Reaction Mechanism for the Aqueous-Phase Mineral Carbonation of Heat-Activated Serpentine at Low Temperatures and Pressures in Flue Gas Conditions

Abstract

Mineral carbonation is known as one of the safest ways to sequester CO2. Nevertheless, the slow kinetics and low carbonation rates constitute a major barrier for any possible industrial application. To date, no studies have focused on reacting serpentinite with a relatively low partial pressure of CO2 (pCO2) close to flue gas conditions. In this work, finely ground and heat-treated serpentinite [Mg3Si2O5(OH)4] extracted from mining residues was reacted with a 18.2 vol % CO2 gas stream at moderate global pressures to investigate the effect on CO2 solubility and Mg leaching. Serpentinite dissolution rates were also measured to define the rate-limiting step. Successive batches of gas were contacted with the same serpentinite to identify surface-limiting factors using scanning electron microscopy (SEM) analysis. Investigation of the serpentinite carbonation reaction mechanisms under conditions close to a direct flue gas treatment showed that increased dissolution rates could be achieved relative to prior work, with an average Mg dissolution rate of 3.55 × 10(-11) mol cm(-2) s(-1). This study provides another perspective of the feasibility of applying a mineral carbonation process to reduce industrial greenhouse gas (GHG) emissions from large emission sources.

Effect of pCO 2 on direct flue gas mineral carbonation at pilot scale

“…Similar work conducted in laboratory scale led to a reaction efficiency of 0.28 g of CO 2 converted.g of serpentine -1 (Pasquier et al, 2014b). The difference between the results can be attributed to several factors.…”

“…In this way, different studies focused on using a diluted CO 2 stream, similar at some industrial flue gas (Pasquier et al, 2014a;Werner et al, 2014). Results showed that reaction mechanism, kinetics where similar as observed for pure CO 2 treatments and led to promising results Pasquier et al, 2014b). In addition, dissociation of gas treatment steps and carbonates precipitation leads to the production of high purity products giving significant incomes.…”

Formation of magnesite and hydromagnesite from direct aqueous carbonation of thermally activated lizardite

“…Recent research has shown that it is feasible to use heat treated serpentine to treat directly the flue gas from a cement plant containing 18% CO 2 instead of pure CO 2 . This research shows that it is possible to produce pure Nesquehonite by precipitating in a separate step.…”

Serpentinites: Mineral Structure, Properties and Technological Applications

“…[53][54][55][56][57] Direct carbonation involving serpentinite and forsterite rocks has been proposed. [58][59][60][61] In this case, the CO 2 is dissolved in solution forming carbonic acid. This causes a pH reduction in the medium, allowing the dissolution of the magnesium silicate and the subsequent carbonation.…”