Slag

In ironmaking, the furnace produced a molten waste called slag, which workers periodically drained through the cinder notch at the base of the furnace and later sold for road building and for making concrete and mineral wool. Because the sealed, pressurized furnace ran continuously, coke ash and impurities in the ore could not be removed by hand, so a flux was added to combine with those impurities into a liquid compound; the principal slagmaking constituents were lime, silica, alumina, and magnesia. The process produced much more slag than iron, requiring workers to flush slag more often than they cast iron. At Sloss, slag was sent either to slag pits, where it was sprayed with water, cooled slowly, and loaded by electric shovel into railroad cars for the slag plant, or to a slag granulator, where rapid cooling by water and steam and crushing by drum-shaped granulators created expanded slag for structural concrete, floor and acoustical tiles, and wall insulation. At the slag plant, slag was crushed and sized, with some sent to an adjacent concrete plant and the rest sold to paving contractors for road construction. Each furnace had a six-man crew led by the stove tender, who supervised casting iron, flushing slag, changing stoves, and adjusting the wind, with a furnace keeper in charge of the iron notch, a fallman responsible for the cinder notch, and three laborers under him. Before the Civil Rights Act of 1965, these jobs followed an openly acknowledged but unwritten racial division in which the stove tender was always white and the keeper, fallman, and laborers were always black, and black workers were barred from bidding on white jobs.

Birmingham, Alabama · United States