National Geographic : 1917 Aug
Photograph from Carnegie Steel Company GIANT BLAST FURNACE, SHOWING A PORTION OF THE APPARATUS WHICH SUPPLIES THE FORCED DRAFT The modern blast furnace is a tremendous and spectacular institution. n~t the top it takes in coke and ore and limestones and turns loose two streams of molten material at the base. It is a large, circular, silo-shaped affair, some go feet high, kept going day and night, Sunday and Christmas alike, year in and year out, when it does not give way under the strain. preceding charge. Then a itte train rolls up before the battery, and an elec tric crane dumps box after box of scrap metal from the cars into the furnaces. Off some distance is a great steel tank lined with fire-brick and full of liquid pig metal. This big tanK is callea a mixer, and in it hundreds of tons of the flowing, glowing iron are mixed. Thus homogen ized, the contents of the mixer are drawn off into a giant ladle, like water from a spigot, carried across to the furnace by an electric crane and poured into it. Every now and then, as the process goes on, a laborer puts a shovelful of lime stone into the mixture to coax off its affinities that remained behind when the ore was under conversion into pig metal. When the scrap has melted and the contents of the cauldron are cooked enough; when the impurities have been driven out and tolled away, the fiery broth is "seasoned," as it were, with the proper amount o. caroon, spiege., .erro-man ganese, tungsten, ferro-silicon, vanadium, ,r whatever is necessary to give the de sired character to the resulting steel. Then comes the tapping of the fur nace. An electric crane lifts a great ladle into position, a workman jams a crowbar through a clay-plugged hole at the base, and out flows the frenzied stream into the ladle. The slag rises to the top like oil on water and overflows, congealing on the outside of the ladle. Then the big crane picks up the ladle, swings it over to the pouring platform, where it in its turn is tapped and its purified fluid run off into molds. 'Great care has to be taken in handling these ladles, for the presence of a few drops of moisture when the hot metal is poured into it might cause an explosion and loss of life. Just before they receive the molten metal the ladles are heated nearly white hot in order that the steel or iron may not chill in them.