[EPhantom]

So I have looked for an answer for this for a few days now and I haven't found a suitable one for a "civilian chemist". Most of what I found online was of people stating to simply "melt one out"  , but you cannot do that as they both melt together below the melting point of their pure states.

The only other solution that I had found involved a large tub of molten lead at around 500°C, with oxygen and chlorine gas bubbling up from it... Three things of which I do not like.

My overall goal is to take the solder off of circuit boards that I don't care about and separating the tin and lead.

(I want to know how to recycle a circuit board completely and am having huge issues trying to find all the info I require)

P.S. This is not for a class, and I do not know much about chemistry, I have had only one university course, all other info that I know of has been through research.

[Stepan]

If you already separated alloy from a circuit board you can dissolve it in nitric acid. Lead stays in solution and Tin precipitates in form of oxides/stannic acid.

[EPhantom]

To what I see, HNO₃ + Sn  SnO₂ + H₂O + 2NO_x
NO_x refers to mainly NO and NO₂ (to what I can see), both of which are very toxic gasses not very suitable for civilians.

Though the acid idea sounds good... I started looking up some and I think I may have something... but I don't know how to purify anything.

Introduction of Acetic Acid (vinegar acid)

Pb + CH₃COOH = Pb(CH₃COO)_2(aq)
Sn + CH₃COOH = Sn(CH₃COO)_2(aq)
(if present)
Ag + CH₃COOH = Ag(CH₃COO)_2(s)

Filter if Silver Present

Introduction of table salt

Pb(CH₃COO)_2(aq) + NaCl_(aq) → PbCl_2(s) + 2 CH₃COOH_(aq)
Sn(CH₃COO)_2(aq) + NaCl_(aq) → SnCl_2(aq) + 2 CH₃COOH_(aq)

Filter Lead

And this is where I get stuck... the lead and silver are "out" of the mixture, but are now in a different chemical form. and the only way that I can find to safely get the tin in a solid form is to use sodium hydroxide, which would result in tin oxide.

And there is the issue of all the spare fluids and such that I don't know what to do with.

[Stepan]

This is first of all wrong. Second, will cost yo approximately 50 fold mode that just to buy Pb and Sn from a store -never mind recycling. If you can separate solder from the board - just sell it as is. It is very valuable.

[EPhantom]

What is wrong with it? And what would happen if I put solder in a solution of acetic acid then added salt? (I asked a chem instructor at the university here and he said if I could get the solder to dissolve then I could add salt to the mixture because lead chloride is "not soluble")

[Stepan]

Wrong reactions are:
1. Silver does not react with acetic acid
2. Silver Acetate is soluble

Poor choice of reagents:
3. Acetic acid is one of the weakest acids and reaction will take forever
Note. Do not worry to much about toxicity of acids or fumes. The most toxic component in the process will be lead, which is STRICTLY regulated. EPA and local authorities will be after you at no time.

Financial feasibility:
4. If you want to break even, be sure that your final products are at least 2-3 times more expensive than the supplies, and there is a demand on them at your price. So far your supplies, chemicals, energy, are too expensive. And I did not count start-up cost, environmental charges, transportation and storage.
5. I do believe that you can find buyer for lead-tin alloy at good price, with way less troubles.


General Note:
Usually, you start with idea, than do feasibility estimation, than if it is OK, you start thinking about process.