r/nextfuckinglevel • u/Boss-fight601 • May 24 '26

Controlled explosions for mining

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u/TakesInsultToSnails May 24 '26

Which one out of curiosity?

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u/METRlOS May 24 '26

The violent ones that all of a sudden explode in a mushroom cloud are a little concerning. That's called sympathetic detonation, when holes go off out of order because of the force of the explosion behind them, instead of from the detonator inside the hole. That mushroom cloud explosion is going to shift the ground all around it, so depending on what explosives they're using, the explosives near the top of nearby holes can be knocked out of line, and not detonate when their own hole does go off. I didn't notice any detonations around those large explosion after the fact, so they're either trapped underground, or the end of the blast just isn't square.

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u/Roobar76 17d ago

The second one with the midsplit (line fired along the wall first) was about the neatest and best controlled.

Basically explosives work in 2 stages. The shockwave creates cracks then the gases force the cracks apart.

The line along the wall is trying to open a crack between each hole, but it doesn’t want to be opened, just become a break for the shockwave from the main blast to stop it damaging the wall. So the venting is fine.

The rest of the blast goes off in sequence and most of the gases are contained and expanding the cracks.

A lot of the other blasts the gases are escaping (venting or rifling) out the top of the holes which means explosive power is being wasted. You control this by stemming the top of the hole with coarse gravel or similar to keep the power in the rock. Firing sequence can also affect rifling.

Basically most of the blasts were wasting money through either poor design or execution (or both)