Repurification of a Pure Gold Button - VIDEO

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kadriver

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Oct 25, 2010
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I was in such a hurry to get the jeweler's mat finished, after working on it for two weeks, that I only did a single refining.

Plus, I FORGOT to add a little sulfuric acid to get any lead out before filtering.

So I did a quick repurification today before I give the gold back to him tomorrow. I did this to ensure high purity for the jeweler.

Thanks for pointing it out Smack!

https://youtu.be/WFwWM-T6WHw

kadriver
 
Like so many, I love your videos. I have a couple of pseudo-critical comments, which are offered only because you are open enough to invite them. Please understand they are offered respectfully, humbly and from a position of relative inexperience. I myself am still slowly collecting powders and have never even made a melt of gold. (I'm still only up to playing with copper and propane.)

Your gold powder looked a tad dark to me, even wet. I think I'd be wanting more for a cinnamon colour.

It appears to me, in this video at 7:00 and in others, that you almost dump in copious quantities of SMB; or at least more than enough for the job. I wonder if this may contribute to unwanted drag-down. I've been struggling for weeks with the study of the science of SMB and SO2 and co-precipitation. But I have a feeling that adding "just enough" incrementally as per your nitric may be of benefit to purity, especially when it comes to unwanted drag down, such as copper. Though a jeweller may not care about copper.
 
I didn't get to see the filter after but I noticed a color change after the addition of sulfuric, so did you get a precipitate? Also, how come you didn't do the HCL, Hot Water and Ammonia washes? That being a jewelers mat, wouldn't there be the possibility of Pt. or Pd. in the lot? And so doing the washes with the Ammonia to help clean up any Pt or Pd? Another question, and trust me, I'm not riding you here, I love your work in the videos you make for everyone to see but I was shocked when you dumped that gold into the beaker whole and didn't shot it first. I was like "Oh shiznit, that's gonna take forever", but you probably had other stuff to work on while it digested.

Oh, one more thing after it's been a minute since you processed that. Could that which was giving you trouble in the beginning have been Copper (I)? I'll go back and read I think it was Mario's post from the second video where he had some ideas and if he had Copper (I) in there I will edit this paragraph.

Nope, sorry it was Göran that was talking about it possibly being Calcium. I was reading something from Lou recently that was connected to washing technique or working with jewelers sweeps or something along that line and I'm sure he had copper (I) as being problematic. Sorry I have a hard time remembering things I've read, I get bits of info from different things I've read crossing. Numbers are easy.
 
Kadriver

A great video. A few hopefully helpful and constructive comments if I might.

1. Shot your gold before redissolving it. It takes far less time to digest because of the vastly increased surface area. Personally I never melt gold unless it's been through both a recovery drop and a refine but I guess that's more down to personal choice.

2. The comments made about drag down are valid. If you are dumping everything out with excess SMB then a lot of the copper impurity is being pulled straight back out into your powder. On a re-refine like yours I add precipitant and decant the solution off before approaching the last part of the drop. My gold is a pale sand colour. Then I finish the drop in another vessel and keep that gold separate as it will not be as pure as the first part of the drop. If you're doing a job for someone you can add a known quantity of your own pure gold (possibly a few grammes) to the initial AR so you'll always end up with your client's full amount of refined clean gold from the first part of that drop. the rest you can put back into your system.

3. Melting. You're using far far too much borax. Lightly coat a hot crucible and that's enough. You're meant to be dealing with high purity gold here.

I hope these comments help you refine (funny choice of words) what appears to be already a well thought out process.

Thanks again for the video.

Jon
 
3. Melting. You're using far far too much borax. Lightly coat a hot crucible and that's enough.
Jon, I think the reason he uses excess borax is to 'hold' the filter and powder from being blown out of the dish. Just my guess!
 
acpeacemaker said:
The button weighed 10.2g in the beginning but in the end showed 10.3g? :/ Maybe drag down or picked up from the dish?

There were some pieces of gold on the mold from the first pour. I scraped them off the mold and added them to the button. That is where the 0.1g came from.

kadriver
 
Many thanks to everyone who commented and critiqued the video. I always study these comments and find them very valuable.

kadriver
 
kadriver said:
Many thanks to everyone who commented and critiqued the video. I always study these comments and find them very valuable.

kadriver

I Just love your educational video's, and have learnt so so much from them, however I think my collection of Corning ware & your's would be equal. :)
I usually get them from Thrift/Charity shops for around A$1-$2.

Keep them coming & best regards from Down-Under.
Tony
 
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