Stemming length and stemming materials are crucial factors in blasting design, which affect the sustainability of mining (Shi et al., 2023). Among the numerous factors that influence the success of a blast, the length of the stemming which is the inert material used to fill the space above the explosive charge in a blast hole is particularly significant. This article investigates how stemming length affects blast fragmentation, focusing on the ways in which different lengths can alter fragmentation quality and overall blasting efficiency.
Short stemming length
If the stemming is too short, it fails to effectively confine the explosive energy within the hole. This can cause poor fragmentation, resulting in larger rock pieces due to the premature and uncontrolled release of energy. Additionally, inadequate stemming can lead to increased flyrock and ground vibrations, raising safety concerns and diminishing the blast’s efficiency.
Optimal stemming length
When stemming length is properly calibrated, it helps contain the explosive energy, ensuring that more of it is directed into the surrounding rock mass. This improves fragmentation, producing a more uniform distribution of particle sizes and minimizing the generation of oversized fragments.
Long stemming length
On the other hand, using too much stemming material can hinder energy transfer. While it may help contain the blast, excessive stemming can absorb energy that would otherwise contribute to breaking the rock, leading to less effective fragmentation and a greater risk of generating blocky or oversized pieces.
The foundational work of Langefors and Kihlstrom (1963) emphasized the importance of stemming length in achieving efficient fragmentation. Their research showed that improper stemming could cause significant variations in fragment size and distribution, underscoring the need for precise control of this parameter.
Reference
Shi, X., Zhang, Z., Qiu, X., & Luo, Z. (2023). Experiment Study of Stemming Length and Stemming Material Impact on Rock Fragmentation and Dynamic Strain. Sustainability, 15(17), Article 17. https://doi.org/10.3390/su151713024
