Hi everyone, welcome back to Cody's Lab.
This is episode 2 of my precious metal refining series
and today we're going to be doing some actual gold jewelry.
Now I got my super inaccurate, Walmart scale here
and a lot of you had mentioned that there's a little
switch on the back that you can push
to switch it between ounces and pounds,
to grams and kilograms.
Which I have done and uh,
obviously messed up the zero here.
But now, the scale is much more accurate.
You can see that it
measures in 300 grams. See..
See this is the kind of thing that I have to deal with.
Look at this.
Okay, so now it measures in grams, which is much
more accurate than the ounces it was measuring in.
And I have here, is some gold jewelry
which I will weigh up...
You can see I've got 32 grams of gold jewelry here
which is 14 karat.
That's of course including the gemstones.
So I guess the first thing I need to do, is get rid of those stones.
And by the way since the last episode,
I've actually ordered a precision scale
like the one you'd use in chemistry,
which measures out to the miligram
so I'm pretty excited for it
and hopefully it'll get here before I'm doing
all these things that I need a bit more precision for weighing
the smaller bead that'll come out of it.
You can see I've removed the gemstones from the rings.
Now I know you guys are going to ask
so this one is definitely a diamond,
this is a pearl,
and this here is an amethyst.
I'm not quite sure what these two are
but I'm a geologist and I'll probably figure it out soon.
You might notice there's a little bit of weight lost
this was 32 grams, now it's 31.
That's because there was a lot of dirt inside
of this ring here that I dug out
so, definitely lost a bit of weight there.
The way that I got the gemstones out
most of them I was able to just pry the little fingers up
and then the gem stone fell out nicely
this one here, I had to open with a pair of cutters.
Okay, so now let's see what these weigh without
the gemstones.
Should be pretty easy.
It's now 28 grams, so it's lost about 3 grams
worth of rocks.
Now some of these rocks might be valuable
and I'll keep them around for later projects
but until then let's start working on this gold.
Now this ring here you'll notice is actually
a different color than the other ones.
Because this is actually white gold
you can see it's a silvery color rather than the gold tone
and uh,
that is because this is alloyed with either nickel
or palladium.
And uh, I guess it'd be a good idea for me to check
to see which one it is alloyed with
whether nickel or palladium
I have a pretty easy test for that.
You see, palladium is a platinum group metal
and if I heat it up,
it will not oxidize.
Whereas nickel will oxidize almost immediately.
So let's warm this up a little bit in this fire
and see what happens to it.
If it oxidizes, that will confirm that it's nickel
and I'll just add it to the other metals, 'cause it won't really change anything.
If it's palladium, I'd have to do a different whole process
in order to uh, purify it
So I'd have to make another video out of it.
Yeah, it's definitely oxidizing.
It's definitely discoloring from the fire.
So it's definitely Nickel.
Oops. [laughter]
Now since this is 14 karat gold,
and 24 karats is pure gold,
this means that this is about 58% gold.
If I multiply that by 28, which is the weight of the gold that I have
you can see that I have 16.3 grams,
if I managed to extract all of the gold from it.
And that is of course assuming that the 14 karat is accurate, which sometimes it's not.
Now unfortunately since this is 14 karat gold,
I can't just put this in the aqua regia and then expect it to dissolve
because the silver content, which is what the base metal here is.
Uh, this one has nickel so I could probably drop this one in, and be fine.
But these ones contain silver,
and silver does not dissolve in aqua regia.
In fact if there's any more than about 10% silver
the silver will actually form a coating on the gold, as soon as it hits the aqua regia.
And it will make it either not dissolve, or it will dissolve very, very slowly.
So in order to be able to refine these I'm actually going to mix the gold with some copper
approximately an equal mass to the 14 karat gold because I want to decrease the gold content down to about 25%
That way I can actually dissolve the metal in nitric acid
and that will leave me with gold powder
silver and copper in solution
silver of course will be easy to recover
and I'll have some gold powder to work with.
Okay here's the gold along with a bunch of copper
let's put this together
and I'm going to put it in the furnace and melt it down.
I'm going to pour it into water
to disperse it into tiny droplets to make it dissolve faster.
Okay here goes.
[molten metal hitting water and boiling]
There we are
and yes as you can see I cleaned the stairs
I saw a few comments about that people wanted me to clean up all those leaves so I didn't start a fire or something
so while this was melting I did that
another thing that people were commenting on a lot was the fact that I showed my mistakes in the last video
and you know what I'm going to do that because if you guys make the same mistake at least you'll be able to see how i solved them
anyway I'm going to add a little bit of distilled water to this
because dilute acids work more efficiently
you know it will use less acid overall
it may work a little bit slower
now I'm going to add in some nitric acid, this is straight nitric no hydrochloric
so it should only dissolve the siver and copper
leaving the gold behind
which is exactly what I want.
Now I'm just going to add a little bit in for now
and then when this is all used up I'll add a little bit more
just like when dissolving the gold in aqua regia this produces nitrogen dioxide gas
so it's better to do this outdoors where it's well ventilated
as you can see I'm busy dissolving it away
I've been using 50% strength of the 70% nitric acid
and every now and then I pour off the material
that way I can keep the acids concentration up
that way I can dissolve it at maximum speed
and with the greatest efficiency in the acid.
Now you can see that this stuff is already begun to crumble up into a brownish powder.
I like to crush it up a little bit between batches you know to flake the gold off to make it react better
After dissolving away the copper and silver with nitric acid you can see what I'm left with
A brownish powder which is almost pure gold
Now I could melt this down right now and have probably 98% gold
Or I could run it through acid
and be able to make uh maybe 99.9% gold
I think I'm going to do the second one
now since this is very finely divided the acid should dissolve it very quickly
since is suspect that there is about 15 grams of gold here
I'm going to add in 60 milliliters of hydrochloric acid
[liquids being poured]
There we go
Let's just fill it right to the 60 milliliter mark
[glass clinking]
and now I'm going to add in some nitric acid,
but I'm not going to add it in all at once I'm just going to add it in like a ...
couple of milliliters at a time
until the gold stops dissolving
There we go I've dissolved the gold
with what appears to be
5 milliliters of nitric acid.
See, like I said, you'll be very surprised at how little you actually need.
Okay, so the next day and this has been dried out.
so hopefully there's no nitric in there
also hopefully I didn't get it too hot and bake the gold out.
[liquid fizzing]
and ya know what, I think we're good. It looks like it's all dissolving
Right here is the solution that I poured off of the gold
This contains all of the copper and hopefully the silver
Now I need this beaker so I'm gonna transfer it into this other container for now
And actually let's dilute this with a bunch of water and let's precipitate the silver out
now you'll remember silver is incredibly insoluble if there's chlorine in the solution
so I got some hydrochloric acid here
let's put this in, and you'll uh watch the silver fall out
[liquid pouring]
there it is
looks like cottage cheese is clumping up in there
that's your silver chloride
I don't know if you can see,
but there's just a tiny little bit of silver in there
and that's what I was trying to remove by putting it through acid again
Now I'm going to pour in some boiling water
here we go
ya see there's three things that affect settling rates
the first one is, of course, the particle size
Now I can't really change that
and the particle size here is going to be incredibly small
in fact, positively microscopic
The second thing that I can change is the
temperature, because the higher the temperature, the faster it'll settle out
that's why I'm using boiling water
to make this as hot as I can get it
And the third thing that affects settling rates
is the uh
dilution
like, the more concentrated the solution, the slower it will settle out
because the particles like run into each other on their way down
Now I'm going to use my preferred method
of precipitating the gold
and that is to make some sulfur dioxide
and bubble it into the solution
Sulfur dioxide is of course made by reacting sodium metabisulfite
which came from stump remover
Not the potassium nitrate stump remover
They actually make stump remover with sodium metabisulfite
I'm gonna put some hydrochloric acid into the metabisulfite
and that is going to produce sulfur dioxide gas which is going to bubble through the solution
and cause the gold to precipitate out
there you go, you can see the sulfur dioxide bubbling out already
[bubbling, sizzling sounds]
there we go, looks like I dropped out quite a lot of gold
very nice
there's still a bunch in solution
so I'm gonna set it here to stay warm as it settles out
could take quite a while
and once it settles out I'm actually going to check it with stannous to make sure I got all the gold out
uh
so I just took a piece of tin metal
ya know, mettalic tin and I put inside this bottle with some hydrochloric acid
very simple, and then I let it sit for a few days
hydrochloric acid dissolves the tin in the solution
and I have a solution of acidic, stannous chloride
which is exactly what you want when testing for precious metals in a solution
let's uh demonstrate this real quick
okay so here's some uh pure water
i'm going to add some stannous chloride to it, and you can watch what happens
so I put in quite a bit there
give it a stir
but as you can see
there's no color change, whatsoever
I have a little bit of gold chloride here
which i'll
put in using my stir stick
here we go
let's put in a little bit of that
now you can see the color's changing
see that?
see it kinda gets to a purple color
that's because it precipritates out a colloidal gold
as the tin is another thing that will make gold fall out of a solution
looks like all the silver's all settled out
as you can see i've washed most of the copper
out of the silver chloride
and now, to check to see that is silver chloride and not lead chloride
I'm going to hit it with my laser.
Alright,
and you should see it darken
because the light actually knocks the chlorine atoms
off of the silver
leaving silver metal
in a finely divided state, which will be a darkened color
looks darkened to me
so now let's turn this into silver metal
it's probably not really worth doing, but uh
I think you guys wanna see it anyway
first thing I'm going to do is mix it with potassium hydroxide
to convert the silver chloride into silver oxide
and then
I've never tried this before, but I'm going to try reacting it with fructose
to see if that'll actually turn it into pure silver metal
if not, I'm just going to smelt the silver oxide
and that'll leave a nice bead of silver anyway.
Okay, so here's the potassium hydroxide
just dump this in
oh look
there was a little bit of copper in the solution
oh well
It won't be pure silver
but we'll definitely convert this back to metal
yeah this should uh turn to a nice dark color
yep becuase it's turning it into silver oxide
and the potassium hydroxide is taking the chlorine
making potassium chloride
and it's leaving the oxide for the silver to take
alright, let this work for a little while
now let's see if that sugar trick will actually work
here's some fructose
and I think I need to heat this up a little bit
you know what, I think it is actually working.
Uh, camera can't see anything because it just fogged up
now the particle size is not any different than it was
so it's not gonna look like shiny or anything
but it's definitely whiter
so I can definitely tell now that it is in a metallic form
so this is metallic spongey silver here
Welp, I'm just going to melt this down now
okay, we're up around 2,000F
let's pull it out of there
take this
have to do this one-handed, I know...
Let's pour it out
There you go,
nice little bit of silver.
That's really not very much is it?
Yeah...
That's probably less than a gram...
So, while the silver was melting
I took the liberty of washing and drying out
the gold powder.
As you can see here.
Let's put this in the crucible now
and uh melt it down, too.
Look at that.
it almost fills it
actually it does fill it
yeah there it is
it'll melt down
can't wait to see that button
it's gonna be big
Alright, I think the gold should be melted by now.
Let's have a look at it...
Well, I can have a look at it
There it is.
Think my uh tongs popped and some rust fell into it, but
otherwise it looks pretty good!
Yeah, look at that
it's a shame about that little blemish on the top
but uh, you know what
I'd say it's pretty...
Well... pretty!
Oh, it's got a cavity in the back, too.
Maybe I cooled it too soon...
Anyway,
let's go weigh it
nice fat bead of gold
put it on the scale
17 grams
well the scale's not super accurate
so that's probably just over 16 then
very nice
So, here's what I've gotten so far
you can see that I took that little blemish out
of this bead here
I just put it in some hydrochloric acid and dissolved the rust away
and uh this is the bead I got last episode
and heres a little piece of silver
now there's much less silver than I was expecting
and I was a bit confused about that until
I looked over at my waste jug here
and look at this
that...
is some silver chloride in the bottom of it so
what must've happened is uh
again the pH was too high for the silver to drop out or something
and when I pour it off into this bigger jug
it all settled out
yeah so there's probably
quite a bit of silver in there still
at least I know where it is
I'll extract it out of there eventually
there's a couple more things i'd like to mention
first that uh Daniel Dezdan
sent me some uh catalytic converter material
he sent me some catalytic converter material
so I'm gonna extract the platinum from this
so which means that uh
this series I guess is no longer exclusively gold
so I'm going to change the name of it to uh
"Precious Metal Refining"
and the last thing I'd like to mention
it that uh
I'm just an amateur.
I'm doing this for fun.
I'm by no means a professional
and if you want to do this yourself
I recommend doing some extra reading
and research on your own.
and I definitely recommend this book here
trying to get to the title page
written by C. M. Hoke
"Refining Precious Metal Wastes"
It's a very good book
it's kind of expensive
I managed to find this on eBay
but uh
I'll definitely link a place on the internet when you can get a
free copy of this
anyway
hope you enjoyed
I'll see you next time!
♫♫ [outro music] ♫