The Bucket Cell - Start to Finish

[Bobosan]

May have been Wouter Vissers work;

 

"2.4 Cell volume

This is the main factor affecting a cells capacity, provided the power supply can provide the necessary current. As a rule of thumb no more than 2 amperes per 100 ml of electrolyte must be passed through a chlorate cell. Under more optimal conditions a higher amperage may be tolarable, still maintaining reasonable efficiency whereas in less optimal conditions 2 amperes may be too high and a lot of chlorine will be lost, leading to lower efficiency and rising pH. A current of 2 amperes will convert approximately 0.73 gram of sodium chloride to 1.32g of sodium chlorate per hour (assuming 100% efficiency). "

[WSM]

May have been Wouter Vissers work;

 

"2.4 Cell volume

This is the main factor affecting a cells capacity, provided the power supply can provide the necessary current. As a rule of thumb no more than 2 amperes per 100 ml of electrolyte must be passed through a chlorate cell. Under more optimal conditions a higher amperage may be tolarable, still maintaining reasonable efficiency whereas in less optimal conditions 2 amperes may be too high and a lot of chlorine will be lost, leading to lower efficiency and rising pH. A current of 2 amperes will convert approximately 0.73 gram of sodium chloride to 1.32g of sodium chlorate per hour (assuming 100% efficiency). "

 

From those numbers I just calculated my one gallon pickel jar cell (about 3L capacity) would take 60A! Wow, that seems like a lot. I actually ran it at 24A at most and still completed the first run in about 36 hours. I used a regulated power supply (5Vdc 30A) while monitoring voltage, current and temperature. I pulled the plug when the chloride supply dropped the current draw to 11A.

 

 

It was an initial run w/o pH control so the chlorate yield was minimal, but the precursors and chlorate in solution were excellent. Had I recharged the electrolyte with chloride and run it again, I expect it would have produced an excellent yield of chlorate crystals (but nothing close to Wouter's theoretical yield quoted above).

 

My own best guess for peak yield is 19g KClO₃ for every 12g of KCl I start with. That's roughly 60 Lbs of oxidizer from every 40 Lb bag of salt.

Not bad .

 

WSM

Edited March 9, 2014 by WSM

[Bobosan]

60 pounds out from 40 pounds in sound like nice production numbers for sure!

 

Been watching this thread and seeing practical applications you guys are doing vs. Vissers work.

 

No plans to build a cell right now but it is valuable info for future reference. Back to lurk and learn mode.

[WSM]

60 pounds out from 40 pounds in sound like nice production numbers for sure!

 

Been watching this thread and seeing practical applications you guys are doing vs. Vissers work.

 

No plans to build a cell right now but it is valuable info for future reference. Back to lurk and learn mode.

 

I think those numbers are conservative enough but probably represent a high efficiency system. It dawned on me recently that Visser's work may be with sodium rather than potassium so maybe his numbers aren't as ambitious as I first thought.

 

As a fellow enthusiast, if you need help when you're ready to take the plunge, PM me.

 

WSM

[Bobosan]

Yes, it was sodium he was using to arrive at amperage numbers.

[Arthur]

From the patents and other papers I've read, industrial production IS done using the sodium salt the chlorate is cleaned and taken to a cell with platinum electrodes for the perchlorate process then KCl is added to precipitate the Perc as the K salt, and regenerate the primary cell electrolyte with chloride ions. The two advantages are high product solubility and high current densities, the dis advantage is the risk of Na contamination in the product.

 

I recall reading posts from someone to say that he had made perc by using platinum wire from a jewellers as an electrode. Once we have a chlorate source then perc is only a cell away as long as you really go for platinum electrodes, and enough surface area to let a few amps flow without erosion

[WSM]

From the patents and other papers I've read, industrial production IS done using the sodium salt the chlorate is cleaned and taken to a cell with platinum electrodes for the perchlorate process then KCl is added to precipitate the Perc as the K salt, and regenerate the primary cell electrolyte with chloride ions. The two advantages are high product solubility and high current densities, the dis advantage is the risk of Na contamination in the product.

 

I recall reading posts from someone to say that he had made perc by using platinum wire from a jewellers as an electrode. Once we have a chlorate source then perc is only a cell away as long as you really go for platinum electrodes, and enough surface area to let a few amps flow without erosion

That's what I've read too. The solubilities work FOR you rather than against you in that case. Either platinum OR beta form (hard crystalline) lead dioxide work to convert the chlorate to perchlorate, in the next step.

 

Jewellers platinum is typically alloyed with iridium which doesn't appear to cause any problem for perchlorate production.

 

Removing any sodium contamination from the potassium perchlorate formed should be easy if the freshly formed salt is immediately filtered in a vacuum filtration setup and washed with chilled deionized water. Here again the solubilies work FOR us and not against us.

 

WSM

Edited March 11, 2014 by WSM

[pyrojig]

Well here comes the fun part......Harvest !! The starting salt was somewhere around 11# and the Kclo3 resulting appears to be around the 13# by the looks of the amount in the filter .

This is a pic of the freshly harvested material being washed with ice cold distilled water. It almost filled up the Duda Diesel filter ( which is a good sign of a healthy harvest) . The filtrate is left to drip for a hour, then transferred to a tray to be fan dried.

http://i918.photobucket.com/albums/ad24/pyrojig/photobucket-2577-1395117404034.jpg

[pyrojig]

Here is the recharging process right after harvesting the crystals from the mother liqueur. . 6100g of fresh salt is redissolved while the liqueur temp is fairly warm still./ What is left over undissolved will be filtered out and kept for other runs. The dissolved amount is logged in to track CE .. http://i918.photobucket.com/albums/ad24/pyrojig/photobucket-4868-1395118173598.jpg

[WSM]

Here is the recharging process right after harvesting the crystals from the mother liqueur. . 6100g of fresh salt is redissolved while the liqueur temp is fairly warm still./ What is left over undissolved will be filtered out and kept for other runs. The dissolved amount is logged in to track CE ..

 

Hi pyrojig,

 

Looks good. Are you doing the second run with or without pH control? I imagine with pH control, your second run should yield about 8.7 Kg !!! That's figuring a 90% yield due to a setup running at a pH of 6.8,or close to it.

 

WSM

[WSM]

Well, this has been a very long test phase for 1 run. The target AMP drop is about 19-20A when the plug will be pulled, the electrolyte processed ,filtered, and recharged again . I am sitting around the 23-24A range now. I am now at the 30day mark from startup . The cell was run W/O ph control as a comparison to running ph controlled. I hope to cut the run times down to 1/2 that ( maybe 15days at most) .

 

I threw out a interesting idea to WSM to chew on . Any others following this are welcome to chime in as well with ideas. It seems that the system I ran with larger electrodes spaced further apart ( 3") produced more chlorate ( better CE ) than the use of smaller electrodes with tight tolerances (1/8"). The Amp draw was adjusted by the spacing of the electrodes in the cell by distance. The smaller fixed electrodes do not have that option ( they are build specific for a certain Amp draw.) Is there any gain by using the larger electrodes spaced further apart to get " more surface area working for you in the cell?

 

An interesting thought about larger electrodes. I still think they should be positioned lower in the cell to promote good circulation due to "hydrogen lift", which would mean longer leads (and I think larger diameter, filled leads shouldn't get so hot).

 

Did you run your old setup with one cathode? I wonder how it would work with two cathodes (surrounding the anode)?

 

Lots of room for experimentation and discovery. It's probably best to change only one variable at a time, to see the results clearly. Let us know what you think.

 

WSM

[pyrojig]

@Wsm: Yes the anode was surrounded by two cathodes . What is strange is the longer ones do help the cell maintain lift and even heat distribution. But strangely I had good production with the fat and stubby electrodes of same surface area.( almost seemed like more at times).

*The next run will be a PH controlled one. The 1st was done for a CE comparison .

 

The starting salt was about 11# and the yield was right at 12# of Kclo3. I harvested when the cell was fairly warm probably around 100*F So there was a fair amount still in the liqueur. The Final CE #s will have to be calculated soon . I could see some of the kclo3 precipitate out as the liqueur was recharged with KCL.

[WSM]

@Wsm: Yes the anode was surrounded by two cathodes . What is strange is the longer ones do help the cell maintain lift and even heat distribution. But strangely I had good production with the fat and stubby electrodes of same surface area.( almost seemed like more at times).

*The next run will be a PH controlled one. The 1st was done for a CE comparison .

 

The starting salt was about 11# and the yield was right at 12# of Kclo3. I harvested when the cell was fairly warm probably around 100*F So there was a fair amount still in the liqueur. The Final CE #s will have to be calculated soon . I could see some of the kclo3 precipitate out as the liqueur was recharged with KCL.

 

There are two contributing factors I can think of:

1) as the electrolyte is cooling, more chlorate is dropping out of solution, but even more important

2) the electrolyte can only hold so much dissolved salt, and when more KCl is added the KClO₃ is displaced and drops out of solution

 

Likely a combination of factors is at play here by my thinking. Thanks for the updates.

 

WSM

Edited March 25, 2014 by WSM

[WSM]

I appologize for the repeat post. The next post is the intended one...

 

WSM

Edited August 1, 2014 by WSM

[WSM]

Copied from the (per)chlorate thread:

 

It's fun discussing Soxhlet extractors, but I'm thinking more about the chlorate process. I'm getting ready to remake a set of electrodes for our friend, pyrojig. Since his bucket cell ran so hot, and he had issues with the long narrow electrodes; my thinking is to make the electrodes more square (rectangle, actually), with larger diameter tubular titanium leads placed further apart, and possibly with a slightly greater gap between the anode and cathode pair.

 

I'm planning on using 3/8" diameter (~9.5mm) titanium leads spaced about 2.125" (54mm) apart; which will match a pair of tapped ports in his BCA (bucket cell adapter). I'll probably post photos in the Bucket Cell thread when I manage to do all this...

 

WSM

 

 

I'm wondering whether 3/8" diameter tubular titanium leads are large enough or whether I'll have to step them up to 1/2" leads. I'll make the 3/8" first and let pyrojig try them out.

 

Depending on his experiences, we'll determine whether it's worthwhile to increase the lead diameter or not.

 

WSM

Edited August 1, 2014 by WSM

[pyrojig]

Awesome !!! sorry for such a late response, been really busy moving . I would be thrilled to get some larger " re-engineered " Electrodes . Boy that is a very generous offer . I hope to collect some great data for you to make it worth the efforts your putting forth .

Thank you BTW!!

[WSM]

I'm wondering whether 3/8" diameter tubular titanium leads are large enough or whether I'll have to step them up to 1/2" leads. I'll make the 3/8" first and let pyrojig try them out.

Depending on his experiences, we'll determine whether it's worthwhile to increase the lead diameter or not.

WSM

 

I've gotten started on these electrodes yesterday and just need to cut two CP titanium plates to use as cathodes to surround the anode. I've prepared the tubular leads, so I just need to put it all together and deliver it all to pyrojig to try them out. The configuration is changing to more rectangular electrodes and greater spacing between them to hopefully reduce the heating problems encountered with the first set.

 

After I spot weld the electrodes to the titanium tubing (with the top end threaded), I wrap the electrode with a paper towel or shop rag, gently clamp it in a soft jaw vice and heat the tube with a torch and melt in lead-free solder (95% tin) and fill the tube. The tin filler is about five times more conductive than titanium, which helps cut down on heating problems. Next I drill out the solder in the thread area and chase the threads with the tap. All that's required is to put in the screw and washers (usually stainless steel, but brass should work just fine), and the electrode is ready to go.

 

With the round leads, the electrodes can be held tightly and without leaks in a compression fitting. The material of choice is the fluoropolymer, PVDF (or Kynar), which is modified slightly by drilling through the fitting so the electrode lead can go through it, where it is held tightly and without leaks.

 

WSM

Edited October 20, 2014 by WSM

[pyrojig]

Awesome to see some advancements on the electrodes !!! I noticed that the electrodes I ran a couple years ago that where more of a square shape seemed to perform quite well. I always assumed that the use of longer electrodes promoted the "hydrogen lift" . This of course is good for circulation , but I wonder if it is really necessary, or if electrode placement is more critical to the even distribution of heat/circulation .

[WSM]

Awesome to see some advancements on the electrodes !!! I noticed that the electrodes I ran a couple years ago that where more of a square shape seemed to perform quite well. I always assumed that the use of longer electrodes promoted the "hydrogen lift" . This of course is good for circulation , but I wonder if it is really necessary, or if electrode placement is more critical to the even distribution of heat/circulation .

 

I've always felt that placement of the electrodes lower in the cell would promote circulation (and uniform heating) the best, plus pH control encourages the "bulk reaction" where chlorate is being produced throughout the cell and not just at the electrodes (the "brute force" method, to quote Swede). We'll see if the new electrodes will work better, plus whether the 3/8" diameter leads are big enough or if we need to go to 1/2" diameter.

 

I sent Swede samples of my 1/4" and 5/16" diameter CP titanium tubing and he ran tests on them. I was dissapointed on how quickly they heated up when the current got a little bit high. That's why I sought out and bought larger sizes of tubing. I don't remember if he filled the tubes or ran them empty. That would make a huge difference.

 

WSM

Edited October 22, 2014 by WSM

[pyrojig]

I guess another option would be strapping a heat sink to the leads on the top-side . This may help a little as well, if heat where a persisting issue. But as you say, the filled electrode leads should dissipate the heat and not be so bad.

[WSM]

I guess another option would be strapping a heat sink to the leads on the top-side . This may help a little as well, if heat where a persisting issue. But as you say, the filled electrode leads should dissipate the heat and not be so bad.

 

Yeah, I think so too. The problem with using heatsinks is they're so bulky, they might short out electrically if the leads are too close to each other. I'm sure the problem can be circumvented with proper placement of the right configuration of heatsink. If they're too small, fans can help but I prefer keeping things as simple as possible (making the tubular leads large enough and filling them with high conductivity filler should prevent them from heating too much in the first place).

 

We'll see...

 

WSM

[WSM]

From the patents and other papers I've read, industrial production IS done using the sodium salt the chlorate is cleaned and taken to a cell with platinum electrodes for the perchlorate process then KCl is added to precipitate the Perc as the K salt, and regenerate the primary cell electrolyte with chloride ions. The two advantages are high product solubility and high current densities, the dis advantage is the risk of Na contamination in the product.

I recall reading posts from someone to say that he had made perc by using platinum wire from a jewellers as an electrode. Once we have a chlorate source then perc is only a cell away as long as you really go for platinum electrodes, and enough surface area to let a few amps flow without erosion

 

I wonder if our concerns about sodium contamination in the final product are overblown? I did a calculation based on the relative solubilities of sodium perchlorate and potassium perchlorate; I believe the potassium salt is about one percent (1%) the solubility of the sodium salt.

 

At that rate, a simple wash with cold distilled water after vacuum filtering the KClO₄, should leave the final product pure enough to use, as is, when dried and powdered. When used, I expect there'll be no sodium contamination to speak of.

 

WSM

[WSM]

I'm back from a lengthy Holiday road trip, visiting family and friends, and have started to settle into a new job assignment. All this has put any research on the back burner, but I hope I can get back into some metal working and prepare the electrodes to meet my goals (evenings and weekends, at least).

 

I hoped to make some progress yesterday, but the weather (rain) was not helping. Maybe next week...

 

I'm glad to be back.

 

WSM

Edited January 11, 2015 by WSM

[WSM]

...I hope I can get back into some metal working and prepare the electrodes to meet my goals (evenings and weekends, at least).

I hoped to make some progress yesterday, but the weather (rain) was not helping. Maybe next week...

WSM

 

Yesterday, I was able to cut several pieces of 0.050" (1.27mm) thick CP titanium sheet for use as cathode plates. I like to surround the anode with cathodes to maximize the efficiency of the cell. Also the electrical stresses on the anode are more evenly distributed with cathodes on both sides, in a running cell.

 

Now I need to fabricate replacement electrodes with larger diameter, filled tubular leads for pyrojig's bucket cell, so we can see if the system runs better.

 

WSM

Edited January 20, 2015 by WSM

[WSM]

Yesterday, I was able to cut several pieces of 0.050" (1.27mm) thick CP titanium sheet for use as cathode plates. I like to surround the anode with cathodes to maximize the efficiency of the cell. Also the electrical stresses on the anode are more evenly distributed with cathodes on both sides, in a running cell.

Now I need to fabricate replacement electrodes with larger diameter, filled tubular leads for pyrojig's bucket cell, so we can see if the system runs better.

WSM

 

Those cut materials have been waiting dutifully in a box for me to get around to assembling them for pyrojig to use in his bucket cell. My "free" time has been occupied with research and writing the Homegrown Oxidizers articles for the PGI Bulletin, and between work concerns and family matters. I confess, pyrojig's electrodes have been on the back burner for far too long.

 

On the bright side, while preparing and running electrodes for the sodium perchlorate cells, I've proven for myself that the design is sound and pyrojig shouldn't have near the heating troubles he's seen so far. I think the replacement electrodes should work great in his bucket cell.

 

Here is a photo of an LD electrode setup in an experimental sodium perchlorate cell, using the same type of filled titanium leads I'm preparing for pyrojig's bucket cell:

 

If you look carefully at this photo, you'll see smooth, dark edges where the cathode connecting straps on the sides touch the edge of the anode. Due to the close proximity of those straps, I took pieces of thin walled Viton tubing, cut them lengthwise with medical bandage scissors, and fit them on the edges of the LD anode. This was done for two reasons: 1) to physically protect the fragile LD coating from chipping or abrading, and 2) to electrically insulate the electrodes from each other while maintaining their close fit. The Viton tubing is very strong and holds firmly to the edges of the anode, plus withstands the rigors of the electrochemical cell's environment.

 

I also need to modify larger PVDF (Kynar) compression fittings to hold the electrode leads tightly, and without leaking, in the BCA.

 

I expect we'll here good reports about their performance when all this is done, delivered and put into service; later this year.

 

WSM

 

Edit: pyrojig has already inquired about adapting the LD (perchlorate) anode for use in the bucket cell. From what I've seen so far, I see no reason why it wouldn't work quite well. In fact, a third bucket cell set up to make sodium chlorate feed stock for the perchlorate cell would probably be a good idea!

Edited June 28, 2015 by WSM