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The Geothermal Museum:
Larderello (Temporary Headquarters)
[Historical Notes] [The Factories]
[The
Chemistry] [Drilling] [Electricity]
The Chemistry
Industrial activity at Larderello began with the exploitation of the geothermal waters to produce boric acid. Originally
boric acid was imported to Europe from Tibet where it was collected on the shores of hot water lakes; its original
name was TINKAL. The Arabs, who called it BURAQ, brought it to Spain and from there to the rest Europe.
Currently boric acid is used to manufacture enamels for the ceramics industry, in welding, glass making, pharmaceuticals
and other fields.
In 1777 Francesco Hoefer, director of the Pharmacies of the Grand Duchy of Tuscany detected the presence of boric
acid in the waters of the hot lakes. But the first attempts at producing boric acid on an industrial scale were
only made in 1818.
The original method of evaporating the boracic water in steel boilers using wood fires proved too expensive as
wood became scarce and it had to be brought from more and more distant places.
In 1827 Frangois De Larderal used the natural steam instead of heat created by burning wood to evaporate the boracic
waters.
To achieve this he built the LAGONE COPERTO, that is a masonry dome over a natural hot lake; it collected the steam
and allowed it to escape at a pressure that could provide enough heating power to the boilers to evaporate the
boracic waters. When the boric salts precipitated, they contained large amounts of water. Originally, this water
was removed by a press and then by a steam centrifuge. This device used the steam's pressure to rotate a drum containing
the boric salts. The still damp salts were then dried in the terrazzi, large rooms with steam circulating under
the floors. The salts were spread on the hot floors until dry and ready to ship.
The steam power was also used to pump the boracic waters from one part of the factory to another, and from the
lower to the upper part of the evaporating boilers using donkey pumps driven by the pressurized steam.
Steam pressure was also used to extract the boracic waters from small openings made to get greater amounts of boracic
water, feeding machines known as pressatori or "pressers".
Nowadays boric acid is produced at Lardarello using a boron mineral, Colemanite, which is imported from Turkey
and Argentina.
[Historical
Notes] [The Factories] [The Chemistry]
[Drilling] [Electricity]
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