XRF assay, or how I threw away $35 but found $500,000 in the process

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  • Last Post 10 October 2015
mtngun posted this 25 September 2015

Palladium (Pd) sells for $650 per ounce, so apparently my 55 pounds of reclaimed shot are worth $500,000.    :D  :D  :D Seriously, whatever this reclaimed shot is, it's good stuff.   It casts well and heat treats to BHN 40.   That's right, 40, and I have confidence in that measurement, unlike the assay.  :D

I sent off a sample to be assayed, because I wanted to be able to duplicate this alloy on command.   Obviously reclaimed shot is not a controlled alloy so the next time I buy reclaimed shot it may be different than this batch.    But I guess the recipe will remain a secret. :(

The seller, Rotometals, said it typically runs 3% - 4% antimony on their XRF.   Their XRF does not measure arsenic, so they couldn't say about the arsenic content.   

I knew going into this that XRF's were fallible.   I just didn't realize how fallible.  :D  :D  :D

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Wineman posted this 26 September 2015

Probably a typo that should say Pb not Pd. Since the lead line is right above palladium, it is an honest mistake :-).

Dave

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mtngun posted this 26 September 2015

Update: the assay guy confirmed that it should be Pb not Pd. I guess I don't have $500,000 worth of ingots, after all. :D

Of course I was more interested in the other ingredients. I KNOW there is arsenic in shot, but apparently XRF has a tough time picking up arsenic.

I'm skeptical that there is Iridium. It's a very rare element.

Aluminum in lead shot?

Phoshorus is interesting, it's close to the other grain refiners like arsenic, selenium, and sulphur, and I had been wondering if phosphorus could be used as a substitute for arsenic. And silicon is in that group, too.

All in all the assay is worthless.

But ... the density of the alloy suggests that it is only about 91% - 92% lead, so there's gotta be SOMETHING in it besides the expected 3% or so antimony. I wish I knew what.

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gpidaho posted this 27 September 2015

Good morning Guys: For you that don't follow on “Boolits” there is a fellow member there, BNE that will run Xrf tests on your alloy in exchange for any lead alloy. 1lb. lead= 1 test. Sounds more than fair to me. Gp

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mtngun posted this 27 September 2015

gpidaho wrote: Good morning Guys: For you that don't follow on “Boolits” there is a fellow member there, BNE that will run Xrf tests on your alloy in exchange for any lead alloy. 1lb. lead= 1 test. Sounds more than fair to me. GpThanks for the tip, gpidaho.    Yes, that is a bargain though I dunno if his XRF is any better than the one I used.   

There was a thread or two on Boolits showing XRF's of wheelweight and claiming to “prove” there was no arsenic in wheelweight because the XRF said so.      I rolled my eyes.   :thinking:

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mtngun posted this 10 October 2015

Measuring the indentation of an oven treated (480F)  sample  of reclaimed shot after 1 month of aging, using a a USB microscope to see the tiny indentation.    The calipers were locked on 0.080", 7.9375 mm ball (5/16” diameter), 150.6 kg load for applied for 30 seconds.   46 BHN.      :shock:

Now whether it shoots any better than a less hard alloy, I don't know.   Much testing will be required to answer that question.     Hopefully it will eventually result in a TFS article.   

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