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Author: Subject: The trials & tribulations of Thorium production
Dan Vizine
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[*] posted on 24-9-2015 at 07:51


The hydrolysis step appears to be easier than anticipated. The reactor was fitted with a plastic funnel, cooled in an ice-bath and 3 x 80 mL H2O was added in a thin stream. Each time, the reaction was allowed to proceed until the slurry seen in the funnel stem became too thick to allow gas out easily. This slurry was collected in a 1 L beaker. The next portion of H2O was added, etc. A smell was noticed. It could be from a gas or a microscopic mist. I think this should be enclosed when being done and a long period allowed for all possible mist to settle out.

Shown are a few seconds of hydrolysis 1 and pictures of #1, #2 and #3 which show decreasing reaction rates.

Attachment: 2015-09-24 10.28.23.mp4 (7.7MB)
This file has been downloaded 383 times hydrolysis (1).jpg - 225kB hydrolysis (2).jpg - 182kB hydrolysis (3).jpg - 221kB

[Edited on 24-9-2015 by Dan Vizine]





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[*] posted on 2-10-2015 at 07:07


A couple things learned in the trial run w/o ThO2:

a) The Ca(OH)2 formed is a real nuisance. Now I understand what was implicit in the patents, that it is not dissolved away (solubility = 1.7 g/L @ 20 C), but rather poured of with the supernatant liquid. This explains why the thorium is obtained in two forms, heavy grains which settle much faster than Ca(OH)2 and in the form of "fines" which are decanted off with much of the un-dissolved Ca(OH)2. This is a further handling/isolation issue to address once the majority of the Th is recovered.

b) The presence of oxidation on the 1/4" NPT threads of the pipe which screwed into the reactor indicates some oxygen diffusion. This led to two decisions. The first will be the inclusion of a minimum practical amount of a 2600 F nickel platelet/graphite anti-seize lubricant on the outer 1/2 of the threads. The second has to do with the 1/4" NPT to 1/2" NPT bushing used for the intended reactor. The bushing is rust-resistant steel, not stainless. I want it gone. So, I cut the 1/4" male NPT threaded end off of where I welded it to the pipe, and used a 1/4" NPT pipe die to cut threads in it. I had a solid 1/2" NPT 316 SS pipe plug, with very high quality threads. I bored a concentric hole through the middle and will thread this with a 1/4" NPT tap. After very tightly screwing this together, it will be welded all the way around with Weldmold 880 (a superb welding rod, about 8 to 10 times the cost of SS rods, but what an incredible performer!). This weld won't come in contact with the reaction mixture, so the high alloy content won't worry me.

I have very nearly addressed every single mechanical aspect of doing the reduction cleanly.

One thing I wonder about, though. Since both the Ca and the Ca(Cl)2 will be molten, and the reactor will be turning at an angle and contains 3 large Macadamia nut sized 309 SS lumps for stirring, why are Ca shavings and powdered Ca(Cl)2 needed? It would be preferable, from the standpoint of moisture exclusion, to add cleaned Ca lumps and fused pieces of Ca(Cl)2 directly to the reactor. The mild "ball-milling" which will take place ought to homogenize the reaction mixture. Any thoughts on why this may not be desirable?





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[*] posted on 2-10-2015 at 16:40


I can't think of any reason why you need to use powder/granules if the result is liquid.

I am vicariously loving this saga. Thanks for keeping us informed even though not many of us are able to contribute much.
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[*] posted on 6-10-2015 at 18:40


Well, a few mundane but useful facts were learned:

a) Complete work-up of the blank, run in SS 304, gave only a few milligrams of insoluble gray material (perhaps too small to even collect and weigh). This bodes well for minimal metallic impurities in the product.

b) Without a thread sealant, no amount of torque can seal the threads entirely gas-tight. My one concern is the hydrocarbon and graphite that will burn off the sealant and cause minimal C contamination of the Th. If that's the case, it still greatly beats O2 contamination.

c) I used 1.5 times the specified amount of dilute HNO3 to dissolve all of the Ca (OH)2. If some Th is lost, it will be (recovered) worth it to avoid solid-bearing mists from high speed agitation.

Re-made.jpg - 468kB





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[*] posted on 7-10-2015 at 05:38


Quote: Originally posted by Dan Vizine  

b) Without a thread sealant, no amount of torque can seal the threads entirely gas-tight

Not surprising. Even though NPT are considered fluid-tight it requires exceptional tolerances or that one part can yield. If a sealant isn't desirable a gasket or crush washer between the two nuts should work.




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[*] posted on 7-10-2015 at 10:09


I've thought about those options, but I didn't have any bright ideas on what to use.

That area will be in air for a minimum of 1 hour, and ideally several hours, at something approaching 1000 C. That rules out so many options that it's ridiculous.

And given that it needs to be soft enough to deform sufficiently to become gas-tight....tough nut to crack.

I think very, very thin platinum foil could work as a Teflon tape substitute, something along the lines of cheap brands of aluminum foil.

The other sealant I considered was MoS2. It has a very high mp but the literature says:
Ambient Temperature Range -185 to 350 ºC
Vacuum Temperature Range -185 to 1100°C at 10-14 Torr
So, it may not be the best option.

The graphite/nickel platelet formulation claims a 2600 F rating. I plan a few experiments where I put the mix on male threads, bake it at different temperatures, and compare the sealing properties of the baked mixture with the normally applied paste.





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[*] posted on 7-10-2015 at 19:37


That is some serious conditions, bro. But does it have to be completely oxidation proof? Only the outer surface will oxidize, so as long as it's diameter is large some loss shouldn't affect the seal. And any oxygen leaking through the mating surfaces would oxidize the material, wouldn't this produce an increase in volume that could cause it to be self sealing. Not sure if that would work, but it's worth some consideration.

One other problem with a gasket like this is the thermal expansion, if it is different from the vessel it could cause problems either during heating or subsequent cooling. So a thin gasket would probably be the safest option.




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[*] posted on 27-7-2016 at 19:35


Tomorrow.

2016-07-27 20.41.35.jpg - 2.2MB





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[*] posted on 27-7-2016 at 19:37


YAYYY!!! Such a fun project to follow :) thanks for sharing



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[*] posted on 27-7-2016 at 19:42
Thorium production moved to Radiochem.


This move was surprising, in that radiochemistry is merely one of the characteristics of the desired product. This is a synthesis topic. Always has been.

And it will happen tomorrow.
http://www.sciencemadness.org/talk/viewthread.php?tid=29927&...

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[*] posted on 27-7-2016 at 19:48


Agreed. Surprising. Following this I think that the major challenges have been engineering ones to cope with the extreme nature of the chemistry involved. It makes as much sense to put it in technochemistry as it does in radiochemistry.


(Shouldn't this thread be in Forum Matters? :P)




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[*] posted on 27-7-2016 at 20:01


Sorry, I moved it without thinking much of it. I'll put it back in Chemistry in general and merge this to it. No problem.



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Dan Vizine
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[*] posted on 28-7-2016 at 10:25


Thank you, zts 16.

And now, on with the show.

I'll prepare a detailed write-up to accompany this prep.

For now, here are some visuals:
https://www.dropbox.com/s/w7p1lr0m47dduky/Start%20of%20Th%20...

This is a short clip of the start of the reduction (initial heating).

I'm now at 950 C (2:20 PM).

2016-07-28 13.37.38.jpg - 3MB





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[*] posted on 28-7-2016 at 14:19


Dan:

Tell me again what is the purpose of the inclination?




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Dan Vizine
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[*] posted on 29-7-2016 at 10:49


Quote: Originally posted by blogfast25  
Dan:

Tell me again what is the purpose of the inclination?


It's to achieve good mixing. If it were vertical, stirring wouldn't be as good. The original workers milled their charges to get a homogeneous mixture. That wasn't easy, practical or safe for me.





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[*] posted on 29-7-2016 at 11:12


Quote: Originally posted by Fulmen  
That is some serious conditions, bro. But does it have to be completely oxidation proof? Only the outer surface will oxidize, so as long as it's diameter is large some loss shouldn't affect the seal. And any oxygen leaking through the mating surfaces would oxidize the material, wouldn't this produce an increase in volume that could cause it to be self sealing. Not sure if that would work, but it's worth some consideration.

One other problem with a gasket like this is the thermal expansion, if it is different from the vessel it could cause problems either during heating or subsequent cooling. So a thin gasket would probably be the safest option.


A practical metal gasket for threaded connectors? I didn't know they existed. Funny you should mention oxidation though..."heat-resistant" SS 308 seemed to fare far worse at 950 C than the SS 304 that I usually use. That forms a tightly adherent scale, this eroded away layer by layer. I was certain that I had a reactor breach upon first sight. I'm still inspecting and cleaning the reactor and struggling greatly to unscrew the connecting pipe.

1.jpg - 131kB 3 (2).jpg - 175kB 3 (1).jpg - 116kB

[Edited on 29-7-2016 by Dan Vizine]





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[*] posted on 29-7-2016 at 16:43


@Dan:

Thought as much. Thanks and good luck!




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[*] posted on 29-7-2016 at 17:22


I cleaned thing things up in preparation for hydrolysis in place. Mostly okay, but one area is slightly suspicious. Still assessing. Yes, I know this is glacial. Sorry, but it is progressing....

4.jpg - 2.2MB5.jpg - 2MB6.jpg - 1.8MB





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[*] posted on 30-7-2016 at 11:46


The 1/2" threaded connection yielded to a pipe vise and a 24" pipe wrench.

The reactor was prepared for the "in-place" hydrolysis by thoroughly isolating the reactor's exterior to prevent sloughing off of impurities during submersion. Theoretically the interior should be quite clean.

2016-07-30 15.27.19.jpg - 1.2MB





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[*] posted on 30-7-2016 at 15:18


The interior, what I could see of it, was clean. Hydrolysis was performed as per 9-24-15 trial run, but under a sophisticated cover - a clear acrylic wastepaper basket with a 1/8" hole in the top, er, bottom...you know what I mean, for drop-wise distilled water addition. I'm eating spaghetti, it's ever so slightly effervescing. Tomorrow morning I'll pour it out....




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[*] posted on 31-7-2016 at 11:32


Well, it's done...or getting there. But there's the thorium.....

2016-07-31 15.19.30.jpg - 628kB





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[*] posted on 1-8-2016 at 02:49


Extraordinary thread, just finished reading it all. Bit like a decent book in places, a few twists and turns 'would he bottle it or would he not'.

No idea how dangerous that stuff is but i got the impression its not something to be messed with, so seeing a jar held aloft by hand at the end............I thought 'now thats what you call a utterly MAD scientist!!

I am fully expecting you to be supplying your neighbours next year with self generated nuclear power.

Well done its beyond impressive which ever way you look at it. Why does everything great always look like sludge? Only stuff like sodium chloride seems to look pristine white and fluffy.
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[*] posted on 1-8-2016 at 11:22


I had the same thought, it's a bit anticlimactic to look at.

Thorium is like most primarily alpha emitters. Essentially harmless in the sense that alpha particles don't penetrate skin. But ingested or inhaled alpha emitters are super dangerous, see polonium, plutonium.

Now, on to the final isolation...


[Edited on 2-8-2016 by Dan Vizine]





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[*] posted on 1-8-2016 at 12:08


Quote: Originally posted by Dan Vizine  
I had the same thought, it's a bit anticlimactic to look at.

Thorium is like most primarily alpha emitters. Essentially harmless in the sense that alpha particles don't penetrate skin. But ingested or inhaled alpha emitters with long half-lives are super dangerous, see plutonium.

Now, on to the final isolation...



[Edited on 1-8-2016 by Dan Vizine]


Must be deeply satisfying though after all the effort to finally get your crude product.

Well done its a really inspiring read.
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[*] posted on 1-8-2016 at 12:36



Thank you most sincerely.

The story isn't over by a fair stretch. A good write up needs to be done, all info. in one succinct spot. Anomalies (there was one, as hinted at by the reactor's bottom edge) need analysis. Spoiler..it seems to have been rather benign. And the final product isn't a final product until fully processed, washed, dried, passivated & bottled.

Yes, satisfying and a relief. So many man-hours, so much labor and more than a few $$ were involved. I even built the furnace for this project. The tank of UHP argon was $140, the tig welding was $140, the chemicals were over $800, misc. materials were another $50. Way, way over 100 man-hours all things considered. Perhaps 200.



[Edited on 1-8-2016 by Dan Vizine]





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