Solder removal

[Weehorror]

I see that HCL will dissolve solder from electronics. Great!

can the tin/ silver be recovered from the HCL to re-use the HCL again before it either becomes saturated or loses potency?

 

[eaglekeeper]

I see that HCL will dissolve solder from electronics. Great!

can the tin/ silver be recovered from the HCL to re-use the HCL again before it either becomes saturated or loses potency?

I would imagine that the silver and any antimony would be in the sediment at the bottom. The tin could be cemented out, but it would probably be highly contaminated.

I can't say how long you could reuse the hydrochloric after you cement out the tin.

 

[Weehorror]

I would imagine that the silver and any antimony would be in the sediment at the bottom. The tin could be cemented out, but it would probably be highly contaminated.

I can't say how long you could reuse the hydrochloric after you cement out the tin.

thanks for the reply EK.

im not interested in keeping the tin, only the silver. That can be filtered and refined. Looking at the RSoM, Iron seems to be the best option for dropping antimony and tin.
does that sound right?

I guess the only way is to find out about the potency issue is to experiment.

 

[Yggdrasil]

I see that HCL will dissolve solder from electronics. Great!

can the tin/ silver be recovered from the HCL to re-use the HCL again before it either becomes saturated or loses potency?

Silver will not dissolve, it will form AgCl and drop out of solution.
Some kind of electrolytic removal might be possible, but I see no upside since HCl is cheap and easy available.

 

[Weehorror]

Ok, I get that. Thanks.

trying to cut down on waste if I can

 

[Martijn]

I see that HCL will dissolve solder from electronics. Great!

can the tin/ silver be recovered from the HCL to re-use the HCL again before it either becomes saturated or loses potency?

Yes it can.

 

[Weehorror]

Yes it can.

That’s GREAT! I love chemistry

if he’s using a 9v battery, that’s 500 mA. Can be easily recreated using my bench power supply. That means I can produce SN to make Stannous test solution

thank you Chemistry Gods

 

[Martijn]

That’s GREAT! I love chemistry

if he’s using a 9v battery, that’s 500 mA. Can be easily recreated using my bench power supply. That means I can produce SN to make Stannous test solution

thank you Chemistry Gods

Depending on how much you have, why make tin out of stannous chloride to make stannous chloride?
Try it first.
Use the same HCl leach until saturated. Bottle it. If there are no other metals dissolved than solder that is. In that case, electrowin.

 

[Weehorror]

Depending on how much you have, why make tin out of stannous chloride to make stannous chloride?
Try it first.
Use the same HCl leach until saturated. Bottle it. If there are no other metals dissolved than solder that is. In that case, electrowin.

Just watched a vid on it and realised that very thing

 

[Martijn]

That’s GREAT! I love chemistry

if he’s using a 9v battery, that’s 500 mA. Can be easily recreated using my bench power supply. That means I can produce SN to make Stannous test solution

thank you Chemistry Gods

If you want clean HCl, use inert electrodes. Try which type do not dissolve. Paperclips will leave zinc and iron chloride in solution.
Set your amps low enough so there are no bubbles forming.
This will reduce chlorine gas being formed and electrodes being dissolved.
All chemistry in a fume hood!!

Martijn.

 

[Weehorror]

So, after the advice. I have used HCL on some small boards from laptop hard drives.

Firstly I did it using cold HCL and waited about 3 hours. There was some reaction and small components have fallen off.

Then I put on my hot plate at medium heat for 1 hour. Made a huge difference.

I’m worried about the pins etc as it looks like the plating has come off.
Is that right or is the gold only discoloured?

 

[Weehorror]

See pic

 

[Yggdrasil]

See pic

HCl alone do NOT dissolve Gold,
but it can dissolve some of the Nickel backing or it dissolves some other base metal that cements out on top of the plating, probably because of the same backing/plating.

 

[Alondro]

Ok, I get that. Thanks.

trying to cut down on waste if I can

I always dump the used acid into more base metal-containing scrap to see how much will dissolve away. There's really no downside to using it until it absolutely can't dissolve anything else. Copper dissolved in it will cement out eventually onto the less reactive base metals, but it'll keep eating up tin, antimony, and lead until it's really saturated. At that point there's so little HCl remaining it's silly to even think about recovering it.

If you wanted to remove those more toxic metals from the solution, you could reduce most of them out with zinc. Zinc chloride is far less toxic than antimony and lead chloride. Tin chloride is fairly low toxicity. Lead you can also drop out completely by dripping in some sulfuric acid or sodium sulfate solution. Lead sulfate is highly insoluble.

 

[Weehorror]

HCl alone do NOT dissolve Gold,
but it can dissolve some of the Nickel backing or it dissolves some other base metal that cements out on top of the plating, probably because of the same backing/plating.

I thought as much.

My experiment was interesting. I filtered the HCL and examned the paper. A lot of grey deposits. I suspect this will be silver and tin. At some point I will treat with Nitric and recover the silver.
In the meantime, I will continue to use a heat gun to depop my boards and use HCL to remove the residual solder.

Thanks

 

[Yggdrasil]

I thought as much.

My experiment was interesting. I filtered the HCL and examned the paper. A lot of grey deposits. I suspect this will be silver and tin. At some point I will treat with Nitric and recover the silver.
In the meantime, I will continue to use a heat gun to depop my boards and use HCL to remove the residual solder.

Thanks

Not sure that will be possible, I guess what Silver there is will be in the form of Silver Chloride.
And Nitric nor other acids will do anything with that.
Probably not worth chasing anyway.