The quarry in Pajęczno has a pit that is closing its borders, and so, to keep up with production requirements, they had to open a new one. The new pit is neighboring the old one, but due to land ownership issues, it cannot be joined together. Wheel loaders scraped the overburden, and the first opening blast was scheduled for the 14th of July. The first bench height was planned to be 9 meters. Considering that the structures were only 307 meters away, the Austin Technical team decided to blast the first opening on half the target bench height. A signature hole was fired a day earlier, which provided them with the starting point for firing the best initiation sequence, as well as the timing for the first blast.
Products used were APB 50×350 mm 0.9 kg boosters, 16 kg of Hydromite 70 (per hole), and E*STAR detonators. Stemming was 2.5 m with a total of 36 holes. The results of the blast were promising, without flyrock, and vibrations measured on the structures were 40% lower than predicted and well within the boundaries set by Polish regulations. Based on the collected data, the team was able to predict and better optimize the next shot, which was bigger, but the vibrations were not registered by the nearby structures, which means they were too low to cause damage or have any effect on the structure.
Ondrej Cermak, Blasting Manager for Central Europe, says, “The entire process showcased Austin’s expertise and professionalism and was an excellent job done by the Polish team, who blasts every day in this quarry.”
Link to Blast https://youtu.be/5q-ixftyI0E
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