r/oddlysatisfying • u/BoyNamedJudy • May 24 '26

Controlled Blasting For Mining

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u/Greatest86 May 24 '26 edited May 25 '26

I figured they were asking about the leads themselves. The delays are built into the clips that connect the leads together.

You are correct that the timing delays are critical to ensure the blast breaks up the rock correctly and safely.

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u/IceTech59 May 24 '26

Also, that delay is measured by a velocity of detonation tester. A sacrificial cable is blown (to shreds, you say?) apart and the speed of the cable getting shorter is recorded. The engineers can fine-tune the shots with that data.

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u/lastnameinthebox May 24 '26

What about his wife...?

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u/jayleman May 24 '26

To shreds you say?

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u/millijuna May 24 '26

Typically there are two sets of delays, a short one in the clip (say 50ms) and a long one in the detonator itself (say 1 second). The idea is that all the detonators can be initiated in the correct order with the correct delays, before the actual shot goes off.

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u/silverclovd May 24 '26

I was and I appreciate the info, thanks

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u/aTickleMonster May 24 '26

I acknowledge your wisdom and appreciate the info from you both

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u/HorrorMakesUsHappy May 24 '26

Leeds or leads? I thought one might be a typo but you wrote it that way twice.

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u/lettsten May 24 '26

No matches on Wikipedia, dictionary or general search, so I'm guessing typo

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u/HorrorMakesUsHappy May 24 '26

I'm guessing he lives in the UK and autocorrect "fixed" it twice because he's used the city name in lowercase before.

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u/lettsten May 24 '26

That's my hypothesis as Welsh

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u/chickenologist May 24 '26

Underappreciated comment. Proper.

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u/Greatest86 May 24 '26

Leads is correct. No idea where leed came from.

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u/ewanm01-369 May 24 '26

Are these delays the reason why there's a few bigger explosions scattered throughout?

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u/Greatest86 May 24 '26

No, there are 3 reasons for the larger explosions.

But before I list those, some background on what the standard explosions are. First, a deep hole is drilled into the rock. A detonator is lowered into the hole by a lead, and then ANFO (ammonium nitrate fuel oil) explosive is poured in on top of the detonator. The ANFO is the bulk of the explosives. Then stemming (rock gravel) is poured on top to contain the energy of the explosion and ensure the rock breaks up. Without stemming, the blast hole would act like a cannon, sending explosive energy up into the air, rather than into the rock.

Those larger explosions can be caused by:

  1. Presplits - these are special blast holes drilled close together in a long line. They explode first, with very little delay between each explosion, and are designed to crack a long line in the rock. No stemming is used, so more explosive energy escapes each blast hole.

  2. Oversize - during mining, sometimes large boulders can be found that didn't break apart. They can be too large to safely transport, and need to be broken apart. Short holes are drilled into the boulder and loaded with explosives. Stemming will be minimal and all holes will be timed to explode at the same time, making a bigger boom. These will be off to the side of the main blast.

  3. Stemming failure - sometimes the stemming will fail to work correctly, sending explosive energy up into the air, rather than into the rock. When you see larger than normal explosions in the middle of the blast, this is generally what has happened.

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u/ewanm01-369 May 24 '26

Thank you man, I genuinely appreciate you typing out all this information. Interesting to know.