Varistem® Stemming Plugs

Varistem® is a stemming plug for mining, quarrying, and civil blasting applications. The stemming plugs increase energy retention and utilization during blasting, resulting in a range of benefits:

Improvement in Fragmentation
Reduction of Flyrock
Reduction of Noise and Airblast
Downstream Productivity Gains
Significant Cost Saving

Varistem® is available for all blasthole diameters ranging between 1.75 inches (45mm) to 10 inches (251mm).

80% Reduction in flyrock distance

Varistem helped a coal mine minimise fyrock, noise and airblast, leading to improved retention of blast energy.

87% Improvement in cast

A coal mine saw a vast refinement in cast gain in a split blast test, showing Varistem's effectiveness.

14%+ Crusher throughput

Varistem plugs improved fragmentation, loading, haul cycle times, and crusher throughput.

+$10M per year in value

A manganese mine saw huge gains in both lumpy and low grade manganese, from Varistem.

$1.45M savings p/a

An iron ore mine saw a reduction in waste blasts by using Varistem, saving millions each year.

8% Gain in loading rates

A metalliferous mine saw the immediate impact of Varistem with improved fragmentation.

How does Varistem® improve energy retention and utilization?

Varistem® stemming plugs are manufactured through a process called dip moulding. This process, in combination with the material type, makes the Varistem® plugs flexible with a high tear strength. When a blast is detonated, an initial pressure shockwave is released that precedes the burning front of the explosion.

Due to Varistem®’s flexibility and high tear strength, once this initial shockwave energy exerts force on the plug, it is forced upwards into the stemming material, and creates a temporary pressure seal in the blasthole. As a result, more of the shockwave energy/explosive gas travels into the microfractures in the surrounding rock, weakening the rockmass.

The initial shockwave is quickly followed by the burning front of the explosion, which destroys the Varistem® stemming plugs. But as a result of the rockmass being weakened by the improved retention of the initial shockwave energy, more of the blast energy travels into the rockmass (even though the Varistem plugs are destroyed in the process).

We work on a coal mine in South-Africa with many challenges. Our most important priority is keeping our surrounding community safe, and fully comply with the law regarding flyrock and airblast. We finally found support from the ERG Team that is assisting us with the Varistem product, approved by the DMRE. Since trailing these plugs, we saw a significant difference in our blast quality and our ability to control accountability in the way we can now manage the final stemming and having that confidence in a product that works. Excellent service and products.

I worked for Overlooked Group at Dorstfontein East Coal Mine and have recently undergone an exercise using Varistem product as an addition to blasting application to reduce noise/airblast and to improve explosives energy retention in the blast block. The product showed immediate improvement of air blast up to 12% without changing any other blast parameters. Blast performance also improved as a result of good energy retention and produced better cast performance, fragmentation and as a result we could reduce powder factors with by almost 15% and still achieve similar results.

I work for Mota-Engil Guinea as a drill and blasting Manager. I recently used Varistem® Blasting Plugs from ERG Industrial for improving blast efficiency in our mining operations. The experience lead to significant improvements in rock fragmentation and operational cost savings. Exceeded our expectations

Any mining operation can benefit from the innovative products ERG Industrial offers, such as the Varistem plugs. ERG Industrial is a pleasure to deal with and will optimise blasting practices in a mine through a structured consultative approach

I have used ERG Industrial's Varistem Blasting Plugs on my quarry. Gomes Sand has seen significant improvements in the end result of the lasted product after implementing this product.