Aluminium removal from Gold

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Byron Bound

New member
Joined
Jun 5, 2019
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1
Howdy!
I have not been able to find the right posts with info regarding this, any links would be greatly appreciated.

I am a Jeweller in Aus and tried sand casting with some fancy new aluminium rings. Cleverly using 18ct yellow gold I accidentally poured some gold onto the aluminium. I did not realise it would happen, however the gold alloyed to the aluminium.

I dropped the blend into some Hydrochloric acid, I had a very small amount handy, assuming it would convert the aluminium into aluminium chloride and leave the gold and copper content.

Now, did I do the right thing? Or should I have approached this differently?
Before proceeding further, what is the best mothod to then remove, wash and remelt the gold.

As a second I have some alloyed gold/copper/silver that I would like to separate also, can you point me to the best posts regarding this process as my only experience is watching Cod's Lab the past few years and do not want to approach this unsafely. Doing my own refining will work very well as I have about 20gm of gold to refune currently that I would love to recast into new jewellery.

I have all the materials and setup there, just lack quality instruction or direction pointing to safely proceed.

Cheers
Zac 😊
 
For separating the Gold, Copper and Silver, you can search for a process called inquartation, followed by Nitric acid digestion of the Silver and Copper.

I don't have any experience with Gold/Aluminium alloys, but in theory I would think a process similar to inquartation with digestion with HCl should work.

To deal with decent quantities of Gold, you would really have to invest in a fume hood, decent glassware and a fair amount of education, if there are refiners in your area, you might find that it works out relatively cheaply to just get your metals separated and refined by someone who is already set-up.
 
Couldn't NaOH also dissolve aluminium?

by the way, did you manage to make anything purple :)

https://en.wikipedia.org/wiki/Gold%E2%80%93aluminium_intermetallic

?
 
I've seen hcl and dilute caustic both used. Both forming the nice gel substance a lot of us know causing passivation. Heat and agitation both were used in each setup, but it always has its dangers for the wrong person.
 
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