# Assaying via INAA ? anyone tried ?



## alexxx (Jan 7, 2015)

Hi everybody,

I'm trying to know the complete content of various kinds of boards & electronic scrap.
As you guys know, circuit boards contains a lot of different elements, and some of them may cause specific problems when one would attempt recovery of PMs.

The lab I'm working with suggested an analysis that I never tried before. 45$ per sample.
Neutron Activation Analysis, or more specifically the Instrumental Neutron Activation Analysis. INAA

http://en.wikipedia.org/wiki/Neutron_activation_analysis

The chemist I'm working with mentioned that it is an interesting solution for "exploratory analysis" for a material such as circuit boards.
More pin pointed tests could be conducted after for some specific element, such as fire assay for Au, or Peroxide 8 for Cu.

Here the detection range of the test.
It looks interesting, but the range might not be effective for Cu & Sn.

Ag	0,05 - 10 000 ppm
Al *	0,01 - 50 %
As	0,5 - 100 000 ppm
Au	2 - 30 000 ppb
Ba *	1 - 100 000ppm
Be	0,1 - 1 000 ppm
Bi	0,02 - 10 000 ppm
Br	0,5 - 5 000 ppm
Ca	0,01 - 70 %
Cd	0,1 - 2 000 ppm
Ce *	0,1 - 10 000 ppm
Co	1 - 5 000 ppm
Cr *	1 - 10 000 ppm
Cs	0,05 - 5 000 ppm
*Cu	0,2 - 10 000 ppm*
Dy *	0,1 - 5 000 ppm
Er *	0,1 - 1 000 ppm
Eu *	0,05 - 1 000 ppm
Fe *	0,01 - 70 %
Ga	0,1 - 500 ppm
Gd *	0,1 - 500 ppm
Ge	0,1 - 500 ppm
Hf *	0,1 - 5 000 ppm
Hg	10 - 10 000 ppb
Ho	0,1 - 1 000 ppm
In	0,1 - 100 ppm
Ir	5 - 10 000 ppb
K	0,01 - 10 %
La *	0,5 - 10 000 ppm
Li	0,5 - 10 000 ppm
Lu *	0,1 - 100 ppm
Mg	0,01 - 50 %
Mn	1 - 100 000 ppm
Mo	0,2 - 10 000 ppm
Na	0,01 - 20 %
Nb *	0,1 - 500 ppm
Nd *	0,01 - 10 000 ppm
Ni	0,5 - 100 000 ppm
P	0,001 - 10 %
Pb	0,5 - 5 000 ppm
Pr *	0,1 - 1 000 ppm
Rb	0,2 - 5 000 ppm
Re	0,001 - 100 ppm
S +	0,01 - 20 %
Sb	0,1 - 10 000 ppm
Sc	0,1 - 1000 ppm
Se	0,1 - 10 000 ppm
Sm *	0,1 - 100 ppm
*Sn *	1 - 200 ppm*
Sr	0,2 - 1 000 ppm
Ta *	0,1 - 10 000 ppm
Tb *	0,1 - 5 000 ppm
Te	0,02 - 500 ppm
Th *	0,1 - 10 000 ppm
Ti	0,01 - 10 %
Tl	0,05 - 500 ppm
Tm *	0,1 - 1 000 ppm
U	0,1 - 10 000 ppm
V	1 - 10 000 ppm
W	1 - 10 000 ppm
Y *	0,01 - 10 000 ppm
Yb *	0,1 - 5 000 ppm
Zn	0,5 - 100 000 ppm
Zr *	1 - 5 000 ppm

Any toughs ? Any recommendation ? Anyone tried this kind of analysis ?

cheers,

Alex


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## Lou (Jan 7, 2015)

Again, like I so often say (being an analyst)...CONTEXT.

NAA is a great, robust technique in the right context with a huge linear range. 

Alexx, you're after everything but the squeal. Nothing wrong with that, just understand that theory and practice are two different things entirely. 

Can you send a single circuit board in and get a spot analysis via NAA? Sure. I think it's worth very little data-wise. 

Your best bet might be shredding and pulverising the boards, sampling, then sending for capsulization and NAA. Even then, you'll have different fractions that sieve out each needing their own analysis. Copper might be too high and off charts. 

Fire assay won't give you much in the way of base metals--that's the objective, to remove all of the stuff that oxidizes. Unfortunately, you lose Cu, In, and most other non-noble metals into the slag. 

Try and combinatorial approach--fire assay for precious metals, NAA for the slag 

Lou


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## alexxx (Jan 7, 2015)

Lou said:


> Your best bet might be shredding and pulverising the boards, sampling, then sending for capsulization and NAA.
> 
> Try and combinatorial approach--fire assay for precious metals, NAA for the slag
> 
> Lou



That's exactly where I'm at now.

Lou, besides Cu, Sn & Pms, any other element I should look for with a different specific test to get a hold of the whole picture ?

cheers,

Alex


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## necromancer (Jan 7, 2015)

in your original post the Ta reading was a good measurement. it's may worth getting it out if you can.
Ta *	0,1 - 10 000 ppm, that's equal to the silver content.


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## goldsilverpro (Jan 7, 2015)

The most difficult part is sampling the non-homogeneous shredded material. How do you pull a set of samples from this material that is representative of the entire lot? Remember that an assay only determines the values in the sample(s) you've provided. One sample and one assay is never enough, no matter what you are assaying. The more non-homogeneous the material and the larger the lot, the more samples (and assays) needed.

If the whole lot of boards are of the same purpose and all come from the same manufacturer, I had better luck fire assaying the gold-bearing components individually and then noting the count of these components on the boards.


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