Hey guys my name is Jason with Mount Baker Mining and Metals and today we're going
to be doing some experiments with some different flux recipes, smelt things some
sulfide rich concentrates. Here's those sulphide rich concentrates, and we're
gonna do four different tests to try and find the best solution for fluxing
sulphide rich concentrates like off the shaker table from a sluice box or
something. So let me get the four different samples set up and then we'll
walk you through them. So this is going to be our sulfide sample here, I've homogenized
it as best I can, shook it around, rolled it around and so
now we're going to weigh out 75 grams per sample. Here's our four samples. This
is 250 grams of borax, 75 grams of sulfides, and 50 grams of lead as a
collector. This one is 250 grams of Chapman's flux with 75 grams of
sulfides and 50 grams of lead. This one is 250 grams of Chapman flux, I'm going
to roast the sulfides, turn them into oxides, and there's also 50 grams of lead
in there as a collector. And this one is 200 grams of soda ash, 50 grams of silica,
50 grams of lead, and then the 75 grams of sulfides not roasted. And to this one
I'm going to add the iron rod and we can talk about that a little later when
we're doing that one. But there's our four, our four samples and we're gonna do
them in this order, borax, Chapman's roasted, and then the iron nail. And then
here just real quick, these are the crucibles I use. I don't remember the
size I think they're like a number three or something, but they can hold you know
the the three or four hundred grams and stuff we're going to be putting in them
and and they've been working real well for me. And I get them from Legend
Refining there and in Nevada. And I'll put a link to their website in the
description below. And then here's our here's our sad looking little furnace
here. This is just a wrap of kaolwool and I put a lid on top. It's seen better
days, I've gotten over a hundred smelts out of this thing. And then here, you know,
when it gets so bad it won't hold the heat I'll just cut out another piece of
kaolwool and put it in there for for a replacement. so this kaolwool holds up
really well and it's really cheap so that's what I've been using.
So here's the first charge we're going to do this is the borax and the sulfides
and it's important when you're starting to smelt that you don't you don't end up
with your your crucible more than about two-thirds or three-quarters full
maximum because as this heats up its gonna release a bunch of gas and this
whole charge is gonna boil and foam and froth and stuff so you don't want to you
don't want to have it boiling over your crucible you want to keep enough room
that the charge can expand and then and then once it's all up to temperature it
quiets way down and it's actually be about a third that much volume. Okay our borax charge is
up to temperature now. We're gonna take it out of the furnace and pour it into this cone mold
and all the dense material is gonna go right down to the bottom the lead and the matte
and that slag and the borax, it'll a float on top and it'll differentiate it into
three layers. And then when it cools they can turn it over and knock it over knock
it out of there and see what we got in the bottom.
So here's our borax charge in the cone mold, and it's real glassy and it's
pulled in the in the middle there which is typical of real acidic or glassy
slags. And I'm cooling it down in the snow right now because when I use lead
as a collector metal it, you got to make sure that it's below the melting
point of lead or if you knock that thing over and tip it out and the lead still
molten they just get molten lead splashing everywhere. So two things with
the cone mold it's important to heat it up and dry it out, but don't get it so
hot that the charge fuses it to the steel when you pour it. And then if
you're using lead or some low collector metal, a collector metal with a low
melting point make sure it's cool enough that the metal is not molten when you
tip it over.
So here's our slag for the borax, and then I knocked off the matte. So this kind
of looked like, there's the layer of matte at the bottom of the cone and then
here's the little lead button. So we'll go get the lead button weighted, see how much
it weighs. But anytime you have matte in the smelt, that's really not a very good
sign. So there's probably some precious metals, especially silver, that get
absorbed into the matte and you really really don't want to matte, you really
wanted to have just a metal collector button whether that's lead or copper or
just gold and silver and slag and no matte. So that's what we're trying to get
away from. So here's our first little lead button from the borax.
It weighs 26 grams. So we ended up losing quite a bit of weight and what happened
was there's some free sulfur that bonded with the lead and made lead sulfide that
went into that matte, and this is the remaining metal that there wasn't enough
sulfur to absorb it all, so this is what's left. But like I say anytime you
get a matte, especially with lead or copper, you end up losing some precious metals in
your matte so we want to get away from matte. I've made a cupel here out of
Portland cement and I'm going to put lead frill from the borax test in the
center, get it hot with the torch and oxidize it.The lead oxide is going to go
into the cement and the cupel and any precious metals are going to be left as
a little tiny bead there in the center. And I've got another video showing how
to cupel a little bit more detail so I'll put that in the upper right hand
corner of the screen here so you can check it out.
Here's some shots that cupelling process sped up about six times and as
lead melts it oxidizes and oxidized lead runs into cupel and you're left with a
precious metal bead containing all the gold and silver that was in the sample
Alright here's our first little tiny pearl from cupelling our borax
experiment. And so I'm going to try and get this on the scale here, we'll see how much
it weighs. So there's are borax pearl, it weighs 0.0405 grams,
probably 0.04 grams. So there's not much there, but we did recover some so as
we can get these other pearls and get them weighed we can compare how much
recovery we got from our different flux recipes. So we just poured our
borax charge and in there now it's our Chapman flux and sulfide charge, it's
starting to heat up.
So there's the Chapman flux charge, it started to boil and bubble a little bit,
so the reactions are taking place. And it's coming up in temperature so
I'll let that thing quiet down a little bit and then we'll pour it here in a minute.
here's our matte bead from the Chapman flux, here's our lead button, and then here's
the matte portion.
So let's take this lead button over and get it weighed. So our champions flux button weighs 31.5
grams, a little bit more than the borax but still nowhere near our 50
grams you wanted. Here's our matte from the borax and ended up weighing 80 grams
and here's our matte from the Chapman flux sulfides
and this ended up weighing 65 grams so Chapman's flux did oxidize some of the
sulfides, we got less matte and also increased the size for a lead button a
little bit, I think about 10 grams or so. So the Chapmans flux is a little bit
better than just straight borax, but we still want to get away from this matte
and we'll see if the last two and do that. So here's our frill from the
Chapman's flux with the sulfides. And it's a little bigger I think, so let's
get it on the scale here.
Zero it out.
0.06...
so 0.06 grams, so it's actually 50% more then just the borax. So we've increased
our recovery there by oxidizing some of those sulfides, get more lead in the
button, and reducing the amount of matte in the smelt. All right so we got our 75 grams of
sulfides here roasting just cast-iron pan right over our furnace and you don't
want to get them so hot that they start to turn red and glow you just want to
oxidize them and they'll end up turning kind of black color and then when they
cool down they'll be a red color, kinda like rust. So that's how I'm roasting our
sulfides for the number-3 sample of the Chapman's flux. Once the sulfides reach about
800 to a 1000 degrees Fahrenheit, they start to react with the
oxygen in the atmosphere and drive the sulfur off as SO2 and convert the
sulfides to oxides. And here you can see a little bit of that blue smoke coming
off that's the SO2 that's being driven off the sulfides, and once they stop
smoking then the reaction is complete. Here's our roasted sulfides and they
didn't and they're being as red as I thought they they would be but they're
they're all oxidized. We would replace the sulfur with oxygen and drove off the
sulfur is SO2 but I actually reweighed these after they've cooled down and the
only way about 55 grams now instead of the 75 grams we started with, so we
drove off quite a bit of sulfur there and reduced the overall weight. Here's
our tests with the Chapman flux and the roasted sulfides, and you can see here's
our lead button it's a glassy slag all the way down onto
the lead there. And then down here you can see there's no there's no matte,
so by roasting the sulfides we oxidize them all got rid all that sulfur and now
we're left with the clean metal button and glassy slag just like we needed. So
we'll get this thing weighed and see how if we if we still have our 50 grams. So
here's our Chapman's flux and roasted sulfides. We ended up with 47.4
grams, and we lost a little bit of lead but that is to be expected because
there's some oxidizing agent in the Chapman flux so for two and a half grams
lost that's not a big deal. We got rid of our matte and now all of our precious
metals should be in this little button now. Here's the final stage of the
cupelling process and at the very end right is the lead button gets small
enough and completely oxidizes the remaining precious metals actually blink
over to a precious metal prill. In this video it's kind of subtle but it happens
right now. And there is our bead from the roasted sulfides and Chapman's flux. So
here's a little bead from the Chapmans flux and the roasted sulfides and I can
tell right now it's it's already bigger than the last ones
so let's get it wait here and see how much more we got. Well dang, 0.15 grams! So
it's it's almost it's almost three times three times more than those other ones.
And so that goes to show you when when you eliminate the matte and recover all
your lead, see if I can get it focused here, you can you can recover quite a bit
more gold and silver, the silver goes in there as well.
So here's a piece of iron it's an iron pipe that I'm going to add into the
crucible here for our last experiment. Iron is a fairly reactive metal and when
you add metallic iron in with sulfides of other base metals such as copper or
lead that iron robs the sulfur from those other base metals and reduces them
to metallic copper or lead and creates an iron sulfide. Now the iron sulfide is
then soluble in that basic slag we're making, so at the end you end up with two
products you end up with a metal button at the bottom of the cone mold and then
a slag phase on top and all the matte is absorbed into the slag.
And here you can see the bottom of that iron pipe was heavily eaten by the
charge, and so any base metals were reduced to metallic form and any extra
sulphur attached to any of the iron sulphides were completely used out
formed FeS which is insoluble in our basic slag.
Well we have a little bit of a mess with this last one, this is iron nail one. And
you can see the slag is a little bit different than the other one just like a
matted kind of stony colored looking thing versus this is some of the other
slag from our other runs where it's real glassy and vitreous and acidic. So
this is this here is an acidic slag and this is a basic slag and the reason why
we had to make it basic was because the basic slag will actually absorb the iron
sulfide that we create by adding the iron, which pulls the sulfur off all the
other the base metals in there, reduces them the base metals, and they'll end up
going into our lead button. But the problem is I got too excited I break it
open well it was still a little bit too hot and the lead has, even still hot, the
lead has fused to the bottom of the slag so I'm gonna clean this up as best I can
to get as much lead as I can once it cools down and get it weighed. I expect
that I won't be able to get it all but hopefully I can get you know 90% of it
and we can that we can see what we got there.
So I'm actually getting it cleaned up pretty good but I wanted to show you
here's a good spot to show you aware that the lead button comes right up to
the slag, there's no matte in there at all and so we we've got rid of all
the all the sulfides they got dissolved into the basic slag we made and it's
just metal and and slag so that's a good sign.
But I am I am able to get quite a bit of this metal off of here so I think we can
get 90 or 95 percent recovery of this this lead here. Alright so I was able to
recover most of the lead almost all the lead from the soda slag, that basic slag
and total weight is 46 grams almost. So we got it back almost all our lead and
so now let's cupel and see if we can get as large a button as we did with
our with our Chapman's flux and roasted sulfides. And here is our last one, the
soda iron method. And we recovered a significant amount more gold as well
with no matte so it's a 0.13 grams. I think the most recovered was with
roasted sulfides which was 0.15 grams and so that's pretty cool. Let me get all
the beads lined out here we can take a look at their sizes.
All right and there we have it. The one on the left is the borax with sulfides,
the second one is the Chapmans flux with sulfides, the third and largest one is
the Chapman flux with roasted sulfides so we oxidize them all, and the one on the
far right is the soda iron method where we didn't roast them but we didn't end
up with a matte. So I think what we've proved today is that matte is bad and if
you can oxidize the material or absorb the sulfide as an iron sulphide and
remove the matte is the way to go. We recovered almost three times more gold
when we didn't have matte then when we did. So hope you guys enjoyed the video
thanks for watching and we'll see you next one.