Héroult, Paul Louis Toussaint (1863-1914)

French metallurgist who developed the electrolytic manufacturing process for aluminium, simultaneously with US chemist Charles Hall. Héroult also invented the electric arc furnace for the production of steels.

Héroult was born in Thury-Harcourt, Normandy, and spent a year at the Paris School of Mines. Like Hall, Héroult succeeded in producing aluminium using his electrolytic apparatus at the age of 23. He patented the system in 1886. He also met with difficulty in commercializing the process, until large-scale production was begun by a joint German-Swiss venture in Neuhausen, Switzerland. Héroult also patented a method for the production of aluminium alloys 1888.

Like Hall in the USA, Héroult used direct-current electrolysis to extract aluminium from compounds, dissolving aluminium oxide in a variety of molten fluorides to find the best combination of material, and finding cryolite (sodium aluminium fluoride) the most promising. Héroult's process differed from Hall's in that the former used one large, central graphite electrode in the graphite cell holding the molten material.