Chlorates - Sulphides and Sulphates Incompatibility

[AustralianPyromaniac]

Does anyone have an idea of chemically why chlorates and sulphIDES are an incompatibility? 

I am sure I have read some reasoning before, but cannot find it now. 

They release H2S gas if exposed even very weak acid, H2S is much more acidic than, for example, tap water. This may cause a chain reaction that can decompose chlorates if slightly acidic chemicals or solvents are used, but I cannot find any info, this is just a guess. 

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Also, contrary to what is sometimes said, I am under the impression that chlorates and sulphATES (with the exception of copper sulphate) pose no more danger than any other compound, such as a carbonate, as the sulphur is fully oxidized, pH-neutral, and Ba/Sr sulphate are also completely insoluble. Can anyone speak to this with some hard data? 

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@Mumbles on the post I am recalling I think you were the person speaking about this issue. 

 

[mx5kevin]

See this: Destroying Chlorate with chemicals

I myself would certainly not put anything like that in compositions. It makes the composition extremely sensitive to friction, impact, and unstable in terms of storage. There are special compositions such as the match head, where potassium chlorate is mixed with sulfur professionally wetting with glue. In amateur circles, there are people who mix potassium chlorate with sulfur or antimony trisulfide. Such things can also be found in pyrotechnic recipes from very old dubious sources. But this increases its sensitivity to friction and impact in an extraordinary way. If the composition contains some moisture it increases the sensitivity even further. However, nobody does that in professional circles. Minxing for pyro compositions sulphides and sulphates with chlorates I haven't heard from others. The problem is that chloric acid can be released from chlorates. In laboratory conditions, what professionals test and document is what I believe for such mixtures. At home, what amateurs come up with in many cases completely contradicts what professionals describe, and this will appear as a problem for them later on. If professionals detailed documenting something with Ba/Sr sulphate and some chlorate I believe them. For perchlorates I use Na and K metabisulfite, added to it proportionally HCl when boiling. Without proportional addition of HCl and boiling, Na and K metabisulfite alone does not completely neutralize chlorates. A lot of sulfur dioxide must be released here. This completely neutralizes the chlorate contamination. By washing the crystals twice with cold water and 2X recrystallization, possible sulphide, sulphate, acid and other contamination can be completely removed from KClO4 or NH4ClO4. If you boil some potassium or sodium chlorate contiminated perchlorate for two to three hours, for example, in a 5% hydrochloric acid solution or adding more, it will not completely decompose for you. Stored in a cool, dark place some diluted NaClO3 solution with some HCl, the whole thing will also not decomposing.

Edited July 21 by mx5kevin

[AustralianPyromaniac]

To your first point, I have made quite a number of star comps with sulphur, and while they are sensitive to shock, they are really not that sensitive. A heavy and direct hit from a hammer is required to detonate them, and even then sometimes they do not go off.  I have also never been able to ignite a single sulphur chlorate star with friction. Grinding the stars against concrete does nothing. Matches also contain chlorate and sulphur as you say, along with sulphides - and these are not known for spontaneously exploding. If non-acidic sulfur is used, the risk is much much less than people claim - the idea being that these mixtures explode if you even look at them wrong. Two points I would make are 1) barium chlorate stars seem to be way more sensitive than K chlorate 2) the auto-ignition temperature of chlorate sulphur stars is way lower than chlorate stars without it, low enough even the reflections on a summer day may very well be able to set it off. Where I live there is quite limited availability of pyro chemicals, and I have probably experimented with chlorate sulphur mixtures more than most. I think we make far too much out of the risk, and a lot of myths have circulated in the name of safety. 

Sulphides (and a small amount of sulphates) are found as impurities (1%-2%) in pottery store BaCO3 and SrCO3. And this is why I want to know the mechanism of sensitisation. I have made stars with these pottery store reagents, and found absolutely no measurable difference in sensitivity compared to pure chemicals, but the risk may be something that only happens over time, or it may be simply not that big a risk. 

As always appreciate your input, very interesting comments on the chemical breakdown stuff

Edited July 22 by AustralianPyromaniac

[mx5kevin]

KClO3 Mg S combinations are particularly sensitive for friction. If it is not properly coated with linseed oil the Mg, it can easily catch fire by itself. If ethyl alcohol is added, it significantly increases its sensitivity for friction. I tried many oxidizer metal sulfur combination in flash powder, but nothing starts to ignite from friction so easily than Ba(ClO3)2 and KClO3 when a small amount is in a mortar pestle tested. It is even famous for its instability KMnO4 Al S combination in a mortar pestle rubbed it withstands friction well compared to it. I know of multiple case when KClO3 compositions caught fire when someone at home was working with them. And KClO3 has a special feature some compositions what can explode, it can intensive way explode when pressed, which will tear your fingers off and make you deaf. The compressed block can explode (almost like a detonation)  with great force. 10g COMPRESSED in to a block (in a tube) KClO3 flash can be heard from more than a kilometer when it explodes. A small amount of flash initializes the rest of the compressed array quickly like a blasting cap. You can get a lead dioxide anode, or there are companies making laboratory platinum electrodes. A 3mmx70mm silver rood they are fully overcoating with 200 micron 0,2mm thick way with pure platinum which will never break for any chlorate and perchlorate. With KClO4 there is no such problem. But if this would be complicated, just because you can't buy potassium perchlorate doesn't mean you can't buy 1000ml 70% perchloric acid either (It is somewhere very expensive, but somewhere will in the same price if mix it with KHCO3 than buying 1000g KClO4). But where there is an alternative, I never use there chlorates.

Edited July 22 by mx5kevin

[Crazy Swede]

On 7/21/2024 at 6:32 AM, AustralianPyromaniac said:

Does anyone have an idea of chemically why chlorates and sulphIDES are an incompatibility?…Can anyone speak to this with some hard data?…

 

I have good explanations from private communication with a well known pyrotechnist. I’m away from my computer right now but if I don’t forget I can come back about to this issue in 3-4 weeks. 

[AustralianPyromaniac]

33 minutes ago, Crazy Swede said:

I have good explanations from private communication with a well known pyrotechnist. I’m away from my computer right now but if I don’t forget I can come back about to this issue in 3-4 weeks. 

Thanks! I'd really appreciate that. 

[pyrodivision]

My experiment contain chlorate + sulphur, i make pull ring igniter and make matche head

my composition for pull ring igniter is contain chlorate and sulfur + red phosporus, mix just little composition maybe 1gram, and just 15 miligram in 1 cap.

I understand that Armstrong mix is very dangerous, that's why I only make a mixture of 1 gram in each of my experiments ans make it slurry with water and bind with arabic gum, 

but when I kept it for about 2 months, there was a change, the mixture came out like a black liquid, and that made it difficult to ignite, i try to change bind with NC but and thats still it, 

in my composition contain 25-30% sulfur

I have also experimented with making match heads, but for matches I only use 8-10% sulfur, and it works fine when I store it for a long time.

For now I will try to reduce the sulfur in my pull ring mixture to 8-10%, 

 

[AustralianPyromaniac]

Gum Arabic sours quite quickly and becomes acidic. Not sure what was going on in the NC-bound ones. Maybe Armstrong mixture is simply not something that can be stored. Not an area of expertise for me, but interesting work. 

[AustralianPyromaniac]

On 7/22/2024 at 9:13 PM, Crazy Swede said:

I have good explanations from private communication with a well known pyrotechnist. I’m away from my computer right now but if I don’t forget I can come back about to this issue in 3-4 weeks. 

Following up on this

[Crazy Swede]

Ah, I completely forgot. Will start digging it up!

[Crazy Swede]

Ok, I se now that the explanation I once got was related to organic sulphur compounds with chlorates.
 

Anyway, according to my reference, using sulphur compounds where the oxidation number of the sulphur is -2 is dangerous in combination with chlorates. 

The reason is that the activating energy for decomposition of the chlorate is lowered. The composition simply gets more sensitive to all stimuli!

If the sulphur compound also is sensitive to oxidation, turning pH low when moisture is present, sulfones will be created and thereafter sulfonic acid that will start an auto catalysis of the decomposition of the chlorate. The risk of self ignition gets very high!

But, in my own opinion, ordinary antimony trisulphide (Sb2S3) and probably iron sulphide (FeS) should be stable together with chlorates, although they will make the compositions much more sensitive. 

[cmjlab]

7 hours ago, Crazy Swede said:

....sulphur compounds where the oxidation number of the sulphur is -2 is dangerous in combination with chlorates. 

Not having a formal chemistry background, I did some reading because your statement above interested me and I was curious what organic sulphur compounds (OSC) actually have a -2 oxidative state. 

I read through an educational reference** stating the  OSCs with a -2 oxidative state are:  -thiols, -sulfides, and sulfonium ions (no idea what the last one is). 

Based on that, wouldn't the "trisulfide" of Antimony fall into this category?  Or is it because it's not very soluble in water and therefore less likely to react in the presence of some moisture? Or minimal moisture where it may be competing with a more soluble compound?  Thanks for bearing with me.  

Chuck

**Reference:  https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Book%3A_Virtual_Textbook_of_OChem_(Reusch)_UNDER_CONSTRUCTION/14%3A_Thiols_and_Sulfides

 

[Crazy Swede]

@cmjlab, first of all, I mixed up the situation of organosulphur compounds and inorganic sulphur compounds. The problem of creating sulfones and sulfonic acid due to oxidation is only related to a certain type of organic sulphur groups. Unfortunately I cannot discuss them openly.

When dealing with ordinary sulphur or inorganic sulphur compounds, the route to auto catalysis goes over different pre-stages to sulphuric acid.

The average oxidation state of the sulphur in antimony trisulphide is -2 but as you say, because of its low solubility there will not be much acid formed until heated above what is normal for drying and storing of pyrotechnics. But it still increases the sensitive to friction enormously when added to chlorate compositions.

Edited August 29 by Crazy Swede

[cmjlab]

On 8/28/2024 at 1:25 PM, Crazy Swede said:

 

Appreciate the response, that makes sense concerning the increased sensitivity of chlorate / Antimony trisulfude combinations.  That's really the only two I use together routinely anyways based on what I was reading about last night.  

As for the rest of the compounds, I probably wouldn't understand even if you could talk about them openly, due to my limited knowledge on the subject.  

Thanks again!

 

 

 

[Soloserly]

Per Vouter Visser:

"Chlorates and sulfur. Mixtures containing both are not only very sensitive to friction and shock but are also known to ignite spontaneously. The sulfur reacts with water and air to form trace amounts of sulfuric acid. This will react with chlorates to form chlorine dioxide, a yellow explosive gas that will ignite most flammable materials upon contact. Addition of small amounts of barium or strontium carbonate to chlorate based compositions is sometimes done to prevent buildup of acid, even in compositions without sulfur. Many older texts on pyrotechnics describe the use of chlorate/sulfur based compositions. Today, many alternative and much safer compositions are available and there is therefore no excuse for the use of chlorate/sulfur mixtures. This also means chlorate based compositions cannot be used in items that also contain sulfur based mixtures. For example: chlorate based stars cannot be primed with black powder. Nor can a H3 burst charge be used with black powder primed stars (or stars containing sulfur)." 

I realize the original question was about sulfates and sulfides, but the above may be one source of all the chlorate/sulfur lore that circulates online.  He goes on to describe three other Chlorate incompatibilities as well.  

Edited August 30 by Soloserly

[Crazy Swede]

The citation of Vouter Visser (who is that by the way?) is not completely true!

Chlorate stars can be, and have been for a very long time, primed with black powder without creating big risks. Look at the Italian and Maltese fireworkers!

The combination of modern, non acidic, sulphur is definitely possible as long as you know what you are doing. 

However, adding a small amount of magnesium oxide is wise, unless the composition already contains carbonates or other bases that can act as a pH buffer. 

[Mumbles]

I assume he meant Wouter Visser.  He used to run a popular pyrotechnic information website, but I don't know anything about his background or credentials.