melting gold dust and flux with charcoal and air

[Professor]

I've searched the posts but can't find a reference that tells how to use charcoal and forced air alone to melt gold and borax. Ancient prospectors surely had a way. My experience was that it was too cold, borax didn't even melt. Should I have blown the charcoal from the up side downward?

 

[solar_plasma]

I've got something like this:

http://de.wikipedia.org/wiki/Esse_(Feuerstelle)#mediaviewer/File:Reise-Esse.jpg

I have still not tried it, but I would believe, if it would be combined with four fire-bricks around the place for the crucible, it should work. Something that makes a steel rod white glowing, should easily yield temperatures about 1200-1300°C in a crucible, too.

http://de.wikipedia.org/wiki/Glühen

 

[Justincase]

Open charcoal will not retain enough heat to get to the desired temperatures.
You will still need to make a furnace to trap as much energy as possible.
Charcoal furnaces are a lot of work,they need constant stoking and every time you add fuel you drop the temperature.
They died out for a reason,I still use a little to warm up my furnace slowly but then turn on the gas.

 

[goldsilverpro]

I just found this excellent blacksmith color vs temperature scale.

http://www.blksmth.com/heat_colors.htm