making potassium (per) chlorate

[WarezWally]

Got a swanky gas mask now

[50AE]

I made a simple, small chlorate cell, using 2 graphite rods from D batteries as anodes and a steel rod as cathode. The voltage is 5V, the current ~2A, capacity 300mL. The problem is, the graphites errodes very fast. The first pair lasts 35 hours, but the second not even 24 hours, and the salt concentration is not below 10%. With these results, I have to use 10 graphites to make some grams of chlorate ?

 

And I can't find cheap anodes, like MMO. They are so expensive.

Edited February 27, 2009 by 50AE

[tentacles]

The battery type of graphite rods are not dense at all, and make lousy anodes - even graphite gouging rods are much better. That said, if you really want to make a bunch of chlorate, talk to Swede here about getting an anode made. It won't be expensive and it will last a long time. Tell him I sent you so he can cut my commision check ;P

 

If you can find some EDM graphite or other densely pressed type, it will last much longer than the cheap stuff. Other things that will help would be pH control, it will reduce the erosion drastically.

Edited February 27, 2009 by tentacles

[Bonny]

The battery type of graphite rods are not dense at all, and make lousy anodes - even graphite gouging rods are much better. That said, if you really want to make a bunch of chlorate, talk to Swede here about getting an anode made. It won't be expensive and it will last a long time. Tell him I sent you so he can cut my commision check ;P

 

If you can find some EDM graphite or other densely pressed type, it will last much longer than the cheap stuff. Other things that will help would be pH control, it will reduce the erosion drastically.

 

 

I think the best plan is to check the Agora here and get a nice anode from Swede. If you decide to continue with carbon/graphite anodes, they can apparently be treated with linseed oil to last longer. see here:

http://www.wfvisser.dds.nl/EN/chlorate_EN.html#thermal

[50AE]

Thanks, I will contact Swede.

 

About the pH control, I read that it must be kept acidic. Does the basic pH increases the errosion ?

[tentacles]

Actually you just want it slightly below neutral, pH 6.8 is pretty optimal. Basic pH increases graphite erosion by an incredible amount - dann over at sciencemadness is doing some pH controlled graphite cells lately, and it really makes a huge difference in efficiency and erosion. With the MMO anodes the pH control mostly only affects efficiency, but technically they will erode faster in a basic cell - you might lose 1/3 of it's life. MMO anodes will last at least 3 years making chlorate in pH controlled cells, so it's a pretty moot point for us.

[50AE]

I'm out of money this month, so no buying.

 

I have to buy a pH meter, there are cheap ones on eBay for 12-15 euro, (0-14)I hope they're good enough.

I'd like to know what is the easiest method to understand the chloride quantity in the electrolyte, to catch it when the concentration is below 10% ?

[Swede]

The cheap pH meters work, but remember that they need to be calibrated properly with buffer solutions, and especially, they need to be stored correctly. A good homemade storage solution is 3M potassium chloride. Keep the immersions fast, and to a minimum, in an active cell, and it is best to draw samples off and test those rather than dip into a working cell.

 

To measure chloride, you can titrate (PITA), use Hach chloride concentration strips, or simply do some math to predict when the chloride will be at 10%. It takes 161 ampere-hours of current at 100% efficiency to convert 1 mole of chloride into chlorate. To use this info, you first determine how many moles of chloride ion you have in your cell, keep track of ampere-hours, and determine how many AH it will take to reduce your chloride to 10%. Then, take a guess at your efficiency. If you guess 60% (a likely number), you divide your estimated AH by 0.6 to determine actual AH needed to take your cell to 10%. If it goes to 7 or 8%, no big deal. 1 or 2%, that is a big deal and will increase your erosion rate, and besides, efficiency nosedives as Cl- is diminished. That is one reason I like using potassium salts... you SEE the product as it is made and accumulates, and there comes a point where the production slows down dramatically; that is usually around 7 or 8% Cl- by weight.

 

It is possible to overly complicate this whole process, and I specialize in that!

 

If the goal is simply to make chlorate for pyrotechnics, I think the easiest way to do it is this, using MMO. Start with saturated KCl stock at 30 degrees C or so. Run the cell until the crystal fallout seems to definitely slow. Harvest and wash the crystals with ice water; dry them. Take the washwater and old liquor, and pour it into a poly container, the bottom of which is lined with KCl nuggets. Allow it to sit for a few days, or agitate if you want to hurry things along, and then decant the recharged liquor back into the cell. Repeat as needed. With potassium salts, there is no substitute for volume. 5 liters of KCl liquor will produce a kilogram of chlorate before it slows down.

[WarezWally]

Has anyone worked out what goes on in a perchlorate cell accurately? I tried to make sense of it and just gave up. One giant reaction soup, electrochemical cells were never my forte, to much going on for my untrained mind to fully understand Edited March 13, 2009 by WarezWally

[50AE]

Thank you Swede. The unknown for me was the efficiency of the cell, but I'll take it as 50-70%.

 

About the MMO anodes you sell, I have some questions :

-Will it erode faster if I deliver a big current ? Is there a limit of current per surface ?

-Will it erode faster if the temperature of the electrolyte exceeds a certain value ? If yes, what is it ?

-Are there other factors that can can reduce the anode's life ? Except for the electrolyte chloride solution <10%, for which I already know about.

[Swede]

50 AE, PM sent...

 

WW, I'm convinced it's smoke, mirrors, and basically the Pt saying to the chlorate, "Take up one more oxygen atom or I am going to kick your ass. That's a good boy, that wasn't so bad now, was it?"

Edited March 13, 2009 by Swede

[50AE]

Thanks to Swede for his titanium MMO plated anode and cathode...

 

I've obtained my first batch of KClO3 !

 

 

Sadly for you, I don't have pics of the processing, but only of the cell... for now. So I'll describe my method.

 

I used NaCl instead of KCl. I'm not able to find potassium chloride in Paris. But I have 300 grams of KNO3 which I'm not going to take with me, I have to throw them or give them to anyone, but there's no one . So why throwing them away, when I can use them ? KNO3 + NaClO3 -> KClO3 + NaNO3.

 

I guessed my cell efficiency at 50% and poured a saturated NaCl solution. I ran the cell for 48h on 5 volts and 7A. I stopped it, left the liquor cool and added the KNO3. Crystals started to rain . I harvested them, dried them, recrystallized and washed them again and obtained some 45 grams of KClO3 of acceptable purity.

 

http://img23.imageshack.us/img23/7014/dsc04477z.th.jpg http://img12.imageshack.us/img12/3006/dsc04478l.th.jpg

 

With some calculations, the cell efficiency was really ~50%. This was my test run. Now that I know how efficient the cell is, I can guess the run times.

 

Here are some more pics : The cell, electrodes and the power supply .

 

http://img11.imageshack.us/img11/7708/dsc04483p.th.jpg http://img10.imageshack.us/img10/152/dsc04484v.th.jpg http://img9.imageshack.us/img9/6148/dsc04485.th.jpg http://img25.imageshack.us/img25/1458/dsc04486k.th.jpg http://img6.imageshack.us/img6/6449/dsc04488qhy.th.jpg http://img22.imageshack.us/img22/8800/dsc04489i.th.jpg http://img4.imageshack.us/img4/1300/dsc04490b.th.jpg http://img206.imageshack.us/img206/430/dsc04493.th.jpg

 

And I uploaded a video of the deflagration of .5g of H3 composition

[Mumbles]

How do you judge "acceptable purity"?

[50AE]

I tested it for a green organic comp and the color was good. Not the best, but good.

 

I don't know for other impurities, I admit that. I only know that the pH is slightly alkaline

[Swede]

Mumbles, I think MMO-produced potassium chlorate produced from KCl, straight from the cell, well-washed, will do good pyrotechnic work as is, because the likely contaminant is KCl. Recrystallization would definitely improve things, but for a chlorate-based comp, I don't think it is necessary. This is all conjecture and opinion... I don't have the pyrotechnic experience to truly judge. The one test I did on freshly-harvested K-chlorate showed less than 1% impure, based upon the assumption that chloride is the impurity of interest.

 

I may be wrong; grain of salt and all that!

 

Sodium adds to the challenge, though. I think one reason I enjoy this as much as I do is the purification process for perchlorate. Today, I am going to try a side-by-side comparison of HCl reduction of chlorate remanants vs. potassium metabisulphite, all done on some crude perchlorate I harvested some time back. We'll see which works better and is easier.

Edited April 17, 2009 by Swede

[Ventsi]

50AE

I was using the same way to vent the gases produced by my cell but i found out its next to impossible with my cell smoking like a train.

 

I recomend you find any way possible to vent the gasses ie; a long garden hose ?

Anyway good luck with the KClO's!

 

PS; I thought you lived in BG ,did you move to Paris?

[50AE]

50AE

I was using the same way to vent the gases produced by my cell but i found out its next to impossible with my cell smoking like a train.

 

I recomend you find any way possible to vent the gasses ie; a long garden hose ?

Anyway good luck with the KClO's!

 

PS; I thought you lived in BG ,did you move to Paris?

 

Well, my cell isn't smoking much. But you're right, I got a longer hose somewhere, have to search for it.

 

I live in BG, I moved to Paris temporarily. Here I can't do any pyro at all. I'm hopefully returning to BG this summer, to resume my pyro activity

[Ventsi]

I was kidding with the *smoking* =].

 

Yeah Paris really is a great place I was there for a day when my flight to the US got delayed.

I'm off to buy some KCl and supplies and prepare for Easter tommorow!

[50AE]

A friend wants to sell me some cheap fertilizer grade KCl. He says it's a red powder, and the red stuff is insoluble. So I did some research and I found this

http://en.wikipedia.org/wiki/Sylvite

 

He seems to have the crude, true fertilizer grade of KCl. It is suitable to make KClO3 after purifying it ?

[Swede]

A friend wants to sell me some cheap fertilizer grade KCl. He says it's a red powder, and the red stuff is insoluble. So I did some research and I found this

http://en.wikipedia.org/wiki/Sylvite

 

He seems to have the crude, true fertilizer grade of KCl. It is suitable to make KClO3 after purifying it ?

 

I think to turn sodium to potassium chlorate, you'd be OK, but I wouldn't want to use it to start a potassium cell, due to the unknown impurities. By creating a saturated solution of this mineral, filtering the insolubles, then using it to replace the sodium, the stuff you want will precipitate, and hopefully everything else will remain dissolved. But loss of potentially recyclable chlorate, and the hassle of wondering just how much sodium is left in the product, was one of the reasons I wanted to start with potassium from day 1, despite the crappy solubilites. Every where I look (web pages), they all seem to say the same thing, basically only a fool starts with potassium chloride. I love it because I know what's in there. Low solubilities are easily overcome with raw cell volume.

 

Anyway, I suspect the sylvite will have a fairly major sodium contaminant, but that doesn't prevent it from being used in metathesis. Can you get a pound or so on a trial basis? Say something like "I'd like to test it before committing to a 50 kg sack." I can't believe he'd object.

 

I also can't believe there's not big sacks of "Muriate of Potash" at the garden stores in Europe! It's safe and a good potassium source for gardens. Weird.

[50AE]

I really don't want to use the double decomposition from sodium chlorate to potassium chlorate, because I doubt if I'll be able to clean the product from sodium contamination completely. I prefer starting from potassium chloride.

There is "murrate of potash", but the guy sells his chloride cheaply. And I don't really want a bulk quantity, like 50kgs.

[deadman]

You can get rather pure KCl from Home Depot, Lowes, or (insert hardware store here). Sold usually as water softener salt. I usually see it in 40 pound bags. Check the bag because it's sometimes sodium chloride. The sodium is usually 3-4 bucks a bag and the potassium bag is usually 8-11 bucks a bag.

[50AE]

In the local chemistry shops, there is :

 

KCl fertilizer grade - around 1 euro per kg and 40 euros for a 50kg bag. It's written "minimum potassium oxide - 60%"

KCl technical grade - they haven't put a price, I'll call them tomorrow.

KCl pure grade 99,5%- comes 4 euros per kg, which seems expensive

[Swede]

50AE, I know you're in Europe. Just as an example of what I start with, it's called "Diamond Crystal Potassium salt substitute" and it's for water softeners. The nuggets are off-white, and vary in size from peas to walnuts. There is a small amount of dirt and crud, which I used to filter off, but now I simply decant.

http://www.diamondcrystalsalt.com/Water-So...m-Chloride.aspx

 

40 lb or 18 kg for $14, $0.78 per kilo. It says 99.1% pure, and I'm sure beyond the bits of dirt it's sodium impurity. Still, it works. I'm going to guess that KCl fertilizer grade you mention is probably very similar. I'm not sure what they mean when they say minimum potassium oxide - 60%. I'll bet it's a decent and usable KCl. The other stuff is too expensive, as is table salt substitutes.

 

I applaud your notion of starting with KCl rather than NaCl. I think it is the way to go. You only have to stock one chloride salt, it's easy to process, and you don't need to do the labor of metathesis... you get to watch the chlorate form, and if a comp calls for chlorate, I think it is safe and effective to use as-is, no recrystallization.

 

Do they have those 50 kg bags out on display? There's usually a broken bag, and leaking nuggets. Can you investigate a couple of these nuggets? Not in the sense of using them in a cell, but just a general check of solubility and relative purity.

[50AE]

One guy has some of this KCl fertilizer stuff and he proposes me a deal, to give him 1 part of KClO3 for 2 parts of KCl. From 2 parts KCl, I will be able to make 3 parts of pure chlorate, 1 part goes to him.

So I get 2 parts KCl to 2 parts KClO3 for free.

Maybe I'll ask him to filter and recrystallize his stuff

 

I doubt I can really open 50kg bags, also they're not on display, they're hidden in a storage room and only workers of the shop have access to it.

For example, first I have to say what chemicals I want to buy and when I'm finished, a guy goes to the storage and gets them.

Edited July 13, 2009 by 50AE