# help



## geonorts (Sep 13, 2009)

please read
I have done my first small test batch of ceramic cpus, soaked them in nitric acid for a week, then in hcl for a week,tested the nitric for silver and there was a fair bit, used aqua regia to dissolve gold, then filtered using coffee filters tested for silver before hand and there was next to nohing. 

Okay here is where I need advice i used formic acid to destroy the nitric once this was done I noticed an orangey brown precipitant at the bottom so I decanted off the liquid and captured the precipitant then proceeded to drop the gold from my liqiud using SMB but all I got was a whitish substance settling out. 

my questions are;
was the orangey bown precipitant my gold or is it still locked up somewhere?
has anyone used formic acid?
what is the whiteish precipitant?

can anyone help me, I can post pictures tonight if needed


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## geonorts (Sep 13, 2009)

here is the pictures

the first one is the orangy brown precip (gold?), i tested it with a magnet and nothing happened so i know there is little to no iron.






this one is the whitish precip (not silver chloride) precipitated when SMB was added after formic acid to AR


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## glorycloud (Sep 13, 2009)

Well the first picture sure looks like all the gold that I have
precipitated and refined. You will have to wait on one of the 
pro's for the second picture and what the white precipitant
might be.

Nice color on the gold powder though!! 8)


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## eeTHr (Sep 14, 2009)

geonorts;

You can read-up on the uses of formic acid in refining here---
http://goldrefiningforum.com/phpBB3...t&sd=d&sr=posts&st=0&ch=300&t=0&submit=Search

Pertaining to gold, it appears that its only use is to precipitate it. Edit added: But I have never seen it directly recommended for that by anyone on this forum, and I assume that there is a reason why they don't. I try to stick to what they recommend for beginners, because it is both easier _and_ safer.

I'm no expert, but from what I've read on this forum, the white stuff could be due to excess SMB.


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## stihl88 (Sep 14, 2009)

Geo, if you want to make some quick and nasty Stannic Chloride but quite usable then go to an op-shop and grab yourself one of those old "Pewter" (Tin) cups for a couple of dollars. Break off a small chunk the size of a 10c piece and use a clean file and file off about half and dissolve the filings in some warm/hot HCL (about 20ml) and test your solution for gold with it.


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## geonorts (Sep 14, 2009)

i work at a computer recycling place, does anyone know if any parts of a computer are clean tin and zinc


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## Harold_V (Sep 15, 2009)

Tin is unlikely in a computer except in alloy such as bronze or in solder. I am speaking of tin, the element, not thin steel commonly called "tin". 

You may find some drive housing made from a zinc alloy, but pure zinc is unlikely. Such housings can be tested with a drop of nitric. Aluminum does not react to nitric, and zinc does, with a vengeance. HCl dissolves both of them. Zinc is a common constituent in brass. 

Harold


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## Platdigger (Sep 15, 2009)

Geonorts, I am interested in your formic acid results.

I am curious if perhaps there was just very little nitric
left in solution when you added the formic.....

How much formic did you use?
Randy


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## geonorts (Sep 15, 2009)

I did 25 ceramic cpus after removing most base metals with nitric then hcl, the pins where dissolved with AR made of about 60-80ml nitric around 80% conc and 120-140ml hcl of around the same conc plus some water added when rinsing to get the gold from one container to the next and rinsing filters, this dissolved all the gold and once filtered I used around 90ml of 80% formic acid in all but around 20 ml at first and heated the AR in a boiling water bath once reaction started cold water was used to control the heat produced but i kept it quite hot then added 30 ml more formic once reaction slowed then another 30, once reaction wouldn't continue I added a bit more just to make sure all nitric had reacted once it cooled I noticed the precipitant at the bottom. 

I have decided for my large batch I am going to try this again with half and the urea SMB method on the other and see if there is any difference in look and yield.


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## Platdigger (Sep 15, 2009)

If I may, how much do you pay for formic?


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## geonorts (Sep 15, 2009)

85 % conc i think was around the same as my nitric which was $2.80 a litre I can find out the exact price if you want


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## Platdigger (Sep 15, 2009)

That's fine Geonorts, the price could be way different here in the States.
Sounds like a bargin for you though.

4metals posted a method of getting very pure silver from silver nitrate with sodium fomate and fomic acid.
Now you have me curious if there may be a viable method for using these for gold in AR.


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## stihl88 (Sep 16, 2009)

geonorts said:


> 85 % conc i think was around the same as my nitric which was $2.80 a litre I can find out the exact price if you want



Geonorts, do you mind telling me where you got your Nitric Acid from? I'm getting sick of making my own...

Cheers


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## geonorts (Sep 16, 2009)

i get it from a chemical supply place in Adelaide called polytreat if your still interested i can pm you his phone number


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## donnybrook (Oct 6, 2009)

Formic Acid.

As well as expelling nitric it is used to drop all metals from a boiling solution in the same way soda ash is used. Computers having both tin and copper and some form of magnetic iron in the CPU's can cause the Valences to dance around like Michael Jackson. I have a friend working on computer components and they have had more luck after removing the tin first. Some of the gold plating is coated with a varnish or lacquer and it can prevent the initial kick off in reaction. Apply heat and once it starts to work just let it go.

My own experience with computers involved using AR. I then added aluminium foil to the solution after removing the nitric by boiling (a tried and proven method). I added SMB and only a small amount of au dropped, and then the aluminium foil. You will see your gold come to the top as a brown powder and sometimes as gold flakes as the excvhanges occur. When you start to see green powder it is usually copper and at that point I stop (some recommend it). Let it settle and filter out the precipitate for further dissolution (after drying) in AR and recovery of gold using SMB as a seperate step I then continue with the aluminium foil to recover all metals associated with it in the periodic table. Especially if looking for the Platinium Palladium Metals which might not be there in computers. 

You can go all the way instead of stopping when the green powder rises and continue to bring copper down and then smelt or melt (your choice of words as melting is reducing to a pure metal) I have it on video.

donnybrook


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## Harold_V (Oct 7, 2009)

donnybrook said:


> (your choice of words as melting is reducing to a pure metal) I have it on video.


Your video is wrong. 
Otherwise, I would be lead to believe that one smelts all alloys, and melts pure elements. That is simply not true. One does NOT smelt 14K gold, one "melts" 14k gold. 

Smelting is the act of reducing metals from ores. Melting is the act of heating recovered elements from the solidus state to the liquidus state. They can be mixed, or stand alone-----they need not be pure, although that does affect the melting point. In all cases, they are melted, they are not smelted. 

Harold


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## donnybrook (Oct 7, 2009)

Thanks Harold,
As I said "your choice of words". I simply flux it after preparation,add it to the crucible,apply heat,when the charge is calm pour it,or if using a clay crucible a good two pound hammer applied to bottom when cold works well. Retain my slags because if copper is involved there is a chemical process occuring in the crucible, like Monks in a Monastery someone is always behind someone else. I think it was called something like "the order of oxidisation". It could be referred to in Hoak or within work by Bugbee. 

Granulate and undertake a dissolution using just nitric if you prefer. Get your powder,filter and then undertake another dissolution,get your acid right (boiling the preferred method),and drop in whatever way you like with whatever you like Copperas etc.

Again thanks,
donnybrook


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## eeTHr (Oct 7, 2009)

donnybrook;

What Harold is saying it that smelting indicates a different process than just melting, and it confuses the readers when used to indicate simply melting. :| 

http://dictionary.reference.com/browse/smelt

Sincerely,
Don


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