# Pins in Nitric acid



## hazza001 (Dec 30, 2011)

Hello all,

Upon dissolving some pins I got out of some laptops in nitric acid I noticed the formation of a white solid at the bottom of the flask. i believe this solid to be lead nitrate, if so how do I go about removing this from the solution?
do I;
Decant copper nitrate and filter the solution incinerate the powder along with gold foils then wash in HCl, filter and dissolve the foils?
Or
dissolve the solids with the gold in AR filter and then drop the gold then re refine?

or none of the above :mrgreen: 

thanks 

Harry

should be able to upload some pics tomorrow to help


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## butcher (Dec 30, 2011)

Lead nitrate is not very soluble in water, but it is, you can try and wash it from foils(will take a lot of water for small volume of powder), or you could get the lead as a chloride later as you suggested, lead chloride is fairly insoluble in cold water, but very soluble in hot water.


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## qst42know (Dec 30, 2011)

If you put all solids into solution in AR you could drop the lead as sulfate with a bit of sulfuric. Then it will filter out without the many rinses.


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## Smack (Dec 31, 2011)

Sounds more like Tin to me.


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## butcher (Dec 31, 2011)

.Solder, high in tin and lead, this is something you do not want in solution with values.

These should both be eliminated as much as possible, (mechanical separation as much as possible), pretreatments of heated HCL is a good method (tin in solder dissolves into solution, breaking down the solder, copper or gold is not attacked by HCL alone, lead will fall to bottom as lead chloride white powder).


Tin in nitric makes a gel very hard to filter.
Tin will almost dissolve in concentrated HCl, but will lock up gold in solution and is still somewhat of gel and will give trouble filtering.

Lead is will dissolve in nitric acid slowly, but is only slightly soluble (slightly soluble in water).
Lead is insoluble as chloride, (almost insoluble in cold water, but is much more soluble in boiling hot water)

If you have fine gold in powders or flakes with very much solder (lead and tin in powders or solution (tin being the bigger problem, in my mind), you have not done the pretreatment methods very well (so you need to practice that more next time).

Now it will take more work to deal with the lead and tin now.

Incineration of these dry powders to red-hot, but not melting.

(If these powders are chlorides, or were treated with HCl, neutralize them first by washing in a sodium hydroxide solution, and rinse well to remove salts {gold in chloride salts are volatile when heated}).

Incineration, helps in several ways, burns off oils plastics or carbons, removes previous acids as gases, will oxidize base metals, (here tin being oxidized is important, as tin oxide dissolves better in HCl wash we will use later).

Many way's you can do this I will show one way:

After neutralizing powders with dilute NaOH (if needed to neutralize and remove chloride salt water), and rinsing powders.

Wash them from jar (using squirt water bottle into a white corning ware dish on a hot plate (solid cast iron heater plate), turn hot plate on low, 

use pipette to remove the water but not picking up powders, allow powders to dry on low heat, after dry crush powders, I used a Pyrex pestle, raise heat slowly on dry powders (some powders may fuse and become syrup again, these we want to dry under the higher temperature but not so hot that they bubble and splash out of dish, after they calcine and dry again (acids driven off), we will re-crush them). Other powders or gold flakes may just dry and not fuse, raise heat to high, with lid on dish let heat on high till no more fumes evolve, remove lid with a hand held propane torch on low heat with the tip of the torch being careful not to blow out powder, as they heat you can bring in flame of torch closer, get powder glowing red hot, stirring with stainless steel (old knife for purpose), keeping these powders hot and stirred exposing them to air (oxygen to oxidize the base metals in this red heat), (keep powder red hot 30 minutes, if powders were sulfates heat red hot longer), put lid on dish and let cool, 

when cool add HCL to cover powder, boil, put heat on low, add just a little water to dilute some, let powders settle, decant the hot HCL with pipette, but do not pick up powders, if HCL is very colored (HCl wash hot will remove most all the tin, and lead as will hot water rinses) repeat HCL wash, rinse with water several times until clear on decanting water, leave powder in dish on low to dry again (and incinerate again if you plan on using nitric to remove more base metals the HCl wash did not get), (the powders can now be washed in nitric acid if needed ) or if gold can be dissolved in dish, only reason to remove values from dish is for filtering solution into clean jar for precipitation of values.


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## niteliteone (Dec 31, 2011)

Butcher,
Thank you.
I was looking for a good process to incinerate values so i could then remove tin that found its way into a nitric solution I'm working on.

OK I screwed up and put some pins into the nitric forgetting about the tin. My bad  

But thank you again
Tom C.


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## hazza001 (Dec 31, 2011)

Thanks very much :mrgreen: 

I filtered the solution and put the powder on the hotplate in a pyrex dish and incinerated it with the propane torch all was going well.
I added it to HCl and it turned into a green solution still with the powder still in the flask. I then washed in water and boiled it, it went from green to grey with the powder still in the flask (odd thing was bubbles formed on the surface and turned vivid green when i swilled the flask they dissipated, reaction with the air maybe?)

I took a small sample and managed to dissolve it in AR and I think this is what I might do then filter and precipitate and re refine. Its a tiny amount of gold and not really worth loads of effort but hey, gold is gold  

i have put the rest of the pins in AP and will leave them till most of the base metals are gone, I will then wash incinerate and further process with nitric, filter, wash dissolve in AP and precipitate.

thanks again for your help will show the results when I'm done 

Harry


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## Chimera (Jan 20, 2016)

Hi guys I need some help please, I'm trying to wash gold dust with 50% nitric acid and 50% distilled water, I'm boiling it and the gold dust come in to liquid again can some one tell me what I'm doing wrong please? Thanks guys


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## rickbb (Jan 20, 2016)

Why are "washing" gold dust? And why in nitric?


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## Barren Realms 007 (Jan 20, 2016)

Chimera said:


> Hi guys can someone please explain me why I'm boiling gold mud in 50% nitric acid and 50% distilled water and is coming in to liquid again? This things is driving me crazy!! :x [youtube][/youtube]



Probably because you still had traces of HCL in your powder that caused your gold to go back into solution when you washed the powder in your nitric. Best way to eliminate any traces of HCL or nitric in your powder is to incinerate the powder. Better yet don't wash your gold with nitric, it's not a good idea.


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## FrugalRefiner (Jan 20, 2016)

Chimera, posting the same question in different sections is not necessary and it's against forum rules, as it scatters information all over the forum. I've deleted your other post and moved the answer you received in the other thread here.

Welcome to the forum. Please review our rules in the Board Policy-------This should be read by everyone post. You might also benefit from reading through the Tips for Navigating and Posting on the Forum thread. Be sure to follow all the links.

Dave


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## massiwe (Apr 7, 2016)

Hello again
I'd like to go back with similar question.
I've disolved 1,2 kg of gold plated pins in nitric acid (about 3l). those pins are from IDE connectors, motherboards, etc etc. anyway soldered.
First I've boiled 3x400g in hot HCl about 1h per batch to disolve the tin, then boiled 2x in hot water to remove HCl. And then HNO3.
I've ended with nice 5l of filtered blue liquid (probably Copper Nitrate and Iron Nitrate together) and two bekkers:


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## massiwe (Apr 7, 2016)

So I have about 100ml the grey sludge mixed with gold.
But this material is more clay than gel, so it is no tin or metastannic.
I've tried to dissolve that in concentrated HCl, HNO3 and H2SO4:




later I put some water in and still no result. This material is insoluble in those acids.

My question is... any idea what is it? And how to get rid of that?
Best regards Piotr


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## patnor1011 (Apr 7, 2016)

Incinerate it before trying to dissolve it again. It will help, believe me.


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## patnor1011 (Apr 7, 2016)

It seems the same like I got when dissolving pins in nitric, I would say that tin is culprit here. A lot of pins are made from copper/tin alloy so quick wash in HCl will only remove solder and not tin from the body of a pin itself.


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## massiwe (Apr 8, 2016)

This morning, after 24h later, the last probe with HCl disolved all. I could say the rests of HNO3 in the "clay" react with HCl and create AR.
I have no gel as well so suppostly it is no tin.
I'll go on this weekend and post later some more pictures and results 8)


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## Wingedcloud (Apr 25, 2016)

Hello,

I'm currently doing a batch of pins from several origins too.

My process is as follows:

- Get the pins in nitric and some water (be sure you use a tall beaker cause nitric reacts very violently with pins, risking a boil over, as you may know already);
- Decant most part of it and filter the last part (I leave th white paste on the bottom of the beaker);
- Get some more nitric running to make sure everything base metals on the pins are dissolved;
- Let decant one more time and filter the same way;
- At this moment, I should have tin nitrate (that devil), some salt of lead (maybe lead nitrate) and gold foils;
- Next, I'll do a 50/50 solution of sulfuric and water to dissolve tin and probably get lead as lead sulfate, which I can filter later (gold foils should not dissolve on this);
- Filter everything and then put the foils on some HCl, adding HNO3 in increments (creating AR) so not to have to deNOX later;
- Precipitate gold with SMB, or, in my case, PMS (potassium metabisulfate);
- Filter and melt to get a nice button 

I'm using this line of processes considering what I read in Hoke's book. Maybe some more experienced forum member can validate/deny this process as something that can be done with gold plated pins.

Best regards,
Winged


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## saadat68 (Oct 28, 2018)

butcher said:


> .Solder, high in tin and lead, this is something you do not want in solution with values.
> 
> These should both be eliminated as much as possible, (mechanical separation as much as possible), pretreatments of heated HCL is a good method (tin in solder dissolves into solution, breaking down the solder, copper or gold is not attacked by HCL alone, lead will fall to bottom as lead chloride white powder).
> 
> ...


Hi Butcher
Processing pins: 
1- dissolve tin and some base metals in boiling hcl
2- washing with hot water
3- washing with sodium hydroxide solution(???)
4-incenirate
5- dissolve base metals with nitric acid
6- dissolve gold
Look at step 3 please
Do we need do this step for pins? Because they are flakes in this step(not powder) and gold is in metal form 

Just yes or no is enough for answer 
Thanks


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## butcher (Oct 28, 2018)

You are correct, there is no need for the hydroxide use with the pins.


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