making potassium (per) chlorate

[Bonny]

Some good news on the perc making front!

I dissolved/filtered/recrystallized and washed almost 5lbs of raw perc...it was a real PITA as the solubility is ~200g/l @100C. I did use some extra water, maybe 1l total. The solution was cooled, but not to 0, probably 3-5C, but not really sure. After harvesting with my new vacuum filtration rig- pics to follow, I did a few tests with NPAA - see Swede's blog.

 

I tested a sample of the water left over from recrystallizing, which tested positive for chlorate, turning a pink colour.

I then tested a small perc sample, which tested negative. To this I added a pinhead sized pc of chlorate, and the colour instantly changed to pink.

I will do a few more tests witha larger amount dissolved in water before I conclude anything.

Also, a silver nitrate test showed no chloride present.

 

This is leading me to believe that KClO4 could possibly be cleaned by recrystallization only

[Arthur]

It's fine to recrystalise and wash to purity as you can return all the washings to the tank later made up to full strength.

[Bonny]

It's fine to recrystalise and wash to purity as you can return all the washings to the tank later made up to full strength.

 

I know it can be recycled, but I just dumped mine... I got tired of so many different buckets around and I won't be making perc again anytime soon as I fried my (second) Pt anode.

[pdfbq]

Hi,

Anybody out there knows if testing with Indigo Carmine is as sensitive as the NPAA test?

Indigo Carmine seems sensitive, just wonder how sensitive it is.

[Bonny]

Hi,

Anybody out there knows if testing with Indigo Carmine is as sensitive as the NPAA test?

Indigo Carmine seems sensitive, just wonder how sensitive it is.

 

I think it may be even more sensitive. See here:

http://www.oxidizing.110mb.com/chlorate/tests.html

[pdfbq]

I think it may be even more sensitive. See here:

http://www.oxidizing.110mb.com/chlorate/tests.html

Tnx Bonny, I have it because of this site. Its easy to get, much easier than NPAA (at least here in Holland) so I was wondering why you guys prefer NPAA.

[Bonny]

Tnx Bonny, I have it because of this site. Its easy to get, much easier than NPAA (at least here in Holland) so I was wondering why you guys prefer NPAA.

 

I think it was Swede that got going with and developed a good test using NPAA. The tests are much easier to perform, and don't require any boiling of HCl.

You are right about acquiring NPAA being most difficult though.

[Swede]

 

I tested a sample of the water left over from recrystallizing, which tested positive for chlorate, turning a pink colour.

I then tested a small perc sample, which tested negative. To this I added a pinhead sized pc of chlorate, and the colour instantly changed to pink.

 

 

This is very cool news. Now we need to know EXACTLY how you washed the raw xtals pulled from the cell, because that is an important part of the process. Perc xtallizes in the cell very fine, like table sugar or finer, so in theory, unless chlorate is trapped inside, a decent washing should remove the bulk of the chlorate, and a recrystallization finishes the job.

 

I am going to look into a lab cylinder and regulator containing SO2 gas. It might ultimately be cheaper than a salt like metabisulfite. Bubble the recrystallization water while cold, as the SO2 is more soluble at cold temps. With the water loaded with SO2, begin the heating to dissolve the perc, maybe bubbling a bit more as you go, then shut it all off, cool, and the perc should be exceptionally clean, on the order of the fabled Swedish perc instead of the crappy cheap Chinese perc. The star color difference is something only an expert (not me) can see and appreciate, but it is a worthy goal.

 

On the NPAA test - the reason I went with that is because it is a quick spot test and even a field test with nothing more than 2 dropper bottles. Very much like a pool chlorine test, a no-brainer. I have Indigo carmine, but have never even bothered after verifying the sensitivity of the NPAA test. If unable to source NPAA, then indigo carmine, a common biological stain, would be the way to go. Just watch out for boiling HCl - nasty fumes.

 

The other issue is that these tests may be TOO sensitive. There's no point in flogging one's self to go from 99.8% pure to 99.999%, if 99.0% pure is perfectly safe from a pyrotechnic standpoint. I am walking evidence that it is too easy to get wrapped up in this process, and one must remember the idea is to make oxidizer for pyrotechnics, not ultra-pure lab-quality reagents. But it IS fun, no doubt.

 

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

 

Head's up, guys. I am always on the prowl for suitable, heavy-duty power supplies, and there's a guy in Arizona with no less than 8 of these...

 

TDI Rackmount 4.5 - 5.5V, 50A supply, $24.99, guaranteed not DOA. Looks like a linear supply, shipping will probably be a mother, and it is at $38. If it is linear, not a switcher, it'll probably be more durable, less twitchy.

 

That is a smoking deal for a chlorate-only supply. You can barely buy a PC PSU for that money. I have no idea about this unit or how to alter the voltage (probably a trimmer pot), but still a decent deal.

 

Edit: forgot the link: Power supply

 

Item number 370277053554 on the US eBay site.

Edited April 20, 2010 by Swede

[WSM]

Head's up, guys. I am always on the prowl for suitable, heavy-duty power supplies, and there's a guy in Arizona with no less than 8 of these...

 

TDI Rackmount 4.5 - 5.5V, 50A supply, $24.99, guaranteed not DOA. Looks like a linear supply, shipping will probably be a mother, and it is at $38. If it is linear, not a switcher, it'll probably be more durable, less twitchy.

 

That is a smoking deal for a chlorate-only supply. You can barely buy a PC PSU for that money. I have no idea about this unit or how to alter the voltage (probably a trimmer pot), but still a decent deal.

 

Edit: forgot the link: Power supply

 

Item number 370277053554 on the US eBay site.

 

Very cool! Being a sucker for a good deal, I snapped one of these up. I'll report on it's properties when it arrives. Swede, PM sent.

 

WSM

[WSM]

Have you given any more thought to pH? Even the simplest possible system that I can think of would require a pump for the liquor, another pump + vat for 3M KCl, OR... a mechanized system that will lift the probe clear of the KCl, dip, measure, then return to the pure KCl (solution, I presume).

 

The more I think about it, the more I like the alternate suggestion of mechanically moving the pH probe into and out of the test chamber. I still feel I'd like to isolate the probe from the active (chemically and electrically) portion of the reaction chamber but at the same time run the controller continuously for real-time control of the pH. I was thinking of using pneumatic cylinders to drive inert plastic components in the system, without exposing them (the metal cylinders, I mean) to the harsh environment either. I like Swede's use of homemade teflon bearings and seals and may try that approach as well. Maybe PVC, CPVC or Kynar components moved through PFTE bearings would be best? Any thoughts?

 

WSM

[pdfbq]

I am going to look into a lab cylinder and regulator containing SO2 gas. It might ultimately be cheaper than a salt like metabisulfite. Bubble the recrystallization water while cold, as the SO2 is more soluble at cold temps. With the water loaded with SO2, begin the heating to dissolve the perc, maybe bubbling a bit more as you go, then shut it all off, cool, and the perc should be exceptionally clean, on the order of the fabled Swedish perc instead of the crappy cheap Chinese perc. The star color difference is something only an expert (not me) can see and appreciate, but it is a worthy goal.

I do it the sodium way so things are different a bit, but sodium metabisulfite is verry cheap in Holland (2 euro 1 Kilo) and I use 5% of the initial chlorate weight and never had to use more. I put it in the cold perc/chlorate solution and then boil it. All takes about 15 mins. I expected it to be difficult but its very easy.

 

On the NPAA test - the reason I went with that is because it is a quick spot test and even a field test with nothing more than 2 dropper bottles. Very much like a pool chlorine test, a no-brainer. I have Indigo carmine, but have never even bothered after verifying the sensitivity of the NPAA test. If unable to source NPAA, then indigo carmine, a common biological stain, would be the way to go. Just watch out for boiling HCl - nasty fumes.

I found there is not much difference in boiling or cold HCl, just the speed of the test. Boiling in about 0.25 sec , cold about 1 sec.

 

The other issue is that these tests may be TOO sensitive. There's no point in flogging one's self to go from 99.8% pure to 99.999%, if 99.0% pure is perfectly safe from a pyrotechnic standpoint. I am walking evidence that it is too easy to get wrapped up in this process, and one must remember the idea is to make oxidizer for pyrotechnics, not ultra-pure lab-quality reagents. But it IS fun, no doubt.

Its not too sensitive i think. Here are my simple results

Tube 4 is my cleaned KClO4, 5 is commercial perc and 6 is my perc with a pinhead of KClO3

 

I just was worried my Indigo test might not be good especially because the cleaning of the perc/chlorate went so easy but now I'm starting to believe i'm fine.

Edited April 21, 2010 by pdfbq

[Bonny]

This is very cool news. Now we need to know EXACTLY how you washed the raw xtals pulled from the cell, because that is an important part of the process. Perc xtallizes in the cell very fine, like table sugar or finer, so in theory, unless chlorate is trapped inside, a decent washing should remove the bulk of the chlorate, and a recrystallization finishes the job.

 

Here is how I process the raw perc from the cell: ALL water used is distilled

1) Cool the cell bucket in the freezer to maybe 3-5C (did not have any ice forming in the water)- I think the extra few degrees above 0C allows more chlorate to remain in solution

2) Decant (dump) off most of the water- AFTER carefully scraping any x-stals from the sides of the bucket and allowing them to settle.

3) Scoop/dump them into my washing bucket with 200mesh screen and allow to drain. It drains better sitting on an angle with an occasional stir and shake

4) Wash thoroughly with cold water from the fridge (and optionally cold water/alcohol) Add enough water so that it completely covers the x-stals and stir as it drains.

5) Allow to drain and dry the x-stals- could vacuum filter at this step to speed drying

6)Dissolve/filter/recrystallize -use ~10% extra water and then chill the water (again not to 0C)

-the extra water helps dissolve the perc as well as it should keep a bit more chlorate in solution when chilled

7) repeat step #3 - I know I have some loss using 200 mesh, but it is minimal- as I did re-filter this water through a coffee filter and there was almost no more perc recovered.

8) wash thoroughly with cold water, then cold water/alcohol- I used methyl hydrate (methanol).

9) drain and dry- I used my vacuum filtration set up this time and it worked quite well. What I used is simply a plastic dollar store strainer and a pc of pipe sealed into a bucket lid. Put a coffee filter into the strainer, fill with wet x-stals and use your shop vac in the pipe. I'll post a pic later.

10) Dry and do some testing

 

I have yet to dissolve a larger amount (maybe 200g) and test so I'm not completely sure that I have indeed purified it enough, but will get that done in the next few days. and post my results. I'm pretty confident that if needed, another recrystallization would finish the job.

 

EDIT:

I did another test today. I dissolved 50g of my perc in 1l of water (~50C) and it showed some very slight colour in 2 of 3 test tubes. One was slightly yellow and another had an almost invisible pink tint...indicating some chlorate was still present. I then added (an immeasurable) amount of chlorate to the pot, which produced a pink colour in tube #4.

I then added 0.5g of chlorate to the pot and the colour was VERY pink

This leads me to beleive that my perc (should) be usable as is, but another recrystallization should make it very pure. If the mil spec alows 1% chlorate, that would be equal to the 0.5g I added to the sample I tested, which would be quite a lot IMO.

Now I need to decide IF I should use as is, and/or for further batches if it would be easier to simply dissolve once, chemical clean with metabisulfite or do several recrystallizations...

 

EDIT#2: I just realized I did not check (or adjust if needed) the ph of my perc... I guess everything I have is going to get 1 more dissolve/recrystallization. I will test again, but at that point I think it should be pure enough for use.

 

Opinions???

 

 

 

 

I found there is not much difference in boiling or cold HCl, just the speed of the test. Boiling in about 0.25 sec , cold about 1 sec.

 

 

So the test does work cold? i might try that as well, but was not really interested in doing any more boiling for tests, especially HCl.

Edited April 21, 2010 by Bonny

[pdfbq]

So the test does work cold? i might try that as well, but was not really interested in doing any more boiling for tests, especially HCl.

I have not tested it thoroughly but I definitely get results when testing cold. I do 1ml HCl and about 4 drops of the Indigo Carmine stock in a test tube.

Then some drops of the dissolved perc and shake. It works. When you heat it is an instant color change, cold some secs. I don't know if cold is as sensitive as hot though.

 

edit:

Today did some cleaning with sodium metabisulfite and testing.

After a little boiling of the substrate with sodium metabisulfite

Test 1: cold tested positive on chlorate

Boil a little longer (the substrate with the sodium metabisulfite)

Test 2: cold tested negative on chlorate

Test 3: hot tested negative on chlorate

 

There is one thing I do not understand is that I use only 15 grams of sodium metabisulfite on an initial 580 grams of NaClO3 (before cel run) and that it seems to be enough.

Not this time only, but all the runs id did (this is the fourth)

Edited April 24, 2010 by pdfbq

[Swede]

I'm sorry I haven't been more active on this thread. It is GREAT to see alternate testing and cleaning methods. I'll need to give the indigo carmine test a try. The only thing that held me back was that hot HCl fumes KILL my shop, because I combine machine tools and such with this pyro hobby. The damned HCl destroys any exposed steel. Very annoying. But if it works cold (and it makes sense that it should, as temperature simply accelerates a reaction that will occur regardless), I'td be a great addition to our suite of tools, due to NPAA being difficult to source.

 

I've gathered than anthranilic acid is one of those druggie chems. N-phenylanthranilic acid is perhaps close enough so that suppliers can be tight.

 

On chlorate contamination - SAFETY is everything. Any residual chlorate, if safe, will not wash out colors or cause problems as other contaminants might. The more I think about it, the more I'm leaning towards Tentacle's discovery that mil-spec perchlorate is 1% contaminated, and being ex-military myself, I have a perhaps unfounded faith in mil-spec. In general, it means overly built and/or overly safe. My gut says that one recrystallization, with perhaps a pinch of metabisulphite or SO2 gas, should be entirely adequate. For bulk recrystallizations, due to the poor solubility of K-perc, I think a guy needs to rig up an industrial tank, and I'm thinking stainless turkey fryer over propane or gas. Those things probably hold nearly 100 liters. Any use of glassware and beakers is only acceptable for tests, I'm thinking.

 

Don't forget a neutral to alkaline pH during the process, just prior to cool-down.

 

Cooling a 100 liter stainless vat is going to be a bitch. Either a dedicated fridge, or a plastic tub with a lot of ice water would do, but in any case, bulk purifications are going to be a hassle.

 

WSM, I'm glad you bought one of those supplies, and I'm very curious about your review. See if you can find a manual online. I'll bet there is a trimer pot in there somewhere that allows voltage adjustment, and that would be a real boon, as there is a huge difference between 4.5 and 5.5 V.

 

He has seven left. It LOOKS to be an awesome deal, even with shipping. All I can say is monitor current, as closely-spaced electrodes might crack 50 amps, and the supply may run very hot indeed. A fan or two over the supply will definitely help.

 

For those I've been PM'ing lately, I'll be gone for 4 days, so please understand if I don't respond quickly.

 

Good work, and good luck, fellas.

 

Swede

[Mumbles]

For brewing, people use immersion chillers. Basically a long coil of stainless steel (for this application), that you run cold hose water through. Something like that should be able to cool down the solution over a matter of maybe 20 minutes if you prechill the water with a cooler full of ice water.

[Arthur]

Do your bar (drinks!) fittings include beer chillers? (refrigerated unit with beer pipes in a cold block) Run the solution into a tank cooled with water at 2C or antifreeze at -10 for quicker cooling.

[Bonny]

For the chemists....WTF happened here??

 

I was doing a chemical clean using potassium mteabisulfite on a batch of raw (un-recrystallized ) k-perc. I dissolved 250g in 1.5l of water with 10g of K-meta added while cold in a SS pot. I think I had significant chlorate contamination in the perc. Anyway, it was still testing strongly (deep pink/red colour) for chlorate. I continued adding ~20% k-meta solution, about 25ml at a time for a total of 40g of k-meta. When I added the last 25ml or so, all the sudden, the solution turned blue/green and started to gently and "frothy" boil.

I neutralized the (greenish) solution with KOH to ph 8. There was a green/brown/black ppte in the water.

I then filtered through a stack of coffee filters, yeilding a blackish goo on the filters and nice clear solution. The pot and SS spoon are now discoloured.

On a good note, the solution, which is dropping perc as it cools tested negative for any chlorate.

 

What happened? Did I create a lot of sulfuric acid in the process?

 

Help!

[WSM]

For the chemists....WTF happened here??

 

I was doing a chemical clean using potassium mteabisulfite on a batch of raw (un-recrystallized ) k-perc. I dissolved 250g in 1.5l of water with 10g of K-meta added while cold in a SS pot. I think I had significant chlorate contamination in the perc. Anyway, it was still testing strongly (deep pink/red colour) for chlorate. I continued adding ~20% k-meta solution, about 25ml at a time for a total of 40g of k-meta. When I added the last 25ml or so, all the sudden, the solution turned blue/green and started to gently and "frothy" boil.

I neutralized the (greenish) solution with KOH to ph 8. There was a green/brown/black ppte in the water.

I then filtered through a stack of coffee filters, yeilding a blackish goo on the filters and nice clear solution. The pot and SS spoon are now discoloured.

On a good note, the solution, which is dropping perc as it cools tested negative for any chlorate.

 

What happened? Did I create a lot of sulfuric acid in the process?

 

Help!

 

Hi Bonny,

 

Just a thought. The stainless steel might be the culprit. I once made the mistake of putting ferric chloride solution in a cheap stainless bowl and after a while had a sieve ! The stainless was peppered with small holes; the solution ate the stainless steel!!! With SO2 and various species of sulfur-oxygen compounds it's not a stretch to think the stainless may have reacted with it. Stainless usually contains iron, nickel and chromium; and your green/brown/black precipitate may well contain some of these. Again, I'm not saying this did happen, but it's a possibility to consider.

[Bonny]

Hi Bonny,

 

Just a thought. The stainless steel might be the culprit. I once made the mistake of putting ferric chloride solution in a cheap stainless bowl and after a while had a sieve ! The stainless was peppered with small holes; the solution ate the stainless steel!!! With SO2 and various species of sulfur-oxygen compounds it's not a stretch to think the stainless may have reacted with it. Stainless usually contains iron, nickel and chromium; and your green/brown/black precipitate may well contain some of these. Again, I'm not saying this did happen, but it's a possibility to consider.

 

I'm not really sure what happened, but the change was almost instantaneous, from clear to blue/green. I tested the filtered solution today for chloride using silver nitrate, the sample almost turned to goo there was so much. Anyway, I discarded the batch as I don't really know what could be in there.

[pdfbq]

Hi all,

Again I have the same problem with the white stuff. Have an anode from Swede now and started all over but half way the first run already its pulling only 8A (After an initial of 25A)

I Know I'm half way because I have this density measuring system which tells me reasonably accurate where I am.

 

This time I did not use tap water but demineralized water.

The NaCl salt is consumer salt with 13 mg/kg E535/E536 additive (Natriumferrocyanide, Kaliumhexacyanoferraat (II))

I'm in Holland and if we will find Lead Dioxide in this salt we'll be front page!

I have about 600g of salt in my cell so not more than 8 mg of the additive.

 

 

Now suddenly I got this thought: Is it Silicon Dioxide?

When I look at your pictures I see no glass cells, only PVC etc. I have glass because I'm on NaCl and you don't need a big cell.

 

So question is: Could it be Silicon Dioxide? and could this stuck to the anode? and more important: How to remove it? (because rubbing is not working well)

 

Strange thing is that my platinum anodes do not have this issue. Apparently It it does not stick to platinum.

 

Damn...

Edited May 2, 2010 by pdfbq

[bikemaster]

I was running a 4 liters glass bottle cell for 8 months, and I never have this type of deposite. (It was soda glass)

[WSM]

Very cool! Being a sucker for a good deal, I snapped one of these up. I'll report on it's properties when it arrives. Swede, PM sent.

 

WSM

 

The power supply arrived today! The initial findings are: Size-5.25"x16"x19" including all attachments (handles, terminal strips, etc.). It has a 4" computer fan which runs a little loud but seems to cool well (high volume of moving air comes out cool, although I'm testing without a load, initially). There is a trimmer pot on the face of the unit (marked VA) which allows voltage output adjustment from 3.75Vdc to 6.13Vdc (initially it was set for 5.32Vdc; again, without a load). I need to set up a load and see what kind of amperage this baby can pump out!!! The output posts are 1/4-20 studs on the back of the unit near the fan.

 

Next to the VA trimmer is a trimmer marked CL which I'm hoping is a current adjust potentiometer. I haven't found any literature online yet but I haven't given up either. I'll see what else I can discover about this unit and edit this post to reflect what I learn. On the face of it, this unit looks to be a very good deal and a great chlorate workhorse. I'll update more later.

 

WSM

 

To those considering one of these units, Mine took exceptionally long to arrive due to a family tragedy with the seller. Once he got back home it came fairly fast and in good shape by UPS. If you have any questions, ask away. I'll do my best to answer.

Edited May 5, 2010 by WSM

[pdfbq]

I was running a 4 liters glass bottle cell for 8 months, and I never have this type of deposite. (It was soda glass)

Hia bikemaster. Did you use NaCl or KCl?

Did you use some form of ph control?

Edited May 6, 2010 by pdfbq

[bikemaster]

Cell spec:

 

6,65 V

4,5 Amp

Was running KCl to KClO3

Starting at saturated solution (dissole the more salt as possible in boilling water and let drop slowly the solution to the room temp)

One month by run. (I never calculate the Cl- content but I think I always stay high)

No ph control

MMO anode from northstar pyro (5cm X 15cm)

Stainless steel Cathode (really high grade : 5cm X 15cm X 1,1 mm)

 

Observation:

The electrolite turn to pale green after the month (cause by ss cathode)

The SS cathode turn black after time (I was brushing the cathode between every run and sometimes i was washing it with hot HCl)

The MMO have got some white deposite but it was easy to wash with the brush (never see I difference in the yeild cause of the white deposite, and it was really small even after one month)

[Bonny]

Cell spec:

 

6,65 V

4,5 Amp

Was running KCl to KClO3

Starting at saturated solution (dissole the more salt as possible in boilling water and let drop slowly the solution to the room temp)

One month by run. (I never calculate the Cl- content but I think I always stay high)

No ph control

MMO anode from northstar pyro (5cm X 15cm)

Stainless steel Cathode (really high grade : 5cm X 15cm X 1,1 mm)

 

Observation:

The electrolite turn to pale green after the month (cause by ss cathode)

The SS cathode turn black after time (I was brushing the cathode between every run and sometimes i was washing it with hot HCl)

The MMO have got some white deposite but it was easy to wash with the brush (never see I difference in the yeild cause of the white deposite, and it was really small even after one month)

 

My electrolyte (using a Ti cathode) also had a pale green colour- I think this is more from chlorine and/or hypochlorite- standard bleach has a similar colour

I got the white crap on the cathode mostly, maybe a tiny bit on the anode, but don't remember for sure.