Alright everyone! Welcome back to Cody's Lab
and as promised,
it's time to refine some silver.
So this is some sterling silver which I bought off eBay.
There's a bowl, some spoons, couple of plates,
a napkin ring
and I'm gonna be refining it
down to fine silver
which basically means I'm gonna remove the copper and
other metals from the sterling.
So let's see how much we have here.
Looks like almost 450 grams
of sterling silver.
Now some of it is marked as high as eight hundred,
and others are marked as low as four hundred.
So it'll be interesting to see how much I actually extract from this.
Hopefully this will be a
pretty representative sample of sterling silver.
all right let's get refining
well that was painful to do because let's be honest the silverware is
probably worth more than the melt value of the silver but the deeds done may as
well make the most of it and turn it into a nice pure silver bar
now the easiest way to process the silver would probably be to dissolve that nitric acid
but on doing a little bit of math and figuring out how much acid i would
actually need something like 800 milliliters
I got a lot of sticker shock and I decided that I would pursue a slightly
different method
I'm still going to use nitric but i'm going to supplement it with some
sulfuric acid, sulfuric acid alone will dissolve silver
it's just incredibly slow and it really needs to be quite hot
so I put a little piece of silver into some sulfuric acid and i heated up to
roughly 200 degrees Celsius and I got it to dissolve a little bit but then when I
took it out it actually reprecipitated some of the silver you see
that black material in there is actually a metallic silver that has come back out
of solution as it's reacting with the copper that was still in the sterling
silver
it's really too slow now, like I said I'm going to be using a little bit nitric
acid and this is a mixture of sulfuric and nitric here as you can see it
completely dissolved it it actually did it quite quickly
here's the reactions that are going on so here's the reaction with the nitric
acid forming silver nitrate and I nitrogen monoxide
this is the reaction with sulfuric acid which does not produce nitrogen dioxide
which is a bonus
and here's the combined reactions then here's the combined reactions with all
the extra stuff crossed out
so in this reaction I only need two moles of nitric acid to dissolve six
moles of silver which is significantly less than
you know that the eight to dissolve six moles so basically what's happening here
is the sulfuric acid is reacting with the silver nitrate to form nitric acid
you can see it right here and that nitric acid think and then go back and
redissolve some more silver
I think i'll definitely use that because the sulfuric acid is far cheaper the
nitric acid
i'm going to add about 500 milliliters of sulfuric and 200 milliliters nitric to this
think that will get me pretty well on my way and I'm also going to try
to capture the gas is coming off and recreate the nitric acid
there we go as you can see the acid is now in its kind of a lot of volume
inside that container but hopefully it'll be okay
you notice that the silver is not really dissolving it is dissolving slowly but
it's not going to really dissolved very quickly until I actually dilute the acid
with a little bit of water
by the way if anyone thinks that I'm adding the acid to the water incorrectly
i will link into the description some of my older videos on the subject
it's reacting as you can see I've got this thing set up
so it's also recovering the acid
so the nitrogen dioxide gas that bubbles
out is going to combine with air to form nitrogen dioxide pretty sure I said monoxide
of the first time which then reacts with water to form nitric acid and more
nitrogen monoxide which can react with more air and more water to make more
acid, at least that's the theory
no guarantees that this
system will survive this run but I might as well try
ok guys i might just be impatient but this is acting like it's reacting very
very slowly
i'm sure i dissolved a lot of silver but i'm afraid i may have saturated solution
so tell you what I'm going to take all of this out of here
all this fluid i'm going to rinse the silver off with clean water to recover all
that stuff that has dissolved and then i'm going to finish it up with the pure nitric
okay so here's the silver
as you can see i'm missing about a hundred grams of it
presumably the extra is right here in this silver sulfate which is not
dissolving
as you can tell also there's quite a bit in this solution that is coming out now
that it's cooling off
as you can see I've cut the pieces into slightly smaller size
that way i can fit them down inside of that two liter bottle
ok here we go here's a 200 milliliters of fifty percent water and fifty percent
nitric acid
i'm going to just add in increments of this amount until the silver is gone
oh yes this is going to react nicely might actually react to fast
yeah i'm going to get in the cooling bath
well guys
there it is have dissolved all of the remaining silver with nitric acid and as
you can see I've got over a liter of silver nitrate solution which appears to
have quite a bit of copper in there
it took about five hundred more milliliters of nitric acid which I sort
of expected which brings my total up to about 800 milliliters which is what I
had anticipated to begin with so
well I had to stop the time-lapse camera because it started raining in fact this
air pump probably didn't fare too well in fact let's have a look at this and
see how much acid we caught for that bubble stone is seen better days
well pour it out of the concrete it should fizz if its got acid in it
yeah it's fizzing nice
it's not super strong but that's a some acid that I've recovered definitely
a benefit to running the gases through water like this is I created very little
fumes you occasionally when i put in another shot of acid it started fumes
getting through but other than that there was hardly anything
maybe build a more sophisticated apparatus sometime you here we are
my silver nitrate and obviously copper solution some silver sulfate which is
not dissolving into water and the silver sulfate along with sulfuric and
nitric acid here
I guess it's time to extract the silver from them alright so I've got a bucket
of warm water here and i'm going to dilute the silver nitrate in the bucket
the a dilution will help make the silver more pure because the copper will remain
in the water and the more dilute I can make it the less likely the copper is of
falling out with the silver also the large volume will help keep any lead in
solution as well
all right here it goes
now we got it diluted down in a big bucket of warm water
you can see that there's a little bit of silver chloride actually forming
because this was a tap water here and tap water especially in this area
contains that chlorine
ok so now this is a pot of salt water that I've made by dissolving some table
salt into hot water let's poor this in look at that creamy white silver chloride
forming as the sodium chloride replaces the silver making sodium nitrate and
silver chloride
give this is a stir
so you'll notice it's actually already starting to darken a little bit it's
because I've got direct some light on it and the sunlight strips the chlorine
from the silver releasing a chlorine gas and reducing it to silver metal which in
the finely divided state is dark and color and actually can actually smell a
little bit of chlorine for me especially because it's hot and the chlorine
doesn't dissolve into the water very well now that it's settled out a little
bit i'm going to pour in a little bit more of this salt water to see if I got
all the silver
now you can see there's a fresh cloud of silver chloride and I'll keep doing that until us
that way we'll know we got all the silver dropped out so I actually brought
this bucket down out of the sunlight because the silver as it was reacting
with sunlight was actually beginning to float because of the chlorine gas
produced
so now that I've taken it out of the sunlight it's all settling down actually
and now let it settle down and is clear
sporting a little bit more of this yeah looks like there's a no more silver
chloride forming so that means I've got it all converted it actually
there you go nice curdles of silver chloride here that actually feels quite
heavy
otherwise it'd be almost like cheese curds and put them in there with that
settle a little bit more
now i need to get the silver out of the solution as well as out of the sulfate
that's down here so I'm going to start by pouring off this solution and hopefully
all the sediments and all this stuff is trying to get rid of will be down here
or dissolved and then I should be able to recover it from this using the the
chloride treatment again you'll notice that the solution is turning blue
that's because the a copper is now no longer in such an acidic environment
it's able to change its oxidation state which changes the color because it's now
got a different electron configuration so i'm going to put the s silver sulfate
over into this jar here so I had some of the set
salty water here and there you go and we'll drop the silver out
you know what I decided that I'm going to actually put this into here because
it's basically the same thing and it'll save me a time to settle everything out
my problem with gloves are they give you a false sense of security and you play
with chemicals you wouldn't otherwise
put your hands into and apparently these gloves weren't totally impervious to the
silver nitrate you see my hands are all stained now so i just got back from
voting in the primaries
the line starts somewhere in the building
way outside
as you can see this solution is now a pure blue color and most if not all of
the silver has settled down to the bottom here just going to pour off the
solution most I can
I've got quite a bit of silver in the bucket
ok so I've just squeezed the silver chloride through this cloth here which
has retained most of the silver and driven out as much of the water as i
could now some of the silver chloride did go through the cloth is now
unfortunately back in the solution but it should settle out over the next
little while and all I go through and recollect it but I definitely have
ninety percent of it right here
now that I've got the copper washed out of the silver I'm going to convert the
silver and silver oxide using a potassium hydroxide the hydroxide will
react with the silver chloride forming a potassium chloride and silver oxide
I'm just going to add in basically an excess you see the black color forming
as the s silver oxide is formed and the smoke coming up is just steam because
this is producing a lot of heat so it appears potassium hydroxide also changes
silver sulfate into silver oxide now that these two are identical substance i
can go ahead and add one to the other to combine them so here it is all of my
silver
I guess you could call it black silver there are some white bits in here
that is a silver chloride that wasn't converted because it was in clumps or
something
fortunately that is just a minority and it shouldn't hurt too much because
silver chloride will decompose into silver upon heating as well it just
releases chlorine gas in fact the main purpose of converting it to silver oxide
was to reduce the amount of chlorine gas produced this lighter bit over here is
the stuff that I recovered from the solution the second time round
as you can see there's not very much of it but certainly there
so now i'm going to put it inside of a crucible cap it with sodium carbonate
sodium carbonate and borax sodium carbonate of course is a base which will
actually help convert the rest of the silver chloride into silver oxide
and it will also help with the flux to help everything
liquid and borax is course to thin it out and i'm also going to cap it with
the piece of this rag here that I used to filter some stuff because this
contains silver as well
this will be a source of carbon to help keep the silver reduced
I'll just kind of set this on top of the milk you ready for the furnace so I know
a lot of you are going to ask about what I do is waste chemicals and mainly what
I've been doing is storing it for later
reprocessing in fact I intend to extract the nitrates from this eventually as
well as any trace of silver that's still left but for now I'm going to destroy the acids
that are they're using some washing soda which is a sodium carbonate
yeah that was a little bit of sulfuric acid in there
hopefully they don't boil over also once i get this totally basic that copper
carbonation actually set a lot of solutions so I'll recover the copper as
well it's probably about a hundred grams of copper in there and then once all the
copper settles out then it will be pretty easy to recover the nitrates to make the text
make sodium nitrate
certainly it wouldn't be something you want to eat but you can certainly make
gunpowder out of it so i got me to some metal dish as you can see I've burned to
get rid of any oils or anything
let's take this
out of the furnace seald we got
molten silver here set this down and get a better grip on it
pour it into the mold
that's perfect
there we go
just about hardened
kinda
there's a lot of gas coming out of it there kind of annoying
puffed up like a marshmallow if it's by the way a lot of people have asked about
how much power i used to do these projects and here's the kilowatt meter
and I noticed that when i started this furnace today
this was that 47 on the end here now 54 so that's what 47 kilowatt hours which I
here in logan add only about nine cents a kilowatt hour
that's a less than a dollar now this is cool down significantly
that set pop this out and see how it looks we go came out easy enough
it's kinda off on the shape it's like the metal deformed a little bit i think
the reason why it puffed up like a marshmallow the way it did was actually
because of the flux i was using would have produced a little bit of carbon
dioxide as a heated up or possibly had a little bit of water in it and gases
dissolved better in hot metals and they do in cold metals
so as it cooled off it bubbled out just like a fizzy drink
here it is
the bar of silver that I made a beat down a little bit but still doesn't look
perfect but I say that's fine see how much your ways
unfortunately it's a little bit too heavy to be weighed on my precision
scale so let's actually use this guy here should be within a gram you know
all right 340 grams which means that i've lost a hundred grams in weight
which I'm hoping is mostly copper in fact i was expecting to lose about that
much do to the stamp marks on the silver that the original silver and also I've
got a piece of silver right here which I actually spilt inside the furnace and is
right around three grams so not not a whole lot was that one percent or so i
got over 10 ounces of silver
that's worth right around $175 i think given the current spot market price and
I spent two hundred and twenty dollars on this including shipping so you know I
lost what fifty dollars a didn't of course the add in another twenty five
dollars for the acid and supplies lost seventy dollars to get a hundred and
seventy-five
well I think it's totally worth it a lot of fun
I learned a lot i'm sure you guys learned a lot as well hope you enjoyed
I'll see you next time