SOCIETÀ DI MONTEPONI
MINIERA DI MONTEPONI
The Monteponi mine represents a milestone in the history of Italian mining industry, as well as the most outstanding Sardinian post-mining landscape. Despite already known in the XIV century, the local galena (lead, silver) and sphalerite (zinc) deposits began to be massively exploited only from 1850. On that year, a team of Ligurian-Piedmontese entrepreneurs guided by Paolo Antonio Nicolay acquired the mining concession from the Savoy government and founded the company Società di Monteponi. The mining activity was then developed through opening of two shafts (Pozzo Vittorio Emanuele II in 1863 and Pozzo Sella in 1872) and the construction of the first mechanic treatment facilities (Laveria Nicolay and Laveria Villamarina). In 1871 a 22 km long railway line between the mining site and the Portovesme harbor was completed too. A significant advancement occurred after the nomination of Erminio Ferraris as director in 1875, whose cleverness improved both mining and processing technologies. Initially, the urging problem of underground water removal was resolved through the excavation of a 4,2 km long sloping tunnel (Galleria Umberto I, completed in 1889) running from the lower levels of the mine down to the sea. The old treatment facilities were then replaced by two most modern gravity-separation plants – Laveria Calamine (1887) and Laveria Mameli (1893) – while an innovative smelting plant designed by Ferraris was added too (1894).
The turn of the century was signed by the discovery of a vast calamine (a zinc ore) deposit within the Campo Pisano mining concession (located a few km from Monteponi and owned by the same company). Starting from 1905 several attempts to recover zinc were made under the supervision of the new director Francesco Sartori. In 1914 a zinc oxide plant (2000 t/y) was established in the vicinity of the railway station. However, the difficulties emerged in treating ferrous calamine (poor ores) fostered the research of alternative methods. An experimental process of electrolysis was thus developed by Livio Cambi in 1921 and subsequently implemented on industrial scale at Monteponi. The large electrolysis plant (1924-26), the first of its kind in Europe, was equipped with 192 cells and had a capacity of 6500 t/y of zinc and 30 t/y of cadmium. To fulfill the need of sulfuric acid a devoted plant was also built (1928), using local pyrite and sphalerite as source of sulfur.
Further improvements occurred in the 1930s, starting from the construction of a couple of underground drainage facilities to allow excavations below the sea level. Above the ground, the old lead smelter was completely refurbished – reaching a production capacity of 6000 t/y of lead and 4000 kg/y of silver – while a new flotation unit was added to the ancient Mameli treatment plant. Such a remarkable development was due to an agreement signed in 1933 by Monteponi company and Montecatini mining-chemical enterprise, in which both tookover, with equal shares, another major Sardinian mining company in bankruptcy, the Montevecchio one. At the threshold of the Second World War the resulting conglomerate dominated the national non-ferrous mining and metallurgy sector with production shares equal to 75% of lead and 65% of zinc on the total.
The postwar development was signed by a general slowdown caused by three main factors. At the local level, the depletion of richest sulfur minerals. At the national level, the growing cost of electrical energy. At the international level, the increasing competition that followed the entrance of Italy into the European Economic Community. To face these issues the pre-war conglomerate was formed again: in 1961 Monteponi and Montevecchio mining companies merged into Monteponi-Montevecchio, subsidiary to 54% from Montecatini (later Montedison). The newly formed company proceeded to wind-up the outdated facilities, such as the lead smelter and the zinc oxide plant, while developing a way to recover zinc from tailings and poorer minerals. Therefore, to allow the electrolysis plant to remain active a new flotation plant was built (Laveria Galletti, 1961) and, more important, a Waelz smelter (1967), in which zinc oxide was obtained through volatilization in rotating kilns.
Despite these efforts the overall situation at Monteponi and related mines was unsatisfactory. In 1972 Monteponi-Montevecchio was "rescued" by the state mining corporation EGAM through its subsidiary SOGERSA. At the time, EGAM was participating to the creation of a large, state-owned non-ferrous metallurgical complex at Portovesme harbor. Such an investment aimed to allow Sardinian lead/zinc mines to survive while reacting to the closure of local coal mines. In 1978 the whole lead/zinc sector, comprising Monteponi mines and related processing facilities at Portovesme, was then transferred to SAMIM, the mining division of ENI (Italian oil and gas authority). However, this did not stop the inexorable decline of Monteponi mining centre, which turning point was the definitive closure of the zinc electrolysis plant in 1983. Remaining activities were slowly decommissioned until 1991, leaving just the last drainage facility for underground maintenance (until 1997).
The last picture shows the recently restored Pozzo Sella (former main shaft). © Michele Pili.
AA. VV. (1950), Società di Monteponi 1850-1950, Tipografiai Vincenzo Bona, Torino.
Mezzolani, S., Simoncini, A. (2001), Sardegna da Salvare. Storia, Paesaggi e Architetture delle Miniere, Editrice Archivio Fotografico Sardo, Nuoro.
Sardegna - Miniere di Argento Piombo e Zinco a Iglesias (1932) | An overview of lead and zinc processing at Monteponi.
La miniera di piombo argentifero di Monteponi in Sardegna (Giornale Luce 11/1934) | A brief presentation of the Monteponi mine.