making potassium (per) chlorate

[taiwanluthiers]

I know its somewhere in the thread but I just like to confirm something.

 

So I use MMO to make chlorate (sodium or potassium), then once most of the chloride has become chlorate, I would remove all residual chloride and then put them in a separate perchlorate cell with Platinized Titanium anode?

 

So when making sodium perchlorate, how do I remove the sodium chlorate mother liquor of all chloride? I read boil the solution (which I am sure will use an untold amount of heat) until crystals form, then cool to near freezing and filter out the crystals. Do I dump the crystal or keep the crystal (as in what precipitates out, chloride or chlorate?)

 

Silver nitrate is very expensive, so would lead nitrate be a good test for chloride level?

[pdfbq]

@Swede. I knew you had them . I have seen some pictures of them, can't remember where exactly though.

 

4" x 8" means big current. I have 2" x 5" and made easy 20A over 5.2V.

 

Taiwanh. You keep the krystals.

You boil down about 25%. thats no big deal.

Edited October 11, 2012 by pdfbq

[taiwanluthiers]

I take it you can't use steel or stainless steel pots to boil this either. So what else can we use, ceramic or glass?

 

You can't exactly boil stuff with HDPE.

Edited October 12, 2012 by taiwanluthiers

[Mumbles]

Glass is ideal. Not everyone has 22L boiling flasks though. What would make you think that steel and SS are out of contention?

[athlon]

I tried with a SS pot first time and it rusted pretty badly, had to throw the pot away! Now I use a oven safe glass baking dish instead.

[taiwanluthiers]

Well, from previous posts people have said they've destroyed their SS pot from boiling chlorate solutions, which isn't really something I want since SS pot isn't exactly cheap. Ti pots would have been ideal but Ti isn't a good heat conductor meaning poor efficiency, and also Ti cookware is expensive.

 

I guess I'll just get a large Pyrex beaker for this...

 

I guess I can stick a heating element inside the solution in its cell container but the heating element would corrode (and leech copper into the solution) unless it was also made of Ti.

[frank]

There are many types of stainless steel.

The large heat resistant cooking bowls work OK if the heat source is not too severe. Don't put

a naked flame to them. If you get a suitable sized container and put some sand in it, about an inch

deep, put the bowl into the sand and heat the whole lot. This gives some buffering between the

bowl and heat source. You can wrap some insulation arount the outside container if you wish to

keep heat from escaping.

Believe it or not glass does etch a bit when you boil chlorate solutions.

 

Try this (I have not tried it).

Get a teflon sheet, you can get them as oven ware. You need the non porous type.

Line a cheap steel pot with it and go from there.

 

Once you have taken the chloride level to low levels (Chlorate cell), aroutn 60 grams per liter Chloride

only Chlorate will crystallize out as you boil off approx. half the volume.

 

Frank

[taiwanluthiers]

Would those mesh that has ceramic like substance coated in the center of the mesh, sold at lab supply stores work? Those seem to be designed for heating beakers with a bunsen burner, not sure what its called.

 

I am sure some type of stainless steel would work, but I would have absolutely no way of knowing which one works. I imagine it probably takes a lot of energy to burn off half the volume of a 22 liter solution... Do they do this commercially?

[taiwanluthiers]

Oh I have an idea... what if I place the sodium chlorate solution inside a microwave safe container (which will most likely be HDPE or PVC) and just boil them by placing it in a microwave?

[Arthur]

Has anyone measured the SG of a chlorate cell from fresh chloride through running to completion?

[pdfbq]

If SG means what I thinkn it means I did it with NaCl. I started at ~1.195 and ended at ~1.325 while topping with water only. No perchlorate formed then but I think its on the edge.

When going the NaCl route perc is not what you want at this stage I believe because you can not get it out of solution.

Edited October 15, 2012 by pdfbq

[WSM]

I was describing to Swede the prototype submersable diaphragm pump I built (pictured below):

 

 

The pump is made from PVDF plastic and Viton rubber so it's completely compatible with the cell fluids and is powered by an aquarium pump. I use a timer circuit built from a kit with adjustable settings for the pulse width and duration, to control an air diverter so the diaphragm can "breathe" in and out, drawing the fluid in and pumping it out using the two check valves on the top. The photos show the black Viton rubber sheet on the bottom (the diaphragm) and the gasket on the top with PVDF bolts holding it all sandwiched together. The whole assembly is denser than the liquor so it'll sink to the bottom naturally (even with air filling the diaphragm during operation).

 

The two check valves are held in PVDF compression fittings after turning one of the barbs down to straight tubes to fit (done carefully on a lathe) on each of the check valves (one pointing in and the other pointing out).

 

This is how I plan to pump the depleted liquor from the crystallizer to the RC. The diaphragm pump is located in a "heat well" in the crystallizer, hopefully keeping things warm enough that the devices there won't suffer from crystal fouling.

 

I decided to make the submersible pump so I wouldn't have to worry about external pumps jamming with crystals because of the temperature differences.

 

The whole deal runs on about 3 Watts of power, so it's very cost effective.

 

WSM

Edited October 16, 2012 by WSM

[WSM]

I was also describing to Swede how I configured the electrodes in the pickle-jar cell experiment I ran in July, 2011 and decided to show photographs of the arrangement here. The electrodes were made from scraps of MMO mesh and some scrap CP titanium plate I pounded flat from a failed cathode design.

 

 

What they lack in beauty, they make up for in utility. The test succeeded as well as I had hoped and proved many of the theories correct.

 

1) By surrounding the anode with close-fitting cathode plates, I was able to maximize the output of the cell, even with only one lead for both cathode plates.

2) I designed the cell to demand no more than 80% of the power supply's capacity so the supply got no more than slightly warm, even without a fan.

3) The filled, tubular electrode leads got warm, but not enough to cause the plastic compression fittings any trouble.

4) I drilled and tapped the PVC pipe cap used for a cell lid with NPT (National Pipe Taper) threads to accomodate the PVDF compression fittings and barb fittings used for accessories (electrode leads, hydrogen vent and air tube inlet for stirring the electrolyte).

5) Rather than use a stud to hold the leads, I elected to tap the top of the leads and bolt the electrical leads with a stainless-steel screw and two stainless washers. It worked very well.

 

The whole thing worked so well that the run only lasted for about 36 hours before the current dropped to about 50% and I pulled the plug. The cell got to 55^oC and stayed there for the duration of the run. The cell was roughly 3 liters in volume.

 

I should try it again, but with pH control added and see the difference.

 

WSM

Edited October 16, 2012 by WSM

[gregkdc1]

I have been reading about making chlorates and perchlorates for quite a while now. I have read pretty much everything on this forum as well as Dan’s site and most of what I could find on science madness some times more than once and feel like I am ready to take the plunge.

 

The type of anode that I want to make is a ceramic substrate lead dioxide anode, the idea that the anode will basically be similar to a massive lead dioxide anode with the added strength of the ceramic substrate. I know this anode has been tried and the problems of using a porous media substrate, more on that later.

For the ceramic I will use basic low temp clay and fire it in my micro kiln and the anode will have a rectangular shape to make it easier to connect to the electrode. One area I would like some pointers on is how to get the lead dioxide really deep into the pores of the ceramic. I figure if the lead dioxide is deep into the pours that this would give the strongest possible mechanical connection between the two materials. Would it help to rotate the anode while it is being plated? Also would it be better while making the ceramic conductive to use the method of nitrate oxidation versus rubbing the lead dioxide into the ceramic, remember I want to get it really deep into the pores?

As for the anode wicking up salts and ruining your electrical connection I plan on making a magnetite anode as a go between to the electrical connection. Obviously this maybe an issue getting a good connection and one of the reasons why I want a square anode to get a large contact surface area between the magnetite and lead dioxide. Last if the above mentioned anode doesn’t work would it be possible to fill the holes in a porous substrate anode with wax or linseed oil like when sealing graphite anodes under vacuum so the salts don’t wick up the anode? That way you could simply use silver metal to connect directly to the anode without the magnetite. Obviously if you used wax you would have to keep the cell temp lower than the melting point of the wax. Any thought or criticism for things I should look out for. It's too late for me the bug has already bitten.

Edited October 16, 2012 by gregkdc1

[WSM]

I have been reading about making chlorates and perchlorates for quite a while now. I have read pretty much everything on this forum as well as Dan's site and most of what I could find on science madness some times more than once and feel like I am ready to take the plunge.

 

The type of anode that I want to make is a ceramic substrate lead dioxide anode, the idea that the anode will basically be similar to a massive lead dioxide anode with the added strength of the ceramic substrate. I know this anode has been tried and the problems of using a porous media substrate, more on that later.

For the ceramic I will use basic low temp clay and fire it in my micro kiln and the anode will have a rectangular shape to make it easier to connect to the electrode. One area I would like some pointers on is how to get the lead dioxide really deep into the pores of the ceramic. I figure if the lead dioxide is deep into the pours that this would give the strongest possible mechanical connection between the two materials. Would it help to rotate the anode while it is being plated? Also would it be better while making the ceramic conductive to use the method of nitrate oxidation versus rubbing the lead dioxide into the ceramic, remember I want to get it really deep into the pores?

As for the anode wicking up salts and ruining your electrical connection I plan on making a magnetite anode as a go between to the electrical connection. Obviously this maybe an issue getting a good connection and one of the reasons why I want a square anode to get a large contact surface area between the magnetite and lead dioxide. Last if the above mentioned anode doesn't work would it be possible to fill the holes in a porous substrate anode with wax or linseed oil like when sealing graphite anodes under vacuum so the salts don't wick up the anode? That way you could simply use silver metal to connect directly to the anode without the magnetite. Obviously if you used wax you would have to keep the cell temp lower than the melting point of the wax. Any thought or criticism for things I should look out for. It's too late for me the bug has already bitten.

 

Hi Greg,

 

Did you get a chance to read Swede's blogs? He describes plating LD on an MMO anode, which I think may make a stronger foundation than the ceramic base. Plus being conductive is a real plus, also. I might also stress to be certain the LD you put on the electrode is the hard, crystalline beta form rather than the porous alpha form.

 

Good luck with your project, and please share your experiences with us here.

 

WSM

Edited October 16, 2012 by WSM

[WSM]

I don't remember if I mentioned WHAT I filled the round titanium tubular leads with. I think almost any soft solder would work but I chose 1/8" diameter, solid lead-free, silver bearing solder. The solder is roughly 95% tin, which is almost five times more conductive than titanium. The solder fill was introduced directly while heating the outside of the tubing with a propane torch.

 

WSM

Edited October 16, 2012 by WSM

[Swede]

I'll tale peoples' word for it that boiling chlorate in SS is a bad idea, but I was referring to the purification of crude PERchlorate.

 

I don't believe recrystallization of KClO3 is necessary. Chlorate crystallizes into hefty xtals, lending itself well to effective washing. If you don't stint on the washing during harvest, the crude electrolytic chlorate is (purely IMO) ready to go, once washed and thoroughly dried. The drying is important because there are volatiles that will evaporate and clean up the crystals even more. For example, freshly-washed crude KClO3 still smells a bit of bleach, but this goes away fairly quickly as the hypochlorite decomposes into KCl and KClO3. The less "bleachy" your chlorate smells when you spread it to dry the less KCl you will ultimately end up with.

 

Crude electrolytic KClO3 overwhelmingly consists of the chlorate, with minor impurities of KCl and perhaps a few other chlorinated species that are generally short-lived.

 

I remember doing a quantitative test for chloride on crude chlorate, and the quantity was very low. I don't think it would be a problem for perchlorate anodes. Of course, one could simply dissolve all the chlorate, dump in a handful of silver nitrate, filter the insoluble silver chloride out, and have a guaranteed chloride-free electrolyte... but who can afford that?

 

I would NOT simply transfer chlorate slurry directly from one cell into a perchlorate cell... I'd give it a good harvest procedure with an emphasis on the wash and dry.

 

I think washed, crude PERchlorate won't be overly harmful to stainless. The ideal purification procedure might include collection of the electrolytic perchlorate, and some form of washing that might include metabisulfite to scavenge and convert chlorate. Remember, KClO4 solubility is so poor, that chlorate should be easily washed away, and crystals by nature are pure. There are no hidden pockets of nastiness hidden away inside the xtals.

 

The worst case scenario for perchlorate would involve recrystallization, and for the amateur, interested in bulk production, that would suck quite a bit. But I'm hopeful that it can be avoided.

 

Edit: Taiwanluthiers - I missed the fact that you were discussing a sodium process. What you described is one of the main reasons I start with potassium. That, and the fact that in the end, you STILL have to use large amounts of potassium chloride to convert the product. Good luck in separating the chloride from the chlorate in a sodium chlorate electrolyte, and I don't mean that in a bad way... lot's of guys use sodium and make it work.

Edited October 16, 2012 by Swede

[Swede]

Has anyone measured the SG of a chlorate cell from fresh chloride through running to completion?

 

I tried it once, Arthur, but since I use potassium, the moment I withdraw a simple, I get massive crystallization as the sample cools.

 

If the idea is to use SG to determine where in the process you are, I think it's a good idea if it can be made to work, and it's accurate enough

[Swede]

WSM, your submersible pump is a thing of beauty, and the good part is that such a pump doens't need to have a huge flow. Slow is just fine, unless you are looking to transfer 100+ liters. Have you given it a test yet? It might be interesting to try it with a saturated, hot chlorate solution, start the pump, then let the system cool slowly to force xtallization to see if there are any problematic areas in its operation.

 

I also really like your elegant folded cathode and anode arrangement. It's going to have a super-low potential. I think the only thing that gives me a bit of pause is the spacing w/regards to chlorate xtals. Through most of a run, the concentration of chlorate is going to be too low to cause problems, and the temperature in the electrode area is going to be much higher than the rest of the cell, so it should remain xtal free through most of the run. Did you have any problems with the electrode system jamming with xtals?

 

@gregkdc: Rotation of the anode is (I think) important in getting a good, even coating of lead dioxide. Another thing that heps with the deposition is a vibration in the bath. Gas bubbles tend to form, preventing plating and making a weak coating.

 

I set up my lead dioxide plating rig both with rotation and vibration, and I think they helped. The rotational part is a bit tricky because you have to set up a carbon brush or something similar to deliver the current to the anode. Have you read "Lead Dioxide Plating for dummies"?

 

I think there's a lot to be said for a ceramic substrate IF you can get it to conduct well. I know little about ceramics... might it be possible to incorporate graphite powder into the slip or clay to at least give it a bit of a head start? I'd make the surface extremely coarse or rough, and perhaps poke a few dozen holes in it, to make it look like a cracker.

 

Something else - if you use a titanium leader to the ceramic, the Ti will accept lead dioxide, but it will flake off quickly, possibly opening the connection between the leader and the bulk of the PbO2 on the anode.

 

This area of amateur research is still wide open, and I encourage you to give it a shot. When I do t again, my plan is to use a thin Ti sheet, drill dozens of small holes in it, coat that with MMO, verify the MMO coating is secure and conductive, and then coat THAT with PbO2. The goal would be to have the PbO2 plate both sides and also plate the holes through, so that there is a mechanical PbO2 connection between both sides of the anode.

[Swede]

I don't know if you guys remember the "Length of run Worksheet" I posted a while back. It was the "tax form" that allows one to simply determine how long to run a chlorate cell. I created another (similar) form, Current Efficiency Worksheet for KClO3 electrolysis based upon wet and dry mass, and bundled the two. This form calculates the current efficiency of your cell, based upon both the dry yield, and the probably mass of the still aqueous KClO3.

 

Done purely for fun... hopefully someone will find it useful. It's on page two of this PDF file. Download here.

 

 

Current Efficiency Worksheet for KClO3 electrolysis based upon

wet and dry mass

Note: with certain lines, an example (in parentheses) is provided.

1) Mass of your dry KClO3 in grams (3,550) M = ________

2) Volume of your cell (V) in liters (25) V = ________

3) Temperature of electrolyte AFTER cooling, and

separation of your main solid yield (20) T = ________

4) Enter the chart below at T on the X axis. Enter

the value of grams per 100ml water KClO3 (7) ________

5) Multiply line 4 by 10 (70) ________

6) Multiply line 2 and line 5 (1,750) Wet Yield = ________

7) Add line 1 to line 6 (5,300) Total Yield = ________

8) Ampere-Hours for the run? (8,725) AH = ________

9) Multiply line 7 by 131.22 (695,466) ________

10) Result: Divide line 9 by line 8 (79.7) CE = ________

Edited October 16, 2012 by Swede

[WSM]

WSM, your submersible pump is a thing of beauty, and the good part is that such a pump doens't need to have a huge flow. Slow is just fine, unless you are looking to transfer 100+ liters. Have you given it a test yet? It might be interesting to try it with a saturated, hot chlorate solution, start the pump, then let the system cool slowly to force xtallization to see if there are any problematic areas in its operation.

I also really like your elegant folded cathode and anode arrangement. It's going to have a super-low potential. I think the only thing that gives me a bit of pause is the spacing w/regards to chlorate xtals. Through most of a run, the concentration of chlorate is going to be too low to cause problems, and the temperature in the electrode area is going to be much higher than the rest of the cell, so it should remain xtal free through most of the run. Did you have any problems with the electrode system jamming with xtals?

 

Thank you for the kind words regarding the submersible diaphragm pump. The pump I showed is a working prototype; my original design uses two solid blocks of Kynar, bolted together with PVDF or PTFE bolts after milling a diaphragm expansion chamber into one of the two blocks. I've built working diaphragm pumps made of PVC and they work fine, but this one is the first I've built of compatible materials to be used inside the cell and in the liquor. One possible problem is pumping cold air into a warm pump. If it appears to be a problem, I may have to develop a scheme to preheat the air. We'll see...

 

If I need to move large volumes of electrolyte, I'll use a different system.

 

I have a friend who used the diaphragm pump on it's side and it suffered crystal fouling. He discovered it works better when aligned flat, the way my prototype is built. His continuous system works fine using a similar pump the way I intend to use one of mine (except mine is designed to be inside the system to avoid temperature differential problems).

 

The electrode design is one I dreamed up several years before, and developed as I built it up from the materials I had on hand. I have an untried prototype (of a somewhat similar design) I built about four years ago and never got around to testing.

 

I never had any crystal jamming problems when I ran my system a year ago in July, but it was an initial run using KCl solution and not recharged electrolyte. If I recharge it and run it again, we'll see if it runs fine without jamming. It's so active and warm when it runs, I doubt it'll have crystal jamming problems (of course if it does, we'll find some way to solve the problem... ).

 

WSM

[WSM]

I don't know if you guys remember the "Length of run Worksheet" I posted a while back. It was the "tax form" that allows one to simply determine how long to run a chlorate cell. I created another (similar) form, Current Efficiency Worksheet for KClO3 electrolysis based upon wet and dry mass, and bundled the two. This form calculates the current efficiency of your cell, based upon both the dry yield, and the probably mass of the still aqueous KClO3.

Done purely for fun... hopefully someone will find it useful. It's on page two of this PDF file. Download here.

Current Efficiency Worksheet for KClO3 electrolysis based upon

wet and dry mass

Note: with certain lines, an example (in parentheses) is provided.

1) Mass of your dry KClO3 in grams (3,550) M = ________

2) Volume of your cell (V) in liters (25) V = ________

3) Temperature of electrolyte AFTER cooling, and

separation of your main solid yield (20) T = ________

4) Enter the chart below at T on the X axis. Enter

the value of grams per 100ml water KClO3 (7) ________

5) Multiply line 4 by 10 (70) ________

6) Multiply line 2 and line 5 (1,750) Wet Yield = ________

7) Add line 1 to line 6 (5,300) Total Yield = ________

8) Ampere-Hours for the run? (8,725) AH = ________

9) Multiply line 7 by 131.22 (695,466) ________

10) Result: Divide line 9 by line 8 (79.7) CE = ________

 

Hey! I like it!!! Thanks for sharing this, Swede. You're way more creative in your spare time than I am (keep up the good work!).

 

WSM

[pyrojig]

I second that !! Thank you for the useful chart. I do like things like this. I made a running sheet on on excel , and it was a great tool , it calculated everything, From CE to amounts of starting material to load into the cell. Run-times and other useful stuff. Acid additions was a nice part, but my sheet lacked the "reduced stage" when the cell hit what I called the "sweet spot". It is a stage where little to no acid is added due to the stabilized liquor. All these chart are wonderful for logging info, and tracking success . It is a great tool to see where your CE is at , and to tell if your getting the most out of the sys. I believe that I was hitting high 70's% CE with my B.C. sys. using acid control (sadly by hand, which was not optimal, 3x a day) , but better than a uncontrolled sys.

Strangely I noted that the more spot on I was with the ph, the crystals grew large and huge platelets formed. overly acid , formed more cubical crystals, and lack of ph control seemed to be smaller platelets. Im sure that temp had something to do as well, in the formation of these beauties. More to research I guess.

This is where a IV or timed Acid control , will be most beneficial.

Keep up the great work Swede!!!! WE LOVE IT!! It is great to see the wonderful work and art you create !

[Swede]

Thanks guys - I just wish I had 200 acres in a rural area to actually do pyrotechnics, but until that becomes a reality (if ever) - this is fun to do.

 

I revisited the tube anode concept. I thought he idea of packing fine stranded copper in there would be the best option, I took the first tube abode I ever made (it was hollow) and pulled the end cap and also the delrin plug, leaving only the tube. I stripped a piece of #2 Cu welding cable, and cut the copper to a length such that, when packed into the shank, there'd be about 20mm of void space at the top.

 

http://www.5bears.com/perc/cu01.jpg

 

Next, the Cu strands (and the interior of the Ti) was painted with a solution of rosin flux and alcohol. Note that no soft solder made is going to stick to titanium, but I wanted plenty of flux in there for capillary action.

 

http://www.5bears.com/perc/cu02.jpg

 

The coated Cu was packed in HARD with a plastic ramming rod.

 

http://www.5bears.com/perc/cu04.jpg

 

I began to apply heat, then let the plumbing solder flow right in. I could tell the solder was being drawn deep into the shank. I wanted to avoid having just a bubble of tin or solder at the top of the tube. Of course, the rosin flux ignited and made a nice little road flare for a while. Carbon and other goo inside is not a problem so long as there is good contact between the interior Cu and the Ti tube wall.

 

http://www.5bears.com/perc/cu05.jpg

[Swede]

It took a LOT of solder. I switched over to pure tin. A while back, I had purchased a roll of pure tin wire which is about 6mm diameter, nice and thick. I used this to top off the void of the tubing. With a section of pure molten tin at the top, I simply hand held a piece of 316 stainless 1/4" x 20 threaded rod to act as a stud.

 

http://www.5bears.com/perc/cu06.jpg

 

http://www.5bears.com/perc/cu07.jpg

 

By screwing a nut down while it (the solder) was still soft, it aligned the stud perfectly. And the nut itself was not soldered to the system, and could be removed if needed. The final result is a permanently affixed stud, a nut, 2 washers, and a second nut, with the Cu power lug to be positioned between the washers.

 

 

A little clean up with soap, water, and a scotch-brite abrasive pad removed all the rosin flux and gunk from the exterior of the Ti tube, making it nice and shiny. the end result is a tube that will easily carry 100+ amps without warming appreciably. While really labor intensive, this method is (I think) the way to go for tube anode shanks. Cu is much cheaper than solder, and conducts better to boot.

Edited October 23, 2012 by Swede