Quarry waste ANTIgorite CARBonation

ANTICARB project originates from the desire to improve the environment by addressing processes in the extractive industry, focusing specifically on the serpentinite quarries in Valmalenco (Lombardy).

The products of this activity consist of more than 50% waste, dust, and fragments of magnesium silicate potentially capable of sequestering carbon dioxide (CO2) emitted by the industry itself to produce magnesite (magnesium carbonate), a compound widely used as both a raw material and a finished product. Exploiting these capabilities would mean making this sector of the industry a virtuous example of a “zero-emission and zero-waste” platform.

ANTICARB sets this ambitious goal, to be achieved with the financial support of the CARIPLO Foundation under the “Circular Economy for a Sustainable Future” grant.

The possibility of capturing CO2 while simultaneously transforming it into a useful material is based on the carbonation reaction, wherein magnesium silicates react with CO2 to form magnesium carbonates. Simple to say but challenging to achieve, as the reaction needs to occur under industrially manageable conditions, requiring supercritical conditions (P > 73.8 bar, T > 31.1 °C), achievable only in large industrial plants with an unfavorable energy expenditure.

Alternative methods exploit the effect of CO2 as a leaching and precipitating agent in the same process, accelerating the reaction by adding strongly acidic solutions and then concentrating the CO2 using basic solutions—a strategy that has a significant environmental impact and is far from a “green chemistry” approach.

Among physical methods, the use of microwaves has proven to be one of the most promising for promoting the carbonation reaction in magnesium silicates such as serpentinite.

ANTICARB aims to develop an innovative carbonation method optimized for antigorite waste from the most significant quarries in Valmalenco, converting a substantial fraction of Lombardy’s extractive industry into a circular economy. Antigorite is the high-temperature polymorph of the serpentinite group and reacts rapidly with CO2 due to its unique crystal structure.

To achieve this goal, ANTICARB intends to exploit the complementary expertise of experienced researchers (chemists, physicists, geologists, and engineers) and specialists in energy and environmental economics. Researchers from the University of Milano-Bicocca (Department of Environmental and Earth Sciences) and the Politecnico di Milano will investigate the carbonation reaction mechanism of antigorite at the atomic scale, utilising microwave-induced heating. They will employ techniques to monitor the reaction in real-time and in situ, aiming to identify zero-impact catalysis strategies.

The results of this scientific research will be utilised to address the waste powders from the quarries of Valmalenco and to establish a circular economy model based on the conversion of waste products and the simultaneous sequestration of CO2 emitted by the plants. The project has already received positive feedback from the Union of Lombard Municipalities in Valmalenco and will be conducted in collaboration with the University of Leoben in Austria.