Determination of specific charge minimizing total unit cost of open pit quarry blasting operations

The value of specific charge in open pit quarry blasting processes considerably affects the efficiency of the blasting. When a high value of specific charge is used in a blasting process, the material resulting from the blasting will have a finer dimension. Costs of explosives and drilling will be increased due to high specific charge value; however, costs of subsequent processes such as loading, hauling, crushing, and boulder crushing will be reduced due to finer dimension of the material. Determination of specific charge value that will minimize total unit costs of the open pit quarry operations will ensure the performance of blasting process in the most economical manner. In this study, certain blast tests have been carried out in three different limestone quarries. Unit costs of explosives, drilling, loading, hauling, crushing, and boulder crushing at each site were determined, and specific charge values minimizing total unit cost of the operations were separately determined for each worksite. Afterward, optimal specific charge values were interrelated according to uniaxial compressive strength values of the rock.