Emulsion Explosives

[MrMagnum]

Did you ever try to make an emulsion explosive?

You could do it this way:

Take 30g of mineral oil (i.e. diesel oil) and 70g of water. Heat the water up to 80°C and dissolve 350g ammonium nitrate in it. Then take an emulsifier, which is made for water-in-oil-emulsions, for example eucerit. You can buy it in a pharmacy. Dissolve it in mineral oil. Now mix both solutions with an electrical stirrer. Mix them very well! After that you have an emulsion. But this emulsion is not yet capable of detonation. You need to decrease the density. Take micro balloons and put them into the emulsion. The emulsion becomes cap sensitive, when the density is lower than 1,15g/cm3. The emulsion is booster sensitive between 1,15-1,20g/cm3. You can also use chemical gassing instead of micro balloons.

Use this recipe only for legal purposes.

[JV44]

You mention emulsions under 1.15 beeing cap sensitive. Have you ever done experiments on the reliability of that? I wonder because whenever I use emulsions in that density range in commercial rock blasting, people make me use booster charges. They don't trust the cap sensitivity of any emulsion explosive.
Btw, I was surprised by the power of modern emulsions when I started using them. They have mostly replaced the expensive gelatin explosives in my work.

[MrMagnum]

yes, they are definitely cap sensitive. take nobelit 310 as an example.

emulsion explosives have many advantages:

1. low cost
2. easy to prepare. without any danger!!
3. high detonation velocity (4.500 - 5.500 m/s) even without any confinement
4. low toxicity
5. water proof
6. good strength
7. very SAFE to handle

[cutefix]

4500-5500 Vdet? With just ammonium nitrate,carbonaceous and or metallic fuel and water plus mciroballons and stabilizer?
I doubt it. Knowing the density is not high If you add a self explosive oxidizer like TNT into the mixture and the like, may be that is possible but without it is unlikely to reach such explosion speed .
It would be interesting if you can present some data related to your trials that you were able to reach such detonation speed.

[0EZ0]

I would have though that most commercial emulsions with high detonation velocities contain nitro glycols. I too see no reason why the above mentioned emulsion would have such a high detonation velocity without some other added compound.

In recent years nitro glycols have been replacing nitroglycerine in commercial explosives due to the lower cost. I'm sure I have seen some emulsions that contain these glycols. Nobelit could contain a similiar mix.

[JV44]

I don't know the ingredients of Nobelit, but I definitely don't get a headache from it. I am very sensitive to nitroglycerin and nitroglycol, I get terrible headaches from cutting even less than a hundred charges containing blasting oils. With Nobelit I've never had any problems. In a couple of weeks I'll be at Orica's German production plant, I can ask them what Nobelit consists of.
I do know they claim a det velocity of 4500m/s for the small diameter sticks(25mm).

[MrMagnum]

the detonation velocity is indeed that high. Even without the addition of high explosives!! the reason is that the ammonium nitrate and the fuel are mixed in an emulsion. very tiny ammonium nitrate bubbles are surrounded by a thin fuel layer. this mixture has a much better contact between fuel and oxidizer than ordinary anfo.

look up the data sheets of emulsion explosive manufacturers, i.e. www.orica.de or www.ael.co.za ! there are even more maufacturers. you find them via www.metacrawler.com or another search engine.

[cutefix]

If we look at emulsion explosive as it is we will never able to get the same power as the nitroglycerine type items such as straight and good gelatine dynamites.( in the realm of above 5000 m/s). Unless we introduce into the emulsion such potent explosives as RDX,PETN and TNT. Into such mixtures but that will make the product more prohibitive to improvise knowing the cost and the risk of synthesizing such substances.

BTW, one of these explosive companies still produce emulsion explosives with just a moderate Vdet of just slightly above 4000 m/s. and the explosive density is just in the realm of 1.2 g/ cu.cm
But anyway….
Due to the nature of this post ( which is interesting )as it could be an alternative way to make moderately powered explosives without the need of watched chemicals such as ammonium nitrate and well known explosives.
I made some formula search in my friends file and indeed the explosives technologists had come with an invention which is more of a modification of the known art in emulsion explosives.
Maybe this is the way how these companies make explosives without the need for explosive oxidizers.
But they do not use ammonium nitrate anymore but perchlorates
One formulation that came to my interest is this copied from:US patent 5,880,399 formulation
“Cast Explosive with Microballons”
It looks very interesting…..maybe this what you mean magnum.

Knowing that cast explosives are high in density than normal emulsion type explosives. It could be predicted to give more power then;
Have a look at this composition guys. I just cannot check the source as the server I am using seems not able to contact USPTO. Maybe somebody could explain how this was made and see the difference from normal emulsion explosive
NaClO4 70.16
Diethylen glycol 24.62
Water 3.98
Xanthan Gum 0.04
Glass/plastic
microballoons 1.20
Oxygen Balance -0.51
Density (g/cc) 1.60
Results of detonation at
Charge diameters
Detonation with #8 blasting cap
In (km/sec)
75 mm 6.3
63 mm 6.3
50 mm 6.0
38 mm 5.9
32 mm 5.7
22 mm 5.4
19 mm 5.0
12 mm 4.2
Indeed a very interesting development in the commercial explosive field but I still had to see the actual results if its really works as claimed.

I presume its easier to buy sodium perchlorate than ammonium nitrate now as it not subject to explosive tagging and being on the watch lists as this AN is the most widely used substance in improvised explosives recently.
I just do not know the price difference between Ammonium nitrate and sodium perchlorate.

Diethylene glycol is not a watched chemical either.
- it used in antifreeze formulation,textile softener,humectant for tobacco.bookbinding, solvent cosmetics etc.

Xanthan gum is easy to procure as well as with the microballons.
Maybe this cast explosive is another toy play with the roguesci folks?

[MrMagnum]

hi cutefix, you're writing about a slurry explosive. the composition does not look like an emulsion explosive.

i visited the plant of orica in würgendorf/germany. therefore i'm dead sure that they don't put high order explosives into the emulsions. high order explosives would decrease the advantages of emulsion explosives: low toxicity and safe handling!

[cutefix]

Magnum a slurry explosive IIRC does not have the same density as the cast explosive.
I agree that these so called nitrated organic explosives are usually toxic.but many of the related nitrocompounds such as monomethylamine nitrate was used a sensitizer.
But the main reason that the commercial explosive manufacturers do not add these powerful explosives is it add to the expense .
On the other hand
We can safely say that slurries are just comparable with emulsions...they are more likely to contain powerful explosives previously/
But commerical explosive technology is evolving in the same line as military explosives.

[MrMagnum]

I agree with you concerning slurry explosives. But emulsions do not contain high order explosives. On the other hand: it is possible to add them to emulsions. There is just no need for it as emulsions fulfill any requirements for commercial blasting.

[cutefix]

I think we can call emulsion explosives as water gel type explosives as emulsion is usually a bound mixture of the aqueous and oil phase as facilitated by surfactants.
The simplest emulsion explosive is water soluiton of oxidizer ( a combination of ammonium nitrate and alkali metal perchlorates) which is fueled with liquid fiuels and even fine particulate metals such as aluminum).
From that there were many variants that evolved.
IIRc when I looked at the commercial fomulation of modern industrial explosives I can see still tell tale signs of the presence of these so called demiliitarized explosives.
It is less common now than it was decades back.
It is feasible to add such materials as particulate dispersion in the same line as flaked aluminum was added in those materials.
And previously there had been some actual formulation that indeed contain such powerful explosives. That was because of military surplus of recycled explosives or in the principles of "turning guns to plowshares."
I had seen russian formulation containing HMX, RDX, TNT and PETN added as explosive enhancing ingredient in such systems.
During the end of the cold war even Russia dimillitarized its explosive booster in nuclear warheads ( during the agreement to cut down on nuclear weapons )by adding to commercial explosive formulation.
Meanwhile the radioactive material was stored elsewhere or reconverted to fuel rods for nuclear reactors.

Indeed commerical blasting does not need the explosion speed that is highly desirable in military application
What you need is just enough energy to loosen up the rock for easier removal by loaders and tractors. Then the low speed explosives that is common with slurries in the range of 3000-4000 m/s is the norm.
But you still need a little bit of fast exp[losives for boosters such used when applying ANFO type formulation and you can still see pentolite based boosters and even some RDX bases as well. Many emulsione explosives are sufficiently detonated by the common #8 blasting cap.
But for reliability there is the need of such powerful explosive the initiate the main charge.
In fact in some underground/underwater blasting operation the use of such powerful boosters is common place.

[JV44]

In Germany slurries aren't used in rock blasting any more, and I doubt they are at all avaliable. Slurries are by far too expensive.
I checked back with the folks at Orica, they said that 99% of all commercially used emulsions contain no explosives at all. If they are activated by chemical gassing at the blasting site, they can even be transportet without classification as an explosive.
They also told me to try cap sensitive emulsion explosives without booster charges for rebarred concrete blasting. Apparently, they can fully replace gelatin explosive even for that kind of work. If those promises hold, I'd be very glad because I really have trouble working with gelatin explosives.

[MrMagnum]

JV44 ist right.

Water gel explosives and emulsion explosives are not the same. They are totally different explosives. We talk about emulsions. They do not contain any high order explosives. They are just made the way I described above.

[aikon]

In Austria the company "Dynamit Nobel Wien" produces three diffrent emulsion explosives:

1. Slurry with addition of hydrated saline solution. These slurries are used in deep bore hole blasting and the holes must have a minimum of 80mm.

2. Slurry with the addition of metal powders (aluminium). "Lawinit 100" an explosive for triggering potential avalanches is one of that sort. This slurry is cap sensitive.

3. Emulsive slurries: The are based on a water-oil emulsion and are sensitized by the addition of organic and anorganic microparticels or rather by adding tiny oxygen bubbles. "Lambrex 1" for example is fifty times safer to handle than an explosive containing nitroglycol or nitroglycerin.

[JV44]

Interesting that most of you associate emulsion explosives with slurries. The stuff I get to work with most of the time is a rather firm substance and can be cut with a knife, just like gelatin explosives. It comes paper wrapped for the smaller sticks and in plastic foil for larger diameters.
In my region, liquid emulsions are used only for very deep holes (deeper than 10 or 12 meters) or for rock blasting with very large numbers of holes, total charges of 10 metric tons or more. In these cases, Orica sends a loading vehicle and the emulsion is sensitized while loading. They basically have a monopoly on this kind of blasting and have put quite a few colleagues out of business.

[aikon]

...Orica sends a loading vehicle and the emulsion is sensitized while loading...

This method is used at the "Erzberg" in styria.
The other emulsion explosives are wrapped in plastic and paper and can be cut with a knife, you're right.

[cutefix]

JV44 ist right.

Water gel explosives and emulsion explosives are not the same. They are totally different explosives. We talk about emulsions. They do not contain any high order explosives. They are just made the way I described above.

They are both emulsions but of different cosistency , density and formulation.. Slurries are usualy loose and pumpable.
Water gel type are usually firm like gelatin dynamites( can be cut with knife) but without its disadvantage of the latter.
Nowadays most of the so called water gel explosives are inert looking compositions but have a moderate power and usually cap sensitive.

[MrMagnum]

emulsions are a mixture of water in oil (W/O) or oil in water (O/W). emulsion explosives are W/O-emulsions. they contain an emulsifier to achieve the stability of the mixture. slurries (water gels) are just solutions of oxidizers and fuels in water. they do not contain any emulsifiers. this is why both explosives have different names. the explosives industry distinguishes between water gels and emulsions. look up their internet pages!

let's talk about emulsions. slurries are not up to date anymore.

[cutefix]

Whether its updated or not the major ingredients components remains similar. It is jus the manner of preparation that differ but the explosive performance also remains virtually the same.
I do not see the difference between the explosive power whether the emulsion explosives and water gel are highly emulsified or not; as well as whether its W/O or O/W type or not.
The previous emulsion type explosives are usually emulsified by the addition of salt crosslinker and vegetable gums as stabilizers.
Indeed the latest version of emulsion explosives are using the microemulsion technology to attain a closer contact between fuel and oxidizer and are more stable than its predecessors( better shelf life and less detonation failure). That is with the help of emulsfiying agent such for example , sorbitan monooleate
Nevertheless the explosive performance is not significantly affected nor modified
Whatever the surface active phenomena they are applying in such composition ,they still need the microvoids that microballons can provide as the initiating locus for the detonation.Or in short as sensitizer
Where as those explosives that contain powerful nitro-explosives that are demilitarized can be initiated usually without the need of such micro void particles.But there existence now is limited as it was not widespreadly applied in the industry knowing the very high cost of such powerful explosives as sensitizers and as well as the concern that if detonation failure in blast holes exist the explosives component will contaminate the environment.

BTW I had found some reference of these application of demilitarized energetic materials to commercial explosives which are was not given much publicity during it initial application decades back.But the bulk of information did not include classified data that I was aware of previously.
It is obvious here that they are applying the nitrocompounds present in propellants such as nitrocellulose, nitroglycerine, etc.
http://www.neutrino.co.jp/abi_naii/0-7923-6698-0.PDF
http://www.isbn.nu/toc/0792366980

[MrMagnum]

let me tell u the difference between slurries and emulsions: emulsions reach the same strength and vod of slurries without (!) any high order explosives!

[JV44]

MrMagnum,
do you know if the detonation velocity of emulsion explosives can somehow be kept under 2500m/s? In June I will be doing several large and rather thin metal platings which are difficult to do with the special ANFO we normally use. It would be interesting to see if emulsions could be used, maybe they could even be loaded in liquid form?

[Bert]

In June I will be doing several large and rather thin metal platings which are difficult to do with the special ANFO we normally use

Could you describe your process? Explosive forming? Explosive bonding???

[JV44]

I was talking about explosion cladding.Two plates of metal are held parallel at a distance from each other and an explosive is detonated on the surface of the upper plate, which is then accellerated at the other plate. You can reach an extremely strong bond between materials that cannot be bonded by any other means. For example, it is easily possible to bond a one-inch layer of titanium to a steel surface of more than twelve square meters at a time.
It is necessary to accellerate the upper plate to about 80m/s or more to achieve a reliable cladding. On the other hand, if the explosive is too agressive, having a det. velocity much over 2500m/s, you will damage the metal. The plates get terribly distortet anyway, and need to be straightened in huge presses. This process dates back to a Dupont patent from the 1960's and is quite common in Germany, but I believe even more so in the USA. Many chemical reaction vessels oder power plant parts contain explosion clad materials.
Another example would be armored steel. Two weeks ago I did some very heavy cladding that will be used in armoured BMWs. In every shot, two 3x4m large sheets of different kinds of armor steel, one tougher, one harder, were bonded together to a combined thickness of over 40mm. That sheet is then rolled to 7 or 8mm thickness. For that kind of work, about a ton of ANFO, regulated to a VoD of 2500m/s, is used. Btw, under these circumstances, the cap sensitive, powdered ANFO detonates easily without confinement. It is only boostered with very little powdered RDX for an increase in reliability.
In June, I will do claddings with a total thickness of about 2mm. Then, the powdered ANFO really is a bitch to work with, although it does work. I was just wondering whether emulsions could give me more reliable results, if there was a way of keeping the VoD down.

[Bert]

I was talking about explosion cladding.Two plates of metal are held parallel at a distance from each other and an explosive is detonated on the surface of the upper plate, which is then accellerated at the other plate.
I've got some nice kitchen pans made with this technology, 3 layers bonded: Stainless/Aluminum/different stainless Didn't know it was done on such large scale, thanks for the description.

[0EZ0]

Ah yes, the interesting world on the industrial application of explosives. And you just thought explosives were used for destructive purposes ;). It's quite interesting to see that you can harness the power in something so destructive for creating an end product that isn't blown to bits. It would be a good topic to discuss if someone wants to start a new topic.

There are really many different process for cladding metals to a substrate. Without waffling on, the below links contain some information regarding the different techniques and processes. Google it up if you need some more info.

A few links:

http://www.pcth.com/BondedApplications.asp

http://www.metalwebnews.com/howto/explosive-welding/explosive-welding.html

http://www.exploform.com/old/technieken/zexplosietechnieken.htm

As to whether you would be able to use emulsions in explosive cladding operations all depends on what materials you wish to bond. Thickness and strength of the cladding material is really what governs what explosives you can use. If you are wishing to layer the cladding material with an explosive that will give a uniform end product, I would suggest something castable or a slurry type composition that would allow itself to settle giving the best consistency. Varying densities can disrupt the propagation of the wave front and give some weak spots or imperfections in the end product even though it may not be totally visible other than serious distortion. The distortion aparrent after firing can indeed tell you alot in how uniform the detonation was. Whether these defects effect the final product after processing to any substantial degree I do not know.

Do you or your company use X-rays to determine the quality of the weld at all? Some companies that manufacture to stringent standards for exceptional applications sometimes do to determine whether it is appropriate for it's end use or not. If that sort of equipment is available, It may be of some use to test a few different methods/explosives to determine a quality controlled process that gives the best and most reliable results.

[cutefix]

let me tell u the difference between slurries and emulsions: emulsions reach the same strength and vod of slurries without (!) any high order explosives!

You are generalizing things based on limited ideas and experience..... :)

[MrMagnum]

cutefix, did you ever shoot slurries, water gels or emulsions?

[cutefix]

previously yes......and detonated a range of other explosives that you never had the opportunity ( or even dreamed ) to handle or use......

[JV44]

Do you or your company use X-rays to determine the quality of the weld at all? Some companies that manufacture to stringent standards for exceptional applications sometimes do to determine whether it is appropriate for it's end use or not. If that sort of equipment is available, It may be of some use to test a few different methods/explosives to determine a quality controlled process that gives the best and most reliable results.

I have nothing to do with the metallurgy at all, but I know the testing procedures. Using x-ray doesn't really make sense, as you cannot clearly distinguish a failed bond. The company I work for uses ultrasound on every cladded sheet, you can easily find any zones with irregular bonding. Additionally, mechanical tests are made with strips out of every single workpiece. It es extremely rare that a cladding fails, less than 1% of the shots. We mostly work with expensive, hard to get materials and cannot afford weeks or months of delay because of a single bad workpiece. If for example a verly large titanium cladding fails, it would take months to get replacement material.
So, as you can see, it is easily possible to get uniform results even with powdered ANFO. Only in very thin layers it gets difficult. Btw, you will always have some distortion in your workpiece, no matter how uniform the detonation. With thin workpieces, deformation can ve very severe, with the ends of the sheets touching. The workpiece lies on a sandbed and will never stay straight. Some shots, like the armored steel I mentioned, are done with a 45mm thick steel plate between the sand and the workpiece. Now even that plate looks like a potato chip after the shot.

[MrMagnum]

yes, cutefix, i'm just dreaming about explosives. i do not use any explosives, do not work in the explosives industry and do not know anything about emulsions.

[0EZ0]

Using x-ray doesn't really make sense, as you cannot clearly distinguish a failed bond. The company I work for uses ultrasound on every cladded sheet, you can easily find any zones with irregular bonding.

That does not surprise me. I must have made the incorrect assumption that the scanning process was X-Ray based and not Ultrasound based while talking about it with an associate. Come to think of it, yes Ultrasound would be a much more effective means of finding imperfections.

As with any processes utilizing thick cladding material you will always get a large amount of deformation due to a combination of the large amount of explosive used, the inconsistency of the surface and shape of the substrate as the shockwave travels to the the edges causing the "curling like a potato chip" effect.

You should get little or no deformation of the main substrate when the cladding material is thin (< 2mm) and the sustrate is thick steel. Although with the process I am aware of, the explosive backing is of high velocity and is not all that thick itself. Do you know what process is used for producing titanium skinned steel? Something similiar?

[JV44]

Do you know what process is used for producing titanium skinned steel? Something

Titanium on steel is actually the largest part of business for the German explosion cladding industry. It is done just as mentioned before, a steel plate on a sandbed, a titanium plate held at a distance (several mm up to more than one inch depending on material thickness) and a layer of powdered ANFO on top. If you let the titanium overlap the steel plate, you can get a flawless bond to the very edge of the steel plate. The overlap of Ti simply shears of.
In the process that you use, what kind of explosives are used? Do you use explosive sheets, and if so, what's the VoD? In Germany, sheets of a fairly fast explosive are used for surface hardening steel, I have never seen it done though.
In explosion cladding, we have to be extremely cautious about the VoD, if it gets too high it will completely wreck the surface. The cladding material actually has to flow from its original position to the substrate, as the detonation front travels from end to end, without being ripped to pieces. Sorry I cannot really explain this, for me it's just another blasting job. The company gives very explicit parameters for every shot. That really makes it an easy job, no calculations that I am responsible for, as opposed to demolition or rock blasting.

[0EZ0]

It's interesting that you use powdered ANFO as the explosive of choice for your cladding. I guess that from a finacial standpoint it is the cheapest to use and you are obviously getting successful results with it. In my mind there are probably much better alternatives performance-wise but you probably can't beat standard ANFO formulations for the price.

Given that some metals can be brittle when subjected to severe high frequency shock it also makes sense to use a low velocity explosive with heaps of gaseous detonation products as ANFO. Thanks for providing the details of your procedure, it fills a few gaps in what I know.

My interest in these sorts of areas is really only out of personal curiosity. What little I do know is from either literature or conversations with people who are in the engineering business or similiar. I only can tell you what I think from my understanding of energetics as it applies to these sorts of conditions. Explosive cladding is just one of the many applications of energetic materials that I hold an interest in. I personally do not have the experience in the field that you yourself posess.

I am familiar with the use of high velocity explosives for surface hardening of metals. From what I understand of it a sheet type explosive (presumeably a type of PBX) is affixed either with some or no standoff distance, to the metal and fired. The shockwave produced compacts the metal cystals local to the charge placement into a much more dense and hard form. Basically uses a different technique to get similiar results to annealing through a heating and cooling process. For that yes it would make perfect sense to use a very high velocity explosive in order to achieve the maximum amount of disruption due to the higher fequency which changes the crystal stucture of the metal. The same reason why low velocity and thus low frequency explosives are used in earth moving as opposed to high velocity explosives which are not as effective.

If you are looking for more information on the specifics of the processes used in the Explosive cladding industry and how it could be improved, then I'm sure others here can also offer their advice and knowledge. My knowledge only goes so far. I'm happy to try and answer any questions of course. However I can't guarantee accuracy.

It's interesting you say that you are not involved with the technical side of thigs with your cladding business. I assume that you have some sorts of qualifications in the broader explosives industry and are only contracted by certain companies without the personnel and equipment to complete the given job? Sounds a rather interesting career:). Of course I don't expect you to reveal that sort of information if it unsettles you. I'm just curious.

[JV44]

The shockwave produced compacts the metal cystals local to the charge placement into a much more dense and hard form. Basically uses a different technique to get similiar results to annealing through a heating and cooling process.

This isn't entirely correct, hardening by heat treatment uses a very different mechanism. Explosion hardening uses a similar hardening mechanism as is used in cold forming.
The explosive cladding companies have their own blasting personell, but their capacities are limited. If they need to, they can outsource the actual blasting and just prepare the workpieces. This is where you need the technical expertise, loading and shooting the explosives is very straightforward.

[MrMagnum]

Yesterday I shot an emulsion load. The main charge was Nobelit 100. I used Nobelit 310 as a booster. It was an interesting shot, because the booster explosive was an emulsion as well: Nobelit 310 is cap sensitive. The load was about 1 kg an standing on a 1cm steel plate which is perforated now...