SECTION OF BLAST FURNACE SHOWING FILLING ARRANGEMENT, BINS AND ORE BRIDGE
And now a shout and the strong red glow throughout the cast house tell us that the tap hole is open and the iron is running down the main channel of the sand bed. Past the plugged entrances to the lateral branches runs the molten iron stream to the end of the cast house nearly one hundred feet distant where it divides, filling the laterals on each side and from them running into many open molds arranged like the teeth of a comb. Each of these molds is about five feet long. They form the “pigs,” and the laterals what are known as “sows.” As each lateral and its molds fill, the lateral ahead of it is opened and the process repeated, laterals and pigs filling up simultaneously on opposite sides of the main channel till the whole cast house floor is filled nearly up to the furnace with the red smoking metal.
Sand Cast Pig Iron
There are few sights more glorious than the cast house with bed just filling with metal, and especially is it so at night. The strong yellow-red light of the flaming metal issuing from the furnace and the intense glow of that already in the bed illuminates everything in and about the building. But already, before the furnace is empty, the workmen are spraying with water the earliest cast pigs. Covering them with a light layer of sand they venture upon them with thick-soled shoes and break the “pigs” from the “sows” with sledge hammers.
This is the old-fashioned “sand cast” pig iron. After remelting in the cupola furnaces of neighboring towns and casting into stove parts or other forms it is known as “cast iron”; through “puddling” in reverberatory or special furnaces it becomes “wrought iron”; after decarbonizing treatment in steel furnaces of various design it is changed into the wonderful material called “steel.”
Pig iron is thus the intermediate or semi-raw material from which practically all of our various iron and steel products are made and the transition product through which they pass.
Machine Cast Pig Iron