The effect of Drilling and Blasting Performance on Fragmentation in a Quarry and Time for Loading, Secondary Breakage and Crushing

Small-scale mining operations are characterized by a large variety of equipment availability and a high level of operational flexibility. Mine planning is usually scarce or absent in small quarries in Brazil, and mine management generally focuses on daily operations. As a result, analysis of the effects of unit operations, such as blasting, over the whole mining process is often neglected. The goal of the following project was to study the effect of production blasting on loading and hauling times, secondary breakage times and primary crushing times at the Experimental Mine of the Research Center for Responsible Mining of the University of São Paulo, Brazil. The operations analyzed included blasts that performed: under the average operational standard, defined in this paper as Case 1; according to quarry standards, defined in this paper as Case 2. In order to establish the effects of blasting on the downstream process, three key performance indictors (KPIs) were used: - the time taken to load the truck, when there is the need for material selection (tt); due to the fact that we do not have an operational baseline, the increase in time can’t be established, meaning that we must content ourselves with comparing the mean time in each scenario; - the average time used for secondary breaking machinery (tf); - the time required for the primary crusher to fully process the load of a single truck (tc). The results obtained indicate correlations between the coarseness of the blasted material and theses operational times. Solutions are suggested and evaluated for the improvement of the small-scale mining process.