Bench Blasting Design for Optimum Recovery of Blocks in Dimension Stone Quarries: A Case Study of Crushed Rock Industry, Supare-Nigeria

Dimension stone quarry is believed to be type of mining operation that always result to low recovery since what is expected from the extracting operation is a cubical block with no fracture. It is noticed that majority of the damage in the natural blocks are always from poor extraction method. In aggregate quarry, series of work have been done on powder factor that gives economical blasting. In this research work, breaking factor is used in place of powder factor since breaking is required not powder. The aim of this research work is to establish a standard breaking factor for bench blasting in dimension quarries that will improve recovery. Two cases were considered. In case 1, gun powder is used for basal cutting. Of the seven patterns considered, pattern3 gives highest recovery (70%) with breaking factor of 23.15g/m 3 (i.e. 5kg of Gun powder for (6 by 6 by 6) m bench design). In the case 2, dynacord is used for basal cutting. Of the four patterns considered, pattern 2 gives highest recovery (55%) with breaking factor of 15g/m 3 ( i.e. 3.24kg of explosive for (6 by 6 by 6) m bench design. Keywords: Extracting, powder factor, aggregate, recovery, breaking factor