The effect of blast hole stemming length to rockpile fragmentation at limestone quarries

摘要

In this study, the effect of stemming length on rockpile size distribution is investigated. Fourteen blasting rounds with ten holes each are test blasted. In the first group of test eleven blasting rounds were blasted where stemming length was 3 m long, and three groups of blast rounds with stemming length of 4.5 m long were tested at the same limestone quarry of Konya cement factory. In these test blasts average holes length were ll m long and diameter of holes were 89 mm. After the trial blasts rockpile size distribution was measured with standard "compare photo" method and verified by Split Desktop software results. The analysis of measurements showed that large size boulder generation was increased with increase in stemming length. For instance, +70 cm size fragments were increased one and half times by increasing stemming length from 3 m to 4.5 m. It has proved that the increase in high percentage of boulder formation means the cost of crushing, grinding and hauling will be increased as well as increased time loss. Evaluating blast efficiency resulted in important economical findings for cement sector.