Case Study:
Reduction of Ground Vibrations by 14% with Blast Size increase by 300%
Location: Certovy Schody Quarry, North West of Czech Republic
Project Type: Surface Limestone Quarry
Products Used:
• E*STAR
• Emulex 1
1. Make vibration results more constant and to keep them below the quarry comfort zone (3 mm/s).
2. Protect the caves and their ecosystems.
The History
The production at quarry Certovy Schody started in 1950. Since that, limestone has been exploited from the quarry on the regular basis. With two interconnected pits (eastern and western) and 1,800,000 tons per year, it’s one of the biggest quarries in Czech Republic.
The most pressing issue for this quarry is historical caves in close proximity of the western pit. Until 2011, only nonelectric detonators were used in this pit. From 2012 to 2014 E*STAR detonators were used, without the modeling. Beginning in 2015, E*STAR detonators with blasting solutions, and later Paradigm modeling, was used for all blasting works.
The Challenges
Nonelectric blasts were generating unpredictable vibrations with a big value spread. When blasting operations get closer, vibrations get higher, and the spread gets bigger. Typical blast parameters are: hole lengths from 15 to 20 m, hole diameters 92 mm, burden 3.3 m and spacing 2.9 m. Charge weight might be a maximum of 27 kg per deck. The request was for the lowest vibration inside the caves – close to stalagmite.
The Austin Solution
Every single blast was run through Paradigm modeling software analysis. The results from the analysis provided the best hole-to-hole, row-to-row, and deck-to-deck delay. Only this procedure can guarantee the lowest possible vibrations inside the caves and ensure their protection.
The Outcome
Using E*STAR electronic detonators with Paradigm modeling reduced vibrations and decreased the spread of values. The average blast vibration reduction was 14% with a 300% blast size increase. Maximum charge per delay interval was increased by 100%.
