Precious Metal Refining & Recovery, Episode 7: Fining Silver

Precious Metal Refining & Recovery, Episode 7: Fining Silver


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

100 Comments

  1. 9c/kWh? Wow – the price for energy in the US is definetley too low. In germany it's about 0,29 EUR/kWh – thats about $ 0,34/kWh

  2. Bernie Sanders is a communist. History…. Has proven it's failure and utter body count should show that humans do not need or want communism….

  3. What a waste of time it was waiting in line, etc., and voting for Bernie now that the facts are out hey? No matter if everyone voted for Bernie, which they did, Hillary knew your votes were all meaningless the whole entire time and was laughing at all of you. No justice even with knowing she cheated Birnie and all his voters being a completely truthful

  4. I am late to comment however,Cody could you make aluminum foam like is being used to rebuild structures in war zones such as the middle east, by creating a longer lasting gas source within the metal itself?

  5. Or dissolve in electrolytic cell
    No need to cut in chunks
    Use KNO3 for electrolyte
    Cu and Ag go into solution
    K ions go to cathode
    Withdraw KOH solution at cathode
    To start.
    Then Ag Cu accumulate in solution
    But Ag stays metallic at anode
    Next Cu plates out at cathode
    After that
    Ag goes into solution
    And Ag deposits at cathode
    Leaving Ag Ir in anode basket filter
    Come on Cody
    You can do better than that.
    I have great faith in you.

  6. Make a compost shed
    Put chicken poop
    Kitchen scraps
    Weeds and hay
    Wood ashes
    Other urine
    Make your own KNO3
    And HNO3 by electrolysis

  7. "the silverware is worth more then the melted weight of the silver"

    LOL thats not even including how hard it was to extract!!!

    Im not about to get rich from melting sterling silver by the looks of it lol lots of work!

  8. < Sterling silver is an alloy of silver containing 92.5% by weight of silver and 7.5% by weight of other metals, usually copper. The sterling silver standard has a minimum millesimal fineness of 925.>  So if it's not 925 it's not STERLING silver. Correct?

  9. Honestly, you should make a series called "Cooking with Cody" where you try recovering precious stuff from kitchen supplies and kitchen equipment.

  10. Cool vid.
    Silver spot went from around 15 usd/oz when this vid was uploaded up to 20 usd/oz later that year and then back down to around 15 usd/oz again now, with normal/constant fluctuations in between.

  11. 4:40 a easy way to tell if you have saturated your solution with silver. Is to let it cool to room temperature and if any silver nitrate crystals form you will know you have a saturated solution. Just add distilled water to dissolve the silver nitrate crystals.

  12. I'm with you matey I worked as a laboratory assistant in high schools and I just hated working with acids no matter how careful you are I always ended up with holes in my clothes as for Silver Nitrate it was worse no matter how long I wore gloves I seemed to always end up with brown stains on my hands which took weeks to go away no matter how many times you washed them and no matter what you washed them with I know some chemical used to dilute the brown colour but I forget what it was Great videos incredibly interesting despite the loss of funds compared to metal extracted keep it up they are great to watch

  13. What type of silver yield should I expect from Monolithic Ceramic Capacitors? And would it be worth it to include Monolithic Chip Inductors for silver extraction? And If I gather both would it mess up Palladium extraction?

  14. That silverware still looks in good condition, it's actually kind of a shame to destroy it. Silver utensils are what I'd like to use personally.

  15. You often stated that silver chloride will decompose into silver and chlorine upon heating, but you are terribly wrong. I learned it the hard way, I didn't realize that my KOH didn't fully react, leaving most of my silver as silver chloride, trying to melt that gave me some stones instead of silver metal. Silver chloride simply melts into a slag. I had a hard time converting these stones back to silver metal… These are soluble in practically nothing.

  16. Cody you think it’s worth it recovery silver from silver plate using sulfuric acid either from computer or any other thing as long is a low cost on the silver plate

  17. I’m sure you know this, but sterling silver is specifically .925 parts per 1000, lower grades are coin silver and other names.

  18. Hey Cody, Please don't let any negativity from petty people keep you from voicing your political opinions. Maybe you can get involved in the Bernie Sanders campaign if you still believe in his candidacy. You could reach a lot of people. Can't wait to see the Golden Spike success video, dude. Do what you want.

  19. I like it when you do chemistry! Especially when you do it in more than one way. You see so many people doing chemistry one way. When you learn two or three different ways to do the same thing. Things start clicking and it starts to makes more sense. Then at least for me I'm able to retain it better. That's important to me because I watch videos like yours to learn. I know the chances of you reading this comment is slim and chances of you responding to it or even slimmer. Nevertheless I still wanted to tell you. Thanks for the Videos

  20. nice video, what about to use sodium or potassium cyanide to dissolve silver and get silver cyanude
    ? what the process would be ?

  21. At the end you talk about how much money you lost by comparing the cost of the items and the chemicals. I say maybe you should open a reatail store. somehow they can justify spending $8 million to avoid paying $400 thousand.

  22. Awesome science! Political science is also important to note. That many people in a line waiting to vote on a weekday (I assume) is discouraging voters:[ hopefully there will be more polls in the next primary…

  23. I've been wanting to get into precious metal reclamation for a while thanks for showing that you don't need a lot of fancy equipment but a good knowledge of chemistry and the scientific method. also, I'm definitely not but first.

  24. That gas is the dissolved oxygen being released. They call it spitting. Silver is known to absorb oxygen when molten unless a reducing atmosphere is present. The cure is to keep oxygen from diffusing into your silver (reducing atmosphere) or let the silver cool slowly giving the oxygen a chance to exit. Did you see little cavities from the trapped oxygen in your bar when it was water-jet cut?

  25. Bernie lol, hopefully you’ve matured a bit on the political front lol. Great video, just found your channel I’ll be goin through your catalog 🤘🏻

  26. Hi Cody, watching your videos for a few years now, keep up the good work!

    I've got a question, do you know of an acid which will solve silver but not copper/brass?
    I'm working on an experiment with relais, but the silver is 'rivettet' to the brass/copper

    Hope hearing from you.

  27. My high-school chemistry experiments were like: "I will now take Sodium chloride two highly dangerous metals which when in an ionic bond are rendered neutral. I will suspend it in solution of a liquid form of dihydrogen oxide. What we have here is aqaeus solution suitable for fishy to swim in."

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