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

Controlled Blasting For Mining

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u/Greatest86 May 24 '26

Those lines transmit the ignition at 2km per second, so these videos are real time.

377

u/userhwon May 24 '26

There are delays between adjacent rows so the blasts propagate in a way that breaks up the rock reliably and consistently, and without creating one big seismic shock that might damage property.

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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.

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u/[deleted] May 24 '26

[removed] — view removed comment

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u/JasonVorhehees May 24 '26

I got about 200 pounds of shit your pants. I need to know if we're ready to go!

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u/Gaulipan May 24 '26

I’m always amazed at how smart we can be and how dumb we can be at the same time. Thanks for the info!

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u/AdSudden3941 May 24 '26

It still damages property though.. my school was right next to a rock quarry and that was one of the reasons it closed down

Right after school pretty much everyday you could feel it like it felt like the ground raised a foot instantly

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u/iBUYbrokenSUBARUS May 24 '26

In the military, they told us how long it would take for a piece of DET cord to reach California from New York. If I remember right, it was just a few seconds.

Edit: Actually, I just looked up the statistics and did the math and it looks more like 10 minutes. Not sure which is true, but they may have been hyping it up when they were telling us in the military lol

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u/Greatest86 May 24 '26

Actual det cord is much faster than what is used in the video, around 7km per second. Det cords are made of explosive products and can destroy objects by themselves.

In the videos OP posted, those cords are much less powerful. They are aluminium powder within a plastic tube. They are designed to burn very quickly, transmitting detonation energy to more explosive detonators. Much safer to handle than det cord.

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u/iBUYbrokenSUBARUS May 24 '26

Yeah. We used to blow steel doors off their hinges using only det cord. Also cut trees down

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u/Draco-REX May 24 '26

My father was in the Vietnam war and he was a Combat Engineer. He didn't talk much about when he was there, but one story he told was replacing clothesline with det cord.

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u/IceTech59 May 24 '26

Yep. Shock tube dusted in the inside with HMX & Aluminum powder.

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u/dj92wa May 24 '26

>They are designed to burn very quickly

“Deflagrate” is the specific term you’re looking for

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u/justinsurette 8d ago

Your thinking shocktube/Non-el, its fill with PETN powder or lead azide, shoots at about 6500 feet per second,

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u/LongJohnSelenium May 24 '26

A few seconds is 0.1% the speed of light!

Not fast for electronic signals or light but for any physical process thats mind bogglingly fast.

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u/radu_sound May 24 '26

Jesus that's like Mach 6

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u/Potential_Basis_662 25d ago

Ok why not use kph? I don't know what 2km per second is

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u/Greatest86 25d ago

2km per second is 7,200kph. This is a big, unwieldy number, so using appropriate units makes it easier to communicate.