ELIMINATING DANGEROUS FUME EVENTS
THE CHALLENGE
Explosive gases occur naturally on every blast. Ideally, the by-products are carbon dioxide, hot steam, and nitrogen, all relatively harmless to humans. Non-ideal reactions or positive oxygen balance produce toxic orange and brown Nitrous Oxide (NOx). This occurs when underfueling the explosive mix, degradation due to contact with water or soil contaminants, or when explosives are unconfined, often due to varying blast hole diameters in less competent or preconditioned rock masses.
Our client, a Powder River Basin miner, experienced regular fume events in their large production shots. Soft and wet ground conditions, along with sleeping loaded holes for days or weeks, contributed to these events. To manage fume impacts and comply with the Wyoming Department of Environmental Quality (WDEQ) notice of violation, the mine modified blasts by reducing shot size and scheduling blasts with favorable wind conditions. This was a temporary measure due to the mine’s proximity to public infrastructure. However, this strategy was ineffective, often leading to delayed blasts, proving unsustainable long-term.
SITE PROFILE
• Material: Carbonaceous shale
• Standard Blast Panel Size: 300 holes approx
• Explosives: 50/50 Emulsion blend
• Hole Diameter: 311.15 mm
• Hole Depth: 39.62 m
• Hole Profile: 25-degree angle
THE SOLUTION
In a region with historical fume issues due to explosive, blasting techniques, and ground conditions, multiple solutions, including hole liners, were explored. Traditional flat lay Polyethylene hole liners struggled in deep, angled holes, tearing and ripping easily, making them difficult to deploy, resulting in blockages and operational time loss.
MTi Group developed the BLASTSHIELD™ liner, a high tensile, ripstop internally laminated woven liner, designed to protect explosives from degradation by water and contaminants, and overcome traditional issues of ripping and tearing in angled holes. Using the BLASTSHIELD™ system, the liner was deployed easily and efficiently, with the system heat-sealing the liner to ensure zero leakage while minimizing manual handling.
THE RESULTS
The BLASTSHIELD™ liners had an immediate impact, eliminating fume events by 100% in all lined cast blasts. This allowed the mine to abandon previous blast design modifications and design blasts based on production requirements, independent of wind constraints. Additionally, the mine was able to better match explosives to ground conditions, using ANFO instead of heavy emulsion blends, exerting greater control and achieving better blasting results.
