Heroult, Paul Louis

Hall-Heroult process -> aluminum production, -> Hall, Charles Martin, and -> Heroult, Paul Louis Toussaint... 

This picture changed in the 1886 when an American chemist, Charles Martin Hall (1863— 1914), and a French chemist, Paul Louis-Toussaint Heroult (1863—1914), both discovered, at about the same time, a new process for extracting aluminum from molten aluminum oxide by electrolysis. (It might be noted that both discoverers have the same birth and death dates as well as the same date of discovery.) Hall was inspired by his teacher to find a way to inexpensively produce aluminum metal. He wired together numerous wet cells to form a battery that produced enough electricity to separate the aluminum from the melted aluminum oxide (mixed with the minerals cryolyte or fluorite), by the process known as electrolysis. Hall formed the Pittsburgh Reduction Co., which is now known as the Aluminum Company of America, or Alcoa. His company produced so much aluminum that the price dropped to about sixty cents per kilogram. 

At about the same time that Hall perfected his process, Dr. Paul-Louis-Toussaint Heroult, a young French chemist of the same age, made the same discovery independently. Dr. Heroult was bom in 1863 at Thury-Harcourt in the department of Calvados. When the war of 1870 broke out, he was sent to live with his grandfather in London, and thus he acquired a good command of the Enghsh language. Three years later he returned to France to continue his education. 

Paul-Louis-Toussaint Heroult. 1863-1914. French metallurgist. Independent discoverer of the electrolytic method of preparing aluminum now known as the Hall-Heroult process. He designed electric furnaces, and made many important contributions to the electrometallurgy of iron and steel... 

Using the Hall process exclusively, the aluminum industry in the United States alone produces more than 150,000 tons of aluminum each year, and it is impossible to estimate the magnitude of probable future production. The commercial product obtained directly by electrolysis has a purity greater than 99%. It is of interest to note that a few months following the discovery of the Hall process an identical method was discovered independently by the French chemist Paul-Louis-Toussaint Heroult. 

Although aluminum was one of the last metals to be commercialized, it has been recognized for centuries. Aluminum was first recognized by the Romans as an astringent substance, and they called it alum . By the Middle Ages it was manufactured as alum stone , a subsulfate of alumina and potash. In 1825, Hans C Oersted was able to isolate a few drops of the raw material, and then by 1886 it had patents from both Charles Martin Hall of the United States and Paul-Louis-Toussaint Heroult of France. Aluminum was commercialized in industry by the end of the nineteenth century. 

Paul Louis Toussaint Heroult obtained a patent in April 1886, just seven weeks before the American Charles Hall obtained his, for processes to make... 

Charles Martin Hall in America and Paul Louis Toussaint Heroult in France independently observed the same phenomenon. Each discovered that passing an electric current through a solution of pure aluminum oxide in cryolite (sodium aluminum fluoride) produced the pure metal. Both men were only twenty-two years old at the time. 

The first attempts to isolate aluminium in its metallic form were performed in 1825 by Hans Christian Oersted, a Danish physicist and chemist, and fulfilled in 1827 by Friedrich Wohler, a German chemist, who isolated the pure metal from aluminium trichloride via reduction with potassium. The viable scaling-up of aluminium production was a rather long process that led, on the one hand, to the sodium aluminate process of Carl J. Bayer disclosed in 1887 producing pure aluminium oxide and, on the other hand, to the process of Charles M. Hall and Paul-Louis Toussaint Heroult" coinvented independentiy in 1886, in which aluminium oxide is dissolved in cryolite to yield via electrolysis pure metallic aluminium. 

In France, Paul Louis Heroult discovered the same energy-intensive process at about the same time, and the method is consequently called the Hall-Heroultprocess. In one of those amazing coincidences, Heroult was born 8 months before Hall and also died 8 months before him. Both men were 23 years old when they discovered a process that changed human history, not to mention their own lives. 

The manufacturing process of aluminium by electrolysis of molten alumina was developed in France by Paul Louis Toussaint Heroult (1863-1914), who filed a patent on April 23,1886, and in the United States by Charles Martin Hall (1863-1914), who filed his patent on July 9, 1886. Both had succeeded in dissolving alumina (melting point 2030 °C) in cryolithe AIF3 3NaF, which melts at 977 °C the industrial melt contained about 2 or 3% alumina. 

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