Precipitation Of Gold from spent Acid gold plating Solution

[papap]

I am interested in recovering about 3 troy ozs of gold from an acid gold plating solution pH 4.3,which does not work because of neglect(no maintenance) for many years.I could try to electrowin it,but I would like to precipitate it with SodiumBorohydide because it is a much faster process.What I am not sure isoes it precipitate all the Gold? And is the precipitate,easily melted with a propane torch?
I could experiment with it,but I hope there are experts on this board, that can save me of trying to reinvent the wheel.Also I can not find references on using NaBH4 to precipitate Gold on this board.I know NaBH4 is a powerful
reducing agent,but I have not in all my searches find many recommendations for it,and it makes me wonder if it is the way to go.

Thank you
papap

 

[Lou]

Will work just fine. Stir with air powered mixer and add slowly--avoid spark or flame!

 

[4metals]

The reason we don't discuss the Borohydride on this forum much is because the Borohydride is such a powerful reducing agent that it would bring down all of the other metals in a solution as well. In your case it isn't likely an issue as it was a gold plating solution, but for most solutions we generate here the precipitant needs to be a bit more selective to attain the purity we seek.

Plus sodium borohydride (or Venmet solution) is something that isn't available readily to most of our members so it never comes up.

 

[FrugalRefiner]

For the record, a search for borohydride turns up 124 results.

Dave

 

[Lino1406]

Regarding Venmet solution - I assume a trial with only NaOH is preferred considering the wild reaction of borohydride

 

[Lou]

4metals, in situations where there are a bunch of other metals (like copper and nickel), sometimes it is expedient to halfway reduce the lot and let the other metals cement out the precious metals.

There are some instances where borohydride is rather tame!

 

[goldsilverpro]

There should also be some cobalt or nickel in the hard acid gold solution.

 

[Barstool miner]

hi Papa, Sodium Borohydride is a catch all precipitant not advisable . If you have gold chloride solution use
a chlorine neutralizer such as sodium thiosulfate ( used to clean tap water of chlorine suitable
for Pet fish tanks )

Barstool Miner

 

[Lou]

If it's acid gold sulfite, just add sulfuric acid to pH 1. nothing better.