Hcl to dissolve tin

[butcher]

But copper chloride would just dissolve the tin, lead, and copper and steel wouldn’t it?

Yes but not without problems or conditions.

Removing the bulk of the unwanted metals mechanically will remove many of the problems.

Tin even any acid is trouble, it is somewhat easier to deal with in a chloride solution, it still can cause trouble filtering reacting with other metals... it is best to remove it mechanically or by some other means if possible...

While you can deal with the iron, stainless, lead and tin, and other base metals in a cupric chloride leach it is best to keep them limited or out of the solution as much as possible.

Tin in a chloride solution hydrolyzes become hard to filter, its salts are amphoteric and react with other metals and their salts and the solution with its own red-ox reactions, and is a well-known thief of gold in solution...
stainless is made to make iron resist acids or oxidation...
Iron in volume in a solution converts a copper cupric chloride leach into a ferric chloride leach...


The more trash in solution --> the more trash out.
The more trash in solution -->the harder to get values out.

 

[Jmk88]

What Butcher said.

 

[snoman701]

Nobody is disputing dissolution rate other than you. You seem to be having a circular argument trying to prove you are doing something worthwhile, you are not.

I run gold filled straight in nitric, then refine the foils with AR....I cannot imagine doing it any other way with my current capacity.

Most mid tier "refiners" do not refine gold filled at all, just assay for gold and silver and sell it on, usually melted in to their karat so they get better rates for it.

Personally, I've done enough with nitric. I can do a few kg load in a day, but it creates a lot of waste. I'll very likely switch to electrolytic copper in the near future, but that's not a conversation for this thread.

Miller chlorination or electrolytic copper cell is going to be the next most utilized method...but nobody that I know of is putting jewelery in lye.

 

[Williamjf77]

It’s also hard to compare dissolution rates unless you are using the same Molarity and Particle size. A solid nugget of tin is going to take a while to dissolve even in any solution compared to powder or film.

I think hcl works good for e waste solder because it can get access on most sides. A solder joint in jewelry is probably more of a very thin film by capillary action.

 

[Shark]

I run gold filled straight in nitric, then refine the foils with AR....I cannot imagine doing it any other way with my current capacity.

Most mid tier "refiners" do not refine gold filled at all, just assay for gold and silver and sell it on, usually melted in to their karat so they get better rates for it.

Where is that thumbs up emojii?

 

[Williamjf77]

Not being able to get nitric must be a pain. Is that a UK thing or is it just real hard to find, or real expensive?

 

[Bertho]

I Wrote: How can I dissolve the lead chloride & stannous chloride from the leaching process?
I got tiny specks of gold mixed with it that I am trying to filter out and recover.

Butcher wrote:
Is this a filtering problem?
Or
Are you talking about salts in solution or the gold mixed with an insoluble powder and scum?
it is hard to help without knowing what you have done or what you are doing or planning to do, or what we have... without seeing or knowing what all is happening it is difficult to answer some of these questions...
-------------------
Thank you so much Butcher for a very detailed answer.
A quick summary: I was solder leaching old HP PCBs with gold plating in HCl. The thermostat failed and the PCBs were in boiling HCl for a day. Some gold actually came off as tiny specks and is now mixed with the lead & tin sludge. Presumably also some dissolved copper. There is no silver in the mix. The PCBs were free from components.
Net result: I am trying to recover the gold flakes mixed with the sludge. If I could dissolve the sludge I then could filter it. Maybe I should be thinking about it the opposite way: How to properly dissolve the gold while mixed with the sludge?

 

[butcher]

Many times a choice would depend on conditions...

Have you tried putting the salts back into solution with HCl? Most of the metals that were soluble before should redissolve.

 

[g_axelsson]

If you have something that is hard to dissolve then the solution might be to dissolve the gold and filter / decant off the gold chloride solution.

A trick Harold often advocated is to incinerate the material before dissolving the gold. It made it a lot faster to filter afterwards.

You might lose some gold, but at some point you have to decide how much time and money are you going to spend to get that last part of gold.

Göran

 

[Jmk88]

This is interesting and I will be reading about it all night. Very rock and roll for a Friday... for a 30 year old.

Lead-tin solders readily dissolve gold plating and form brittle intermetallics.[9] 60/40 Sn-Pb solder oxidizes on the surface, forming a complex 4-layer structure: tin(IV) oxide on the surface, below it a layer of tin(II) oxide with finely dispersed lead, followed by a layer of tin(II) oxide with finely dispersed tin and lead, and the solder alloy itself underneath.

I think Butcher May know whether this layered structure maintains its integrity when aiming to remove. If so, it may explain why so many people have issues with it? I have a whole filter paper full of tin/lead contaminants and am planning to place in strong acetic acid. I will post the results. May not be for a week or two.

 

[Jmk88]

I believe today was also a massive learning experience.

I understand why my comments may have stirred up some controversy and criticism. I believe the key to the difference in opinion comes down to discussing hard or soft solders.

I now understand why soft solder would not be best processed the way I discussed; and thus I apologise to anyone that may have upset.

It was shown to me today that hard solder is broken down to silver chloride when processed in Copper Chloride with the higher reacting alloyes such as zinc and cadmium dissolving along with the base metals.

I understand that what I was perceiving as Lead was silver chloride.

However, we did play around with soft solder and hydroxide as well as hcl and I still reserve and opinion which I’m hesitant to express and reignite discussion on that.

I wanted to acknowledge publicly the above and hopefully show I’m learning and a good rate. Again, I apologise for anyone that took what I said as being ignorant and can see why that may have occurred.

Thank you to anyone who had input into this discussion, it has led me to here.

Kindest Regards,

 

[Shark]

British Dictionary definitions for ignorant

ignorant / (ˈɪɡnərənt) /

adjective

1. lacking in knowledge or education; unenlightened
2. (postpositive often foll by of) lacking in awareness or knowledge (of)ignorant of the law
3. resulting from or showing lack of knowledge or awareness: an ignorant remark

I think we have all been there, but we come here to educate ourselves and (hopefully) not be as ignorant as we once were. A good many of us, myself for one, have no where else to learn about refining but from the internet and spend many hours here in the hopes of making up for not having a real person (in person) to study under. Often it is hard to put into words what we have in our minds as well.

"The journey of a thousand miles begins with one step" but is sure does leave many more steps to reach that destination......... Welcome to refining.....

 

[butcher]

I would not use vinegar or acetic acid, yes they may dissolve lead easily, so what, you can nail a picture on the wall real fast with a large sledgehammer with a healthy swing of the tool. if I posted all of the reasons why I personally would not try and dissolve lead as a soluble acetate I would fill a book.

I can understand your confusion, with the terminology and the term solder.
Brazing and soldering are two different things the processes are different so are the solders or brazing alloys used are different, many of the terms are used interchangeably.

soft solder or soldering is done at fairly low heat, hard soldering or brazing is done at a much higher heat (getting copper piping cherry red hot...), welding is done at an even higher heat where we melt the metals together into an alloy of a welded bead...

Brazing,
silver solder can be an alloy of 5-95% silver with an alloy of copper, zinc, nickel, manganese, cadmium, tin, silicon, phosphorous. sulfur,... Termed silver solder or brazing solder, this alloy melts at a very high temperature. and is used in brazing not used in soldering (these terms are also used loosely and often times interchangeably in the field of work).
In high silver alloys of the brazing silver HCl would not work well as the silver will form a passivated silver chloride crust, (although alternately would be useful to use to dissolve copper pipe and leave the silver brazing)...

Soldering,
silver solder here is normally alloyed with lead or tin and other lower melting metals to make a low melting alloy like a lead-bismuth tin...

I can also understand you thinking that you were correct in some of the points of the debate of using caustic versus HCl, not knowing this difference between soft and hard silver solders...

It is only until we can admit when we are wrong that we can learn to be right. nothing wrong with being wrong, we are all sometimes, it is when our pride gets involved that it makes us wrong, and blocks us from overcoming our ignorances.

 

[Bertho]

butcher wrote: » 14 Nov 2019, 23:18
Many times a choice would depend on conditions...
Have you tried putting the salts back into solution with HCl? Most of the metals that were soluble before should redissolve.
I boiled is twice in HCl and got rid of some stuff.
After looking at your solubility info, I have been boiling it in water several times and it is slowly improving.
Bertho
----------
g_axelsson wrote: » 15 Nov 2019, 04:16

If you have something that is hard to dissolve then the solution might be to dissolve the gold and filter / decant off the gold chloride solution.

A trick Harold often advocated is to incinerate the material before dissolving the gold. It made it a lot faster to filter afterwards.

You might lose some gold, but at some point you have to decide how much time and money are you going to spend to get that last part of gold.

It is an interesting challenge and definitely not worth it financially but I like to learn.
Bertho

 

[Williamjf77]

I can say for myself when it comes to Internet forums and text only conversations I try to never judge an attitude or anything from a couple posts. A lot of text can come off as condescending or ignorant or cocky when in fact if it was said face to face it wouldn’t sound like that especially when dealing with international forums.

On the subject of the thread, it turns out my cpus in hcl actually was done the first night, the chips that still had pins on them were being held on by some other mechanical way and they easily came off with a little agitation.

 

[butcher]

That is a big problem we cannot see each other it makes communication very difficult and can result in a lot of problems, the written word alone can easily be misunderstood, we also cannot see what the other is doing or has done, so we also have those obstacles to overcome, so we start of blind, and deaf (we can not hear a voice or tone of speech), now if we also have to get past the misspelling misuse of terms, language barriers.,,

It is hard enough to communicate with all of our senses and not end up in some kind of problem in understanding each other...

It is a wonder we can get anything done together.
edited --death with deaf
:lol:

 

[Jmk88]

Thank you all.

I will keep you posted of my process.

I am always happy to skype etc. Even if it’s at a late UK time!

Kindest Regards

 

[Sunnyket]

Getting back to the original question of this thread --- NO - it is not better to dilute HCl when dissolving tin - it will slow down the reaction AND if made to dilute it will actually cause the tin to precipitate out as stannic tin (the white paste)

if anything - when using heat (which is not needed when dissolving tin) which can/will vapor off HCl you would want to add "more" HCl to keep the HCl from becoming dilute

You "only" need to use hot HCl for dissolving solder IF the solder is an alloy of tin & lead --- that's because cold HCl does not react well with lead - but when lead is alloyed with tin the lead will dissolve along with the tin when the HCl is heated

Then - when the solution (tin/lead dissolved in hot HCl) is cooled - the lead will precipitate out as lead chloride crystals - which dissolve again when heated

Therefore - if the solder is tin solder (most if not all newer electronic scrap) - (mid 90s & newer) use HCl without heat & don't dilute it

older electronic (70s into early 90s) it is more likely the solder is lead/tin alloy therefore heat MAY need to be applied to dissolve the solder
Kurt

Hello kurt,
I need help in this
I've metal powder (dust) contains
34% gold
58% tin
4% lead
1.5% antimony
1% iridium
0.5% osmium

What should i do first?
(I started reading hokes but not completed yet)

 

[Yggdrasil]

Hello kurt,
I need help in this
I've metal powder (dust) contains
34% gold
58% tin
4% lead
1.5% antimony
1% iridium
0.5% osmium

What should i do first?
(I started reading hokes but not completed yet)

Where does this material come from?
If it had not been for the Osmium I would have dissolved it in HCl whivch would leave me with Gold and some Ir.
But the Osmium would have “scared” me off.

 

[Sunnyket]

Where does this material come from?
If it had not been for the Osmium I would have dissolved it in HCl whivch would leave me with Gold and some Ir.
But the Osmium would have “scared” me off.

Hello sir,
Thanks for reply

Material came from AR process. I missed HCl bath before AR that was my mistake
And when precipitate with SMB i got this powder.

What does osmium do with the solution?