# Identifying Assay Machine



## mattafc (May 8, 2011)

After about 57 seconds of this video the drillings from a gold bar are put into a machine which returns an assay result.

Does anyone know what the machine is, who its made by or a company that makes a similar one?

http://www.youtube.com/watch?v=cIBTX2C1FQE

Many thanks


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## Fournines (May 8, 2011)

http://tinyurl.com/3d4qtxf


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## mattafc (May 8, 2011)

Is that an XRF? I've used the handgun but it wasnt obvious from the video that that's what is was


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## jimdoc (May 8, 2011)

If you post a link to the video it may help.

Jim


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## mattafc (May 8, 2011)

http://www.youtube.com/watch?v=cIBTX2C1FQE

Sorry guys, its about 56 seconds in


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## nevadatime (Jun 29, 2011)

They are using a ElvaX mini
Si-PIN detector

It's an ok unit but I think there are better units out there and for less money. This one costs near $30k.


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## mattafc (Jun 29, 2011)

nevadatime said:


> It's an ok unit but I think there are better units out there and for less money. This one costs near $30k.



Do you have a view on what a better one would be? I'm viewing a demo on a skyray 3000 next week


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## Oz (Jun 29, 2011)

Mattafc, 

This will sound harsh, but I am only looking out for you, and you spending your money wisely. In your other posts you are looking for a furnace recommendation as well as crucible recommendations. This leads me to believe you have not even cast precious metals before, and yet you are ready to spend $30,000.00 and up for one piece of testing equipment.

If my written assumptions are correct, have you lost your mind?

I know everyone talks about XRF and ICP like they are top analytical equipment, and they are. Truth be told however, their accuracy is completely (extremely) dependent on your skill in its operation and your level of experience with it. 

If you have money to burn, great! If not, learn the basics first. 

It may help if we knew whether you were trying to check purity in order to buy (non-destructively), or just checking your purity going out the door after you have refined. If it is the later, there are far less expensive ways to determine the purity of the metals you are refining than XRF.


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## mattafc (Jun 29, 2011)

Thanks Oz and I appreciate your frank and honest feedback. The machine will be used to test material going out the door, prior to refining. This will be after melting carat jewellery. Pin samples from this are to be assessed on XRF. I have seen. Proportional counter XRF demo'ed and it doesn't meet the required usage. This is why I'm looking at silicon pin detectors which I think might do what we need. I understand silicon drift detectors to be at a much higher cost.

Having said this, my knowledge is limited on XRF, and am here to learn, so anything you can help with would be greatly appreciated.


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## Oz (Jun 29, 2011)

Well I would be the wrong one to advise you on the high end testing equipment as I do not use it, Lou or 4metals would probably be best for that. 

Some things to consider if you found XRF too inaccurate though. If you are melting karat scrap to bar and testing pin samples taken at the time of pouring there will be inaccuracies built into the bar. Typically you will have gemstones and bits of stainless steel that make up part of your bars mass, but are not molten into the bar in a homogeneous manner, so they will not be accurately represented in your pin samples. So unless you can be assured no stainless or stones are in your scrap, even the most accurate testing equipment and operator will still just give you a close approximation of gold content. 

Only you can answer the question if the expense of such equipment is cost effective for you given the above. If I was in your position and needing to know gold content on a mixed lot karat scrap bar without refining it, I would opt for fire assaying drillings from the bar. It is far less costly and just as accurate in this case. One man’s opinion. 

It is worth noting that XRF results are often confirmed by a fire assay.


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## mattafc (Jun 29, 2011)

Thanks Oz. Most of the gemstones and stainless steel would be removed by hand prior to melting and additional impurities separated through the use of borax. My intention is to to assess a pin sample in three places to try to combat the possibility of an unhomogenous melt (if that is a word!) but my understanding is that induction melting is the best method to achieve a constant through the molton mix. Although I understand that fire assay is potentially more accurate, my belief is that it's only as good as the person undertaking the assay and therefore error prone. I also understand that I can get a small margin of error from XRF (enough for what I need) by having curves developed specifically for my application. The skyray 3000 is my preferred option at the moment but if you have an opinion as a more experienced user than me I'd love to hear it. My knowledge base is process engineering so understand well the capabilities and tolerances I need but need to build knowledge on the technology and limitations of technology before I commit to spend.


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## 4metals (Jun 29, 2011)

This is the machine you are looking at in the video.


I know some refiners who use this machine and are having problems with drifting of results. 
I have seen better results using a Niton unit which can be used as a hand-held or in a holder to make the unit function as a table top unit.




However, if you are using the XRF to read your composite melts for shipping and nothing else, then it will be far cheaper to set up to fire assay. If you plan to buy from XRF results than the speed is what you need.

As far as making a bar with consistency throughout, using induction and a good stir before you pour, you shouldn't have a problem. Bars with a few percent nickel content and a few percent PGM content as well have been known to read unreliably. In that case, can't beat a good old fire assay.


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