Carbonation of serpentinite or asbestos mine tailing is a passive, weathering-related process that take advantage of the thermodinamically driven natural transformation of ultramafic rocks into carbonate and thus it is cost and energy effective. The enhancement of this natural weathering is a challenge including multiple advantages: CO capture, and remediation 2 of asbestos tailing. Here, we present an example of natural carbonation of a small mine dump at Montecatelli (Tuscany, Italy). At Montecastelli (Tuscany, Italy), a pluri-kilometric body of serpentinite, embedded in shales, has been deeply eroded by the Pavone River providing good exposures and sections. The central portion of the serpentinite body host a small copper ore deposit that was intermittently exploited during the XIX century, and was definitively closed in 1869. Bornite, chalcopyrite, chalcocite and pyrite veinlets and nodules, in a chlorite-serpentine-brucite-amphibole soapy gangue, characterize narrow deformation zones crosscutting the serpentinites. Most of the low-grade Cu-ore extracted in the past was not reliable for industrial processing and directly dumped in front of the entrances of the mine, forming by the time a small mining dump. Mining activity stopped 60 years ago.Intense natural carbonation produced crust of hydrated Mg-carbonates (hydromagnesite, nesquehonite, manasseite, pyroaurite, brugnatellite) coating the serpentinite clasts of the mining dump and the serpentinite walls of the mine tunnels. The Montecastelli carbonated serpentinite mine tailings represent an example of rapid atmospheric CO2 uptake. Their study improved our knowledge of the carbonation processes. Future quantification of the amount of carbon sequestered in geologic samples from Montecastelli would give an estimate for the sequestration capacity of ultramafic mine tailings in general and will provide a framework for the development of standard protocol for enhanced mineral sequestration at mine sites.

Carbonation of serpentine mine tailing: the example of Montecastelli mine (Tuscany, Italy)

BEDINI, FEDERICA;
2013-01-01

Abstract

Carbonation of serpentinite or asbestos mine tailing is a passive, weathering-related process that take advantage of the thermodinamically driven natural transformation of ultramafic rocks into carbonate and thus it is cost and energy effective. The enhancement of this natural weathering is a challenge including multiple advantages: CO capture, and remediation 2 of asbestos tailing. Here, we present an example of natural carbonation of a small mine dump at Montecatelli (Tuscany, Italy). At Montecastelli (Tuscany, Italy), a pluri-kilometric body of serpentinite, embedded in shales, has been deeply eroded by the Pavone River providing good exposures and sections. The central portion of the serpentinite body host a small copper ore deposit that was intermittently exploited during the XIX century, and was definitively closed in 1869. Bornite, chalcopyrite, chalcocite and pyrite veinlets and nodules, in a chlorite-serpentine-brucite-amphibole soapy gangue, characterize narrow deformation zones crosscutting the serpentinites. Most of the low-grade Cu-ore extracted in the past was not reliable for industrial processing and directly dumped in front of the entrances of the mine, forming by the time a small mining dump. Mining activity stopped 60 years ago.Intense natural carbonation produced crust of hydrated Mg-carbonates (hydromagnesite, nesquehonite, manasseite, pyroaurite, brugnatellite) coating the serpentinite clasts of the mining dump and the serpentinite walls of the mine tunnels. The Montecastelli carbonated serpentinite mine tailings represent an example of rapid atmospheric CO2 uptake. Their study improved our knowledge of the carbonation processes. Future quantification of the amount of carbon sequestered in geologic samples from Montecastelli would give an estimate for the sequestration capacity of ultramafic mine tailings in general and will provide a framework for the development of standard protocol for enhanced mineral sequestration at mine sites.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/512469
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