Another Close-up View
As in the blast furnace, limestone is added as flux to make liquid and dispose of sand, dirt, scale, etc., which are detrimental. The liquid slag formed from union of limestone with these impurities floats upon the molten iron in the cupola hearth, as it is less than half as heavy as the iron itself. It flows almost continuously from a higher hole called the “slag hole,” in the rear of the furnace and just beneath the tuyères. The slag has little value except as material for filling purposes, etc. So-called “slag wool” can be made by blowing air through it. Sometimes the blast from the cupola blows it in such a way that this pure white “wool” is formed and blows out of the slag hole of the cupola. About Christmas time some of the workmen take quantities of it home for decoration and for fireproof whiskers for “Santa Claus.”
These operations go on continuously throughout the day, each cupola making the particular grade of cast iron or “semi-steel” which is best adapted to the particular castings to be poured, size, shape and purpose of
Determining Carbon by Direct Combustion
In an electric furnace with pure oxygen passing over them, the drillings burn as would splinters of wood. From the gas given off the total carbon is determined with great accuracy.
Weighing Pig Iron for the Cupola
From three to six varieties of pig iron are used in each charge.
The Receiver Building
Here pig irons of different compositions are separately kept in numbered and labeled bins. The magnet which is used for unloading and handling the iron may be seen. The grab bucket for sand is at the right.
