Using non explosive sensitizer(s) (no NG, PETN, nitromethane, TATP etc.) and AN, what is the minimum charge Dia. that can be used with reliable
propagation? Assuming good tamping and containment, as in a bore hole-
By including crystallization modifiers used with melts rapidly flash cooled and granulated in the anhydrous condition, critical diameter and cap
sensitivity below 1/2 inch has been reported. See GB1014071, page 13 Example 2, describes a melt composition of 79% NH4NO3, 20% urea, 1%
methylcellulose, granulated on cooling and packed was cap sensitive at 3/8" in copper tubes. What would be the phase stability and storability for
such a composition is unreported, but it is probably poor. Using fuels which form adducts like hexamine or glycine can help keep the critical
diameter low while keeping the density up, and aluminum flake can help also. Solid or plastic emulsions would probably have the best storability and
reliability. There are an assortment of patent and proprietary compositions where various minor ingredients have been used as refinements.
Some of them are cap sensitive at 2" or even less. The crystal size and phase of the NH4NO3 is a definitive factor.
Very specific crystalline forms of pure NH4NO3 (for the interval they last) are cap sensitve, without any sensitizer whatsoever. But this is a
laboratory curiosity without some way to stabilize the NH4NO3 against its usual behavior of changing crystalline form with temperature and humidity
changes during ordinary storage.
[Edited on 9-12-2010 by Rosco Bodine]Bert - 9-12-2010 at 10:57
I was thinking in terms of diameters workable in practical applications rather than laboratory curiosities- But lab curios are instructive...Rosco Bodine - 9-12-2010 at 12:09
IIRC one of the better simple 2 component oxidizer - fuel systems was acetylenedicarboxylic acid with ammonium nitrate, and I think it was a melt cast
that was cap sensitive
having sufficient energy and velocity to make it useful as a booster for blasting agents. Emulsions are a lot cheaper though. There have been some
foamed melt casts using urea. Some of these mixtures may actually react chemically to form in situ separate energetic compounds which sensitize the
mixtures.
The acetylenedicarboxylic acid sensitized oxidizer actually used a mixture of different oxidizers, probably for lowering the melting point but likely
also for phase stabilizing the NH4NO3 component of the mixture. See US4689096 .
[Edited on 9-12-2010 by Rosco Bodine]grndpndr - 9-12-2010 at 15:36
Im assuming, maybe wrongly your referring to ANFO and the smallest diam borehole practicable.
I did a quick search google (your job) and came up with at least 20 related pages of info concerning anfo and borehole diameter ,density etc.FWIW one
of the sources reccomended a 3in min borehole w/anfo another 5ml larger at 80mm.I quit after seeing 20pages of related material free for the effort of
reading it.Anfo must be one of the most thoroughly researched explosives out there just take advantage off the published literatureBert - 14-12-2010 at 09:10
grndpndr, wouldn't it have been quicker to type UTFSE? (I did, filtering that
mass of info on an iPhone in the wilderness wasn't going well)
3" isn't going to do it. 1/2" to 1" Dia. is more useful. The link to ammonals and Aluminim containing emulsions provided by mabuse_ covers the range
of diameters I am interested in. More specific application information will probably get this thread shut down.
I'm curious also as to how those water emulsions behave at low temperatures. Temperatures are running below zero F here lately.
(edit) looks like they don't work at low temps without additional sensitizers such as amine nitrates.
[Edited on 14-12-2010 by Bert]grndpndr - 15-12-2010 at 11:59
Why did you withold pertinent information!1.5 in borehole?!That
narrows down the AN sensitizers some wouldnt you say
And why Didnt/dont? you UTFSE!
[Edited on 15-12-2010 by grndpndr]
[Edited on 15-12-2010 by grndpndr]
[Edited on 15-12-2010 by grndpndr]Bert - 22-1-2011 at 14:08
A test shows that Tannerite will propagate in a lightly confined 1/2" Dia. column- This is the results of about 6 Oz. loosely loaded in a 4 foot
length of 1/2" CPVC plastic water pipe. witness plate is 1/2" OSB board. This is a test for a movie special effect shot.
Heavy grain det cord is more appropriate and dependable for such effects- Any packing or settling of the charge results in a failure to propagate.
Interesting AN-CN Double Salt mixtures
Rosco Bodine - 11-9-2014 at 06:23
Here is another method of producing low critical diameter and cap sensitivity even for not fully anhydrous AN compositions. See US4084995 attached
Blaster Training Manual / one continuous url http://cdn.preterhuman.net/texts/terrorism_and_pyrotechnics/explosives/Demolition_Blasting_Sabotage/Blasters%20Training%20Manual%20(Farmers,%20Rancher
s,%20Prospectors%20&%20Engineers)%20By%20R%20K%20House.pdf
From bottom pdf page 103 , or just search " less than "
" ANFO mixtures are generally suitable only for heavy loadings in large diameter
shotholes, because their explosive reactions become more efficient as the
column diameter increases and the quantity of the ANFO is increased. Blasting
agents are seldom used in shotholes less than 4 inches in diameter, and are
not reliable or efficient in small shots."
Rosco Bodine has posted for you the lower bleeding edge of investigation into ' minimal ' diameter.
I can suggest experimentation using organic acids as these sensitize AN more than aliphatic or
carbohydrate fuels. Try acetic , and carboxylic compounds.
On my own I have been musing at in situo chemistry as done with Astrolytes.
NH4NO3 + N2H4 => N2H4•HNO3 + NH3
Add mixing Sodium Nitrite to a saturated water solution of AN yields Ammonium Nitrite
NH4NO3 + NaNO2 => NH4NO2 + NaNO3
NaNO2 - Solubility in Water: 46% @ 20 ºC
NH4NO3 - Solubility is twice as much higher
I can find no literature on this , just this related patent US2285843
Likely because it's unstable and quickly hydrolyses. Non aqueous solvation does not appear fruitful since
the amounts dissolved are low.
NH4NO3 - 100g Isopropanol or Methanol dissolve 17g @ 20 ºC
NaNO3 - 100g Methanol dissolves 16.7g @ 30 ºC
NaNO2 - 100g Methanol dissolves 4.4 g @ 25 ºC
NaNO2 - 100g Ethylene Glycol dissolves 16.7 g @ 25 ºC
[Edited on 11-9-2014 by franklyn]Bert - 11-9-2014 at 14:16
Here is another method of producing low critical diameter and cap sensitivity even for not fully anhydrous AN compositions. See US4084995 attached
Curious to know of any low temperature related sensitivity decrease to these mixtures, particularly those without nitrotoluenes- They don't specify
the testing conditions... Even Tannerite seems to get a bit sluggish at -10 F. Several of the other mixtures I looked at when this was a new thread
were not all weather performers either.
AN diameter
Laboratory of Liptakov - 12-9-2014 at 12:43
I can do tests in diameter 12.5 mm. (Patent US3247033 A) describes VoD 3100 m / s in 0,5 inch. This composition is tested on average 19.5 mm. A work
from No.8. 1 meter long plastic tube? No problem. The mixture must be dry. The density of 1 to 1.2 g / cc. Wooden board? How thick? Or any other
source material?.....
LL
(I did, filtering that
mass of info on an iPhone in the wilderness wasn't going well)
