SUMMARY: MREL (Mining Resource Engineering Ltd) tested stemming movement and ejection velocity. The longer time to stemming movement and the lower stemming ejection velocity means more blast energy is retained in the bore hole. Energy is directed into the rock, and not lost into the air. There is better fragmentation, less flyrock, and a reduction in noise. Using VARI-STEM® with standard rock stemming, stemming movement was slowed 100% and stemming ejection velocity was reduced 44%.
This extensive report shows the blast containment achieved with the Varistem allows pattern spread for major drill cost savings. Holcim Cement conducted this study at their quarry in St. Genevieve, MO. This facility is the largest cement producing plant in the US, producing over 4 million metric tonnes of cement per year.