Turning old jewelry into gold

/potassium metab.isulfate

Eileen Zhao

My uneducated guess about your gold's poor ductility is that it's caused by quenching the bars in water. Rapid differential cooling could introduce stresses in the material. In Cody's videos when he is flattening gold he deals with work-hardening by heating the gold to red hot and then letting it slowly cool to anneal it.

Brian Gordon

Yep SO2 gas is nasty 100 ppm potentially lethal dose LC50.

Daniel Blake Shoemaker

thanks for the offer, but i think its okay. And, okay cool, i will credit you properly!

Nile Red

Cody's more a backyard sientist while nile red is more a nurd rage.

Oxy_Cyan

really nice... I would love to send some jewelery to you for refining too, if i had any.... :D

Yep, electrolysis is how I ended up doing it. The 16-year-old me in the 1980s didn't have access to fancy chemicals. The silver thiosulfate is surprisingly resistant to reduction.

Silviu T

Silviu, normally silver from thiosulfate complex can be deposit via electrolysis. Or you can reduce the AgCl with NaBH4 or sugar and lye, there is so many ways.

I can send you the report from the spectrometer, the spectrum and a picture of the alloy (Lead + Cadmium + Bismuth + Tin) that says it has ~50% Iridium. And a spectrum from an alloy of platinum that really has iridium, if you think it fits your video. It would be nice to be credited as Victor Gonzalez.

Thanks!

Nile Red

Yeah mine was more of a one time thing, so i didnt worry too much about making it durable.

Nile Red

Very informative post. I really appreciate it. Im going to change the end of the video based on what you said. Would you want to be credited? If so, I can include your full name or just your first name. Whichever you prefer

Nile Red

Thank you Victor very nice comment. I remember in my youth I had to deal with silver recovery from thiosulfate solution (from processing photographic paper) and it wasn't straightforward. Dithionite was difficult for me to procure in those days when the internet was just a dream of the future, and precipitation with metals like copper and zinc was impractical due to silver depositing as a mirror on these from thiosulfate rather than as crystals.

Silviu T

Very nice to see videos about gold. I refine gold, platinum, palladium and rhodium for a living, and you made everything very close to what's normally commercially done. XRF doesn’t show the tungsten error because of density. W and Au have very close peaks and if you try to analyze 99.99% gold with an XRF gun that doesn’t have the “precious metals software” it will read Au as W. The same thing happens with lead and iridium, if you analyze Pb that has a bit of impurity in it will read as 50% Ir ~ 50% Pb. Your gold is at least 99.9% pure, how do I know? The dip that the gold made when it solidifies in the crucible (24:04 – 24:09), we call it “gold pipe” When pouring a bar, heat the mold to half the temperature of the molten metal, the bar will be smooth without these wave patterns. Also soot from a O2/LPG or acetylene/O2 torch in the graphite mold will help (yes soot on a graphite mold, strange isn’t?). You could just do Aqua Regia in those pieces, almost 90% dissolves, you save time, copper, acid, and waste treatment, then you can add sulfamic acid to neutralize the excess nitric dilute and filter. The gold residue with silver chloride can be mixed with a solution of sodium thiosulfate that will dissolve the AgCl, filter or decant and you can make aqua regia again to dissolve the last bit. Potassium metabisulfite is expensive why not sodium metabisulfite? You add to much of it as well, excess sulfite can contaminate the gold (mainly with silver). The best way is to make the precipitation with an ORP meter and stop at +450 mV. With time you get the “point” from the color. Bubbling SO2 gas is better yet to have a purer gold. If you would like to know something in particular, I'm here.

Very interesting! Yeah very possible that they misinterpreted the data.

Also if you look at the XRF spectra of Au and W they do have some peaks that are very close, maybe that's the source of the error: http://www.xrfresearch.com/xrf-spectrum-tungsten/ and http://www.xrfresearch.com/xrf-spectrum-gold/

Silviu T

Haha fair enough!

Plasma spectrophotometry has been around since the 19th century. Get off my lawn. :D (it's funny because I just had to chase some kids off my front lawn IRL)

Silviu T

haha newfangled, hasn't xrf been around for at least 50 years? (Not sure on that one) I wonder if you are referring to ICP-OES (around since the 90's?) or if that is an evolution of plasma spectrophotometry. I was thinking it was XRF because the spectra reminded me of a print-out i've seen before, but I can't for the life of me remember where! Either way, the density of W has nothing to do with either techniques. Thanks for the insight!

XRF is fancy and newfangled, but the classic way to quickly analyze a metal's composition is flame or plasma spectrophotometry. Basically you create a spark between the metal to be analyzed and another electrode, usually graphite. The light emitted by the spark is passed through a prism or diffraction grate, and the spectral lines photographed and analyzed. This is based on the property of metal ions in a plasma to emit characteristic spectral lines. The position of the lines in the spectrum tell you which metals are present, and the relative intensities of spectral lines for different metals give you the % of each metal in the alloy. However, based on some information in the graphs it does seem that Kitco used XRF instead.

Silviu T

What was used to determine Au purity? X-ray fluorescence? It would be great to know what instrumentation was used - it would let us dig deeper into the peak ascribed to W. The density of W has nothing to do with a possible "error in the machine". X-ray techniques are dependent on the electronic structure of the elements being analyzed. Please let us know if you can find this information out. It has certainly peaked my interest.

As others have pointed out here, this overlaps a lot with what Cody's done. However, the main thing I was thinking when watching his videos was "man, I'd love to see a NileRed take on this". And now I have, and it was as great as I expected! Thank you for your consistently-quality content. Looking forward to the silver recovery / waste processing video.

Michael Lang

Hmm, you should also consider cellphones they have A LOT OF GOLD plus nickel in the electrode structure. I used HCl plus H202 to break down the gold. Very cool Red Nile kind of reminds me of Cody.

Daniel Blake Shoemaker

Really enjoyed the video! As Silver_Scree said, interesting things like this never get old and the NileStyle makes it especially good!

Michael Aichlmayr

You might see if you can find an alternative interpretation for that spectrum peak they identified as tungsten.

Kevin Martin

No matter how many times I watch people do stuff like this, it never gets old. Having the NileRed-brand presentation style on it was a real treat, and I very much enjoyed this video. Marvelous work! Can't wait to see the video about processing the byproducts.

Not hugely novel (CodysLab did a lot with gold last year) but I like your clear and well structured videos

TOM

Was expecting this after the teaser. :) Now onto watching it. (edit) Finished watching, very detailed and thorough. Good job! I do want to see the second video though. I'm not surprised at the failure mode of the graphite crucible, those are really only suitable for electric furnaces. Your inquarting furnace is essentially a smaller version of mine, made from a bucket with kaowool insulation. The main difference is that I coated the inside of mine with several layers of a refractory clay called Satanite, this makes it a lot more durable.

Silviu T