# Video About Using Oxalic Acid



## kadriver (Oct 29, 2012)

Hello:

I used oxalic acid for the third time last night to make another nice pure bar (see photos)

I also made a video that demonstrates the technique that I am using to do the oxalic acid precipitation;

[youtube]http://www.youtube.com/watch?v=o165tgxFMYM&feature=plcp[/youtube]

It is all new to me. Any input on how I could do anything differently or improve my technique would be appreciated.

kadriver

Edit once to insert the video


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## eeTHr (Oct 30, 2012)

All I can say is "wow!"

...and thanks very much for posting the information from your experiments, and the video!


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## grance (Oct 30, 2012)

Very nice never tryed it but maybe I will now


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## chemdom (Oct 30, 2012)

Nice piece of gold, well done. And also thank you for posting the video, it's nice to see the set up that each individual uses.
I am spoiled that I work in a chemical lab.


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## goldenchild (Oct 30, 2012)

The only criticism I have is to please add a warning on your thread topic. Something like "Video About Using Oxalic Acid (wear sunglasses)". It's early in the morning here and it hurt my eyes opening up this thread and looking at that bright @$$ bar.


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## HAuCl4 (Oct 30, 2012)

The best last rinse (for maximum purity) for oxalate dropped gold is with boiling concentrated nitric acid. (Make sure the hydrochloric acid is gone completely before the nitric acid rinse). And please do not touch high purity gold with greasy hands!. Use surgical gloves. Nice video. 8)

Some people have reported better results adding the gold solution dropwise into the boiling oxalate solution. Apparently the gold crystals grow bigger and purer that way.

Next time use a bigger beaker. That was close for a spill. Perhaps that's why "adding the gold solution dropwise into the boiling oxalate solution" was recommended to me long time ago?. Who knows?. :shock:


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## AlZabrisky (Oct 30, 2012)

Very good work and result.
Constant stirring reduces reaction time.


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## kadriver (Oct 30, 2012)

Thank you for all your comments and suggestions.

I took the bar made in the video to the refiner today, here is a photo scan of the statement.

99.95% pure gold - I finally made it to the industry standad.

Thanks for looking.

kadriver


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## element47.5 (Oct 30, 2012)

You do a great job on your videos, ka!


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## Lou (Oct 30, 2012)

Please do not be offended, but the gold made from oxalic isn't to be measured by EDXRF.

It is better than that.


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## Palladium (Oct 30, 2012)

I'm with Lou on this one. That gold is better than 995.


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## kadriver (Oct 31, 2012)

I believe you guys - the folks at NTR don't know any better.

They just follow company procedure - I don't think they even have any refining experience, other than melting and shooting the xray gun at a sample.

They are vey pleasant people to work with, its convenient, and I don't mind paying their fees to get paid on the spot.

There was melt loss on this statement - I wonder what would happen if I asked for the crucible after the melt to recover any gold that stuck to it?

kadriver


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## Palladium (Oct 31, 2012)

They actually melted it! They never melt mine at NTR just shoot it and go with it.


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## kadriver (Oct 31, 2012)

I asked what they did once I turned it over to them.

They said that they analyze it with XRF as it is, then again after it is melted and compare the two readings.

I wonder if they just threw this nice gold bar in with the rest of the karat scrap for the day?

I turned in a second bar that same day made from karat scrap purchased the previous evening. It was about the same weight - it had been inquarted, boiled in dilute nitric, rinsed, boiled in HCl, rinsed and dried and melted - took about 2 hours to complete. It was assayed at 998.

The 9995 bar took me about 10 or 12 hours to complete and much more chemicals. The only reason I did not run the second bar through the entire process was lack of time.

From now on, if I have the time I intend to keep practicing with the oxalic acid to continually improve my technique and produce the purest gold that I can.

Kadriver

Edit one time to add refining statement and correct some grammar
Edit a second time to add a procedural step that had been left out in the original post


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## goldenchild (Oct 31, 2012)

I wonder what would happen if you sent them a known .9999 bar. Like from kitco or apmex.


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## kadriver (Oct 31, 2012)

I thought about getting a 1/10 ozt maple leaf and asking them to use it as a comparison standard for one of these pure bars.

But who knows, the maple leaf could be off - or could it?


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## g_axelsson (Oct 31, 2012)

I think you should ask what the precision of the XRF is, or what model it is and search for the data sheets of it online. Common knowledge among microscopists is that EDS (the way to measure the spectra from the sample) have an error of 0.1%.
I wouldn't be surprised if the span of measurement (measured value +/- maximum error) would go beyound 100%.

One way to get a lower reading than the real value is to have surface contaminants, XRF measure is affected very much by the surface condition. If there are small traces of copper in the melting dish that NTR is using it could be picked up by the melt and contaminate the surface of the remelted gold with copper oxide.

As for the melt loss, the measurement before and after melt is only measured with three significant digits but on the pay out the weight is measured with four. The difference beween 26.3 and 26.4 could be a lot less than 0.1, for example 26.3499 and 26.3501 would be rounded off to 26.3 respective 26.4 but the difference is only 0.0002.
Maybe they practice to always round off upwards on before melt and downwards after melt.
Check your old refining statements and if there is constantly a 0.1 difference on high purity gold then I would ask them why the weight difference is larger than the amount of impurities before melt.

/Göran


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## kadriver (Nov 1, 2012)

g_axelsson said:


> I think you should ask what the precision of the XRF is, or what model it is and search for the data sheets of it online. Common knowledge among microscopists is that EDS (the way to measure the spectra from the sample) have an error of 0.1%.
> I wouldn't be surprised if the span of measurement (measured value +/- maximum error) would go beyound 100%.
> 
> One way to get a lower reading than the real value is to have surface contaminants, XRF measure is affected very much by the surface condition. If there are small traces of copper in the melting dish that NTR is using it could be picked up by the melt and contaminate the surface of the remelted gold with copper oxide.
> ...



Great info, I asked if they were going to use a new crucible to do the melt and they said yes. But they may just thrown it in a used crucible that, "looks OK'", and then do the melt.

Thank you for the input concerning the numbers. In the past, there has never been a melt loss on any of my statements. The number before and after melt was always the same.

But there was a new guy (probably sent there to inspect their ops by the corporate office) and this time there was a melt loss.

kadriver


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## samuel-a (Nov 2, 2012)

Hi Kev

I posted the video.


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## qst42know (Nov 3, 2012)

It appears NTR knows you won't bleed to death from small cuts.


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## kadriver (Nov 4, 2012)

Samuel - great video, I posted a comment on the youtube site and gave it a thumbs-up.


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