At the Nucor-Yamato Steel Co. plant outside Blytheville, Ark., small mountains of rusted scrap metal rise across a stretch of Mississippi River floodplain. Most of the material, sorted by size and type, is completely unrecognizable. Some piles contain thin sheet metal. Some have pieces of buildings or machines, and in spots you see lengths of pipe. The finest scrap, called shredded scrap or “frag,” looks like metal garden mulch or tea.
Several heaps hold discarded tails from brand-new wide-flange beams—generically called I-beams, though there are several different shapes. This is the basic unit of heavy steel construction for buildings. The 850-acre Nucor-Yamato plant, with its two gargantuan, parallel sheds, makes about 2.2 million tons of structural beams a year. In about four hours' time, 125 tons of the scrap in the yard here will be recycled into steel beams.
Inside the plant's hazy, Piranesian depths, 860 employees work 12-hour shifts—four days on, four days off. They tend exploding furnaces as big as brownstones, monster vats of molten steel, and more than a soccer field's worth of mills and presses that pound metal into shape. Out of the roaring machinery, ranks of near-perfect beams sidle off the line, glowing orange and gradually turning a cool gray.
Steel, the miracle metal of the industrial age, is iron alloyed to any of various elements to suit the desired purpose. That could be pipes, tubes, plates, rebar, bed frames, saucepans, or ship hulls—or, at the Nucor-Yamato plant, structural beams for building frames.
Steelmaking originally depended solely on the mining of iron ore. Yet because steel can be melted and remade almost infinitely, American industry recycles more steel than it does anything else. About 95 percent of the content in Nucor-Yamato's beams is metal that once existed as something else.
The Scrap Yard
Usually, in Blytheville, making steel begins by unloading scrap on the river, though some scrap arrives by truck or train. Barges pull up to the plant's port from up and down the Mississippi and Ohio rivers. Loads vary, but a single barge may hold up to 1,400 tons of shredded scrap. It takes two hours to empty—using a crane-like mechanical claw, known as a grappler, and, sometimes, an enormous magnet—into a fleet of Komatsu hauling trucks with wheels 7 feet high.
In the scrap yard, another grappler is at work. Equipped with a scale, it weighs the scrap—and, sometimes, chunks of processed iron known as pig iron—while loading the piles into an armored vessel called a scrap charging bucket, which stands nearly 20 feet high and looks like a gigantic hand grenade. Nearly everything about the plant is audaciously large.
About 4,000 cubic feet of scrap fit in the bucket. It sits on wheels and, when full, is rolled into the plant and raised on an overhead crane affixed inside the plant's soaring roof structure. Traveling upward, it floats above the factory's maze of moving parts until its hinged clamshell bottom hangs over the lid of the furnace.
The Electric Arc Furnace
Nucor-Yamato relies on a method of steelmaking called electric arc furnace, or EAF technology. The electric arc furnace proper is a big, dirty cauldron of fire. Its inner lining of refractory brick protects the rest of the furnace from melting in the heat.
When the furnace's roof pivots open, the charging bucket's hinged bottom doors fall open. The scrap crashes into the glowing orange void with a thunderous impact, and flames erupt above the furnace. The roof swings closed.
Three white-hot carbon electrodes, each two feet in diameter, descend through openings at the roof's center and strike an arc of electricity into the scrap. A storm begins: Clouds of fire and sparks burst out of gaps in the furnace roof as the electrodes subdue the steel into a blindingly hot porridge. A safe distance away, in a windowed, heat-shielded control room or “pulpit,” a worker known as a first helper watches several computer screens that report the status of the melting batch, known as a heat. The first helper tracks the temperature as it rises to about 3,000 degrees Fahrenheit. He also calculates carbon levels, which fall as oxygen levels rise. Higher carbon content makes steel more brittle. He waits for the carbon to reach a desired low of about 0.1 percent of the molten steel.
As the steel cooks, its foamy by-product, slag (consisting largely of lime), floats to the top and is skimmed off into a cone-shaped slag pot for processing into an aggregate for roadbeds. When the steel has melted, it is time for the “tap.” A slot opens at the furnace's underside to empty the liquid into a wheeled vessel beneath it, known as a ladle.