Rock Blasting - Archive File

[megalomania]

Pyro
Frequent Poster
Posts: 104
From: Danbury,CT,U.S.A
Registered: MAR 2001
posted 05-12-2001 04:28 PM
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I have a problem, a few hundred pound problem. You see, there's a huge rock that I need to get rid of and I don't think a sledge hammer would do it. I was wondering if anyone knew about how to get a large enough hole into the rock to put in a charge large enough to crack it.Also, any added info. on rock blasting would be appreciated.Thanks alot.-Pyro


Anthony
Moderator
Posts: 2306
From: England
Registered: SEP 2000
posted 05-12-2001 04:56 PM
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If you've got a mains supply near by you could easily drill at leats a 1/2" hole in it which should break it. If not (and you don't have a very good battery drill) you'd probably have to mud cap it, you'd need more explosives but effort required is much less


kingspaz
Frequent Poster
Posts: 347
From: UK
Registered: SEP 2000
posted 05-12-2001 05:03 PM
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couldn't a shaped charge be used to crack a big hole in it? then another charge could be placed inside. if the rock is sandstone or something wouldn't astrolite soak in enabling the rock itself to be detonated in a similar manor to when astrolite has been poured onto soil.


FadeToBlackened
Frequent Poster
Posts: 201
From: Hell
Registered: MAR 2001
posted 05-12-2001 05:26 PM
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Personally i wouldn't want to use astrolite (well, not on a rock anyway hehe) because of the hydrazine. I think i read something somewhere about NM with ammonium hydroxide. Im not sure how this works, though.


ALENGOSVIG1
Moderator
Posts: 766
From: Vancouver, Canada
Registered: NOV 2000
posted 05-12-2001 11:01 PM
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Ok, i think it would be best to use the "snake hole" method. That is when you dig a hole underneath the boulder.
For a 3 ft diameter rock, .75 lbs, for a 4ft diameter rock, use 2.00 lbs, for a 5ft diameter rock, use 3.00 lbs. For the larger boulders, if you were to mud cap you would need twice as much explosives.



EP
Frequent Poster
Posts: 108
From: USA
Registered: APR 2001
posted 05-13-2001 12:16 AM
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From what I have read (a blasting manual for agricultural purposes) it said you dont even need to drill holes if you dont have the equipment. It would make things easier, but is not nessecary. Either dig a hole under it as ALENGOSVIG1 suggested, or use the method I read about for when you cant drill. Just place the explosive on the largest centralized crack/indentation. This was written with dynamite in mind, so ANFO would not be adequate.



Pyro
Frequent Poster
Posts: 104
From: Danbury,CT,U.S.A
Registered: MAR 2001
posted 05-13-2001 10:30 AM
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Thanks for the info. guys, I really appreciate it but can someone lay down a detailed description on what to do because all of your idea's sound good but were very vague.Thanks again-Pyro


Anthony
Moderator
Posts: 2306
From: England
Registered: SEP 2000
posted 05-13-2001 11:42 AM
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Isn't the snake hole method intended to lift the rock out of the ground whole(ish)? With ANFO's low brisance it'd probbaly just locate the rock a few feet away

[Tended Tripod]

This idea may not be as fun, but my dad told me that he used to break large bolders by heating them with a bonfire around it, and then dousing it with cold water. The temperature difference cracked the rock all over, and the rock could then be moved in pieces.

Sooooo, I was thinking you could use a huge amount of thermite on top of the rock, and then when its done burning, shoot it with a garden hose. If thats not available, get as large a supersoaker as you can and empty a couple of gallons onto it.

This sounds kinda K3\/\/L|$|-| but it would be fun to watch the whole rock just fall apart.

[DBSP]

You're right the idea is kinda kewlish but it could be midified to be more effective. Heat the rock by burning a large fire around it then flush it with water, then just after it has been chilled smack it with a kg of ANFO. The rock should scatter quite easily because of all the crack in the rock.

[zaibatsu]

Or use the hannibal method - water (or was it wine) is placed into the cracks of bolders, overnight the water freezes and expands, cracking the rock.

[Sonny Jim]

Try hammering wooden blocks into the rock, and allowing them to absorb water. They will expand and crack the rock in the process.

[Anthony]

Heating a large rock would take a large amount of thermite, it be much more efficient to simply build a fire around it as described. Even then it'd probab;ly take an hour or two to heat up.

Thermite isn't some magical substance that is automatically ideal for any and all situations that require heat.

[grammarless]

There was a large rock under our cabin where my dad wanted to put a screen porch. He asked a neighbor, who is a retired logger, the neighbor said to drill a few holes and drop in a half stick of dynamite. Sadly my dad didn't go for that one. :( So he bought an inch carbide bit for his hammer drill, and some shims to split the rock. But he only managed to drill a one inch hole a few inches deep in an hour, almost burned out his drill. So, unless you have some sort of jack hammer, drilling a hole and filling it up with explosives is out of the question.

[jeffchem2000]

if the hole required for the charge is bigger than the biggest drill bit you have. What I have done is to drill a hole in the middle and 4-6 holes around it. Then fill the surrounding holes with det cord and blast all of them at the same time. The hole in the middle is left empty and when the cord is detonated a quite accurate circular hole is made. If this is done 3 or 4 times in the same place, you will end up with quite a deep hole in which a very big charge could be placed.

[User Name]

I have a simalir problem. well...more of a challenge actually. i have a 4 foot diameter boulder that is out in the desert where i go shooting. i have tried several times about 2 years ago (i was far less experienced with explosives) to destroy this huge rock but failed. everytime i go shooting at this spot it laughs at me so i want to take it out.

a nice lil thing about this boulder is that theres a fox hole underneath it about 1 foot deep and 10 inches wide.
(i guess the fox didnt finish his new home)
how much AN/acetone do you think it would take? there is a highway about 3 miles away so i dont want to overdoit very much (i tend to do that soemtimes) :)

[zaibatsu]

4 feet diameter? Hmmm, that's a class D4 boulder, so just uprate the standard B6 charge by about two times.

[User Name]

class D4? ok i think ill just use a 1gallon paint can full of my AN/acetone 95:5 and use a 20gram AP det.
will that work? the rock is pretty hard stone

[DBSP]

It would be better if you made yourself a ANWAX comp insted as the sensitivity of a 95-5 AN to acetone hasn't been studied yet. I've tried a AN-acetone charge once but I am very unshure wether is was a complete det, I used a shotshell of APAN as det that time.

Point is if you don't want to risk an incomplete det, try something that has been tested. An ANWAX comp with a 20g AP det is shure to work.

[Desmikes]

there was a patent about activated AN and the guy was demolishing 2cubic yards of limestone with I think 1kg ANNM or/and ANNM + xylene by simply placing the charge on top (if I remember correctly). I don't know if your rock is harder or not but given the fact that your bolder is smaller, you might wanna try 1kg charge if you don't wanna "overdoit"

[User Name]

ok thanks guys 1kg it is. but i havent a clue as to where to get nitro-methane and i dont know much about ANWAX.

[DBSP]

Search for gods sake, I've told you before, H2O2 has been discussed to death and so has NM. It's all here on this board.

If you would have bothered to search you would have found the ANWAX thread and read it, along with all the other posts on ANWAX. You would definately be able to understand and use ANWAX if you have read what has been writen on the subject. I myself have studied ANWAX quite thoroughly and others has replicated my attempts with success.

Search and you WILL most likely find what you are looking for, going back 30 days isn't enaugh since there are posts archived from more than TWO years meaning that it has most likely been discussed in the past and archived for you to find it.

[zaibatsu]

ok thanks guys 1kg it is. but i havent a clue as to where to get nitro-methane and i dont know much about ANWAX.

Username, let me remind you of another post:
yes i have read the rules and im sorry. i didnt do a search i only looked at the threads from the last 30 days. it wont happend again.

You're outta here!

[Ithacacian]

I apologize for not replying to any particular previous statement, however this seemed to be the appropriate place to put information regarding a rock blast at a coal mine I recently witnessed. Maybe this information is of no use, but I have used so much of the forum, why the hell not.
To strip mine, they:
Drill holes pneumatically ranging from approximately 9 to 11 inches some 60 feet deep. The holes are arranged between 30 and 35 feet apart, and are fired by a shock induced hollow 500 millisecond fuse which was I think 1000 m long with PETN inside, in such a way that the fuse always keeps ahead of the blast. The primary was PETN and the booster was a mix of PETN, nitroglycerine, and other recycled military explosives. There was less than a kg of booster per hole, placed centrally in the columns, each of which contained in the neighborhood of 500 kg of ANFO. The ANFO was ammonium nitrate mixed with 6% diesel, which he cited as an oxidizer and not sensitizer, and an emulsifier similar to petroleum jelly in the range of 5 to 50%, with 30% being standard and 40% completely waterproof, the primary reason for using it, as he said it didn't really add much power. I was 1000m away when the blast went off, some 30 holes with 500 kg of ANFO each. The sound was not as impressive as some relatively similar charges I have set off slightly below ground of some 1/50000th the power at approximately 10 m. However, the shockwave was very noticeable under my feet, and the blast loosened hundreds of metric tons of rock. The results were impressive. This took place in southern Indiana, USA. All of this information is readily available on the site, but I thought it might be useful to know that that is how the professionals do it as well.

[Ithacacian]

Was reading again, knew something was wrong: meant to say 5000 kg, actually probably closer to 8000

[Maniak]

A month ago, I was in some near mine. It´s nice place for experiments with rock blasting, because nobody hears the terrible noise ;) I like minerals and I´am sad when it grews from the rock and I can´t get it.... :mad:
My way: 20g of HE as a SC with hemispherical!!! liner (20mm diameter) can make 10cm penetration to the best concrete or rock.
When it doesn´t break it completely, it makes a hole for next 5-10g of HE (I think blasting gelatine with Al is good for it´s high energy and low crit. diameter).
This method is quite cheap - you need only 30g of HE and two detonators...
I want to make a few tests, so I hope it will works.

[atr]

Examine the boulder closely . In most you'll find a hairline crack somewhere . That would be the best place to drill . If there is no crack check the dimmensions and drill half way into the narrowest part . Try to drill down and in on a 45 degree angle . Any explosive equal to a 1/4 stick of 30% ditching dynamite will break it provided that the charge is centered and your drill hole is stemmed with sand , clay or mud . If it is a large boulder you'll have to repeat the process in sequentially smaller pieces . A 1/4 stick will break a 10 foot diameter granite boulder in half . If you overload it you'll get flyrock and that can be dangerous . You could pour black powder through a tube into the hole and electrically initiate it but it must be tightly stemmed . Mudcapping is another technique that will work but requires a lot of explosives depending upon the size of the boulder . Pile your explosives on top and place a 50 pound bag of sand on top of the explosives . About 10% of the force will go down and 90% will go up so mudcapping is very inefficient and with the ammount of explosives required all of your neighbours will see it , hear it and feel it . Drilling or digging a hole underneath the boulder to place the charge isn't much more efficient than mudcapping with the added problem that if you load too heavy you'll have rock and earth flying everywhere .