Zinc
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Ammonium dichromate
I have heared that ammonium dichromate can detonate. Is that true? If yes could it be detonated with out a boster (just with a detonator) and what is
the velocity of detonation?
Also could be used as a replacement for ammonium nitrate in ANFO and ANNM?
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DeAdFX
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Ammonium dichromate has zero ob so it cannot replace AN in ANFO. It can be used with Nitromethane but only becausse NM has its on Oxygen. I don't
think you would gain much by using Ammonium Dichromate with nm though....
[Edited on 14-10-2006 by DeAdFX]
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Nitrojet
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Yes! actually Ammonium dichromate is a detonable explosive. However, like ammonium nitrate it needs a strong primer for effective detonation. When
initiated with 10gr Picric Acid, it only partially detonates, but strong charges of PETN can effectively prime the explosive with complete propagation
of the detonation wave through the column of the explosive. Confinement also plays a crucial role in complete detonation of Ammonium Dichromate. due
to Zero oxygene balance no fuel additive can be introduced into the compound thus making a class of explosives like ANFO based on this material.
Although addition of small amounts of magnesium powder to Ammonium Dichromate can transmute it into an explosive exceptionally serviceable in Pipe
bombs!! upon contact with flame it burns very fiercly which is absolutely different from the smouldering-type reaction of the salt itself resembling a
volcanic eruption. Also addition of Mg to (NH4)2Cr2O7 can greatly facilitate the ease and completeness of detonation. Hence, a binary mixture of
Ammonium Dichromate/Mg with 80/20 Wt. ratio, can be effectively detonated with 15gr PETN as a booster charge. Regarding Explosive Performance,Ammonium
dichromate has no special superiority over Ammonium Nitrate. it is of much higher cost and also labeled as Mutagenic and Carcinogenic! So You can
easily ignore it in face of the much powerful and yet much cheaper NH4NO3!
Ammonium Trichromate (NH4)3Cr3O10, which can be easily prepared by treating Ammonium Dichromate with Nitric Acid ( 55%) possesses more interesting
properties.
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Zinc
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| Quote: | Originally posted by Nitrojet
Yes! actually Ammonium dichromate is a detonable explosive. Although addition of small amounts of magnesium powder to Ammonium Dichromate can
transmute it into an explosive exceptionally serviceable in Pipe bombs!! upon contact with flame it burns very fiercly which is absolutely different
from the smouldering-type reaction of the salt itself resembling a volcanic eruption. Also addition of Mg to (NH4)2Cr2O7 can greatly facilitate the
ease and completeness of detonation. Hence, a binary mixture of Ammonium Dichromate/Mg with 80/20 Wt. ratio, can be effectively detonated with 15gr
PETN as a booster charge. Regarding Explosive
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Can magnesium be replaced by aluminum?
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Nitrojet
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Crystalline Ammonium dichromate in its pure state can not be ignited easily upon contact with open flame. It should be piled into the shape of a small
dome with a cavity at the top to hold a cotton wool previously soaked in Alcohol. Ignition of alcohol can generate enough heat to initiate a
decomposition reaction inside the mass of the Ammonium salt. Once it commenced, the reaction front proceeds very slowly through the bulk of the
unreacted material in a rather smouldering fashion than deflagration. Water vapor, gaseous nitrogen and chromic oxide are the major decomposition
products. The reaction is not however highly exothermic for its heat of decomposition is reported to be 310kcal/kg. When being ignited unconfined,
conductivity is the main mechanism of heat transfer through the column of the material. The heat front actually propagates from particle to particle
and such a phenomenon alongside with a relatively low heat of reaction are the main reasons for slow rate of reaction which in many cases also leave a
portion of material unreacted. Addition of atomized magnesium and aluminum hence can greatly improve the coefficient of heat transfer because of their
high heat conductivity. On the other hand ignition of metal powders can generate immense heat which yet further enhances the rate of decomposition
reactions. Part of the metallic ingredient consumes atmospheric oxygen for its ignition when the mixtures ignited in open. But the highly reductive
metals can also react with water vapor and chromic oxide to reduce them into gaseous hydrogen and metallic chromium respectively. I always can find
Chromium globules amongst the reaction reside especially when the mixture contains Aluminum. Needless to say that, such binary or ternary mixtures can
be employed in confinement to manifest their great explosive power. As I mentioned earlier they have a self-sustaining reaction even in total absence
of atmospheric oxygen so the zero oxygen balance of Ammonium Dichromate is not a problem. When such a charge is fired unconfined, the reaction zone
propagates again based on heat transfer but here the major transfer mechanism is Convection. While the linear rate of reaction does not exceed a few
centimeters per second in conductivity-based heat transfers, convection can increase the reaction rate to the extent that it exceeds the Mach number
or sound velocity at the given conditions. Addition of metals can again improve the rate of reaction, this time merely because of the great thermal
gradient resulted from their immense heat of oxidation. The drawback associated with these mixtures is their relatively low gas yield which can be
effectively overcome by addition of certain percentage of ammonium nitrate.
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Zinc
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Yesterday I got some ammonium dichromate from a friend and I tried to ignite it. It burns very nicely. Like a volcano. In the next few days I will try
different mixtures with it and report the results.
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Zinc
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Today I tried. Mixed with AL powder it burned like always. Al added no effect. With AL and S it burned like with AL only. The difference was that
when the remaining green powder that was left after burning would ignite in spots after being turned around. With AN and Al it also burned very
slowly like always only white smoke was produced from he decomposing AN. The Al powder was made from a failed Al casting and an angle grinder. The
ingredients were mixed in a mortar and pestle.
[Edited on 28-12-2007 by Zinc]
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Nitrojet
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I think the Aluminum powder which you prepared from grinder is not of adequate fineness. Try to use Aluminum Atomized which is in the form of a very
fine powder. Mix it with Ammonium Dichromate in 20/80 ratio.
When ignited in open, the mixture burns slowly, however, it behaves entirely different when ignited under strong confinement. I got some 20 pieces
from an elbow (made from cast iron) within which I put 15 gr of the mixture and then fired by means of a hand-made safety fuse. Nevertheless I think
such mixtures has no privilege over an ordinary chlorate or nitrate mixture.
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