Everything (hopefully) you ever wanted to know about XRF

[GuyGuyGuythe1st]

Interesting perspective on the topic, but it is not the density that do the separation is it?
Except for the elements that is too light to reflect any of the X-rays.

It's the returned spectrum from the outgoing X-rays.
It is the X-rays that excite electrons in the outer shell of the elements and when they fall back to the original position they send out an photon with an energy in a certain frequency.
The receiver picks these up and estimates what is in the material being radiated based on libraries and algorithms.
Libraries to tell which spectrum belongs to which element and algorithms to estimate the amount of said element.
The operator have to make sure it is done in the proper way to get consistent reading and make sure the proper library are loaded for the test at work.
I'm sure there is a plethora of things I have not said and maybe some exaggerations.
But in short that is how I understand it.

Please do correct me if I'm wrong.

You are correct. I wasn't breaking it down that far. I was generalizing the science.

 

[EMRE]

I get screen shots of XRF readings from clients all the time just like the one below. This lot in particular represented a bar which was about 270 ounces. Sure he wanted the Gold and Palladium but the Rhodium is what be wanted most. Even though the percentage is small, the $18000 an ounce made him drool for it.

I told him to aqua regia refine it and cement out the PM’s after the gold by Sulfur Dioxide and the Palladium by Ammonium chloride and sodium chlorate. Then, when he collects enough from the cementation tank to talk about that process. He really didn’t want to hear that it likely doesn’t have Rhodium anyway.

What do the sigma values represent to some of our XRF experienced members. What can they tell you about this bar?

4Metals,

what i can tell from the color of that device, it is a niton xl2 handheld and we have two of them for the last ten years. At the reading levels in the picture Pt and Rh may not even actually exist and Pt may very well have 30-50% margin for error. I would also keep in mind that Au, Ag, and Pd may have 2-5% deviation too. These machines are usually great if they are calibrated well for carat gold between 50-60% range. Deviation worsens on higher or lower concentrations. Stirling silver usually reads around 94%, and 830 silver reads around 88% on our devices because the beam source has some sort of silver rich part so returning waves are reading higher. Best way is probably pay for icp on all metals. We got burned few times when customer wanted to get paid on gold and platinum and we settled based on xrf readings. unfortunately bars were not big enough to pay $400 assay fee on all metals..
regards.

 

[Pacin]

I have a question, I have few types of material with have very similar behawior to Rhodium like melting point, chemical resistance, catalitic abolitys etc. but XRF shows mostly Cu rader Fe, Ni, Co. It is posible that XRF can't recognized it if Rhodium is in catalitic form (even in alloyed bead)

 

[Pacin]

I have a question, I have few types of material with have very similar behawior to Rhodium like melting point, chemical resistance, catalitic abolitys etc. but XRF shows mostly Cu rader Fe, Ni, Co. It is posible that XRF can't recognized it if Rhodium is in catalitic form (even in alloyed bead)

 

[Cambridge Environmental]

A quick question about XRF sample prep scales and dispensers, generally how much do they cost?

 

[muserfish]

Dear all,
I have recently bought an XRF (Niton XLT 793KWZ), its quite an old model but still in great working condition.
Having said that, DUE TO it being an older model I do not have its software or ay way to get to its firmware.
Thought this would be a decent place to ask for direction. I tried Thermo Scientific themselves but they washed their hands faster than Pontius.

 

[4metals]

Just like computers some of the instruments outlive their "upgradeable" life. Capitalism at its finest. What you can do is acquire calibration standards and see how the unit performs against a known commodity.

 

[muserfish]

Just like computers some of the instruments outlive their "upgradeable" life. Capitalism at its finest. What you can do is acquire calibration standards and see how the unit performs against a known commodity.

Thanks 4metals!
I failed to mention that it does detect around 20 metals as is and has just some features diabled. Perhaps with a Niton Data Transfer or something like that I could either download the data and analyse it on my PC or else unlock the missing features to be able to detect Au and Al. The device is definitely capable of that (detects Au, Pd, Ni, Cu etc already). That would be very convenient, for I deal with electronics scrap (plenty of Al)

 

[goldandsilver123]

Thanks 4metals!
I failed to mention that it does detect around 20 metals as is and has just some features diabled. Perhaps with a Niton Data Transfer or something like that I could either download the data and analyse it on my PC or else unlock the missing features to be able to detect Au and Al. The device is definitely capable of that (detects Au, Pd, Ni, Cu etc already). That would be very convenient, for I deal with electronics scrap (plenty of Al)

Al is hard for handheld xrf to analyse, the element is very light (few protons). I know that mine xrf does not show Al, and you cannot see it's peak in the spectrum

 

[muserfish]

Al is hard for handheld xrf to analyse, the element is very light (few protons). I know that mine xrf does not show Al, and you cannot see it's peak in the spectrum

That would make a lot of sense.
I am just frustrated that the mother company has utterly refused to have anything to do with it.
I cant even get hold of the Data Transfer utility. So I am stuck with 1 mode and just screen readings. But hey, I at least managed to make it work and see some the light of day once again.

 

[hoytSmith]

If it helps…

An XRF gun emits a stream of high-energy photons. These photons have a probability of exciting electrons in some valence shells of atoms. The amount of energy absorbed by this excitation is released as a photon when the excited atom returns to a lower energy states. Emission profiles are compared with data stored in memory.

Quantum physics dictates that the photons emitted by the sample will correlate to a predictable spectrum of energy. As a hypothetical: a hydrogen electron has a couple of excited states. A reflected beam will contain photons emitted by the excited hydrogen. Add some sodium and you get some more (different energy) photons. If that’s all there is, you get a spectrum with 6-8 wavelengths in proportion to the ratio of photons given off by hydrogen atoms and sodium atoms. There’s a lot of linear algebra required to sample just a few elements, so libraries of common elements of interest are used to interpret results and those libraries vary with materials sampled. If an atom is in a molecule, the emission spectrum will be different.

Use the wrong library, results are worse than useless. Include elements not in the library, but with similar emissive properties and misidentification is likely. I would use great care before using xrf as a quantitative instrument. I would not rely on xrf as proof of the absence of anything (like arsenic) without knowing that the machine is calibrated to detect it.

As others have said — it’s a good tool for confirming what you think you know and discovering that something isn’t what you expected. Also, even high-energy photons won’t get very far in a sold metal, the results are correlated to the first few microns of a solid metallic sample — so it’s really not good for assessing something for sale from an untrusted source.

So: great screening tool — but don’t bet (much) money or you health on the results of a handheld gun.

 

[4metals]

Unfortunately, many refiners have bought the Niton hand held and use it without annual calibration as if it is the word of God. (If God of course is speaking in their favor)

 

[orvi]

Unfortunately, many refiners have bought the Niton hand held and use it without annual calibration as if it is the word of God. (If God of course is speaking in their favor)

We had one old Niton XRF back in my refining days. Very old machine, never callibrated from the moment my partner bought it for like 3-4k. It was good informative tool in the lab, measuring slags for metallic inclusions of PMs, unknown solids/liquids just to get informative results on what is probably in there... But aside of that, it was so so off when measuring even the known stuff (like 52% Au on veryfied 14k), that it was unusable for much else.
As you correctly said, many people out there take the results as firm reality... And that breed a lot of confusion. Similar with famous "yellow" machines One thing is the sigma value machine gave you, other is if it was callibrated in past 5 years...

I used to buy stuff from folks at scrapyard that had some old wanky XRF, and I always bring some standard alloys of silver and gold with me. Their confused faces were unforgettable
Some didn´t trust my "alloys", so I said that guys, I see you wearing silver chains and gold rings... Shot them with the machine instead. After that, confusion raised

 

[muserfish]

Merry Xmas to all!
I'm happy to announce that I managed to steal the accompanying software for my XRF. Calibrated it, and tested it on a known ring of mine.
Pretty accurate for my purposes, at least. I first XRF'd the surface I am going to operate on, then XRF'd with the thingy on it.
Results of the Spectral Difference attached. Happy me! Thanks a lot for your help guys, you're a wealth of knowledge for all of us newbies.
Obviously, those are the L lines you see for gold. K lines are too far to the right hand side for a Si-pin.

 

[Yggdrasil]

Merry Xmas to all!
I'm happy to announce that I managed to steal the accompanying software for my XRF. Calibrated it, and tested it on a known ring of mine.
Pretty accurate for my purposes, at least. I first XRF'd the surface I am going to operate on, then XRF'd with the thingy on it.
Results of the Spectral Difference attached. Happy me! Thanks a lot for your help guys, you're a wealth of knowledge for all of us newbies.
Obviously, those are the L lines you see for gold. K lines are too far to the right hand side for a Si-pin.

I cincerly hope you did not steal the software.
We do not support criminal behaviour in here.

 

[goldandsilver123]

Merry Xmas to all!
I'm happy to announce that I managed to steal the accompanying software for my XRF. Calibrated it, and tested it on a known ring of mine.
Pretty accurate for my purposes, at least. I first XRF'd the surface I am going to operate on, then XRF'd with the thingy on it.
Results of the Spectral Difference attached. Happy me! Thanks a lot for your help guys, you're a wealth of knowledge for all of us newbies.
Obviously, those are the L lines you see for gold. K lines are too far to the right hand side for a Si-pin.

K-Lines for gold need higher voltages, normally handheld are 45 - 50 kV. There's no way the K-Lines for gold are emitted.

You should increase your measurement time with the piece and xrf standing still, the background can be smoother. Around 30 seconds for metal alloy

Also your ring has cubic zirconia as gem.

The peaks are low on cps for gold, that could be your spectrometer or you did analyse just a small part or it was far away from the "window".

 

[muserfish]

I cincerly hope you did not steal the software.
We do not support criminal behaviour in here.

hahaha apologies for the bad use of language.
They are readily available to customers (if they have serial number) on their website: Welcome to Product Support for Portable Analyzers | Portable Analysis for Material ID
apologies again

 

[muserfish]

K-Lines for gold need higher voltages, normally handheld are 45 - 50 kV. There's no way the K-Lines for gold are emitted.

You should increase your measurement time with the piece and xrf standing still, the background can be smoother. Around 30 seconds for metal alloy

Also your ring has cubic zirconia as gem.

The peaks are low on cps for gold, that could be your spectrometer or you did analyse just a small part or it was far away from the "window".

Thank you very much. Quite insightful. Ill test again with your suggestions.
Regarding the Zirconia, I was pretty amazed it can pin point it so quickly, considering THAT was actually "far" from the window. Ah yes, perhaps I was pointing at a thin part of the ring, its not exactly what I would call a flat surface.

 

[GuyGuyGuythe1st]

Interesting perspective on the topic, but it is not the density that do the separation is it?
Except for the elements that is too light to reflect any of the X-rays.

It's the returned spectrum from the outgoing X-rays.
It is the X-rays that excite electrons in the outer shell of the elements and when they fall back to the original position they send out an photon with an energy in a certain frequency.
The receiver picks these up and estimates what is in the material being radiated based on libraries and algorithms.
Libraries to tell which spectrum belongs to which element and algorithms to estimate the amount of said element.
The operator have to make sure it is done in the proper way to get consistent reading and make sure the proper library are loaded for the test at work.
I'm sure there is a plethora of things I have not said and maybe some exaggerations.
But in short that is how I understand it.

Please do correct me if I'm wrong.

Yes the targeted “element” is hit with an Alpha, Beta or Gamma ray depending on the type of test and element to be tested. The excitement of the bombardment is measured back into a filter. Which then computes it into an element %. The alloy recipe and element % are defined in various alloy specifications. To create a specific alloy type.

You can also buy known “Alloy Standards” which allows you to calibrate your machine prior to testing.

Example: http://www.xrfresearch.com/xrf-certified-standard-alloys/

 

[Yggdrasil]

Yes the targeted “element” is hit with an Alpha, Beta or Gamma ray depending on the type of test and element to be tested. The excitement of the bombardment is measured back into a filter. Which then computes it into an element %. The alloy recipe and element % are defined in various alloy specifications. To create a specific alloy type.

You can also buy known “Alloy Standards” which allows you to calibrate your machine prior to testing.

Example: http://www.xrfresearch.com/xrf-certified-standard-alloys/

It is still not the density, but the exited electrons from the different shells and the energy they release in reaction to the incoming energy from the source.
One can say that there is a certain correlation between the density and the electron shells. But it still is not the density that are read.