On the potential use of quarry waste material for CO2 sequestration

Abstract The use of solid wastes rich in Ca 2+ , Mg 2+ and Fe 2+ for the ex situ sequestration of CO 2 could provide an economically and technologically viable option for the reduction of anthropogenic CO 2 emissions. Here, we investigate for the first time the potential use of waste materials from mafic rock quarries as a feedstock for the sequestration of CO 2 by ex situ mineral carbonation. The experimental procedure was performed on a waste material from a dolerite quarry operating in the Troodos ophiolite (Cyprus). The ball milling process was applied to this quarry waste in order to create nanomaterials with enhanced CO 2 adsorption capacity. Through CO 2 chemisorption followed by temperature-programmed desorption (CO 2 -TPD) experiments, the optimum ball milling conditions were found (20 h of wet ball milling with 50 wt% ethanol as process control agent), leading to an enhancement of the CO 2 -storage capacity of the waste material by a factor of ∼120. This enhancement of CO 2 uptake is closely related to (i) the reduction of particle size to the nanoscale, (ii) the structural disordering of the constituent silicate minerals, and (iii) the presence of augite nanocrystals after ball milling. The experimental results suggest that waste materials from dolerite quarries may indeed be used as feedstock for the ex situ mineralization of CO 2 . They also strongly demonstrate that ball milling is a very promising technique for optimizing the ex situ carbonation of this waste material; thus the proposed methodology could be a fundamental part of a future carbon sequestration strategy.