Modern Mining December 2021

STEMMING PLUGS

cheaper than having to do secondary blasting or mechanical breakage,” he says. In some cases globally, Varistem has achieved up to a 25% increase in fragmentation, which in turn reduces crushing costs and increases crusher throughput. Independent studies also show that the

Varistem can increase blast pattern spread by 10% or more, with the same fragmentation for major savings in drilling and explosive costs. Outlook Looking ahead, Preis sees the uptake of Varistem increasing exponentially over the next couple of years as the general sentiment on stemming plugs changes and the significance of proper energy con- finement moves to the fore. “Results speak volumes, and consistently deliv- ering results is the only real way to get rid of a historically negative perception on stemming plugs/ devices. Varistem is consistently producing the results for an ever growing list of customers (in South Africa, Africa and across the world), and this is the start of widespread adoption of devices that improve energy retention,” concludes Preis. 

Historical versus Varistem particle size distribution curves.

Key takeaways  Since mid-2019, ERG Industrial has seen increased uptake of Varistem stemming plugs in the South African mining sector  Local quarries were the first to adopt the technology before mines fol- lowed suit  In September this year, ERG helped a Mpumalanga coal mine to improve cast by up to 82% using the 171 mm Varistem plugs  Using its 171 mm Varistem plugs, ERG was recently able to reduce topsize by 35% and fines by 10% at a metalliferous project in the Northern Cape

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24  MODERN MINING  December 2021