questions on melting flour gold

[cwear]

Hello
I am working with flour gold,trying to melt it into bars. I am putting the gold in the crucible mixing it with 3 parts borax and 1 part soda ash. Preheating oven to 1900 and cooking for aprox 1 hr at 2100-2150 degrees. Pour into a cast iron mold. After it cools and we remove it from the mold the gold did not sink to the bottom it is swirled throughout the glass. What are we doing wrong? ??

 

[Mackaydon]

cwear: Welcome to Treasure Net !!
Here's another onliner's solution to your apparent situation:

Flour gold is smelted in a Vcella Model L pot furnace using a crucible made of graphite along with a "flux" (a mix of Borax, silica sand, soda ash and sodium nitrate) that floats on top of the metal and absorbs most of the non-gold impurities. Once the gold and impurities are molten it is poured into a mold and cooled. After the smelted product has cooled the impurites form into a glass-like substance that can be chipped away from the gold dore. It is then remelted and poured into another mold or cuppola to produce a cast bar or "button" (gold dore). The resulting gold dore bar or button is nearly pure gold along with minor amounts of other metals.

It takes one more step to produce .995-.999 "pure" gold bullion. The next step would be soaking the gold dore in nitric acid to disolve the silver and platinum group metals. Gold is the only metal not affected by nitric acid. Nitric acid has become difficult to obtain and is very dangerous to work with, therefore we do not take this final step in our processing.
Hope that helps,
Don...

 

[cwear]

Don
Out gold is still suspended in flakes throughout the glass. There is no solid piece of gold. When u break the glass the flakes are mixed throughout the glass
Thanks for your help.

 

[truckinbutch]

The cast iron mold could be chilling your pour too rapidly . Are you preheating the mold prior to pouring ?

 

[cwear]

No we haven't been I just read that last night. How hot should it be?

 

[truckinbutch]

No we haven't been I just read that last night. How hot should it be?

As hot as possible short of the melting point of cast . Gives the puddle more time to settle and segregate .

 

[cwear]

Does it sound like we are doing everything else right? Have been advised to put gold in crucible in first then mixture of borax and soda ash on top without mixing is that a good idea? Thx for your help

 

[truckinbutch]

I'll leave the fluxing technique question to folks here that are more experienced in refining gold .
Don't want to give you bad advice .

 

[niffler]

I was trained and have worked as a goldsmith and silversmith, and worked at a foundry at Idaho State University. It sounds to me like the gold is trapped in he flux. When a metal melts it tends to form a ball or button shape. My opinion is that before pouring into the mold, you should stir up the contents of your crucible with a carbon rod. When the melted gold balls that are in the flux touch each other, they will become bigger balls and eventually be heavy enough to pool at the bottom of the crucible. Also, possibly you could put the gold into the crucible and then cap it off by putting the flux on top instead of mixing the gold with the flux. Carbon rods are used in the welding field to gouge metal, sort of like a cutting torch without the plasma. If you go to a welding supplies store, you can get a carbon rod cheaply. Just be sure to peel off the copper foil on the outside of the rod before using it, or the copper will melt into your gold. I hope this helps, and I'm interested to hear how your gold bar making works out. Good luck, Niffler.

 

[cwear]

Would I pull out the crucible and stir it then pour into the mold or stir and heat some more

 

[niffler]

Cwear, I would heat it until the borax fused into sticky glass, then quickly stir it up...If it's still melted you could pour it out right away, or heat and stir some more. I have melted a lot of scrap gold and silver into ingots, and I always heat it with an oxy-acetalyne torch in a shallow crucible with the flux on top. The flour gold might fly out of the crucible from the force of the torches oxidizing flame though, so the furnace seems like a good idea. Good luck, Niffler.

 

[joesteele]

I have the same problem. Have you found a answer?

I have been trying to smelt black sand and have gotten to the point of casting the flux/gold/glass into a cast iron mold. it comes right out of the mold but it is obvious that the gold is still in suspension. has the carbon rod stir helped? extra heating?

Do you have the cone shaped mold? I don't yet, since I am still in the experimentation stage. Have you had any luck?