Gammatron
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Barium carbonate in uranium extraction
In this video by Cody's Lab at 5:23 he adds a small amount of barium carbonate for "increasing barium levels and sequestering sulfate ions". I have read a
lot of literature on U refining and never seen that come up anywhere else, what exactly is accomplished by doing this?
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phlogiston
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As he says @ 10:40, "But that is, of course, why I added the barium into there; it's to help pull the radium out of solution"
The idea is that any Ra that dissolved in the initial leaching of the ore will co-precipitate with BaSO4 when sulphate is added to the filtered
leachate, giving a precipitate of (Ba,Ra)SO4 that can be filtered. Without Ba present, the amount of RaSO4 would be so tiny, it would be impossible to
filter or precipitate efficiently. Most U ores contain a little Ba natively already, so it probably isn't really necessary to add any but it won't
hurt.
Cody's remark about 'sequestering any sulphate ions' is less clear to me. I think his reasoning is that if there would be any sulfate ions in the
initial leaching, any Ra that would otherwise dissolve would immediately precipitate again as RaSO4, and be filtered of and lost to the workup. Adding
Ba to the leaching acid helps to mitigate this, as it competes with Ra for the sulfate ions (and there is a lot more Ba than Ra).
I think he still lost the majority of Ra in the initial filtering step, because Ra in the rock is probably mostly in the form of RaSO4 already, and
that would not have dissolved in the hydrochloric acid leaching solution. He noted that the crushed rock residue that was left after leaching was
still markedly radioactive (@9:56), which he attributed to imperfect crushing. However, I suspect a large part of that residual activity may actually
be undissolved RaSO4.
[Edited on 13-9-2022 by phlogiston]
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"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer |
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Gammatron
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I seem to have missed his comment at 10:40 despite watching this video a few times already. Based on what you've said it does seem a bit unnecessary
as I was hoping it would be since it's kind of expensive. I also have less of a need for complete chemical extraction of U because I have tributyl
phosphate so just getting all the U concentrated will do for me.
Thanks for the help!
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j_sum1
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I would not have thought of Ba salts as being expensive in this context. And other Ba salts would substitute ok for the carbonate.
For the relative simplicity of the process, I would have thought it sensible to remove all Ra. Makes your final product a lot safer to handle.
Granted, the radium is probably already in sulfate form. But a simple step to guarantee this and filter it out seems prudent to me.
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Gammatron
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Just looking on ebay, the cheapest source of BaCO3 is over $45 for 500g, which would be absurd when I only need a few g. Is there any special feature
a salt would need to work for this? Why not just use NaCO3?
I don't mean to say that I don't care about having Ra contamination, TBP is extremely selective for U and some other actinides so even if I had
residual Ra it would be removed at that point.
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j_sum1
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The thing about barium carbonate that is critical here is the Ba2+ ions. Any soluble barium salt would work.
The theory, as explained nicely by phlogiston is that barium sulfate is extremely insoluble. So as soon as sulfate is added, you get a precipitate.
The second critical thing that makes barium suitable is that Ba and Ra are chemically very similar. Which means that any Ra present is likely to be
incorporated into the BaSO4 as it precipitates. Thus you end up with a precipitate that contains all of the radium and which can be filtered out (or
more likely, decanted.)
Do consider how you will dispose of this waste however. Barium is relatively toxic, although it is safest in sulfate since this is quite inert.
Radium is not something to be trifled with. It will replace Ca in any biological systems and release alpha particles at close range within an
organism. Translation, carcinogenic and environmental toxin.
I would carefully collect everything that contains Ba or Ra. I would dilute this with cement and then make a large concrete block with the
appropriate quantities of sand and aggregate. Wear a gas mask and gloves while mixing the concrete: you do not want to inhale any radium. And make
sure you have the right proportions on your concrete so that the block cures to become very hard. Test with a Geiger counter and if the levels are
too high, encase your first concrete block in a second. Dispose as solid waste when fully cured.
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Gammatron
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I will search around more to see if I can find any cheap sources. I recall looking for BaCl a few years ago and find it to be prohibitively expensive
for my needs. But like phlogiston said, Ba tends to occur naturally with U and in the end it really just changes which step in the process it will be
removed.
Any radioactive waste I produce is saved, my whole affinity for U is because it's radioactive and easy to collect the ore but I would be interested in
extracting decay products as well. As for my low grade waste like sands left over from the raw ore I did intend on making into concrete. Everything
else like filter papers is reprocessed.
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Elemental Phosphorus
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Quote: Originally posted by Gammatron  | I will search around more to see if I can find any cheap sources. I recall looking for BaCl a few years ago and find it to be prohibitively expensive
for my needs. But like phlogiston said, Ba tends to occur naturally with U and in the end it really just changes which step in the process it will be
removed.
Any radioactive waste I produce is saved, my whole affinity for U is because it's radioactive and easy to collect the ore but I would be interested in
extracting decay products as well. As for my low grade waste like sands left over from the raw ore I did intend on making into concrete. Everything
else like filter papers is reprocessed. |
While you probably don't need the BaCO3 you can find it for $6 a pound:
https://www.pyrochemsource.com/Barium-Carbonate_p_26.html
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Gammatron
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Wow they got some good prices. Thanks for the tip, I hadn't actually looked anywhere other than Amazon and ebay just because I can usually get free or
cheap shipping.
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Texium
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Pottery supply stores typically sell very cheap barium carbonate too, but it tends to be contaminated with some sulfide and sulfate, so it’s best to
convert it to the chloride or nitrate, filter the solution, and recrystallize to obtain a pure barium salt.
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Gammatron
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Man I just placed a big order at a pottery shop and they even have it in stock really cheap... but you gotta order a lot to make shipping worth it.
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