Non-Chemical MELTING help with Elec-Furnace and GRAPHIRE crucibles.

[ALPHABiT]

Hi again to all.
I bought an electric-furnace (2Kg - 1300W - 1150 °C) .
(an used one, i payed less then half)

I had 2 graphite furnace-crucibles with it. One of them still containing about 100gr of solidificated silver in it.

That was a great thing to TEST the furnace, i tought.

Ok I tried it, and it seems to work fine... BUT i encountered some problems i really will not want to see again when i'll start to melt gold in it!

Once liquified the silver, i used the accessory gave me to keep up the crucible and fall into a inox container.

1st problem: really hard to manage an incandescent crucible with that... Not a problem to keep the crucible out, but really hard to move it to empty down (see 1st photo pls, i keep it up from the larger part of the cilinder, but very instable!).

2nd problem: not all the silver contained came down! A third part resisted in the bottom part of the crucible. (and i understood why l8er...)

3rd problem: i think guy who used this before, never used BORAX in the crucible, so parts of silver are around of the graphite (into).

4th problem: i removed mechanically last part of the bottom crucible once cooled. And what i got was a mix (i think) of silver and graphite powder.

Now... My questions to you, erudites


a) Will i experience same problem with gold too ? I mean... If i use a lot of borax in those crucibles, will i drop "all" gold contained in "uncontaminatd" mode easly ?

b) DO yuo think i have to buy new crucibles to melt gold, or can i clean those to use again ? And if i can, simply remove it from internal surface ?

c) Does exist any way to clean that silver from graphite ?

d) What can i use to manage easily incandescent crucibles ? Another accessory i dont know ?

Thanx 4 help, guyz.

 

[ALPHABiT]

 

[lazersteve]

Alpha,

Sorry for the delayed response.

Nitric should separate the silver form the graphite.

Melting with a little borax may also do the trick.

Steve

 

[Harold_V]

When melting pure metals, a dedicated crucible (melting dish) should be used. The slightest trace of other elements undermines the refining effort, and it's virtually impossible to rid a used crucible of contaminants.

I have regularly spoken against the melting of gold in furnaces. It's far easier to torch melt, and you won't have any of the problems you've mentioned. I would have encouraged you to forego the electric furnace and get set up with an oxy/acetylene torch, or even natural gas and oxygen.

Melt your metals in clay melting dishes, which will provide far better service than graphite crucibles. Graphite crucibles really don't like being fluxed, and if you flux freely, you'll include the flux in your ingots. You can avoid all of those problems by using a clay dish, properly seasoned and flux coated.

I may not understand your objective. If I am walking the wrong path, please provide more information.

Harold

 

[ALPHABiT]

Hi Harold,
i understand what you mean. And i think to understand because an elec-furnace usage hurt you a bit too. I also saw the way Ceramic or Graphite answer on work... And belive me, i start to hate graphite!

But i started this project considering to work safe and simpler.
I'm noob at all to this. Using an oxy/acetylene torch means a bit of risk, and much more handless i have not, right now. I saw some videos about torch usage, and every time i see them, i think i cant do that (right now). Of course i'm seriously considered to make some practice about it. Starting using the torch to put borax on ingot molders and make them hotter for the casting part.

Other thing i considered, maybe wrongly, is that it's easier use torch when you have few grams of gold, but really harder when you have to melt 1Kg or more per time.

Procedure i'm trying to setup is:

- Collect solid gold 9/12/14/18/22 Kt
- Molding in a ingot
- Electrolisys with ingot
- Precipitate powder of 999
- Make new pure 999 ingots melting powder and casting.
- Stamp ingots (not sure yet)