Cementing gold

[sayf]

I have big amount of gold plated pins, some of them is magnetic , i already got rid of tin and lead so they are ready for diluted nitric
but am wondering if i can directly use aqua regia then precipitate gold and refine it in another step

i know that the iron or the copper in the pins may cause the gold to cement from aqua regia during the reaction and this will cause problems
but am wondering if my aqua regia is concentrated enough, will the cementing by copper or iron be possible?
assuming that iron started cementing copper and gold, will the aqua regia be able to redissolve them?
regards

 

[Geo]

As long as ALL of the metal dissolves, the gold will remain in solution until you precipitate it. If any of the base metal remains in metallic form, it will cement the gold from solution. If you try to go with straight AR, continue with the dissolution until there is no solid metal left.

 

[sayf]

As long as ALL of the metal dissolves, the gold will remain in solution until you precipitate it. If any of the base metal remains in metallic form, it will cement the gold from solution. If you try to go with straight AR, continue with the dissolution until there is no solid metal left.

Thanks for your reply Geo but how can you explain this
i put about 1 kg of ceramic cpu directly in AR
after the reaction has stopped and all metals dissolved in aqua regia, i came back after a smoke to find that a 23k gold has precipitated.

 

[Martijn]

Sayf, how do you know it's 23k? Do you know what the 4% other metals are in there?
And did you wash the powder according harold's procedure: 'getting pure shiny gold'?
SMB can precipitate other metals from a 'dirty' solution.

Martijn.

 

[FrugalRefiner]

after the reaction has stopped and all metals dissolved in aqua regia, i came back after a smoke to find that a 23k gold has precipitated.

How do you know all metals dissolved? It can take quite some time to dissolve all the metals in ceramic CPUs.

Dave

 

[Geo]

Thanks for your reply Geo but how can you explain this
i put about 1 kg of ceramic cpu directly in AR
after the reaction has stopped and all metals dissolved in aqua regia, i came back after a smoke to find that a 23k gold has precipitated.

I can't. No one can. You are assuming. A small amount of iron can cement a lot of gold from solution. You did not dissolve all of the metal originally. If metal cemented out, any metal, you did not dissolve all the metal on the processors. Just because the reaction stopped does not mean that all metal was dissolved. A reaction can stop for multiple reasons. It could have been depleted of one of the reagents. The solution could have simply became saturated with metal salt. What ever the reason was, there was still metal present. The ceramic bodies should be smooth where the legs was attached and the small areas where the legs was attached should be a light green color. If the bodies are not smooth or the areas where the legs were are black or rough, there is still metal present and the dissolution needs to continue.

 

[sayf]

Sayf, how do you know it's 23k? Do you know what the 4% other metals are in there?
And did you wash the powder according harold's procedure: 'getting pure shiny gold'?
SMB can precipitate other metals from a 'dirty' solution.

Martijn.

Hey martijin i filtered and melted the gold and it was 23+ k
i think its luck maybe
chemistry is making me mad

 

[Martijn]

We love button pictures! Show it off!

 

[sayf]

Haha ok sir, not a perfect melt though

 

[Martijn]

You need more heat. Get it into a flowing ball.
Edit: but nice gold color. Pretty pure i think. And a good size :G
But impossible to get an accurate purity measured from. It's not homogeneous enoug by far.