Stripping some base metal with aquaregia

[bhilton]

Hi All,

I'm curious, if I poured 10 grams of 10-14k karat gold into shot and placed it in HCL on heat, as I slowly add nitric acid 1ml at a time, forming aquaregia, will it only dissolve base metals first?

I am not suggesting this is a good practice, but I was wondering, based on the reactivity series, each 1ml shot of nitric acid would dissolve copper and silver and nickel first, leaving gold alone, right? Or if it dissolves some of the gold, if I give it some time on heat, the base metals would displace the dissolved gold, I think?

I could then pour off the solution (saving for another round later) and if done with supervision and stannous testing, I could in theory remove most base metals and then rinse the remaining gold material and go to aquaregia again, which would be fairly clean and free from most base metals.

Anyone ever try this?

 

[Yggdrasil]

Hi All,

I'm curious, if I poured 10 grams of 10-14k karat gold into shot and placed it in HCL on heat, as I slowly add nitric acid 1ml at a time, forming aquaregia, will it only dissolve base metals first?

I am not suggesting this is a good practice, but I was wondering, based on the reactivity series, each 1ml shot of nitric acid would dissolve copper and silver and nickel first, leaving gold alone, right? Or if it dissolves some of the gold, if I give it some time on heat, the base metals would displace the dissolved gold, I think?

I could then pour off the solution (saving for another round later) and if done with supervision and stannous testing, I could in theory remove most base metals and then rinse the remaining gold material and go to aquaregia again, which would be fairly clean and free from most base metals.

Anyone ever try this?

It will dissolve some Gold some base metal and stop due to the formation of Silver Chloride.

 

[Shark]

It comes down to time versus cost. Most secondary methods often cost more in time and sometimes quality as well. For one or two pieces, just go with AR and beat the silver chloride crust off, or inquarter if your doing more than a few pieces.

 

[bhilton]

It will dissolve some Gold some base metal and stop due to the formation of Silver Chloride.

I tried tonight for a fun experiment and it went exactly like you said.