Hey guys my name is Jason with Mount Baker Mining and Metals and I've been
getting back into some of the experiments I've been doing with
smelting black sand and sulphide concentrates off the shaker table and
this video series I'm going to be doing some experiments with determining what
type of collector metal works the best for gold recovery. So we're going to do
several different smelts with several different collector metals and I'm going
to get the slag assayed to determine how much gold and silver we lost and I'm
also going to assay the head ore that we use, the concentrates off the shaker
table, so we'll know how much gold we put in. And by finding out how much gold we
had to start with and how much gold we lost we should be able to find out the
percent recovery. So first just real quick let's go over the furnace. This is
just a propane bottle, there's a regulator I bought off eBay, and this is
a little homemade furnace that I made myself, cost about 100 bucks. This is a
two-inch kaolwool that I've just banded on with some tie wire and some banding.
And underneath it's an 8 inch piece of stainless steel pipe, there's two, there's
one, and there's another one on the other side. Tangential inlets for the propane. A
cap plate and then a three inch square tube for the exhaust. The other reason I
really like this furnace style is the fire bricks are really cheap and I've
been experimenting with a lot of different flux recipes and sometimes
they boil over, and so you have your your fire brick hearth that gets all the slag
that comes out, boils over the top and lands on your fire brick hearth. This
thing's about ten dollars worth of fire brick, so when it gets so bad that I
can't use it anymore I throw the fire bricks out. In this furnace I've done
about 30 charges now. But that's really in a nutshell the furnace and the setup
it gets way over 2,000 degrees Fahrenheit, copper melts no problem in it,
it's a great smelting setup, the liner stainless steel is easy to replace, the hearth
is easy to replace if you start spilling stuff and you know hot goo all over the
place it's not that big of a deal. Here's the material we're going to be
experimenting with. This is some high-grade concentrates off the shaker
table. On all of the charges I'm going to be adding metallic iron in the form of I
think I'm going to use a piece of steel flat bar, and I stick it right down the
top of the furnace right into the crucible and that way the iron will
reduce any of the other metallic components, lead, copper, into metallic
form and they will precipitate hopefully down through the slag and collect in the
bottom as a metallic metal either in the collector metal that we use or as a
button if we don't use any collector metal. Okay so we've added our three
components to our flux here, we've got 100 grams of number one shaker table
concentrates in the bottom, I've added 150 grams soda ash, 30 grams of silica,
and 30 grams of borax. I'm going to take it, put a lid on this shake it up mix it
up real good. And we keep the flux really basic because the basic flux will absorb
the FeS, the iron sulfide that we create by adding the iron the metallic iron to
this material as it fluxes, so when if there's any galena in here the PbS will
convert to FeS and the result will be metallic lead that will then fall down
to the bottom. Okay we just put our charge in we've got a piece of rebar
sticking out the top of furnace. The crucible down there it's just
starting to glow a dull red so I just added the charge. And I'll let that, it'll
probably take about 10 minutes to fully melt, and then I'm going to fuse it for
maybe another 10 or 15 minutes. Okay so we've got our stuff off temperature, it's
not forming a bunch of bubbles, it's all nice and quiet now, so we're going to
go ahead and pour it into our preheated cone mold.
I'm going to add my copper to our next experiment. There's our next round.
Here's our cooled down slag and we're going to knock that out of the cone mold and
we'll see what ended up being reduced on the bottom as far as metallics. Okay so I
just take my cone mold, I turn it over in my metallic bin here, give it some taps
with a hammer and usually the slag comes out, yeah there it is.
So there's our slag, it's probably still hot, but this right here looks like our...
yep, so there's our metallic button. And again this was just adding iron to our
basic flux and our 100 grams of stuff off the shaker table and we ended up
with a little metallic button. So we reduced the less reactive metals than
iron by putting metallic iron into the mix. So here's our little metallic button
from our first experiment and it's still, it's not quite cleaned up there's a
little bit of slag on there, but it looks like from a hundred grams we ended up
with an 18 gram button in the bottom so that's actually pretty good. All right so
this is our first sample of the collector metal, we used copper. Oh it
came out as a nice piece, so there's our collector metal that all came down the
bottom. We added a hundred grams of copper, high surface area copper. You can
see on the slag it's fantastic separation from the metallic section
from the slag, there's no beads of copper or anything in the slag left there. The
slag is nice and hard and competent. The metallic section is flat on the top.
That's just about as perfect as it gets. So I wanted to point out one more thing,
I broke our slag apart and you can see there's no matte at all, there's no matte
layer. So the basic slag did its job, it absorbed all the iron sulphide that we
made, and it really came out, just, I mean that was
a beautiful pour, that really worked very nicely. Alright for this next
experiment I'm going to use silver as a collector metal instead of copper.
Alright just poured our first silver test, you can see there's our silver
collector metal at the bottom of the cone. Right here's our silver button
collector metal, we ended up with 108 grams. So we started with 94 so that's 14
grams of additional metal was collected by the silver collector.
Okay we just knocked our lead charge out of there, and it might be hard to see but
there's a lead button at the bottom of this one. So I had about one and a half
kilograms the shaker table concentrates that I used the same slag, or the same
flux recipe for all of these samples and the only thing I changed was the
collector metal. But I took out two separate samples of the shaker table
cons, so we're going to send these off for assay. That will tell us how much
gold we have in our sample that we started with. The first test I did, and
all these are duplicates of each other, the first test I did two samples exactly
the same of no collector metal. So I used my flux recipe and added iron to reduce all
the metallics above iron on the reactivity chart. But we ended up with
two little buttons with no collector metal used. The second one we did I took
high surface area copper and mixed it in with the entire charge, 100 grams of
copper. The second one we did was we just added 100 grams of copper right to the
bottom of the charge, we put it right in the bottom the crucible. The next one we
did was we use silver, used three ounces of silver ended up, being about
94 grams of pure silver, and I use the button twice and put it right in the
bottom of the crucible. The last one was, I used lead, and I put 100 grams of lead
in the bottom of the crucible, put the charge right on top and we use lead as a
collector. So there are all of our different samples, I'm going to send the
slag of all of them off for assay and the slag will tell us how much gold and
silver is left over after the collector metal is used. I've really gone back and
forth with myself about if I'm going to crush up the slag and see if there's any
metallic beads left over in the slag and if there is should I get those out
because it will contaminate the assay. And I am NOT going to crush up the slag,
I'm going to send it as is. The reason we're doing all this is because I want
to know the best way to go about collecting the most
precious metals the easiest possible way. If you need a high surface area
collector metal that is throughout the charge that trickles down through, that's
okay, we need to find that out. If you can just put a slab of metal in the bottom
and have it collect through contact with the convection going on in the crucible,
if that works? Great! If silver works better than copper we'll know that, if
lead works better than copper, we'll know that. So this is a first pass trial run
to figure out how much gold and precious metals we can recover through smelting
without roasting and by using iron as a reducer and then we can assess which
collector metal does the best job.