to combine the advantages of both techniques and to increase productivity, also thanks to the possibility of a partial overlapping of the operations that compete one and the other technique.