Caractérisation et modélisation d'un procédé pilote de captage de CO2 par carbonatation des saumures alcalines et séparation des phases en colonnes de flottation

Abstract : Solvay process generates huge amounts of waste brines at alkaline pH containing portlandite, brucite and calcium silicate hydrates. Carbonation leads to lowering of pH which favors formation of two predominant phases: calcite and gypsum. The aim of this thesis is to develop carbonated waste brines valorization by phase separation in flotation column Study of carbonation in a batch reactor and in a carbonation pilot column shows it is preferable not to carbonate waste brines until thermodynamic equilibrium. Indeed dissolution of heavy metals occurs from a pH of about 7.5 thereby limiting discharge of brines in the environment. In addition, a sudden and incomplete carbonation is appropriate for phase separation by flotation. Flotation tests carried out in a 7.6 cm diameter and 3 m high column showed feasibility of the separation of the two calcium minerals using sodium oleate as a collector despite abundant literature for caution. The differences between the particle size of carbonates and sulfates and their surface hydration, as well as the high ionic strength of the medium allow an efficient separation of phases. Study of synthetic brines highlights the role of metal cations (nature, radius, charge…) on bubble coalescence in dynamic conditions in an environment with high ionic strength. Study of operation parameter performed on a 30.5 cm diameter and 10 m high column enabled the modeling of the column flotation process in order to provide a scale-up procedure of industrial process. Comparison of simulation results with actual results allows the determination of intensities of flotation subprocesses (attachment/detachment), and led to the proposal of an industrial plant with two flotation columns in series
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Patrice Piriou. Caractérisation et modélisation d'un procédé pilote de captage de CO2 par carbonatation des saumures alcalines et séparation des phases en colonnes de flottation. Alimentation et Nutrition. Université de Lorraine, 2014. Français. ⟨NNT : 2014LORR0136⟩. ⟨tel-01750985⟩

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