Hcl to dissolve tin

[Yggdrasil]

I have some copper flat pieces that were sent to me - they have what looks like a layer of tin on them. maybe they were electrical related parts.

what would be the best way to dissolve the layer to leave the Cu ? Hot HCl or another method ?

Just curious on this.

Thanks.

GOG

HCl should fix it.
And as long as you don't disturbe the surface so it takes up Oxygen it will not attack the Copper.

 

[grainsofgold]

thank you. Should it be heated ?

 

[Yggdrasil]

thank you. Should it be heated ?

The reaction will be faster, but the risk of taking up Oxygen and thus attacking the Copper increases too.
So it all depend on your needs and your end use of the product.

 

[Shark]

That layer of tin may be silver, be sure to check first.

 

[Golddigger76]

Flat copper pieces, plated with a silver coating that are possible buss bars or electric related parts.

Well then if that is what they are it's most likely tin or silver if hydrochloric acid will not dissolve then it probably silver and will need to be stripped with a different acid like sulfuric or nitric.

 

[J.Najam]

Hello everyone,

So this was my first depopulation using HCL, note the type of Rams that are there. I'd already removed the chips and ICs manually, but to understand the process with HCL better I decided to dissolve the solder on the se boards and a couple of ICs as well. It went well, started with about 600 grams ram boards with the majority of MLCCs still attached.

I've attached the condition of boards I decided to soak, 600 grams of these in a mason jar with 500 ml HCL, covered with another beaker (fume trap) trap solution sodium carbonate + water and some sand ( just felt like it would be better) to hold up those gases. Anyhow since it was my first experience, I did not know when it would stop so I continued for about two hours to let it soak and shook the bucket every 20 -30 mins to offset some sort of reaction.

Now as can be seen :

solution decanted into a 1L beaker with some mud on the bottom, possibly Au and Sb which sits at rest. The issue at hand is the orange bowl. This contains ICs, MLCCs, capacitors , diodes, some grey sludge, possible some black au sludge as well as stickers on rams and some solder masking that also came off while scraping away the components.

Does anyone have any idea how we separate these?

 

[Yggdrasil]

Hello everyone,

So this was my first depopulation using HCL, note the type of Rams that are there. I'd already removed the chips and ICs manually, but to understand the process with HCL better I decided to dissolve the solder on the se boards and a couple of ICs as well. It went well, started with about 600 grams ram boards with the majority of MLCCs still attached.

I've attached the condition of boards I decided to soak, 600 grams of these in a mason jar with 500 ml HCL, covered with another beaker (fume trap) trap solution sodium carbonate + water and some sand ( just felt like it would be better) to hold up those gases. Anyhow since it was my first experience, I did not know when it would stop so I continued for about two hours to let it soak and shook the bucket every 20 -30 mins to offset some sort of reaction.

Now as can be seen :

solution decanted into a 1L beaker with some mud on the bottom, possibly Au and Sb which sits at rest. The issue at hand is the orange bowl. This contains ICs, MLCCs, capacitors , diodes, some grey sludge, possible some black au sludge as well as stickers on rams and some solder masking that also came off while scraping away the components.

Does anyone have any idea how we separate these?

The ICs can be separated and then pyrolized and incinerated.
The rest MLCCs, and other small components is best suited for a smelting operation.

And there is no Antimony in there so I assume you mean Sn not Sb.

 

[Yggdrasil]

Hello everyone,

So this was my first depopulation using HCL, note the type of Rams that are there. I'd already removed the chips and ICs manually, but to understand the process with HCL better I decided to dissolve the solder on the se boards and a couple of ICs as well. It went well, started with about 600 grams ram boards with the majority of MLCCs still attached.

I've attached the condition of boards I decided to soak, 600 grams of these in a mason jar with 500 ml HCL, covered with another beaker (fume trap) trap solution sodium carbonate + water and some sand ( just felt like it would be better) to hold up those gases. Anyhow since it was my first experience, I did not know when it would stop so I continued for about two hours to let it soak and shook the bucket every 20 -30 mins to offset some sort of reaction.

Now as can be seen :

solution decanted into a 1L beaker with some mud on the bottom, possibly Au and Sb which sits at rest. The issue at hand is the orange bowl. This contains ICs, MLCCs, capacitors , diodes, some grey sludge, possible some black au sludge as well as stickers on rams and some solder masking that also came off while scraping away the components.

Does anyone have any idea how we separate these?

Look at this thread for the smelting.
https://goldrefiningforum.com/threads/refining-mlcc´s-for-palladium-and-silver.30953/post-325028

 

[J.Najam]

Look at this thread for the smelting.
https://goldrefiningforum.com/threads/refining-mlcc´s-for-palladium-and-silver.30953/post-325028

I've already gone through this thread. Thanks for the redirection

However this -

And there is no Antimony in there so I assume you mean Sn not Sb.

With due respect, Ive read this countless times over the forum that solder contains +-5% antimony with 95% tin. Hence, I came to this conclusion and was on to reading about digestion of antimony to recover gold.

 

[Yggdrasil]

I've already gone through this thread. Thanks for the redirection

However this -

With due respect, Ive read this countless times over the forum that solder contains +-5% antimony with 95% tin. Hence, I came to this conclusion and was on to reading about digestion of antimony to recover gold.

Maybe a little but not much so it should not pose an issue as far as I know.
Most likely Copper or Silver since the antimony should most likely be dissolved.

 

[FrugalRefiner]

Antimony will not dissolve in HCl. Many use 95% tin / 5% antimony solder to make their stannous chloride. The tin will dissolve. The antimony will end up as an undissolved powder in the bottom of the container.

Dave

 

[Yggdrasil]

Antimony will not dissolve in HCl. Many use 95% tin / 5% antimony solder to make their stannous chloride. The tin will dissolve. The antimony will end up as an undissolved powder in the bottom of the container.

Dave

Ok, the search I did said that it will dissolve in strong HCl. But Antimony triChloride will not be soluble in water.
So the acid needs to be concentrated maybe?

 

[J.Najam]

I checked up and there was one reference by KURTAK that antimony does not dissolve in nitric or he doesn't think it would be affected by AR. Then I did a google search it stated that antimony dissolves in hot nitric.

Which of these is even true?

I was thinking to dissolve the black sediment in warm HCL + 30% H202. Then drop with SMB. But again, not readily sure which path to take on this any suggestion would be highly appreciated here.

Thanks for your time

 

[Yggdrasil]

I checked up and there was one reference by KURTAK that antimony does not dissolve in nitric or he doesn't think it would be affected by AR. Then I did a google search it stated that antimony dissolves in hot nitric.

Which of these is even true?

I was thinking to dissolve the black sediment in warm HCL + 30% H202. Then drop with SMB. But again, not readily sure which path to take on this any suggestion would be highly appreciated here.

Thanks for your time

Just did a new search and this came up:

Antimony does not react with hydrochloric acid in the absence of oxygen.

Anyway, it is minute amounts and do not react much with the acids we use.
So there should not be any issues.

 

[Darkthirty]

I checked up and there was one reference by KURTAK that antimony does not dissolve in nitric or he doesn't think it would be affected by AR. Then I did a google search it stated that antimony dissolves in hot nitric.

Which of these is even true?

I was thinking to dissolve the black sediment in warm HCL + 30% H202. Then drop with SMB. But again, not readily sure which path to take on this any suggestion would be highly appreciated here.

Thanks for your time

Solder I use for stannous is 80/20 Sn-Sb. Black leftover residue is Sb

 

[J.Najam]

Anyway, it is minute amounts and do not react much with the acids we use.

Then how can one be sure if we have put all the gold in solution if we start with digestion for the same?

Solder I use for stannous is 80/20 Sn-Sb. Black leftover residue is Sb

My process contains solder from Ram boards that has been discussed many a times as an Au/Sn alloy.

 

[Yggdrasil]

Then how can one be sure if we have put all the gold in solution if we start with digestion for the same?


My process contains solder from Ram boards that has been discussed many a times as an Au/Sn alloy.

Antimony is a Semi-metal and as such I do not think Gold will cement on it.
Just run your leach until it do not react anymore.
For foils and powders it should be pretty obvious when it is finished.

 

[J.Najam]

Just run your leach until it do not react anymore.

Right. Got it, just doing this one for the first time so needed some clarity. Need to go through a painful process of separating the grey goo first and then will proceed with this.

Thanks for the feedback.v