i disolved my gold ????

[donald236]

OK here's the deal i ran a batch of 600grams of fingers in a AP bath . they came off real nice and quite fast so i decided to run another batch in the same bath . same amount . i was expecting around 6 to 7 grams of foils . these were high grade fingers . however when i did my filtering i wound up with 1.4 grams of foils . my question is i believe that the gold is there in the solution it just simply dissolved in the bath . can someone please remind me on how to get it out of a ap bath :?: what do i do just smb it :?: or what do i do :?: any details will be helpful
thanks in advance

 

[lazersteve]

Don,

First test with stannous chloride to confirm the gold is indeed in solution.

You can get the gold out with SMB, but you will have to filter the solution withing 24 hours or the gold may redissolve if your peroxide content is high.

You can also just keep saturating the solution with copper and the gold will eventually all precipitate. You'll have to refine this gold again for purity.

If all else fails you can push the gold and copper out with iron and dissolve the copper that forms with HCl to return the gold as a dirty black powder. This method eats up a lot of HCl, but it is pretty much guaranteed you won't leave any gold in the AP.

The amount of gold that you stated that was absorbed seems very high, did you use a lot of peroxide or heat the bath?

Lastly, you should always remove the foils from one batch before reusing the AP.

Steve

 

[Oz]

Steve,

I have had the same thing with foils. Now you see them, now you don’t. I knew about the copper for pushing it out of solution but not the steel, should have known thinking of other reactions.

I have some AP that also has some iron in it, will stannous still give me a reliable indication of gold presence in solution. I had heard iron could interfere with stannous.

Lastly I have some AP with gold in solution that SMB failed to precipitate will copper or steel still precipitate the gold with SMB present? If so are there any special considerations in re-refining this precipitate since it has already been exposed to SMB?

 

[lazersteve]

Oz,

When you are having trouble getting the gold out of AP iron or steel will push the copper and gold out. HCl will rapidly dissolve the finely divided copper and the gold powder will remain.

As far as the stannous iron thing, I've heard that also, but I have no documented confirmation.

Zinc may even be a better method than steel, but more expensive. The resulting black powder should be treated HCl first then with 50/50 nitric to assure removal of all precipitated base metals (and Pd if present). What remains can be washed and treated with fresh AR or HCl-Cl to put the gold into solution. EDIT: The HCl removes the bulk of the soluble base metals to conserve on nitric.

Steve

 

[Platdigger]

Just to beat Harold to the punch....

Make sure you incinerate between hcl and nitric washes....
Randy

 

[Oz]

Point taken Platdigger, thanks for the reminder.

Thanks Steve, I'll give it a try when I get back to the homestead.