It’s time again: The shaft furnace is fired. All of us get together like everytime to worship this miracle made of fire. Well, not everyone is present yet. In the morning some went to another experiment nearby. It investigates the use and efficiency of roman hand mills for grain (for further information [only in german] click here). In the meanwhile the remaining people heated up the furnace, so we are ready to start as soon as they are back.
With the whole crew the ore was attacked. The long pre-heating of the furnace seemed to pay off. Several times more than 1500 °C were reached and held over several minutes. But we just want to produce copper and not iron, so we had to restrain ourselves and tried to hold the temperature at around 1460 °C.
In the evening we relaxed with star gazing and discussions about Mars and subduction zones. Some of us merely did found to an end but sooner or later fatigue overcame all of us.
Some important terms one might should know:
Slag cake: final product of the smelting procedure in the shaft furnace, in which the molten ore was separated into is different parts.
Matte: copper rich part of the slag cake, intimately mixed with charcoal.
Slag: The silica- and iron rich part of the slag cake, waste product.
