making potassium (per) chlorate

[taiwanluthiers]

Where can I get Grade 1 or 2 Titanium? The one I have was Grade 5, and I thought it would only be slightly worse, I had no idea it would dissolve in hours. I cannot find any Ti bolts or nuts that isn't grade 5... and I do not have a lathe so I can't make it.

 

Can someone help me with this?

 

BTW I tested the bolt with a grinder, it sparks just like Ti but the washer on it that was so tightly fit that it will not come off isn't Ti, because it's slightly magnetic.

[Swede]

There's no way Ti should have dissolved like that. I have used both CP and alloys for shanks at 60+ amps and barely had it discolor. Something was definitely off with your hardware.

 

IMO, ANY real titanium hardware on the anode should do fine. I don't know what to tell you other than that indeed your hardware was mislabeled.

[taiwanluthiers]

There's no way Ti should have dissolved like that. I have used both CP and alloys for shanks at 60+ amps and barely had it discolor. Something was definitely off with your hardware.

 

IMO, ANY real titanium hardware on the anode should do fine. I don't know what to tell you other than that indeed your hardware was mislabeled.

 

Well I noticed a steel washer on the hardware... I cannot remove it, it's very tightly fitted to the hardware (and I honestly have NO idea how they got it on in the first place). My theory is that the steel hardware dissolved, leading to an open circuit between the MMO and the Ti strap, and now the screw ended up becoming a Ti anode which as you know doesn't last. This of course continued until the circuit became open. The question is why was it the Titanium strap unharmed? There are visible rust-colored/yellow stains where the screw used to be.

 

I took the bolt to a grinder and it sparks just like Titanium.

 

Now I actually ended up just screwing a regular steel screw into it to attach the MMO, then sealed them with hot melt glue and kept it above the waterline. So far no corrosion.

[pdfbq]

Ti as anode simply does not do anything, look at the bare ti spots on your anode. They are still fine is my wild guess.

Just clamp the anode with a small Ti plate to your Ti shaft with two small ti strips made yourself.

 

[taiwanluthiers]

I thought of that, except I have trouble bending titanium strips enough to actually secure the thing well... I found the hot glue seal actually works fairly well... minimal rusting in the steel bolt.

 

Can anyone tell me is cell temperature important? When I ran it the cell got really hot to the touch (through the bucket wall) so I placed it in a larger bucket of water to cool it down. Is there such a thing as too cool of a cell (as in I would end up making hypochlorite and no chlorate)?

Edited November 29, 2012 by taiwanluthiers

[WSM]

I thought of that, except I have trouble bending titanium strips enough to actually secure the thing well... I found the hot glue seal actually works fairly well... minimal rusting in the steel bolt.

Can anyone tell me is cell temperature important? When I ran it the cell got really hot to the touch (through the bucket wall) so I placed it in a larger bucket of water to cool it down. Is there such a thing as too cool of a cell (as in I would end up making hypochlorite and no chlorate)?

 

I think a cooler cell is a slower cell. There will always be internal resistance within the cell. Electrically, this is seen as inefficiency, and manifests itself as heat. Chemically, the heat speeds or accelerates the reactions. So, the heat is a two-edged sword; it uses more electric power but aids the chemical process.

 

As for creating a cell that produces only hypochlorite and not the other species, I don't know but it would be interesting to find out. That knowledge would be useful in further understanding the process. If you run experiments on this, please post your observations.

 

WSM

[taiwanluthiers]

Well, I don't want to get it too hot, because I am not sure if the container (HDPE bucket with PP lid) will withstand the heat, so I keep it below "hot to the touch" (which generally means around 40C). Plus I read that you can damage MMO by making the cell too hot. Mind you that's the temperature felt from the cell, not what the liquid actually is, which may be a bit higher. The water used to cool the cell actually got quite warm.

 

Is there a calculator out there to let me know how long to run the cell? Is there any visible change in its electrical characteristic when the chloride level got very low, like lower current draw?

[frank]

You can simply use a homemade rivet as pdfbeq suggestes.

If you want a Grade one nut and bolt you can make one easily enough.

If you look hard enough on ebay you will EVENTUALLY turn up grade one

bolts but they are very rare.

 

You need to purchase a tap and die.

Cut a piece of square cross section Grade one and place into a drill. Run drill

and hold a file against the rotating Ti (or your sander/grinder) in order to make a bar

of Ti of the correct diameter. (you can also purchase a bar of grade one or two or three or four!)

Put threads on it using the die.

Drill a hole in a square piece of the grade one and thread it using the tap. This is the nut.

You can make a second nut for to make the 'head' of your bolt or you can bend the

top of your bolt to make the head if you like.

 

This all sounds very complicated/difficult but Ti is easy to machine (its a bit like brass) and precision

is not required, just a working nut and bolt.

 

Frank

[Swede]

Well, I don't want to get it too hot, because I am not sure if the container (HDPE bucket with PP lid) will withstand the heat, so I keep it below "hot to the touch" (which generally means around 40C). Plus I read that you can damage MMO by making the cell too hot. Mind you that's the temperature felt from the cell, not what the liquid actually is, which may be a bit higher. The water used to cool the cell actually got quite warm.

 

Is there a calculator out there to let me know how long to run the cell? Is there any visible change in its electrical characteristic when the chloride level got very low, like lower current draw?

 

Length of run worksheet

 

Heat is generally beneficial and improves current efficiency, but your cell materials need to be monitored. I think there's probably going to be nothing wrong with 60 C or even higher, but there's nothing wrong with being conservative.

 

If your hot glue is above the liquor level, it'll last longer, but it's still going to suffer some degradation. You have to remember that gaseous chlorine is evolved, and there's not much that can withstand chlorine indefinitely.

 

If you can find genuine titanium bolts and nuts with no other materials, then they should last forever.

 

If you have any questions on that length of run work sheet, ask away.

[taiwanluthiers]

Ok I finally made a few Ti nails and bent them around the strap to hold it in place... its the same material as the strap so it should not dissolve. I used that same Ti bolt and sealed it with hot glue but eventually the liquid got through and began attacking the bolt. Now my electrolyte has a small amount of brown/black contaminants from the bolt dissolving, is it ok to continue and just purify the result when complete?

[WSM]

Ok I finally made a few Ti nails and bent them around the strap to hold it in place... its the same material as the strap so it should not dissolve. I used that same Ti bolt and sealed it with hot glue but eventually the liquid got through and began attacking the bolt. Now my electrolyte has a small amount of brown/black contaminants from the bolt dissolving, is it ok to continue and just purify the result when complete?

 

The choice is yours. I lean toward starting over with fresh electrolyte to see the difference. You may well want to complete the run and see if you can purify it through crystallization.

 

Either way, I'd clean the electrodes with a fifteen to thirty minute HCl bath, followed by a water rinse before starting over with fresh electrolyte. This way you eliminate any contamination from the first run.

 

Do you have the ability to take digital photos and post them? It would be nice to see what you're describing. Photos could help us make better, more useful suggestions as well.

 

WSM

[taiwanluthiers]

Ok, here is what I have...

 

There's a bit of iron and titanium/aluminum contamination from the Grade 5 Ti bolts and the steel bolts that partially dissolved. I have since secured the MMO with homemade Ti nails that are of the same material as the strap (Grade 2 Ti) and they do not dissolve at all.

[WSM]

Ok, here is what I have...

There's a bit of iron and titanium/aluminum contamination from the Grade 5 Ti bolts and the steel bolts that partially dissolved. I have since secured the MMO with homemade Ti nails that are of the same material as the strap (Grade 2 Ti) and they do not dissolve at all.

 

That looks like it'll work. I noticed the condensation in the vent tube; when the cell is operating do you have the vent tube running upward to vent the hydrogen? Also the electrodes look large for the size of the cell, what's the length and width of the anode?

 

WSM

[taiwanluthiers]

So there's not supposed to be condensation on the vent tube? there's a lot of solution spray inside and its gotta go somewhere, the vent tube kinda condenses the evaporated solution (its quite hot) and deposits it back. The tube is vented outside.

 

The electrode is quite large, and can probably handle a lot more than 10 amps, it's about 2.5" x 5". I feel its better to be too big than too little, because there's no sense in having a too high of current density.

[WSM]

So there's not supposed to be condensation on the vent tube? there's a lot of solution spray inside and its gotta go somewhere, the vent tube kinda condenses the evaporated solution (its quite hot) and deposits it back. The tube is vented outside.

The electrode is quite large, and can probably handle a lot more than 10 amps, it's about 2.5" x 5". I feel its better to be too big than too little, because there's no sense in having a too high of current density.

 

Then your vent tube is working okay? Good.

 

That size of anode could handle 24A with a single cathode and 48A when surrounded by two cathodes. So, either a 30A power supply or a 60A supply would be recommended depending on your electrode configuration.

 

You understand that I come from an electrical background and prefer to load a power supply to no more than 80% of its total capacity, for safety's sake. So I taylor the electrodes to the power supply rather than the other way around.

 

Also, I tend to be conservative with the current and calculate based on 0.3 A per cm², even though the MMO can probably handle more.

 

Thanks for sharing the photos, they really help.

 

WSM

Edited December 4, 2012 by WSM

[taiwanluthiers]

Is there anything to look out for when the run is almost complete? I notice the current draw dropping slightly, is that an indication that I should stop?

 

I don't have any way of measuring chloride level...

[WSM]

Is there anything to look out for when the run is almost complete? I notice the current draw dropping slightly, is that an indication that I should stop?

I don't have any way of measuring chloride level...

 

One rule of thumb I've used is to pull the plug when the current drops to 50% of the starting current.

 

Be sure to remove the electrodes from the electrolyte when the power is shut off, to avoid damage to the electrodes.

 

WSM

Edited December 4, 2012 by WSM

[taiwanluthiers]

That sounds reasonable... it started at around 10 amps but went up to 14-15 amps when the cell got hot. Now its back down to 10 amps and I think I'll pull the plug when it reaches 6 amps or so. That should take a day or 2...

[WSM]

That sounds reasonable... it started at around 10 amps but went up to 14-15 amps when the cell got hot. Now its back down to 10 amps and I think I'll pull the plug when it reaches 6 amps or so. That should take a day or 2...

 

Another point Swede has brought up is when your cell is roughly 25% filled with crystals, your chloride will be mostly depleated.

 

I think that applies when you are starting with recharged (with new chloride) liquor on the second run and afterward. The first run won't produce as many crystals as subsequent runs will, because they start out with chloride, hypochlorite, hypochlorous acid and dissolved chlorate ions. After the first run, crystals of chlorate will form almost immediately; forced out of solution because of the saturation of the mother liquor.

 

Have fun.

 

WSM

[WSM]

One rule of thumb I've used is to pull the plug when the current drops to 50% of the starting current.

Be sure to remove the electrodes from the electrolyte when the power is shut off, to avoid damage to the electrodes.

WSM

 

The small experiment I ran almost a year and a half ago (one gallon glass pickle jar) started out at 20A, moved up to 24A when it got warm (55^oC) and I pulled the plug at 11A.

 

I was using two cathodes and one MMO mesh anode (all roughly the same size). The goal was to stop the run when the current draw was half the highest current; in this case 12A. I over-shot a little, but everything was fine. The gains quickly diminish beyond that point, plus it's harder on the anode.

 

When I pulled the plug, I removed the electrodes from the depleated liquor, rinsed and stored them in a dry and protected place; ready for the next run. The whole run was less than two days and the electrodes were about 2" x 3", or 6"² (+- 38cm²), and the electrode spacing was roughly 1/8" (3mm). By surrounding the anode with two cathodes, I maximized the use of the anode. Everything metallic in the cell was CP titanium or MMO on CP titanium (not counting the potassium in solution). I used a 5Vdc, 30A solid state power supply with no added cooling fan. No pH control was used.

 

WSM

[Swede]

The current you saw is very typical. I run a constant current setup, which means for me, the voltage varies, not the current, but the principle remains the same.

 

 

For a fixed voltage system:

When starting with fresh brine, the initial current will be moderate, then rise slowly, peak, then begin to drop, eventually dropping below the starting current.

 

For a constant current setup:

Voltage at start is high, then drops. It bottoms out in the middle portion of the run. As chloride is depleted and chlorate drops out of solution, the voltage rises and then exceeds starting voltage.

 

When I set up a system to do complete data acquisition (voltage, current, temperature), I was hoping to find a consistent mathematical formula that would allow one to determine when a run is nearing completion, but the data I gathered was subtle, and pretty much follows what I described above. It was an interesting experiment, but in the end, not worth the effort.

 

TL, have you considered cutting your MMO so as to use the MMO material itself as an integral shank? You've got a pretty big piece of MMO - you could turn that into TWO anodes by cutting it such that the shanks are offset from the middle. Does this make sense?

[taiwanluthiers]

I understand what you're talking about... I guess I really underestimated the whole anode size thing. If I cut it in half then I would have to do it lengthwise rather than widthwise. I still have another piece the same size. I figure I can always keep the current size and move it to a bigger bucket cell when I get this whole thing down.

 

The issue with an integral shank is that I would need to raise the MMO a bit and I am afraid of the bottom remaining 100% chloride because the solution isn't getting any agitation. I don't really have a way of stirring it constantly.

 

One more thing, should I recharge the solution when finished, or due to its contamination should I just start fresh again? I am using Agricultural KCl which has red stuff in it, how do I go about recharging them? Can I just dissolve the stuff in the liquor and filter it before returning it to the cell?

 

Update: I decided to pull the plug. Once I opened the cell I stuck something into the cell to see if something is in it. I was immediately greeted with at least 3" layer of crystalized stuff. I scooped some of those crystal up and mixed them with lactose to see if they burn, and they burn real well. So I have now dumped the crystals into a bowl to prepare them for recrystalization...

Edited December 5, 2012 by taiwanluthiers

[taiwanluthiers]

Success! I have produced good pyro grade chlorate.

 

I took some of those chlorate and made some Royal Blue from Bill Ofca and tested the loose pile.

 

The thing went up with a blue flame, hard to tell what it's like from the ground, actual stars would have to be made and shot out of a star gun for that. I've recrystalized it a few times to get the rust-colored impurities out and now its pristine. The next batch should be better. I estimate that I have made a few hundred grams of the stuff.

[Swede]

Excellent! As you gain experience, it won't seem like so much effort, and the yields will increase dramatically.

 

Don't skimp on the wash. And of course, you can recharge the old electrolyte over KCl, and it'll give you a HUGE head start on subsequent runs because the liquor is pre-saturated with chlorate and precursors.

[WSM]

Success! I have produced good pyro grade chlorate.

I took some of those chlorate and made some Royal Blue from Bill Ofca and tested the loose pile.

The thing went up with a blue flame, hard to tell what it's like from the ground, actual stars would have to be made and shot out of a star gun for that. I've recrystalized it a few times to get the rust-colored impurities out and now its pristine. The next batch should be better. I estimate that I have made a few hundred grams of the stuff.

 

Wonderful!

 

I suspect if you recrystallize the fertilizer KCl before you put it in the cell, it'll be nice white crystals to start with and make nice clean chlorate right out of the cell (requiring only rinsing and not recrystallizing).

 

Let is know if you try that, and show us photos if you do.

 

WSM

Edited December 7, 2012 by WSM