Disolving Gold

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PeetPb

Member
Joined
Feb 23, 2012
Messages
7
Hi, I've recently tried to dissolve gold in poor man's aqua regia from old PC scrap. When I came to the part where I should precipitate the gold from the chloroauric acid, all I've got was a little bit of a gray powder(probably Silver/Platinum ?) but all the gold plating from the pins was gone. Where did I make a mistake ? I used NH4NO3 to make poor man's AR. Maybe I used excess of the nitrate. The other thing may be that I overheated the stuff. Any advice how to improve this ?
 
Have you read HOKE? Did you dissolve base metals first? How much, and what type of material did you have in this batch? Did you evaporate off the nitric? How much of the sodium nitrate did you use? What type of precipitant did you use? If you're asking for advice, I would suggest putting a halt to your experiment. Read HOKE and do some searches on this site. I'm sure you can find something along the lines similar to what you're going through right now. Without more detail, I really don't even know where to start addressing the problem. Read first. Understand what you're doing. This stuff is too dangerous to just "wing it". Don't mean to come across as rude. You asked for advice... this is what I would suggest.
 
We need to know more to help! What materials are you working with(pins,boards,chips???) Did you eliminate base metals before going to AR? Do you know the hazards and safety when working with these chemicals?

Acid_Bath, you beat me to the punch!!! :lol:
 
if you had base metal left, any gold will be in a light black powder with the material you decanted the solution from. thats why you remove base metal first. gold will cement out of solution onto copper quickly and zinc or aluminum even faster. you should study some more before try another process.
 
thanks for the replies, I'm aware of the dangers I actually know something about chemistry however I've never tried this kind of experiments. I've read something and I was following a guide (this one
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=48&t=3548&p=30062#p30062
that I found on this forum. And the problem really might be the base metals. I have washed the pins with hot HCl but it seems that I should have done it more than once :D ... anyway thanks for the advices
 
PeetPb said:
thanks for the replies, I'm aware of the dangers I actually know something about chemistry however I've never tried this kind of experiments. I've read something and I was following a guide (this one
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=48&t=3548&p=30062#p30062
that I found on this forum. And the problem really might be the base metals. I have washed the pins with hot HCl but it seems that I should have done it more than once :D ... anyway thanks for the advices
Click to expand...

ok. now comes the question.what pins are you working with? are they header pins or from processors? there's a big difference, header pins and some slot connector pins are copper base metal and cpu connector pins are steel/kovar base metal. either way, just washing them will not remove the base metal from the gold. there are two different processes that need to occur.

reclaim the gold: separate the gold from base metal. methods include AP, stripping cell, even a prolonged boil in hcl to name a few.

refine the gold: remove impurities from the gold. methods include AR dissolution, hcl/cl dissolution, cyanide dissolution just to name a few. and then precipitate a more pure metal leaving impurities in solution.
 
I was working with header pins ... I've got processor pins too but I saved them for later because I wanted to learn some skills first ...I will certainly check those methods out before trying this again
 
Peet---

If as you say, all the gold plating was gone from the pins, then the pins are still solid because you didn't dissolve them completely. Those pins will now cement gold onto themselves. Find particles of gold will appear gray or black. Don't throw those pins away!

If there was some gold in solution, it would probably precipitate as a fine gray powder, from a solution with base metals also dissolved in it. So it's likely that your powder is some of your gold.

If you use the "dissolve everything" method, as you have done, then you should actually go ahead and dissolve everything, to avoid ending up with your gold spread between cement on the pins, still in solution, or sometimes in dark powder on the bottom of the vessel even without adding a percipitant (as the base metals will percipitate some of your gold as a cementation drop).

Generally the "dissolve everything" method is highly non-optimum. The methods listed by Geo are the most common and easiest. You can use the search feature to see lots of posts about them. You will realize after reading the book recommended by Acid_Bath, there are links to free downloads of it on this forum (again, just use the search for it).

Don't get frustrated. 8)
 
PeetPb said:
thanks for the replies, I'm aware of the dangers I actually know something about chemistry however I've never tried this kind of experiments. I've read something and I was following a guide (this one http://goldrefiningforum.com/phpBB3/viewtopic.php?f=48&t=3548&p=30062#p30062) that I found on this forum. And the problem really might be the base metals. I have washed the pins with hot HCl but it seems that I should have done it more than once :D ... anyway thanks for the advices
Click to expand...
Do not gloss over the suggestion that you should read Hoke's book. I did not read an acknowledgment that you have. That you know something about chemistry makes no difference. If you don't know how to refine precious metals, you don't know what you need to know.

Have your read the book?

If not, why not?

Until you do, and you understand what she teaches you, please don't ask questions on the forum. They have all been answered numerous times---and are almost always a sign that the individual in question refuses to do their homework. We're not very good at spoon feeding folks here. We insist that you do your share before we try to help.

Harold
 
PeetPb,

Can I add this?
You should try and get sodium nitrate or potassium nitrate.

The ammonium nitrates these metal powders and heat can be very dangerous combinations if not handled properly, study up some on the chemistry here.

Hoke's book does not teach chemistry, but she teaches you how to recover and refine the metals, how to deal with may situations you will run into, how metals react to various acids, how to test solutions, it is a must read for an understanding, she will not teach how to recover or refine values from electronics or from ore, but the principles she teaches are invaluable when working with these also.
 

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