# Attacking Kovar pins with combo H2SO4 and HNO3



## Alentia (Nov 1, 2013)

While it is pain trying to work on kovar pins with only HCL due to too many metals involved, specifically Nickel plate. I am to try and publish results attacking the pins with H2SO4 and HNO3 combo.

I wonder if anyone has already tried this method.

On another thought and I am thinking on experimenting using all 3 acids to obtain clean gold at the bottom during whole reaction, while everything else should be dissolved. The logic behind this theory:

Fe + 2HCl = FeCl2
Fe + H2SO4 = FeSO4 + H2
FeCl2 + H2SO4 = FeSO4 (will drop gold) + HCl (will be re-engaged into reaction)
Au + HCl + HNO3 = HAuCl4 + NO + H2O
2 HAuCl4(s) → Au2Cl6(s) + 2 HCl(g)
AuCl3 + 3 FeSO4 = Au + 3 FeCl + 3 SO2 + 3 O

Iron being represented in Kovar at 50% content should serve as catalyst for all of the reactions to occur. Wonder if anyone tried it already.


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## philddreamer (Nov 1, 2013)

> While it is pain trying to work on kovar pins with only HCL due to too many metals involved, specifically Nickel plate. I am to try and publish results attacking the pins with H2SO4 and HNO3 combo. I wonder if anyone has already tried this method.


I've done it with sulphuric acid/sodium nitrate/distilled water. After digesting the base metals, I digested the "sediment" in HCl/sodium nitrate; Then refined digesting again in AR.
If the pins are too thick or brass, I use the sulphuric cell for de-plating the pins.



> On another thought and I am thinking on experimenting using all 3 acids to obtain clean gold at the bottom during whole reaction, while everything else should be dissolved. The logic behind this theory:...


I've done that, too, but find it counterproductive.

Take care!
Phil


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## Alentia (Nov 1, 2013)

Phil,

Would you expand on your findings, how did it work with NaNO3 and H2SO4, what were the results?

Did you try HCl + H2SO4 on kovar pins? If so, how did it work what were the results?

Why using 3 acids for Kovar pins is counterproductive?


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## chlaurite (Nov 1, 2013)

As the most obvious reason, using all three acids at the same time will dissolve gold.

In fact, it will pretty much dissolve *everything* metallic, with only a few notable exceptions, and the sulfuric will even start to go to town on many plastics.


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## philddreamer (Nov 1, 2013)

> Would you expand on your findings, how did it work with NaNO3 and H2SO4, what were the results?]


Al, I used a formula that Barren Realms shared with me for making some weak nitric, 100 ml water/170 g sodium nitrate/57 ml sulphuric.
I added enough solution until most of the base metals were dissolved. I ended up with gold foils and some dark sediment. After decanting and filtering the solution, I dissolved the foils and sediment in Poorman's AR. I precipitated with SMB; and proceeded to refine in AR.



> Did you try HCl + H2SO4 on kovar pins? If so, how did it work what were the results?


No, I haven't. Just HCl/Peroxide, but its too slow!



> Why using 3 acids for Kovar pins is counterproductive?


I tried that; the problem I find is, you end up dissolving everything and its a pain to recover the gold. I don't like to cement gold, I prefer to precipitate it with SMB; (some day, very soon), I'll be using oxilic acid.


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## Alentia (Nov 1, 2013)

Just tried sample batch of Kovar laden CPUs with H2SO4 and HNO3 - it worked wonders.

CPUs were sitting in in HCL/CuCl2 for about 3 weeks with little or no effect.

<removed any possible traces of HCl prior to treatment>

H2SO4 and 1ml of HNO3 per CPU removed all pins within 3 hours with no heating as H2SO4 reaction is exothermic by itself.


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## philddreamer (Nov 1, 2013)

Very good! 8)


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## moose7802 (Nov 1, 2013)

Just curious if those are pins from CPU's?


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## Alentia (Nov 1, 2013)

Alentia said:


> H2SO4 and 1ml of HNO3 per CPU removed all pins within 3 hours with no heating as H2SO4 reaction is exothermic by itself.



Correction!

Read:

H2O + H2SO4 = diluted H2SO4 about 80/20


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## Alentia (Nov 3, 2013)

Here is the video of the intensity of the reaction. Comparing this to 3-5 days boiling in HCl and than still dealing with messy AR. Reaction was on about 20 min after acids are added. It went even more active 10 min after I have shot the video.

http://www.youtube.com/embed/4loYtEf3rH0

Hope moderator can properly embed the video


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## chlaurite (Nov 3, 2013)

Good video, but a little short - Perhaps you could show the setup, ingredients, and a time lapse to the finish?

If you don't speak English well, I have little doubt you could find someone here to help you narrate (heck, if you can't find anyone else, I'd gladly help with that).


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## Alentia (Nov 3, 2013)

chlaurite said:


> Good video, but a little short - Perhaps you could show the setup, ingredients, and a time lapse to the finish?
> 
> If you don't speak English well, I have little doubt you could find someone here to help you narrate (heck, if you can't find anyone else, I'd gladly help with that).



Sarry claurite, i is in kommunite pipl spik fue inlish kold Kanada. you nou it is veir yite bears liv, vi spik ugundu hir. bat wen you ken help mi this vil veri gut. I si you hav saim nambar post in les 1 yiar, i hav in 3. tis is hau i spik not tranlsator. it huvy for me tu explain tu sam 1 hu did not rid post from start.


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## rickbb (Nov 4, 2013)

Cool, so basically you take 20% sulfuric add 1 ml of nitric per cpu and let it digest away the kovar, then filter out the gold foils to refine?

What is the concentration of the nitric you used?


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## Alentia (Nov 4, 2013)

To fully dissolve kovar you will need about 2.5-3ml of HNO3 per CPU

*WARNING!!!*

The reaction when adding HNO3 is vigorous. Add HNO3 in small portions about 25-50ml to start the reaction in cold solution. Than not more than 5ml at a time or you will risk overboiling. Never perform in more than half full beaker, however I would strongly recommend enclosed reaction vessel with complete vacuumed scrabber. When last 5ml will not produce a reaction, you are done.

On the good note, I just witnesses pins done to foils floating a top from about 70 CPUs in just a 10min and I did have little overboiling into the condenser, as I had added too much HNO3 too fast (25ml). Next time I would rather wait for 50 min but I do not want to see what I saw again.


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## pattt (Nov 4, 2013)

edit: its not to me to advise against this method , sorry

pat


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## Alentia (Nov 4, 2013)

Patt,

You are absolutely correct. That is why I issued warning! In any case, doing it in safe environment and adding 5ml of HNO3 at a time while vessel is half full will not trigger rigorous reaction, it will be contained.

It is about as dangerous as putting 50ml of HNO3 into 250ml beaker with hot HCl filled to the top. Anything we discuss here is dangerous one way or another.

*As a matter of fact, we have to discourage any posts mentioning reactions with HNO3 producing NOx "under fume hood" or "outside" as it does poison our environment.*


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## pattt (Nov 4, 2013)

Alentia,

sorry again , I was too tired when I posted, and to much of a newbie to give that comment, but my intentions where good :lol: 
I know a lot of the things we do or talk about here are dangerous if not executed correctly or done with the right equipment,
but we know some newbies just try anything what they read here or see on youtube without thinking or reading much about it, and I thought
I needed to give a warning in this case, like I said I am to much of a newbie myself to give a warning about things that are beyond my own knowledge :roll: :lol: 
so I deleted it, 1 minute after posting it :lol: 

greetings

Pat


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## butcher (Nov 4, 2013)

pattt,
If you thought I was going to fall off a cliff, I would be glad for the warning, even if you were mistaken.
Nitric acid, its deadly gases, and the violent reactions are dangerous.


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## bigjohn (Nov 4, 2013)

I still think new members should be forced to download Hoke prior to becoming a member. Then there should be a time limit before they can post. I know that sounds harsh but how many people show up here every week asking "how do I get the gold" There are way to many people watching a half done youtube clip and jumping right in. 
Sorry about the rant.


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## chlaurite (Nov 5, 2013)

Alentia said:


> Sarry claurite, i is in kommunite pipl spik fue inlish kold Kanada. you nou it is veir yite bears liv, vi spik ugundu hir. bat wen you ken help mi this vil veri gut. I si you hav saim nambar post in les 1 yiar, i hav in 3. tis is hau i spik not tranlsator. it huvy for me tu explain tu sam 1 hu did not rid post from start.


Pssst - Plenty of people can write better English than native speakers but have crap for pronunciation. If you care, I based that comment on the fact that in at least three posts now, you have shown the most curious habit of omitting indefinite articles in your sentences. Perhaps you do that stylistically, but don't cop an attitude when I assume that you don't have aspirations to sound like Gertrude Stein.

I gave constructive feedback and even offered to help you out. No need to act like a jerk in response.


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## Anonymous (Nov 6, 2013)

Back on topic.

Phil could you confirm for me please what the type of pins were in the 7oz you used in the pictures above please? i.e. the source material.

Many thanks in advance Sir.

Jon


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## philddreamer (Nov 6, 2013)

> Phil could you confirm for me please what the type of pins were in the 7oz you used in the pictures above please? i.e. the source material.


Hi Jon!
I did some recovery and refining, (in two different batches), of very, very high grade pins. The owner of the pins told me:
"The source would be a 20 year old Supercomputer which was decommissioned." They were small, but with a very heavy gold plating.
The yield from each pound of pins was 1 T oz of gold.
The first batch was about 2.5 pounds; the second 1.7 pounds. The yield a bit over 4.25 T oz.
I dissolved the base metal in Poorman's nitric; then refined them twice more in AR.

Take care!
Phil


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## bswartzwelder (Nov 6, 2013)

I have read where some people put their pins in HCl to get rid of the solder. I have also read where some people put their pins in HNO3 to get rid of the solder. Is one method better than the other? Once the solder is gone, placing the bare (well washed) pins in an electrolytic cell with H2SO4 seems to be the method of choice. Pros? Cons? Preferences? I'm just a little bit curious.

Removing foils from circuit boards and leaving the gold is best done by the AP method provided the components and solder have been removed (before using AP) as well.

Bert


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## philddreamer (Nov 7, 2013)

> I have read where some people put their pins in HCl to get rid of the solder.


Hi Bert!
I do too IF there's a big amount of solder, otherwise I won't. I like to inspect each type of material, and then decide the best process for the recovery of values. These particular pins had no solder, and time was of essence, that's why I decided to digest the base metal thru Poorman's nitric. In 4 days I had the final product.


> I have also read where some people put their pins in HNO3 to get rid of the solder.


I don't! You'll end up having to deal with metastannic acid, not good at all! :evil: 


> Is one method better than the other?


HCl.


> Once the solder is gone, placing the bare (well washed) pins in an electrolytic cell with H2SO4 seems to be the method of choice.


Not all the time, IMHO; it depends on the type of pins! For example, If I have gold plated brass pins, or long, (over 1/2 inch), or thick pins, I run them thru the sulphuric cell. These pins were about 1/16th of an inch wide x 3/32 of an inch long! 


> Removing foils from circuit boards and leaving the gold is best done by the AP method provided the components and solder have been removed (before using AP) as well


That's another subject... :mrgreen:

Take care!
Phil


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## Anonymous (Nov 7, 2013)

Thanks Phil I appreciate that.

If it's of any use let me return the favour. From the pic those pins are from the plates that sit between the old pinless superprocessors and the motherboards- in the enterprise servers that didn't have "sockets."

I would imagine you probably knew that anyway but I thought I would take a wild stab in case you didn't. In addition to that, the processors themselves that came out of those were large lumps of ceramic that you could break apart and physically see the gold strands within, in large quantities. They were trading at over $700 per kilogramme last year if anyone could still find them.

Regards

Jon


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## Alentia (Nov 8, 2013)

Can some one with better knowledge of chemistry help with all equations happening during the process. 

Kovar = 54Fe + 29Ni + 17Co

At least one of my derivatives in small amount is CoS2 - insoluble in anything

Fe + H2SO4 = H2 + FeSO4
Fe + 4HNO3 = Fe(NO3)3 + NO + H2O.

Co + 2HNO3 = Co(NO3)2 + H2
Co + H2SO4 = CoSO4 + H2

Ni + 2HNO3 = Ni(NO3)2 + H2
Ni + H2SO4 + 6H2O = NiSO4(H2O)6 + H2 (will this even happen or will Nitrate form first and create chain reaction as below)

I saw the NiSO4(H2O)6 salts being crystallized in aq solution at around 20C somewhat interesting.

The 2 reactions below seems like they are in a chain feeding each other until there are both metals exist, are they?

H2SO4 + Ni(NO3)2 = 2 HNO3 + NiSO4
FeSO4 + HNO3 = FeO + H2SO4 + NO2
H2SO4 + FeO = FeSO4 + H2O

At some point HNO3 or NH3 or both being regenerated from NO2+NO+H2?
Co(NO3)2 + H2SO4 - no reaction I assume, once cobalt reacting with one of the acids, cobalt reaction should stop, does it?

Here are few more pictures of the reaction in progress.


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## mrgoldman (Dec 23, 2013)

Hot Nitric Acid


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## butcher (Dec 24, 2013)

Alentia,

With heating and evaporation eventually the sulfates "WIN" the battle over most of the cations.


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## solar_plasma (Feb 10, 2014)

While reading this interesting thread, I wondered, if it would be of benefit, if we would classify processes in categories of risc like this:

cat1: fx. CuCl2 leaching
cat2: fx. dilluted HCl/Cl
cat3: fx. AR, HNO3/H2O2
cat4: everything which only can be done safely with special setup, that would exceed most small labs fx. CN- leaching

That might make it easier for someone to decide, if he already has the abilities and the setup to try a new process, especially if someone already has some experience to compare with. The point is, we can discuss endlessly about safety, but fact is, a process, that may be self-mutilation to one person, may be absolutely safe to another, examples cyanide, extremely exotherm acid reactions and so on.

Such categories are also used in fire and emergency services and in facilities with special hazards.

What do you think? Could it make things easier or just more complicated?


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## solar_plasma (Feb 3, 2015)

Am I right to assume, that this is as dangerous as the processes we have locked for any discussion. Or is it only dangerous, but can be handled safely in ammounts up to let us say 200g kovar by an experienced....,just as an example, chemistry teacher?

After all I am not satisfied with all cold methods. This kovar can be quite frustrating. Don't know, if this alloy I have is a special kind of kovar invented for the only reason to drive me insane.


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## Geo (Feb 3, 2015)

GSP says this is a forbidden topic. It's in his signature line. This is piranha solution and can not be discussed on the open forum. It is that dangerous.


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## solar_plasma (Feb 3, 2015)

I guessed so. Just wanted to be sure. Thanks, Geo!


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