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Aluminum: The Light Metal—Part I Aluminum, one of the most widely used structural metals in modern industry, is produced in quantities exceeded only by steel. Its light weight, corrosion resistance, high strength after heat treatment, and global availability of bauxite ores make aluminum attractive for everything from kitchen utensils to spacecraft.

Metallurgy Lane, wo young men living an ocean apart—both of the pot and was drained off periodically. authored by just 22 years old—invented the same novel He immediately started applying for patent ASM life member T process for reducing aluminum from its ore. protection for his invention, which required find- Charles R. Simcoe, One was an American chemist, Charles Martin ing money and hiring a patent attorney. His patent is a yearlong series Hall, and the other was a French metallurgist, Paul was formally filed on July 9, 1886. However, the dedicated to the early Heroult. Both lived from 1863 to 1914. Their new U.S. Patent Office notified history of the U.S. metals process would remain the world’s method for mak- Hall that another applica- and materials industries ing aluminum for the next 100 years and beyond, tion for the same process along with key and propelled aluminum and its alloys into second had been filed on April 23, milestones and place as the most widely used structural metal, just 1886, by a Frenchman developments. after steel. named Paul L.T. Heroult, The driving force behind the search for low- meaning that Heroult’s cost aluminum was not demand for the product, but patent application predated knowledge of the vast resource of aluminum-con- Hall’s by more than two taining minerals in easy reach within the earth’s months. This patent inter- Paul Heroult. crust. It had long been known that large deposits of ference was resolved when Courtesy of alcoa.com. aluminum-containing clays constituted great quan- Hall proved that he had re- tities of aluminum, especially in ores called bauxite duced his invention to practice on February 23, named after a region in France called Baux where 1886, where Heroult had only his filing date of the ore was first identified. Bauxite is widely scat- April 23, 1886. Hall, therefore, became the inventor tered around the globe, mostly in tropical climates. of record in the U.S. by a mere two months. Hall then set out to find financial supporters to Charles Martin Hall carry his process into production. His first success- Charles Martin Hall was born in Thompson ful contact was with the Cowles brothers who Township, Geauga County, Ohio, in December owned the Cowles Electric Smelting and Alu- 1863. The Hall family moved to Oberlin, Ohio, minum Co. of Cleveland. The Cowles had a process about 35 miles southwest of Cleveland, when the for making an alloy of copper containing alu- children were old enough for college. Even though minum called aluminum bronze. Hall joined the Oberlin College is primarily a liberal arts school, a Cowles Co. at their plant in Lockport, N.Y., with a number of science courses were taught including salary of $75 per month for three months. If his ex- chemistry by Professor Frank Fanning Jewett, and periments were satisfactory after that time, he Hall took his courses. would receive $750 and the company would con- Charles Martin Hall After graduating in spring 1885, Hall set up his tinue to support his work. An option for further re- in 1905, age 42. Courtesy of now-famous experiments in a woodshed behind wards was never fulfilled due to disagreements alcoa.com. the family home with the assistance of his sister between Hall and the brothers. Hall parted com- Julia, also an Oberlin chemistry student. In just a pany with the Cowles before making progress in few weeks in the winter of 1886, Hall developed his aluminum production. method for making aluminum. His invention en- However, Hall had worked with a manager at tailed dissolving aluminum oxide in the mineral the Cowles plant, Romaine C. Cole, who had done cryolite. The molten bath was contained in a pot some work on aluminum for a testing company in lined with graphite and with graphite electrodes in- Pittsburgh named Hunt and Clapp. When it be- serted into the bath. A low voltage/high amperage came clear to Hall that the Cowles were not sup- electric current was passed from the electrodes to porting him, Cole recommended that they contact the lining, where aluminum metal was separated Captain Alfred E. Hunt. Cole arranged a meeting from the oxide. Aluminum collected at the bottom with some of Hunt’s acquaintances in July 1888 to

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An aluminum plaque at 3220 Smallman Street, Pittsburgh, commemorates the birthplace of aluminum. Courtesy of alcoa.com.

Bauxite ore. U.S. public domain image. discuss forming a company to support Hall’s experi- ments in scaling up the process to pilot production. Hall joined the group a week later when a second meeting was held with Hunt presiding. This meeting of Hall, Cole, Hunt, and a small group of Pittsburgh men known to Hunt from the steel industry and from his testing laboratory formed the technical and finan- cial support of what would become the American aluminum industry. Hunt and the other financial supporters agreed to organize an entity called The Andrew Mellon. Courtesy of Pittsburgh Reduction Co. and to raise $20,000 to Carnegie Museum build and equip a pilot plant to demonstrate the value of Art, Historic of Hall’s process for producing low-cost aluminum. Pittsburgh image Next to Hall, Hunt was the most important man collection. involved in developing aluminum as a commercial business. While Hall and others were primarily in- terested in technology and production, Hunt car- ried the burden of financing, managing, marketing, Interior of the Smallman Street works of the Pittsburgh and selling the product. Alfred Ephrehem Hunt was Reduction Co., circa 1889. Courtesy of alcoa.com. born in Massachusetts in 1856 and graduated from MIT in mining and metallurgy in 1876. In 1883, he loan. The Mellon brothers, Andrew and Robert, and George Clapp bought out the owners of The supplied a larger loan of $25,000 and later took a po- Pittsburgh Testing Laboratory and renamed it Hunt sition in the company by buying 60 shares from Hall and Clapp. at $100 per share. Arthur Vining Davis. Courtesy of alcoa.com. The pilot plant The move to New Kensington Hall and Cole built a pilot plant on Smallman The Pittsburgh Reduction Co. soon outgrew the Street in Pittsburgh and began to set up reduction pilot plant on Smallman Street and the Mellon cells and a motor-generator set to provide electricity. brothers encouraged them to locate a production Their first production run after numerous startup plant in New Kensington, northeast of Pittsburgh. problems yielded a few marble-sized particles on By now, Hall had discovered that by increasing the Thanksgiving Day 1888. Thus, the modern world of size of the reduction pots and therefore the electric aluminum was born. current, he could maintain the heat to keep the It turned out that Hall and Cole were not com- molten bath at the necessary temperature without patible as fellow workers in running the pilot plant, an outside heat source. In addition, after scaling up so Cole was replaced by a young worker from Hunt’s the operation, less energy was needed per pound of testing laboratory, Arthur Vining Davis. Hall and aluminum produced. The Mellons purchased a Davis soon increased production at the pilot plant stock offering at this time of 500 shares at $60 per to 50 pounds per day, selling at $8 per pound. By share. This allowed them seats on the board of di- adding two new dynamos, production increased to rectors. The Mellons were now insiders and not 450 pounds per day, but the price had dropped to simply bankers providing loans. $2 per pound. Realizing the need to achieve produc- tion levels to obtain economies of scale, and in need For more information: of funds to meet daily obligations, the company’s Charles R. Simcoe can be reached at [email protected]. principals approached the Mellon Bank for a $4000 For more metallurgical history, visit metals-history.blogspot.com.

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