# Refining CPU's with Aqua Regia



## Anonymous (Oct 19, 2007)

Hello everyone, 
This is my first post and I hope to learn a great deal everyone here. My cousin and I have completed the aqua regia process twice now. Both times, everything has gone according to plan. The solution has had the right colors at every stage (FROM WHAT I HAVE READ). Once we melt the gold it comes out looking like silver (inside and out). Any thoughts? Or even better, does anyone have a (tested and true)process that they would be willing to share me, step by step? Any help would be greatly appreciated.

Thanks,
Mike


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## goldsilverpro (Oct 19, 2007)

You obviously did something wrong. Can you provide a lot more detail on what you did? To start with, what type of gold scrap were you working with?


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## Anonymous (Oct 19, 2007)

We placed 5 Pentium Pro CPU's into AR until the reaction had stopped. We then filtered out all the CPU pieces. Set the AR (in glass container)on a warming plate and evaporated most of the acid out. Once we were close to the bottom we could see the reddish brown mud toward the bottom with a blueish-green substance on top. We added distilled water to it and evoporated it twice more (until most of the acid smell was gone along with almost all of the blueish-green substance on top). We then added 50% distilled water & 50% nitric acid to get rid of any other impurities (base metals). Evaporated it down then twice more with distilled water. We never evaporated all liquid completly out for fear of burning the gold to the bottom of the glass pot (during the whole process). Anyway, on the last go around we were left with a reddish brown mud toward the bottom with a murky tan liquid on top. We poured the murky tan liquid on top in a separate container and set it aside. Then poured the mud into a filter with a little rubbing alcohol and let in drain. Once drained it was set in the sun to dry. Once dry the filter with the dried mud was placed into a crucible. Borax was sprinkled onto the filter durning firing. Upon completion the metal ball came out looking silver in color. We clapped down on it with a pair of pliers to give it flat surface, so it wouldn't roll away and it broke. After looking at it through a jewlers loupe we could see that the inside looked silver also.


Please let me know if there is any other information you need to make an educated guess on what happened. 

Thank you for your time and patience,
Mike


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## Harold_V (Oct 19, 2007)

Mike,

Please accept this post in the spirit in which it's being presented. Your procedure is totally wrong, and should be abandoned. 

Let me enlighten you. I'll comment on your statements, and try to make corrections as we go.



> We placed 5 Pentium Pro CPU's into AR until the reaction had stopped. We then filtered out all the CPU pieces. Set the AR (in glass container)on a warming plate and evaporated most of the acid out



Is it safe to assume that when you removed the pieces, that anything metallic was totally dissolved? If not, any remnants of base metals would have precipitated traces of gold, so you'd possibly lose that amount when you transferred the solution. 

I do not recommend using AR to eliminate base metals, although there are cases when that is your only option. Removing gold from ceramics is one of them. 



> Once we were close to the bottom we could see the reddish brown mud toward the bottom with a blueish-green substance on top. We added distilled water to it and evoporated it twice more (until most of the acid smell was gone along with almost all of the blueish-green substance on top).




For starters, there is no need for distilled water, not in this process. Adding water defeated the purpose unless evaporation was complete. 



> We then added 50% distilled water & 50% nitric acid to get rid of any other impurities (base metals).



Adding nitric acid was a mistake. That's what you're trying to eliminate---there is no other purpose in evaporation. The acid that should have been added would be a couple drops of sulfuric, which expels lead as lead sulfate and can be filtered out, and HCL---which accelerates the evaporation of nitric. Evaporation should be carried out until nitric is completely absent, at which time the now very dark solution should be diluted with water (tap water is more than acceptable), and then filtered to remove particulate matter. 



> Evaporated it down then twice more with distilled water. We never evaporated all liquid completly out for fear of burning the gold to the bottom of the glass pot (during the whole process). Anyway, on the last go around we were left with a reddish brown mud toward the bottom with a murky tan liquid on top. We poured the murky tan liquid on top in a separate container and set it aside. Then poured the mud into a filter with a little rubbing alcohol and let in drain. Once drained it was set in the sun to dry. Once dry the filter with the dried mud was placed into a crucible. Borax was sprinkled onto the filter durning firing. Upon completion the metal ball came out looking silver in color. We clapped down on it with a pair of pliers to give it flat surface, so it wouldn't roll away and it broke. After looking at it through a jewlers loupe we could see that the inside looked silver also.



Wrong! Wrong! Wrong!

You do not dry the material, you filter it and selectively precipitate the values using the proper precipitant. What you did was nothing more than dissolve everything that would, screw around with it for a long time, then reduce it to the basic elements once again. You now have a button of junk that contains values, and will require repeating the entire process properly in order to recover the values. 

Evaporation does NOT have the ability to remove contaminants. 

I'm going to recommend you stop doing everything you've been doing and don't start again until you've obtained a copy of Hoke's book, Refining Precious Metals Wastes. You clearly do not understand the process of refining. That book will teach you what to do, and how to do it. While it does not specifically address refining electronic scrap, the principles of refining don't change, only the recovery processes do. You'll learn all about that here on this forum, using techniques that are within your capabilities, especially if you have difficulty buying proper acids. 

We're here to help you, Mike. Don't get discouraged, and please do not take offense to my post. 

Harold


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## Redders (Oct 19, 2007)

Mike, I did similar things and Harold helped me to recover (i'm new, too). I reckon that our fundamental mistake is that you have to get all the base metals out before you use AR on the gold. Steve's mantra, 'Garbage in = Garbage out'.... In this case the garbage is the legs and the metal lid under the gold plating.

I hope that someone with experience in processing processors jumps in here because I need a strategy also. Maybe you get some processors and crush them, incinerate them, hit them with nitric to remove base metals, wash, incinerate again, wash and then AR....... anybody happy with their strategy on ceramic processors? (then tell me about green fibre P3 processors)

Mike, I had a similar mess to yours and you may want to research around this site for the 'crock pot' solution. I found some values in the liquid that you have 'set aside' You put some steel in the pot and powdered metals come out of the liquid. Then you have to deal with the iron, copper, nickel, zinc, tin, whatever, that may be in with the gold. At the end of all this there will be very little return. I gave up on the tan mud. Mike you understand that I am at the the same level as yourself... you gotta listen to the 'main men' on this.

I will watch this thread...... good luck.


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## Anonymous (Oct 19, 2007)

I take no offence to any replies to my post. I would like thank every and anyone who replies. I joined this forum to learn from people who are better educated and more experience than I am. Please don't worry about being harsh. We will do some more research and try again (hopefully with more knowledge).

Thanks again, 
Mike


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## Harold_V (Oct 19, 2007)

Redders said:


> Mike, I did similar things and Harold helped me to recover (i'm new, too). I reckon that our fundamental mistake is that you have to get all the base metals out before you use AR on the gold. Steve's mantra, 'Garbage in = Garbage out'.... In this case the garbage is the legs and the metal lid under the gold plating.



His fundamental mistake was not precipitating the values from the solution, but, instead, reducing the contents with heat, back to metals. Somewhere along the way one must separate the values from the base metals, That never happened in this case, they were simply dissolved, then combined. The volume of base metals as compared to the slight trace of values would overwhelm the gold color, yielding anything but a yellow alloy, assuming there was little copper involved. 

As much as it pains me to say it, extracting gold with AR when there are base metals involved is a tolerable situation (although very best avoided if possible), assuming you expect to re-refine the gold that comes from such a process. It's sure to be contaminated, enough that you could struggle trying to achieve a level of purity that is in keeping with industry standards, even with careful washing. Doing so by fluxing and melting borders on the impossible. 

This all depends on the objective of the individual. There's room for those that extract gold and don't particularly care about quality----as long as they're selling it to others that will refine it to bring it fine. If money is the objective and you're willing to settle for less than spot, there's nothing wrong with that approach. Some enjoy the recovery-----while others, myself particularly, enjoys refining. They're not the same thing. 

Harold


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## Never_Evil (Oct 19, 2007)

Steve has posted a similar experiment where he used the Muratic acid and Hydrogen peroxide solution to disolve the legs of cpu's. It takes time to do it this way, so do not rush it. I too have done the AP method on ceramic processors and it does work. As recommended HOKE'S book is invaluable. Buy it and read it. Good luck with your next batch.


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