making potassium (per) chlorate

[MrB]

I suspect that the price of a platinum electrode will deter most people.

I suspect your right. Thats where "cheap" alternatives come in. Lead dioxide over MMO, Titanium, or even plastic while not as longlived, makes for a lot smaller initial investment. The problem is, of course availability of "good quality" PbO2 anodes.

 

Hell, availability seams to be a problem all together, and thats before even adding the "good quality" criteria.

B!

[taiwanluthiers]

I made it to the US... so no point trying to make perc when people will sell those for 2 bucks a pound. Actually I won't be doing much pyro at all... so if I need perc at all it will only be a few hundred grams at most.

[WSM]

In MY opinion only,

KCl should give good potassium chlorate with ease, and it should be clean.

 

BUT for Kperc I'd start with NaCl make chlorate in one cell, then make perc in another cell with a platinum electrode giving the expensive electrode a safer set of cell conditions to reduce erosion.. Dump KCl in later to ppt the perc out seems easy. But I was a process chemist in a factory for years. I suspect that the price of a platinum electrode will deter most people.

 

After all these years, I'm seeing these proceedures as the best approach, too. There's a reason (several reasons, actually) industry does it this way, and I admit I have to agree. The exception is most of the chlor-alkalai industry goes from sodium chlorate to potassium chlorate, and I like the simplicity of going directly from KCl to KClO₃, and we can thank the availability of MMO for that. Now, if we could only find an equally strong anode to go from chlorate to perchlorate as easily and cheaply as MMO does for making chlorate.

 

One difference between us is I'm investigating both platinum and lead dioxide for the perchlorate process, and I'm still hoping to find something better later on. I'll try to share here what I learn in the process.

 

WSM

Edited December 10, 2014 by WSM

[WSM]

I made it to the US... so no point trying to make perc when people will sell those for 2 bucks a pound. Actually I won't be doing much pyro at all... so if I need perc at all it will only be a few hundred grams at most.

 

If someone is selling potassium perchlorate for $2/pound (and it's good material), you should buy a couple drums and store them for future use! I doubt you'll see it that cheap again.

 

WSM

[taiwanluthiers]

I know CaliforniaPyro was selling it at 4 bucks a pound, and according to one friend it's expensive (perhaps to him since he buys it by the drums). Skylighter sells it at 11 dollars a pound, but their prices tend to be on the high side unless you catch their promotions/deals.

 

Even skylighter prices is a bargain to me for what I used to pay for perc. Some pays even higher (like over 40/pound).

 

I am not sure how true this is but you could heat chlorate to near its melting point (which I must remind that is very dangerous, just watch the molten chlorate/gummy bear experiment) for a period of time, and the chlorate turns into perchlorate. Although the yield is not that good and it's just plain dangerous... you also have to carefully control its temperature. Has anyone tried doing a small quantity of that?

 

As for water softening salts... only ones available in Taiwan were sodium chloride but in the US I found potassium chloride water softening salts at Stater Bros. It was about 20 dollars for a 20 pound bag, lot more expensive than the sodium chloride version but still lots cheaper than I could get in Taiwan and without the red crap to filter out.

[schroedinger]

I made it to the US... so no point trying to make perc when people will sell those for 2 bucks a pound. Actually I won't be doing much pyro at all... so if I need perc at all it will only be a few hundred grams at most.

God to hear that you made it and are fine.

At that price i would straight take half a ton and don't bother about making it myself. But here it is about 3 to 4 times that price.

 

@Arthur if you read swedes work, there where some god reasons to go straight from KCl to perc, mainly it was prof of concept.

 

And the anodes aren't that hard to make, and if you can buy industrial ones they cost about 25 $.

I now tried a couple plating baths and the best results i got from a bath containing out of lead nitrate, copper nitrate and nickel nitrate and triton X 100.

 

Also i added some lead carbonate to neutralize nitric acid which got set free, but at the end near to nothing was gone.

The reason behind this mixture is to neutralize the nitrous acid set free during plating as it oxidizes the sulfanic acid.

[Arthur]

I understand that Swede wanted to go straight from chloride to perc, one bath and no sodium contamination, BUT he didn't get a successful product. He got chlorate down to a fine art, but little perc.

 

Reading Schumaker's paper (linked above) the process using sodium chloride is commercially viable, leaving you able to add KCl or NH4Cl at the end to ppt out a useful salt.

 

I like the idea of high concentration chloride making high conc chlorate meaning that there is a lot of chlorate to use without giving a Pt electrode a hard time. Remember that all the sodium and some of the chloride is recycled into the chlorate cell.

[WSM]

I understand that Swede wanted to go straight from chloride to perc, one bath and no sodium contamination, BUT he didn't get a successful product. He got chlorate down to a fine art, but little perc.

Reading Schumaker's paper (linked above) the process using sodium chloride is commercially viable, leaving you able to add KCl or NH4Cl at the end to ppt out a useful salt.

I like the idea of high concentration chloride making high conc chlorate meaning that there is a lot of chlorate to use without giving a Pt electrode a hard time. Remember that all the sodium and some of the chloride is recycled into the chlorate cell.

 

I believe nearly all the chloride is recycled as per the reaction:

 

KCl + NaClO₄ -> KClO₄ + NaCl, where the perchlorate drops out and the chloride is recycled to the chlorate process.

 

If you meant to say chlorine, then I agree.

 

I also agree regarding using high concentration chloride solution for the chlorate process AND high concentration chlorate solution for the perchlorate process. These would be the most efficient plus, I believe, easier on the anodes.

 

As for the LD plating process, I havent tried it yet so I can't comment on whether it's easy or not. I've been fortunate that through patience and careful searches, I've acquired six; two of one type and four of another, for a reasonable total price. I hope to test one of them before much longer, but my work schedule is very heavy and I'm taking a trip to visit family soon, so the first of the year may well be as soon as I can manage it.

 

WSM

[MrB]

For those that understands things better then i do, is this an interesting read? I'm guessing there is nothing new here, it's a paper from 2009, but since someone dropped it on a Swedish forum, i thought i'd link it here, so those with a better understanding then i have, can have a look at it.

 

B!

[Arthur]

"Remember that all the sodium and some of the chloride is recycled ....."

 

Intended to say that if you make chlorate then Na perc, then Kperc by precipitation , any chlorate not reacted to perc, and all the sodium and any residual chloride will get stored and returned to the chlorate cell. so nothing from the electrolysis should go missing.

[WSM]

For those that understands things better then i do, is this an interesting read? I'm guessing there is nothing new here, it's a paper from 2009, but since someone dropped it on a Swedish forum, i thought i'd link it here, so those with a better understanding then i have, can have a look at it.

B!

 

Yes. It correlates with a couple doctoral thesis' I have copies of (also of Swedish origin and printed in english, as it so happens). Thanks for sharing, B.

 

WSM

[WSM]

"Remember that all the sodium and some of the chloride is recycled ....."

Intended to say that if you make chlorate then Na perc, then Kperc by precipitation , any chlorate not reacted to perc, and all the sodium and any residual chloride will get stored and returned to the chlorate cell. so nothing from the electrolysis should go missing.

 

If I understand this correctly, you're referring to a one tank system to go from chloride to perchlorate? It seems in such a system, any leftover sodium chlorate in the mix with sodium perchlorate would also drop out when potassium chloride is added, making potassium perchlorate contaminated with potassium chlorate.

 

In a separate system, first sodium chlorate is made from the chloride (and purified by some means to exclude chloride from the next step). Second, sodium perchlorate is made from the purified chlorate. Now residual chlorate is destroyed with SO₂ so the sodium perchlorate is chlorate-free. Next it's exchanged with potassium chloride to form potassium perchlorate (which drops out of solution) and sodium chloride which is recycled to the original chloride-to-chlorate cell.

 

Yes, there are losses; but a purer end product is the result. A fair trade-off in my view.

 

WSM

Edited December 18, 2014 by WSM

[Arthur]

The way I read the Schumacher paper they made neo saturated brine, the first cell turned it to 600grams/litre of chlorate with some chloride, and this went into the second cell and afterwards a calculated amount of KCl was added to just precipitate all the perc, The perc was then separated and dried, while the rest was returned to a chlorate cell feedstock.

[Mumbles]

It depends on how you do it. If you have a good idea of the perchlorate concentration, you can easily add a calculated amount of KCl. The perchlorate will be the only thing precipitating out as you all the KCl. Once you totally precipitate the perchlorate, then any additional KCl will start then crashing out chlorate.

 

It seems weird to think about, but if you mix potassium chlorate and sodium perchlorate, it will make potassium perchlorate via the relatively small difference in solubility.

[Arthur]

Another thought;

Take hot saturated brine (NaCl) electrolyse it to say 80% completion, draw off lots of the liquid, and put it into a cell with perc anodes electrolyse it near to completion, then add to KCl calculated to be just insufficient. You should PPT out KPerc and send all the rest back to the chlorate cell feed stock.

 

OR;

take a small cell with MMO electrode fill it electrolyse it and add HCl (Swede's calculation based on amp hours). An Iwaki bellows pump would take 10% HCl, and a separate one would take a small flow rate of hot saturated NaCl both pulsing under control. This would then send chlorate loaded solution to a tank with PbO2 or Pt electrodes and this would mean that with a suitable flow rate and current a strong solution of NaPerc with some NaChlorate would come out of the end slowly. Add KCl to this and KPerc should drop out, all the rest being recycled into the brine feed stock. (another Iwaki pump?)

[pyrojig]

 

It seems weird to think about, but if you mix potassium chlorate and sodium perchlorate, it will make potassium perchlorate via the relatively small difference in solubility.

 

This is a interesting approach. It may find favor with folks that have a large stock in Kclo3 and wish to get KP , as well as recycle the Naclo3 into a perch cell to be run back into a perch. This would make kcl or Nacl impurities practically nonexistent. One would just have to kill any residual chlorate in the double decomp process via meta-bisulfate

[WSM]

It depends on how you do it. (1)If you have a good idea of the perchlorate concentration, you can easily add a calculated amount of KCl. The perchlorate will be the only thing precipitating out as you all the KCl. Once you totally precipitate the perchlorate, then any additional KCl will start then crashing out chlorate.

 

It seems weird to think about, but (2)if you mix potassium chlorate and sodium perchlorate, it will make potassium perchlorate via the relatively small difference in solubility.

 

1) This would be easy if a reliable method of accurate perchlorate concentration were available to us. I'm interested to know if such a measurement method is out there. Any thoughts?

 

2) An interesting thought. I like the idea and wonder about it's practicality. If chlorides can be eliminated from the perchlorate cell, a major cause of anode degradation will be eliminated.

 

This bears furthur investigation...

 

WSM

[WSM]

 

This is a interesting approach. It may find favor with folks that have a large stock in Kclo3 and wish to get KP , as well as recycle the Naclo3 into a perch cell to be run back into a perch. This would make kcl or Nacl impurities practically nonexistent. One would just have to kill any residual chlorate in the double decomp process via meta-bisulfate

 

Yes, but the desired product to destroy chlorate is SO₂ (which the bisulfite provides), if I understand the process correctly.

 

I believe Swede once mentioned using potassium metabisulfite with the potassium perchlorate, to destroy any residual potassium chlorate.

 

I like the idea of destroying residual sodium chlorate in the sodium perchlorate with sodium metabisulfite, before adding potassium chloride to form potassium perchlorate (to make chlorate-free potassium perchlorate). This makes the most sense to me, from a practical standpoint.

 

WSM

[WSM]

Another thought;

Take hot saturated brine (NaCl) electrolyse it to say 80% completion, draw off lots of the liquid, and put it into a cell with perc anodes electrolyse it near to completion, then add to KCl calculated to be just insufficient. You should PPT out KPerc and send all the rest back to the chlorate cell feed stock.

 

OR;

take a small cell with MMO electrode fill it electrolyse it and add HCl (Swede's calculation based on amp hours). An Iwaki bellows pump would take 10% HCl, and a separate one would take a small flow rate of hot saturated NaCl both pulsing under control. This would then send chlorate loaded solution to a tank with PbO2 or Pt electrodes and this would mean that with a suitable flow rate and current a strong solution of NaPerc with some NaChlorate would come out of the end slowly. Add KCl to this and KPerc should drop out, all the rest being recycled into the brine feed stock. (another Iwaki pump?)

 

The only problems I see with the suggestions are: 1) system complexity and a major challenge balancing or regulating everything for efficiency. 2) creating such a system where chlorides are eliminated, which tend to seriously degrade the perchlorate anodes (platinum or lead dioxide, anyway).

 

Interesting thoughts, though.

 

At Arthur's suggestion (a couple years ago), I looked into and purchased several Iwaki pumps on eBay (both bellows type and magnetically-coupled), which were salvaged from photo finishing equipment. They are excellent fluid moving devices and built to handle many types of corrosive liquids safely, as well as being able to be serviced if damaged or worn out. I was most impressed with the Iwaki magnetically-coupled chemical handling pumps, which I've used to dissolve course KCl crystals by recycling distilled water through them in a PVC tank. This sped up the electrolyte preparation process for me in a dramatic way. They are also very efficient, electrically (low power consumption).

 

Thanks, Arthur.

 

WSM

Edited January 12, 2015 by WSM

[pyrojig]

Thank you for the clearing up on the "Na perch "using Na-bisulfate as a first step, before Kcl03 is exchanged in sol. to get the desired "clean KP".

Glad your back home safe . Looking forward to the new postings and progress.

[Arthur]

I worked in the photo lab industry for twenty years and the Iwaki bellows pumps handled things from 50% sulphuric acid to strong sodium hydroxide solution. If you run the pumps for a few seconds every minute you get a steady volume of chemical pumped, then you can adjust the volume per stroke so that you can get from 1ml to 100ml per stroke using selected sizes of bellows.

 

For pH control I'd like to have a bellows pump adding HCl at say 10% and with the control set to be just less than stoichemetric so that say 12 hourly pH paper checks just need a little extra HCL to be added to keep the pH steady (it's HARD to remove HCL so don't add too much).

[WSM]

Thank you for the clearing up on the "Na perch "using Na-bisulfate as a first step, before Kcl03 is exchanged in sol. to get the desired "clean KP".

Glad your back home safe . Looking forward to the new postings and progress.

 

Thanks, pyrojig. I'm glad to be home and back at it. Thanks for your help and support with several of my projects, too. A lot of this would be much tougher without networking.

 

One thing, though; when describing what we're doing and using, let's be accurate. You've been describing the chlorate cleanup process using a bisulfate (NaHSO₄), and I've been talking about using a bisulfite (NaHSO₃). I'm sure sodium metabisulfite breaks down to produce the SO₂ neccessary to destroy unwanted chlorate, but does sodium bisulfate do the same thing?

 

After a Wiki search, I think I'm half right about this. The bisulfite will work, but sodium metabisulfite (Na₂S₂O₅) should work better, by giving off more SO₂, if I understand this correctly. I don't believe the bisulfate is the right material for the job.

 

WSM

[WSM]

I worked in the photo lab industry for twenty years and the Iwaki bellows pumps handled things from 50% sulphuric acid to strong sodium hydroxide solution. If you run the pumps for a few seconds every minute you get a steady volume of chemical pumped, then you can adjust the volume per stroke so that you can get from 1ml to 100ml per stroke using selected sizes of bellows.

 

For pH control I'd like to have a bellows pump adding HCl at say 10% and with the control set to be just less than stoichemetric so that say 12 hourly pH paper checks just need a little extra HCL to be added to keep the pH steady (it's HARD to remove HCL so don't add too much).

 

Some interesting thoughts, but on the face of it I'd be very concerned about overdosing the system with HCl (unless a very large system is what we're describing). Most amateur systems are typically on the small side, 20 liters (5 gallons) being on the larger side of things.

 

As for neutralizing an overdose of HCl, in a sodium system NaOH would handle it, but watch quantities and concentrations. By the same thought, I suppose KOH would do the same for a potassium system. All this in the chlorate half of a dual setup (first chlorate, second perchlorate), would probably work okay. In the second half, too much chloride would be a problem for typical perchlorate anodes (Pt or LD).

 

WSM

[Arthur]

The reason I like the bellows pumps for acid addition is that they can be adjusted down to about 0,5 ml per stroke so it should be easy to add say 0.5ml every 15 minutes by a simple timer relay or by something more programmable. You could even use Swede's figures for acid per amphour and measure the current and add the right amount of acid automatically

[WSM]

The reason I like the bellows pumps for acid addition is that they can be adjusted down to about 0,5 ml per stroke so it should be easy to add say 0.5ml every 15 minutes by a simple timer relay or by something more programmable. You could even use Swede's figures for acid per amphour and measure the current and add the right amount of acid automatically

 

I like the idea of using an amp/hour controller, but personally I like Swede's use of a gravity fed, solenoid controlled Teflon valve combined with a Teflon needle valve. Such a system adds the dilute acid as a stream to the acid injection diffuser tube in the cell, rather than by pulses as the bellows pump does.

 

Pulses aren't bad, though. My home made diaphragm pumps also pulse and the duration and frequency of the pulses are directly controlled by the timer circuit I use. Also, parastaltic pumps pulse as they operate.

 

Does anyone have a good circuit design for an amp/hour controller?

 

WSM