Hcl to dissolve tin

[Jmk88]

Just be careful with the fumes Sir, above 50 degrees (c) and it starts to get quite heavy!

Don’t have any of your metal equipment in close distance either...

Good luck!

:wink:

 

[Williamjf77]

That’s 60degrees F but yeah the hcl fumes is what started this whole thread really. Honestly I was just trying to avoid leaving the fume hood blower going all night. Actually I better go turn it on now.

 

[Williamjf77]

Ok just checked the solution. It is reacting nicely at room temp.
I knew most of what I read says hot hcl but if it can be done reasonably without heat that’s great for me. I didn’t like the thought of venting fumes in the summer when everyone is outside so I collected my materials during the warm months and am processing now. Plus I had to put a new roof on the garage.

I do have a makeshift exhaust out the window top. It works good. I can’t bring myself to cut into the beautiful roof I just put on. Eventually I will and do the whole scrubber setup. I scored a nice 2500 something cfm squirrel cage blower, when I install that I’ll do a proper roof exhaust.

But thanks for the safety warnings. One can never be reminded enough times about the hazards we deal with, be it a first timer or an old timer,

 

[butcher]

But thanks for the safety warnings. One can never be reminded enough times about the hazards we deal with, be it a first-timer or an old-timer,

How true, old=timers may know better but they can easily become too relaxed or careless in their practices, or neglect to continue their study in the safety aspects...

 

[Shark]

Could someone explain how heat and cold affect the solutions? I know they slow down when cold and usually speed up when hot, but what is actually going on that causes the effect? Thought I would ask here as it seems to follow along pretty well.

 

[FrugalRefiner]

Energy. When we warm something, we add energy. When we cool it, we remove energy. In a warmer solution, all the ions are more energetic, so they bang into each other more often and with more force. If you toss a baseball gently at a piece of drywall it will probably just bounce off. If you throw it as hard as you can, you may put a hole in the drywall.

Göran can probably provide a much more elegant explanation.

Dave

 

[butcher]

I can not explain it but I can guess that adding heat energy would have a lot to do with speeding the reactions, with an increase in rate or number of high energy collisions,the physical reaction of an increase in molecular movement and the action in the solution, the production of the gases increase, solubility change, the concentration of the solution which also concentrates the remaining unreacted acid or base or other reactants in the reaction.

Or just because it is like this old man, it just works better in warm weather than cold.

 

[Shark]

Or just because it is like this old man, it just works better in warm weather than cold.

Now that I can understand,

 

[anachronism]

If you imagine a big jug of water with a load of table tennis balls (or similar in it) at room temperature- those balls are pretty much sitting there. Now heat the water to boiling and look at the balls. 8) 8)

That's pretty much what happens with reactions. The atoms are smashing against each other much more frequently like the balls in boiling water.

 

[Williamjf77]

Well it was taking too long without heat but I believe it would have done the job if the temp stayed @60-70f .

I think tomorrow after it is done I will distill off the HCL and save the stannous Chrystal’s

 

[Williamjf77]

Here is another safety tip from this newbie

Safety labels
Cheap from Amazon now a days and it makes my space look less like a meth lab. Or at least a safety conscious one.



Edit: I tried to rotate the pic but couldn’t

 

[butcher]

Williamjf77,
Excellent advice, you should also keep a book of the MSDS sheets for all of your reagents...

 

[Williamjf77]

I find I’m more likely to label stuff properly if the labels are pre made and right there. I think I paid 6$ for the roll.

 

[Jmk88]

William, (and anyone interested)

Here is what sodium hydroxide does.

Pic 1. Gold jewellery in boiled water

Pic 2. 3 minutes in

Pic 3. 15 minutes in

Pic 4. 20 minutes in

After an hour I will remove this and place it in fresh water after rinsing it off with a hose (whilst wearing goggles - very important after being in lye).

I will then add approximately 50 grams of hydroxide again and boil for another hour. You will notice the water stays almost clear on the second wash indicating the removal of all solder.

The brown in pics 2 - 4 is tin and lead precipitation, mainly lead as this is vintage material. Now I will not need to worry about hcl use, fumes, separation, incineration etc. I simply pour off solution, place my material in my choice of removal acid and proceed. This will leave you with almost completely clean foils.

Lye will remove any organic oils as well as most synthetic contamination (if any). So the brown you see is mainly lead precipitation.

Hope this was helpful.

Clarity

Pic 1 - bottom

Pic 2 - 2nd from top

Pic 3 - 2nd from bottom

Pic 4 - top pic

 

[Williamjf77]

That’s interesting. I may give it a try on the gold filled I have to refine. The last batch I did I incinerated then nitric and I had problems with what looks to me like tin and lead and then the silver content was more than 10% of the batch.

What does lye do to silver?

 

[Jmk88]

Yes silver will react with sodium hydroxide; gold will not. Silver oxide will be formed. Not enough to worry about so pour away with the solder.

The second wash in caustic will not produce much solder at all but still let it go for an hour. You’ll notice a muddy colour looking water by the end of the second.

But most is taken off by the first within 30 minutes.

Gold filled is normally set on copper or stainless steel. Occasionally silver but mainly these two.

Kind regards,

 

[FrugalRefiner]

Why did you put an entire watch including the movement in there?

Dave

 

[Jmk88]

Because it’s easier than hammering it apart.

You remove that and all the glass is removed too. You will lose a bit of gold where the solder breaks away but it’s better than having a huge mess.

Regards,

 

[Jmk88]

I have about 12 watches in there, 25 bangles, 15 chains, 7-10 rings, bracelets.

In total I have 4kg which I hope to get 80-120 grams of pure gold from. That in the picture is approximately 200grams of jewellery and you can see the water is literally black after half an hour. I placed 10 grams of dried solder (previously incinerated) which was mixed with gold flakes from a previous batch in hcl Sunday night.

Not even a third has dissolved.

See my point?

 

[Shark]

A whole watch? What karat is it?