Help with AP & Melt gold foils

[lawsonland]

Hi Again,
I wanted to see why after using AP to get rid of the base metals you dissolve the foils and precip out? If you know the purity of the gold is 99.99% can you just melt them after the AP?

I have Military grade plated gold over base of nickle and then copper.
I know for fact that the purity is 99.99%
I put a sample into AP.
Right now AP is emerald green with the foils on the bottom and a little black (dust/material) also on the bottom.
The copper has been disolved
The gold foils are coated on one side the a black film (bright gold on the other). If I wipe off it looks like the nickel is there.
1) what is the black film?
2) how long does nickel take to disolve? Longer than copper?

Will the foils get contaminated and if I melted them after the base metals are gone would the purity would be less than 99.99%?
Thanks for you help and advice.

 

[lazersteve]

Hello,

The black is likely gold that has dissolved in the AP then cemented out as the base metals dissolved and precipitated the gold as a fine black powder.

Nickel will dissolve before copper in most situations.

The nickel layer you are referring to may not be nickel, just nickel colored. The nickel will usually form a fine grayish white powder in AP, that dissolves in the HCl.

Gold that is applied to items at 99.99% is no longer 99.99% when it is recovered due to contamination from many other sources. Melting straight out of AP will only contaminate it with more garbage. The added steps of cleaning, dissolving, and preciiptating the fine gold from the foils is a must for high purity.

Steve

 

[ljmolina]

Steve, what do we do with the black-gold, do I proceed using the Muratic+Clorox mix to get rid of the impurities and then SMB?

Or is there a seperate process with the fine black powder??

thanks

 

[leavemealone]

Steve, what do we do with the black-gold,

Pour it into a barrel and sell it to exxon.

do I proceed using the Muratic+Clorox mix to get rid of the impurities and then SMB?

Or is there a seperate process with the fine black powder??

You should not have black powder until after the "muratic+clorox" and smb step.Up to that point should only have foils with no powder or extremely little powder.If you have an excess of powder then you used too much peroxide in your AP step.That is a problem that plagued me when I started processing.I did not have the patience required to allow the AP to digest the metals at its normal rate,so I added more peroxide and stronger peroxide to dissolve the material faster.The only problem is that the gold will also dissolve into solution.Too high of a concentration and you will be pulling your hair out to try to precipitate also.
After you have the foils and powder,you will still need to dissolve and precipitate as a purifying step,and you will still need to wash the powder after you have precipitated with smb.3 water,3 acid,3 water,use about triple the volume of liquid for the volume of powder,and decant after each step.........your patience will be rewarded.
Johnny