Comprehensive analysis of direct aqueous mineral carbonation using dissolution enhancing organic additives Benjamin Bonfils, Carine Julcour-Lebigue, François Guyot, Françoise Bodénan, Pierre Chiquet, Florent Bourgeois To cite this version: Benjamin Bonfils, Carine Julcour-Lebigue, François Guyot, Françoise Bodénan, Pierre Chiquet, et al.. Comprehensive analysis of direct aqueous mineral carbonation using dissolution enhancing or- ganic additives. International Journal of Greenhouse Gas Control, Elsevier, 2012, 9, pp.334-346. 10.1016/j.ijggc.2012.05.009. hal-00773507 HAL Id: hal-00773507 https://hal-brgm.archives-ouvertes.fr/hal-00773507 Submitted on 22 Nov 2018 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. 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ISSN 1750-5836 Any correspondence concerning this service should be sent to the repository administrator: [email protected] Comprehensive analysis of direct aqueous mineral carbonation using dissolution enhancing organic additives Benjamin Bonfils a, Carine Julcour•Lebigue b, Franc¸ois Guyot c, Franc¸oise Bodénan d, Pierre Chiquet e, Florent Bourgeois a,∗ a Université de Toulouse, Laboratoire de Génie Chimique, 4 allée Emile Monso – BP 84234, 31030 Toulouse Cedex 4, France b CNRS, Laboratoire de Génie Chimique, 31030 Toulouse, France c Institut de Minéralogie et de Physique des Milieux Condensés (IMPMC) and Institut de Physique du Globe de Paris (IPGP), 4, Place Jussieu, 75005 Paris, France d BRGM, 3 Av. C. Guillemin, BP 6009, 45 060 Orléans Cedex 2, France e Centre Scientifique et Technique Jean Feger, TOTAL, Avenue Larribau, 64018 Pau Cedex, France article info a b s t r a c t Direct aqueous mineral carbonation using organic anions has been presented by many as a promising Keywords: strategy for mineral carbonation, on the basis that additives such as oxalate increase the rate and extent Mineral carbonation of dissolution of magnesium silicates several folds. Through geochemical modelling and detailed solid Magnesium silicate characterisation, this paper discusses and extends our current understanding of this process. The role of Oxalate disodium oxalate as a dissolution enhancing agent for olivine is thoroughly examined through experi• Geochemical modelling ments in which all phases are carefully analysed. We show that under 20 bar of CO2 pressure formation of strong oxalate–magnesium complexes in solution and precipitation of MgC2O4·2H2O (glushinskite) impede any chance of obtaining significant amounts of magnesium carbonate. Other promising ligands from a dissolution perspective, namely citrate and EDTA salts, are also investigated. Contrary to oxalate, these ligands do not form any solid by•products with magnesium, and yet they do not produce bet• ter carbonation results, thereby casting strong doubts on the possibility of developing a direct aqueous mineral carbonation process using organic salts. Geochemical modelling permits successful simulation of the dissolution kinetics of magnesium silicate using a shrinking particle model that accounts for the precipitation of glushinskite, amorphous silica and a magnesium phyllosilicate at advanced stages of the dissolution process. 1. Introduction with this process include a considerable consumption of acids and bases, and, to a lesser extent, a potentially high energy require• Ex situ mineral carbonation is considered a possible alterna• ment for the recycling of consumables (Newall et al., 1999). The tive to geological storage for CO2 mitigation (Metz et al., 2005). second school of thought, to which this work belongs, seeks to Its strongest asset is that it converts a CO2 gas stream into sta• develop a direct process whereby dissolution of (Mg,Ca)•bearing ble solid carbonates. Mineral carbonation was first investigated solids and precipitation of carbonates occur under the same nar• under dry conditions, however kinetics was invariably found to be row near•neutral pH range imposed by the process itself (O’Connor slow for consideration as an ex situ process (Lackner et al., 1995). et al., 2001; Gerdemann et al., 2007). The basis for this possibility Then, investigations shifted almost entirely towards aqueous min• is the demonstration by a number of research teams that a number eral carbonation, with two distinct schools of thought. The first of specific catalyst•like additives can accelerate silicate dissolu• one seeks to develop an indirect process with two sequential steps tion significantly under mild operating conditions (O’Connor et al., (Newall et al., 1999; Park and Fan, 2004; Teir et al., 2007), which 2001; Krevor and Lackner, 2009, 2011). can be optimised separately. The first step is the dissolution of Studies from NETL (O’Connor et al., 2001; Chen et al., 2006; (Mg,Ca)•bearing solids – either naturally occurring such as (Mg,Ca) Gerdemann et al., 2007) paved the way for direct aqueous carbon• silicates, or industrially produced such as mining wastes or slags ation of magnesium silicates with additives; mainly, they aimed to – under strongly acidic conditions, followed by a carbonate pre• quantify the overall process costs, and to obtain the highest pos• cipitation step under basic conditions. The most severe problems sible extent of reaction. Their work was based on a solution with 0.64 M NaHCO3 and 1 M NaCl (O’Connor et al., 2001) under a CO2 pressure of 170 atm and 180 ◦C. Comprehensive insights about the ∗ Corresponding author. Tel.: +33 534323633; fax: +33 534323700. effect of these inorganic additives are given by Chen et al. (2006). E•mail address: florent.bourgeois@inp•toulouse.fr (F. Bourgeois). Gerdemann et al. (2007) obtained high conversion (80% of olivine in http://doi.org/10.1016/j.ijggc.2012.05.009 that may occur in the solid phase. In particular, it is not known Nomenclature whether magnesium carbonates may have formed during their experiments, however unlikely this may be given the low solid con• aox activity of oxalate ion (–) centration and CO2 partial pressure they used. The dissolution focus + activity of proton (–) aH of their research did not permit their concluding about possible lim• KH+ apparent adsorption constant of proton (–) itations of the direct aqueous carbonation process. In particular, it K s solubility constant (–) is not possible from their data to assess the availability of dissolved k kinetic constant of SiO precipitation (molal s−1) SiO2(am) 2(am) magnesium to form magnesium carbonates, recalling that the very −1 ktalc kinetic constant of talc precipitation (molal s ) principle of the direct aqueous carbonation process is to allow the Kx apparent adsorption constant of oxalate ion (–) dissolution of silicates and the precipitation of carbonates to coex• −1 mox concentration of oxalate ion (molal or mol kg sol• ist under the same near•neutral pH (or weakly acidic) conditions. vent) One contribution of the present work is to complete their findings m concentration of amorphous silica (molal) SiO2(am) with the analysis of the solid phase, in conjunction with that of mtalc concentration of talc (molal) the species in solution, and find out whether operating conditions nB number of moles of olivine (in considered size class) exist whereby dissolved magnesium in solution is available to form at a given time (mol) magnesium carbonates. Q reaction quotient (–) The interactions between a number of organic ligands and mag• r specific dissolution rate (mol m−2 s−1) nesium silicates have received a great deal of attention in the rH+ specific dissolution rate due to surface protonation geochemical literature (Wogelius and Walther, 1991; Hänchen alone (ligand free system) (mol m−2 s−1) et al., 2006; Liu et al., 2006; Olsen and Rimstidt, 2008) since it is also SSA0 initial specific surface area of monodisperse particle a natural weathering mechanism for silicates. Olsen and Rimstidt class (m2 g−1) (2008) conclude that the oxalate ion accelerates forsterite leaching w0 initial weight of considered size class (g) by protons (dissociation of Mg O Si bonds). It is purely a sur• ˇ kinetic parameter measuring the ligand effect (–) face mechanism in which the oxalate ion bonds with the Mg atom, ˝ saturation index (–) which weakens the Mg O bond more efficiently than water alone, thereby increasing dissolution kinetics. This implies that ion con• centration, relative to the reactive surface area of particles, is a key parameter for the dissolution of magnesium. Finally, we may add 6 h) with the NaHCO3/NaCl system at high CO2 pressures and tem• that