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Author: Subject: Bromate, Iodates (sans the chlorates)
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[*] posted on 9-7-2019 at 10:21
Bromate, Iodates (sans the chlorates)


Hey everyone,

So I've been doing some experimentation on bromate/iodate salt oxidizers with some good success (for pyrotechnic colorants/oxidizers). I'm currently trying to get a grasp on what safety considerations must be taken into account when working with these oxidizers and was hoping some of you could shed some light. To start, I'll share the information that I know regarding the two oxidizers I've worked with and my thoughts. My hope is that the traditional concerns with chlorate oxidizers are negated while some of the more favorable properties are conserved. I'm not naive enough to know that this will be the same, but hopefully we can find some good conclusions. I'm not overly concerned about KIO3, however I do have some hesitation about Ba(BrO3)2/KBrO3.

Potassium Iodate
MW: 214.00
Melting Point: 560 C

My take: Decomposition into IO2 similar to chlorates decomp into some ClO2 doesn't seem likely since IO2 is highly unstable...typically in over-oxidized formulations I've seen more HI or I2 gas released. Higher melting point for this oxidizer, along with a net endothermic decomposition (~134 kJ/mol[1]) makes me believe that the chlorate/sulfur(sulfuric acid) reaction would not occur with this oxidizer spontaneously or violently. I don't have any concentrated sulfuric with me to test this theory.

As far as ammonium compound sensitivity goes, I can't really find a ton of information....I'd imagine that if the formation of Nitrogen Triiodide occured during decomp somehow, it would be a very bad time for everyone. But I can't find any info on whether the replacement reaction between KIO3 and, say ammonium chloride or ammonium perchlorate to form NH4IO3 would occur readily or if that product could spontaneously detonate.

Barium Bromate
MW: 393.13
Melting Point: 260 C

Potassium Bromate
MW: 167.00
Melting Point: 350 C

My take: I do have a bit more concern here due to the lower melting point that is similar to Barium/Potassium Chlorates. After doing some searching, I couldn't find much on the formation of Bromine Dioxide other than BrO2 being a very unstable solid.

It is, however, a bit better documented that Ammonium Bromate is an explosive material, however I couldn't find any information on how sensitive to friction, heat, shock etc. it is. I'd imagine that the lower MP of the bromate salts would make them more likely to go through replacement reactions in small quantities when in the presence of Ammonium compounds, so I have already gone out of the way to keep ammonium salts isolated from bromate salts.

Any information you guys have on these subject would be greatly appreciated. As I continue with my endeavors, I will likely be conducting the appropriate thermal, friction, and impact testing and will be sure to share my results there.

EDIT: In my initial post, I left out the importance of bromic acid generation and it's effect on a bromate/sulfur mixture in comparison to chloric acid generation and it's effects. The generation of chloric acid "which is a much more reactive oxidizer than its potassium salt and which readily decomposes to form the powerful oxidizer chlorine dioxide. If the chloric acid or chlorine dioxide oxidizes some other component of a mixture to produce an acidic product, an initially small amount of acid can lead to the generation of more acid and thus to a chain reaction that can ultimately result in ignition.[2]". I understand the acidification of a formula is never really a good thing, however since Bromine Dioxide is likely not forming and catalyzing the reaction, I didn't put too much thought towards this mechanism.

1. Brusnahan, J. S.; Shaw, A. P.; Moretti, J. D.; Eck, W. S. Propellants, Explosives, Pyrotechnics, 2016, 42 (1), 62–70

2. Sturman, B. T. In International Symposium on Fireworks; Puerto Vallarta, MX, 2019; Vol. 17th, pp 371–386.

[Edited on 9-7-2019 by ShotBored]

[Edited on 9-7-2019 by ShotBored]
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[*] posted on 9-7-2019 at 13:06


In a short performance update, the use of Barium Bromate in an NC color composition has yielded one of the purest blue flame's that I've seen. Additional chlorine donor was necessary (in the form of saran), however the flame temperature of the formulation seemed to be in the perfect range for the evolution of blue flame. When Barium Chlorate/Potassium Chlorate were replaced with Barium Bromate/Potassium Iodate in Bleser's Blue #1 composition, performance was similar to the original formula.

I am going to do a calorimetry study soon on the decomposition thermodynamics of barium and potassium bromate, as well as get an update on the sensitivities of compositions using these salts in comparison to their chlorate equivalents, but with so far the results are extremely impressive from a photometric standpoint.

EDIT: I should also mention that the NC/Barium Bromate composition DID contain copper compounds and that the barium bromide emitter was NOT emitting blue light....:D

[Edited on 9-7-2019 by ShotBored]
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[*] posted on 9-7-2019 at 13:52


Great work! There are some regulation issues and environmental issues with perchlorates being blown out of proportion. So we do owe it to look for new materials. My understanding was potassium periodate was the most promising.

I think the gold standard would be a oxidizer than can replace PP in flash powder comps.

The problem with potassium periodate is it’s high melting tempature and endothermic properties. The perchlorates are just damn good oxidizers.

There are a fantastic few pages on this issue in the latest 2019 book “Chemistry of pyrotechnics” by an author named Chris M.
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[*] posted on 10-7-2019 at 05:28


@MineMan Absolutely...the anti-perchlorate trend may not be entirely logical at its core, but give the people (mostly, the gov and California) what they want, right? :D

I haven't done any testing yet with flash compositions yet and probably won't for awhile....as expected, I'm typically wary of doing much with flash if I don't have to.

But I think the biggest attraction of, say, Potassium Bromate, is that it is already manufactured in bulk (for use as a rising agent/preservative from my understanding?) and that implementation won't be cost-prohibitive.

But yes, Mocella/Conkling's new addition of "Chemistry of Pyrotechnics" has been a great read so far...a lot of my inspiration for this product come's from the works of the LMU group (Klapoetke, Rusan, et al), Picatinny (Sabatini, Moretti, Brusnahan, Shaw, et al), and the Vilnius University team (Juknelevicius, Ramanavicius, et al). I attached Sabatini's Review paper provides a pretty good overview for the military's perchlorate replacement projects if it's of any interest to people.

Attachment: Sabatini-2017-Propellants,_Explosives,_Pyrotechnics.pdf (763kB)
This file has been downloaded 131 times

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[*] posted on 10-7-2019 at 09:52


Shot. Thank you for the additional information. This is IMHO one of the best posts of the year. Your really trailblazing here.

What’s wrong with flash in 1 gram quantities?
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[*] posted on 10-7-2019 at 11:31


@Mineman

So I did decide to try a 1g flash mix with the barium bromate....I used the "Japanese flash thunder" listed in Mocella/Conkling (pg 213):

43% Ba(BrO3)2, (97% assay)
26% Sulfur
31% Aluminum, 10890 Flake

Comp was put in a pan unconfined and ignited via fuse from a healthy distance....it definitely deflagrated rapidly with very little residue left, was accompanied by no report.

I'm sure if it was confined, you'd get a nice crack. Again, I have to say that the barium bromate/sulfur comparison to chlorate/sulfur sensitivity is only conjecture and isn't based off of actual experimentation. That being said, I'm sure people more familiar with flash comps could likely find great use here.

[Edited on 10-7-2019 by ShotBored]
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[*] posted on 10-7-2019 at 20:53


Excellent work!

My real question is if it’s capable without the sulfur. Sulfur is a poor fuel and one with incompatible with other fuels....

See. I am in love with super flash mixtures, but they are all perchlorate based.... ammonium periodate would be interesting.

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[*] posted on 11-7-2019 at 06:57


I don't really know a ton of chlorate flash mixes off the top of my head, I'd imagine that those classic chlorate/Sb2S3/Aluminum (47:6:47) flashes of old times would likely work just as well with bromate, only without the sensitivity issues hopefully.

If I get that time, I'll retest with just a 69:31 Barium Bromate/Magnesium flash mix and let you know how it goes.

My Potassium Bromate should be getting here today or tomorrow so hopefully next week I'll have some more results there.

I did have some potassium periodate sourced, but the price was a bit crazy so I never pulled the trigger on it. The melting point is a bit high so I dunno if the reactivity would be as good. But making some ammonium periodate from there wouldn't be too difficult. I have a feeling that it's likely quite energetic haha.
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[*] posted on 11-7-2019 at 10:44


I once read the following:

Playing with chlorates in pyrotechnics is like playing with a poisonous snake, playing with bromates in pyrotechnics is like playing with a poisonous snake, which is slightly pissed off.

-------------------------------------------------------

I tried some energetic experiments with bromates on a small scale (100 mg or so) and my experience is that mixes with bromates are quite energetic, but also quite sensitive. I am afraid that bromates do not have a real place in pyrotechnics, too dangerous.
For little fun demos bromates can be quite interesting. I once did an experiment with Ba(BrO3)2 and CsBrO3 and with these you indeed get very saturated colors. Using these in real fireworks most likely is not wise. CsBrO3 also is prohibitively expensive.

-------------------------------------------------------

Iodates are quite tame, compared with both chlorates and bromates. With red phosphorus they do burn and such mixes can be ignited easily, but with sulphur the mix is not really energetic. I did not test with metal powders, but I can imagine that a mix of KIO3 and Mg or KIO3 and Al can be very energetic. Pyro mixes with iodates do give interesting smoke. Sometimes beautiful purple smoke, which turns yellow in a few seconds.

Periodate is much more energetic than iodate. However, for pyrotechnics it is totally useless. It is even more sensitive than bromate. Besides that, periodates are very expensive.

------------------------------------------------------

Ammonium bromate is dangerously unstable. On heating, it quickly decomposes, nearly explosively. Ammonium iodate is more stable. It even is commercially available (e.g. at chemcraft.su). Ammonium iodate does decompose on heating, but not explosively. Once the reaction starts, it continues, producing a lot of purple vapor of iodine. It is sufficiently exothermic to provide its own heat, once started.

Ammonium periodate is quite interesting. It is easily formed from ammonia and periodic acid in water. On evaporation a white solid remains behind. This solid decomposes very violently on heating, producing a lot of iodine vapor. It is too unstable and too dangerous to keep around for a long time. Nice to do a little experiment on a 100 mg scale, but not safe to make in large quantities and keeping around.




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[*] posted on 11-7-2019 at 10:58


@Woelen

I know i've seen somewhere on this forum before that bromate salts were discussed, but I can't find that thread. Academic findings using bromate salts are becoming more prevalent recently though, which I think merits taking a second look at things.

One of the IPS papers from the LMU/Vilnius University team DID mention some shock sensitivity concerns (~40 N range). I will definitely be verifying those results and keeping a special eye on friction sensitivity as I continue experimentation.

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[*] posted on 12-7-2019 at 03:05


Curious and interesting.
Hygroscopicity of the mixtures should be interesting too.




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[*] posted on 12-7-2019 at 07:26


@Herr Haber

Solubility of Barium Bromate in water is 0.788 g/100mL at STP. Potassium Bromate solubility is 6.9g/100mL at STP, so a slight potential for hygroscopicity issues, but nothing like the problems in Strontium Nitrate or Potassium Nitrate.
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[*] posted on 12-7-2019 at 07:32


All,

Yesterday I did some granulation of a NC/Barium Bromate Blue formula I had been perfecting while waiting for my Potassium Bromate. As always, safety data first!

Friction Sensitivity: 108 N
Impact Sensitivity: >10.4 J

Will be doing thermal stabs over the weekend.

I shot them side-by-side with my old NC/AP blue formula and performance was for the most part indistinguishable. If thermal stabs go well over the weekend, I think the German/Lithuanian/Picatinny research is definitely onto something here that could be a big replacement for traditional chlorate compositions.

I have the plan to test some well mixed sulfur/Potassium Bromate for friction sensitivity to see if we are are even ballpark to the traditional chlorate/sulfur sensitivity problems.
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[*] posted on 1-8-2019 at 05:55


ShotBored stated:

"But I can't find any info on whether the replacement reaction between KIO3 and, say ammonium chloride "

Perhaps, no need too, trying careful mixing of the dry compounds in a very small amount, wrap in, say, an Al foil ball, and toss it into a fire.

Related combination mix of NaNO2 and NH4Cl is employed as a flame-less explosive for blasting in mines (where they may be a CH4 presence). See comments and references at http://www.sciencemadness.org/talk/viewthread.php?tid=78873#... .

Why the mixed salt approach resulting in an in situ prep? Because some compounds are rightly designated too unstable/sensitive and extremely energetic to work with!
--------------------------------------------------

I recently tried out a new prep creating an iodate from a few KI pills. Quite a blinding flash when a very amount amount was mixed with iron filings!

The energetic test was needed to validate the science behind the innovative path, see https://www.sciencemadness.org/whisper/viewthread.php?tid=15... .

[Edited on 1-8-2019 by AJKOER]
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[*] posted on 2-8-2019 at 08:23


@AJKOER

I'm hopefully closing in on a conclusion on the Bromate/Sulfur sensitivity investigation and I've learned a ton so far. I'll share some of those findings here once I've reached a more solid conclusion, then I'll begin an in-depth look into the ammonium compound/bromate or iodate sensitivity. I'm sure the reaction occurs readily there, so for now I've been operating under the assumption that ammonium compounds and bromates are a no-no.

Friction results for mixes of sulfur and potassium bromate are very low....<20 N! Obviously great care, or avoidance of intimate mixtures with sulfur, need to be put in place. However stability tests so far have shown no sign of spontaneous decomposition over time like sulfur/chlorate mixes. This makes me feel ok about bromate compositions in a device with black powder

Still have a ways to go with this before I draw any major final conclusions.
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[*] posted on 3-9-2019 at 00:19


i did test KBrO3 with MgAl 325#, nothing fancy, weaker than KClO3.
making bromate is a pain in the ass, it tore apart my MMO electrode. possibly too high bromine concentration (add excess NaOH? lower KBr conc?) it may also have been temperature issue.
as for iodate, forget it. KIO4 and sugar however goes off well with sugar, very impressive open air deflagration, but no actual bang.

Na2S2O8 has also been attempted used as flashpowder but it didnt give a very impressive bang in comparison to the usual compositions
i may add that for a great report you wanna aim for moderate OB negativity
KBrO3 must be kept far apart from red phosphorus, Dornier335A found it that it was too sensitive to even mix carefully as it would ignite with minimal friction, this could hint at it being more unstable than KClO3 with also metallic fuels- could.




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https://en.wikipedia.org/wiki/Solubility_table
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[*] posted on 9-9-2019 at 08:41


@Antiswat

Thanks for the information. I simply purchased the KBrO3 since it's widely available. And I too have had little success with iodates.

I've done weeks of testing since my last posts on this subject and have a few more things to share.

All in all, my potassium bromate seems to function great as a direct 1:1 replacement for potassium chlorate. As Antiswat mentioned, it seems to be slightly weaker than KClO3, however I have one major distinction to share.

In accordance with ISF 2015 paper about stability in storage for materials with a 3-year model, I ran a 14 day stability at 75 degrees C with a bromate/NC (with stabilizer) formulation pressed into stars and coated with a standard black powder prime. I also ran a control sample with a different, sulfur-free prime. I monitored sample mass loss and pH daily over this period and noted NO statistical difference in mass or pH between the black-powder coated samples and the control samples. Performance in a device was almost the same between the two and mass loss was in acceptable ranges that would not indicate decomposition

I know this is not a definitive test, however this with all the other sensitivity tests I've done between potassium bromate and sulfur so far seems to indicate that the two compounds do not decompose in the same way that chlorate and sulfur compounds do.

I hope some others begin their own experiments and share info. I think this compound has been overlooked for quite some time and possibly given the same associations in instability as sulfur/chlorate mixtures which has kept it from good investigation. But the German team at LMU are looking into it for replacement of perchlorates and while they haven't released any information on anything they've learned about sensitivity, I don't think it would be something of interest if it was going to cause a major change in standard practices (I'm likely wrong here, but I'd like to think some researchers take this into account when using military grant money).
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