ALUMINUM,

the Magic Metal


by: Thomas Y. Canby

I

T IS 1942: A NAZI U-BOAT SURFACES IN FOGGY DARKNESS off a lonely Long Island beach and four invaders land stealthily. Armed with sophisticated explosives, the saboteurs seek to cripple America’s burgeoning air armada. Among their targets—aluminum smelters in New York and Tennessee. Their plan—destroy the cables that carry electricity for processing the alum-inum . Long before power can be restored, the molten metal will solidify in the furnaces so that only blasting can remove it, knocking out the smelters for months.


Before the enemy agents can strike, the FBI scoops them up. But the lesson is clear. The light, shiny metal that began its working life as kitchen pots and pans has now emerged as a sinew of industrial society.


Discovered a mere 150 years ago and manufactured commercially just half that long, aluminum today ranks behind only iron and steel among metals serving mankind. The key is incredible versatility.


The same filmy metal that makes our kitchen foil (last year we unrolled 20 billion square feet of it) serves as armor for Uncle Sam’s battlefield tanks. The stuff of lawn chairs and Little League baseball bats also forms the vitals of our air and space vehicles—most of their skeletons, their skins, even the rivets that bind them together.


Versatile? Spread less than an ounce of aluminum over a thin Mylar sheet and it keeps a sleeping camper snugly warm; spread just a few ounces over an asbestos suit and it keeps a fire fighter “cool.” Mix pulverized aluminum in a liquid medium and it forms a durable paint; reduce it to powder and it becomes rocket fuel and a high explosive. Look around. The magic metal dads trucks, trains, houses, skyscrapers. Look seaward. Aluminum ships in swelling squadrons cleave the waves , from trawlers to pleasure craft; five of the seven yachts fighting for the 1977 America’s Cup raced on aluminum hulls.


Glance overhead. A vast web of aluminum transmission cables feeds the nation’s vital electric power grids. Indeed, just as earlier ages of human development have taken their names from the distinctive material that nurtured them—Stone, Bronze, Iron—there are those who believe our era may be called the Aluminum Age. Cultural analyst Lewis Mumford observes that just as the industrial revolution transmuted “clumsy wooden machines into stronger and more accurate iron ones,” a task of today is “to translate heavy iron forms into lighter aluminum ones.”


Behind aluminum’s versatility lie properties so diverse they almost seem to belong to several different metals.


For example, in pure form aluminum is soft enough to whittle. Yet its alloys can possess the strength of steel, though only a third the weight. Thus when sculptor Alexander Calder designed his last mobile—a soaring creation 80 feet long—his choice of aluminum over steel slashed two tons from its weight. Aluminum also assures the masterpiece virtual immortality: The instant the metal is exposed to air its surface acquires a transparent film of “rust” that seals the interior against further corrosion.


Consider a few more of aluminum’ s useful properties. Farmers throughout the South and the Southwest, knowing that cows give more milk when cool, nail heat-reflecting aluminum roofs on their dairy barns. Homeowners cherish aluminum siding and gutters, whose durable surfaces can keep paintbrushes on the shelf 15 years or more. Food and beverage packagers revel in a metal so chemically stable that it doesn’t react with most foods.


Globe-girdling Strand Possible


No other metal so obligingly takes the myriad shapes that meet our everyday needs. You can roll aluminum and forge it, saw, slit, and shear it, and shape it by extruding—forcing it through a die of almost any shape, much as you squeeze toothpaste through a tube . By drawing aluminum, you can wind a wire so spiderweb thin that a strand weighing only a few hundred pounds could stretch around the world.


Cast in so many roles, aluminum naturally presents some paradoxes. Among them: The smelting process guzzles vast amounts of energy; a medium-size plant in Montana gulps nearly a third of all the electricity consumed in the state. Yet--- aluminum offers a shining hope for energy conservation. Once made, the metal can be recycled over and over for only a fraction of the energy used in making it originally. Also, by putting our overweight autos on a strict aluminum diet, we can drastically reduce their weight and thus their thirst for gasoline.


• Half of those beverage cans that glitter so malevolently in the litter along our own roadsides are aluminum, yet they help shape a new environmental ethic. Spurred by offers of cash for recycling, Americans last year returned an incredible six billion cans—one of every four aluminum cans manufactured.


• Scoop up a handful of soil in your backyard and you probably hold a fair amount of aluminum, for it forms a 12th of earth’s crust. Yet most of the richest ores are controlled by an association largely composed of Third World nations. U. S. policy-makers include aluminum among such sensitive strategic materials as oil and cobalt.


“Contrariness” Put Off Discovery


How could the most abundant metallic element on earth remain so long undiscovered? The answer is that this obliging metal is also extremely contrary. As early as the 1700’s European chemists realized an invisible metal lurked in certain soils they called clays. Later a particularly rich source was found in southern France, near the medieval town of Les Baux-—thus the name bauxite, as all similar ores are known.


 But unlike long-familiar copper or iron, aluminum does not occur naturally in any metallic form. It exists only in combination with other elements, primarily oxygen, with which it forms an extremely hard oxide known as alumina. When tinted by traces of other elements, alumina can take the form of gems such as rubies and sapphires.   The challenge of liberating this “metal of clay” defeated a procession of European chemists. One, Sir Humphry Davy of England, nevertheless gave the elusive metal a name—aluminum. His spelling prevails in the U. S. and Canada; almost everywhere else it’s spelled aluminium.


In 1825 Danish physicist Hans Christian Oersted, already famous for discoveries in

electromagnetism, turned his genius toward isolating the stubborn metal. Treating alumina with carbon and chlorine, then an amalgam of potassium, he at last obtained a mix of aluminum and volatile mercury. Boiling away the mercury, he suddenly gazed in awe at the long-sought quarry—a minute residue of powdery metal that “in color and luster somewhat resembles tin.”


Now scientists turned to the task of producing the metal in commercial quantities. Once again it proved stubborn. Napoleon III, perhaps envisioning his armies equipped with lightweight aluminum helmets and breastplates, personally promoted the research. Production costs dropped, but aluminum remained a semiprecious metal.


Metal Helmet


And so it was in 1884, when the U. S. prepared to dedicate the newly completed Washington Monument. To crown the great obelisk in Washington, D. C., a metallurgist created a gleaming pyramid of aluminum—at a hundred ounces one of the largest chunks ever assembled. Before the ceremony it sat in a window at Tiffany’s in New York City, awing sidewalk throngs.


Today, when your eye climbs the 555-foot stone shaft, it comes to rest on that same aluminum apex, still intact after nearly a century of battering by the elements.


Washington Monument


By a series of unlikely coincidences the aluminum age was about to dawn.


WOODSHED LABORATORY LED TO DISCOVERY


In the quiet college town of Oberlin, Ohio, student Charles Martin Hall became obsessed with finding an inexpensive way to produce aluminum. On graduating, the slight, intense son of a Congregationalist minister set up a crude laboratory in a woodshed behind the parsonage. His equipment included a skillet, a secondhand gasoline stove, and homemade crucibles.


Hall chose the process known as electrolysis—the use of electric current—in his effort to isolate the metal. The technique had failed Sir Humphry Davy eighty years before, but the youth added a step: Before unleashing the current, he dissolved the alumina in a molten solven t known as cryolite.


On February 23, 1886, a few months after his 22nd birthday, Hall connected a battery to a crucible of alumina-cryolite solution. Then he let the writhing current work. When the mix cooled, he shattered the congealed mass. In it glinted a clutch of silvery pellets—the seeds of an industry.


Incredibly for an event so long in coming, the same discovery occurred at almost the same moment, this time in Gentilly, France. Like Hall, Paul L. T . Héroult was also 22 years old, worked in a makeshift lab—his was tucked in a tannery—and also used molten cryolite to dissolve the alumina. Completing the strange parallel , both inventors died the same year, 1914.


Today virtually all the world’s aluminum is smelted by the Hall-Héroult process. Taking the place of their simple crucibles and batteries, great steel vats arranged in long potlines hold the dissolved alumina, and powerful electric currents tear it apart. Last year Hall-Héroult smelters around the world poured 16 million tons of aluminum, a third of it in the United States.


Smelting Bauxite


Smelting Bauxite

The infant industry spawned by Charles Hall depended upon two key ingredients-—bauxite, which could be mined in Arkansas in ample quantity, and also abundant electric energy to refine it. By chance, the evolution of electric power virtually paralleled that of aluminum. When the United States’ first large- scale hydroelectric plant spun to life at Niagara Falls in 1895, Hall’s fledgling company was among the first customers.


“Our needs today are the same as they were then—bauxite and energy,” said Alfred M. Hunt, a vice-president of Alcoa, the mighty Aluminum Company of America. His firm is the direct descendant of the enterprise based on Hall’s discovery.


NIAGARA FALLS WASN’T ENOUGH


Soon we needed more power than Niagara could supply,” he explained, “and we built our own hydroelectric plants from Canada to Tennessee. Starting in 1939, we plugged our smelters into the hydroelectric facilities burgeoning along the Columbia River in the Pacific Northwest. Today that area accounts for a third of all the aluminum manufactured in the U. S.


“We’ve developed natural-gas fields and lignite deposits in Texas, purchased coal fields in Kentucky and Indiana, and tapped the hydroelectric resources of Norway. We also developed hydropower in Surinam. Today the industry, which uses one percent of the nation’s total energy budget, generates a quarter of the electric power it consumes.”


In the early days of hydropower development, aluminum smelters were welcome customers for surplus power generated by Government-built dams. Now, as other competing demands of residential and othe r users soar, the aluminum companies encounter resentment of their heavy consumption and the low electricity rates they pay, often criticized as amounting to public subsidy. Some could face power cut-backs . In 1977 drought in the Pacific Northwest curtailed power production, forc-ing plants to close potlines.


“Long before the energy crisis started,” Mr. Hunt reminded me, “we were searching for ways to cut consumption . Since 1940 the industry has reduced by a third the amount of electricity needed during smelting. Also, Alcoa scientists developed a new smelting process requiring 30 percent less energy than the most efficient Hall- Héroult plant. In 1976 we opened a demonstration facility in Palestine, Texas.”


The Alcoa process, using chloride instead of fluoride in reducing alumina, could also alleviate a vexing pollution problem that the industry has strived to overcome. Decades ago farmers noticed that vegetation near smelters sometimes became very blighted. Worse, cattle that fed on affected plants became lame, and their teeth began wearing down rapidly. News reports dramatized the plight of the afflicted animals, and court cases known as “cow suits” ensued. The pollutant proved to be excessive fluoride emissions. Many companies sought to control such emissions, and today antipollution devices are prominent features at most smelters.


Part Two...



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