Precipitate tin from HCl

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GoldUser

GoldUser

Well-known member
Joined
Apr 7, 2022
Messages
81
Location
Vienna
Hey,
I dissolved some tin solder in HCl, which were soldered to BGA chips. What is the best way to get tin chloride back to metallic precipitate? I'm just trying to recycle the HCl and learn a bit, so if the process costs more than new HCl I'm fine with it. If there is a better way to get the solder removed, I would also appreciate that.
David
 
According to the galvanic series scrap iron, aluminum, or zinc should cement out the tin if it hasn't oxidized too badly.

Distillation with sulfuric might let you pull HCl from the resulting ferric / aluminum / zinc chloride.

(Theory only, I haven't tried either--both tin and HCl are plentiful, so no reason to recover them.)
 
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GoldUser said:
I dissolved some tin solder in HCl, which were soldered to BGA chips.
Click to expand...
Those solder balls likely have gold in them

There is gold plating "on the circuit board" where they solder the chip to the board

So - when they solder the chip to the board - the solder dissolves the gold plating & the gold alloys with the tin

The solder also has antimony in it

so - when you dissolve the solder (tin) in HCl - it dissolves the tin - but not the gold & antimony

So the black powder in the bottom of the beaker - after dissolving the tin (solder) is a combination of antimony & gold

The solder from circuit boards can run about (plus/minus) 2 grams gold per pound of solder

You can cement the tin out of the HCl with zinc - but you don't recover the HCl

If you want to recover both the tin & the HCl you need to run it through a (electro) winning cell

Thats the sort story

Kurt
 
Surely it has to do with the alignment of the stars and nothing with statistics.
And definitively not random at all.
Right….

Interesting observation though😏😎

And I forgot.. the colour of the last precipitate of course.

Regards, not David 😀
 
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GoldUser said:
Hey,
I dissolved some tin solder in HCl, which were soldered to BGA chips. What is the best way to get tin chloride back to metallic precipitate? I'm just trying to recycle the HCl and learn a bit, so if the process costs more than new HCl I'm fine with it. If there is a better way to get the solder removed, I would also appreciate that.
David
Click to expand...
Recycling HCL from chlorides is not very plesant process, but it can be done, that is for sure. From three common "cementation" metals (aluminium, zinc and iron), choose aluminium or iron to do this, if you want to recover HCL from chlorides. Hydrated aluminium or iron chlorides decompose much more easily than ZnCl2.
Altough I don´t know if precipitate of tin on either aluminium or iron would be well defined and filterable.

Note that you will also precipitate any lead that is present in the dissolved alloy. Maybe with careful addition of diluted H2SO4 into the mix, you would be able to part lead apart from tin, by creating insoluble PbSO4. Tin sulfate has much higher solubility in water than PbSO4. Need to be tested on small sample before moving to the whole lot.
 
If you just want to remove the tin and not worried about recovering the tin, bubble air through it. Just as our stannous chloride test solution goes bad from absorbing oxygen from the air, the same will happen to just HCl. The tin will form tin oxide and settle to the bottom of the container. It may take a week but it does work.
 
FYI, HCl does not condense like nitric acid does. It is formed by passing hydrogen chloride gas through a spray of water. The water is recirculated though a column that has spray nozzles spraying water. After the pH reaches 0, it is collected and bottled.
 
olawlor said:
According to the galvanic series scrap iron, aluminum, or zinc should cement out the tin if it hasn't oxidized too badly.

Distillation with sulfuric might let you pull HCl from the resulting ferric / aluminum / zinc chloride.

(Theory only, I haven't tried either--both tin and HCl are plentiful, so no reason to recover them.)
Click to expand...
Would be a solution for me. Sadly I cant get my hands on sulfuric here.
 
kurtak said:
Those solder balls likely have gold in them

There is gold plating "on the circuit board" where they solder the chip to the board

So - when they solder the chip to the board - the solder dissolves the gold plating & the gold alloys with the tin

The solder also has antimony in it

so - when you dissolve the solder (tin) in HCl - it dissolves the tin - but not the gold & antimony

So the black powder in the bottom of the beaker - after dissolving the tin (solder) is a combination of antimony & gold

The solder from circuit boards can run about (plus/minus) 2 grams gold per pound of solder

You can cement the tin out of the HCl with zinc - but you don't recover the HCl

If you want to recover both the tin & the HCl you need to run it through a (electro) winning cell

Thats the sort story

Kurt
Click to expand...
Thanks Kurt,
could it be that there would be tin part of the settlement at the end? There is quite a bit of "dust" collected on the bottom of the beaker. I did not heat the HCl to dissolve I just let it sit for a few weeks now.
I havn't read much here about cold HCl dissolving tin.
Which metals are used as antimony in this case?
Would there be some silver or/and copper which is mixed with the tin solder (except gold)?
Do metals in the case alloy together at all?
David
 
Geo said:
If you just want to remove the tin and not worried about recovering the tin, bubble air through it. Just as our stannous chloride test solution goes bad from absorbing oxygen from the air, the same will happen to just HCl. The tin will form tin oxide and settle to the bottom of the container. It may take a week but it does work.
Click to expand...
Thanks a lot,
thats the best solution I read beeing in my situation.
 
orvi said:
Recycling HCL from chlorides is not very plesant process, but it can be done, that is for sure. From three common "cementation" metals (aluminium, zinc and iron), choose aluminium or iron to do this, if you want to recover HCL from chlorides. Hydrated aluminium or iron chlorides decompose much more easily than ZnCl2.
Altough I don´t know if precipitate of tin on either aluminium or iron would be well defined and filterable.

Note that you will also precipitate any lead that is present in the dissolved alloy. Maybe with careful addition of diluted H2SO4 into the mix, you would be able to part lead apart from tin, by creating insoluble PbSO4. Tin sulfate has much higher solubility in water than PbSO4. Need to be tested on small sample before moving to the whole lot.
Click to expand...
I sadly cant get sulfuric. Is there another good solution on how to precipitate lead from an acidic chloride soltuion?
 
kurtak said:
Per the bold print - current (spot) price of tin is $32.70 per kilo ($14.86 per pound)

there is a market for it (spot plus) on Ebay

Kurt
Click to expand...

Oh, I hear you. My friend that makes tin alloy faceting laps has not been enjoying the tin market the last few years. When I'm faceting, tin alloys are great.

When I'm refining gold and ready for some nitric, though, I just want it out of my face :p Props to the OP for wanting to pull it back out.
 
GoldUser said:
Hey,
I dissolved some tin solder in HCl, which were soldered to BGA chips. What is the best way to get tin chloride back to metallic precipitate? I'm just trying to recycle the HCl and learn a bit, so if the process costs more than new HCl I'm fine with it.
David
Click to expand...
I've been dealing with this for a while trying to eliminate tin/lead from my stuff, sulphuric acid precipitates
GoldUser said:
I sadly cant get sulfuric. Is there another good solution on how to precipitate lead from an acidic chloride soltuion?
Click to expand...
I found some old car batteries which contains diluted sulphuric acid, I have filtered it and boiled in on low heat to evaporate the distilled water from it.
 
Yes, acid/lead batteries use dilute sulfuric acid as the electrolyte if you can't source from anywhere else. You can buy fresh from auto parts stores here. It is the most expensive source that I can think of, but automobiles are in every country. It would be hard to regulate the electrolyte even if you have to collect it from old batteries.
 
GoldUser said:
I sadly cant get sulfuric. Is there another good solution on how to precipitate lead from an acidic chloride soltuion?
Click to expand...
We often talk about sulfuric acid to precipitate lead sulfate, but eventually you can use any soluble sulfate to accomplish this :) Plain sulfuric acid is just more convenient and practical, do not add any salts etc. But you can certainly easily purchase pH minus chemical for pools - which is usually NaHSO4 (sodium hydrogensulfate). This you can use to precipitate lead instead of sulfuric acid. Or any other soluble sulfate like sodium sulfate, potassium sulfate (sometimes accessible as fertilizer) or maybe also magnesium sulfate (Epsom salt for magnesium bath etc.).
 
orvi said:
We often talk about sulfuric acid to precipitate lead sulfate, but eventually you can use any soluble sulfate to accomplish this :) Plain sulfuric acid is just more convenient and practical, do not add any salts etc. But you can certainly easily purchase pH minus chemical for pools - which is usually NaHSO4 (sodium hydrogensulfate). This you can use to precipitate lead instead of sulfuric acid. Or any other soluble sulfate like sodium sulfate, potassium sulfate (sometimes accessible as fertilizer) or maybe also magnesium sulfate (Epsom salt for magnesium bath etc.).
Click to expand...
from what type of solutions can I precipitate the lead, beside AR? AP, ....?
 
orvi said:
We often talk about sulfuric acid to precipitate lead sulfate, but eventually you can use any soluble sulfate to accomplish this :) Plain sulfuric acid is just more convenient and practical, do not add any salts etc. But you can certainly easily purchase pH minus chemical for pools - which is usually NaHSO4 (sodium hydrogensulfate). This you can use to precipitate lead instead of sulfuric acid. Or any other soluble sulfate like sodium sulfate, potassium sulfate (sometimes accessible as fertilizer) or maybe also magnesium sulfate (Epsom salt for magnesium bath etc.).
Click to expand...
Never really thought about that. Thanks
 

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