Refractory Clay for Crucibles & Furnaces

I have been reading an old text book on assaying and refining of gold & silver ores and have decided to give smelting a go to recover the almost microscopic gold I am getting from ore left on old mullock dumps.
I have a small wind forge that could be easily converted to an enclosed furnace to smelt the concentrates in a crucible then cupel the resulting dore button.
I am looking for advice on a source of refactory clay and the steps involved in making furnaces / crucibles from anyone who has attempted this or something similar such as a pizza oven or melting gold for jewelery making.
My wind forge runs on charcoal for fuel at the moment. I have a constant supply of charcoal from our slow combustion heater.

G'day jethro, this is an interesting post and I will be following.
Hope you get the answers you are looking for.

Maybe check out youtube for some answers?. Cheers Nick.

jethro said:

I have been reading an old text book on assaying and refining of gold & silver ores and have decided to give smelting a go to recover the almost microscopic gold I am getting from ore left on old mullock dumps.
I have a small wind forge that could be easily converted to an enclosed furnace to smelt the concentrates in a crucible then cupel the resulting dore button.
I am looking for advice on a source of refactory clay and the steps involved in making furnaces / crucibles from anyone who has attempted this or something similar such as a pizza oven or melting gold for jewelery making.
My wind forge runs on charcoal for fuel at the moment. I have a constant supply of charcoal from our slow combustion heater.

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Certainly cant promise anything but can atleast ask the question at work...the powerstation i work at uses refractory to line parts of the burner ducts in the boiler and being in the middle of an outage is large numbers of bags around at the moment, i MAY be able to get some but will keep u posted.

Hey jethro, hope you fine some refractory clay. I'm down in Launceston, Tasmania and I couldn't find any close by so i couldn't make my crucible and the idea just got forgotten. Best of luck.

Certainly cant promise anything but can atleast ask the question at work...the powerstation i work at uses refractory to line parts of the burner ducts in the boiler and being in the middle of an outage is large numbers of bags around at the moment, i MAY be able to get some but will keep u posted.

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Hey Y4k even if you can find out the name of the product & supplier that would be handy as cruicibles dont last forever & Iwas planning on making a mould so I can knock out a few and have a supply on hand. thanks in advance

jethro

This may not be what you are after, but interesting none the less, I did a quick Google search of "Small furnace" and it provided a series of different projects in this area. I have also seen in the past that I think just used plaster instead of clay, not really a long lasting option, but one to play with.

Rob.

Jethro you can buy crucibles on ebay dirt cheep! cheers John.

Crucibles are not so much of a problem but I need to make a domed roof to fit the top of my forge so that I can keep the heat in & get the crucible hot enough to melt the ore & fluxes.
Another thing I need to source is an assayers conicle mold to pour the molten charge into to allow the heavy metals to concentrate in the point of the cone. I have seen these made out of graphite, for sale on ebay but are very pricey to get here from the US.

Just use bricks, if you need to line it get a bag of brickies clay from Bunning's. You can also use the clay mixed 50/50 with very finely crushed fire bricks to make your crucibles. cheers John.

cant you use 50% cement and 50% plaster?

Just come off 3 weeks of nightshift so have a few days to try and get my 'normal' life back together before im back on days but have sent a message to the refractory guys at work and just awaiting a reply...just touching base so u know i havent forgotten lol

Having some trouble getting hold of the guy that might be able to help in regards to acquiring some bags so still unsure who supplies it...but did some digging found a few bags and can tell u the brand is Vesuvius. As i say i know very little about it so unsure if it needs anything added to it or whether its similar to ur quickset cement but will continue trying to contact him (or anyone else who may know)
y4k

Thanks for the effort mate, much appreciated

Might Help.
.
.
http://www.i3net.com.au/admin/app/w.../pdf/51d671d8-bbfc-44ec-a568-2b14ca07ddc9.pdf

Years back I have build and used small charcoal furnace for melting aluminium and brass. It worked really good. For formula for refractory mix
search for "2 bucks crucible furnace" .
Karl

i have started to make my own furnace the cheap way using cement - i will be using charcoal to heat it up

i currently use a mapp torch to make my silver bars

Hey tathra thanks for the link I will try & email them and see if they are interested in small one off lots.
And Karl I will check that one out as well.
John I think you are on the right track as I have come across a product made by boral that is called builders clay that is vertually the same chemical composition as old mate on youtube uses for his crucibles.

Hey there Jethro,
I used to work in a gold refinery (Only left a couple of months ago to move state), I could probably link you to a couple of sites for crucibles. However it depends on the size of the bars you are pouring, and the type of furnace and fluxes you are using - and whether they can supply single crucibles etc..

And If you are in the greater Melbourne region I could probably hook you up with a link to a guy that has been contracting with the company I worked with. He could do anything from selling you crucibles, to building a furnace, to melting it for you, or if you are really nice he might just give you some great advice. he has been in the industry for 30 odd years so he knows his way around.

P.s I know its my first post, so take the info as you will.. Just sharing what I know and trying to be of help

P.S.S - if you look for "How to make a coffee can forge" on youtube, there are a couple of good lips and how too's - and materials they use instead of cement (perlite) for the inside of the furnace.

I'm confused????? Do you want to smelt and refine or just heat it up to a button.

From what I can tell from the original post is that he wants to melt all of his flour gold into one "dore" bar (button) using flux to clean it up and get rid of any dirt and any other non-precious material.

then he wants to cupel said dore button... I'm not overly sure why he wants to do this, but most likely to raise the purity, but it probably wont raise the purity altogether that much. that's what you may think he means by refining.

or at least thats what I think is happening