Experiments on mineral carbonation of CO2 in gabbro’s from the Sines massif– preliminary data from project InCarbon

Abstract

Portugal has committed to achieve carbon neutrality by 2050, but the current profile of emissions from the industrial sector requires that CO2 capture and storage technologies are deployed to accomplish that target. Amongst those technologies, mineral carbonation, i.e. the ability to precipitate carbonates by reacting the main cations present in silicates in mafic rocks (e.g. Ca2+, Fe2+) with CO2, turns these rocks the most stable and safe reservoirs. Project InCarbon embraces the challenge of studying mineral carbonation in texturally coarser rocks, namely gabbros and peridotites that outcrop in Alentejo, Portugal. In this sense the main goal of InCarbon is to infer the carbonation potential of those rocks under laboratory controlled conditions. The gabbro from Sines subvolvanic massif was selected for the first laboratory experiments, given its geochemical and mineralogical features as well its proximity with emission sources in the Alentejo region. As a global methodology, the specimens were mapped through VP-SEM-EDS and ATR-FTIR, after which they were submerged in a brine and CO2 mixture in cycles of 1, 4, 16 and 64 days at 80bar and 40ºC and later analyzed by the same two techniques. At the same time, compositional analyzes of brine and XRD were conducted. The first results show essentially a dissolution of silicates, causing an increase in surface roughness with contact time with the CO2 enriched brine. The behaviour of cations within brine after experiments is variable and no carbonates precipitation were detected.