Hi everyone welcome back to my lab, so many of you will be excited to know that I am bringing back the precious metals
Refining and recovery series so one thing that has been requested many times by people is to refine some of this
Silver Solder here
This is the stuff used in plumbing to replace leaded solder the silver is added to it in about one to five percent by weight
to help the mechanical-
properties of the Solder.This is actually a sample that a fan sent me and not just one-
Or even two, but three separate people have sent me rolls of solder to refine
that's-
So obviously you guys want to see this done. So anyway since this is a new season. I guess of this
series, I would like to mention again that I am not doing this to make money like-
There's no way I'm gonna make back any sort of money-
refining these rolls of silver-
At best, I'll probably recovers the few grams of silver worth just a few dollars
And that's not going to recoup my processing even if I got this stuff for free-
I'm mostly doing this series to explore the chemistry that-
said my first idea for extracting the silver from this was just to dissolve the whole thing in some 'Muriatic acid' or hydrochloric acid
Hydrochloric and Muriatic are the same thing by the way, this is mostly tin
Probably like 95% tin and tin is soluble in the hydrochloric acid, but silver is not-
So it'd be fairly simple to do that
But I did the math and it looks like to do a quarter pound of this stuff
it would take almost a half a gallon of acid if I account for evaporation losses and stuff because
The tin dissolves rather slowly, so I think what I'm actually going to do is I'm going to set up an electrolytic cell here
I'm going to set this up and I'm going to use primarily electricity to oxidize the tin and
Perhaps recovered over here and actually be left with a purified tin sample
Which is something that I might be using in another video as well. Let's weigh this over here
That looks like a hundred and nine and a half grams which
Is supposed to be a hundred and thirteen grams on the roll so yeah, that's probably about right?
Let's take this back over here. I'm gonna wind this into a coil, and we'll make our electrolyte solution
So this is what I've come up with here
I've just wrapped this into a coil around a piece of half-inch dowel
and I've bent the ends so I can hang it on the edge of this glass dish a little bit of space underneath, so
Materials can fall off of this and not short things out so now for the electrolyte
Which is primarily going to be water. Which is generally the case.
And add enough water to completely cover the coil here. I'm just gonna add a splash of muriatic acid
now this is mostly just because it conducts electricity really well and
Has lots of chlorine.
if there's chlorine in the solution the silver will not be soluble, I suppose you could use salt but
If you've got muriatic acid, you may as well cause it'll actually react with the tin a little bit so now
I'm going to hook these up
I've got 16 volts direct current between these two terminals here
Let's put the negative electrode over there on that stainless steel spoon
And the positive over here on the coil of metal that I want to destroy
There we go. We got some hydrogen gas bubbling off
Soon, we should see some tin being precipitated out over here now if you look at the reactivity series of metals
you'll find that tin is much lower on the activity series, so
That'll be the first thing to be oxidized and pulled off of this the first thing to go into solution
copper, bismuth, silver, all that stuff's gonna fall out of the solution and settle onto the bottom of the
Jar here. Look at those crystals forming, isn't that pretty?
Unfortunately those are very likely to short things out. That's what I got so far
I
Didn't get to it in time
Must have shorted out
fortunately it acts as its own fuse, so...
It wasn't really that big of a deal
So this has been working rather
well, you can see this coil is crumbled into pieces and I have processed quite a bit of the tin over
In fact this has only taken about an hour and a half to do that. There's a lot of tin left here, but
easily three-quarters of it has been transferred, so I've actually just unrolled this
Spool of wire here, and I'm gonna do another one of these
So we can do a whole half a pound of tin, so another
one hundred and fifteen point six nine
grams, so apparently there is some variation on the weights of these
spools...
Anyway, I'm gonna set this up,
and were gonna process another one. Now would you look at that? I have electroplated some bubbles...
Okay, looks like that's about as done as we're gonna get for this step as you can see it's eating my wire right off there...
Let's pull the spoon out of that
Get the last of that tin off of it...
So as you can see over here I've got quite a pile of tin
In fact I'd say I've transferred over most of it
And what we've got left in the dish...
There's a couple of chunks of it in there still
you can kind of see
But primarily it looks like I've just got like copper and silver powder
So tell you what I'm gonna do is, I'm gonna pull out the bigger chunks of tin
After I break off all the little bits of silver and copper from them
And I'm just gonna let this sit in the acid overnight.
I may even dump off some of this and strengthen the acid a bit to dissolve away these
stray pieces of tin crystals
and then...
once we got that, then we can process it to extract the
silver from the copper.
And I think what I'm just gonna do here is, I'm just gonna take this
tin solder that didn't
convert and I'll just weigh it,
and
subtract it from the total
I'm sure I could melt it back into a piece of wire and process it again, but at some point, I'm just wasting my time.
So it's the next morning and presumably the acid has destroyed most of the tin
There's probably some tin still left in here, but is definitely
Reduced in quantity and so the majority of what we have left here is probably copper and silver
And I think what I'm gonna do with this is I'm going to decant off all of the acid I got a little jar here
I've been pouring it into
and I'll be saving the
Tin chloride for later use... Now, I need to get rid of the copper..And to do that
I've got several things I can do first is nitric acid of course
but unfortunately nitric acid and
tin do not really get along.
Makes an insoluble white gunk that is very hard to deal with. I could use sulfuric acid,
but then tin doesn't dissolve in that very well either
I could take this and roast it in fact commercially if I was doing very large quantities
I think that would be the way to go you know just basically smelt the silver out
But I think today what I'm going to do is just simply add in some more muriatic acid
and then I'm going to add in some hydrogen peroxide to oxidize the copper...
And that should dissolve most of it, little bit of hydrogen peroxide here...
Okay.
Looks like that's working. I was afraid that maybe this silver would cause it to decompose too rapidly,
but really all I need to do is get a little bit of the
copper chloride to form and then just oxygen diffusing in from the air will take care of the rest.
As the copper chloride kind of acts as like a catalyst to help
the copper further
decompose. This will take a while though, so
Guess I'll come back in...
I don't know...
Six or eight hours? In case you're wondering I do have a fan, and it is currently going. Normally though
I turn it off when I'm filming because of reasons which I hope are obvious.
So anyway, we've got...
this which appears to be done. And...
I guess that is silver in the bottom there.
It seems like not very much though, so I suspect the pH of this must have been too high...
And I've run into an issue of the silver chloride actually dissolving even though it's not supposed to.
So let me actually pour most of this liquid off into this other container here...
and let's uh...
see if this contains silver chloride
Simply by diluting, the acid, should also turn from green to blue... Yes, very nice.
Okay, any silver precipitating?
Okay, there's a little bit of white clouds in there. There's not very much...
I guess this solder didn't have all that much silver in it
Let me uh... let's wash this off
So that's really all of our silver... After letting it settle out, washing it, settling out again, I'm left with this... Now
this is primarily silver chloride...
but there's not very much here. Now It might look like a bunch, but, having refined silver before I know that
there's, you know, it really expands when it's in water like this, so this is probably much less than a gram here...
But we'll put it into a crucible and furnace it down anyway...
I don't know what's wrong with this furnace...
It just refuses to get hot, and it got hot for a while, and then it started cooling back down...
So there's the problem... Looks like a wire burned off.
Look at that right there, the wire goes down and comes back up...
What'd it do, break off?
And then just arc out and until it stopped functioning?
I ought to have this sent in and have it warrantied. This is a brand new furnace, it shouldn't do this... It's still giving an error...
Guess I'm gonna have to see if I can send it in to have it warrantied...
In the meantime, it did melt the silver...
How about we just break it out of this little crucible instead of pouring it out.
[Hammer hitting crucible]
Oh hello bug!
Go away! So you can probably see right here that there are some beads of silver... Not very much is it?
So let's set this over here on my
weighing paper...
There we go...
Looks like around a tenth of a gram...
Now, of course my recovery is not going to be a hundred percent...
I lost some because the furnace wasn't hot for long enough, and the you know microscopic beads didn't come together
But I don't think I lost 90 percent.. All right, I would imagine ten to thirty percent is what my losses are here...
so...
either I'm a terrible chemist...
or...
the companies that make the solder, only put enough silver in them to say that they did...
[Chuckles]
[Breathes in]
I mean... If the silver didn't make all that much difference and the price of silver was extremely high then, wouldn't you?
Anyway, let's weigh these pieces of solder that didn't get destroyed in the electrolysis...
Just to see how much we need to subtract from our totals here, so then get some numbers. Okay about 29 grams...
While I'm at it I may as well melt down my ball of tin here... Looks like I broke my dish...
[Whispers] Pour this out...
Let's weigh this tin that I recovered. Looks like a hundred and ten grams, so
I started with around with 200 grams of solder that was destroyed with the electrolysis...
So I recovered, you know, around 50 percent of the tin...
Now, that kind of recovery I would expect, because, well a lot of the tin oxidizes while you..
are melting it because is so thin and I have all the tin oxide still I can still recover that some acid and stuff
But it may not be worth my time. I can tell you right now, that this tin is worth way more than the silver was...
[Laughs]
See, it's around...
you know ten dollars a pound?
That's around a quarter pound right here, so, two, three dollars in tin...
few cents in silver...
Anyway, let's put my gloves back on...
Let's do some math...
Definitely wouldn't want to get any of this math on my hands. Some nasty stuff isn't it? So...
the silver...
recovered is
point
106 Grams...
Point. Oh dear. That's really zoomed out. Zoom this in a little bit here. So the solder that I started with
225 Grams
Solder that was left over...
Was 29 grams... so that means the solder that we actually processed...
was
196 Grams
so
point
one, zero
six divided by
196
Both of those are three sig figs that's kind of cool...
that equals point
zero zero zero five four...
And then converting that to percent that's point zero five
four
percent silver... now of course
that means it had at least that much silver in it, right?
They on their website, I think it said that it contained one to five percent silver
So I am seeing you know roughly...
that really
Wow, that's like a hundredth of what they said they've got in there, something's up.
I may return to this project at some point. I would love to get one of those xrf
handheld devices that we were using back up in the university, because then I could just check my
waste materials and just see
hurt hurt just the solder itself for instance and see how much silver is got in it
At least I was able to recover it and show you guys the chemistry
Hope you enjoyed I'll see you next time.
[Uplifting Music]