SteveD
Member
Hi all,
I hope you can help me unpickle my mess!
Refining karat gold using nitric and aqua regia.
I came to this a noob, not having done any chemistry since A level many moons ago.
Wanting to refine some gold with the view of making 18k Palladium white gold I started with about 40g of 9k and about 10g of 18k, I calculated approx. 20g Au and decided to inquart with copper, so melted it with about 10g of copper wire thinking the remaining base metals in the alloy would make up the difference for inquartation, basic maths error! 60g of material of which 20g is Au gives a third which seems isn’t enough to get all the base metal out in a nitric boil, see below.
I boiled with Nitric and removed a quantity of blue liquid which I assume is copper nitrate.
I couldn’t get it to fully clear the blue colour and was starting to run out of nitric, so after most (not all) of the blue colour stopped coming from the boil I washed with distilled water, boiled with conc HCL then added nitric to start dissolving the gold.
I can only assume the amount of base metal was too low and the gold was ‘hiding’ more copper because on adding the nitric I got a lot of brown gas, and the solution turned more and more blue/green. Panicking a little I decanted all of the liquid into a fresh beaker (beaker 2) leaving some brown metal sponge behind in beaker 1. I then added waaay to much Sodium Meta bisulphate to the decanted liquid in beaker 2.
I added more HCL and nitric to the metal sponge in beaker 1 and heated it which started producing brown gas and turned blue then green.
So I stopped and put them to one side and did a bit more reading. I got a Stannous test kit – the liquid with the SMB excess in beaker 2 tests negative and the dissolved sponge liquid in beaker 1 positive.
The questions is what to do with each beaker?
Beaker 2 has a lot of SMB in it – which I’ve read can be dissolved out with water leaving any metal powder behind which can then be incinerated and meted into a button. The liquid above the layer of SMB tests negative with Stannous but the colour to me suggests something other than copper in it – can I be confident this isn’t Au?
There is also a slick of what I thing is gold particles on top of the liquid which I remember being something to do with grease? How do you sort this out – lift it off with filter paper and incinerate the paper? Use a solvent to drop it down?
With the dissolved sponge in beaker 1 I’m planning on adding SMB to drop any Au, filter then to incinerate and melt back to a button and start again (this time with silver to inquart.) Is this a sensible approach?
Thanks in advance – it’s harder than it looks isn’t it!
I hope you can help me unpickle my mess!
Refining karat gold using nitric and aqua regia.
I came to this a noob, not having done any chemistry since A level many moons ago.
Wanting to refine some gold with the view of making 18k Palladium white gold I started with about 40g of 9k and about 10g of 18k, I calculated approx. 20g Au and decided to inquart with copper, so melted it with about 10g of copper wire thinking the remaining base metals in the alloy would make up the difference for inquartation, basic maths error! 60g of material of which 20g is Au gives a third which seems isn’t enough to get all the base metal out in a nitric boil, see below.
I boiled with Nitric and removed a quantity of blue liquid which I assume is copper nitrate.
I couldn’t get it to fully clear the blue colour and was starting to run out of nitric, so after most (not all) of the blue colour stopped coming from the boil I washed with distilled water, boiled with conc HCL then added nitric to start dissolving the gold.
I can only assume the amount of base metal was too low and the gold was ‘hiding’ more copper because on adding the nitric I got a lot of brown gas, and the solution turned more and more blue/green. Panicking a little I decanted all of the liquid into a fresh beaker (beaker 2) leaving some brown metal sponge behind in beaker 1. I then added waaay to much Sodium Meta bisulphate to the decanted liquid in beaker 2.
I added more HCL and nitric to the metal sponge in beaker 1 and heated it which started producing brown gas and turned blue then green.
So I stopped and put them to one side and did a bit more reading. I got a Stannous test kit – the liquid with the SMB excess in beaker 2 tests negative and the dissolved sponge liquid in beaker 1 positive.
The questions is what to do with each beaker?
Beaker 2 has a lot of SMB in it – which I’ve read can be dissolved out with water leaving any metal powder behind which can then be incinerated and meted into a button. The liquid above the layer of SMB tests negative with Stannous but the colour to me suggests something other than copper in it – can I be confident this isn’t Au?
There is also a slick of what I thing is gold particles on top of the liquid which I remember being something to do with grease? How do you sort this out – lift it off with filter paper and incinerate the paper? Use a solvent to drop it down?
With the dissolved sponge in beaker 1 I’m planning on adding SMB to drop any Au, filter then to incinerate and melt back to a button and start again (this time with silver to inquart.) Is this a sensible approach?
Thanks in advance – it’s harder than it looks isn’t it!