Ex-situ mineral carbonation: resources, process and environmental assessment (Carmex project)

This article presents the main results of the Carmex project (2009-2012), whose purpose was to review the feasibility of ex-situ mineral carbonation in terms of resource availability, performance of the aqueous mineral carbonation process and life cycle analysis criteria. This collaborative project looked at a wide range of generic issues about this CO2 mitigation option, with particular views on assessing its potential in the context of New-Caledonia. Indeed, insularity and local abundance of 'carbonatable' rocks and industrial wastes (i.e. rich in MgO, CaO, if not Fe(II)O), coupled with significant GHG emissions from first-class nickel pyrometallurgical industries, make it a potential candidate for application of ex-situ mineral carbonation. The project conducted a worldwide analysis of the potential of ex-situ mineral carbonation using a dedicated SIG-based tool. Using a variety of materials the project also reviewed a number of critical issues associated with the aqueous mineral carbonatation process itself, with promising perspectives. Finally, through life cycle analysis of the system as a whole, ex-situ mineral carbonation was compared to mainstream CSC solutions. It was concluded that the viability of this CO2 storage option is located at the level of the process itself and lies with the optimisation of its operating conditions

Comprehensive analysis of direct aqueous mineral carbonation using dissolution enhancing organic additives.

Direct aqueous mineral carbonation using organic anions has been presented by many as a promising strategy for mineral carbonation, on the basis that additives such as oxalate increase the rate and extent of dissolution of magnesium silicates several folds. Through geochemical modelling and detailed solid characterization, this paper discusses and extends our current understanding of this process. The role of disodium oxalate as a dissolution enhancing agent for olivine is thoroughly examined through experiments 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 better 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

Development of an attrition-leaching hybrid process for direct aqueous mineral carbonation

Mineral carbonation is the single most eligible companion solution to geosequestration for mitigation of anthropic CO2 emissions on a large scale. Amongst its possible pathways, direct aqueous mineral carbonation stands out as one of the most promising ones. The originality of the present work lies in the transposition of the concomitant exfoliation/mineralisation concept, which was first proposed by the mineral carbonation research group from the Arizona State University in early 2000s, inside a dedicated attrition environment, more specifically inside a stirred bead mill. Experimental results and analyses bring definite proofs about the possibility and synergy of concomitant exfoliation and mineralisation. Given high carbonation yield for olivine and serpentinised ores (up to 35% in 5 h and 80% in 24 h in water, and 70% in 5 h with inorganic additives) and the capacity of stirred mills to process mining size throughputs, this work leads to real perspectives for developing large scale robust solutions for direct aqueous mineral carbonation

Ex situ mineral carbonation for CO2 mitigation: Evaluation of mining waste resources, aqueous carbonation processability and life cycle assessment (Carmex project)

This article presents the main outputs from the multidisciplinary Carmex project (2009–2012), which was concerned with the possibility of applying ex situ mineral carbonation concepts to mafic/ultramafic mining wastes. Focus points of the project included (i) matching significant and accessible mining wastes to large CO2 emitters through a dedicated geographical information system (GIS), (ii) analysis of aqueous carbonation mechanisms of mining waste and process development and (iii) environmental assessment of ex situ mining waste carbonation through life cycle assessment (LCA) methodology. With a number of materials associated with the mining sector, the project took a close look at the aqueous carbonation mechanisms for these materials and obtained unexpected carbonation levels (up to 80%) by coupling mechanical exfoliation and reactive carbonation. Results from this work support the possibility of processing serpentine-rich peridotites without applying the classical first step of heat activation. Perspectives are also given for the carbonation of Ni-pyrometallurgical slag available closed to ultramafic mining residues. LCA of the mining waste carbonation system as a whole made it clear that the viability of this CO2 storage option lies with the carbonation process itself and optimisation of its operating conditions. By combining the body of knowledge acquired by this project, it is concluded that New Caledonia, with its insularity and local abundance of ‘carbonable’ rocks and industrial wastes coupled with significant greenhouse gas (GHG) emissions from world-class nickel pyro and hydrometallurgical industries stands out as a strong potential candidate for application of ex situ mineral carbonation

Utilisation de tensioactifs réactifs en polymérisation du chloroprène en émulsion (préparation d'adhésifs aqueux destinés au collage des semelles dans l'industrie de la chaussure)

Ce travail s'est donné comme objectif principal la préparation d'adhésifs polychloroprène universels et exempts de tout solvant organique volatil, capables d'égaler leurs homologues en solution pour le collage de l'ensemble des supports actuellement utilisés en tant que semelles dans l'industrie de la chaussure (SBR, PVC). La réalisation de cet objectif s'appuie sur deux idées totalement distinctes : la substitution du tensioactif industriel par un tensioactif polymérisable et la mise au point d'un nouveau procédé de synthèse de latex polychloroprène fonctionnalisés par des groupements (méth)acryliques. Un tensioactif maléique (HEC16) a été engagé en polymérisation en émulsion du chloroprène à 40 % de taux de solide. LE pourcentage de HEC16 présent en surface des particules après lavage du latex est élevé et varie entre 45 % et 76 %. La formation de gel dès de faibles valeurs de conversion a donné lieu à une étude complète des mécanismes de gélification du chloroprène. Il ressort que le principal paramètre à contrôler est la durée de vie des radicaux dans les particules, liée au nombre de particules nucléées et au flux de radicaux. Un procédé innovant de fonctionnalisation des latex polychloroprène a été proposé, en association avec le contrôle du taux de gel. Il permet la préparation de particules composites où coexistent une phase polychloroprène et une phase essentiellement composée de poly(acrylate de butyle) et de poly(méthacrylate de méthyle). Il est remarquable de constater que les forces d'adhérence des latex polychloroprène fonctionnalisés sur des assemblages entièrement non poreux SBR / SBR rejoignent les valeurs des adhésifs polychloroprène en solution sur des assemblages semi-poreux. Dans nos conditions expérimentales, aucune amélioration n'a toutefois été apportée en terme de collage PVC.LYON1-BU.Sciences (692662101) / SudocSudocFranceF