Case Studies

Real Varistem® stemming-plug trials from mines and quarries around the world. Each study below measures a specific outcome against the site’s own conventional-stemming baseline. Several are backed by independent university research. See how Varistem stemming plugs perform in real-world conditions.

IMPROVING ANNUAL COST SAVINGS WITH VARISTEM®

INDUSTRY

Underground mine, South America

IMPACT

Unit cost, burden spacing, drilling/explosives consumption

OVERALL EFFECT

Unit operating cost down up to 8.6% (at 1.25m burden); projected annual saving ~USD 300,000.

Widening the burden from 1.1m to 1.25m while holding fragmentation allows the mine to drill and blast fewer holes per block. Unit cost fell from $2.44 to $2.23 per tonne, using Varistem® BP2 plugs.

SENSITIVE AREA BLASTING: DESIGN, MONITORING & BEST PRACTICES

INDUSTRY

Open Pit Mine, South Africa

IMPACT

PPV compliance, monitoring, process

OVERALL EFFECT

Full proximity-blasting lifecycle keeping PPV, noise and airblast below DMPR legal limits.

ERG’s full process for blasting near homes and infrastructure. It covers predicting PPV before the blast, monitoring at seven seismograph stations during the blast, and reporting afterwards, all kept within DMPR legal limits under the Aug-2024 mandatory code of practice.

UNISA RESEARCH

REDUCTION OF AIR BLAST DURING SURFACE MINE BLASTING

INDUSTRY

Quarry, South Africa

IMPACT

Airblast/air overpressure, regulatory compliance

OVERALL EFFECT

Airblast sample mean reduced 9.35% (Station A) and 9.08% (Station B); 134 dB exceedances cut from 67% to 33% (A) and 25% to 0% (B).

Across 27 blasts (15 with Varistem® BP4 plugs, 12 standard), the plugs cut the airblast pressure wave that affects nearby structures. Far fewer Varistem® blasts exceeded the 134 dB limit, with the reduction confirmed at 95% confidence.

Mushwana, 2025 · UNISA

IMPROVING EXPLOSIVES CONFINEMENT WITH VARISTEM®

INDUSTRY

Copper mine, Africa

IMPACT

Velocity of Detonation (VoD), fragmentation

OVERALL EFFECT

VoD of holes with Varistem® plugs was 10.9% higher than those without.

A 10-hole trial compared detonation velocity (VoD) with and without Varistem® BP8 plugs. Holes with plugs ran 10.9% faster on average, a sign of better confinement keeping energy in the hole rather than venting.

DRILL BIT DIAMETER VS EFFECTIVE IN-FIELD DIAMETER

INDUSTRY

Iron ore mine

IMPACT

Fragmentation, charge mass/powder factor, QA/QC

OVERALL EFFECT

A measured in-field diameter of 142mm vs the 127mm bit (≈+15%) drove charge mass per metre up ~25% and lifted powder factor by an estimated ~35%, explaining the oversize and poor fragmentation.

The mine charged its holes to a 127mm bit size, but the holes were actually drilling out to 142mm on average. That gap left most holes undercharged, which was the real cause of the oversize, rather than crew discipline.

IMPROVING FRAGMENTATION & LOADER PRODUCTIVITY

INDUSTRY

Gold mine, West Africa

IMPACT

Fragmentation, loader productivity, cost-neutrality, and environmental impact

OVERALL EFFECT

D80 6.61% finer; loader productivity +8.7% (PC2000); achieved at net-zero cost.

A 0.5m air deck above the charge cut roughly 10.8kg of explosive per hole at net-zero cost, yet the fragmentation was finer and more uniform. With fewer oversize boulders, loaders dug 8.7% faster (PC2000 fleet).

PRE-SPLIT BLASTING IN MINING, QUARRYING AND CONSTRUCTION

INDUSTRY

Mining, quarrying, construction

IMPACT

Wall stability, overbreak control, slope integrity

OVERALL EFFECT

A practical design-and-audit framework for pre-splits that protect final walls from overbreak and blast damage.

A practical guide to pre-splitting, where a row of lightly charged perimeter holes is fired first to create a clean fracture plane that protects the final wall from overbreak. It combines accepted industry rules with 20+ years of ERG site experience into a step-by-step design and audit method by rock type.

UNDERSTANDING & MANAGING BLAST-INDUCED NOISE, AIRBLAST & AIR OVERPRESSURE

INDUSTRY

Mines & quarries

IMPACT

Airblast, noise, air overpressure, monitoring & compliance

OVERALL EFFECT

A technical reference on what generates blast airblast and how to measure, predict and control it.

A technical explainer on blast airblast: the four ways pressure escapes a hole (air, rock, stemming and gas release pulses), how it’s measured, the dB-to-pressure conversion, and what drives it (charge mass per delay, distance, weather). The key takeaway is that one poorly stemmed or mistimed hole can breach limits, so execution matters as much as design.

VARISTEM® STEMMING PLUG PILOT PROJECT

INDUSTRY

Underground platinum mine, South Africa

IMPACT

Advance per blast, profitability

OVERALL EFFECT

Advance per blast up 11% (2.46m to 2.82m); net value ~R58,000 per panel per blast. Financial improvement of R 1.91 billion.

Over a month at a platinum mine, replacing tamping cartridges with Varistem® plugs improved advance per blast by 11% (2.46m to 2.82m).

REDUCING FLYROCK BY IMPROVING ENERGY RETENTION

INDUSTRY

Coal mine, South Africa

IMPACT

Flyrock, safety, energy retention

OVERALL EFFECT

Despite an average SDoB (0.53) predicting violent flyrock, throw stayed within ~100 m; behaviour was a controlled "heave," not flyrock.

Flyrock is rock thrown beyond the blast’s safe zone. By its Scaled Depth of Burial (0.53), this 218-hole blast near a farm should have thrown rock violently. Instead, it heaved and settled within roughly 100m, which the team attributes to Varistem® retaining energy in the rock.