Cristallisation du bicarbonate de sodium: étude pratique et théorique

Abstract : Recently, there is an increased demand for sodium bicarbonate crystals with specific properties. In the present study, the crystallization reaction of sodium bicarbonate is performed in a three-phase medium in which many phenomena such as mass transfer, nucleation and crystal growth occurred. The objective of this work is to study the impact of operating parameters, additives and reactor technology on the crystallization of sodium bicarbonate in order to obtain crystals with important size and high bulk density. The experiments carried out in a MSMPR (Mixed Suspension Mixed Product Removal) reactor have shown that the addition of calcium through a calcium chloride solution in the reaction mixture improves the crystal morphology, reduces the nucleation rate and weakly influences the crystal growth rate. When a mixture of sodium polystyrene sulfonate (NaPSS) and calcium chloride is used, more compact crystals with smoother surfaces and marked edges are obtained. Conversely, the use of calcium chelating additives such as calcium citrate affects the quality of sodium bicarbonate crystals and thus is prohibited for industrial use because the filtration and drying steps are much more difficult. Finally, the transposition from a MSMPR reactor to a fluidized bed reactor allows, under the same operating conditions, a significant improvement of the solid quality by producing big spheroidal particles
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Antoine Gérard. Cristallisation du bicarbonate de sodium: étude pratique et théorique. Alimentation et Nutrition. Université de Lorraine, 2014. Français. ⟨NNT : 2014LORR0072⟩. ⟨tel-01750795⟩

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