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. At 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 90 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 little 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 called 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 of carbon, spiegel, ferro-man- 

 ganese, tungsten, ferro-silicon, vanadium, 

 or 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. 



153 



