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a11051605
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[*] posted on 12-12-2018 at 19:41
Need advice from experienced pyro


Ill start this off by saying I am an amature chemist but I do have a healthy respect for chemicals and exactly following directions for preparation and their use. I was looking to get some input from someone with some knowledge and experience as to a proper way to set off a ANFO charge in a hard rock vein for sampling. At this point this is what I am currently thinking and would like some inputs.

Looking to do a small charge and with ANFO being a tertiary explosive I understand the need of a booster.

Primaries considered: MEKP (mixed in sawdust onsite), MEKP/AP, or MEKP/AN

Booster considered: AN/AL w/flash powder.

Main: ANFO or ANFO/AL or ANNM

Bore hole: 2ft deep by 1inch.

Method: Separate/individual (chemical) paper encased charges packed in lightly with wooden rod. And set of via electric charge in the primary.

Reasons these are being considered is ease of making, cost, and stable enough. Although the MEKP does kind of make me nervous, but from what iv seen its stable enough as a liquid for transport.

Im thinking at this point of a 1g primary setting off a 2g booster to a 4g main should fracture the rock enough to shatter it but not blow it to kingdom come.

Would really like some helpful input on this so it could be done right and most of all safe, also understand there are better chemicals out there like lead azide as a primary but those chemicals are not readily available and the preparation sounds pretty dangerous. Open to ideas on chemicals/mixes just keep in mind the "amature" at the start of this post.

[Edited on 13-12-2018 by a11051605]

[Edited on 13-12-2018 by a11051605]
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[*] posted on 12-12-2018 at 19:48


1g primary... 4g main?
Flash powder??
MEKP?

I understand that it is hard to get advice when it comes to explosives, seeing as no-one really wants to teach you this stuff. But still, you can't use a jackhammer to break the rock? :)
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[*] posted on 12-12-2018 at 21:38


Ya that's the trouble is getting some one to teach or even talk about it, which is kinda sad thats the point our world has gotten to. Any way, yes jack hammer can get rock to break, if you want to some how haul a generator up to location, run power cords, and spend the day working it. Not trying to be a smart ass btw as it would be a valid option if this was say my back yard. Unfortunately explosive is most efficient way as far as time, effort, and cost.

Also on a side note I'm also looking into ETN as a primary.
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[*] posted on 12-12-2018 at 22:56


Peroxides of any kind aren't a good idea, and in such small amounts neither is ANFO.
I don't know your level of knowledge or respect of explosives in general and I certainly don't want anyone getting hurt or killed for lack of knowledge or respect.

It's not a matter to take lightly. Missing fingers, severe hearing loss, permanent blindness and death are all a possibility, even in the fairly small amounts you're talking about.
With one slip or poorly thought out action you can instantly find your life ended or changed forever over something that doesn't matter even remotely in the grand scheme of things.

My best advice is to find another way. A sledgehammer and chisel will do the work of 5g of explosives in much less time than the preparation/setting up of an explosive charge.

If you insist on using explosives I'd recommend steering clear of peroxides and investing a bit of time in finding safer alternatives (Azides are not any better for amatuer use).
I'm happy to provide info on how to safely accomplish your task but the safe manufacture/usage of explosives is a very complex thing, and without knowing your exact plan I can't even begin to help you.
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[*] posted on 13-12-2018 at 03:27


Quote:
Also on a side note I'm also looking into ETN as a primary.

Though ETN isn't a primary, it will detonate from flame under strong confinement and its power is comparable to that of NGl...

A column of 4-6 inches ETN within your rock, with BP pressed on top for strong ignition and tightly tamped with dry soil or sand will likely split the hardest rock.

Just don't rush into it ─ some research is advised...

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[*] posted on 13-12-2018 at 04:51


Would you be able to make the diameter larger and use something like BP instead? I would bet that the extra amount of time for making the primary, booster, etc would be longer than making the hole bigger and using BP. It was used very successfully to blast through many mountain ranges (Rockies, Andes, Alps, Urals, etc) and I would suspect it would be much safer.

Also, what about making something like nitrocellulose or even NG and then using sawdust and or clay to absorb it. I seem to recall that being an effective method to safely handle it.

I still think BP might be a reasonable alternative and the easiest to make and work with.
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[*] posted on 13-12-2018 at 08:37


Actually I have thought about alot about BP due to its historic use and reasonable saftey curve. Was actually thinking of doing some control tests on it by recording time, cost, material used and result in a vein. If BP works I would use it, really only a matter of what shatters the rock with the least overhead and least difficulty. Again sense I am going for shattering rock and not big exciting explosion I think my options are flexable.

Also for people's fyi, locations are remote and involve rough roads and trails so any product needs to take small bumps from travel. Although I think padded case can help with this. Also why I was looking at MEKP in liquid form I have heard it is stable. Only problem I can see with BP is a static discharge but I think that hazard is pretty remote.

[Edited on 13-12-2018 by a11051605]
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[*] posted on 13-12-2018 at 08:43


Also would add reason I am looking at other HE other than BP to begin with is the amount carried to do a given amount of work. If it's possible I think a given small compact charge of HE vs large bag of BP would be preferable.

Hard part is figuring out a detonater material sense by there nature most are more unstable, so im open to ideas.

At this point I'm leaning toward ETN as booster over AN/AL w/flash, sense ETN sounds safer then dealing with flash.

[Edited on 13-12-2018 by a11051605]

[Edited on 13-12-2018 by a11051605]

[Edited on 13-12-2018 by a11051605]
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[*] posted on 13-12-2018 at 09:16


Also to ward off any more hammer comments I'll provide some more background info. Sample size I'm looking to take is 1/4 to 1/2 ton of rock, we arnt taking a few gram sample or else I would obviously use a hammer. Also quartz and granite rock body's are very resistent to compressive force, i.e. hammer, but are very weak to shock, i.e. HE.
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[*] posted on 13-12-2018 at 09:54


7 grams of explosive is going to scratch the rock, maybe. You need a bit more. I have no idea how much and I'm not going to guess. But make the 7 g charge as a small practice charge.

Go for ANNM, you don't need a booster, but without a primary it is safe. You could set it on fire and drop it down from a flat and nothing would happen.

Now the primary... Those are tricky, ANNM is sensitive for a small detonator so you only need a small one. But a small one will still blow your fingers off. What I used to do was making a bit of PETN (10 grams last a long time), and put it in a drinking straw, like half a cm or so.

Until here things are quite safe, now comes the primary. I used dextrinated lead azide. It sort of dries in grains and as long as you are gentle with it and avoid static electricity it is likely fine. You only need one 30 mg-ish grain to set of PETN. Wear goggles and ear protection and never hold the detonator directly.

Think long and hard before you operate, and practice with sugar or so to mimic the explosives. Practice until you are able to put together a detonator without touching it directly. Half a centimeter (half a gram to a gram of PETN) is not too bad when it explodes, as long as you wear protection and you don't touch it, and it doesn't get the chance to propel metal or thick plastic.

I made a lot of mistakes by going in without experience with real explosives, but I survived. Please don't do the same, practice with fakes, then with BP (I will explain), and only then with a real charge.

For example, I used to use the fuse from fireworks, from what we call "roman candles", 30 cm long and burns for about 30 seconds. My detonator was a coke bottle cap filled with TATP, the side facing the fuse was normal plastic band. Someone told me to use a drinking straw to protect the fuse, but forgot to mention to take it away before lighting. I put it straight up and probably a drop of burning plastic fell down in the detonator setting a 200 g ANNM charge of after only four or five seconds. Could have been a lot worse, now I was only left "shocked". With BP it would have been less bad.

After that I started filling drinking straws with KNO3/sugar and lay them horizontally. Works pretty well, no sparking and burns for a minute orso. Is your drill hole vertical or horizontal? If it is vertical consider re-drilling or electrical means to set it off.

Don't look at detonations that are covered with something, whatever it is. Make sure you are behind something, also with the 7 gram charge, you never know. I never used anything different than plastic bags and straws. Metal or thick plastic will form deadly projectiles.

With electrical means to set of the detonator always connect everything to the detonator before you put it in the main charge. And with every maneuver, be aware there is a chance the detonator goes.

Putting the detonator in the charge is the always the very very very last you do.


Edit: There is a story about someone having a bad accident while making ETN, read it. I forgot his name but someone hear probably can give you a link. I wouldn't dare to make explosives anymore, I didn't do it for at least 10 years. The consequences are just too bad in case it goes bad.

[Edited on 13-12-2018 by Tsjerk]
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[*] posted on 13-12-2018 at 11:44


No experience with rock blasting whatsoever, though some things that seem to be worth looking into:

If the explosives are used underground, use oxygen balanced or slightly over-fueled explosives and use good ventilation. Ammonium nitrate (AN) based mixtures with too little fuel leave nitrogen oxides for example. Like you mention yourself, if you have aluminium powder available, a mix of ammonium nitrate (totally dry and finely powdered), fuel oil and about 2-3% aluminium powder may be most cost effective as a booster (or simply ammonal). Not sure how dangerous the aluminium oxide smoke after the detonation would be, so maybe something to look into. If you work in a very humid environment, remember that ammonium nitrate based mixtures are very hygroscopic and under high humidity can rapidly become desensitized.

Flashpowder can detonate ammonium nitrate/aluminium mixtures, though no idea how reliable this is. It seems far preferable to have an absolutely 100% reliable firring train, than to have a more simple, though less reliable system. Why even bother with making your own detonators/boosters yourself?! if possible I would definitely use commercial detonators, safety fuse and boosters. Dealing with a misfire seems way more work and hazardous. In any case...large amounts of flashpowder are probably more dangerous to work with than really small amounts of a primary explosive as these are sensitive to friction and static as well, so flashpowder doesn't seem very advantageous.

Though if you're really set on using your own detonators,boosters etc...I'd think regarding the safety of loading the detonator, DDNP might be one of the best primaries available. DDNP is one of the least friction and static sensitive primaries available. It is pretty impact sensitive, though I'd intuitively would say friction sensitivity is most dangerous during detonator loading. (maybe other members have other ideas about this) Anyway, once picramic acid is obtained, DDNP is very easy to make. DDNP is a stable primary, is not very demanding regarding pressing conditions and has very good flame sensitivity. Used in a well reinforced compound cap (even without any base charge), 1 gram will probably detonate most things a #8 blasting cap would do.

https://www.hsa.ie/eng/Publications_and_Forms/Publications/M...

[Edited on 13-12-2018 by nitro-genes]
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[*] posted on 13-12-2018 at 13:59


I'll look ino DDNP.
Iv read quite abit about ETN and people have done some pretty stupid things in the synth and haven't reported any issues other then low yeilds, which sounds promising sense it appears to to be some what hard to get a runaway reaction.

One thing that would be nice about flash as a primary is that I could keep it binary and mix onsite, same as the MEKP idea and saw dust.

Means of firing will be electric switch saftey away, haven't decided if I will use electric match or bridge resistor. Any way should be away from boom.

Bore holes maybe horizontal or vertical, just depends on location.

When breaking rock you use smaller charges in an array to do controlled blast, not just one big blast.
Big blasts tend to throw rock airborne which is bad, you want the rock to stay put for ease of recovery and flying rocks are bad for your health.

Also of note is that ETN is oxygen rich so would probably help get more energy from ANFO? Just a thought.

[Edited on 13-12-2018 by a11051605]
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[*] posted on 13-12-2018 at 14:09


Quote:
Quote: Originally posted by a11051605  

Iv read quite abit about ETN and people have done some pretty stupid things in the synth and haven't reported any issues other then low yeilds, which sounds promising sense it appears to to be some what hard to get a runaway reaction. .

You haven't read about the guy losing both hands I was trying to warn you about (the ETN story)l
Quote: Originally posted by a11051605  

One thing that would be nice about flash as a primary is that I could keep it binary and mix onsite, same as the MEKP idea and saw dust.

Don't use peroxides. definitely not mixed with unknown crap. Pure compound are nice because they are pure. I wouldn't touch MEKP/saw dust with a ten meter pool.

Quote: Originally posted by a11051605  

Means of firing will be electric switch saftey away, haven't decided if I will use electric match or bridge resistor. Any way should be away from boom.


Don't forget to test. Did you ever test? If so, what did you test?





[Edited on 13-12-2018 by Tsjerk]
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[*] posted on 13-12-2018 at 14:25


Absolutely will be testing, just at this point trying to figure out what to synth and test lol.

You are correct as far as story of guy getting maimed, but I will say that is only one iv read about so far, and I do appreciate the heads up.

As far as MEKP and saw dust, lots of liqued HE's have used paper, saw dust, or diatomaceous earth as a soak medium to make them primed for det. Also many references to guys using MEKP with a soak medium for blasting. Note that I'm not married to the idea of MEKP I'm just pointing out.

Thank you for all your replies btw. Lots of good ideas and good inputs let keep it going.
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[*] posted on 13-12-2018 at 15:35


I think it would help if we knew what kind of rock you are drilling and blasting or at least how hard it is, size, etc. How long did it take you to drill the hole if you have already? What did you use to do it?

I don't think you need to worry so much about BP when it comes to travel and such. I doubt it will be more than a lb to fill that hole you mentioned and that is sold in gun shops in plastic containers. IDK if that is the type that is usable in this situation, I'm not talking about smokeless rifle/pistol powder, I'm talking about real black powder for muskets. It might be the easiest and cheapest option when you look at the over-all picture.

Another idea with the BP is to drill the hole, put in a fuse/blasting cap, wadding (cloth of some type) and then a plug. I would guess that you would get better results if you really sealed the hole with something like a quick drying epoxy around the plug (or even slow drying/6-24 hr if u have time) to make sure as much energy is transferred into the rock as possible.

Also, when you say "shatter" the rock, what do you mean and why? Do you need it in gravel size pieces for some reason? Or would 20-100lb chunks be small enough to move out of the way.

What is the plan with this rock and why blast it. You will get a lot better answers to your question (and alternatives) if you tell us. If it is for gold or mercury ore or something, don't worry, no one is going to come steal your find.
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[*] posted on 13-12-2018 at 17:03


Rock is for metalic ores. That are mostly quartz granite. On a hardness scale I believe quartz is an 8.
When I say shatter I mean break into smaller parts less then say 100lbs. Looking to break then process the rock in bulk sampling to determine value content of rock. Need to do a large sample and get deeper then the weathered surface face of the rock.
Was going to experiment with plugging the hole to incease pressure probably just using some slightly damp/compressed surface dirt.
The BP sold in stores is not real BP, they are a BP substatute that is more stable and most claim less powerful then real BP and go for much more money. If I was to go BP route I would be making my own.

Assuming rock contains values will move into small scale underground mining using small controlled blasts to prove the vein.
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[*] posted on 13-12-2018 at 20:39


Quote: Originally posted by a11051605  
Rock is for metalic ores. That are mostly quartz granite. On a hardness scale I believe quartz is an 8.
When I say shatter I mean break into smaller parts less then say 100lbs. Looking to break then process the rock in bulk sampling to determine value content of rock. Need to do a large sample and get deeper then the weathered surface face of the rock.
Was going to experiment with plugging the hole to incease pressure probably just using some slightly damp/compressed surface dirt.
The BP sold in stores is not real BP, they are a BP substatute that is more stable and most claim less powerful then real BP and go for much more money. If I was to go BP route I would be making my own.

Assuming rock contains values will move into small scale underground mining using small controlled blasts to prove the vein.


Well if that is the case then I think BP would be a good choice. I'd be very interested to see the difference between a blast where you use tamped dirt vs where you use something like a metal rod/bolt epoxied in place. Speaking of bolts, if you can drill a nice round hole then you might be able to use a bolt and screw it in. Use a wrench with a long extended arm/lever (like a pipe of some sort). Drill a hole through the bolt to feed the fuse through the bolt.


If you needed it in more of a gravel or small chunks like a couple lbs, then I think a HE would be more effective but for breaking rock free to get to the material below, I think BP will be a good choice b/c it gives a slow powerful explosion not like the much faster shock wave of the HE.

It would be interesting to see how the different EM's work! It sounds like a fun project!
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[*] posted on 13-12-2018 at 21:15


Ya I'm looking forward to it. At the mines iv worked at they use ANFO cause for a HE it's slow and if you watch them do an explosion the ground just kinda heaves up alittle then falls back down but all the rock is nice and broken up now. I will be posting results of diffrent tests later on with results of diffrent charges. Luckly iv managed to rope a pyrotech and a master blaster into my little adventure so that will be interesting. Pyrotech was pretty interested in ETN as he had never heard of it b4.

I'm sure BP with an epoxy bolt in place would be interesting as all that energy has to go some where.



[Edited on 14-12-2018 by a11051605]
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[*] posted on 13-12-2018 at 21:32


Its good to see this thread have healthy discussion, and for OP to take things slowly. Not to de-rail meaningful discussion but:
Quote: Originally posted by a11051605  

Booster considered: AN/AL w/flash powder.

Is this a thing people do? Where has this idea come from, it seems very strange. I feel flash powder has no place in an explosive train, but is a thing that amateurs have been known to do??

[Edited on 14-12-2018 by Tdep]
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[*] posted on 14-12-2018 at 00:36


Quote: Originally posted by a11051605  
Luckly iv managed to rope a pyrotech and a master blaster into my little adventure so that will be interesting. Pyrotech was pretty interested in ETN as he had never heard of it b4.


[Edited on 14-12-2018 by a11051605]


In that case you should be able to source and use a reliable commerical initiation device/setup, right? That would take 99% of the danger factor off the rock blasting operation.
It is the primary initiating part of the explosive train that hides the most dangers and causes of failure, especially in an amateur setting. In light of that I would steer off from any improvised solutions for that part (especially what concerns peroxides).
Should one still out of scientific curiosity choose to go all the way from scratch, then for reliability sake I would also not suggest to use combinations that rely upon DDT (deflagration to detonation transistion) effect.....from practical perspective these solutions tend to be very demanding in terms of preparation procedure and still prone to failure. And the result is that one has to deal with a failed blasting charge...a very dangerous and unpleasant activity.

Perhaps the best bet would be the BP route, it is relatively safe simple and functional. With no HE related issues involved.




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[*] posted on 14-12-2018 at 04:37


Great to see that you have thought about this a lot.

I only see good advice in the comments above. Your idea of tamping the charge with epoxy is excellent. Water tamping also works quite well.

A couple of things come to mind:
- I've seen people break limestone with a drill, a .22 long, a metal rod and gloves.
- BP is very cost effective
- Tried initiating ETN with thermite: no joy.
- You have considered MEKP (bad idea)
- You have considered ETN (great but needs primary)
- I am not sure the diameter of your hole is enough for AN based composition.

But...
If you considered MEKP you shouldnt be afraid of nitroglycerine. If you have considered ETN you have the precursors for nitroglycerine and nitrocellulose.
You can make your own gelignite, buy commercial firecrackers and forget about the primary / detonator dilemna.

You know your rock, obviously have made some research and sound safer than many.
Let us know how it goes ;)
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[*] posted on 14-12-2018 at 06:19


As I understand it and please correct me if I am wrong but isn't synthesis of NG very risky? From what little I have reaserched about NG I have heard a 2 degree change in temp can trigger detonation? Haven't reaserched NG much cause of its bad rep.

As to the AN/AL w/flash ya it's a thing, makes the AN/AL more sensative in that when grouped as a charge the flash helps kick things off. Not really considering it much now.

With the other pro's involved I do now have access to better blasting gear/tools but still interested in making own charge for scientific and self reliance. Will be nice to have experianced supervision though.

As every one has pointed out the biggest hang up is the primary.
Like the good ideas and discussion.
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[*] posted on 14-12-2018 at 07:11


Hmm been reading about NG and kinda confusing cause so much conflicting info out there. Some claim it's super hazardous and will blow up with one wrong look, and others claim to have synth'ed it and as long as you keep your temps in check during synth and treat product with respect that it is actually harder to det then alot of the peroxide based explosives. Any thoughts or experiance any one?
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[*] posted on 14-12-2018 at 09:14


As a side benefit I would think that if you use BP you could get away with cannon fuse or even an E-match type thing (nichrome or a bridge wire). If you are worried about initiating he charge you could add some of that flash powder you discussed in a small charge of maybe 1/4 - 1/2 gram (been a LONG time since I've seen FP so IDK the volume anymore...). I think normal fuse should be fine for either though.
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[*] posted on 14-12-2018 at 10:14


Quote: Originally posted by RogueRose  
As a side benefit I would think that if you use BP you could get away with cannon fuse or even an E-match type thing (nichrome or a bridge wire). If you are worried about initiating he charge you could add some of that flash powder you discussed in a small charge of maybe 1/4 - 1/2 gram (been a LONG time since I've seen FP so IDK the volume anymore...). I think normal fuse should be fine for either though.


Blackpowder will ignite with any source of heat without problems. No need for flash powder.
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