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Author: Subject: cleaning up radium containing sample somewhat
drspastic
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[*] posted on 16-7-2021 at 00:06
cleaning up radium containing sample somewhat


a couple of years ago i got lots of hot rocks from a tailings pile and made some yellowcake, but had lots of left overs. i put the project aside to let my dose subside.

i now want to clean up one of the leftovers that is undisolved grot from the uranium extraction. it contains pretty much no uranium but is very radioactive so must contain radium and various daughters.
it also is likely to contain salts and remnants of the carbonates, bicarbonates, etc used. possibly quartz and mica.

i am looking for advice on the best steps to take and the best order to work in. obviously the product i am after is in micrograms so neither will i get it pure or likely to seperate actinium from radium etc and thats not a problem. i just want it reduced from around ten grams to less than one without losing the valuble cargo.

my final use for this is making radiographs on xray film. the sample i have darkens film effectively but pictures are very blurry and to fix this i need to concentrate the emitting isotopes into as near to a point source as possible.





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drspastic
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[*] posted on 16-7-2021 at 00:10


https://www.youtube.com/watch?v=zvt_1hbiSFk&t=47s

the stuff in the small black dish is what i need to work on




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The Plutonium Bunny
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[*] posted on 4-8-2021 at 08:06


Cool project! Please post updates here - I'm interested in the results and will hopefully try a small-scale radium extraction myself at some point, when I have appropriate lab space available.

As for your extraction, your next step would probably be alkali fusion with sodium carbonate. From there, you could dissolve everything with HCl and then filter to remove any remaining insolubles.

After that it might be wise to add a bit of a soluble barium or lead salt to act as a carrier. The final step would be adding a touch of sulfuric acid to precipitate the radium along with your carrier of choice. This should concentrate your radium quite considerably, as the list of metals with insoluble sulfates is reasonably small.




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Triflic Acid
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[*] posted on 4-8-2021 at 09:01


Nuetralize, and then just dump it where you found the tailings. The place is radioactive anyways.



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[*] posted on 4-8-2021 at 13:48


I almost agree with the plutonium bunny- carboinate is good but...
A fusion with sodium carbonate will convert silica to silicate and that will reprecipitate as silica gel when you add acid.
The stuff you want may well stick to that gel.

But if you boil the material with a solution of carbonate and then discard the solution you will convert any radium (and most other metals) to carbonates.
You can then wash with water. That will removes a lot of the sulphate ions and also uranium.
You might need to repeat this bit until all the radioactive material dissolves when you do the next step.
The next stage is a leach with excess boiling dilute acetic acid
That will give a solution of the metals as acetates.
You could usefully precipitate the so-called heavy metals as sulphides if you have access to an easy H2S source.


You then have a few options.
Adding sulphuric acid will precipitate the barium (it's pretty much bound to be there as a fission product, even if you didn't add any) and that will carry down the radium.
The trouble is, it will also bring down calcium and that's a much more common component of rocks.

Or you can add a dilution of a dichromate or chromate in acetic acid and that will precipitate barium, but not calcium.

If you don't like the colour, you can treat the precipitated chromate with sulphuric acid solution and a little alcohol to dissolve the Cr and leave BaSO4 with the radium in it.

In case anyone is wondering... I thought it would be interesting to extract the Ra from brazil nuts; I started by ashing the nuts and then followed the process above. I now need a better radiation detector. I should have a few dozen Bq of Ra.

Treating the ashes- still containing a lot of carbon- by just heating then in a closed container at red heat for an hour reduces the sulphates that are present; a leach with carbonate removes the sulphide and leaves carbonates behind- which seems to be more or less where you are starting from

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The Plutonium Bunny
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[*] posted on 5-8-2021 at 17:38


Thanks for the helpful guidance, unionised. I really like your idea about the dichromate use to avoid calcium precipitation - when I wrote my post I wondered how much of an issue calcium would be. Your method will provide a Ra source with higher specific activity.

Also, do post updates about your Brazil nut project! Sounds super cool - maybe a university near you would let you play with their PMT or HPGe gamma detector? I would totally try all this stuff, but I'm about to leave for grad school so I doubt I'll have much time. :P




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[*] posted on 6-8-2021 at 01:43


If I get off my backside and get round to it, I should be able to make use of one of these sorts of things.
https://spark.iop.org/spark-counter#gref

cheap, easy and "blind" to everything but alphas.
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The Plutonium Bunny
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[*] posted on 6-8-2021 at 07:11


Funny you mentioned that - I actually built one a while ago! https://www.youtube.com/watch?v=1jvRzbqR29Y

Definitely fun to play with, and I am sure with proper construction it could be sensitive down to the few dozen Bq. I think the lowest activity I've tried with mine is a 0.9 uCi Am-241 source, but I think that is far above the limit of detection.




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