XRF Iridium/Arsenic

[Julia Burlingham]

Hi again,

I originally used an XRF machine to test a 2lb chunk of hard mining concentrate. It showed 35% iridium. Thanks to this group I found that it was most likely arsenic. So I had a ICP test done with American Analytical Services to test for Arsenic. That was way cheaper than testing for iridium and I figured if it comes back as 35% then I'll know there is no Iridium. It came back as 5.64% arsenic. Is there something else that the other 29% could be besides Iridium? I'm going to test for Iridium next, but I wanted to ask you guys because you're obviously very knowledgeable.

Thanks!

Julia

 

[Yggdrasil]

Hi again,

I originally used an XRF machine to test a 2lb chunk of hard mining concentrate. It showed 35% iridium. Thanks to this group I found that it was most likely arsenic. So I had a ICP test done with American Analytical Services to test for Arsenic. That was way cheaper than testing for iridium and I figured if it comes back as 35% then I'll know there is no Iridium. It came back as 5.64% arsenic. Is there something else that the other 29% could be besides Iridium? I'm going to test for Iridium next, but I wanted to ask you guys because you're obviously very knowledgeable.

Thanks!

Julia

Any ore containing more than 0. something percent Iridium is unheard of.
Where did you perform the XRF test and in what mode was it?

 

[Julia Burlingham]

Any ore containing more than 0. something percent Iridium is unheard of.
Where did you perform the XRF test and in what mode was it?

Thank you so much for your reply. I took it to two different pawn shops with different machines. I don't know what mode it was on, but here are some pictures that might help.

 

[goldshark]

Hi again,

I originally used an XRF machine to test a 2lb chunk of hard mining concentrate. It showed 35% iridium. Thanks to this group I found that it was most likely arsenic. So I had a ICP test done with American Analytical Services to test for Arsenic. That was way cheaper than testing for iridium and I figured if it comes back as 35% then I'll know there is no Iridium. It came back as 5.64% arsenic. Is there something else that the other 29% could be besides Iridium? I'm going to test for Iridium next, but I wanted to ask you guys because you're obviously very knowledgeable.

Thanks!

Julia

Mining concentrates usually are in powder form, although it does occasionally clump together. Do you have a picture of the chunk?

 

[Julia Burlingham]

Hi Goldshark. This was from the bottom of a concrete bin where they dumped their concentrate for 30 years.. The loader would dump everything in the bin before sending it to the smelter. The stuff on the bottom accumulated.

 

[Yggdrasil]

Thank you so much for your reply. I took it to two different pawn shops with different machines. I don't know what mode it was on, but here are some pictures that might help.

The XRF is in precious metals mode and will interpret what it do not have in the library as something it has in the library.
Which is PMs like Gold Silver and the PGMs.

 

[Julia Burlingham]

The XRF is in precious metals mode and will interpret what it do not have in the library as something it has in the library.
Which is PMs like Gold Silver and the PGMs.

I also tested gold and silver. Here are the results

 

[goldandsilver123]

X-Ray Fluorescence yield is different between elements. K lines of Arsenic has higher yield than Iridium L lines. The software compensates this with and many more variables, like sample volume that is emitting fluorescence xrays.

35% in XRF on a mismatched element, on a different matrix will not correlate in 35% in reality.

 

[Julia Burlingham]

X-Ray Fluorescence yield is different between elements. K lines of Arsenic has higher yield than Iridium L lines. The software compensates this with and many more variables, like sample volume that is emitting fluorescence xrays.

35% in XRF on a mismatched element, on a different matrix will not correlate in 35% in reality.

Thank you for explaining that. Do you think it's worth doing the specific iridium test?

 

[goldandsilver123]

Thank you for explaining that. Do you think it's worth doing the specific iridium test?

Ask for the spectrum, iridium La line is almost the same intensity as Lb line.

But if it has ~5% Arsenic that explain the xrf reading and should be no Ir

I do not know about mineralogy, if As presence can indicate presence of Ir.

Every sample with As I read in my WDX didn't had Ir.

 

[Julia Burlingham]

Thank you! What is WDX?

 

[goldandsilver123]

Thank you! What is WDX?

It's a type of XRF, where there's more resolution on the spectrum (~50 eV) than EDX ( ~150eV).

Wavelenght dispersive x ray fluorescence spectrometer - WDX

Energy dispersive x ray fluorescence spectrometer- EDX

Both can be in electron microscopes but then they are normally called EDS and WDS

 

[Julia Burlingham]

It's a type of XRF, where there's more resolution on the spectrum (~50 eV) than EDX ( ~150eV).

Wavelenght dispersive x ray fluorescence spectrometer - WDX

Energy dispersive x ray fluorescence spectrometer- EDX

Both can be in electron microscopes but then they are normally called EDS and WDS

Thank you for explaining that!

 

[Hurc]

Hi
What about gold as ICP test indicate its precense. Will it be in sulfide form?
Thanks

 

[goldshark]

The ICP will quantitatively read the Gold, regardless of whatever form it is in. The mill owners probably had a Gold circuit, to remove any free Gold. This reduces theft in transport, as well as any other potential areas of theft. This is merely a speculation, as the assay levels for the Au are not high in the report, and we have no idea what the head ore ran in Au.

 

[goldshark]

Hi
What about gold as ICP test indicate its precense. Will it be in sulfide form?
Thanks

I have seen ores where the Au can be removed, leaving a relatively poor Au level in the concentrate. If the concentrated sulfides are in a high enough quantity, they are shipped to a facility for conversion into Sulphuric acid. Seen a lot of sulphide ores with floatable free Au, almost no Au in the sulfide concentrate.

 

[SRM]

Hi Julia!

If it were me, I would contact Daniel at AA and ask him if there was enough pulp reject to run 32 element ICP. He can also tell you the current cost. Sometimes it is easier to define all of the plentiful, easier analyzed elements to see if there is something else to investigate.

SRM

 

[markscomp]

Daniel at AA?

 

[Yggdrasil]

Hi Julia!

If it were me, I would contact Daniel at AA and ask him if there was enough pulp reject to run 32 element ICP. He can also tell you the current cost. Sometimes it is easier to define all of the plentiful, easier analyzed elements to see if there is something else to investigate.

SRM

Since our mind reading module is broken, could you please elaborate what AA is?

 

[SRM]

Sorry, Daniel is the lab manager for American Analytical, the lab that did Julia's fire assay.

SRM