Varistem

Varistem® plugs are innovative stemming devices designed to enhance energy retention and utilization in blasting operations across mining, quarrying, and civil engineering projects. The design and functionality of these plugs play a pivotal role in optimizing the efficiency of blasting activities, significantly improving the operational outcomes in terms of fragmentation, reduction of flyrock, noise, and airblast while generating downstream productivity gains and cost savings

The Technology of Varistem®

The Varistem® is crafted through a dip moulding process that imparts exceptional flexibility and high tear strength to these plugs. This manufacturing method is crucial as it contributes to the plug’s resilience and effectiveness during the blasting process

Mechanism of Action

When an explosive charge is detonated within a blasthole capped by a Varistem plug, the initial shockwave generated by the detonation is met with the robust yet flexible barrier formed by the plug. This barrier, momentarily, does not allow the high-pressure gases to escape, forcing them downwards into the rock instead of prematurely releasing them into the atmosphere

The stem plug’s prime function is to increase the retention of this explosive energy within the blasthole for a longer duration. By containing the explosion’s initial shockwave energy and the subsequent hot gasses, the plug ensures that more energy is used in breaking and weakening the rockmass around the blasthole. This happens in two phases:
 
1. Initial Shockwave Containment: The Varistem® plug is pushed upwards when the shockwave from the blast exerts upward force, temporarily sealing the top of the blasthole and preventing the escape of gases.
  
2. Energy Channeling: After the initial shock, the burning front of the explosion destroys the plug, but by this stage, much of the energy has already been transmitted into the rock, effectively fragmenting it more efficiently

This improved energy retention directly correlates with better rock fragmentation and a reduction in flyrock, since the energy is channeled into the rock rather than being wasted. These mechanics of energy utilization are critical in blasting operations near sensitive structures or populated areas, where minimizing environmental impact is paramount

Benefits in Practical Applications

The utilization of Varistem® stemming plugs in blasting operations brings multiple advantages:
– Enhanced Fragmentation:
Better energy utilization leads to finer and more uniform rock fragmentation, which can significantly improve the loading and crushing stages in mining operation.
– Reduced Flyrock:
By improving blast confinement, Varistem® plugs minimize the occurrence of flyrock, which enhances safety and compliance with regulatory standards.
– Noise and Airblast Reduction:
The containment of blast energy also reduces the noise and airblast levels emitted during blasts, which is vital for operations close to communities and sensitive environments.
– Economic Efficiency:
Improved blasting efficiency leads to lower overall operational costs due to reduced explosives use and better control of blast outcomes. This efficiency can translate into significant cost savings over the life of a mine or quarry.
– Environmental Considerations:
Being able to control the blast more precisely also means less environmental disturbance, which is increasingly important in projects subjected to stringent environmental regulations.

Conclusion,

Varistem® stemming plugs represent a significant innovation in blasting technology, providing numerous operational benefits through enhanced energy retention and utilization. This technology not only improves the efficiency and safety of blasting operations but also contributes to more environmentally friendly and cost-effective project executions.